Joint Assessment of Cable Damage and Quantification of Effects from Fire (JACQUE-FIRE), Volume 1: Phenomena Identification and Ranking Table (PIRT) Exercise for Nuclear Power Plant Fire-Induced Electrical Circuit Failure.

摘要

Volume 1 of this report documents the results of a Phenomena Identification and Ranking Table (PIRT) exercise that was undertaken on fire-induced electrical circuit failures that may occur in nuclear power plants when cables are damaged by fires. Volume 2 documents the PRA expert elicitation results and will include the best estimate conditional probabilities of hot short-induced spurious operations of control circuits, given fire damage to associated cables. This program was sponsored by the U.S. Nuclear Regulatory Commissions (NRCs) Office of Nuclear Regulatory Research (RES) and the Electric Power Research Institute (EPRI) under the NRCRES/ EPRI Memorandum of Understanding (MOU) collaborative research agreement. The electrical expert PIRT panel (herein referred to as the PIRT panel) was comprised of a group of experts sponsored equally by NRC and EPRI. Staff from Brookhaven National Laboratory (BNL) facilitated the efforts of the PIRT panel. The objective of this PIRT was to identify phenomena that can affect the fire-induced failure modes of electrical circuits after cables are damaged by fire. The PIRT panel used the results from recent fire tests performed by the Nuclear Energy Institute (NEI), EPRI and NRC, identifying and ranking the parameters that can influence the hot short induced failure modes of electrical control circuits. Using these influencing parameters, the results of cable-fire tests, expert judgment, and operating experience, the PIRT panel developed circuit configurations vulnerable to hot short induced circuit failure modes that can cause the spurious operation of certain end devices. In addition to completing the PIRT exercise on control circuits, the PIRT panel reached technical consensus on the majority of issues in analyzing fire protection circuits such as power-cabling consequential hot shorts, open circuits on the secondary of current transformers, and multiple high-impedance faults. The PIRT panel noted the lack of data on instrument circuits, including process monitoring indication, needed to support a structured evaluation of the influencing phenomena. The panel identified key areas for future research to advance the current knowledge base.