Irradiation Program Research Articles

R&D in advanced technology fuels (ATFs) in Spain

Accident Tolerant Fuels, also known as Advanced Technology Fuels (ATFs), have the potential to improve the safety and economic performance of commercial nuclear reactors as well as to provide additional operational flexibility for responding to variations in system energy demand.The design, fabrication and in-pile behaviour of currently operating and innovative nuclear fuels to enable a reliable and safe operation of nuclear power plants is a priority for the nuclear industry. The Spanish nuclear professionals (public and private companies, academia, and research centres) have achieved significant advances in this area. Both irradiation programs in commercial reactors, along with experimental and modelling activities, were focused into comprehending and modelling different ATF concepts to understand and predict the behaviour under normal and off-normal conditions.The International Atomic Energy Agency (IAEA) sub-program “Nuclear Power Reactor Fuel Engineering” is strongly involved in the development and validation of computer codes for ATF fuel design and the valuable Spanish contribution to this sub-program is described in this article.The future Spanish R&D in this field is expected to be focused on further improvements on ATF product development and performance knowledge.

621: Stereotactic Spine Irradiation Program at MD Anderson Cancer Center: A Comprehensive Overview

621: Stereotactic Spine Irradiation Program at MD Anderson Cancer Center: A Comprehensive Overview

The eighth SINQ Target Irradiation Program, STIP-VIII

The eighth experiment of the SINQ Target Irradiation Program (STIP-VIII) included a total of 941 specimens from 25 steels, 8 zircaloys, 6 tungsten based alloys (W-alloys) and 2 silicon carbide (SiC) composites. Specimens were prepared in 2016 and 2017. Irradiation was carried out in SINQ Target-13 in two periods: June 26 to December 21, 2018 and July 30 to December 23, 2020. The total proton charge received by Target-13 is 7.8 Ah, corresponding to 1.75×1023 protons. The irradiated specimens were unpacked in 2022 and 2023 and more than 98 % of the specimens were recovered. The specimens were irradiated at temperatures between 100 and 450 °C. The maximum doses are 10.4 dpa for steels, 14.8 dpa for zircaloys, 11.5 dpa for W-alloys, and 3.5 dpa for SiC composites. The He-to-dpa ratio is in the range of 22–42 appm/dpa for steels, 13–16 appm/dpa for zircaloys, 30–36 appm/dpa for W-alloys and 90–125 appm/dpa for SiC composites.

Выбор режима фракционирования при глиомах 4 степени злокачественности в зависимости от возраста пациентов

The aim of the work is to study the effect of two dose fractionation regimens on subsequent survival in patients with grade 4 gliomas, depending on age. In 140 patients with morphologically confirmed grade 4 glioma, fractionation with the prescribed dose of 2 and 3 Gy was alternately used using a pairwise modeling strategy. Of these, 111 patients (79.3%) died, 99 (70.7%) from glioma progression. In the group <50 years old, the median overall survival as of December 2023 was 31.11 months (95% Cl: 21.0-41.2), ≥50 years – 18.99 months (95% Cl: 16.0-21.0; p=0.014). In the group ≥50 years old with the fractionation mode of 3 Gy, the median overall survival was 21.32 months (n=47; 95% Cl: 12.1-30.6), with the mode of 2 Gy – 16.29 months (n=47; 95% Cl: 12.3-20.3; p=0.037). With glioblastoma, there are no statistical differences between the two irradiation programs – the medians are 20.0 and 16.4 months, respectively (p=0.118). In the group <50 years old with the fractionation mode of 3 Gy, the median overall survival was 32.49 months (n=23; 95% Cl: 7.1-57.9), with the mode of 2 Gy – 29.11 months (n=23; 95% Cl: 17.6-40.6; p=0.717). With glioblastoma, there are no statistical differences between the two radiotherapy programs – the median is 18.3 and 23.7 months, respectively (p=0.710). The data obtained indicate the expediency of using hypofractive radiotherapy regimens for grade 4 gliomas in patients over 50 years of age, radiation therapy should be carried out with a sufficiently high dose level, including in patients over 70 years of age with good functional condition. In young patients, approaches with increasing single doses do not lead to improved results. The fractionation regimen with a dose of 2 Gy should be considered optimal for radiation therapy.

Grain Seed Treatment by a Low-Frequency Electromagnetic Field

The paper notes the potential for enhancing seed productivity through exposure to an electromagnetic field. It touches upon both theoretical and practical considerations for developing an experimental laboratory plant for pre-sowing seed treatment using a low-frequency electromagnetic field and aiming to achieve a magnetobiological effect. (Research purpose) The study aims to investigate the influence of low-frequency electromagnetic field on the composition and properties of grain seeds. (Materials and methods) Standard emitters, characterized by a magnetic induction variability of 3-75 millitesla and a radiation frequency of 1-100 Hertz, were employed to ensure the necessary treatment parameters for a batch of seeds. (Results and discussion) The study investigates the impact of magnetization on the germination process, germination energy, and the physical and chemical properties of seeds subjected to different parameters of a low-frequency electromagnetic field (ranging from 3 to 75 millitesla in magnetic induction and a radiation frequency of 10-16 Hertz).The quality of the effect was analyzed with respect to the installation parameters and seed mass, ranging from 10 to 500 grams, across various cereal crops. Subsequently, specific modes were identified, and a functional irradiation program was devised to ensure a highly effective impact on seeds, optimizing their germination, sprouting and development. (Conclusions) The impact of a low-frequency electromagnetic field on the composition and properties of grain has been studied. An experimental laboratory plant with sources of a low-frequency electromagnetic field has been developed and irradiation modes have been justified. The pre-sowing treatment of an industrial batch, the magnetobiological effect is contingent upon several factors, including the crop type and variety, activation of a biological complex in a cell that initiates the development of a seedling, seed quality and moisture content, the presence of microorganisms on the surface, pathogenic ones included, and the characteristics of irradiation sources and energy parameters. The parameters of the low-frequency electromagnetic field were determined as follows: magnetic induction ranging from 3 to 75 millitesla, a frequency 10-16 Hertz, and seed weight varying from 10 to 500 grams. These identified parameters will be applied in the development of an industrial unit designed for the preparation of seed material and enhancement of its sowing properties.

Materials qualification through the Nuclear Science User Facilities (NSUF): a case study on irradiated PM-HIP structural alloys

This article presents neutron irradiation and post-irradiation examination (PIE) capabilities available to the nuclear materials research community through the US Department of Energy’s Nuclear Science User Facilities (NSUF). The pressing need to deploy advanced nuclear reactors to combat climate change requires qualification of new fuels and materials. Among advanced manufacturing processes, powder metallurgy with hot isostatic pressing (PM-HIP) is nearest to becoming qualified for nuclear applications. This article provides examples from a recent irradiation and PIE program on a series of structural alloys fabricated by PM-HIP to illustrate how NSUF capabilities can be used to generate qualification data. The neutron irradiation experiments are described, and a sampling of results from tensile testing, nanoindentation, transmission electron microscopy, and atom probe tomography are presented, showing the favorable performance of PM-HIP alloys compared to their cast or forged counterparts under irradiation. This article provides a perspective on leveraging NSUF for future nuclear fuels and materials testing and qualification.

A Review of Candidates for a Validation Data Set for High-Assay Low-Enrichment Uranium Fuels

Many advanced reactor concept designs rely on high-assay low-enriched uranium (HALEU) fuel, enriched up to approximately 19.75% 235U by weight. Efforts are underway by the US government to increase HALEU production in the United States to meet anticipated needs. However, very few data exist for validation of computational models that include HALEU, beyond a few fresh fuel benchmark specifications in the International Reactor Physics Experiment Evaluation Project. Nevertheless, there are other data with potential value available for developing into quality benchmarks for use in data- and software-validation efforts. This paper reviews the available evaluated HALEU fuel benchmarks and some of the potentially relevant benchmarks for fresh highly enriched uranium. It then introduces experimental data for HALEU fuel irradiated at Idaho National Laboratory, from relatively recent irradiation programs at the Advanced Test Reactor. Such data should be evaluated and, if valuable, collected into detailed benchmark specifications to meet the needs of HALEU-based reactor designers.

Comparison and calibration of dose delivered by 137Cs and x-ray irradiators in mice

Objective. The Office of Radiological Security, U.S. Department of Energy's National Nuclear Security Administration, is implementing a radiological risk reduction program which seeks to minimize or eliminate the use of high activity radiological sources, including 137Cs, by replacing them with non-radioisotopic technologies, such as x-ray irradiators. The main goal of this paper is to evaluate the equivalence of the dose delivered by gamma- and x-ray irradiators in mice using experimental measurements and Monte Carlo simulations. We also propose a novel biophantom as an in situ dose calibration method. Approach. We irradiated mouse carcasses and 3D-printed mouse biophantoms in a 137Cs irradiator (Mark I-68) and an x-ray irradiator (X-Rad320) at three voltages (160 kVp, 225 kVp and 320 kVp) and measured the delivered radiation dose. A Geant4-based Monte Carlo model was developed and validated to provide a comprehensive picture of gamma- and x-ray irradiation in mice. Main Results. Our Monte Carlo model predicts a uniform dose delivered in soft-tissue for all the explored irradiation programs and in agreement with the absolute dose measurements. Our Monte Carlo model shows an energy-dependent difference between dose in bone and in soft tissue that decreases as photon energy increases. Dose rate depends on irradiator and photon energy. We observed a deviation of the measured dose from the target value of up to −9% for the Mark I-68, and up to 35% for the X-Rad320. The dose measured in the 3D-printed phantoms are equivalent to that in the carcasses within 6% uncertainty. Significance. Our results suggest that 320 kVp irradiation is a good candidate to substitute 137Cs irradiation barring a few caveats. There is a significant difference between measured and targeted doses for x-ray irradiation that suggests a strong need for in situ calibration, which can be achieved with 3D-printed mouse biophantoms. A dose correction is necessary for bone doses, which can be provided by a Monte Carlo calculation. Finally, the biological implications of the differences in dose rates and dose per photon for the different irradiation methods should be carefully assessed for each small-animal irradiation experiment.

Development of reduced activation ferritic/martensitic steels in China

Reduced-activation ferritic-martensitic (RAFM) steel is considered as the primary candidate structural material for blankets of ITER, CFETR and DEMO. Several RAFMs have been developed in China (CN-RAFMs) such as CLAM, CLF-1, modified RAFMs and oxide dispersion strengthened RAFMs (ODS-RAFMs). The mechanical properties, irradiation behaviors, additive manufacturing and joining technologies of structural materials have been comprehensively studied. Qualifications of CN-RAFMs are on-going for ITER-TBM fabrication, with emphasis on material property databases and standardization. A new neutron irradiation program is being carried out for a series of fusion materials e.g. RAFMs and ODS-RAFMs with doses up to 40 dpa. Joining technologies (e.g. electron beam welding, tungsten inert gas welding, laser beam welding and diffusion welding, etc.) and advanced additive manufacturing are performed to overcome the big challenges of the blanket fabrication before ITER, CFETR and DEMO. The databases and standards for CLAM and CLF-1 were established respectively, and the specification and qualification of them are underway for ITER-TBM.In this paper, the latest development and strategy on fusion energy in China are briefly introduced, and the progresses of R&D activities on CN-RAFMs aiming for the engineering applications are reviewed.

Recent progress in the assessment of irradiation effects for in-vessel fusion materials: tungsten and copper alloys

The present contribution highlights results of the recent irradiation campaigns applied to screen mechanical properties of advanced tungsten and copper-based materials—main candidates for the application in the plasma-facing components (PFC) in the European DEMO, which has also been presented at 28th IAEA fusion energy conference. The main challenges in the formulated irradiation programme were linked to: (I) assessment of the ductile-to-brittle transition temperature of newly developed tungsten-based materials; (ii) investigation of an industrial pure tungsten grade under high temperature irradiation, reflecting operational conditions in the high flux divertor region; (iii) assessment of the high temperature strength of CuCrZr-based alloys and composites developed to enable the extension of the operational window for the heat sink materials. The development and choice of the advanced materials is driven naturally by the need to extend the operation temperature/fluence window thereby enlarging the design space for PFCs. The obtained results helped identifying the prospective tungsten and copper-based material grades as well as yielded a number of unexpected results pointing at severe degradation of the mechanical properties due to the irradiation. The results are discussed along with the highlights of the microstructural examination. An outlook for near future investigations involving in-depth post-irradiation examination and further irradiation campaigns is provided.

Development of Green Methods for the Determination of Elemental Impurities in Commercial Pharmaceutical Tablets

In this study, two methods based on the use of diluted acids were developed: microwave-assisted wet digestion (MAWD) and microwave-assisted ultraviolet digestion (MAWD-UV). These methods are evaluated for the digestion of oral pharmaceutical drugs and further determination of elemental impurities from classes 1 (As, Cd, Hg and Pb) and 2A (Co, Ni and V) by inductively coupled plasma optical emission spectrometry (ICP-OES). Commercial drugs for the treatment of type 2 diabetes are used. No prior comminution is performed. For MAWD, the optimized conditions were 2 mol L−1 or 3 mol L−1 HNO3, 1 mL of 50% H2O2 and a 45 min or 55 min irradiation program. For MAWD-UV, the condition using 1 mol L−1 HNO3, 1.6 mL of 50% H2O2 and a 55 min irradiation program enabled the digestion of all samples. In this way, efficient methods are proposed for the digestion of commercial pharmaceutical tablets for further determination of class 1 and 2A elemental impurities (ICH Q3D guidelines).

Molten salt modelling in SPECTRA applied to MSRE

In the Netherlands, NRG has an extensive experimental irradiation program on molten salt technology. In support of this program, also system thermal hydraulic modeling capabilities are being developed in the SPECTRA code. This paper describes the (fueled) molten salt capabilities developed and presently available in the code. These include flexible input of properties and (heat) transport correlations, delayed neutron precursor drift, fission product behavior, noble gas behavior, noble metal behavior, noble metal extraction, and chromium leaching and deposition. The paper introduces the models developed and where possible their application to the Molten Salt Reactor Experiment (MSRE) data. In general, satisfactory agreements were found between experimental data and SPECTRA results, especially taking into account all the uncertainties involved in the data retrieved from MSRE which is a large integrated system test. In the next development stages, the models will be validated using separate effect tests, where clear test definition and relatively few phenomena involved will allow to quantify the accuracy of models.

Molten salt modelling capabilities in SPECTRA and application to MSRE and Mk1-PB-FHR

In support of extensive experimental irradiation program on molten salt technology at NRG in the Netherlands, system thermal hydraulic modeling capabilities are being developed in the SPECTRA code. This paper describes the (fueled) molten salt capabilities developed and presently available in the code. These include obviously flexible input of properties and (heat) transport correlations, delayed neutron precursor drift, fission product behavior, noble gas behavior, noble metal behavior, noble metal extraction, and chromium leaching and deposition. The paper will introduce the models developed and where possible their application to the Molten Salt Reactor Experiment (MSRE) data and simulation of the Mk1-PB-FHR.

Fuel rod nonlinear vibrations to detect and characterize Pellet-Cladding Interaction

Pellet-Cladding Interaction (PCI) in a Light Water Reactor is one of the major concerns to guarantee clad integrity while attempting at increasing the flexibility of PWR nuclear reactor operations to follow power grid demand. In order to forbid operations leading to clad failure, modeling capability to simulate the mechanism has improved through the years. Code development needs detailed and precise experimental data. Those data result from dedicated irradiation programs, named “power ramp tests”, carried out in experimental devices in Material Testing Reactors (e.g. in France ISABELLE in OSIRIS in the past (Alberman et al., 1997), the ADELINE loop in the Jules Horowitz Reactor JHR in the next future (Cheymol et al., 2011)). Those irradiation devices are highly instrumented to collect the most relevant information with the highest possible accuracy. In parallel with information gained thanks to post-irradiation examination programs, research is working on innovative methodologies to detect and characterize PCI kinetics during the tests. In this frame, we investigate the technological feasibility to measure the effects of PCI, on the vibrations of a nuclear fuel rod externally submitted to the turbulent axial flow rate excitation. We designed and realized the out-of-pile IMPIGRITIA set-up to reproduce, in controlled laboratory conditions, the mechanical interaction originating in the nuclear reactor. A single PWR rod test section, reproducing the main relevant geometrical and material characteristics of ADELINE experimental system, is submitted to the hydraulic excitation representative of the real case. The local closure of the gap is obtained by means of a remotely controlled expansion system. Measurements of the transverse displacement of the sample rod are collected by Laser Doppler Vibrometry. In this paper we introduce the design of the mock-up and the associated measurement method, then we present the two experimental phases and their results: the first one in air, to show the feasibility of the measurement in air in controlled conditions; the second one under turbulent flow rate to state on the feasibility of the passive detection. At the end, conclusions and perspectives for the work are discussed.

Rapid implementation of ultraviolet germicidal irradiation and reuse processes for N95 respirators at a health system during the coronavirus disease 2019 (COVID-19) pandemic.

An N95 respirator ultraviolet germicidal irradiation and reuse program was rapidly implemented at an academic health system in the United States during the coronavirus disease 2019 pandemic. This process continues to be a safe and effective way to slow the consumption rate of N95 respirators.

Determination of microplastic content in seafood: An integrated approach combined with the determination of elemental contaminants

A method for the determination of microplastic (MP) content in seafood is proposed based on the selective digestion of seafood without the degradation of MP. A simple approach was developed using diluted acid with microwave-assisted wet digestion. The following parameters were evaluated: nitric acid concentration (0.5 to 14.4 mol L−1), digestion temperature (180 to 220 °C), irradiation program holding time (10 to 30 min), MP particle size (0.3 to 5 mm), and the seafood mass (0.5 to 2 g). To develop a reliable method for the determination of MP amount, up to 2 g of an in natura seafood sample were spiked with a known amount of MP (100 mg of mixed MP). Suitable conditions were obtained using 1 mol L−1 HNO3 at 200 °C (10 min holding time). Digests were filtered and the plastic content was gravimetrically determined. The heating program was 20 min, which represents a significant reduction in the time normally reported in the literature for MP analysis (from few hours up to 3 days). The proposed method allowed gravimetric determination of eight plastic types (polyethylene terephthalate, polystyrene, expanded polystyrene, polypropylene, high and low density polyethylene, polycarbonate and polyvinyl chloride) with particle size ≥0.3 mm. Up to 2 g of an in natura seafood sample (shark species, acoupa weakfish, tuna fish, trahira, and pink shrimp) were efficiently digested, which opened the possibility of using the proposed digestion method for determining elemental contaminants (Al, As, Ca, Cd, Co, Cr, Cu, Fe, Hg, La, Mg, Mn, Mo, Ni, Pb, and Zn). Thus, as the main feature of the proposed digestion method is the possibility of determining MP and elemental contaminants using the same digestion protocol, saves time and reagents and provides accurate and precise information about different classes of marine pollutants (MP and elemental contaminants).

High-Intensity Focused Ultrasound: Heating and Destruction of Biological Tissue

The results of a numerical study of heating and destruction of a biological tissue under the action of a series of focused ultrasound pulses generated by a multielement array (tumor treatment programs) are presented. Irradiation programs are considered that differ in the locations of focal points within a tissue (the Archimedean and “square” spirals), the number of pulses in the series, and the time delay between pulses. A significant influence of the parameters of the pulse series and perfusion process on the size of the thermal lesion area in a tissue was established in a considered range of moderate intensities of radiation. It was shown that the heat propagation process in the tissue turns with time to a quasi-spherical pattern and is weakly dependent on the irradiation program type. This characteristic of the process is discussed in terms of its possible use to optimize protocols of medical procedures utilizing focused ultrasound.

Radiation response studies of acetonitrile solutions of crystal violet and leuco crystal violet

Development of radiochromic dosimetry systems for industrial and food irradiation programme is of paramount importance. Reliable dose measurements can only be achieved by understanding the radiation response and subsequent optimization of dosimeter recipe. In view of this, radiolysis of acetonitrile solutions of crystal violet and leuco crystal violet containing 2,2,2-trichloroethanol as sensitizer was studied under aerated conditions to determine role of each ingredient. In crystal violet based system, decrease in absorbance on exposure to gamma rays was linear in the dose range of 50–600 Gy. The radiochemical yield was observed to increase non-linearly with dye concentration, reaching a constant value for crystal violet concentrations greater than 50 μM. For leuco crystal violet based system, formation of coloured crystal violet cation exhibited a sigmoidal increase with dose for exposures in the range from 100 to 500 Gy. The radiochemical yields evaluated were in range of 0.0141–0.0395 μmol/J depending on the concentrations of the leuco dye and sensitizer. The observed radio-chemical behaviours of all the constituents provided interesting leads to design potential dosimetry systems.

Characterization of the radiation tolerance of cryogenic diodes for the High Luminosity LHC inner triplet circuit

Cryogenic bypass diodes are part of the baseline powering layout for the circuits of the new ${\mathrm{Nb}}_{3}\mathrm{Sn}$ based final focus magnets of the high luminosity Large Hadron Collider. They will protect the magnets against excessive transient voltages during a nonuniform quenching process. The diodes are located inside an extension to the magnet cryostat, operated in superfluid helium and exposed to ionizing radiation. Therefore, the radiation tolerance of different types of diodes has been tested at cryogenic temperatures in CERN's CHARM irradiation test facility during its 2018 run. The forward bias characteristics, the turn-on voltage and the reverse blocking voltage of each diode were measured weekly at 4.2 K and 77 K, as a function of the accumulated radiation dose. The diodes were submitted to a total dose close to 12 kGy and a 1 MeV neutron equivalent fluence of $2.2\ifmmode\times\else\texttimes\fi{}{10}^{14}\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}2}$. After the end of the irradiation program the annealing behavior of the diodes was tested by increasing the temperature slowly to 293 K. This paper describes the experimental setup, the measurement procedure and the analysis of the measurements performed during the irradiation program as well as the results of the annealing study.

Design, construction and operation of a graphite irradiation creep facility

Representative irradiated graphite properties are essential for the successful design, licensing and long term operation of a graphite moderated reactor. These properties are acquired from irradiation programs that are executed in different Materials Test Reactors around the world. Recently, the Nuclear Research and consultancy Group (NRG) has completed a graphite irradiation creep program by the name ACCENT to support long term operation of Advanced Gas-cooled Reactors in the UK.In a series of 4 irradiation steps, paired graphite specimens are irradiated at a temperature of 440 °C under loaded and non-loaded conditions. By using a modular design with pressurized bellows, a load of 5 or 10 MPa is applied to the specimens. Characterization of the graphite specimens is performed before, between and after the irradiation steps to generate graphite property curves in a range of 0 to 14 DPA.This paper describes the different design, construction and operational aspects of graphite irradiation (creep) facilities that are fundamental to successfully acquire representative irradiation data. It will be demonstrated how these different aspects are controlled for the ACCENT graphite irradiation creep facility.