BVY 09-061, Response to Request for Additional Information on Generic Letter 2008-01
| ML093030485 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 10/22/2009 |
| From: | Michael Colomb Entergy Nuclear Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| BVY 09-061, GL-08-001 | |
| Download: ML093030485 (10) | |
Text
Entergy Nuclear Operations, Inc, Vermont Yankee P.O. Box 250 Enteigy Governor Hunt Road Vernon, VT 05354 Tel 802 257 7711 Michael J Colomb Site Vice President October 22, 2009 BVY 09-061 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001
SUBJECT:
GL 2008-01 Response to Request for Additional Information Vermont Yankee Nuclear Power Station Docket No. 50-271 License No. DPR-28
REFERENCES:
(a) NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," NVY 08-008, dated January 11, 2008 (b) Letter, Entergy to USNRC, "Vermont Yankee Three Month Response to Generic Letter 2008-01 ," BVY 08-020, dated April 10, 2008 (c), Letter, Entergy to USNRC, "Vermont Yankee Nine Month Response to Generic Letter 2008-01 ," BVY 08-071, dated October 14, 2008 (d) Letter, Entergy to USNRC, "Vermont Yankee Supplemental Response to Generic Letter 2008-01 ," BVY 09-002, dated January 28, 2009 (e) Letter, USNRC to Entergy, "Request for Additional Information (RAI) in Regard to the Vermont Yankee Responses to Generic Letter 2008-01 "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems" (TAC NO. MD7891), NVY 09-095, dated September 23, 2009
Dear Sir or Madam:
The Nuclear Regulatory Commission (NRC) issued Reference (a) to address the issue of gas accumulation in emergency core cooling, decay heat removal, and containment spray systems.
In References (b), (c) and (d), Entergy Nuclear Operations, Inc. (ENO) provided its schedule and response for the Vermont Yankee Nuclear Power Station. In Reference (e) the NRC provided a request for additional information (RAI). Attachment 1 to this letter provides ENOs response to the subject RAI. provides an update of the outstanding regulatory commitments.
If you have any questions or require additional information, please contact Mr. David Mannai at 802-451-3304.
BVY 09-61 / Page 2 of 2 I declare under the penalty of perjury that the foregoing information is true and correct.
Executed on October 22, 2009.
Sincerply,
[MJC/JMD]
Attachments: 1. Response to Request for Additional Information
- 2. Updated Regulatory Commitments cc: Mr. Samuel J. Collins, Regional Administrator U.S. Nuclear Regulatory Commission, Region 1 475 Allendale Road King of Prussia, PA 19406-1415 Mr. James S. Kim, Project Manager U.S. Nuclear Regulatory Commission Mail Stop O8C2A Washington, DC 20555 USNRC Resident Inspector Entergy Nuclear Vermont Yankee, LLC 320 Governor Hunt Road Vernon, Vermont 05354 Mr. David O'Brien, Commissioner VT Department of Public Service 112 State Street - Drawer 20 Montpelier, Vermont 05620-2601
BVY 09-61 Docket No. 50-271 Attachment 1 Vermont Yankee Nuclear Power Station Response to Request for Additional Information
BVY 09-61 / Attachment 1 / Page 1 of 5 GL 2008-01 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION RAI No. 1:
In Reference 4, Vermont Yankee states that the periodicity of venting of the High Pressure Coolant Injection (HPCI) suction and discharge piping and the Core Spray (CS) and Residual Heat Removal (RHR) suction piping will be established based on the results of venting operations. What venting operations will be done, and what criteria will determine the venting periodicity?
Response
In BVY 08-071, Entergy Nuclear Operations (ENO) committed to install a vent on the HPCI suction piping during Refueling Outage (RFO) 27 and to revise HPCI procedures to include periodic venting of the HPCI suction piping. A vent valve was installed in the HPCI Suction line during RFO 27 and the system was vented to ensure that there were no significant voids in the line at that time. Current procedures require periodic (monthly) venting of the suction piping when the level of the normal supply from the Condensate Storage Tank (CST) drops below 35% or when the system is aligned from the alternate supply from the Torus. This is consistent with Technical Specification Surveillance Requirement (SR) 4.5.1.3 for the venting of the HPCI discharge piping. Entergy is currently planning to institute administrative controls for gas monitoring using either periodic venting or ultrasonic (UT) examination when the system is aligned to the CST at all CST levels. The initial periodicity will be monthly. Changes to the initial monthly periodicity will be performance based (i.e., changes will be made following successful completion of a series of venting or UT operations).
In BVY 08-071, ENO committed to install vents on the HPýCI discharge piping. This piping was determined to be potentially vulnerable. However, actual UT measurements did not identify a void. Based on this, in lieu of adding additional vents, ENO plans to modify existing procedures to perform dynamic venting whenever this portion of the system is drained for maintenance. Performance based administrative controls will also be implemented to perform UT examinations as discussed above.
In BVY 08-071, ENO committed to install vents on the RHR and CS suction piping during RFO 28, scheduled for Spring 2010. Following installation of these vent valves, applicable procedures will be revised as required. Prior to installation of these vents performance based administrative controls will be implemented to perform venting or UT examinations as discussed above.
The administrative controls, as discussed above, are still under development at this time and will be completed on a schedule consistent with that provided in Attachment 2.
An update to the commitments made in BVY 08-071 is included with this letter.
BVY 09-61 / Attachment 1 / Page 2 of 5 RAI No. 2:
Do the Technical Specification Surveillance Requirements for venting include piping associated with all modes of RHR, specifically Shutdown Cooling, Suppression Pool Cooling, and Containment Spray Cooling? If not, what process will be used to determine if voids exist in this piping, and with what periodicity will this process be performed?
Response
The Technical Specifications (TS) define the venting requirements for venting RHR discharge piping. This is performed from the high point vent located on the Containment Spray Cooling (CSC) portion of the system. This would apply to the Shutdown Cooling (SDC), Suppression Pool Cooling (SPC) and CSC modes to the extent that these modes of RHR rely on this common discharge piping.
Venting the RHR during SDC is performed by flushing the supply and return path using the Condensate System prior to initiating SDC. Any voids are flushed and any air in the RHR piping is dynamically vented back to Radwaste prior to initiating SDC.
RHR Torus suction piping used for the SPC and CSC modes of RHR is discussed in the response to RAI No.l.
RAI No. 3:
The gas concern covers all conditions where operability is necessary to maintain safe operation. It is not limited to design basis accidents or maintaining safe shutdown. Therefore, address all conditions where operability is necessary to maintain safe operation. Note/this includes shutdown operation.
Response
TS define the operability requirements for all modes of operation. For the subject systems there are TS that require the systems to be operable during power operation and certain times when the reactor is shutdown. When the systems are required to be operable the systems would be expected to be capable of performing their design requirements. The TS establish SRs to ensure that systems can fulfill their design requirements. For example, TS SR 4.5.1.3 requires discharge piping to be filled with water and establishes monthly venting to provide reasonable assurance that this condition exists. When a system is removed from service for maintenance that could affect the filled condition it would be required to meet this SR prior to being declared operable.
BVY 09-61 / Attachment 1 / Page 3 of 5 Ensuring that the piping is full of water is either currently governed by the TS, or if not, would be handled under the 10CFR50 Appendix B program requirements to ensure design requirements are translated into procedures. As the result of performance based monitoring, station procedures will be updated, as required, to perform periodic monitoring to ensure piping remains water filled. If excessive air is detected while the system is required to be operable, entry into the Corrective Action Process (CAP) will be required. Existing procedures will be revised to capture monthly venting results, to trend results and enter into the corrective action program, if necessary.
RAI No. 4:
Describe the method(s) used to determine void volume. Will voids be sized prior to venting? If so, how will these data be recorded and tracked?
Response
The method used to determine void volume for the initial GL 2008-01 assessment was UT with a supporting calculation.
For future operations, voids will be either periodically sized using UT or vent locations will be screened for the presence of excessive voids. Venting will be performed through a controlled opening, for an established time, and accounts for other system parameters.
The screening criteria may be modified over time based on gaining additional insights from the monitoring program or based on industry and Entergy fleet efforts.
The procedure changes will require entry into the CAP if the initial screening criteria is exceeded to accommodate tracking and trending.
RAI No.5:
What testing is done after venting to verify gas was removed and to ensure gas was not transported into a high point that was previously found to be gas-free?
Response
Testing of the "A" and "B" RHR CSC loops is not required because the vents are at the highest location. CSC is open to the drywell atmosphere.
Testing of the RHR LPCI injection lines is not required because vents will be installed during RFO 28 to vent air between the normally closed and normally open injection valves. Any air in this location after venting will be located after the first closed valve between the reactor and will not create any concerns, such as a water hammer.
BVY 09-61 / Attachment 1 / Page 4 of 5 Testing of the CS injection lines is not required because UT testing of the high point (on one of two lines), located approximately 18" above the vents, was demonstrated by UT to be gas free. CS flow is injected to the vessel during each shutdown and any void in this location is dynamically vented into the reactor.
Testing of the HPCI CST Suction line is not required because the head from the CST maintains this line pressurized and the line slope does not create a location where a void can accumulate.
RAI No. 6:
What measures are in place to guard against inadvertent draining or incorrect maintenance procedures that could result in gas intrusion? What measures are in place to guard against gas intrusion during system realignments or other evolutions?
Response
During system restoration for those systems within the scope of the Generic Letter after maintenance activities or-an outage, the systems are filled and vented per procedure and pressurized to check for'leaks.
Inadvertent draining of a system is protected by the Operations tagging order. Incorrect maintenance procedures that could result in gas intrusion would not have an adverse impact. Any air introduced into a system as the result of incorrect maintenance procedures would occur within the tagging boundary that the maintenance is being performed. The system is filled and vented per procedure prior to declaring the system operable.
Air is not introduced into a system during system realignments. Realignment from system to system would not introduce air based on the systems being pressurized above atmospheric pressure and air would not be introduced into a higher pressure system.
RAI No. 7:
How do you control and revise work packages because of changes in maintenance work scope, including review and reauthorization of the packages and any new temporary procedures, to ensure that gas intrusion issues are considered?
Response
Changes in work packages for those systems within the scope of the Generic Letter are controlled by maintenance work scope changes. In the event the scope of work changes to include additional piping or valves, the tagging boundary changes accordingly. The modified tagging boundary is controlled by procedures.
BVY 09-61 / Attachment 1 / Page 5 of 5 A final step in a work package on a system that has been breached (drained and opened) is to restore the system in accordance with the tagging procedure. The tagging procedure restores the system and provides direction to fill and vent the system based on where it has been drained and the tagging boundary.
RAI No.8:
Training was not identified in the GL but is considered to be a necessary part of applying procedures and other activities when addressing the issues identified in the GL. Briefly discuss training.
Response
Operations training is performed as vents are added to the systems within the scope of the Generic Letter. The Operations training captures affected procedures, frequency of venting and vent location.
Engineering Support Personnel (ESP) Continuing Training was performed that covered the background, location of identified voids or potentially voided pipe, operability evaluation basis, affected procedures and future design considerations.
The need for additional training is under consideration through our training evaluation action request process.
BVY 09-61 Docket No. 50-271 Attachment 2 Vermont Yankee Nuclear Power Station Updated Regulatory Commitments
"4 1 .
BVY 09-061 Docket No. 50-271 Vermont Yankee Nuclear Power Station Response to Generic Letter 2008-01 List of Regulatory Commitments The following table identifies those actions committed to by Entergy in this document. Any other statements in this submittal are provided for information purposes and are not considered to be regulatory commitments.
TYPE SCHEDULED COMPLETION COMMITMENT (Check one) DATE ONE-TIME CONTINUING ACTION COMPLIANCE Revise applicable HPCI procedure(s) to X January 2010 require dynamic venting of HPCI discharge piping following any maintenance activities that could drain the system.
Install vents on CS suction piping, RHR REQ 28 suction piping and RHR LPCI injection piping and revise applicable procedures to include periodic venting or UT.
Revise existing procedures to capture the X January 2010 results of venting operations, on HPCI, CS and RHR systems.
Implement performance based X January 2010 administrative controls to UT or vent HPCI, RHR and CS suction piping and CS discharge piping.
Submit, to the NRC, proposed changes to X Within 90 days the VY TS based on the final, approved following NRC version of the Technical Specifications publication of Task Force (TSTF) Traveler for the Notice of unacceptable gas accumulation in ECCS Approval of the systems, adjusted as needed to account TSTF Traveler for plant-specific VY design and licensing in the Federal basis. Register