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Developing a new regulatory framework for advanced reactors: Update on Part 53
White
The American Nuclear Society’s Risk-informed, Performance-based Principles and Policy Committee (RP3C) on March 29 held another presentation in its monthly Community of Practice (CoP) series. The presenter, Patrick White with the Nuclear Innovation Alliance (NIA), talked about the current status of efforts to develop a new regulatory framework for advanced reactors—known as 10 CFR Part 53 or simply Part 53. White serves as the research director of the NIA, where he leads their research as well as analysis-based stakeholder and policymaker engagement and education. White’s March 29 presentation is publicly available on YouTube and at ANS’s publication platform Nuclear Science and Technology Open Research (NSTOR).
RP3C chair N. Prasad Kadambi opened the CoP with brief introductory remarks about the RP3C before he welcomed White as the session’s presenter.
White covered three main topics: the history of the existing regulatory frameworks for new reactors, progress to date on the development of the Part 53 rule for advanced reactors, and the current status and next steps for the Part 53 rulemaking process.
C. D. Bowman, E. G. Bilpuch, D. C. Bowman, A. S. Crowell, C. R. Howell, K. McCabe, G. A. Smith, A. P. Tonchev, W. Tornow, V. Violet, R. B. Vogelaar, R. L. Walter, J. Yingling
Nuclear Science and Engineering | Volume 161 | Number 1 | January 2009 | Pages 68-77
Technical Paper | doi.org/10.13182/NSE161-68
Articles are hosted by Taylor and Francis Online.
The results of two experiments combined show that the diffusion length D for thermal neutrons in the graphite studied is 24% larger than expected from classical experiments and that the boron equivalent absorption is smaller than expected and consistent with zero. Taken together, the results indicate a reduction in parasitic thermal neutron absorption in heterogeneous graphite reactors by about 30%. The first experiment measured the z-dependence of thermal neutron flux in a column of 12 t of granular graphite with a neutron source at the bottom. A second measurement was made by pulsing the column with a neutron source at its center and measuring the neutron decay rate as a function of time after a pure exponential decay had been established. The diffusion coefficient D adjusted to a density of 1.60 g/cm3 is 1.05 ± 0.03 cm compared with the commonly accepted value of 0.85 ± 0.013 cm. The absorption in our graphite owing to impurities was found to be <10% of that from carbon alone. The parameter a/D that measures neutron loss was determined to be 0.000235 ± 0.000026 cm-2 for a density of 1.60 g/cm3 and may be compared with the commonly accepted value of 0.000340. The performance of graphite thermal spectrum reactors constructed using our graphite would be significantly enhanced over present expectations because neutron loss to graphite is a major factor in the neutron economy of graphite-moderated thermal reactors.