TY - GEN
T1 - 10 CFR 50.46c rulemaking
T2 - 16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2015
AU - Frepoli, Cesare
AU - Yurko, Joseph P.
AU - Szilard, Ronaldo H.
AU - Smith, Curtis L.
AU - Youngblood, Robert
N1 - Publisher Copyright:
© Copyright (2015) by American Nuclear Society All rights reserved.
PY - 2015
Y1 - 2015
N2 - The USNRC is considering a rulemaking that would revise requirements in 10 CFR 50.46 (aka the ECCS rule). Experimental work sponsored by the USNRC suggested that the current regulatory acceptance criteria on ECCS performance during design-basis accidents are actually nonconservative for higher burnup fuel: That embrittlement mechanisms not contemplated in the original criteria exist, and the 17% limit on oxidation is not adequate to preserve the level of ductility that the NRC originally deemed to be warranted for adequate protection. The new rule imposes new acceptance criteria, and is expected to be in effect as early as 2016. An implementation plan was developed which, once the rule is amended, will give individual plants up to 24, 48 or 60 months to comply, depending on the status of each plant's analysis of record, the effort involved, and existing analytical margin to the limits. The new rule may challenge US LWR fleet operational flexibility and economics. Within the DOE Light Water Reactor Sustainability (LWRS) Program, the INL is pursuing an initiative which is focused on industry applications using Risk-Informed Safety Margin Characterization (RISMC) tools and methods applied to issues that are of current interest to the operating fleet. The mission of RISMC is to provide cost-beneficial approaches to safety analysis by leveraging modern methods, augmented tools (a combination of existing and new), and repurposed data (existing, but used in a new way). The objectives of this paper are to revisit and redefine the LOCA problem in light of the new rule, to propose a novel, RISMC-based approach to risk-inform the licensees' response to this rulemaking, to fully characterize LOCA effects, and potentially to optimize operational flexibility under the new rule. The goal is a Risk-Informed Margin Management (RIMM) tool for the industry to cope with the challenges associated with the more restrictive LOCA rule, the 10 CFR 50.46c. Uncertainty analysis for the RIMM Integrated Evaluation Model (IEM) will be performed with algorithms derived from the machine learning community. These techniques will enable responsive sensitivity and optimization studies.
AB - The USNRC is considering a rulemaking that would revise requirements in 10 CFR 50.46 (aka the ECCS rule). Experimental work sponsored by the USNRC suggested that the current regulatory acceptance criteria on ECCS performance during design-basis accidents are actually nonconservative for higher burnup fuel: That embrittlement mechanisms not contemplated in the original criteria exist, and the 17% limit on oxidation is not adequate to preserve the level of ductility that the NRC originally deemed to be warranted for adequate protection. The new rule imposes new acceptance criteria, and is expected to be in effect as early as 2016. An implementation plan was developed which, once the rule is amended, will give individual plants up to 24, 48 or 60 months to comply, depending on the status of each plant's analysis of record, the effort involved, and existing analytical margin to the limits. The new rule may challenge US LWR fleet operational flexibility and economics. Within the DOE Light Water Reactor Sustainability (LWRS) Program, the INL is pursuing an initiative which is focused on industry applications using Risk-Informed Safety Margin Characterization (RISMC) tools and methods applied to issues that are of current interest to the operating fleet. The mission of RISMC is to provide cost-beneficial approaches to safety analysis by leveraging modern methods, augmented tools (a combination of existing and new), and repurposed data (existing, but used in a new way). The objectives of this paper are to revisit and redefine the LOCA problem in light of the new rule, to propose a novel, RISMC-based approach to risk-inform the licensees' response to this rulemaking, to fully characterize LOCA effects, and potentially to optimize operational flexibility under the new rule. The goal is a Risk-Informed Margin Management (RIMM) tool for the industry to cope with the challenges associated with the more restrictive LOCA rule, the 10 CFR 50.46c. Uncertainty analysis for the RIMM Integrated Evaluation Model (IEM) will be performed with algorithms derived from the machine learning community. These techniques will enable responsive sensitivity and optimization studies.
KW - 10 CFR 50.46
KW - LOCA
KW - RIMM
KW - RISMC
UR - http://www.scopus.com/inward/record.url?scp=84962724053&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:84962724053
T3 - International Topical Meeting on Nuclear Reactor Thermal Hydraulics 2015, NURETH 2015
SP - 2503
EP - 2516
BT - International Topical Meeting on Nuclear Reactor Thermal Hydraulics 2015, NURETH 2015
PB - American Nuclear Society
Y2 - 30 August 2015 through 4 September 2015
ER -