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Several intense energy irradiation testing facilities are functional to study the effects of radiation damage in fusion materials. Tungsten is a potential candidate material to build the plasma-facing armour components of fusion reactors. Therefore, it is vital to estimate the radiation-induced primary damage in the material, particularly due to the large amount of transmutation nuclides produced in the high-energy neutron sources. The basic evaluated nuclear data libraries provide the essential neutron reaction data to estimate the transmutations and their effects during irradiation. However, much of the important high-energy neutron reaction data are often not explicitly provided to directly study their impact on radiation damage. Such inexplicit nuclear reaction data, especially for the transmutation nuclides, can have a significant effect on the estimation of primary radiation damage. A new specific methodology has been developed to unravel information from these inexplicit nuclear reaction data from the basic ENDF-6 libraries and use them with explicit data for estimating the primary radiation damage. The energy distributions of transmuted nuclides (the recoil nuclei in general) and light charged particles produced as a result of several types of neutron–nucleus interactions in tungsten, are quantified using the cross-sections from ENDF / B-VIII.0 and TENDL-2019 basic evaluated nuclear data libraries and their inter-comparisons are carried out. The neutron-induced atomic displacements and heating in tungsten are estimated for irradiations under the fusion and IFMIF-DLi neutron spectra. It shows that the transmutation reactions under these neutron spectra can sometimes contribute more than 50% of the total primary damage, most of which can be from inexplicit nuclear reaction data. Significant differences between the two sources of basic evaluated nuclear data libraries, especially in the production of transmutation nuclides and consequently, in their contributions to damage are observed. The present study helps to illustrate the importance of inexplicit nuclear reaction data and the usefulness of the ENDF-6 libraries for estimating primary radiation damage due to transmutations in plasma-facing materials. [ABSTRACT FROM AUTHOR]

Hadron therapy (HT) is a technique that uses accelerated ions, notably protons, and carbon ions, to destroy tumors. It has demonstrated high success rates in the treatment of certain cancers resistant to irradiation. In HT, the majority of the dose is delivered to the tumor volume by electromagnetic interactions with atomic electrons. However, it is important to note that the primary particles used in HT can induce nuclear reactions, generating undesirable secondary radiation, certainly neutrons. As a result, a significant portion of the patients' body may be exposed to the secondary background radiation field. Thus, these unwanted secondary neutrons should be evaluated. The purpose of this research in first is to characterize the secondary neutron production (SNP) during the administration of Hadrons with energies 140 MeV proton, and 264 MeV/u carbon ions ( C) in a soft tissue phantom. Second, comparing the neutron spectrum for different angles for protons and carbon ions for carbon targets to experimental data. Our results show that the neutron spectra (thick target neutron yields TTNYs) at energies less than 20 MeV, using the INCL4.6/GEM models and JQMD/GEM across a wide range would be suitable for the Monte Carlo transport simulation. [ABSTRACT FROM AUTHOR]

In the present work, the neutron yield of a Pu-Be neutron source has been calculated by using two methods, calculation with the SOURCES4C code developed at LANL and via an equation, respectively. The present work aims to determine and compare the two methods in obtaining the yields and spectra of an (a,n) type neutron source. The source used for this work is being held at IFIN-HH, and was well experimentally characterized in previous work. The results of the present work compare well with the experimental data. [ABSTRACT FROM AUTHOR]

Featured Application: Numerical modelling of yields and distributions of nuclear fusion products in magnetically confined plasma. Velocity distributions of fuel nuclei enter the formulae for distributions of products of fusion reactions in plasma. The formulae contain multiple integration, which is a computationally heavy task. Therefore, simplifications of the integrand are advantageous. One of possible simplifications is the use of closed-form analytical distributions of fast deuterons and tritons, accounting for slowing down and pitch-angle scattering and neglecting the speed diffusion. The plausibility of such a model has been studied from the viewpoint of its influence on the calculated spectra of fusion neutrons. Calculations have shown that the speed diffusion effect on suprathermal ion distribution tails does not significantly alter the qualitative behaviour of energy and angle distributions of fusion products in a beam-heated plasma. [ABSTRACT FROM AUTHOR]

The neutron spectrum was measured at two locations in the spent fuel storage facility of the Temelín nuclear power plant. The measurement had two primary objectives: to map the neutron -γ field by quantifying the ambient dose equivalent H∗(10) and to identify methods that could improve the quality of the adjusted neutron spectrum using a Bonner Sphere Spectrometer (BSS). Three spectrometers were used: a BSS and two proton recoil spectrometers. Hydrogen-filled proportional counters and an EJ309 scintillator were used to construct the a priori spectrum for BSS adjustment. The details of this process and its results are discussed. The a posteriori spectrum was used to calculate the ambient dose equivalent H∗(10). The resulting spectrum is highly thermalised, but the predominant contribution to H∗(10) was in the 100 keV-1.3 MeV range. The use of hydrogen-proportional counters in combination with the BSS is recommended. • Neutron spectra at spent fuel storage were measured by three spectrometers. • Ambient dose equivalent was calculated from the neutron spectra. • The neutron spectrum is highly thermalised, but most of the ambient dose equivalent is from the 100 keV-1.3 MeV energy range. • Due to the prevalence of contribution H∗(10) in range 100 keV-1.3 MeV use of hydrogen proportional counter spectrometer is recommended. [ABSTRACT FROM AUTHOR]

The nuclear physical properties of austenitic chromium-nickel steel EK-164 (Fe–16Cr–19Ni–2Mo–2Mn–Nb–Ti–B) and its manganese-based modifications EK-164Mn (Fe–16Cr–20Mn–2Mo–Nb–Ti–B) and EK-164MnW (Fe–16Cr–20Mn–2W–Nb–Ti–B) under irradiation (up to 5 effective years) in the neutron spectra of fast power (BN-600) and thermonuclear (DEMO-C) reactors and after irradiation (nuclear cooling up to 1000 years) were determined. The investigations were based on using the ACDAM-2.0 calculation complex with consideration of the elemental (alloying and impurity) compositions of steels and typical neutron spectra of fission (BN-600) and fusion (DEMO-C) reactors. The entire set of nuclear physical characteristics of steels (primary radiation damage; transmutation of elements; radiogenic accumulation of elements, including hydrogen, helium, and boron; γ-dose rate; radioactivity; nuclear energy release; isotope contributions) is obtained and their comparative analysis is performed. The time intervals for fulfilling the criteria of low activation of steels after irradiation (γ-dose rate less than 10 mSv/h, radioactivity less than 1010 Bq/kg, energy release less than 10 W/m3) were determined. [ABSTRACT FROM AUTHOR]

Velocity distributions of fuel nuclei enter the formulae for distributions of products of fusion reactions in plasma. The formulae contain multiple integration, which is a computationally heavy task. Therefore, simplifications of the integrand are advantageous. One of possible simplifications is the use of closed-form analytical distributions of fast deuterons and tritons, accounting for slowing down and pitch-angle scattering and neglecting the speed diffusion. The plausibility of such a model has been studied from the viewpoint of its influence on the calculated spectra of fusion neutrons. Calculations have shown that the speed diffusion effect on suprathermal ion distribution tails does not significantly alter the qualitative behaviour of energy and angle distributions of fusion products in a beam-heated plasma.

Two organic scintillators (EJ309 and stilbene) with their different detection chains and elaborate software were used to measure neutron spectra of AmBe and PuC sources. Method of shadow cone ensures minimization of scattered neutron influence. To separate neutrons and γ, a modern method of pulse shape discrimination was employed using fast digitizers. Calibration was performed by γ sources and three different methods for the identification of the Compton edge. Spectrometric systems also used different light output functions and unfolding methods. The same spectra were calculated using the MCNP6 code and the JENDL-5 library. The measured and calculated results were mutually compared, and also with the published results available in the literature. Generally, the results agree on the main peaks of neutron spectra but differ in their abundance. The lower limit for the ability to distinguish between neutrons and γ in spectrometry with organic scintillators was found at about 1.5 MeV. • Neutron spectra of AmBe and PuC sources were measured and calculated. • The measured/unfolded spectra and calculated ones agree in shape. • Methods of energy calibration and neutron/gamma separation are described. [ABSTRACT FROM AUTHOR]

FANT (Fuente Ampliada de Neutrones Térmicos ; in Spanish) is a thermal neutron irradiation facility with an extended and very uniform irradiation area, which has been developed by the Neutron Measurement Laboratory of the Energy Engineering Department at Universidad Politécnica de Madrid (LMN-UPM). In FANT, an isotopic neutron source (241Am/9Be) produces the primary neutrons. The design and facility optimization were carried out by extensive Monte Carlo calculations. In addition, Monte Carlo methods were used to evaluate the facility's performance to produce a constant and uniform thermal neutron field; these results were validated through experimental methods. FANT is designed to have two neutron sources; the objective of this work is to estimate the ambient dose equivalent due to neutrons and gamma-rays by Monte Carlo methods, and to compare these values with measured experimental doses. Thus, the performance of FANT with the two 241Am/9Be sources of LMN-UPM, with regard to the ambient dose equivalent H*(10) produced by both neutrons and photons around the facility, is analyzed in this work. The results are compared with those previously obtained in the framework of the results obtained with the LB6411 device around FANT. • MCNP benchmarking with experimental H*(10) measurements: γ-rays and neutrons. • H*(10) around thermal neutron irradiation facilities: total, γ-rays and neutrons. • Berthold LB6411 and LB1236 area monitors. • Radiological protection assurance around thermal neutron irradiation facilities. [ABSTRACT FROM AUTHOR]

A methodology for designing a Bonner sphere spectrometer was proposed based on the singular value decomposition (SVD) and information entropy theory. First, features of Bonner spheres were classified based on SVD, and then, the rationality of the selected spheres was analyzed. Second, the information entropy is used as the quantitative evaluation standard; combined with the unfolding method, the contribution of each Bonner sphere on the information entropy of the unfolded spectra was quantitatively analyzed. The spheres that have high influence on the information entropy of solution spectra can be identified, and then, the information entropy variation of the solution spectra can be suppressed by reducing the count fluctuation of these spheres. According to the proposed method, an optimized spectrometer was developed and applied to measuring 252Cf spectra. [ABSTRACT FROM AUTHOR]