ML062840126
| ML062840126 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 10/10/2006 |
| From: | Cowan P Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML062840126 (4) | |
Text
Exelon Nuclear www.exelonco~p.co~
200 Exelon ~ a y Kennett Square, PA 19348 I 0 CFR 50.55a October 10, 2006 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Limerick Generating Station, Units 1 and 2 Facility Operating License Nos. NPF-39 and NPF-85 NRC Docket Nos. 50-352 and 50-353
Subject:
Proposed Alternative Associated with the Second Ten-Year Interval inservice Testing (IST) Program - Relief Request No. 51-VRR-3 In accordance with 10 CFR 50 55a, Codes and standards, paragraph (a)(3)(i), Exelon Generation Company, LLC (EGC), is requesting relief from the American Society of Mechanica~
Engineers (ASME) OM Code, 1990 Edition, Code for Operation and Maintenance of Nuclear Power Plants, on the basis that the proposed alternative provides an acceptable level of quality and safety. Specifically, attached for your review and approval is a proposed alternative for Limerick Generating Station (LGS), Units 1 and 2, that will permit testing (i.e., disassembly, inspection, and partial flow testing) of Residual Heat Removal (RHR) System check valves during any plant mode.
Your approval is requested by October 10, 2007.
If you have any questions, please contact Thomas R. Loomis (610) 765-5510.
Very truly yours, Director, Licensing and Regulatory Affairs
Attachment:
I ) Relief Request No. 51-VRR-3 cc: S. J. Collins, Regional Administrator, Region I, USNRC S. Hansell, USNRC Senior Resident Inspector, LGS R. Guzman, Project Manager [LGS] USNRC J. Kim, Project Manager [LGS] USNRC
LGS, Units 1 and 2 Relief Request No. 51-VRR-3 Attachment 1 Page 1 of 3 RELIEF REQUEST NO. 51-VRR-3 1 ASME Code Components Affected:
Category: C - self actuating Valves: 51-1F046A, 51-2F046A 51-1F046B, 51-2F046B 51-1F046C, 51-2F046C 51-1F046D, 51-2FO46D System: Residual Heat Removal (RHR) System Valve Function: These check valves open to pass sufficient flow to protect the RHR pumps from overheating when operating in low flow or shutoff head conditions. The valves provide a recirculation flow path to the Suppression Pool prior to establishing a flow path to the Reactor Vessel.
2. Applicable Code Edition and Addenda
The Limerick Generating Station (LGS), Units 1 and 2, Inservice Testing Program for the second interval complies with the ASME-OM Code 1990 Edition. The second interval commenced on January 8,2000 and will conclude on January 7,2010.
3. Applicable Code Requirement
ASME OM Code-I 990, ISTC 4.5.4(c), Valve Obturator ~ovement,and Generic Letter 89-04, Guidance on Developing Acceptable in-service Testing Programs, Attachment 1, Position 2, Alternative to Full Flow Testing of Check Valves, paragraph (c), allows grouping of check valves while testing during a refuel outaae onlv.
- 4. Reason For Request:
The applicable code requirements allow grouping of check valves while testing during a refuel outage onlv. The proposed relief request will permit testing (Le.,
disassembly, inspection, and partial flow testing) of the check valves during any plant mode. Testing of check valves during system outage windows will provide greater flexibility in performance testing, and reduce the burden of testing these valves only during a refueling outage when plant manpower and critical path time is at a premium.
LGS, Units 1 and 2 Relief Request No. 51-VRR-3 Attachment 1 Page 2 of 3
- 5. Proposed Alternative and Basis for Use The proposed alternative test would be to perform code testing on the identified valves approximately every two (2) years, with no restriction on plant mode. This relief is requested in accordance with 10 CFR 50,55a(a)(3)(i) in that the alternative testing provides an acceptable level of quality and safety.
In accordance with GL 89-04, Attachment 1, Position 2, paragraph (c), a sample disassembly and inspection plan has been adopted for the check valves identified above. This plan groups the valves of identical construction, which are used in similar applications, and requires testing (at least) one valve in each group during each refuelina outaae. input criteria to the group selections included valve design features and materials, service conditions, and piping arrangement considerations.
Testing of these valves during any plant mode of operation provides an acceptable level of quality and safety for the following reasons:
All OM Code-I 990 requirements, specifically, the disassembly and inspection, and the refueling outage (approximately two (2) year) frequency, are being met.
The test frequency of approximately every two (2) years is the same length of time between refueling outages. There will be four valves in each group.
There will be one group of valves for each unit. All valves will be tested at least once every six years.
Testing of these valves during plant operation will not lessen the quality of the tests as compared to testing during a refueling outage.
Performing these tests during any mode increases system availability during outages, and reduces manpower demands during outages.
The associated subsystems of RHR will be in a scheduled maintenance window.
Maintenance is scheduled using approved maintenance procedures, which have incorporated the guidance of the maintenance rule. All work will use approved plant procedures, and controls, and will be in regulatory compliance.
RHR maintenance window durations will be governed by the Allowed Outage Times (AOTs) for the RHR system. RHR AOTs are provided in the LGS, Units 1 and 2 Technical Specifications. The limiting LCO for the 'A' and IB' loops is Suppression Pool Cooling Mode of RHR, which has a 72-hour LCO (Technical Specification 3.6.2.3). The ~imitingLCO for the 'C' and 'D' loops is Low pressure Coolant Injection (LPCI), which has a 30-day LCO (Technical Specification 3.5.1). The actual length of the system outage is set by work management
LGS, Units 1 and 2 Relief Request No. 51-VRR-3 Attachment 1 Page 3 of 3 guidelines, which suggest completing the system outage within 50% of the AOT.
However, flexibility exists to use the total AOT.
- 7) The risk associated with the testing (inspection) of the RHR check valves is assessed using the PARAGON program. This is a risk monitor that assesses risk based on individual system or train availabi~i~, in either online or outage mode.
- 8) Corrective actions upon any failure to meet the inspection requirements defined in GL 89-04, Attachment 1, Position 2, Alternatives to Full Flow Testing of Check Valves will require restoration of the valve and retesting. In addition the remaining valves in that group will be inspected during the next available system outage. All valves will be inspected prior to the end of the next refueling outage if not prior. A technical evaluation of failures will be performed to evaluate generic implications that may require immediate response.
- 9) Valves are partially stroke tested quarterly during pump testing. In addition a partial stroke will be performed as part of the post- maintenance (inspection) testing.
- 6. Duration of the Proposed Alternative:
The duration of the proposed alternative is for the remainder of the LGS, Units 1 and 2 second interval. The second interval commenced on January 8,2000 and will conclude on January 7,2010.
- 7. Precedents:
A similar relief request was approved for LGS, Units 1 and 2 (USNRC Letter dated May 5, 2003, Limerick Generating Station, Units I and 2 - Relief from the Requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code,Section XI, Concerning Check Valve lnservice Testing Program (TAC NOS. MB4804 AND M84805))