05000306/LER-2005-001

LER-2005-001,

Docket Number
Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v)(C), Loss of Safety Function - Release of Radioactive Material
3062005001R00 - NRC Website

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3) 05 -- 01 — 0

EVENT DESCRIPTION

On March 28, 2005 a Corrective Action Process (CAP) item identified potential non-code repairs had been made to 21, 22, and 23 Containment Fan Coil Unitsl(CFCUs) since January 2005. The repair performed was an overlay described as filling a pinhole leak with brazing material in the copper tubing of the CFCU. This repair may not have removed the flaw and was not done in accordance with a code approved weld repair procedure. The initial operability evaluation concluded that the CFCUs remained operable.

Further evaluation, in the form of an Operability Recommendation performed by Engineering examined the qualifications of the repair techniques utilized on previous Unit 2 CFCU leakage events and concluded on March 30 that while the structural integrity could be assured the repair constituted a non-code repair. The CFCU tubes are American Society of Mechanical Engineers (ASME) Code Class 2. Temporary non-code repairs are not acceptable, per Nuclear Regulatory Commission (NRC) Generic Letter 90-05, without prior NRC approval. This conclusion resulted in 3 of the 4 CFCUs, being declared inoperable and required Unit 2 to be shutdown per Technical Specifications (TS) until code repairs were completed.

Code repair of the 21, 22, and 23 CFCUs were completed on April 3, 2005.

EVENT ANALYSIS

The containment cooling system2 is a closed system in containment. There are two trains with two CFCUs per train. Integrity of the tubes in the CFCUs is required for containment integrity. The CFCU tubes support two safety functions: (1) circulating cooling water for containment cooling in the event of a loss of coolant accident (LOCA) or main steam line break in containment, and (2) serving as a containment boundary during the first hours of a LOCA when containment pressure will exceed the pressure of the cooling water in the CFCUs.

TS 3.6.5, Containment Spray and Cooling Systems, allows one train of containment cooling to be inoperable. TS 3.6.1, Containment, requires that containment be operable. Containment and both shutdown was completed per TS 3.0.3 (since TS 3.6.5 does not have a condition for two trains of containment cooling inoperable) and TS 3.6.1. Thus, this shutdown is reportable per 10 CFR 50.73(a)(2)(i)(B)

• 1 (EIIS Component Identifier: FCU) 2 (EIIS System Identifier: BK) FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6 PAGE (3) 05�01 0 Impact on Safety System Functional Failure Performance Indicator The CFCUs contain an air-to-water heat exchanger supplied with water from the cooling water system in order to remove containment heat. In this event, three of the CFCUs were determined to be inoperable due to non-code repairs of pinhole leaks that had not received prior approval from the NRC. There was no active leak at the time this condition was discovered and an engineering assessment concluded that structural integrity of the CFCUs was not lost. Therefore, this event did not result in loss of any safety function, thus,-this event is not reportable per 10 CFR 50.73(a)(2)(v)(C) as a Unit 2 Safety System Functional Failure (SSFF).

SAFETY SIGNIFICANCE

There were no active leaks occurring when this condition was discovered and the engineering assessment concluded that the non-code repairs would have maintained structural integrity. Based on this assessment, the health and safety of the public was not affected.

CAUSE

Nuclear Management Company, LLC, (NMC) conducted a root cause evaluation of this condition.

The root cause evaluation determined planners and technical reviewers lack of understanding led to the selection of a brazing procedure that was not qualified for the joint configuration that was used.

CORRECTIVE ACTION

Immediate:

1. Unit 2 was shutdown per Technical Specification 3.0.3.

Subsequent:

2. 21, 22, and 23 CFCUs were repaired per the ASME Code and returned to service. As noted in Licensee Event Report 2-04-01, Supplement 1, Unit 2 CFCU cooling coils have been replaced since this event occurred.

Planned:

3. The Root Cause Evaluation recommended a number of training actions to correct limitations of the knowledge of site personnel who would be involved in any potential future repairs.

FACILITY NAME (1)I:/.

• DOCKET NUMBER (2) LER NUMBER (6 PAGE (3) 05 -- 01 -- 0

PREVIOUS SIMILAR EVENTS

Licensee Event Report 2-04-01 was submitted pursuant to 10 CFR 50.73(a)(2)(i)(B) for a Technical Specification required shutdown that was a result of CFCU leaks.