05000327/FIN-2008005-03
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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 Unit 1 and 2 TS 3.4.6.1, Leakage Detection Instrumentation, for the licensees failure to maintain the gaseous lower containment atmosphere radioactivity monitor of the RCS leakage detection instrumentation operable. The Unit 1 and 2 monitors were inoperable since June 1987 as a result of not being able to perform their safety function of detecting a reactor coolant pressure boundary leak of 1 gallon per minute in one hour due to improvements in reactor fuel quality. The NRC is exercising enforcement discretion not to 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. Description: On November 6, 2008, the inspectors, after consultation with the Office of Nuclear Reactor Regulation (NRR), informed the licensee that the gaseous lower containment atmosphere radioactivity monitor on both Units 1 and 2 were not operable. The licensee initiated PER 156667, declared the equipment inoperable, complied with the applicable actions of TS 3.4.6.1 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 December 4, 2008, which removed the requirement to maintain the gaseous channel of the containment atmosphere radiation monitors 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 gallon per minute (gpm) in one hour. This sensitivity was consistent with the information provided in 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 Sequoyah Units 1 and 2 were 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 these monitors 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 June 1987, calculation APS3-055, Reactor Coolant Pressure Boundary Leakage Detection with the Containment Lower Compartment Air Radiation Monitor, concluded that, for realistic RCS activity levels, the gaseous channel would not be capable of meeting the 1 gpm in one hour sensitivity. As discussed above, the licensee failed to recognize that not meeting the required sensitivity resulted in the gaseous lower containment atmosphere radioactivity monitors being inoperable. |
| Site: | Sequoyah  |
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| Report | IR 05000327/2008005 Section 1R15 |
| Date counted | Dec 31, 2008 (2008Q4) |
| Type: | Violation: Severity level Enforcement Discretion |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.15 |
| Inspectors (proximate) | H Gepford R Moore R Aiello C Young M Speck D Mas-Penaranda B Caballero C Even J Hamman J Eargle P Braxton |
| INPO aspect | |
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Finding - Sequoyah - IR 05000327/2008005 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Sequoyah) @ 2008Q4
Self-Identified List (Sequoyah)
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