ML20033A518
| ML20033A518 | |
| Person / Time | |
|---|---|
| Site: | McGuire  |
| Issue date: | 11/13/1981 |
| From: | Parker W DUKE POWER CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| NUDOCS 8111250525 | |
| Download: ML20033A518 (3) | |
Text
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o DUKE POWER CUM,1?@ggy q Powsu llen.oisd l NTA, G: ;-
m Sourn Curuen STHEET, CnAIMDTTE, N. G. 2aa m UI NOV 20 A S. 53 wlLLI AM O. PAR M E R J R.
Ver Persiorm, TgttPeeQNEl AR E A 704 November 13, 1981
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Mr. J. P. O'Reilly, Director db I'if,rs U. S. Nuclear Regulatory Commission p
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Re: McGuire Nuclear Station Unit 1 Docket No. 50-369
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Dear Mr. O'Reilly:
Please find attached a special report submitted pursuant to Technical Speci-fication 6.9.2.
This report concerns violation of T.S.3.7.10.1, "The Fire Suppression Water System Shall be Operable With:
The actions tak-en described in the report will ensure the safe operation of the plant and the health and safety of the public.
Very truly yours, AC i
/
William O. Parker, Jr.
PBN/sch Attachment cc: Director Records Center Office of Management and Program Analysis Institute of Nuclear Power Operations U. S. Nuclear Regulatory Commission 1820 Water Place Washington, D. C.
20555 Atlanta, Georgia 30339 Ms. M. J. Graham Resident Inspector-NRC McGuire Nuclear Station 091CTAL COM 811125')525 811113 PDR ADOCK 05000369 d
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c McGUIRE NUCLEAR STATION SPECIAL REPORT REPORT DATE: November 13, 1981 OCCURRENCE DATE:
October 28, 1981 FACILITY: McGuire Unit 1; Cornelius, N.C.
IDENTIFICATION OF OCCURRENCE: A mechanical joint separated on the fire pro-
- tection (RY) system piping located on the condenser intake structure.
CONDITIONS PRIOR TO OCCURRENCE: Mode 1; 30% power, conducting low power testing.
DESCRIPTION OF OCCURRENCE: On October 28, 1981 a large water spout was discovered on the main intake structure.
It was noticed that all three main fire pumps were running and that fire header pressure was approximately 50 psig (150 psig is nor-mal). Since the intake structure leak was in underground piping, various sections of the RY system were isolated. While doing this, the three fire pumps from the RY supply header were isolated for approximately twenty minutes. This was repor-table pursuant to Technical Specification 3.7.10.1.
APPARENT CAUSE OF OCCURRENCE: The cause of the incident was the separation of a mechanical joint in the 16 inch diameter RY piping located approximately four feet underground.
The two 3/4 inch diameter tie rods which held the joint together broke.
The stress mechanism causing the failure of the tie rods could not be determined.
ANALYSIS OF OCCUFRENCE:
Main fire pump A (2500 gpm at 150 psig) had been running for several hours prior to the incident and was maintaining fire header pressure at ap-proximately 150 psig. At about 1653 hours0.0191 days <br />0.459 hours <br />0.00273 weeks <br />6.289665e-4 months <br />, fire pumps B and C started automaticel-ly (85 and 75 psig, respectively) due to decreasing header pressure. The leak was isolated at approximately 1725 hours0.02 days <br />0.479 hours <br />0.00285 weeks <br />6.563625e-4 months <br /> and fire pump A was realigned to the fire header at about 1745. Fire pump C was also realigned and available as a backup if needed.
The RY piping flange which separated was located between two 90 elbows approximately four feet underground. The flange (American Cast Iron) was 150 psig cast-iron 16 inch diameter water piping and consirted of a male-female standard mechanical joint held together by two 3/4 inch diameter steel tie rods.
On October 27, the three fire pumps were flow tested as part of the annual Nuclear Mutual Limited fire protection system inspection.
Each of the pumps was dead headed as part of its flow test. The affected flange was part of the piping which had to be isolated for the flow test of fire pump B.
During the test, the shutoff head of the pump reached approximately 190 psig.
The fire pumps were dead headed approximately two years ago during the fire protec-tion preoperational test.
This past summer they were dead headed during an eighteen month periodic test and again on October 27.
There was no indication of any RY pip-ing damage until October 28, however. The flange was repaired and four extra tie rods (six total) wtre added.
The flange was in-service leak tested at approximately 150 psig on October 31.
SAFETY ANALYSIS: During the twenty minutes that the fire pumps were unavailable, the two jockey pumps (200 gpm each at 120 psig) which take a suction from the condenser circulating water piping could have been used to fight a small fire, had one devel-
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Rdport Number 81-166-
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Their ability to fight a major. fire would have been limited due to their
-relatively small capacity..However, no fire developed and thus, the health and safety of the public were not affected by this incident.
CORRECTIVE ACTION: The leak was isolated and the separated flange repaired and in-service leak tested..Any fire pump flow tests which will be performed in the future will be done without dead heading the fire pumps.- The highest pressure.
'which will be used during the tests will be approximately 145 psig..
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