05000528/FIN-2009006-09
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Finding | |
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| Title | Safety Injection Pump Full Flow Recirculation Potential Design Control Issue |
| Description | The inspectors identified an unresolved item (URI) regarding the potential failure of the containment spray and/or low pressure safety injection pumps during plant operations that put the refueling water tank in full flow recirculation. The inspectors reviewed PVAR 3284044 and identified two issues that potentially exist with the ability of the safety injection mini-flow lines to recirculate to there fueling water tank when a safety injection actuation signal is received during accident conditions with either the low pressure safety injection or containment spray pumps in full flow recirculation to the refueling water tank. In some system lineups, operations personnel use the full flow recirculation line to the refueling water tank by opening normally locked-closed manual valves. This full flow recirculation line uses the same return line back to the refueling water tank that the pump mini-flow lines use. The two scenarios of concern are: 1) One of the two containment spray pumps starts, but does not immediately inject into the reactor coolant system due to a small break loss of coolant accident. The head losses in the return line under full flow recirculation to the refueling water tank could induce sufficient backpressure in the mini-flow lines such that the other train of containment spray and both trains of low pressure safety injection potentially run dead-headed, or without any mini-flow. In a related issue, if one of the two low pressure safety injection pumps start, but do not inject immediately, the back pressure in the common recirculation line could dead-head the other train of low pressure safety injection. 2) A scenario in which there is a large break loss of coolant accident, and the refuelingwater tank depletes relatively quickly. If the manual valves associated with the full flow recirculation line are not shut, an unintended flow diversion out of containment back to the refueling water tank could occur after a recirculation actuation signal.NRC Bulletin No. 88-04, Potential Safety Related Pump Loss, described the potential for dead-heading one or more pumps in safety-related systems that have a common mini-flow line. This licensee\'s evaluation in response to the bulletin failed to consider all emergency core cooling system line-ups, resulting in a failure to evaluate the full flow recirculation lineup to the refueling water tank on the mini-flow lines. Discussions with the licensee and the Westinghouse indicated that this recently discovered information is potentially generic in nature. This URI is being opened to determine if a design control (or other) performance deficiency exists and to determine the significance of any identified performance deficiencies: URI 05000528;529;530/2009006-0 |
| Site: | Palo Verde  |
|---|---|
| Report | IR 05000528/2009006 Section 1R15 |
| Date counted | Mar 31, 2009 (2009Q1) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.15 |
| Inspectors (proximate) | R Treadway L Carson J Adams J Melfi S Alferink M Young M Hay J Bashore M Catts P Jayroe S Hedgern Taylord Dumbacher R Rodriguez E Knutson R Walton D Proulx D Bollock M Catts E Ruesch A Vegel H Freeman |
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Finding - Palo Verde - IR 05000528/2009006 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Palo Verde) @ 2009Q1
Self-Identified List (Palo Verde)
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