5,420 results on '"Xenon Radioisotopes"'
Search Results
2. Overview of temporary radioxenon background measurement campaigns conducted for the CTBTO between 2008 and 2018
- Author
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Jonathan Baré, Abdelhakim Gheddou, and Martin B. Kalinowski
- Subjects
Air Pollutants, Radioactive ,Radiation Monitoring ,Nuclear Reactors ,Health, Toxicology and Mutagenesis ,International Cooperation ,Environmental Chemistry ,General Medicine ,Pollution ,Waste Management and Disposal ,Xenon Radioisotopes - Abstract
The Comprehensive Nuclear-Test-Ban Treaty (CTBT) specifies that an overall network of at least 40 International Monitoring System (IMS) stations should monitor the presence of radioxenon in the atmosphere upon its entry into force. The measurement of radioxenon concentrations in the air is one of the major techniques to detect underground nuclear explosions. It is, together with radionuclide particulate monitoring, the only component of the network able to confirm whether an event originates from a nuclear test, leaving the final proof to on-site inspection. Correct and accurate interpretation of radioxenon detections by State Signatories is a key parameter of the verification regime of the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). In this context, the discrimination between the highly variable radioxenon background generated by normal operations of nuclear facilities and CTBT-relevant events is a challenging, but critical, task. To this end, the radioxenon background that can be expected at IMS noble gas systems must be sufficiently characterized and understood. All activities conducted to study the global radioxenon background are focused on the calibration and performance of the verification system as described in the Treaty. The unique CTBTO noble gas system network is designed to optimally covering the globe. By the end of 2019, 31 systems were put in operation, 25 of which being already certified. It took two decades from the first experimental setup of noble gas system in the field to reach this stage of maturity. In the meantime, it was an urgent need to gain empirical evidence of atmospheric radioxenon concentrations with the full spectrum of characteristics that IMS noble gas systems may be observing. This experience was significantly advanced through temporary measurement campaigns. Their objective was to gain the additional necessary knowledge for a correct understanding and categorization of radioxenon detections. The site selection for these campaigns put emphasis on regions with low coverage by the initially few experimental noble gas systems at IMS locations or where potential interferences with normal background might be observed. Short-term measurements were first initiated in 2008. Sites of potential interest were identified, and campaigns up to few weeks were performed. Based on the findings of these short campaigns, transportable systems were procured by the CTBTO. Longer temporary measurement campaigns were started afterwards and operated by local hosts in different regions of the globe. Site selections were based on purely scientific criteria. Objectives of the measurement campaigns were continually reassessed, and projects were designed to meet the scientific needs for radioxenon background understanding as required for nuclear explosion monitoring. As of today, several thousands of samples have been collected and measured. Spectra of temporary measurement campaigns were (and are still) analysed in the International Data Centre (IDC). As they are not part of the CTBT monitoring system, no IDC product is generated. Analysis results are stored in a non-operational database of the CTBTO and made available, together with raw data, to authorized users of States Signatories through a Secure Web Portal (SWP) and to scientific institutions for approved research projects through a virtual Data Exploitation Centre (vDEC) after signing a cost-free confidentiality agreement (https://www.ctbto.org/specials/vdec). This paper aims at providing an overview of the temporary measurement campaigns conducted by the CTBTO since the very first field measurements. It lays out scientific results in a systematic approach. This overview demonstrates the asset of radioxenon background measurement data that have been collected with a wide variety of characteristics that may be observed at IMS stations. It bears a tremendous opportunity for development, enhancement and validation of methodologies for CTBT monitoring. In 2018, a campaign started in Japan with transportable noble gas systems in the vicinity of the IMS station RN38 in Takasaki. It will be described separately once the measurements are completed.
- Published
- 2022
3. Determining the source of unusual xenon isotopes in samples
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Paul W. Eslinger, James Ely, Matthew W. Cooper, Michael Foxe, James C. Hayes, Michael F. Mayer, Mark E. Panisko, and Ramesh Sarathi
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Radioisotopes ,Xenon ,Air Pollutants, Radioactive ,Radiation Monitoring ,Health, Toxicology and Mutagenesis ,Environmental Chemistry ,Xenon Isotopes ,General Medicine ,Pollution ,Waste Management and Disposal ,Xenon Radioisotopes - Abstract
Three unusual radioactive isotopes of xenon
- Published
- 2022
4. Uncertainty quantification of atmospheric transport and dispersion modelling using ensembles for CTBT verification applications
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Pieter De Meutter and Andy W. Delcloo
- Subjects
Air Pollutants, Radioactive ,Radiation Monitoring ,Health, Toxicology and Mutagenesis ,Nuclear Power Plants ,Uncertainty ,Environmental Chemistry ,General Medicine ,Pollution ,Waste Management and Disposal ,Xenon Radioisotopes - Abstract
Airborne concentrations of specific radioactive xenon isotopes (referred to as "radioxenon") are monitored globally as part of the verification regime of the Comprehensive Nuclear-Test-Ban Treaty, as these could be the signatures of a nuclear explosion. However, civilian nuclear facilities emit a regulated amount of radioxenon that can interfere with the very sensitive monitoring network. One approach to deal with this civilian background of radioxenon for Treaty verification purposes, is to explicitly simulate the expected radioxenon concentration from civilian sources at monitoring stations using atmospheric transport modelling. However, atmospheric transport modelling is prone to uncertainty, and the absence of an uncertainty quantification can limit its use for detection screening. In this paper, several ensembles are assessed that could provide an atmospheric transport modelling uncertainty quantification. These ensembles are validated with radioxenon observations, and recommendations are given for atmospheric transport modelling uncertainty quantification. Finally, the added value of an ensemble for detection screening is illustrated.
- Published
- 2021
5. Use of STAX data in global-scale simulation of
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Sylvia, Generoso, Pascal, Achim, Mireille, Morin, Philippe, Gross, and Guilhem, Douysset
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Isotopes ,Air Pollutants, Radioactive ,Radiation Monitoring ,International Cooperation ,Xenon Radioisotopes - Abstract
A global-scale simulation of the
- Published
- 2021
6. Computational and experimental optimization of
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Tanner W, Hall, Meng-Jen Vince, Wang, Glenn E, Sjoden, and Matthew, Watrous
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Air Pollutants, Radioactive ,Radiation Monitoring ,International Cooperation ,Calibration ,Xenon Radioisotopes - Abstract
Here we present a new method of irradiating
- Published
- 2021
7. Production and measurement of fission product noble gases
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A.V. Davies, Robert Shearman, Steven Bell, P. H. Regan, Matthew A. Goodwin, S.M. Collins, Marc Abilama, and R. Britton
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Radioisotopes ,Radionuclide ,Nuclear fission product ,Fission products ,Fission ,Health, Toxicology and Mutagenesis ,Nuclear engineering ,chemistry.chemical_element ,General Medicine ,Uranium ,Pollution ,Noble Gases ,Neutron temperature ,chemistry ,Air Pollutants, Radioactive ,Radiation Monitoring ,Calibration ,Environmental Chemistry ,Environmental science ,Waste Management and Disposal ,Radioactive decay ,Xenon Radioisotopes - Abstract
Gaseous fission products have been produced via thermal neutron irradiation of a highly-enriched uranium target and extracted using a custom gas processing system for measurement on a prototype, high-resolution β − γ coincidence detection system. The gas was extracted and measured in two stages in order to measure the prompt and β−–delayed fission products. This paper presents an overview of the system used to produce gaseous fission products, and the results of the advanced coincidence spectrometry techniques used to identify and quantify decays from the radionuclides produced, including the noble gases 85Kr, 85mKr, 88Kr, 133Xe, 135Xe, 133mXe and 135mXe, as well as 133I and 88Rb. The measurements were validated by determination of the nuclear decay half-lives, specifically for the ground state decay of 135Xe, which was found to be 9.15(49) hours and consistent with the literature value. This work demonstrates the UK capability to produce gaseous radionuclides for quality assurance and calibration purposes in Radionuclide Laboratories supporting the Comprehensive Nuclear-Test-Ban Treaty (CTBT).
- Published
- 2021
8. Research on Three-level Enrichment Method Based on 222Rn.
- Author
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Wang Y, Shan J, Yang X, Zhang H, and Li H
- Subjects
- Xenon Radioisotopes, Charcoal, Radon
- Abstract
Abstract: Various low-concentration inert gases, including 222Rn, 133Xe, and 85Kr, pollute the atmosphere near nuclear facilities (e.g., nuclear power plants or reprocessing plants). Owing to the detection limits of instruments, it has become urgent to determine the concentration of these gases efficiently and perform their online monitoring. However, current technologies are limited by low enrichment efficiencies. In this study, a high-pressure, low-flow, large-volume, and high-efficiency adsorption method has been proposed along with a high-temperature, low-pressure, high-flow, and small-volume rapid desorption and collection method, which are based on the gas enrichment principle of activated carbon. The results demonstrated that when dynamic adsorption was implemented using a two-level enrichment method, the final desorbed gas concentration was proportional to the volume ratio of both the large and small activated carbon beds. At a volume ratio of 15:1, 222Rn concentration increased from 110 to 21,016 Bq m-3 after the two-level enrichment; meanwhile, 222Rn concentration increased from 110 to 42,012 Bq m-3 after three-level enrichment. The three-level enrichment technology provides technical support for the enrichment of low-concentration inert gases in the environment, while offering an important technical foundation for improving the monitoring of low-concentration inert gases in specific environments as well as the atmospheric environment., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2022 Health Physics Society.)
- Published
- 2023
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9. Impact of the noble gas system NEX48 in Niger on the radioxenon global network coverage for the International Monitoring System of the comprehensive nuclear-test-ban treaty
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Hamed, Abdollahnejad, Dariush, Rezaei Ochbelagh, and Majid, Azadi
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Air Pollutants, Radioactive ,Radiation Monitoring ,International Cooperation ,Health, Toxicology and Mutagenesis ,Environmental Chemistry ,Niger ,General Medicine ,Pollution ,Waste Management and Disposal ,Xenon Radioisotopes - Abstract
The radioxenon measurement components of the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) play a significant role in uncovering clandestine nuclear weapons tests. The radioxenon network coverage is a critical component of the IMS capabilities. NEX48 is one of the still to-be-certified radioxenon stations and it will be the only IMS station with radioxenon measurement capabilities in the Sahara desert in Central Africa. Therefore, it may increase the radioxenon global coverage in a vast region. Seasonal contributions from NEX48 (in Niger) on the
- Published
- 2022
10. Using STAX data to predict IMS radioxenon concentrations
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Paul W. Eslinger, Theodore W. Bowyer, Charles G. Doll, Judah I. Friese, Lori A. Metz, and Brian T. Schrom
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Isotopes ,Air Pollutants, Radioactive ,Radiation Monitoring ,Health, Toxicology and Mutagenesis ,Industry ,Environmental Chemistry ,General Medicine ,Pollution ,Waste Management and Disposal ,Xenon Radioisotopes - Abstract
The noble gas collection and measurement stations in the International Monitoring System (IMS) are heavily influenced by releases from medical isotope production facilities. The ability to reliably model the movement of radioxenon from the points of release to these IMS samplers has improved enough that a routine aspect of the analysis of IMS radioxenon data should be the prediction of the effect of releases from industrial nuclear facilities on the sample concentrations. Predicted concentrations at IMS noble gas systems in Germany and Sweden based on measured releases from Institute for Radioelements (IRE) in Belgium and atmospheric transport modeling for a four-month period are presented and discussed.
- Published
- 2022
11. SAUNA field - A sensitive system for analysis of radioxenon in soil gas samples
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T. Fritioff, Lindsay Karlkvist, A. Axelsson, Johan Kastlander, K. Elmgren, Mattias Aldener, and A. Ringbom
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Traceability ,business.industry ,Health, Toxicology and Mutagenesis ,Soil gas ,Sample (material) ,chemistry.chemical_element ,Noble gas ,General Medicine ,Pollution ,Steam Bath ,Soil ,Xenon ,chemistry ,Air Pollutants, Radioactive ,Radiation Monitoring ,Comprehensive Nuclear-Test-Ban Treaty ,Environmental Chemistry ,Environmental science ,Gas separation ,Gases ,Process engineering ,business ,Waste Management and Disposal ,Throughput (business) ,Xenon Radioisotopes - Abstract
A high throughput system for processing and detection of low levels of radioxenon in soil gas samples has been developed. Processing and analysis of sub-soil noble gas samples puts high demands on the gas separation part of the system since the samples might contain high levels of Rn, CO2 as well as other gases. The gas process is optimized to remove all CO2, H2O and Rn with a high recovery yield of the xenon in the sample to ensure a high sensitivity even for small samples. The system is designed to handle multiple samples per day with a high level of automation and sample traceability to be suitable for use in an on-site inspection (OSI) an important component in the verification of the Comprehensive Nuclear Test Ban Treaty. To ensure a rapid deployment the system could be pre-installed in a flight container.
- Published
- 2021
12. An investigation on the
- Author
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Hamed, Abdollahnejad, Dariush, Rezaei Ochbelagh, and Majid, Azadi
- Subjects
Radioisotopes ,Air Pollutants, Radioactive ,Radiation Monitoring ,International Cooperation ,Xenon Radioisotopes - Abstract
The radionuclides part of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) global network of International Monitoring System (IMS) is based on the measurement of particles and radioactive noble gases. Forty radionuclide stations are going to be equipped with radioxenon measurement components to monitor the nuclear explosion signatures around the world. Global coverage of the noble gas IMS stations has been investigated using atmospheric transport modelling. Two years of worldwide release for a hypothetical 1-kt underground nuclear explosion and detection of
- Published
- 2021
13. Source term estimation using multiple xenon isotopes in atmospheric samples
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Brian T. Schrom, Paul W. Eslinger, Justin D. Lowrey, Harry S. Miley, and W. Steven Rosenthal
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Nuclear explosion ,Pollution ,010504 meteorology & atmospheric sciences ,Health, Toxicology and Mutagenesis ,media_common.quotation_subject ,Explosions ,010501 environmental sciences ,Medical Waste ,01 natural sciences ,Synthetic data ,law.invention ,Radiation Monitoring ,law ,Nuclear power plant ,Isotopes of xenon ,Environmental Chemistry ,Waste Management and Disposal ,0105 earth and related environmental sciences ,Remote sensing ,media_common ,Radionuclide ,Isotope ,Sampling (statistics) ,Bayes Theorem ,General Medicine ,Air Pollutants, Radioactive ,Nuclear Power Plants ,Environmental science ,Radioactive Hazard Release ,Algorithms ,Xenon Radioisotopes - Abstract
Algorithms that estimate the location and magnitude of an atmospheric release using remotely sampled air concentrations typically involve a single chemical or radioactive isotope. A new Bayesian algorithm is presented that makes discrimination between possible types of releases (e.g., nuclear explosion, nuclear power plant, or medical isotope production facility) an integral part of the analysis for samples that contain multiple isotopes. Algorithm performance is demonstrated using synthetic data and correctly discriminated between most release-type hypotheses, with higher accuracy when data are available on three or more isotopes.
- Published
- 2019
14. A stilbene - CdZnTe based radioxenon detection system
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Steven A. Czyz, Harish R. Gadey, Kacey D. McGee, and Abi T. Farsoni
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010504 meteorology & atmospheric sciences ,International Cooperation ,Health, Toxicology and Mutagenesis ,Nuclear engineering ,Explosions ,chemistry.chemical_element ,010501 environmental sciences ,Scintillator ,01 natural sciences ,TRIGA ,Silicon photomultiplier ,Xenon ,Radiation Monitoring ,Stilbenes ,Environmental Chemistry ,Waste Management and Disposal ,Cdznte detector ,0105 earth and related environmental sciences ,Nuclear Weapons ,Detector ,General Medicine ,Pollution ,Zinc ,chemistry ,Air Pollutants, Radioactive ,Environmental science ,Tellurium ,Xenon Radioisotopes ,Cadmium - Abstract
Atmospheric monitoring of radioxenon is one of the most widely used methods by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) to detect elevated levels of 131mXe, 133/133mXe, and 135Xe. The ratios of these radionuclides help discriminate between peaceful use of nuclear technology and nuclear weapon explosions. Radioxenon detection systems often use plastic scintillators in the capacity of an electron detector and a gas cell, plastic gas cells are responsible for introducing high memory effect in these systems. This work presents the design of a new detection system for radioxenon monitoring that utilizes silicon photomultipliers, a stilbene gas cell, and a CdZnTe detector. This detector was evaluated using xenon radioisotope samples produced in the TRIGA reactor at Oregon State University. A 48-h background was collected and calculations of the Minimum Detectable Concentration (MDC) were carried out using the Region of Interest (ROI) approach. An MDC of less than 1 mBq/m3 was obtained for 131mXe, 133Xe, and 133mXe in accordance with the sensitivity limits set by the CTBTO and performs respectably when compared to state-of-the-art radioxenon detection systems. Using 131mXe, this study indicates that the stilbene gas cell exhibits a memory effect of 0.045 ± 0.017%, this is almost a two-order magnitude improvement compared to plastic scintillators. The primary purpose of this work is to explore the use of new stilbene detection media for radioxenon application and addressing the problem of memory effect.
- Published
- 2019
15. Source term estimation in the presence of nuisance signals
- Author
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Brian T. Schrom, Jennifer M. Mendez, and Paul W. Eslinger
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Nuclear explosion ,010504 meteorology & atmospheric sciences ,Health, Toxicology and Mutagenesis ,Explosions ,Magnitude (mathematics) ,Soil science ,010501 environmental sciences ,01 natural sciences ,Radiation Monitoring ,Environmental Chemistry ,Air Pollution, Radioactive ,Waste Management and Disposal ,0105 earth and related environmental sciences ,Nuclear Weapons ,Radionuclide ,Isotope ,business.industry ,General Medicine ,Nuclear power ,Pollution ,Term (time) ,Air Pollutants, Radioactive ,Environmental science ,business ,Nuisance ,Algorithms ,Xenon Radioisotopes - Abstract
Many source-term estimation algorithms for atmospheric releases assume the measured concentration data are influenced only by the releases of interest. However, there are situations where identifying a short-term release from an unknown location in the presence of long-term releases from a different location is of interest. One such example is determining if part or all of a typical magnitude concentration of a radioactive isotope in a sampler came from a nuclear explosion, such as the explosion announced by DPRK in 2013, while medical isotope facilities and nuclear power plants were also operating in the region. An estimation algorithm has been developed for the case where a short-duration release is confounded by a long-term nuisance signal associated with an additional release location. The technique is demonstrated using synthetic release data for a hypothetical medical isotope production facility and a hypothetical puff release from a different location. The algorithm successfully determines the location (within 30 km) and time-varying release rate (within a factor of 2) for the medical isotope production facility and the location (within 60 km), time (within 6 h), and release magnitude (within a factor of 4) of the puff release.
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- 2019
16. Radon removal trap design and coefficient testing for the development of an effective radioxenon sampling, separation and measurement system
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Xiaolong Yu, Guoqing Zhou, Xinhua Zhao, Dingwei Huang, Ziwei Cheng, Zining Tian, Shujuan Feng, and Chongyang Zhou
- Subjects
010504 meteorology & atmospheric sciences ,Health, Toxicology and Mutagenesis ,chemistry.chemical_element ,Radon ,010501 environmental sciences ,01 natural sciences ,Xenon ,Adsorption ,Radiation Monitoring ,Environmental Chemistry ,Waste Management and Disposal ,0105 earth and related environmental sciences ,Isotope ,System of measurement ,Radiochemistry ,Sampling (statistics) ,General Medicine ,Trap (plumbing) ,Pollution ,chemistry ,Air Pollutants, Radioactive ,Environmental science ,Enrichment factor ,Bismuth ,Xenon Radioisotopes - Abstract
To monitor low-level radioxenon isotopes activity concentrations in the bulk gases, a radioxenon sampling, separation and measurement system has been developed. The xenon enrichment factor of this system is more than 105 after the separation of impurities, including N2, O2, CO2and H2O, as well as radon and its progenies, such as 214Pb and 214Bi. Since radon and its progenies interfere with radioxenon measurement, they have to be removed before radioxenon counting. To separate radon from xenon, different dynamic adsorption coefficients of xenon and radon are used to design small radon removal trap to retain radon after eluting xenon, and the ratio between radon and xenon dynamic adsorption coefficient gives the adsorbent weight relationship between the xenon adsorption trap and its related radon removal trap. To test the effectiveness of radon removal, the relative measuring method is used by measuring γ-rays energies of radon progenies in canister filling with either the measuring sample prepared by the system or the original gas. The results show that the radon removal coefficient and the stable xenon recovery, which are two important parameters in the radioxenon system, are at the order of 10-6 and >70% respectively. These meet the specifications proposed by the Comprehensive Nuclear-Test-Ban Treaty Organization.
- Published
- 2019
17. Next-generation particulate monitoring
- Author
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R. Britton and A.V. Davies
- Subjects
Radioisotopes ,Nuclear Weapons ,Radiation ,Air Pollutants, Radioactive ,Radiation Monitoring ,Reproducibility of Results ,Dust ,Xenon Radioisotopes - Abstract
Operated by the Comprehensive Nuclear-Test-Ban Treaty Organisation, the International Monitoring System is used by almost 200 nations to monitor for nuclear weapons tests. The IMS is still under development, and the Comprehensive Nuclear-Test-Ban Treaty has not yet entered into force, however the radionuclide component has proved instrumental in radically changing both nuclear verification science and researchers' understanding of the dynamic global radiation background. After more than 20 years, the network is mostly complete, however the technology utilised for the particulate monitoring component remains practically the same, despite a number of laboratories developing coincidence systems that can offer orders of magnitude improvements in detection sensitivity and reliability. This paper describes the status of the technology, and the advantages of implementing this within the International Monitoring System. Furthermore, the performance of a prototype system developed by the Comprehensive Nuclear-Test-Ban Treaty Organisation is presented, and the implications of introducing this technology considered.
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- 2022
18. Evaluation of several relevant fractionation processes as possible explanation for radioxenon isotopic activity ratios in samples taken near underground nuclear explosions in shafts and tunnels
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S. Michelle Bourret, Edward M. Kwicklis, and Philip H. Stauffer
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Radioisotopes ,Radionuclide ,Atmosphere ,Health, Toxicology and Mutagenesis ,Condensation ,Mineralogy ,chemistry.chemical_element ,Explosions ,General Medicine ,Fractionation ,Pollution ,Isotope fractionation ,Xenon ,chemistry ,Air Pollutants, Radioactive ,Radiation Monitoring ,Isotopes of xenon ,Environmental Chemistry ,Environmental science ,Chimney ,Waste Management and Disposal ,Xenon Radioisotopes - Abstract
Gas samples taken from two historic underground nuclear tests done in 1989 at the Nevada National Security Site (NNSS), formerly the Nevada Test Site (NTS), were examined to determine how xenon isotopes fractionate because of early-time cavity processes, transport through the rock, or dispersal through tunnels. Xenon isotopes are currently being used to distinguish civilian sources of xenon in the atmosphere from sources associated with underground nuclear explosions (UNEs). The two nuclear tests included (1) BARNWELL, a test conducted in a vertical shaft approximately 600 m below ground surface at Pahute Mesa, and (2) DISKO ELM, a horizontal line-of-sight test done in P-tunnel approximately 261 m below the surface of Aqueduct Mesa. Numerical flow and transport models developed for the two sites had mixed success when attempting to match the observed xenon isotope ratios. At the BARNWELL site, the simulated xenon isotope ratios were consistent with measurements from the chimney and ground surface, and appeared to have been affected primarily by fractionation during subsurface transport. At the DISKO ELM site, samples taken from two elevations in the chimney failed to show the degree of fractionation predicted by the models during transport, and did not show evidence for significant fractionation due to early-time condensation of refractory xenon-precursor radionuclides into the melt glass. Gas samples taken from the adjacent tunnels in the days following the test showed mixed evidence for early-time separation of xenon isotopes from their iodine precursors.
- Published
- 2021
19. Modeling of fission and activation products in molten salt reactors and their potential impact on the radionuclide monitoring stations of the International Monitoring System
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Cheslan K. Simpson, Christine Johnson, Johnathan L. Slack, J. L. Burnett, and Manish K. Sharma
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010504 meteorology & atmospheric sciences ,Health, Toxicology and Mutagenesis ,Nuclear engineering ,Shutdown ,010501 environmental sciences ,01 natural sciences ,law.invention ,Iodine Radioisotopes ,chemistry.chemical_compound ,Isotopes ,law ,Radiation Monitoring ,Environmental Chemistry ,Boiling water reactor ,Molten salt ,Waste Management and Disposal ,0105 earth and related environmental sciences ,Fission products ,Molten salt reactor ,FLiBe ,Pressurized water reactor ,General Medicine ,Pollution ,chemistry ,Air Pollutants, Radioactive ,Generation IV reactor ,Environmental science ,Xenon Radioisotopes - Abstract
Molten Salt Reactors (MSRs) are one of six Generation IV reactor designs currently under development around the world. Because of the unique operating conditions of MSRs, which include molten fuel and the continuous removal of gaseous fission products during operation, work was performed to model the production of activation and fission products and analyze the potential impact of emissions on the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Simulations were performed to predict the production of IMS-relevant radionuclides in four MSR designs operating under two scenarios: (1) a sealed reactor with releases only during operational shutdown, and (2) continuous reprocessing or sparging of the fuel salt. From these production estimates the radioxenon and radioiodine signatures were extracted and compared to three current reactor designs (Boiling Water Reactor, Pressurized Water Reactor, High-Power Channel-Type Reactor). In cases where continuous reprocessing of the fuel salt occurred, both the radioxenon and radioiodine signatures were nearly indistinguishable from a nuclear explosion. Estimates were also made of the potential emission rate of radioxenon for three reactor designs and it was found that MSRs have the potential to emit radioxenon isotopes at a rate of 10 15 − 8 × 10 16 Bq/d for 133Xe, which may adversely affect nuclear explosion monitoring, if no abatement is used. An assessment was made of activation products using a candidate fuel salt (FLiBe) mixed with corrosion products for the Thorium Molten Salt Reactor (TMSR-LF1).
- Published
- 2021
20. Analysis of environmental radioxenon detections in the UK
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A.V. Davies, Matthew A. Goodwin, and R. Britton
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Radionuclide ,010504 meteorology & atmospheric sciences ,Health, Toxicology and Mutagenesis ,Monitoring system ,General Medicine ,010501 environmental sciences ,01 natural sciences ,Pollution ,United Kingdom ,Operational system ,Belgium ,Air Pollutants, Radioactive ,Radiation Monitoring ,Environmental Chemistry ,Environmental science ,Nuclear test ,Waste Management and Disposal ,National data ,Xenon Radioisotopes ,0105 earth and related environmental sciences ,Remote sensing - Abstract
Radioxenon activity concentrations are monitored globally using the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organisation, improving the monitoring community's ability to detect radionuclide signatures from an underground nuclear test (UNT). An IMS-like noble gas system is in operation at AWE (Aldermaston, UK) and can collect and measure radioxenon isotopes in environmental air samples. When operated in this mode, data produced is analysed at the UK National Data Centre (NDC) and significant detection events are flagged for further investigation. This work discusses a number of significant detection events analysed using the operational system deployed at the UK NDC, which includes atmospheric transport simulations and a real-time stack-monitoring data feed from the nearest medical isotope production facility in Belgium. A comparison of the expected radionuclide contributions with measured detections is presented, including a comparison of the isotopic ratios for the radioxenon isotopes of interest (133Xe, 131mXe, 133mXe, 135Xe).
- Published
- 2020
21. Multi-nuclide source term estimation method for severe nuclear accidents from sequential gamma dose rate based on a recurrent neural network
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Qing Shan, Xiaojun Zhang, Qi Yue, Yongsheng Ling, Wenbao Jia, Tian Huang, and Daqian Hei
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Environmental Engineering ,Health, Toxicology and Mutagenesis ,0211 other engineering and technologies ,02 engineering and technology ,010501 environmental sciences ,01 natural sciences ,Least squares ,Iodine Radioisotopes ,Radiation Monitoring ,Environmental Chemistry ,Nuclide ,Waste Management and Disposal ,0105 earth and related environmental sciences ,021110 strategic, defence & security studies ,Radionuclide ,business.industry ,Bayesian optimization ,Bayes Theorem ,Atmospheric dispersion modeling ,Nuclear power ,Pollution ,Mean absolute percentage error ,Recurrent neural network ,Air Pollutants, Radioactive ,Cesium Radioisotopes ,Nuclear Power Plants ,Environmental science ,Neural Networks, Computer ,business ,Radioactive Hazard Release ,Algorithm ,Xenon Radioisotopes - Abstract
When severe nuclear accidents at nuclear power plants release radioactive material into the atmosphere, the source term information is typically unknown. Estimating the emission rate of radionuclides is essential to assess the consequences of the accident before adequate decision-making can be performed. A recurrent neural network-based model, optimized with the Bayesian method, is proposed to estimate the emission rates of multi-nuclides using off-site sequential gamma dose rate monitoring data. Compared with the existing method that is based on least squares, this new model does not require a priori information and the complicated and time-consuming process of conducting atmospheric dispersion simulations following a nuclear accident, which is conducive to a faster response. Six typical radionuclides (Sr-91, La-140, Te-132, Xe-133, I-131, and Cs-137) were set as mixed source terms, combined with meteorological parameters, and input into the International Radiological Assessment System for simulation to generate data sets for model training. The results indicate that with the input of data describing the sequential gamma dose rate, the accuracy of the nuclide emission rates estimated by this new method is continuously improved, with a mean absolute percentage error for Te-132 of below 7% over 10 h.
- Published
- 2020
22. Improving the estimation accuracy of multi-nuclide source term estimation method for severe nuclear accidents using temporal convolutional network optimized by Bayesian optimization and hyperband
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Yongsheng Ling, Tian Huang, Qi Yue, Qing Shan, Daqian Hei, Xiaojun Zhang, Chao Shi, and Wenbao Jia
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Iodine Radioisotopes ,Cesium Radioisotopes ,Radiation Monitoring ,Health, Toxicology and Mutagenesis ,Environmental Chemistry ,Bayes Theorem ,General Medicine ,Radioactive Hazard Release ,Pollution ,Waste Management and Disposal ,Xenon Radioisotopes - Abstract
During a nuclear accident, estimating the source terms using environmental measurements is vital for emergency decision-making. In this study, we propose a forecasting model based on a temporal convolutional network to estimate the release rates of seven radionuclides (Kr-88, Te-132, I-131, Xe-133, Cs-137, Ba-140, and Ce-144) based on off-site sequential gamma dose rates and meteorological monitoring data. To determine the best structure of the neural network, Bayesian optimization and hyperband (BOHB) was used on the hyperparameters of the model to reduce the testing loss. Additionally, a gradient boosting regression model was used to predict missing gamma dose rates to ensure the model offers a relatively reliable estimate under certain circumstances. The international radiological assessment system (InterRAS) was used to generate datasets for model training and testing. The results showed that the optimal hyperparameters selected by BOHB can reduce the valid loss of the model to 0.0153, and the mean absolute percentage error of prediction for the seven radionuclides was below 12%, three of which (Kr-88, Te-132, Cs-137) reached 8% at 10 h. When the first and second time-steps of the data were missing, the mean absolute percentage error of the prediction for all radionuclides was less than 30% after using a gradient boosting regression.
- Published
- 2022
23. Modelling of a Single-Channel Beta-Gamma Coincidence Phoswich Detector Using Geant4 for the Conversion Electron Energy Peak Resolution and Beta-Gamma Coincidence Efficiency Improvement.
- Author
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Zhang, Weihua, Mekarski, Pawel, Bean, Marc, Yi, Jing, and Ungar, Kurt
- Subjects
BETA rays ,GAMMA rays ,ELECTRON energy states ,PHOTOMULTIPLIERS ,MONTE Carlo method ,XENON isotopes - Abstract
In this study, an optimized single-channel phoswich well detector design has been proposed and assessed in order to improve beta-gamma coincidence measurement sensitivity of xenon radioisotopes. This newly designed phoswich well detector consists of a plastic beta counting cell (BC404) embedded in a CsI (Tl) crystal coupled to a photomultiplier tube. The BC404 is configured in a cylindrical pipe shape to minimise light collection deterioration. The CsI (Tl) crystal consists of a rectangular part and a semi-cylinder scintillation part as a light reflector to increase light gathering. Compared with a PhosWatch detector, the final optimized detector geometry showed 15 % improvement in the energy resolution of a Xe 129.4 keV conversion electron peak. The predicted beta-gamma coincidence efficiencies of xenon radioisotopes have also been improved accordingly. [ABSTRACT FROM AUTHOR]
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- 2014
- Full Text
- View/download PDF
24. Measurement of radioxenon and radioargon in soil gas collected in the region of Kvarntorp, Sweden
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C. Söderström, M. Aldener, Roland Purtschert, A. Axelsson, Johan Kastlander, T. Fritioff, and A. Ringbom
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010504 meteorology & atmospheric sciences ,Soil test ,530 Physics ,Health, Toxicology and Mutagenesis ,Field experiment ,chemistry.chemical_element ,Radon ,Soil science ,010501 environmental sciences ,01 natural sciences ,Soil ,Radiation Monitoring ,Environmental Chemistry ,Soil Pollutants, Radioactive ,Waste Management and Disposal ,0105 earth and related environmental sciences ,Sweden ,Soil gas ,General Medicine ,Pollution ,chemistry ,Air Pollutants, Radioactive ,Environmental science ,Sample collection ,Gases ,Dose rate ,Xenon Radioisotopes - Abstract
Over 40 soil gas samples were collected both in post-industrial areas as well as in undisturbed areas in the region of Kvarntorp, Sweden. Radioxenon (133Xe) was detected in 15 samples and radioargon was detected in 7 from 10 samples analysed. The concentration of radioxenon and radioargon in soil gas ranged up to 109 mBq/m3 and 19 mBq/m3, respectively. During sample collection other soil gases such as radon, CO2 and O2 were also measured and soil samples were taken along with dose rate measurements. The field experiment presented here shows that it is possible to detect naturally occurring radioxenon and radioargon in soil gas simultaneously.
- Published
- 2020
25. 6 months of radioxenon detection in western Europe with the SPALAX-New generation system - Part 2: Atmospheric transport modelling
- Author
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S. Generoso, Pascal Achim, Sylvain Topin, Mireille Morin, P. Gross, Gilbert Le Petit, Marguerite Monfort, Christophe Moulin, G. Douysset, CEA- Saclay (CEA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), DAM Île-de-France (DAM/DIF), Direction des Applications Militaires (DAM), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
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010504 meteorology & atmospheric sciences ,Spalax ,Health, Toxicology and Mutagenesis ,[SDV]Life Sciences [q-bio] ,010501 environmental sciences ,Atmospheric sciences ,01 natural sciences ,Prevailing winds ,Air pollutants ,Belgium ,Radiation Monitoring ,Environmental Chemistry ,Animals ,Waste Management and Disposal ,0105 earth and related environmental sciences ,Family Characteristics ,biology ,Family characteristics ,General Medicine ,biology.organism_classification ,Pollution ,Europe ,Air Pollutants, Radioactive ,Western europe ,Environmental science ,Nuclear test ,Xenon Radioisotopes - Abstract
International audience; Atmospheric transport modeling has been used to interpret the unprecedented number of multi-isotope detections of radioxenons observed during the six months of the qualification process by the Comprehensive Nuclear-Test-Ban Treaty Organization of the new SPALAX-NG system (Système de Prélèvement Automatique en Ligne avec l’Analyse du Xénon - Nouvelle Génération). Highest $^{133}$Xe activity concentrations were found to be systematically associated with the concomitant measurement of several other radioxenons at the prevailing wind direction of north/northeast pointing to the Institute for Radio Elements (IRE), a medical isotope production facility located in Fleurus (Belgium). The lowest $^{133}$Xe activity concentrations were not associated with a prevailing wind direction or other radioxenons, indicating the contribution of distant sources (global background). The IRE's average source terms for $^{133}$mXe and to a lesser extent for $^{133}$Xe (slightly overestimated by a factor of 1.7) showed good agreement with the literature values, while corrections by a factor of ~23 and ~53 were proposed for $^{131}$mXe and $^{135}$Xe since the initial values were underestimated. However, detections of $^{131}$mXe alone and some low-activity concentrations of $^{133}$Xe associated with only one of the other radioxenons could not be linked to the IRE releases. Analysis of these cases suggests the contribution of local source releases that have been difficult to identify to date. In addition to the global background, releases from such local sources, if not identified, could affect the analysis of the isotopic ratios measured following a nuclear test. The characterization of these local contributions is now possible owing to the capacity of the SPALAX-NG and other new generation measurements systems.
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- 2020
26. 6 months of radioxenon detection in western Europe with the SPALAX-New generation system - Part1: Metrological capabilities
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P. Gross, Mireille Morin, Christophe Moulin, Gilbert Le Petit, S. Generoso, G. Douysset, Sylvain Topin, A. Cagniant, Pascal Achim, Jean-Pierre Fontaine, Thomas Philippe, O. Delaune, CEA- Saclay (CEA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), DAM Île-de-France (DAM/DIF), Direction des Applications Militaires (DAM), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
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Nuclear explosion ,010504 meteorology & atmospheric sciences ,Spalax ,Health, Toxicology and Mutagenesis ,[SDV]Life Sciences [q-bio] ,Data reliability ,010501 environmental sciences ,01 natural sciences ,Radiation Monitoring ,Environmental Chemistry ,Animals ,Waste Management and Disposal ,0105 earth and related environmental sciences ,Remote sensing ,Family Characteristics ,biology ,Reproducibility of Results ,General Medicine ,biology.organism_classification ,Pollution ,Data availability ,Metrology ,Europe ,Air Pollutants, Radioactive ,Western europe ,Environmental science ,Nuclear test ,France ,Xenon Radioisotopes - Abstract
International audience; The SPALAX-NG is a new-generation system that is designed to detect radioactive xenon at trace levels in the atmosphere following a nuclear explosion or civilian source release. This new system formed part of a validation program led by the Provisional Technical Secretary of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) Organization. In this study, the first SPALAX-NG unit was tested for six months between October 2018 and April 2019 at the CEA/DIF premises near Paris, France. This test period provided an outstanding opportunity to illustrate the high level of detectability and reliability of the system. The data availability obtained over this period was approximately 99%, which was well above the CTBT Data Availability criteria of 95%. The data reliability was demonstrated by a comparison with a collocated SPALAX-1 unit (former version of SPALAX) and by re-measuring several samples at the CTBT-certified French laboratory FRL08. The high sensitivity to the detection of the four relevant radioxenon isotopes was fully demonstrated and enabled the recording of a major dataset for western Europe. A large set of isotopic ratios was measured, which enabled the discrimination criteria between civilian sources and nuclear test signatures to be refined.
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- 2020
27. A prototype detection system for atmospheric monitoring of xenon radioisotopes
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Lily Ranjbar, Steven A. Czyz, and Abi T. Farsoni
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Physics ,Nuclear and High Energy Physics ,Xenon Radioisotopes ,Readout electronics ,010501 environmental sciences ,Scintillator ,010403 inorganic & nuclear chemistry ,01 natural sciences ,Coincidence ,Spectral line ,0104 chemical sciences ,Low noise ,Nuclear physics ,Beta gamma coincidence ,Instrumentation ,0105 earth and related environmental sciences ,Coincidence detection in neurobiology - Abstract
The design of a radioxenon detection system utilizing a CdZeTe crystal and a plastic scintillator coupled to an array of SiPMs to conduct beta-gamma coincidence detection for atmospheric radioxenon monitoring, as well as the measurement of 135Xe and 133∕133m Xe, have been detailed previously. This paper presents recent measurements of 133∕133m Xe and 131m Xe and the observation of conversion electrons in their coincidence spectra, as well as a 48-hour background measurement to calculate the Minimum Detectable Concentration (MDC) of radioxenon isotopes in the system. The identification of Regions of Interest (ROIs) in the coincidence spectra yielded from the radioxenon measurements, and the subsequent calculation of the MDCs of the system for 135Xe, 133∕133m Xe, and 131m Xe, are also discussed. Calculated MDCs show that the detection system preforms respectably when compared to other state of the art radioxenon detection systems and achieved an MDC of less than 1 mBq/m 3 for 131m Xe, 133Xe, and 133m Xe, in accordance with limits set by the Comprehensive Nuclear-Test-Ban Treaty (CTBTO). The system also provides the advantage of room temperature operation, compactness, low noise operation and having simple readout electronics.
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- 2018
28. Extraction and quantification system for environmental radioxenon sample analysis
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M. Haji-Hosseini, M.N. Nasrabadi, and M. Sabzian
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Granular activated carbon ,Materials science ,Health, Toxicology and Mutagenesis ,chemistry.chemical_element ,010403 inorganic & nuclear chemistry ,01 natural sciences ,Column (database) ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,Adsorption ,Xenon ,Radiation Monitoring ,Environmental Chemistry ,Waste Management and Disposal ,Packed bed ,Chromatography ,Extraction (chemistry) ,General Medicine ,Pollution ,Sample (graphics) ,0104 chemical sciences ,chemistry ,Air Pollutants, Radioactive ,Gas chromatography ,Xenon Radioisotopes - Abstract
A xenon dynamic adsorption setup based on granular activated carbon packed column was developed. The adsorption behavior of xenon under different experimental conditions was studied and the results used to design an appropriate adsorber column for specific conditions. The resulting radioxenon gas extraction and quantification setup was evaluated based on an inter-comparison exercise and standard sample analysis results. The results showed that the quantification setup achieves experimental rules with uncertainty of ±3%.
- Published
- 2018
29. A Method for Identification and Assessment of Radioxenon Plumes by Absorption in Polycarbonates
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Dobromir Pressyanov and Pavel Stavrev
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Makrofol ,Polycarboxylate Cement ,retrospective estimates ,Chemical technology ,TP1-1185 ,133Xe ,absorption in polycarbonates ,Biochemistry ,Article ,Atomic and Molecular Physics, and Optics ,Analytical Chemistry ,radioxenon plumes ,nuclear accidents ,Air Pollutants, Radioactive ,Radiation Monitoring ,Electrical and Electronic Engineering ,Instrumentation ,Xenon Radioisotopes ,Retrospective Studies - Abstract
A method for the retrospective evaluation of the integrated activity concentration of 133Xe during radioxenon plumes and the moment of the plume’s center is proposed and explored by computer modeling. The concept is to use a specimen of polycarbonate material (a stack of Makrofol N foils of thickness 120 µm and 40 µm in 1 L non-hermetic Marinelly beaker) that is placed in the environment or in a controlled nuclear or radiopharmaceutical facility. On a regular basis or incidentally, the specimen may be retrieved and gamma spectrometry in two consecutive time intervals with durations of 8 h and 16 h is performed. To assess the performance of the method, 133Xe plumes of various integrated activity concentrations and with a duration of up to 10 h are simulated and analyzed, assuming that the measurement starts with a delay of up to one day after the moment of the plume center. It is found that the deviation between the estimates by the method and their true values are within a few percent. Depending on the delay, events of integrated 133Xe activity concentration 250–1000 Bq h m−3 might be qualitatively identified. At levels >10,000 Bq h m−3, the uncertainty of the quantitative estimates might be ≤10%.
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- 2021
30. Classification of radioxenon spectra with deep learning algorithm
- Author
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Sepideh Alsadat Azimi, Hossein Afarideh, Abdelhakim Gheddou, Jong-Seo Chai, Radek Hofman, and Martin Kalinowski
- Subjects
business.industry ,Computer science ,Health, Toxicology and Mutagenesis ,Deep learning ,Pattern recognition ,General Medicine ,Noble gas (data page) ,Pollution ,Convolutional neural network ,Coincidence ,Spectral line ,Deep Learning ,Categorization ,Air Pollutants, Radioactive ,Radiation Monitoring ,Environmental Chemistry ,Review process ,Neural Networks, Computer ,Artificial intelligence ,business ,Waste Management and Disposal ,Xenon Radioisotopes - Abstract
In this study, we propose for the first time a model of classification for Beta-Gamma coincidence radioxenon spectra using a deep learning approach through the convolution neural network (CNN) technique. We utilize the entire spectrum of actual data from a noble gas system in Charlottesville (USX75 station) between 2012 and 2019. This study shows that the deep learning categorization can be done as an important pre-screening method without directly involving critical limits and abnormal thresholds. Our results demonstrate that the proposed approach of combining nuclear engineering and deep learning is a promising tool for assisting experts in accelerating and optimizing the review process of clean background and CTBT-relevant samples with high classification average accuracies of 92% and 98%, respectively.
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- 2021
31. Possible impacts of molten salt reactors on the International Monitoring System
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Justin I. McIntyre, Paul W. Eslinger, Cheslan K. Simpson, J. L. Burnett, Johnathan L. Slack, and Christine Johnson
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010504 meteorology & atmospheric sciences ,Health, Toxicology and Mutagenesis ,010501 environmental sciences ,01 natural sciences ,law.invention ,Liquid fuel ,Isotopes ,Nuclear Reactors ,Radiation Monitoring ,law ,Nuclear power plant ,Breeder reactor ,Environmental Chemistry ,Waste Management and Disposal ,Sparging ,0105 earth and related environmental sciences ,Waste management ,business.industry ,General Medicine ,Nuclear power ,Solid fuel ,Pollution ,Electricity generation ,Air Pollutants, Radioactive ,Nuclear fission ,Nuclear Power Plants ,Environmental science ,business ,Xenon Radioisotopes - Abstract
Molten salt reactors (MSRs) are gaining support as many countries look for ways to increase power generation and replace aging nuclear energy production facilities. MSRs have inherently safe designs, are scalable in size, can burn transuranic wastes from traditional solid fuel nuclear reactors, can store excess heat in thermal reservoirs for water desalination, and can be used to produce medical isotopes as part of the real-time liquid-fuel recycling process. The ability to remove 135Xe in real time from the fuel improves the power production in an MSR because 135Xe is the most significant neutron-absorbing isotope generated by nuclear fission. Xenon-135, and other radioactive gases, are removed by sparging the fuel with an inert gas while the liquid fuel is recirculated from the reactor inner core through the heat exchangers. Without effective abatement technologies, large amounts of radioactive gas could be released during the sparging process. This work examines the potential impact of radioxenon releases on samplers used by the International Monitoring System (IMS) to detect nuclear explosions. Atmospheric transport simulations from seven hypothetical MSRs on different continents were used to evaluate the holdup time needed before release of radioxenon so IMS samplers would register few detections. Abatement technologies that retain radioxenon isotopes for at least 120 d before their release will be needed to mitigate the impacts from a molten salt breeder reactor used to replace a nuclear power plant. A holdup time of about 150 d is needed to reduce emissions to the average level of current nuclear power plants.
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- 2021
32. Comparison of near-background concentrations of Argon-37 and Xenon-133 in the atmosphere
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Brad G. Fritz, ThomasR. Alexander, VincentT. Woods, TheodoreW. Bowyer, EmilyK. Mace, and JamesC. Hayes
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Nuclear explosion ,Atmospheric air ,010504 meteorology & atmospheric sciences ,Health, Toxicology and Mutagenesis ,chemistry.chemical_element ,010501 environmental sciences ,Atmospheric sciences ,01 natural sciences ,Atmosphere ,Xenon ,Radiation Monitoring ,Isotopes of xenon ,Environmental Chemistry ,Argon ,Waste Management and Disposal ,0105 earth and related environmental sciences ,Radioisotopes ,Background concentrations ,Monitoring system ,General Medicine ,Pollution ,chemistry ,Air Pollutants, Radioactive ,Environmental science ,Xenon Radioisotopes - Abstract
Radioisotopes of the noble gases xenon and argon can be important indicators of underground nuclear explosions. The Comprehensive Nuclear-Test-Ban Treaty (CTBT) includes monitoring capabilities to identify potential nuclear explosions conducted in violation of the CTBT. This monitoring currently focuses on measurement of the xenon isotopes 131mXe, 133Xe, 133mXe, and 135Xe. However, it is predicted that within 100 days of an underground nuclear explosion (UNE) 37Ar would be released to the atmosphere at higher concentrations than xenon and with a higher signal to background ratio, depending on the radioxenon background levels. Therefore, inclusion of 37Ar measurement capabilities at atmospheric International Monitoring System (IMS) stations may represent an improvement in the capability to detect a nuclear explosion. At an IMS station location, an understanding of the expected range of background 37Ar activity concentrations is critical to determining what levels would constitute an elevated concentration. This work describes our analysis of atmospheric samples for 37Ar to evaluate the range of background concentrations. Samples were collected at multiple locations withing the United States, with approximately half coming from a sampler co-located with an IMS xenon monitoring station (RN75). The range of 37Ar concentrations measured in atmospheric air samples was relatively narrow; for samples considered detectable, the minimum and maximum measured concentrations were 0.56 and 2.3 mBq/m3, respectively. Comparison of 37Ar and 133Xe concentrations measured at the IMS station indicated some correlation between the measured concentrations. The results presented here demonstrate the capability to detect background concentrations of 37Ar in atmospheric air and provide a basis for potential implementation of 37Ar monitoring at IMS stations.
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- 2021
33. Decision trees for optimizing the minimum detectable concentration of radioxenon detectors
- Author
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John L. Orrell, R. Saldanha, B. Loer, and A. Hagen
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010504 meteorology & atmospheric sciences ,Computer science ,Health, Toxicology and Mutagenesis ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Decision tree ,chemistry.chemical_element ,Radon ,010501 environmental sciences ,Interference (wave propagation) ,01 natural sciences ,Particle detector ,Radiation Monitoring ,Environmental Chemistry ,Sensitivity (control systems) ,Waste Management and Disposal ,0105 earth and related environmental sciences ,Decision Trees ,Detector ,General Medicine ,Pollution ,chemistry ,Air Pollutants, Radioactive ,Metric (mathematics) ,Algorithm ,Xenon Radioisotopes ,Energy (signal processing) - Abstract
We present a novel application of machine learning techniques to optimize the design of a radiation detection system. A decision tree-based algorithm is described which greedily optimizes partitioning of energy depositions based on a minimum detectable concentration metric – appropriate for radiation measurement. We apply this method to the task of optimizing sensitivity to radioxenon decays in the presence of a high rate of radon-progeny backgrounds (i.e., assuming no physical radon removal by traditional gas separation techniques). Assuming other backgrounds are negligible, and considering sensitivity to each xenon isotope separately (neglecting interference between isotopes), we find that, in general, high resolution readout and high spatial segmentation yield little additional capability to discriminate against radon backgrounds compared to simpler detector designs.
- Published
- 2021
34. MCNPX CALCULATIONS OF SPECIFIC ABSORBED FRACTIONS IN SOME ORGANS OF THE HUMAN BODY DUE TO APPLICATION OF 133Xe, 99mTc and 81mKr RADIONUCLIDES
- Author
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Dragoslav Nikezic, Zoran Jovanovic, J.M. Gómez Ros, Paolo Ferrari, Dragana Krstic, and Ferrari, P.
- Subjects
Models, Anatomic ,Organs at Risk ,Radionuclide ,Radiation ,Materials science ,Radiological and Ultrasound Technology ,Monte Carlo method ,Radiochemistry ,Public Health, Environmental and Occupational Health ,Technetium ,Krypton Radioisotopes ,General Medicine ,Whole-Body Counting ,Imaging phantom ,030218 nuclear medicine & medical imaging ,3. Good health ,03 medical and health sciences ,0302 clinical medicine ,030220 oncology & carcinogenesis ,Body Burden ,Humans ,Computer Simulation ,Radiology, Nuclear Medicine and imaging ,Monte Carlo Method ,Xenon Radioisotopes - Abstract
Monte Carlo simulations were performed to evaluate treatment doses with wide spread used radionuclides 133Xe, 99mTc and 81mKr. These different radionuclides are used in perfusion or ventilation examinations in nuclear medicine and as indicators for cardiovascular and pulmonary diseases. The objective of this work was to estimate the specific absorbed fractions in surrounding organs and tissues, when these radionuclides are incorporated in the lungs. For this purpose a voxel thorax model has been developed and compared with the ORNL phantom. All calculations and simulations were performed by means of the MCNP5/X code. © The Author 2017. Published by Oxford University Press. All rights reserved.
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- 2017
35. Long-range transport of Xe-133 emissions under convective and non-convective conditions
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Emmy Hoffmann, J. Kuśmierczyk-Michulec, Martin Kalinowski, Jonathan Baré, and Monika Krysta
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Convection ,010504 meteorology & atmospheric sciences ,Meteorology ,Release point ,Health, Toxicology and Mutagenesis ,chemistry.chemical_element ,010502 geochemistry & geophysics ,Atmospheric sciences ,01 natural sciences ,Xenon ,Radiation Monitoring ,Range (statistics) ,Environmental Chemistry ,Dispersion (water waves) ,Waste Management and Disposal ,Trajectory (fluid mechanics) ,Air mass ,0105 earth and related environmental sciences ,Radionuclide ,Australia ,General Medicine ,Models, Theoretical ,Pollution ,chemistry ,Air Pollutants, Radioactive ,Environmental science ,Radiopharmaceuticals ,Xenon Radioisotopes - Abstract
To investigate the transport of xenon emissions, the Provisional Technical Secretariat (PTS) operates an Atmospheric Transport Modelling (ATM) system based on the Lagrangian Particle Dispersion Model FLEXPART. The air mass trajectory ideally provides a "link" between a radionuclide release and a detection confirmed by radionuclide measurements. This paper investigates the long-range transport of Xe-133 emissions under convective and non-convective conditions, with special emphasis on evaluating the changes in the simulated activity concentration values due to the inclusion of the convective transport in the ATM simulations. For that purpose a series of 14 day forward simulations, with and without convective transport, released daily in the period from 1 January 2011 to 30 June 2013, were analysed. The release point was at the ANSTO facility in Australia. The simulated activity concentrations for the period January 2011 to February 2012 were calculated using the daily emission values provided by the ANSTO facility; outside the aforementioned period, the median daily emission value was used. In the simulations the analysed meteorological input data provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) were used with the spatial resolution of 0.5°. It was found that the long-range transport of Xe-133 emissions under convective conditions, where convection was included in the ATM simulation, led to a small decrease in the activity concentration, as compared to transport without convection. In special cases related to deep convection, the opposite effect was observed. Availability of both daily emission values and measured Xe-133 activity concentration values was an opportunity to validate the simulations. Based on the paired t-test, a 95% confidence interval for the true mean difference between simulations without convective transport and measurements was constructed. It was estimated that the overall uncertainty lies between 0.08 and 0.25 mBq/m3. The uncertainty for the simulations with the convective transport included is slighted shifted to the lower values and is in the range between 0.06 and 0.20 mBq/m3.
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- 2017
36. 135Xe measurements with a two-element CZT-based radioxenon detector for nuclear explosion monitoring
- Author
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Abi T. Farsoni, Lily Ranjbar, and E. M. Becker
- Subjects
Physics ,Nuclear explosion ,Health, Toxicology and Mutagenesis ,Nuclear engineering ,Detector ,Xenon Radioisotopes ,General Medicine ,010502 geochemistry & geophysics ,010403 inorganic & nuclear chemistry ,01 natural sciences ,Pollution ,Czt detector ,Coincidence ,0104 chemical sciences ,TRIGA ,Nuclear physics ,Beta gamma coincidence ,Environmental Chemistry ,Waste Management and Disposal ,0105 earth and related environmental sciences - Abstract
Measurement of elevated concentrations of xenon radioisotopes (131mXe, 133mXe, 133Xe and 135Xe) in the atmosphere has been shown to be a very powerful method for verifying whether or not a detected explosion is nuclear in nature. These isotopes are among the few with enough mobility and with half-lives long enough to make their detection at long distances realistic. Existing radioxenon detection systems used by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) suffer from problems such as complexity, need for high maintenance and memory effect. To study the response of CdZnTe (CZT) detectors to xenon radioisotopes and investigate whether it is capable of mitigating the aforementioned issues with the current radioxenon detection systems, a prototype detector utilizing two coplanar CZT detectors was built and tested at Oregon State University. The detection system measures xenon radioisotopes through beta-gamma coincidence technique by detecting coincidence events between the two detectors. In this paper, we introduce the detector design and report our measurement results with radioactive lab sources and 135Xe produced in the OSU TRIGA reactor. Minimum Detectable Concentration (MDC) for 135Xe was calculated to be 1.47 ± 0.05 mBq/m3.
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- 2017
37. The development of a rapid and highly sensitive monitoring system for radioxenon isotopes
- Author
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Yanjie Tian, Jixing Du, Chengzhou Fan, Qunshu Wang, Haifei Zhang, Shujuan Feng, Junli Li, Huaicheng Ma, Bin Long, and Guoqing Zhou
- Subjects
Nuclear Weapons ,010504 meteorology & atmospheric sciences ,Isotope ,Health, Toxicology and Mutagenesis ,Nuclear engineering ,chemistry.chemical_element ,Monitoring system ,General Medicine ,010501 environmental sciences ,Technical specifications ,01 natural sciences ,Pollution ,Highly sensitive ,Xenon ,chemistry ,Air Pollutants, Radioactive ,Radiation Monitoring ,Environmental Chemistry ,Environmental science ,Waste Management and Disposal ,Radioactive gas ,Xenon Radioisotopes ,0105 earth and related environmental sciences ,Safety monitoring ,Leakage (electronics) - Abstract
The rapid monitoring of radioactive gas is one of the most direct and sensitive methods used to characterize the leakage of nuclear installations, and its technical difficulty lies in achieving the goals of rapid and high sensitivity as much as possible. Several techniques, including adsorption at ultralow temperatures, impurity removal with hollow fiber membranes, and on-site measurements with low background, were used to develop a rapid and highly sensitive monitoring system for radioxenon isotope. This system could simultaneously separate xenon from air and measure radioxenon isotopes in a rapid and efficient way. The technical specifications of this system are as follows: the recovery of stable xenon is greater than 70%; and the MDCs of 133Xe and 135Xe are 4.3 Bq/m3 and 0.4 Bq/m3 within a 30 min cycle of sampling and testing, respectively. It is worth noting that the MDC of 133Xe here is only approximately 1/18000 to 1/800 of those obtained with other similar equipment, and the monitoring period of this system is one fortieth of that of noble gas equipment for OSI, for example, XESPM-III. As a result, the standard uncertainties are less than 16%. The system developed in this paper can be applied in leakage monitoring of nuclear facilities and can also provide instructive technical support for other tests, such as nuclear safety monitoring and evaluation.
- Published
- 2019
38. Toward Understanding Cerebral Blood Flow during Cardiopulmonary Bypass: Implications for the Central Nervous System
- Author
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J G, Reves
- Subjects
Cardiopulmonary Bypass ,Hypothermia, Induced ,Cerebrovascular Circulation ,Monitoring, Intraoperative ,Humans ,Xenon Radioisotopes ,Body Temperature - Abstract
Factors and Their Influence on Regional Cerebral Blood Flow during Nonpulsatile Cardiopulmonary Bypass. By Govier AV, Reves JG, McKay RD, Karp RB, Zorn GL, Morawetz RB, Smith LR, Adams M, and Freeman AM. Ann Thorac Surg. 1984; 38:609-13. Reprinted with permission.In this study, we examined the relationship of regional cerebral blood flow (CBF) to mean arterial pressure, systemic blood flow, partial pressure of arterial carbon dioxide (PaCO2), nasopharyngeal temperature, and hemoglobin during hypothermic nonpulsatile cardiopulmonary bypass (CPB). Regional CBF was determined by clearance of xenon 133 in 67 patients undergoing coronary bypass grafting procedures. There was a significant decrease in regional CBF (55% decrease) during CPB, with nasopharyngeal temperature and PaCO2 being the only two significant factors (p0.05). In a subgroup of 10 patients, variation of pump flow between 1.0 and 2.0 L/min/m2 did not significantly affect regional CBF. We conclude that cerebral autoregulation is retained during hypothermic CPB. Under the usual conditions of CPB, variations in flow and pressure are not associated with important physiologic or detrimental clinical effects.
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- 2019
39. Measurement of radioxenon and radioargon in air from soil with elevated uranium concentration
- Author
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T. Fritioff, L. Raghoo, Johan Kastlander, M. Aldener, and Roland Purtschert
- Subjects
Nuclear explosion ,010504 meteorology & atmospheric sciences ,530 Physics ,Health, Toxicology and Mutagenesis ,chemistry.chemical_element ,Radon ,010501 environmental sciences ,01 natural sciences ,Xenon ,Radiation Monitoring ,Isotopes of xenon ,Environmental Chemistry ,Nuclide ,Argon ,Waste Management and Disposal ,0105 earth and related environmental sciences ,Radioisotopes ,Sweden ,Radionuclide ,Isotopes of argon ,General Medicine ,Uranium ,Pollution ,chemistry ,Air Pollutants, Radioactive ,Environmental chemistry ,Environmental science ,Xenon Radioisotopes - Abstract
Among the most important indicators for an underground nuclear explosion are the radioactive xenon isotopes 131mXe, 133Xe, 133mXe and 135Xe and the radioactive argon isotope 37Ar. In order to evaluate a detection of these nuclides in the context of a nuclear test verification regime it is crucial to have knowledge about expected background concentrations. Sub soil gas sampling was carried out on the oil shale ash waste pile in Kvarntorp, Sweden, a location with known elevated uranium content where 133Xe and 37Ar were detected in concentrations up to 120 mBq/m3 and 40 mBq/m3 respectively. These data provides one of the first times when xenon and argon were both detected in the same sub soil gas. This, and the correlations between the radionuclides, the sub soil gas contents (i.e. CO2, O2, and radon) and uranium concentration in the pile, provide very interesting information regarding the natural background and the xenon concentration levels and can most likely be used as an upper limit on what to be expected naturally occurring.
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- 2019
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40. International challenge to model the long-range transport of radioxenon released from medical isotope production to six Comprehensive Nuclear-Test-Ban Treaty monitoring stations
- Author
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S. Generoso, Rich Britton, Blake Orr, Alice M. Crawford, Fong Ngan, Pieter De Meutter, L. G. Glascoe, Tianfeng Chai, Olivier Saunier, A.V. Davies, Denis Quélo, Andy Delcloo, Anne Philipp, Anne Mathieu, Martin Kalinowski, T.W. Bowyer, Donald D. Lucas, Jonathan Baré, Christian Maurer, Jolanta Kusmierczyk-Michulec, Ole Ross, Matthew Simpson, Susan Leadbetter, Petra Seibert, Yuichi Kijima, Pascal Achim, Paul W. Eslinger, Phil Vogt, Michael Schoeppner, Alain Malo, Ariel F. Stein, A. Ringbom, Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut de Radioprotection et de Sûreté Nucléaire (IRSN), NOAA Air Resources Laboratory (ARL), National Oceanic and Atmospheric Administration (NOAA), Institut Royal Météorologique de Belgique [Bruxelles] - Royal Meteorological Institute (IRM), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Institut Royal Météorologique de Belgique [Bruxelles] (IRM)
- Subjects
010504 meteorology & atmospheric sciences ,Meteorology ,International Cooperation ,Health, Toxicology and Mutagenesis ,010502 geochemistry & geophysics ,01 natural sciences ,Time frame ,Radiation Monitoring ,Comprehensive Nuclear-Test-Ban Treaty ,Range (statistics) ,Environmental Chemistry ,Production (economics) ,Waste Management and Disposal ,0105 earth and related environmental sciences ,[PHYS]Physics [physics] ,Comparability ,Australia ,Monitoring system ,Ranging ,General Medicine ,Grid ,Pollution ,Air Pollutants, Radioactive ,13. Climate action ,Environmental science ,Xenon Radioisotopes - Abstract
International audience; After performing a first multi-model exercise in 2015 a comprehensive and technically more demanding atmospheric transport modelling challenge was organized in 2016. Release data were provided by the Australian Nuclear Science and Technology Organization radiopharmaceutical facility in Sydney (Australia) for a one month period. Measured samples for the same time frame were gathered from six International Monitoring System stations in the Southern Hemisphere with distances to the source ranging between 680 (Melbourne) and about 17,000 km (Tristan da Cunha). Participants were prompted to work with unit emissions in pre-defined emission intervals (daily, half-daily, 3-hourly and hourly emission segment lengths) and in order to perform a blind test actual emission values were not provided to them. Despite the quite different settings of the two atmospheric transport modelling challenges there is common evidence that for long-range atmospheric transport using temporally highly resolved emissions and highly space-resolved meteorological input fields has no significant advantage compared to using lower resolved ones. As well an uncertainty of up to 20% in the daily stack emission data turns out to be acceptable for the purpose of a study like this. Model performance at individual stations is quite diverse depending largely on successfully capturing boundary layer processes. No single model-meteorology combination performs best for all stations. Moreover, the stations statistics do not depend on the distance between the source and the individual stations. Finally, it became more evident how future exercises need to be designed. Set-up parameters like the meteorological driver or the output grid resolution should be pre-scribed in order to enhance diversity as well as comparability among model runs.
- Published
- 2018
41. Improving the estimation accuracy of multi-nuclide source term estimation method for severe nuclear accidents using temporal convolutional network optimized by Bayesian optimization and hyperband.
- Author
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Ling Y, Huang T, Yue Q, Shan Q, Hei D, Zhang X, Shi C, and Jia W
- Subjects
- Bayes Theorem, Cesium Radioisotopes, Iodine Radioisotopes, Xenon Radioisotopes, Radiation Monitoring, Radioactive Hazard Release
- Abstract
During a nuclear accident, estimating the source terms using environmental measurements is vital for emergency decision-making. In this study, we propose a forecasting model based on a temporal convolutional network to estimate the release rates of seven radionuclides (Kr-88, Te-132, I-131, Xe-133, Cs-137, Ba-140, and Ce-144) based on off-site sequential gamma dose rates and meteorological monitoring data. To determine the best structure of the neural network, Bayesian optimization and hyperband (BOHB) was used on the hyperparameters of the model to reduce the testing loss. Additionally, a gradient boosting regression model was used to predict missing gamma dose rates to ensure the model offers a relatively reliable estimate under certain circumstances. The international radiological assessment system (InterRAS) was used to generate datasets for model training and testing. The results showed that the optimal hyperparameters selected by BOHB can reduce the valid loss of the model to 0.0153, and the mean absolute percentage error of prediction for the seven radionuclides was below 12%, three of which (Kr-88, Te-132, Cs-137) reached 8% at 10 h. When the first and second time-steps of the data were missing, the mean absolute percentage error of the prediction for all radionuclides was less than 30% after using a gradient boosting regression., (Copyright © 2021 Elsevier Ltd. All rights reserved.)
- Published
- 2022
- Full Text
- View/download PDF
42. Source type estimation using noble gas samples
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Harry S. Miley, William S. Rosenthal, Brian T. Schrom, Paul W. Eslinger, and Justin D. Lowrey
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Radionuclide ,010504 meteorology & atmospheric sciences ,Isotope ,Health, Toxicology and Mutagenesis ,Bayesian probability ,Noble gas ,Bayes Theorem ,Soil science ,Monitoring system ,Source type ,General Medicine ,010501 environmental sciences ,01 natural sciences ,Pollution ,Release time ,Synthetic data ,Air Pollutants, Radioactive ,Radiation Monitoring ,Nuclear Power Plants ,Environmental Chemistry ,Environmental science ,Waste Management and Disposal ,Xenon Radioisotopes ,0105 earth and related environmental sciences - Abstract
A Bayesian source-term algorithm recently published by Eslinger et al. (2019) extended previous models by including the ability to discriminate between classes of releases such as nuclear explosions, nuclear power plants, or medical isotope production facilities when multiple isotopes are measured. Using 20 release cases from a synthetic data set previously published by Haas et al. (2017), algorithm performance was demonstrated on the transport scale (400–1000 km) associated with the radionuclide samplers in the International Monitoring System. Inclusion of multiple isotopes improves release location and release time estimates over analyses using only a single isotope. The ability to discriminate between classes of releases does not depend on the accuracy of the location or time of release estimates. For some combinations of isotopes, the ability to confidently discriminate between classes of releases requires only a few samples.
- Published
- 2020
43. A CZT-based radioxenon detection system in support of the Comprehensive Nuclear-Test-Ban Treaty
- Author
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E. M. Becker, Lily Ranjbar, and Abi T. Farsoni
- Subjects
Physics ,Health, Toxicology and Mutagenesis ,Nuclear engineering ,Detector ,Public Health, Environmental and Occupational Health ,Xenon Radioisotopes ,Scintillator ,010502 geochemistry & geophysics ,010403 inorganic & nuclear chemistry ,01 natural sciences ,Pollution ,Czt detector ,Coincidence ,0104 chemical sciences ,Analytical Chemistry ,TRIGA ,Nuclear physics ,Nuclear Energy and Engineering ,Beta gamma coincidence ,Comprehensive Nuclear-Test-Ban Treaty ,Radiology, Nuclear Medicine and imaging ,Spectroscopy ,0105 earth and related environmental sciences - Abstract
In this work, a prototype radioxenon detection system was designed, developed and tested at Oregon State University to study the response of CdZnTe (CZT) detectors to xenon radioisotopes for monitoring nuclear explosions. The detector utilizes two coplanar CZT detectors and measures xenon radioisotopes through beta–gamma coincidence detection between the two detection elements. The CZT-based detection system offers excellent energy resolution and background count rate compared with scintillator-based beta–gamma coincidence detectors currently in operation at the IMS stations. In this paper, we briefly discuss the detector design and report our recent measurement results with 131mXe, 133mXe, and 133Xe produced in the TRIGA reactor at OSU.
- Published
- 2016
44. Xenon Recovery from Molybdenum-99 Production
- Author
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Patricia Paviet, James C. Bresee, and Robert Thomas Jubin
- Subjects
Nuclear explosion ,Nuclear fuel ,Waste management ,Chemistry(all) ,Xenon Radioisotopes ,Isotopes of molybdenum ,chemistry.chemical_element ,Radioactive waste ,Noble gas ,02 engineering and technology ,General Medicine ,Uranium ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Xenon ,chemistry ,Forensic engineering ,Chemical Engineering(all) ,0210 nano-technology - Abstract
The U.S. Department of Energy Office of Nuclear Energy (DOE-NE) sponsors research and development on the recycle of used commercial nuclear fuel as an option for future nuclear fuel cycles that offers increased use of uranium and thorium resources and a possible reduction in the overall cost of nuclear waste management. The two alternatives, direct disposal of used fuel and fuel recycle, are broadly referred to as open and closed fuel cycles. One requirement of a closed fuel cycle is the safe management of radioactive off-gases, which includes 14C, radioiodine and the noble gases, including radioxenon. The longest lived relevant radioxenon isotope is 127Xe; with a half-life of just 36.35 days it is feasible to trap and hold the radioxenon to allow for decay to safe environmental levels. However, the very weak chemical bonds of noble gases, in this case xenon, make them difficult to trap, which led to an extensive DOE-NE study of noble gas adsorption on various molecular sieves as an alternative to costly cryogenics processes. Preliminary results indicate that xenon adsorption at near room temperature on molecular sieves, both synthetic and natural, may have both cost and efficiency advantages over cryogenic processes. Xenon radioisotopes with short half-lives have value in the detection of underground nuclear explosions. However radioxenon released by medical isotope production facilities produces high backgrounds that complicate its use for nuclear explosion detection. Specifically, recovery of 99Mo for medical applications from short-cooled irradiated 235U targets results in the release of some radioxenon. In March 2015, by a unanimous vote of the five permanent members of the United Nations Security Council, commercial producers of 99Mo were asked to decrease and, if possible, eliminate the emissions of radioactive xenon from their production processes. The use of materials currently being evaluated for Xe and Kr capture for use in UNF processing applications may provide a cost effective mechanism to achieve the United Nations Security Council goal.
- Published
- 2016
- Full Text
- View/download PDF
45. SPALAX new generation: New process design for a more efficient xenon production system for the CTBT noble gas network
- Author
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Christophe Moulin, Claire Gréau, G. Douysset, T. Taffary, Ludovic Deliere, Sylvain Topin, Alexandre Hovesepian, and Gilbert Le Petit
- Subjects
biology ,business.industry ,Spalax ,Health, Toxicology and Mutagenesis ,Mineralogy ,Noble gas ,chemistry.chemical_element ,Monitoring system ,Retention capacity ,Process design ,General Medicine ,biology.organism_classification ,Pollution ,Xenon ,chemistry ,Air Pollutants, Radioactive ,Radiation Monitoring ,Comprehensive Nuclear-Test-Ban Treaty ,Environmental Chemistry ,Adsorption ,Process engineering ,business ,Waste Management and Disposal ,Xenon Radioisotopes ,Production system - Abstract
The SPALAX (Système de Prélèvement Automatique en Ligne avec l'Analyse du Xénon) is one of the systems used in the International Monitoring System of the Comprehensive Nuclear Test Ban Treaty (CTBT) to detect radioactive xenon releases following a nuclear explosion. Approximately 10 years after the industrialization of the first system, the CEA has developed the SPALAX New Generation, SPALAX-NG, with the aim of increasing the global sensitivity and reducing the overall size of the system. A major breakthrough has been obtained by improving the sampling stage and the purification/concentration stage. The sampling stage evolution consists of increasing the sampling capacity and improving the gas treatment efficiency across new permeation membranes, leading to an increase in the xenon production capacity by a factor of 2-3. The purification/concentration stage evolution consists of using a new adsorbent Ag@ZSM-5 (or Ag-PZ2-25) with a much larger xenon retention capacity than activated charcoal, enabling a significant reduction in the overall size of this stage. The energy consumption of the system is similar to that of the current SPALAX system. The SPALAX-NG process is able to produce samples of almost 7 cm(3) of xenon every 12 h, making it the most productive xenon process among the IMS systems.
- Published
- 2015
46. Source term estimates of radioxenon released from the BaTek medical isotope production facility using external measured air concentrations
- Author
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Justin I. McIntyre, Ulrich Stoehlker, Ian M. Cameron, Yudi Imardjoko, Harry S. Miley, Paul W. Eslinger, Johannes Robert Dumais, Vincent T. Woods, Susilo Widodo, and Pujadi Marsoem
- Subjects
Nuclear explosion ,Radionuclide ,Isotope ,Health, Toxicology and Mutagenesis ,Explosions ,chemistry.chemical_element ,General Medicine ,Atmospheric model ,Atmospheric sciences ,Pollution ,Atmosphere ,Xenon ,Stack (abstract data type) ,chemistry ,Air Pollutants, Radioactive ,Indonesia ,Radiation Monitoring ,Isotopes of xenon ,Environmental Chemistry ,Radiopharmaceuticals ,Waste Management and Disposal ,Xenon Radioisotopes ,Nuclear chemistry - Abstract
BATAN Teknologi (BaTek) operates an isotope production facility in Serpong, Indonesia that supplies (99m)Tc for use in medical procedures. Atmospheric releases of (133)Xe in the production process at BaTek are known to influence the measurements taken at the closest stations of the radionuclide network of the International Monitoring System (IMS). The purpose of the IMS is to detect evidence of nuclear explosions, including atmospheric releases of radionuclides. The major xenon isotopes released from BaTek are also produced in a nuclear explosion, but the isotopic ratios are different. Knowledge of the magnitude of releases from the isotope production facility helps inform analysts trying to decide if a specific measurement result could have originated from a nuclear explosion. A stack monitor deployed at BaTek in 2013 measured releases to the atmosphere for several isotopes. The facility operates on a weekly cycle, and the stack data for June 15-21, 2013 show a release of 1.84 × 10(13) Bq of (133)Xe. Concentrations of (133)Xe in the air are available at the same time from a xenon sampler located 14 km from BaTek. An optimization process using atmospheric transport modeling and the sampler air concentrations produced a release estimate of 1.88 × 10(13) Bq. The same optimization process yielded a release estimate of 1.70 × 10(13) Bq for a different week in 2012. The stack release value and the two optimized estimates are all within 10% of each other. Unpublished production data and the release estimate from June 2013 yield a rough annual release estimate of 8 × 10(14) Bq of (133)Xe in 2014. These multiple lines of evidence cross-validate the stack release estimates and the release estimates based on atmospheric samplers.
- Published
- 2015
47. Improved pressurized Marinelli beaker measurements of radioactive xenon in air
- Author
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Paul Fabian, Matthew G. Watrous, Tracy P. Houghton, Troy A. Robinson, Francisco Fernández, Nick R. Mann, John W. Peterson, Mark Reavis, and Pat Hipp
- Subjects
Radiation ,Chemistry ,Analytical chemistry ,Xenon Radioisotopes ,chemistry.chemical_element ,Marinelli beaker ,Equipment Design ,010501 environmental sciences ,010403 inorganic & nuclear chemistry ,01 natural sciences ,0104 chemical sciences ,Xenon ,Air pollutants ,Air Pollutants, Radioactive ,Radiation Monitoring ,Pressure ,Humans ,Overall performance ,Aluminum ,0105 earth and related environmental sciences - Abstract
INL has shown that a Marinelli beaker geometry can be used for the measurement of radioactive xenon in air using an aluminum Marinelli. A carbon fiber Marinelli was designed and constructed to improve overall performance. This composite Marinelli can withstand sample pressures of 276bar and achieve approximately a 4x performance improvement in the minimum detectable concentrations (MDCs) and concentration uncertainties. The MDCs obtained during a 24h assay for 133Xe, 131mXe, and 135Xe are: 1.4, 13, and 0.35Bq/m3.
- Published
- 2017
48. Radioxenon washout from the dog liver.
- Author
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Peters, A. and Richards, T.
- Abstract
Washout rates of Xe-133 from the canine liver have been externally recorded following injection into the hepatic artery and portal vein. Liver perfusion has been calculated from the curves on the basis of 1) the maximal slope (k), 2) the height over area (H/A) and 3) the weighted harmonic mean (whm) of the rate constants of the exponentials analysed. When a lung signal was not superimposed on the curve, H/A and whm gave values higher following arterial than following portal injection, whereas k values were no different. When a lung signal was superimposed, portal values were increased relative to arterial values, so that portal k exceeded arterial and arterial H/A and whm were no greater than portal. In addition to recording over the liver, radioactivity in the lung has been simultaneously recorded with a second detector. Exponentials analysed from liver curves showed a correlation with corresponding exponentials analysed from lung curves. No significant differences were noted in the rate constants of exponentials between arterial and portal injections, either in liver or lung curves. It is suggested that there is no essential difference between the portal and arterial intrahepatic vascular beds, and that the observed differences between arterial and portal clearances are due to factors probably of a technical nature. [ABSTRACT FROM AUTHOR]
- Published
- 1980
- Full Text
- View/download PDF
49. The detectability of the Wigwam underwater nuclear explosion by the radionuclide stations of the International Monitoring System
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J. L. Burnett, Paul W. Eslinger, and Brian D. Milbrath
- Subjects
Nuclear explosion ,Water Pollutants, Radioactive ,010504 meteorology & atmospheric sciences ,Meteorology ,Health, Toxicology and Mutagenesis ,Explosions ,010501 environmental sciences ,Nuclear weapon ,01 natural sciences ,Polynesia ,Nuclear explosive ,Radiation Monitoring ,Environmental Chemistry ,Seawater ,Underwater ,Waste Management and Disposal ,0105 earth and related environmental sciences ,Nuclear Weapons ,Radionuclide ,Fission products ,Monitoring system ,General Medicine ,Pollution ,Environmental science ,Radiation monitoring ,Xenon Radioisotopes - Abstract
The Comprehensive Nuclear-Test-Ban Treaty (CTBT) bans all nuclear explosions, including those detonated from an underwater nuclear explosion. To improve the understanding of the radionuclide signatures of such an event, and whether it would be detectable under the verification regime of the CTBT, the 1955 Wigwam underwater nuclear explosive test has been modelled. Inventory calculations and atmospheric transport modelling has been performed to estimate the activity at the radionuclide stations (RN) of the International Monitoring System (IMS). This has utilized reported release values (0.92%) and meteorological data from the event. The research shows that there is a high probability that Wigwam would have been detectable at U.S. IMS stations at Wake Island (RN77) at 8.4 d, Upi, Guam (RN80) at 10.7 d and Sand Point, AK (RN71) at 13.7 d. At these locations, the majority of IMS relevant radionuclides were fission products, such that additional radionuclides from the seawater activation had largely decayed before reaching the stations.
- Published
- 2019
50. On the usability of event zero time determinations using radioxenon isotopic activity ratios given the real atmospheric background observations
- Author
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Martin Kalinowski, Oumar Sanogo, Kassoum Yamba, Preparatory Commission for the Comprehensive Nuclear-Test-Ban Organization (CTBTO), and IDC
- Subjects
Nuclear explosion ,010504 meteorology & atmospheric sciences ,[SDV]Life Sciences [q-bio] ,Health, Toxicology and Mutagenesis ,Nuclear engineering ,Context (language use) ,010501 environmental sciences ,01 natural sciences ,7. Clean energy ,law.invention ,Radiation Monitoring ,Reference Values ,law ,Comprehensive Nuclear-Test-Ban Treaty ,Environmental Chemistry ,Waste Management and Disposal ,0105 earth and related environmental sciences ,Event (probability theory) ,Nuclear Weapons ,Radionuclide ,Isotope ,Atmosphere ,business.industry ,Usability ,General Medicine ,Nuclear reactor ,Pollution ,Air Pollutants, Radioactive ,13. Climate action ,Environmental science ,business ,Xenon Radioisotopes ,Nevada - Abstract
This work focuses on the usability of event zero time determination using xenon isotopic activity ratios. Two data sets from Nevada underground nuclear test and Fukushima accident debris were used to calculate the age of radioxenon release by considering three kinds of radioactivity release radionuclide sources: nuclear explosion scenarios, nuclear power reactor release and medical isotopes production facilities release. Typical nuclear power reactor releases were characterized and reference values are proposed for six isotopic activity ratios, which data can be considered as reference point of nuclear reactor effluents at the time of their release obtained from real observations. The same reference values of isotopic activity ratio are given for medical isotopes production facilities releases. The purpose of this study is to evaluate the use of zero-time calculation for source characterization under the assumption that a hypothesis about the event time is made. The event time information may come from a seismo-acoustic event of interest or an inverse atmospheric transport simulation or other context information. For both data sets used in this study, the age precisions are calculated and the time precision difference is evaluated and used as a parameter for the characterization of each radionuclide event. Almost all radioxenon isotopic activity ratios are found to correctly identifying the source type of the radionuclide events studied in this work. The results from this radionuclide events characterization study may be helpful for event screening activities of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO).
- Published
- 2019
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