ADVERTORIAL FEATURE | AMENTUM
Testing times in the material world
Amentum’s experts take a break from the laboratory to provide an insight into crucial research which could make or break the nuclear resurgence
NUCLEAR REACTORS BEING DESIGNED today have a host of new features and benefits, but they will only perform safely and efficiently if designers and operators learn from decades of research into the degradation mechanisms that affect the materials they are made of. The same applies to fusion power, where the use of
materials such as lithium has created the need for new research to plug gaps in our knowledge. Dr Mayur Jagatia, Amentum’s Group Director of Materials
Science and Structural Integrity, says: “To ensure that the nuclear resurgence fulfils its potential, we need to use the experience of past and present reactor technologies to enable the future. “Amentum’s experts are undertaking materials and chemistry testing for numerous designers and developers of new reactor types. There has never been a greater demand for our deep understanding of reactor science, our advanced modelling capability, and our vast amount of accumulated data on materials performance and accelerated ageing. “Our work on the UK’s advanced gas-cooled reactor fleet
Below: Work in progress at Amentum’s chemistry laboratory in Warrington
is closely aligned with the challenges faced by developers of high-temperature advanced modular reactors (AMR), namely the need for a deep understanding of graphite material behaviour and the impact on reactor safety of failure mechanisms such as creep. “We are applying our research and development philosophy to enable designers to better understand these challenges, for example by developing new rigs that more closely represent the pressure and temperature of operational envelopes in the new generation of reactors.” Amentum’s experts picked out five areas where materials
science and chemistry research is critical to the new technologies underpinning the nuclear resurgence:
Finite element analysis and structural assessment of graphite reactor cores Amentum has played a central role in supporting the UK’s advanced gas-cooled reactors (AGRs) for more than 40 years, underpinning safe operation and life extension across the fleet. The graphite reactor core undergoes changes throughout its lifetime, due to fast neutron irradiation and radiolytic oxidation. To assess the impact on core integrity and functionality, Amentum has developed bespoke finite-element models complete with graphite-specific material subroutines. These methods span multiple scales, from single component assessments and small arrays to whole-core simulations. Amentum has also developed mathematical models that interface with the whole-core models to quantify the function of each channel and thus the ability of the core to safely shut-down. These well-validated models are central to the safety cases of the UK’s AGR fleet. With many next-generation reactor designs featuring
graphite cores, Amentum’s modelling expertise is more relevant than ever. In addition to producing electricity, these advanced designs enable industrial decarbonisation through high-grade process heat, including for hydrogen production. Our team is actively adapting our modelling frameworks to accommodate new graphite grades, core and component geometries, and operational conditions. This capability positions Amentum at the forefront of the nuclear resurgence, helping to accelerate the development and licensing of the reactors of tomorrow.
Combined computational modelling and physical testing Combining computational models and physical testing enables the prediction of future reactor core states, to ensure safe operation. Physical tests can both enable the validation of computational models and provide key inputs to them. For the graphite cores in the UK’s AGR fleet, computational finite element analysis models are used to determine internal and external stresses of irradiated graphite components. It is important to understand the stress state at which
cracking will initiate and this is determined by the use of full-scale component testing. Unlike metal, graphite is a brittle and heterogeneous material, so traditional tensile tests on coupons may not be representative of populations of components. In recent work, our teams developed a programme of targeted destructive testing on replica AGR fuel brick slices, paired with high fidelity-finite element analysis, to determine the critical stresses at which graphite components fail. These critical stresses are then used by other teams in Amentum to help understand the structural integrity of graphite components in reactor conditions, ultimately justifying the safe operation of the AGRs.
34 | WNE Special Edition |
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