RS-10-054, Clarification to Response to Request for Additional Information Regarding the One-Time Extension of the Essential Service Water Train Completion Time
| ML100780401 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 03/19/2010 |
| From: | Simpson P Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RS-10-054 | |
| Download: ML100780401 (3) | |
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Exelon Nuclear www.exeloncorp.com 4
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Winfield Road Nuclear Warrenville, lL 60555 RS-1 0-054 March 19, 2010 10 CFR 50.90 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Byron Station, Units 1 and 2 Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN 50-455
Subject:
Clarification to Response to Request for Additional Information Regarding the One-Time Extension of the Essential Service Water Train Completion Time
Reference:
Letter from P. R. Simpson (Exelon Generation Company, LLC) to U. S.
Nuclear Regulatory Commission, "Response to Request for Additional lnformation Regarding the One-Time Extension of the Essential Service Water Train Completion Time," dated March 9, 2010 In the Referenced letter, Exelon Generation Company, LLC, (EGC) provided a response to an NRC request for additional information regarding the license amendment for Byron Station, Units 1 and 2, to revise Technical Specifications (TS) Limiting Condition for Operation (LCO) 3.7.8, "Essential Service Water (SX) System," to extend the Completion Time (CT) from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 144 hours0.00167 days <br />0.04 hours <br />2.380952e-4 weeks <br />5.4792e-5 months <br />. Identified in the response to Question 1.2 were scenarios that could potentially divert flow from the SX system during an accident. One scenario provided in the response concerned the impact of backwashing of SX strainers on SX cooled components.
An NRC inspector stated a concern with a statement in the response to Question 1.2.
Specifically, the statement giving rise to the NRC concern in the Referenced letter is as follows:
During normal plant operations the SX strainer aligned to the operating SX pumps are back washed pro-actively on a routine basis to prevent any significant debris buildup.
Therefore, EGC is clarifying the statement.
Multiple actions are taken at Byron Station with respect to the SX strainers:
- 1) Monitoring of the SX strainer differential pressure (dp) during shiftly equipment operator rounds (two readings per day). For the operator rounds, an SX strainer dp reading greater than 8 psid is out of specification, and the equipment operator is instructed to notify supervision. Effective March 12, 201 0, the operator rounds were revised as part of margin management to require the SX strainer to be backwashed for an SX strainer dp reading greater than or equal to 5.5 psid.
March 19,201 0 U. S. Nuclear Regulatory Commission Page 2
- 2) Monitoring of SX strainer dp via an alarm function in the Control Room. In accordance with Byron alarm response procedures BAR 1-2-C2 and BAR 2-2-C2, an SX strainer dp reading of 9 psid will result in an alarm in the Control Room. The immediate operator action in response to the alarm is to manually backwash the affected SX strainer in accordance with operating procedure BOP SX-4, "Essential Service Water Strainer Manual Operation."
- 3) Surveillance test procedures OBOSR 7.9.6-1 and OBOSR 7.9.6-2, "Essential Service Water Makeup Pump OA [OBI Monthly Operability Surveillance," test the SX makeup pumps on a monthly basis. As part of performing the tests, the applicable SX basin level is lowered. One of the methods the test procedures state can be used to lower an SX basin's level is the backwash of an SX strainer. Of the 26 times the tests were conducted between December 2008 and December 2009, the option to backwash an SX strainer was used 12 out of 26 times.
EGC considers the monitoring of the SX strainer dp readings and backwashes described above effective at preventing any significant debris buildup and supporting the conclusion provided in the response to Question 1.2.
EGC has reviewed the information supporting a finding of no significant hazards consideration that was previously provided to the NRC in the EGC license amendment request dated September 24, 2009. The additional information provided in this submittal does not affect the bases for concluding that the proposed license amendment does not involve a significant hazards consideration.
In accordance with 10 CFR 50.91, "Notice for public comment; State consultation," paragraph (b),
a copy of this letter and attachment are being provided to the designated State of Illinois official.
There are no regulatory commitments contained in this letter.
Should you have any questions concerning this letter, please contact Ms. Lisa A. Schofield at (630) 657-281 5.
I declare under penalty of perjury that the foregoing is true and correct. Executed on the 19th day of March 201 0.
Respectfully, Patrick R. Simpson Manager - Licensing C/
Exelon Generation Company, LLC
March 19,2010 U. S. Nuclear Regulatory Commission Page 3 cc:
NRC Regional Administrator, Region Ill NRC Senior Resident Inspector, Byron Station NRR Project Manager, Byron Station Illinois Emergency Management Agency - Division of Nuclear Safety