05000282/FIN-2009007-03
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Finding | |
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| Title | Sequential Starting of Fire Pumps |
| Description | An unresolved item (URI) concerning the starting sequence for the fire pumps was identified by the inspectors. The Prairie Island Nuclear Generating Plant fire pumps were arranged to start sequentially upon decreasing pressure in the fire protection system. Specifically, the electric driven screen wash pump would provide water to the fire protection system at 102 pounds per square inch gauge (psig), the electric driven fire pump would start at 95 psig, and the diesel driven fire pump would start at 90 psig. No time delays were incorporated into the pump starting circuits. The code of record for the fire pumps was National Fire Protection Association (NFPA) 20 1969, Standard for the Installation of Stationary Pumps for Fire Protection: Section 515.d.3 (applicable to electric driven pump controllers) and Section 715.d.3 (applicable to engine driven pump controllers) of NFPA 20 1969 both stated: Controllers for multiple pump units shall incorporate a sequential timing device to prevent any one pump starting simultaneously with any other pump. The inspectors noted that the explanatory language from Section 12.5.2.4 of the NFPA Handbook for Stationary Fire Pumps, second edition, stated, The sequence-starting requirement prevents excessive hydraulic stress to piping, control valves, and other system components during pump startup. The licensee did not believe that Sections 515.d.3 and 717.d.3 were applicable to their installation because the additional pumps were provided for redundancy as opposed to demand. Additionally, the licensee considered the starting of pumps using different pressure settings sufficient for sequential starting. The inspectors and the licensee mutually agreed to seek a formal code interpretation from NFPA with the following language concerning the current standard, NFPA 20 2007: Section 10.5.2.5 and Section 12.5.2.4 state, Sequence Starting of Pumps states The controller for each unit of multiple units shall incorporate a sequential timing device to prevent any one driver from starting simultaneously with any other driver. Background: A fire pump arrangement consists of redundant pumps connected in parallel. Each pump is designed to supply 100 percent of the required flow and pressure. The controllers for each pump are arranged to start at different pressure settings. Question 1: Is this configuration considered a multiple unit configuration covered by Sequential Starting of pumps in Section 10.5.2.5? Question 2: Is having controllers for each unit of multiple pump units set to actuate at different pressures considered sufficient to meet the requirement of Section 10.5.2.5 without incorporation of an additional sequential timing device? The inspectors noted that formal code interpretations posed to NFPA were required to be posed in the form of Yes or No questions and based on the current version of the NFPA code. This issue is considered an URI pending a formal interpretation from NFPA and NRC review. (URI 05000282/2009007-03; 05000306/2009007-03 |
| Site: | Prairie Island  |
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| Report | IR 05000282/2009007 Section 1R05 |
| Date counted | Jun 30, 2009 (2009Q2) |
| Type: | URI: |
| cornerstone | Barrier Integrity |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.05 |
| Inspectors (proximate) | R Langstaff R Orlikowski M Phalen K Stoedter D Jones L Haeg R Lerch P Zurawski D Betancourtm Munirr Daley R Langstaff R Winter |
| INPO aspect | |
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Finding - Prairie Island - IR 05000282/2009007 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Prairie Island) @ 2009Q2
Self-Identified List (Prairie Island)
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