Core Subcriticality as a Tool of Safety Enhancement

• Published in: Nuclear science and engineering Vol. 151; no. 3; pp. 335 - 343
• Main Authors: Bokov, Pavel M., Ridikas, Danas, Slessarev, Igor, Köberl, Oliver
• Format: Journal Article
• Language: English
• Published: La Grange Park, IL Taylor & Francis 01.11.2005; American Nuclear Society
• Subjects: ACCELERATOR DRIVEN TRANSMUTATION; ACCELERATORS; ACTINIDES; Applied sciences; CRITICALITY; DELAYED NEUTRON FRACTION; DOPPLER EFFECT; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fission nuclear power plants; GENERAL STUDIES OF NUCLEAR REACTORS; HYBRID SYSTEMS; Installations for energy generation and conversion: thermal and electrical energy; NEUTRONS; OPTIMIZATION; REACTIVITY COEFFICIENTS; REACTOR CORES; SAFETY; SPALLATION; SUBCRITICAL ASSEMBLIES; THERMAL HYDRAULICS; Accelerator driven system; Fission reactor safety; Transmutation; Thermohydraulics; Spallation; Delayed neutrons; Subcriticality; Optimization; Reactor core; Nuclear reactor
• DOI: 10.13182/NSE05-A2552
• ISSN: 0029-5639

Core subcriticality can play an important role if the safety enhancement of a nuclear system is necessary, in particular, when minor actinides submitted for transmutation cause essential degradation of the reactivity feedback effects or/and significant reduction of the delayed neutron fraction. The present work shows that core subcriticality together with thermohydraulics optimization can compensate for the possible degradation of the Doppler effect and the reduction of the delayed neutron fraction. The particular dependence of the spallation neutron yield allows the creation of a supplementary negative feedback effect in case of accelerator coupled hybrid systems. A number of quantitative examples are provided in this context.