05000321/FIN-2009006-04
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Finding | |
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| Title | Reactor Building Equipment Drain Sump System for Units 1 and 2 |
| Description | The team identified an Unresolved Item (URI) regarding the licensees failure to scope and monitor the Reactor Building Equipment Drain Sump System for Units 1 and 2 in the maintenance rule program. The torus room and the reactor building diagonal rooms are equipped with instrumented floor drain sumps. The diagonal rooms house the High Pressure Core Injection (HPCI), Reactor Core Injection Cooling (RCIC), Control Rod Drive, Core Spray, and RHR pumps. The instrumented sumps are isolatable from each other by means of air operated valves (AOV). Automatic closure of the normally open AOVs isolates the reactor building diagonal rooms, which prevents the spread of water from room to room. The AOVs are automatically closed when high water levels are detected by sump level switches. FSAR, Section 9.3.3, states in part that a single failure of a level switch will not prevent sump isolation from occurring. The team determined that the licensee failed to scope and monitor the Reactor Building Equipment Drain Sump System in their maintenance rule program since 1996. The teams preliminary review of corrective action documents, surveillance records, and work orders revealed a lack of functional testing on Unit 1, repetitive failures of AOVs during weekly surveillance testing on both Units 1 and 2, and inadequate corrective actions for repetitive AOV failures. Additionally, the teams questioning revealed that the design of the level switches did not meet the single failure criteria as stated in FSAR Section 9.3.3.The team determined that the licensees flood analysis did not account for a single failure of the level switches; therefore, the flood analysis did not evaluate the effects of flooding in the diagonal rooms of Units 1 and 2.As a result of the teams observations, the licensee completed Engineering Response, RER C091204801, Flooding of Torus Room and Diagonals, during the inspection. RERC091204801, determined that a main feedwater line break with a postulated single failure of: Unit 1 level switch (1T45-N007) would result in the loss of RCIC system, and Unit 2 level switches (2T45-N006 or 2T45-N007), would result in the loss of the HPCI system or RCIC systems. The licensee initiated CRs (2009105744, 2009105110,2009105111, 2009105615, and 2009105727) and administratively closed the AOVs as an interim compensatory measure. This issue is unresolved pending further inspection and interface with the licensee to determine the extent of condition and impact from the failure to scope and monitor the Reactor Building Equipment Drain Sump System in the licensees maintenance rule program, and the single failure design deficiency for the level switches. (URI 05000321/2009006-04 and 05000366/2009006-04, Reactor Building Equipment Drain Sump System for Units 1 and 2) |
| Site: | Hatch  |
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| Report | IR 05000321/2009006 Section 1R21 |
| Date counted | Sep 30, 2009 (2009Q3) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21 |
| Inspectors (proximate) | C Smith C Baron D Jones G Skinner R Lewis J Hamman B Desai R Williams J Eargle A Senguptab Caballerod Jones E Morris G Macdonald J Eargle P Niebaum S Shaeffer |
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Finding - Hatch - IR 05000321/2009006 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Hatch) @ 2009Q3
Self-Identified List (Hatch)
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