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Abstract: Skin contamination by α-emitting actinides such as plutonium and americium is a risk for workers during nuclear fuel production and reactor decommissioning. Decontamination of skin is an important medical countermeasure to limit potential internal contamination, particularly in the case of injured skin. Current recommendations include undressing of the victim followed by skin washing using soap or chelating agents, such as diethylene triamine pentaacetic acid (DTPA). The goal of the present work is to assess the efficacy of a novel Ca-DTPA loaded gel to decontaminate injured skin exposed to plutonium or americium as compared to recommended treatments. For decontaminant testing on injured skin, whole body skin was obtained from euthanized rats and lesions created using a metallic brush. Delimited test areas were contaminated with plutonium or americium solutions of known properties. Various protocols were tested including time before contamination, duration of gel application, washing steps, as well as the concomitant addition or not of dressings. Activity was measured in each decontamination product and in skin. Data indicate that healthy skin was easier to decontaminate than damaged skin. On injured skin, we demonstrated an increased decontamination efficacy of the Ca-DTPA gel formulation as compared to the solution. Importantly, gel application alone was effective, and further gel applications could be used for residual activity., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the Health Physics Society.)

Abstract: The Human Monitoring Laboratory, Health Canada (HML), has used a 3D printer to re-engineer its Lawrence Livermore National Laboratory (LLNL) foam lung sets (manufactured by Radiology Support Devices, Inc., Long Beach, CA). The foam sets are currently the HML standard for calibrating and performance testing lung-counting systems in Canada. This paper describes the process of creating and validating new 3D-printed lung sets modeled from one of the HML's existing RSD foam sets. The existing sets were custom made, making them costly and difficult to obtain or replace. Also, after many years of use, the HML has found that they are prone to wear and tear. When used with planar inserts containing various isotopes, the blank sets can become contaminated and are difficult to clean. Using 3D printing, the HML has created new blank lung sets that are nearly identical copies of the originals and are inexpensive and easily manufactured. Measurements using natural uranium (Nat U), 241Am, and 152Eu planar lung inserts were performed to compare obtained efficiencies at a wide range of energies using the original RSD foam sets and the 3D-printed ones. Both the foam and the 3D-printed lung sets were counted using the LLNL chest phantom positioned in the same counting geometry in the lung counting system. Biases, all below 15%, were obtained between the foam and the 3D-printed sets for energies above 40 KeV. Based on these results, as well as cost benefits and ease of use, the HML has decided to replace its original RSD foam lung set with the 3D-printed version for its lung performance testing program., (Copyright © 2024 Health Physics Society.)

The article discusses the analysis of error related to the direct in-vivo measurements of radionuclides present in a wound. The authors illustrate the error analysis by considering the radiation injury to a hand using the Americium radionuclide. According to them, the results of error analysis show that remarkable errors may propagate if the lowest energy peaks of Americium are used during the measurements of the wound.

The article attempts to derive the sensitivity requirements for the urine bioassay techniques for the top 10 high-risk radionucleotides that might be used in terrorism. It lists some of the published methods or techniques for radionucleotide urine bioassay and some of their performance characteristics. A review of available assay techniques is summarized and revealed that method development for americium, radium, plutonium and strontium urine bioassay is needed to monitor radiation emergency.

The article discusses a study that proposes a single model for the decorporation of americium and plutonium through diethylene triamine pentaacetic acid (DTPA) therapy. The efficacy of the decorporation is influenced by DTPA ratio to the actinides. A higher decorporation of americium may be obtained by the affinity of the ligands to the actinide. The variation in the decorporation is influenced by the actinide, radionuclide, the dose of the DTPA and schedule of treatments.

The article reports on the inhalation of 241Am oxide by three workers while sorting and compacting waste materials. The activity of 241Am in the liver, skeleton and lungs are quantified by in vivo bioassay measurements for a period of six months. The clinical laboratory and medical tests performed on the subjects are all normal. The workers are given different therapies and their effectiveness are measured by the ratio of the reference to the assessed dose.

The article reports on the 12-year monitoring of workers contaminated with 241Am because of the americium oxide powder that they use to produce the neutron sources of AmBe. The National Radiation Protection Institute in Prague, Czech Republic improved its in vivo measurement for its follow-up of the contaminated workers since early 1970. The results found that the excretion rate is lower than the prediction model.

The article discusses a study on novel solid sorbents that may be used as decorporating agents for actinides such as plutonium, americium, uranium and thorium from complex biological matrices like blood and plasma. Self-assembled monolayer on mesoporous supports (SAMMS) were evaluated for actinide chelation and scientists noted the high affinity for actinides. Potential uses include sensing, diagnostics, and wound decontamination as well as resolution of exposures to radionuclides other than actinides.

The article discusses the efficacy of orally-administered polyaminocarboxylic acid (PACA) chelators on americium and plutonium decorporation and provides data on the absorption and excretion of oral chelators. It also talks about synthesis and purification methods as well as the prevention of plutonium redeposition onto bone surfaces. Initial findings show efficacy of the oral chelators, reasonable bioavailability, and substantial biliary/fecal excretion route which may facilitate depletion of radionuclides in the liver.

The article discusses a study on the specific biological behavior of plutonium and americium after inhalation of PuO2 with two different isotopic and elemental compositions. Results show that americium content affected dissolution of actinides and subsequent distribution to the lungs and urinary excretion. Americium is said to be more transportable and promotes extra-pulmonary retention of radiological doses more than plutonium does.

The article describes the modification of the Livermore Torso Phantom at the University of Cincinnati, Ohio to accommodate a surrogate for the axillary lymph nodes. It relates that a worker had unknowingly sustained a wound contaminated with Americium. It discusses the identification of the fixed locations for the axillary lymph nodes in the phantom, as well as the discrete calibration measurements for Americium in the lymph nodes located in the thorax.

The article focuses on a study which examined the application of neutron dose perfluence and weighting factors to the energy spectra of 241Americium-Beryllium (Am-Be) sources and a set of neuron radiation fields found at a high energy proton accelerator. The neutron dose perfluence and weighting factors mentioned correspond to the U.S. Department of Energy's occupational radiation protection regulation Title 10, Code of Federal Regulations Part 835 which forms part of updating its radiation dosimetry system. It provides a description of a number of radiological quantities introduced by documents describing the new system. It details the application of radiation weighting and quality factors to alpha-neutron sealed sources such as Am-Be neutron spectra.

This article discusses the Bayesian method for hypothesis testing as applied to internal plutonium and americium dosimetry cases at Los Alamos National Laboratory, New Mexico. The authors compare the Bayesian method where the interpretation of the measurements builds on and depends upon the prior probability distribution with classical statistical approaches. They argue that all the data should always be taken into account. They conclude that if there are many cases available, then the difference between Bayesian and classical statistics is slight, but when data are limited, the distinction becomes important.

This article discusses the use of imaging plates without shielding to monitor Americium exposure in the human lung. According to the authors, high energy alpha wave radiation exposure from plutonium sources has previously required bioassay or external counting methods. They argue that the lower detection limit of the imaging plate system developed by the U.S. Lawrence Livermore National Laboratory is the same as the germanium detector and the phoswich detectors. These imaging plates were sealed in lightproof bags and tested on the realistic torso phantom. They have also been used successfully with radioiodine isotopes in the thyroid.

The article presents information regarding the experiment on the systemic distribution of americium in the beagle dogs. The experiment model was developed measuring the excreted radio activity and organ burdens for different levels of initial injected activity. The adopted parameters in developing the plutonium model was the compartmental structure of the skeleton. In the experiment, only the numerical values of parameters were adapted and the model described the fractions of americium in the skeleton, liver and soft tissues and the total fraction excreted in urine and feces. A realistic description of the change in the partitioning between liver and skeleton for different injection levels was provided by different parameters. The important features of the biokinetics and dosimetry of americium and plutonium in beagles are compared and found that in case of plutonium the total fractions of the clearance to the skeleton and the liver are roughly equal to the value of it. But in case of americium the partitioning between these organs is reversed with respect to the partitioning of plutonium.

Airborne effluents of 5 stacks (stacks 1-5) of three nuclear power plants, with 9 pressurized water reactors VVER of 4,520 MWe total power, were searched for transuranium isotopes in different time periods. The search started in 1985. The subject of this work is a presentation of discharge data for the period of 1998-2003 and a final evaluation. It was found that 238Pu, 239,240Pu, 241Am, 242Cm, and 244Cm can be present in airborne effluents. Transuranium isotope contents in most of the quarterly effluent samples from stacks 2, 4 and 5 were not measurable. Transuranium isotopes were present in the effluents from stack I during all 9 years of the study and from stack 3 since the 3rd quarter of 1996 as a result of a defect in the fuel cladding. A relatively high increase of transuranium isotopes in effluents from stack 3 occurred in the 3rd quarter of 1999, and a smaller increase occurred in the 3rd quarter of 2003. In each instance 242Cm prevailed in the transuranium isotope mixtures. 238Pu/239,240Pu, 241Am/239,240Pu, 242Cm/239,240Pu, and 244Cm/239,240Pu ratios in fuel for different burn-up were calculated, and comparison of these ratios in fuel and effluents was performed. [ABSTRACT FROM AUTHOR]

Abstract: The paper is concerned with the issue of achieving the radiological equivalence (the equivalence of radiation risks) of radioactive waste of nuclear reactors and corresponding mass of natural uranium, taking into account the different migration ability of radionuclides in geological formations and soil. This migration radiological equivalence is being investigated for the deep burial of radioactive waste in the case of the development of a two-component nuclear power system with the concurrent use of thermal neutron reactors and fast neutron reactors. Calculations were performed of radiation doses and radiation risks of cancer death arising from consumption of drinking water from a well above a disposal site. The radiation risk relating to a two-component nuclear power system is lower than that from natural uranium; i.e., after reaching the radiological equivalence (100 y of storage) over the timescale of 109 y, the principle of migration radiological equivalence is satisfied. It would take 106 y after radioactive waste disposal to reach the migration radiological equivalence if only thermal reactors were operated. As regards consumption of well drinking water, the radiation risk does not exceed 10-5 y-1 for a two-component nuclear power system, while being 10-3 y-1 (socially unacceptable level) for a power system using only thermal reactors. Radionuclides 241Am, 239Pu, and 240Pu in drinking water make the main contribution to the doses and radiation risks of people for 104 y after the disposal of radioactive waste., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2021 Health Physics Society.)

Abstract: This whole-body tissue donor to the United States Transuranium and Uranium Registries was occupationally exposed to plutonium nitrate-dioxide mixture via chronic inhalation. This individual was involved in the Manhattan Project operations and later participated in medical follow-up studies. Soft tissues and bones collected at autopsy were analyzed for 238Pu, 239+240Pu, and 241Am. Fifty-three years post-intake, 700±2 Bq of 239+240Pu were still retained in the skeleton, 661±11 Bq in the liver, and 282±3 Bq in the respiratory tract. Bioassay measurements and organ activities at the time of death were used to estimate the intake and radiation doses using the TAURUS internal dosimetry software. For this individual, an ICRP Publication 130 Human Respiratory Tract Model with case-specific particle size of 0.3 μm, ICRP Publication 100 Human Alimentary Tract Model, and ICRP Publication 141 Plutonium Systemic Model adequately described long-term plutonium retention and excretion. The total cumulative 239+240Pu intake of 31,716 Bq was estimated, of which 24,853 Bq (78.4%) were contributed by inhalation of plutonium nitrate and 6,863 Bq (21.6%) of plutonium dioxide. The committed equivalent doses to the red bone marrow, bone surface, liver, lungs, and brain were 0.71 Sv, 6.5 Sv, 8.3 Sv, 3.8 Sv, and 0.068 Sv, respectively. The committed effective dose was 1.22 Sv., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2021 Health Physics Society.)

The article presents questions and answers related to smoke detectors and light bulbs. One person asks if light bulbs stored in warehouse pose any risk to employees handling them. Another queries about the americium oxide contained within smoke detectors. A reader asks if removal or tampering with the americium-241 source prohibited by law from smoke detectors.

Incident reports describing stolen source events in Texas from the years 1956 to 2000 were obtained from the Texas Department of Health-Bureau of Radiation Control and recorded into a computerized database using a pre-established set of codes. The data were then analyzed for the identification and characterization of trends. Over the 45-y period of analysis, 113 sources were reported as stolen. The radionuclides most commonly reported in theft events were Am, Cs, and Ir. The proportion of sources including Am as the sole source or Am combined with Be, or as a companion source with Cs, represented 56% of the total reported as stolen. Key risk factors identified as associated with source theft appear to include portability status, transportation status, transporter status, and radionuclide type. Based on the observations noted, suggested improved security measures are postulated including additional permitting controls, enhanced inspections, improved locking and storage procedures, and steps for communication to the public to enhance the prospects for recovery. Suggested enhancements to further improve data collection are proposed so that crime prevention information can be derived in future research.