05000280/LER-1982-055

LER 82-055/03L-0:on 820429,MDP 21.3 Revealed That Control Room Envelope Might Not Meet Tech Spec Requirements.Caused by Leak in Door Seals & Improper Exterior Ventilation Lineup.Seals Replaced & Lineup Corrected

ML20054E490
Person / Time
Site:	Surry
Issue date:	05/28/1982
From:	Joshua Wilson VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20054E485	List: 05000280/LER-1982-025 05000280/LER-1982-055 05000280/LER-1982-063 ML20054E484
References
LER-82-055-03L, LER-82-55-3L, NUDOCS 8206110271
Download: ML20054E490 (3)

LER-2082-055,

Event date:
Report date:
2802082055R00 - NRC Website

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On April 29. 1982. with Unit 1 & Unit 2 at full power. MOP 21.3 revcaled that the j Control Room envelope might not maintain a positive differential pressure of .05  :

2e1 I inches of water. This event occurred again on April 30, May 1 and May 2, 1982. ]

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it j i ventilation system remained operable and the cont-ol room pressure envelope was j

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' penetrations. The door seals were replaced and the exterior ventilation line up

<i corrected. A Special Test is being performed to inspect and upgrade as necessary i

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5TTitCIEET.1 SUPRY POWER SIRTICN, UNIT 10.1 UDCKLT NO. 50-280 REPORT 10. 82-055/03I,-0 EVENT DATE: 04-29-82 TITLE OF TIE EVENT: Excessive Control Rocm Icakage

1. DESCRIPTION OF TIE EVENT:

On April 29, 1982 with Unit 1 & Unit 2 at full pcuer, M3P 21.3 (Control Rocm Pressure 'Ibst) was performed with unsatisfactory results. Doors to the pressure envelope were temporarily sealed and the Maintenance Operating Procedure was then satisfactorily completed. Similar events occurred again on April 30, May 1 and May 2, 1982. W ese eventa indicated that the Control Rom pressure envelope might not be capable of rraintaining a positive differential pressure of .05 inches of water with air supplied by the mergency bottled air systs. Wese events are contrary to Technical Specification 3.19.A and are reportable per Technical Specification 6.6.2.b. (2) .

) 2. PROBABLE CJNSEQUENCES: ,

he requirem2nt for the Control Rocm pressure envelope to be capable of maintaining a positive differential pressure of .05 inches of water insures that the bottled air systs is sufficient to prevent any inleakage for a period of one hour following a Ioss of Ccolant Accident. W e mergency

ventilation system remained operable and the Control Rocm Pressure boundary was returned to satisfactory condition following each event, within the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Tech. Spec. time limit. h erefore, the health and safety of the public wre not affected.

3. CAUSE:

! W e cause of the events has been attributed to excessive leakage through Control Rocm envelope fire doors and through sealed electrical penetrations 4 betwen the Emergency Switchgear rocas and the cable vaults, his leakage was further aggravated by an imaw er ventilation line up in the cable vaults. A negative pressure was developed due to closed fire doors preventing the normal supply ventilation flow to the cable vault exhaust fans.

4. IMMEDIATE 03RRtL'rn'E ACTION:

he emergency ventilation system was verified operational and an imnediate investigation was initiated to determine the source of the leakage.

5. SUBSEQUENT CORN. ACTION:

For the April 29th and 30th event, all leaking control rocm doors were repaired and a satisfactory test was performed.

i During the May 1 event, interim rreasures ware taken which yielded test results that were not considered to be degrading to safety for the short term and also to demonstrate that the pressure envelope was capable of performing its intended function. Hwever, it was also' recognized at this time that the envelope still contained leakage which would have to be corrected in order for it to be considered fully acceptable. .

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Page 2 Report No. 82-055/03L-0 On May 2nd, an improper ventilation line up for the cable vault was discovered and verified to be aggravating the leakage. After properly aligning the cable vault ventilation, the envelope pressure test was conducted satisfactorily.

6. ACTION TAKEN TO PREVENT' RECURRENCE:

A Special Test, ST-140 (Control / Relay Room Penetration Test) has been written and is being performed to check all control room envelope penetrations to ensure air tightness and upgrade any which are discovered to be degraded. The fire doors which were inhibiting normal ventilation flow through the cable vault areas have been placed in a normally opened position with automatic closure devices. The doors have also been labeled to reflect this requirement. In addition, improved quality doors'are being procured for installation in the critical envelope openings.

7. GENERIC IMPLICATIONS:

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