ML13045A482
| ML13045A482 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 01/31/2013 |
| From: | Price J Dominion Nuclear Connecticut |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 13-062 | |
| Download: ML13045A482 (6) | |
Text
Dominion Nuclear Connecticut, Inc.
Millstone Power Station JAN 312013 Ž,Dominion Rope Ferry Road Waterford, CT 06385 U.S. Nuclear Regulatory Commission Serial No.13-062 Attention: Document Control Desk NLOS/WDC RO Washington, DC 20555 Docket No. 50-336 License No. DPR-65 DOMINION NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNIT 2 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSE AMENDMENT REQUEST TO REVISE SR 4.4.3.2, RCS RELIEF VALVES By letter dated December 17, 2012, Dominion Nuclear Connecticut, Inc. (DNC) submitted a license amendment request (LAR) to revise Technical Specification (TS) 3/4.4.3, Reactor Coolant System Relief Valves, for Millstone Power Station Unit 2 (MPS2). The proposed amendment would revise Surveillance Requirement (SR) 4.4.3.2 to remove the requirement to perform the quarterly surveillance for a pressurizer power-operated relief valve (PORV) block valve that is being maintained closed in accordance with TS 3.4.3 Action a. By email dated January 22, 2013, the Nuclear Regulatory Commission (NRC) transmitted a request for additional information (RAI) related to the LAR. DNC agreed to respond to the RAI by February 5, 2013.
Attachment 1 provides DNC's response to the NRC's RAIs.
If you have any questions regarding this submittal, please contact Wanda Craft at (804) 273-4687.
Sincerely, J. AePrice an Vice President - Nuclear Engineering STATE OF CONNECTICUT )
COUNTY OF NEW LONDON )
The foregoing document was acknowledged before me, in and for the County and State aforesaid, today by J. Alan Price, who is Vice President - Nuclear Engineering of Dominion Nuclear Connecticut, Inc. He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that company, and that the statements in the document are true to the best of his knowledge and belief.
Acknowledged before me this- / s"" day of , 2013. /' 4 MV Commission Expires: ("L6Th'1 2' 7-, /-
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- . -,', S C .AR xL Notary Public NOTARY PUBLIC MY COMMISSION EXPIRES FEBRUARY 28, 2016
Serial No.13-062 Docket No. DPR-65 Page 2 of 2
Attachment:
- 1. Response to Request for Additional Information Regarding License Amendment Request to Revise SR 4.4.3.2, RCS Relief Valves Commitments made in this letter: None cc: U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd.
Suite 100 King of Prussia, PA 19406-2713 J. S. Kim Project Manager - Millstone Power Station U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 08 C2A Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station
Serial No.13-062 Docket No. 50-336 ATTACHMENT 1 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGAIRDING LICENSE AMENDMENT REQUEST TO REVISE SR 4.4.3.2. RCS RELIEF"VALVES MILLSTONE POWER STATION UNIT 2 DOMINION NUCLEAR CONNECTICUT, INC.
Serial No.13-062 Docket No. 50-336 Attachment 1, Page 1 of 3 By letter dated December 17, 2012, Dominion Nuclear Connecticut, Inc. (DNC) submitted a license amendment request (LAR) to revise Technical Specification (TS) 3/4.4.3, Reactor Coolant System Relief Valves, for Millstone Power Station Unit 2 (MPS2). The proposed amendment would revise Surveillance Requirement (SR) 4.4.3.2 to remove the requirement to perform the quarterly surveillance for a pressurizer power-operated relief valve (PORV) block valve that is being maintained closed in accordance with TS 3.4.3 Action a. By email dated January 22, 2013, the Nuclear Regulatory Commission (NRC) transmitted a request for additional information (RAI) related to the LAR. This attachment provides DNC's response to NRC's RAIs.
RAI 1
What was the originalbasis for the surveillance requirement in its current state?
DNC Response TS 3/4.4.3, RCS Relief Valves, did not exist in the MPS2 TSs when they were originally issued for commercial operation in August 1975. The TS, and its associated surveillance requirements, were added to the MPS2 TSs under License Amendment (LA) 66 in direct response to lessons learned from the Three Mile Island accident. LA 66 was approved by the NRC on April 1, 1981.
Since its original form in April 1981, surveillance requirement 4.4.3.2 has been modified by the following LAs:
" LA 68, which was approved by the NRC on May 6, 1981, revised surveillance requirement 4.4.3.2 to exclude cycling of a PORV block valve if it was. closed (and power removed) to meet Specification 3.4.3 Actions a or b.
" LA 185, which was approved by the NRC on February 15, 1995, revised TS 3.4.3 to add an action statement to allow the manual cycling of the PORV in the case where the valve has been declared inoperable but can still be closed and therefore continue to perform the intended safety function. As a result of this change, surveillance requirement 4.4.3.2 was revised to exclude cycling of a PORV block valve if it was closed (and power removed) to meet Specification 3.4.3 Actions b or c, which are the revised Action numbers as a result of the addition of the new Action.
RAI 2
Are there any circumstances where manual operation of an inoperable PORV would be prevented, although required, due to a closed block? If yes, is there a circumstance where this could have been prevented if the surveillance was unchanged?
Serial No.13-062 Docket No. 50-336 Attachment 1, Page 2 of 3 DNC Response No, there are no circumstances where required manual operation of an inoperable PORV would be prevented due to a closed block valve. The existing TS surveillance for the block valve is exempted if following TS 3.4.3 action "b" or "c" in which the block valve is closed and power is removed from the valve operator. The requested change would also exempt the block valve from the required surveillance when complying with TS 3.4.3 action "a". Under this action, the PORV is inoperable but capable of being manually operated remotely from the control room and power is maintained to the block valve actuator. Manual operation of the PORV and block valve is executed, as needed, from the control room by operation of the control switches to open and close both the block valve and the PORV.
RAI 3
The FSAR states that the PORVs are used for low temperature overpressureprotection.
Does the change in the surveillance requirement impact low temperature overpressure protection? If so, what is the impact?
DNC Response No, the proposed change to TS surveillance requirement 4.4.3.2 does not impact low temperature overpressure protection (LTOP). In accordance with TS 3.4.9.3, LTOP is required in Modes 4, 5 and 6. Surveillance requirement 4.4.3.2 is only applicable in Modes 1, 2, and 3. Provided that the condition which caused the PORV to originally be considered inoperable (e.g., seat leakage) does not prevent its LTOP function, the block valve can be opened to allow use of the PORV for the LTOP function. With the RCS at a lower pressure and temperature, the risk of a small break LOCA from a potentially stuck open PORV is considered to be significantly diminished.
RAI 4
Have indicationsof leakage through the PORV been detected in the containment? If so, has the leakage been identified as liquid or gaseous?
DNC Response No, leakage through the PORV has not been detected in containment. The PORV leakage is internal to the valve and is believed to be seat leakage (pilot disk, main disk, or a combination of both). The leakage exits the valve and pressurizer as steam through a tail piece pipe and is captured and condensed in the quench tank. The quench tank is an enclosed tank inside containment which is vented, as needed, to the gaseous waste
Serial No.13-062 Docket No. 50-336 Attachment 1, Page 3 of 3 processing system. Liquid captured in the quench tank is considered part of RCS identified leakage and is drained, as needed, to the primary drain tank which is in turn is drained to the clean liquid waste processing system.
RAI 5
Has the cause of the PORV leakage been determined? Are there plans to correct, prevent, and mitigate the leakage in all PORVs?
DNC Response No, the cause of the PORV leakage has not yet been determined. During the next MPS2 refueling outage, currently scheduled for the spring 2014 (2R22), the valve will be overhauled to determine the cause and correct the leakage. The cause of the PORV leakage will be documented in the Millstone Power Station Corrective Action Program including further corrective actions, as required, to address any generic applicability to the other PORV.