05000388/LER-2001-003

LER-2001-003,

Docket Number
Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded
3882001003R00 - NRC Website

EVENT DESCRIPTION

On March 19, 2001, at 0803 hours0.00929 days <br />0.223 hours <br />0.00133 weeks <br />3.055415e-4 months <br />, with Unit 2 in Condition 5 (Refueling) at 0 percent power, it was determined that the as-found minimum pathway Secondary Containment Bypass Leakage (SCBL) Technical Specification limit had been exceeded during regularly scheduled Local Leakage Rate Testing.

The Technical Specification SCBL limit is 9 scfh and the measured leakage was 9.14 SCFH. At that time, additional SCBL pathways remained to be leak rate tested. After completion of all leak rate testing, the total SCBL was determined to be 11.13 scfh. The major contributor to the SCBL was the RHR (EIIS Code: BO) Loop B Drywell Spray outboard isolation valve (EIIS Code: BD) with approximately 73% of the total minimum pathway SCBL leakage.

CAUSE OF EVENT

The cause of the high leakage through the RHR Loop B Drywell Spray outboard isolation valve (HV251F016B) was due to the gland follower and stem being in contact. During valve movement, the gland follower and the stem were rubbing against each other. This rubbing caused increased friction, which reduced the force that would normally be applied to the valve disc to seat interface. In addition, a small area of pitting on the disc contributed to the high leakage.

There are no generic implications due to this failure. The high leakage experienced on HV251F016B has not been experienced on the other similar valves. In addition, the RHR Loop A Drywell Spray outboard isolation valve (HV251F016A) was repacked during this outage with no evidence of stem and gland follower contact.

REPORTABILITY/SAFETY SIGNIFICANCE

This event was determined to be reportable in accordance with 10CFR50.73(a)(2)(ii) in that the total as- found minimum pathway leakage rate exceeded the Technical Specification limit. If a Design Basis Accident-Loss of Coolant (DBA-LOCA) with fuel failure had occurred in Unit 2, the leakage of 11.13 scfh (8.13 scfh from the RHR Loop B Drywell Spray penetration) would have bypassed secondary containment. This would have resulted in an increase in offsite dose. However, the increase in dose would not have exceeded either 10CFR100 or 10CFR50, Appendix A, GDC 19 dose limits. Therefore, there were no safety consequences or compromise to the public health or safety as a result of the increased Secondary Containment Bypass Leakage.

In accordance with the guidelines provided in NUREG-1022, Revision 2, Section 5.1.1, the required submission date for this report was determined to be May 18, 2001.

CORRECTIVE ACTION

The following corrective actions were completed on the RHR Loop B Drywell Spray outboard isolation valve:

• The gland follower was lined.

• The stem was replaced.

• The disc and seat were cleaned.

• The valve was satisfactorily retested.

ADDITIONAL INFORMATION

Failed Component: � 12 inch globe valve: HV251F016B Manufacturer: � Anchor Darling Valve Co.