ML20038C555
| ML20038C555 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 12/04/1981 |
| From: | Devincentis J PUBLIC SERVICE CO. OF NEW HAMPSHIRE |
| To: | Miraglia F Office of Nuclear Reactor Regulation |
| References | |
| SBN-198, NUDOCS 8112110215 | |
| Download: ML20038C555 (2) | |
Text
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SE/N00KSTATION Engineering Office:
1671 Worcester Road Framingham, MA 01701
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United Sta tes Nuclear Regulatory Commission Washington, D. C.
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A t ten tion :
Mr. Frank J. Miraglia, Chie f M
Licensing Branch #3 Division of Licensing
References:
(a) Cons truction Permits CPPR-135 and CPPR-136 Docket Nos. 50-443 and 50-444 (b) USNRC Letter, dated October 30,1981, " Auxiliary (Emergency) Feedwater System Reliability,"
F. J. Miraglia to W. C. Tallman
Subject:
Seabrook Sta tion Emergency Feedwa ter System Reliability
Dear Mr. Miraglia :
Reference (b) stated that it is the Staff's position that in order to achieve the desired goal of Emergency Feedwater (EFW) System reliability, a two pump EFW System would not be considered acceptable. A three pump system, with at least two of these pumps and their associated trains being safety grade, would be required to provide the necessary availability. Additionally, Reference (b) ackno#. edged that the Seabrook design utilizes a two pump safety grade EFW System and also a non-safety grade Startup Feedwater (SUF) pump in parallel with the two EFW pumps. However, it did not appear that the SUF pump could be powered by an emergency bus.
It has been, and is, Seabrook's position that the existing two pump safety grade EFW System, with its inherent diversity and redundancy, provides acceptable availability and reliability. However, during the design phase, it was felt prudent to maximize the flexibility of the SUF pump and provide for an alterna te power source for the unlikely occurence of multiple failures which would render the existing EFW System inoperable.
The normal power supply for the SUF pump is the 4160 V ac non-emergency bus 4 as depicted in FSAR Figure 8.3-7.
Although not described in the FSAR section (10.4.12) which addresses the SUF pump, provisions were made in the system design for an alternate power supply from an emergency bus.
FSAR Figure 8.3-8 shows the alternate power supply for the SUF pump from the 4160 V ac emergency go f o
8112110215 811204' f
PDR ADOCK 05000443 hi A
Mr. Frank I. Miraglia, Chief December 4,1981 Page 2 bus E-5.
The alternate power supply cubicle in bus E-5 shares the power supply breaker with the normal feed in bus 4.
Under loss of off-site power conditions, emergency bus E-5 is powered by emergency diesel generator DG-1A.
The manual action of transferring the power supply breaker from the non-emergency bus 4 to the emergency bus E-5 and the required manual valve alignments will be controlled by detailed emergency procedures. Before the SUF pump can be started, the operator must also assess the need to temporarily shed loads from the diesel generator DG-1A.
Because the Seabrook Statioa Emergency Feedwater System design does provide for three diverse, full capacity pumps (two of which are safety grade), it is our position thet the concerns expressed in Reference (b) have been satisfactorily addressed.
A prompt re-evaluation of our design utilizing this clarifying information would be greatly appreciated. Please contact this office should you require supplemental information.
Very t.ruly yours, YANKEE ATOMIC ELECTRIC COMPANY
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John DeVincentis s,/ Project Manager l
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