Validation & Verification for Critical Heat Flux and CFD

The behaviour of nuclear reactors must be thoroughly analysed under a range of normal operation and (especially) fault conditions. Computer programmes that simulate the flow of fluids, (such as 'Computational Fluid Dynamics codes, or CFD codes') can in principle help with this. However, the complexities of the phenomena to be analysed are such that these codes need to be thoroughly validated against good measurements made in suitable experimental rigs. Under this proposal a team of UK researchers will collaborate with colleagues at BARC in India, where there are excellent such experimental facilities available. Experiments will be designed and analysed jointly, and used to validate such codes.

Research outputs of the kind planned are important in view of the central role that nuclear power is expected to play over the next decades. New reactors and reactor types must meet ever higher economic and safety criteria, and assessing their ability to meet these relies more and more on advanced computational modeling. Such modelling can only be relied upon if it is supported by sound experimental validation and verification. Direct beneficiaries of this will be designers, assessors and operators of nuclear plant; better analysis tools, properly validated, are essential to realize the continuing benefits of nuclear new build. Society in general will gain too, as it benefits from the economical and carbon-free energy such nuclear plant provide. Adoption within the nuclear industry of new approaches is quite properly cautious, and the impact of the work proposed here will have a range of timescales of application. Better validated CFD models could be employed essentially immediately in (say) licensing assessment, whereas fundamental improvements in understanding of, and ability to predict, CHF phenomena will quite properly take longer to work through