Improved modelling of the neutron spectrum for the ASP accelerator

Lilley, S.; Packer, L.W.; Pampin, R.; Gilbert, Mark R.

doi:10.1016/j.fusengdes.2013.05.089

Cited by 2 publications

(2 citation statements)

References 13 publications

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“…Direct validation of the production of a specific radionuclide, ideally produced by only one, single-step reaction pathway, requires a different experimental approach. For this reason, UKAEA, in the period 2011-2015, undertook a campaign of irradiations at a 14 MeV accelerator source, ASP, hosted by AWE, Aldermaston in the UK [31][32][33][34]. More than 300 experiments were performed, involving the irradiation of thin-foil metal samples, which were then rapidly extracted to a high-purity germanium γ-spectrometer.…”

Section: Activity Measurements Using γ-Spectroscopymentioning

confidence: 99%

Nuclear data for fusion: inventory validation successes and future needs

Gilbert

2023

J. Phys. Energy

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Nuclear data, describing neutron reaction probabilities (cross sections) and decay behaviour, are critical to the design and operation of fusion experiments and future fusion power plants. Equally vital, are the inventory codes that use the data to predict neutron-induced activation and transmutation of materials, which will define the radiological hazards that must be managed during reactor operation and decommissioning. Transmutation, including gas production, combined with the neutron-induced displacement damage, will also cause the properties of materials to degrade, for example through swelling and embrittlement, eventually limiting the lifetime of components. Thus validated and accurate nuclear data and inventory codes are essential.For data validation there are decay heat measurements performed at FNS in Japan more than 20 years ago. The experiments produced an invaluable database for benchmarking of nuclear data libraries; the latest versions of several international libraries perform well against this data during tests with the FISPACT-II inventory code, although there is still scope for improvement. A recent attempt to provide fusion-relevant validation based on \(\gamma\)-spectroscopy data from neutron-irradiated material samples tests production predictions of short-lived (several hours or less) radionuclides. The detailed analysis performed for molybdenum demonstrates how these data could eventually provide a new benchmark, and also illustrates the potential benefits of further experiments targeting the longer-lived radionuclides relevant to maintenance and decommissioning timescales.There are also some successful tests of transmutation predictions with FISPACT-II. These direct validations of inventory simulations are critical for lifetime predictions and future experiments should learn lessons from the examples described for tungsten, which demonstrate the importance of an accurate description of the neutron spectrum in experiments. More novel experimental techniques are needed to measure helium production in materials such as Fe and C, but the need to validate the nuclear data evaluations used by simulations should motivate future experimental efforts.

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Section: Activity Measurements Using γ-Spectroscopymentioning

confidence: 99%

Nuclear data for fusion: inventory validation successes and future needs

Gilbert

2023

J. Phys. Energy

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“…From 2011-2015 [59,[61][62][63][64], in an effort to improve the quality of experimental reaction cross section data for fusion-relevant materials at fusion-relevant neutron energies, UKAEA undertook a series of 14 MeV neutron irradiation experiments at the experimental facility known as 'ASP', which is hosted at AWE Aldermaston in the UK. The aim of the experimental campaigns was to gain additional cross section data-points at 14 MeV for reactions where data was deficient-this is true for many important reactions for fusion materials [65,66]-and thus to aid the evaluators working on the next generation of nuclear data libraries by providing more information with which to fit the theoretical models that generate continuous cross section curves.…”

Section: Asp Experimentsmentioning

confidence: 99%

Experimental validation of inventory simulations on molybdenum and its isotopes for fusion applications

2020

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Molybdenum is a potential material for future nuclear fusion experiments and power plants. It has good thermo-mechanical properties and can be readily fabricated, making it attractive as an alternative material to tungsten (the current leading candidate) for high neutron flux and high thermal load regions of fusion devices. Unfortunately, exposure to fusion neutrons is predicted to cause significant radioactivity in elemental Mo for decades and centuries after exposure, which would be a problem during maintenance and decommissioning operations. Simulation predictions indicate that Mo activation could be reduced by isotopic adjustment (biasing). If these predictions are proven and validated, and if isotopic adjustment is technically and economically feasible, then Mo could be used in future demonstration and commercial reactors without significantly increasing the amount of long-term, higher-level radioactive waste. Transmutation (inventory) simulations used to predict activation rely on nuclear reaction data. The quality of these data impact on the confidence and uncertainty associated with predictions. Recently, UKAEA has developed benchmarks to test and validate the FISPACT-II inventory code and the input nuclear data libraries. Verification of molybdenum inventory simulations is performed against experimental decay-heat measurements from JAEA’s fusion neutron source (FNS) facility and using new data acquired from γ-spectroscopy measurements of Mo irradiated in the ASP 14 MeV facility in the UK. Results demonstrate that FISPACT-II predictions (with TENDL-2019 nuclear data) for Mo are accurate on the short-timescales (minutes, hours of irradiation and minutes, days, weeks of cooling) of these laboratory experiments. However, these kinds of experiments are limited in their coverage of the important radionuclides for decay radiation from Mo on the years, decades and beyond timescales. Further experiments with fusion relevant conditions and timescales, potentially with alternative measurement techniques, are still needed.

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Improved modelling of the neutron spectrum for the ASP accelerator

Cited by 2 publications

References 13 publications

Nuclear data for fusion: inventory validation successes and future needs

Nuclear data for fusion: inventory validation successes and future needs

Experimental validation of inventory simulations on molybdenum and its isotopes for fusion applications

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