ML20214T899
| ML20214T899 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 11/10/1986 |
| From: | Daltroff S PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| IEB-86-003, IEB-86-3, NUDOCS 8612090048 | |
| Download: ML20214T899 (3) | |
Text
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i PHILADELPHIA ELECTRIC COMPANY 2301 MARKET STREET P.O. BOX 8699 F'HILADELPHI A. PA.19101
3 November 10, 1986 SHIE S L DALTROFF ELECTRIC PRODUCTION Docket Nos. 50-277 50-278 Dr. Thomas E. Murley, Administrator Region I U.S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406
SUBJECT:
Response to IE Bulletin 86-03 Potential Failure of Multiple ECCS Pumps Due to Single Failure of Air-Operated Valve In Minimum Flow Recirculation Line - Dated October 8, 1986 Peach Bottom Atomic Power Station Units 2 and 3 f
Dear Dr. Murley:
The purpose of this letter is to provide the Philadelphia Electric Company (PECo) response to IE Bulletin 86-03 for Peach Bottom Atomic Power Station Units 2 and 3.
The bulletin discussed a situation at another nuclear power plant in i
which a single failure could result in the loss of minimum flow bypass for all Emergency Core Cooling System (ECCS) pumps in a system.
As indicated in the bulletin, this condition could result in no flow through the ECCS and could lead to the pumps running dead headed with potential for pump damage in a few minutes.
Since the finding for the first action required for the bulletin determined that Peach Bottom Units 2 and 3 are not vulnerable to these failures, items 2, 3 and 4 require no response.
The actions required by the bulletin are restated below followed by PECo's response:
4 1
1.
Promptly determine whether or not your facility has a i
single failure vulnerability in the minimum flow recirculation line of any ECCS pumps that could cause a failure of more than one ECCS train.
i 2.
If the problem exists, (a) promptly instruct all operating shifts of the problem and measures to recognize and mitigate the problem, (b) promptly develop and implement corrective actions which bring
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k() g your facility into compliance with GDC 35.
8612090048 861110 PDR ADOCK 05000277
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Dr. Thomas E. Murlcy November 10, 1986 Page 2
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- 3.
Within 30 days of receipt of this bulletin, (a) provide a written report to the NRC which identifies whether or not this problem exists at your facility
.(b)tif the problem exists (or existed) include in the report the justification for continued. operation and s
identify the short-term modifications to plant
' operating procedures or hardware that'have been or are being implemented to ensure safe plant operations.
4 4.
If the problem exists (or existed),. provide a written R
report within 90 days of receipt of this bulletin informing the NRC of the schedule for long-term resolution of this problem.
Response
The ECCS minimum _ flow logic has been reviewed for Peach Bottom Units 2 and 3 and it has been determined that the single failure condition discussed in I.E.Bulletin 86-03 does not exist.
.The minimum flow valves are motor-operated valves fed from'a sa'feguard electrical distribution system.
All ECCS systems have independent and redundant electrical safeguard divisions. 'The ECCS and RCIC systems are fed from four AC electrical safeguard divisions and two DC electrical safeguard divisions.
There are four 33 1/3 percent capacity Residual Heat Removal (RHR) pumps, four 50 percent capacity Core Spray (CS) pumps, one steam driven High Pressure Coolant Injection (HPCI) pump and one steam driven Reactor
~ Core Isolatici. Cooling (RCIC) pump.
One RHR pump and one core spray pump and their associated minimum flow valves are assigned to each AC electrical safeguard division.
Each HPCI and RCIC minimum flow valve is' assigned to opposite DC electrical safeguard divisions.
The loss of any one AC elecdrical safeguard motor control center would result in l
the loss of minimum flow valves for one RHR pump and one core spray pump.
This scenario is enveloped by the loss of one diesel generator along with its associated safeguard bus.
The loss of one diesel generator has previously been analyzed in the Updated Final Safety Analysis Report.
'The minimum flow return piping for each loop of any ECCS system is independent from any other ECCS minimum flow line.
This independence includes the required separation of electrical and control power as well as a physical separation between loops of ECCS.
All of the minimum flow lines return to the suppression pool and in some cases use a common header at the suppression pool penetration; however, from the minimum flow valves to the common header there are no shutoff valves, only check valves and restricting orifices.
There are no restrictions in the common header return to the suppression pool.
Therefore, there is no creditable single failure in the minimum flow recirculation lines which could disable more than one.ECCS pump.
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-Dr. Thomac E. Murley November 10, 1986 Page 3 The design of Peach Bottom Units 2 & 3 incorporates independence, both electrically and physically between the trains of ECCS, therefore, the facility is not vulnerable to a single failure which would disable more than one train of ECCS.
i Very truly
- ours,
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E L} /
cc:
T. P. Johnson, PB NRC Site Inspector I
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RECEIVED-REG 10Il 1 19831:0V 13 Pil 2: 49 4
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