05000369/LER-1981-052, Forwards LER 81-052/03L-0.Detailed Event Analysis Encl

Forwards LER 81-052/03L-0.Detailed Event Analysis Encl

ML20009C235
Person / Time
Site:	McGuire
Issue date:	05/12/1981
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20009C237	List: 05000369/LER-1981-052, Forwards LER 81-052/03L-0.Detailed Event Analysis Encl 05000369/LER-1981-052-03, /03L-0:on 810412,while in Mode 3,upper Head Injection Diaphragm Between water-filled & Nitrogen Bearing Accumulators Was Ruptured.Caused by Procedural Deficiency. Procedure Modified.Diaphragm Will Be Replaced
References
NUDOCS 8107200398
Download: ML20009C235 (3)

LER-1981-052, Forwards LER 81-052/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
3691981052R00 - NRC Website

text

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May 12, 1981 373-4o.3

'f Mr. James P. O'Reilly, Director h'\\NLJ.,)I[(Y

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U.S. Nuclear Regulatory Commission (bUf Region II 101 Marietta Street, Suite 3100 g

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Re: McGuire Nuclear Station Unit 1 Docket No. 50-369 j

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Dear Mr. O'Reilly:

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Please find attached Reportable Occurrence Report R0-369/81-52. This report concerns the UHI diaphragm in the Cafety injection System being ruptured. This incident was considered to be of no significance with respect to the health and safety of the public.

Ver truly yours, I

L2.

_f, William O. Parker, Jr.

RWO:pw Attachment

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cc: Director Mr. Bill Lavallee Office of Management & Program Analysis Nuclear Safety Analysis Center U.S. Nuclear Regulatory Commission Post Office Box 10412 Washington, D. C.

20555 Palo Alto, CA 94303 M

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il 8107200398 810512 PDR ADOCK 05000369 S

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McGUIRE NUCLEAR STATION INCIDENT REPORT Report Number:

81-52 Report Date:

April 27, 1981 Occurrence Date: April 12, 1981 Facility: McGuire Unit 1, Cornelius, N.C.

Identification of Occurrence: Upper Head Injection (UHI) diaphragm in the Safety Injection (NI) System ruptured.

Conditions Prior to Occurrence: Mode 3, Hot Standby Description of Occurrence: Approximately two hours after opening the UHI block valves and declaring the UHI system operable, the UHI rupture diaphragm alarm was received in the Control Room. Further investigation revealed that the diaphragm had ruptured.

Since it could not be determined how long the total dissolved nitrogen in the water accumulator would be within Technical Specification Sur-veillance Requirement 4.5.1.2c, it was decided that this was reportable pursuant to Technical Specification 3.5.1.2.

Apparent Cause of Occurrence: The Operating Procedure, Upper Head Injection, did not contain steps to fill and vent -the piping between the UHI discharge block valves prior to opening the valves.

Analysis of Occurrence: On April 12, 1981, the Operating Procedure, Upper Head Injection,was being used to fill and vent the piping between the UHI water ac-cumulator discharge block valves and the reactor vessel head. At approximately 1630 hours0.0189 days <br />0.453 hours <br />0.0027 weeks <br />6.20215e-4 months <br />, the UHI discharge block valves were opened to declare the UHI system operable so that Reactor Coolant System (NC) pressure could be increased above 1900 psig.

Immediately, a decrease of approximately 50 psig and a 20 percent r

i level decrease occurred in the UHI surge tank.

The drain on the standpipe feeding the level switch which gives the membrane rupture alarm was opened.

There was very little water and mostly a vapor / gas mixture in the standpipe.

Since it didn' t appear that the diaphragm had ruptured, NC pressure was increased.

At approximately 1830 hours0.0212 days <br />0.508 hours <br />0.00303 weeks <br />6.96315e-4 months <br />, the "UHI Membrane Leakage" alarm in the Control Room was received.

The drain on the standpipe was opened and about 10 gallons of water drained out.

The Operating Procedure, Annunciator Response for Panel 1AD8, required no immediate action be taken for a diaphragm leak and its sup-plementary action required a vork request be initiated to replace the diaphragm during the next plant shutdown.

In addition, Technical Specification 3.5.1.2 does not address the problem of a leaking diaphragm.

The Shift Supervisor also believed that only a small leak had occurred and thus, NC System pressure was increased further.

The decision was made to decrease NC System pressure to 1800 psig and replace the diaphragt since it could not be determined how quickly nitrogen would saturate the water in the accumulator.

t I

s Report Number 81-52 Page 2 After the diaphragm was replaced, at 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> on April 15, 1981, a sample wastakenfromthenormalpointatthebottomofthewatergccumulatorand the nitrogen concentration was found to be 99.6 SCF/1800 ft water.

Since TechnicalSgecification4.5.1.2requiresaconcentrationoflessthan80 SCF/1800 ft the decision was made to feed and bleed the accumulator to get it back into specification.

This was accomplished by feeding (15 gpm) from andbleedingtotheRefuelingWaterStorageTank(FWST)usingthgNIpump.

At 0600 hours0.00694 days <br />0.167 hours <br />9.920635e-4 weeks <br />2.283e-4 months <br /> on April 16, 1981,. a sample showed 102 SCF/1800 ft A sample wagtakenatthetopoftheaccumulatorat 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> and showed 63 SCF/1800 ft It was decided that there was a dead spot in the bottom of the tank where the normal sample was taken and the top sample was more representative of the tank contents.

Thus, the Technical Specification requirement (80 3

SCF/1800 ft ) was met, the feed and bleed was stopped, and NC pressurization was resumed. The UHI discharge block valves werc opened without incident.

When the NC System normal pressure of 2235 psig ras reached, the feed and j

bleed was restarted.

Finally, on April 17, 1981 a top sample was taken at 0900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br /> and showed 53.7 SCF/1800 ft3 and a bottom sample at 1045 hours0.0121 days <br />0.29 hours <br />0.00173 weeks <br />3.976225e-4 months <br /> indicated 3

56.8 SCF/1800 ft

Safety Analysis

Since there was only new fuel in the core, plant safety and the health and safety of the public were not affected by the rupture of the diaphragm.

If the reactor had been at power, the UHI System would still have been operable since the diaphragm is designed to rupture when the system is actuated anyway.

In this case, thenitrogensaturatedthewaterintheaccumulatorquickerthag expected since a bottom sample taken on Apr.118, 1981 showed 42.8 SCF/1800 ft The Operating Procedure, Annunciator Response for Panel 1AD8 (IAD8-F6, UHI Membrane Leakage), is being etudied to determine what further action is needed to insure that the Technical Specification requirement of less than 80 SCF/1800 ft3 is met if a diaphragm leak should occur during power operation.

Corrective Action

A change was issued to the Oparating Procedure, Upper Head Injection, to fill and vent the piping between the UHI discharge block valves.

This should prevent a rapid change in the water volume in the water accumulator and surge tank when the UHI System is put into operation.

I 1