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NRC adopts ROP updates
The Nuclear Regulatory Commission has approved a significant overhaul of its Reactor Oversight Process (ROP) baseline inspection program that stresses a leaner, more risk-focused inspection process.
This adoption comes just over a month after NRC officials published their findings on the proposed ROP changes. The changes would reduce the number of hours spent annually on direct inspections at U.S. nuclear power plants by 38 percent.
Dong Hyuk Lee, Hyung Jin Shim, Chang Hyo Kim
Nuclear Science and Engineering | Volume 187 | Number 2 | August 2017 | Pages 154-165
Technical Paper | doi.org/10.1080/00295639.2017.1307031
Articles are hosted by Taylor and Francis Online.
The continuous-energy Monte Carlo (MC) sensitivity and uncertainty (S/U) analysis conducted using the multigroup covariance matrices has a theoretical pitfall in that it is inconsistent with the principle of continuous-energy MC neutronics calculations because the use of the multigroup covariance matrices means treating covariance data as multigroup variables rather than continuous-energy variables. As a way to get around this deficiency and perform the MC S/U analysis on the theoretically consistent principle, this paper presents a new continuous-energy MC S/U formulation which directly utilizes the continuous-energy covariance data in the evaluated nuclear data libraries instead of the multigroup covariance matrices produced by nuclear data processing codes. The validity of the new MC S/U formulation is examined in terms of the input-nuclear-data-induced k uncertainty of the Godiva critical assembly and the TMI-1 pin cell problem by inputting the continuous-energy covariance data of nuclides involved directly into the continuous-energy MC transport calculations by a Seoul National University MC code, McCARD.