05000390/FIN-2008005-07
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Finding | |
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| Title | Technical Specification for the Containment Gaseous Radiation Monitors |
| Description | The inspectors identified a violation of TS 3.4.15, RCS Leakage Detection Instrumentation, for the licensees failure to maintain the gaseous lower containment atmosphere radioactivity monitor of the RCS leakage detection instrumentation operable. The monitor had been inoperable since May 2000 as a result of not being able to perform its safety function of detecting a reactor coolant pressure boundary leak of 1 gallon per minute (gpm) in one hour due to improvements in reactor fuel quality. The NRC is exercising enforcement discretion to not issue enforcement action for this violation in accordance with Enforcement Guidance Memorandum (EGM) 09-001, Dispositioning Violations of NRC Requirements for Operability of Gaseous Monitors for Reactor Coolant System Leakage Detection. On October 31, 2008, the inspectors, after consultation with the Office of Nuclear Reactor Regulation (NRR), informed the licensee that the gaseous lower containment atmosphere radioactivity was not operable. The licensee initiated PER 155844, declared the equipment inoperable, complied with the applicable actions of TS 3.4.15 which allowed up to 30 days of continued operation with compensatory actions in place, and submitted a license amendment request to change the TS. The TS amendment was issued on November 25, 2008, which removed the requirement to maintain the gaseous channel of the containment atmosphere radiation monitor as a method of RCS leakage detection. NRR determined that the technical bases for the gaseous lower containment atmosphere radioactivity monitor to be operable included sufficient sensitivity to detect a reactor coolant pressure boundary leak of 1 gpm in one hour. This sensitivity was consistent with the information provided in NRC Information Notice (IN) 2005-024, Nonconservatism in Leak Detection Sensitivity. This IN informed licensees that the 0.1-percent failed fuel assumption (original source term for sensitivity calculations) introduced a nonconservatism into the TS. However, the licensing bases for Watts Bar Unit 1 was not clear, in that, the licensing basis documents acknowledged that, for fuel with little or no defects, this sensitivity would not be expected. NRR considered that this circumstance would only occur immediately after initial plant startup. However, the licensee mistakenly concluded that the monitor would likewise be considered operable any time that fuel with little or no defects was again in use, e. g., due to improved fuel quality. In May 2000, the licensee developed calculation WBNTSR-062, Requirements for the Containment Upper and Lower Compartment Radiation Monitors, which concluded that for realistic RCS activity levels, the gaseous channel would not be capable of meeting the RG 1.45 detection sensitivity requirements. The UFSAR was revised to reflect this result and the change was submitted to the NRC as part of its normal periodic update. This conclusion was recently referenced in DCN 52631, dated June 20, 2008. In both cases, the licensee failed to recognize that not meeting the required sensitivity resulted in the gaseous lower containment atmosphere radioactivity monitors being inoperable. Contributing to the failure to recognize this issue in June 2008 was the licensees mistaken perception that since the NRC had been informed of the change by an UFSAR update, the change must have been acceptable. |
| Site: | Watts Bar  |
|---|---|
| Report | IR 05000390/2008005 Section 1R18 |
| Date counted | Dec 31, 2008 (2008Q4) |
| Type: | Violation: Severity level Enforcement Discretion |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.18 |
| Inspectors (proximate) | R Monk R Rodriguez H Gepford L Miller R Aiello M Pribish C Peabody B Caballero |
| INPO aspect | |
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Finding - Watts Bar - IR 05000390/2008005 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Watts Bar) @ 2008Q4
Self-Identified List (Watts Bar)
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