A Rigorous Approach to Nuclear Reactor Safety Analyses
- Paper number
IAC-19,C3,3,9,x49506
- Author
Mr. Roger X. Lenard, United States, LPS
- Year
2019
- Abstract
It is generally conceded that nuclear reactors pose effectively no radiological hazard prior to generating fission power. The only recognized safety issue is that of accidental or inadvertent criticality during ground processing or from a launch vehicle failure. The space power or nuclear propulsion reactor involved in a ground processing mishap will be subjected to all manner of abuses. These could include, for example, compaction on concrete or sand, water immersion with or without compaction, intermittent immersion and exposure; these can occur coupled with partial disassembly, including loss of safety devices. Historic experiments such as the SNAPTRANS and Transient Nuclear Test (TNT), show that large insertions of reactivity result in a limited number of fissions ~ 10^19 to 10^20 before the reactor energetically disassembles. This factor limits the fission product source term, hence the potential hazard. However, the primary issue is understanding whether or not a given accident will result in any of the aforementioned conditions. If it can be shown that there are a limited number, or potential no conditions under which the reactor can become critical with respect to ground processing or launch failures, then the launch safety case is relatively straightforward to complete. Since the potential number of launch vehicle scenarios, including altitude, velocity, orientation, and impact medium are quite substantially large, the question is how to prove a given scenario won’t result in a critical event. There are only two effective mechanisms to approach the problem, experimentation and modeling and simulation. Experimentation would be exorbitantly expensive, and may not cover all the realistic scenarios. Modeling and Simulation provides an approach to coupling the most capable solid mechanics codes with the best criticality codes to show whether or not the reactor will become critical. Little Prairie Services has been developing a suite of codes and interfaces to integrate the results of massively parallel simulations of PRESTO and MCNP to develop a M&S approach to rigorous reactor safety analyses. This paper discusses our approach and latest results.
- Abstract document
- Manuscript document
IAC-19,C3,3,9,x49506.pdf (🔒 authorized access only).
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