ML15072A112

Special Report - Seismic Monitoring Instrumentation Inoperability, Revision 1

ML15072A112
Person / Time
Site:	Limerick
Issue date:	03/13/2015
From:	Dougherty T Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LG-15-039, TRM 3.3.7.2
Download: ML15072A112 (3)

Text

LG-15-039 TRM 3.3.7.2 March 13, 2015 U.S. Nuclear Regulatory Commission Attn.: Document Control Desk Washington, DC 20555-0001 Limerick Generating Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-39 and NPF-85 NRC Docket Nos. 50-352 and 50-353

Subject:

Special Report - Seismic Monitoring Instrumentation Inoperability, Revision 1

Reference:

Special Report - Seismic Monitoring Instrumentation Inoperability, Revision 0, dated December 5, 2014 This Special Report is being updated and re-submitted pursuant to the requirements of Limerick Generating Station (LGS), Unit 1 and Unit 2 Updated Final Safety Analysis Report (UFSAR) section 3.7.4.5, Technical Specification 6.9.2, and Technical Requirements Manual 3.3.7.2 that states, With one or more of the seismic monitoring instruments inoperable for more than 30 days, a Special Report shall be prepared and submitted to the Nuclear Regulatory Commission pursuant to Specification 6.9.2 of the Technical Specifications within the next ten days outlining the cause of the malfunction and the plans for restoring the instrument(s) to operable status. This revised report includes the identification of one additional degraded channel.

On Sunday, October 26, 2014, Unit 1 and Unit 2 were operating at 100% power with functional testing (ST-2-036-600-0) of seismic monitoring instrumentation in progress. During the test, at approximately 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br />, the seismic monitor sensor array (XE-VA-105) for the D Main Steam Line (MSL) did not respond as expected and was declared inoperable.

On Tuesday, February 3, 2015, Unit 1 was operating at 100% power and Unit 2 was operating at approximately 99.8% power with functional testing (ST-2-036-606-0) of the Spray Pond Pump House (SPPH) seismic monitoring instrumentation in progress. During the test, at approximately 0926 hours0.0107 days <br />0.257 hours <br />0.00153 weeks <br />3.52343e-4 months <br />, the SPPH seismic monitor sensor array (XRSH-VA-107) for the SPPH foundation did not respond as expected and was declared inoperable.

Each sensor array has three channels which measure longitudinal movement, vertical movement, and transverse movement. For the MSL channel, the sensor array did not exhibit the correct waveforms during the functional test. Instrumentation and Control (I&C) and Engineering personnel determined that the D MSL sensor array was degraded. The sensor array is located in the Unit 1 drywell and cannot be accessed for recalibration or repair without a plant outage.

LG-15-039 March 13, 2015 Page 2 The SPPH foundation channel sensor did not respond properly during testing. The cause of the failure is unknown. The current sensor cannot be repaired since it is obsolete and replacement parts are not available. A different model replacement sensor is being procured with a lead time of 60 days. This will be followed by Engineering evaluation, planning, and installation which is estimated to result in a return to operable status in approximately 5 months.

Four of six system instrument sensors remain operable. The inoperable seismic monitor sensor array (XE-VA-105) that is located in the drywell of Unit 1 will be repaired, tested, and returned to operable status by the end of the 1R16 refueling outage (April 2016). The inoperable SPPH foundation sensor (XRSH-VA-107) will be restored to operable by July 31, 2015.

There are two regulatory commitments identified in this letter. The commitments are listed in .

If you have any questions, please contact Robert B. Dickinson at (610) 718-3400.

Sincerely, Original signed by David P. Lewis for Thomas J. Dougherty Vice President - Limerick Generating Station Exelon Generation Company, LLC

Attachment:

List of commitments cc: Administrator, Region I, NRC NRC Senior Resident Inspector, Limerick

LG-15-039 March 13, 2015 Page 3 ATTACHMENT 1

SUMMARY

OF REGULATORY COMMITMENTS The following table identifies commitments made in this document. (Any other actions discussed in the submittal represent intended or planned actions. They are described to the NRC for the NRC's information and are not regulatory commitments.)

COMMITTED COMMITMENT TYPE COMMITMENT DATE OR "OUTAGE" ONE-TIME PROGRAMMATIC ACTION (Yes/No)

(Yes/No)

The inoperable seismic monitor Outage Yes No sensor array (XE-VA-105) that is located in the drywell of Unit 1 will be repaired, tested, and returned to operable status by the end of the 1R16 refueling outage (April 2016).

The inoperable SPPH 7/31/2015 Yes No foundation sensor (XRSH-VA-107) will be restored to operable status by July 31, 2015.