NOC-AE-03001521, Facsimile Letter, Commitment to Investigate and Repair Bottom Mounted Instrumentation Penetration Indications

Facsimile Letter, Commitment to Investigate and Repair Bottom Mounted Instrumentation Penetration Indications

ML031410712
Person / Time
Site:	South Texas
Issue date:	04/24/2003
From:	Sheppard J South Texas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
Thadani M, NRR/DLPM, 415-1476
References
NOC-AE-03001521
Download: ML031410712 (2)

Text

.PR24-200316:22 STPEGS 361 972 8298 P. 02/16 Nuclear Operating Company South /.f Mt/ vr1h., ro

.Z=77Z4V m0tEsatk.71tJ April 24,2003 NOC-AE-03001 521 IOCFR50 U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852 South Texas Project Units 1 & 2 Docket Nos. STN 50-498, STN 50-499 Commitnent to Investigate and Repair Bottom Mounted Instrumentation Penetration Indications On Apil 12, 2003, STP Unit 1 was in cold shutdown and making preparations to restart from its eleventh refueling outage (IREI 1). While performing a routine inspection of the reactor coolant system (RCS) and associated systems as part of the STP boric acid control program, a system engineer found what appeared to be very small amounts of boric acid residue on two bottom mounted instrumentation (1MI) penetrations on the reactor pressure vessel. ST? immediately began an aggressive effort to determine the origin of the residue, including radio-isotopic and chemical analyses using both on-site and off-site resources. STP apprised the NRC Resident Inspector of the condition. On April 13, 2003, ST? formally notified the NRC in accordance with I OCFR50.72, of the potential for RCS pressure boundary leakage.

The investigation results thus far indicate primary reactor coolant as the likely source of the residue.

STP is continuing to aggressively investigate the condition to detemine the root cause, identify non-destructive examination (NDE) methods, and evaluate repair options.

SI? believes the early detection of the BMI indications demonstrates the effectiveness of the visual inspections performed in the ST? boric acid control program.

On April 17, 2003, ST? and the NRC held a conference call in which STP briefed the NRC about the status of the invesfigation and STP's plans for fiuther action. As discussed during that call, ST?

is committed to an effort that includes the following elements: 1) investigation of the root cause, 2) determination of the extent of the condition, 3) identification and implementation of effective conective actions, and 4) briefing the NRC prior to restarting the unit. The details of these elements are described more fully below.

03001S21 BMI CommitmenLdoc STI: 3159S260

-.. .- . N-24-200I3 c vnn ------

361 972 8298 P .03/16 Page 2

1. Root Cause: STP will investigate the condition using adequate inspection and non-destructive examination techniques, including metallographic analysis, as necessary to determine the most likely cause of the apparent reactor coolant leak. At a minimum, techniques will include qualified visual inspections in combination with eddy current testing and/or ultrasonic testing.

STP expects to continue to use industry experts in addition to its own highly qualified and experienced staff to validate the root cause determination.

2. Extent of Condition: STP will evaluate the information from the investigation and determiine the likely effect on the other BMI penetrations, including those in Unit 2. STP will also apply available NDE to detemine if there has been any wastage associated with the condition.

3. Effective Corrective Action: STP will repair the conditions that caused the residue and assure that the pressure boundary integrity is in accordance with the ASME Code as required by IOCFRSO.55a. STP will irnplement additional corrective actions, as required, to address the long-term management of potential BMI Alloy 600 issues.

4. NRC Briefing: STP will meet wit the NRC to review the results of the investigaion of the root cause, evaluation of extent of condition and corrective action prior to restarting the unit.

STP also recognizes the importance of keeping the NRC informed about progress on the investigation and resolution of the condition, and will support conference calls and meetings with tie staff, and provide supporting technical information as needed. Comnitments made by STP in the resolution of this issue will be documented by submittals on the ST? docket.

Please call me at (361) 972-8757 or Gary Parkey at (361) 972-7800 if you have any questions about these commitnents.

J. J. Sheppard President and Chief Executive Officer awh