05000315/LER-2004-001

LER-2004-001, Failure To Comply With Technical Specification 3 .7 .5 .1, Control Room Emergency Ventilation System

Docket Number
Event date:	07-19-2003
Report date:	06-28-2004
3152004001R00 - NRC Website

• Donald C. Cook Nuclear Plant Unit 1 05000-315 17. TEXT (If more space is required, use additional copies of NRC Form (366A) Conditions Prior to Event Unit 1 = 100% power Unit 2 = 100% power

Description of Event

This Licensee Event Report reports an historical failure to comply with Unit 1 and 2 Technical Specification (TS) 3.7.5.1, Control -Room Emergency Ventilation System (CREV)(AHU). The noncompliance was identified in 2004 during troubleshooting to identify the cause for a very slow loss of volume from the refueling water storage tank (RWST).

On June 24, 2003, Indian Michigan Power Company (I&M) detected a small leak from the pressure seal ring of valve 2-SI-206, south SI pump discharge valve manual isolation.

Upon discovery of this leak, I&M immediately evaluated the identified condition and determined that the increased leakage did not impact the operability of the

• SI system. The leakage from Valve 2-SI-206 was entered into I&M's corrective action program. _Further, I&M evaluated identified leakage from all known sources (including the leakage from 2-SI-206) and determined the aggregate leakage did not impact the operability of the CREV.

At 1337 hours0.0155 days <br />0.371 hours <br />0.00221 weeks <br />5.087285e-4 months <br /> on July 18, 2003, it was determined that the leak rate through the seal ring of 2-SI-206 had increased. Following discovery of this increased leak rate, I&M re-evaluated the effects the new aggregate leakage had on the SI and CREV systems.

This re-evaluation determined the SI and CREV systems were operable, but the leak rate had reached a rate where conservative operating practices required prompt actions be taken to resolve the concern.

At 0820 hours0.00949 days <br />0.228 hours <br />0.00136 weeks <br />3.1201e-4 months <br /> on July 21, 2003, the Unit 2 south SI system was removed from service to facilitate repair of valve 2-SI-206.

In March 2004, I&M identified a slow decrease of volume from the Unit 2 RWST. Due to the relatively small size of the leak from the RWST, the large volume within the RWST, and the sensitivity of level instrumentation associated with the RWST, the loss of volume from the RWST only became apparent via long-term trending of the tank's volume. In May 2004, I&M determined the source of the leak was leakage past the drain valves for the Unit 2 south SI pump. The evaluation determined that this previously unidentified leak existed during the time period when valve 2-SI-206 had its highest known leak rate (1337 hours0.0155 days <br />0.371 hours <br />0.00221 weeks <br />5.087285e-4 months <br /> on July 18, 2003, through 0820 hours0.00949 days <br />0.228 hours <br />0.00136 weeks <br />3.1201e-4 months <br /> on July 21, 2003). Actions were implemented to correct the leak through the drain valves for the Unit 2 south SI pump.

Donald C. Cook Nuclear Plant Unit 1 05000-315 17. TEXT (If more space is required, use additional copies of NRC Form (366A) On May 4, 2004, Indiana Michigan Power Company (I&M) determined that the combined leakage from valve 2-SI-206, south safety injection (SI) [BJ] pump discharge valve manual isolation pressure seal ring, and seat leakage past the drain valves for the Unit 2 south SI pump casing was greater than that assumed in the safety analysis for Unit 1 and 2 TS 3.7.5.1, Control Room Emergency Ventilation System. This condition existed for 66 hours7.638889e-4 days <br />0.0183 hours <br />1.09127e-4 weeks <br />2.5113e-5 months <br /> and 43 minutes during the period of 1337 hours0.0155 days <br />0.371 hours <br />0.00221 weeks <br />5.087285e-4 months <br /> on July 18, 2003, through 0820 hours0.00949 days <br />0.228 hours <br />0.00136 weeks <br />3.1201e-4 months <br /> on July 21, 2003.

Technical Specification 3.7.5.1, Action b requires with the filter unit inoperable; restore the filter unit to OPERABLE status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

Contrary to this requirement, the filter units for-Unit 1 and 2 were inoperable for a period of 66 hours7.638889e-4 days <br />0.0183 hours <br />1.09127e-4 weeks <br />2.5113e-5 months <br /> and 43 minutes.

Cause of Event

The cause of I&M's non-compliance with Unit 1 and 2 TS 3.7.5.1.was the aggregate SI pump casing-drain valves was greater than that assumed in the accident analysis for Unit 1 and 2 TS 3.7.5.1, Control Room Emergency Ventilation System.

Analysis of Event

Analysis of the leaks determined that the leak rate did not impact the operability of the ECCS. The volume of liquid remains adequate to support long-term cooling using containment sump recirculation following a loss of coolant accident (LOCA). The- combined leakage exceeded the leak rate assumed in the post-LOCA control room radiological dose analysis. ECCS leakage in excess of the leak rate assumed in the analysis increases the dose consequences to greater than the GDC 19 (10 CFR 50.67) limit for control room habitability. The leakage did not exceed the leak rate used in the offsite dose analysis demonstrating compliance with the limits of 10 CFR 100.

Corrective Actions

Repaired Valve 2-SI-206, south SI pump discharge valve manual isolation. (JO 03167019) Repaired the drain valves for the Unit 2 south SI pump. (JO 04075005) Conducted maintenance monitoring of RWST volume to ensure the source of the leakage was identified and corrected. This post-maintenance monitoring demonstrated the source of the RWST leakage had, been adequately identified and corrected.

Previous Similar Events

None.