05000280/LER-1987-001, :on 861223,pressurizer PORVs Declared Inoperable Due to Excessive Stroke Time.Caused by Insufficient Air Flow Due to Air Line Size.Air Lines Will Be Replaced W/Larger Tubing

:on 861223,pressurizer PORVs Declared Inoperable Due to Excessive Stroke Time.Caused by Insufficient Air Flow Due to Air Line Size.Air Lines Will Be Replaced W/Larger Tubing

ML20212R237
Person / Time
Site:	Surry
Issue date:	01/22/1987
From:	Saunders R VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
86-061, 86-61, LER-87-001, LER-87-1, NUDOCS 8702020560
Download: ML20212R237 (4)

LER-1987-001, on 861223,pressurizer PORVs Declared Inoperable Due to Excessive Stroke Time.Caused by Insufficient Air Flow Due to Air Line Size.Air Lines Will Be Replaced W/Larger Tubing

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(vii), Common Cause Inoperability
2801987001R00 - NRC Website

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no A T A ACT n-, e.oo e.oo e...~.,,-.,0 us,,,0.e.=o,.e., p oi On December 23, 1986, both Unit 1 and Unit 2 were at cold shut-down with their reactor coolant systems depressurized to atmos-pheric.

Unit 2 Pressurizer PORVs, PCV-2455C and PCV-2456 f ailed to open within the maximum allowabic stroke time when using the backup air supply in accordance with a Periodic Test.

On Janu-ary 2, 1987, with both Units still at cold shutdown and depressu-rized, the Unit 1 Pressurizer PORV, PCV-1455C failed to open i

within the maximum allowable stroke time similar to the Unit 2 l

valves. These valves were declared inoperable when the cycessive stroke times were discovered, and they were lef t in the open position in accordance with Technical Specification 3.1.G.

This was the first time these valves had been tested by this Periodic Test, which was written to test the backup air supply in response to IEIN 86-50.

The excessive stroke times were caused by insuf-ficient air flow due to air line size. The air lines and associ-ated components will he replaced with larger tubing and components.

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vtan SURRY POWER STATION, UNIT 1 0 l5 l0 l0 l0 l 2l8 l 0 8l7 0 l 0l 1 0l0 0l2 OF 0l3 textinm N w wo-wmicr.=assrsmn 1.0 Description of the Event On December 23, 1986, both Unit I and Unit 2 were at cold shutdown (CSD) and the reactor coolant systems depressurized to atmospheric pressure. Unit 2 Pressurizer PORVs, PCV-2455C and PCV-2456 (EIIS-PCV) failed to open within the maximum allowable stroke time when using the backup high pressure air supply bottles in accordance with a Periodic Test.

On January 2, 1987, with Unit I and Unit 2 at CSD and depressurized, the Unit 1 Pressurizer PORV PCV-1455C failed to open within the maximum allowable stroke time similar to the Unit 2 valves. PORV PCV-1456 was inoperable at the time of the test on PCV-1455C. These valves were declared inoperable at the time the excessive stroke times were discovered and they were left open in accordance with Technical Specification (T.S.)

3.1.C.

These PORVs provide Overpressure Mitigation Protection for the Reactor Coolant System (RCS) when the RCS is less than 350 degrees Fahrenheit. The backup air supply for these PORVs is the safety related air supply and consists of high pressure air bottles, air pressure regulators, SOVs and instrument air tubing. The Periodic Test that found these PORVs to have excessive stroke time, is a new Periodic Test that was written in response to ICIN 86-50 to specifically test the backup air supply. This was the first time this Periodic Test was performed on either Unit. These events are being reported in accordance with the requirements of 10CFR 50.73(a) (2) (vii).

2.0

Safety Consequences and Implications

When the reactor coolant average temperature is less than 350 degrees Fahrenheit and the Reactor Vessel head is bolted, the oper-ability of two PORVs, or the RCS vented through an open PORV, en-sure that the Reactor Vessel will be protected from pressure transients which could exceed the limits of Appendix G to 10CFR 50.

When the Reactor Coolant average temperature is greater than 350 degrees Fahrenheit, overpressure protection is provided by a bubble in the pressurizer and/or pressurizer safety valves.

When the PORVs were determined to have excessive stroke time, they were placed in the open position to provide a vent path for the RCS in accordance with Technical Specification 3.1.C.

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The PORVs that were declared inoperable did cycle, although the time to cycle exceeded the required time by a maximum of 5.81 seconds. There were no RCS pressure transients that these valves would have had to responded to during the existing Unit outages.

Therefore, these events did not constitute an unreviewed safety question and the health and safety of the public were not affected.

3.0 Cause

The air supply lines to the valve operators from the backup high pressure air bottles are undersized. This has restricted the air flow to the valve to less than the minimum air flow required to open the valves within the specified stroke time.

4.0

Immediate Corrective Actions

When the PORVs were determined to be inoperable, they were placed in the open position to provide a RCS vent path in compliance with Technical Specification 3.1.G.

5.0

Additional Corrective Actions

The air line and component sizes will be increased to provide suf-ficient flow to cycle open the PORVs within the required time period prior to the units returning to service.

6.0 Actions Taken to Prevent Recurrence No further action is considered necessary.

7.0

Similar Events

None.

8.0 Manuf acturer/!!odel Number N/A g,o.. u..

s PCO VIRGINIA ELECTRIC AND POWER COMPANY Surry Power Station P. O. Box 315 Surry, Virginia 23883 January 23, 1987 U.S. Fuclear Regulatory Commission Serial No:

86-061 Document Control Desk Docket No.:

50-280 016 Phillips Building License No: DPR-32 Washington, D.C.

20555 Gentlemen:

Pursuant to Surry Power Station Technical Specifications, Virginia Electric and Power Company hereby submits the following Licensee Event Report for Surry Unit 1.

REPORT NUMBER 87-001-00 This report has been reviewed by the Station Nuclear Safety and Operating Committee and will be reviewed by Safety Evaluation and Control.

Very truly yours, S

R. F. Saunders Station Manager Enclosure cc:

Dr. J. Nelson Grace Regional Administrator Suite 2900 101 Marietta Street, NW Atlanta, Georgia 30323

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