ML20128L168
| ML20128L168 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 10/07/1996 |
| From: | Mckee P NRC (Affiliation Not Assigned) |
| To: | Feigenbaum T NORTHEAST UTILITIES SERVICE CO. |
| References | |
| TAC-M96566, NUDOCS 9610110328 | |
| Download: ML20128L168 (5) | |
Text
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UNITED STATES jp *l1 P j
NUCLEAR REGULATORY COMMISSION i'
WASHINGTON, D.C. 20565-0001 g
October 7, 1996 Mr. Ted C. Feigenbaum Executive Vice President and Chief Nuclear Officer Northeast Utilities Service Company c/o Mr. Terry L. Harpster Director - Nuclear Licensing Services P.O. Box 128 Waterford, CT 05385
SUBJECT:
RELIEF REQUEST FROM ASME CODE SECTION XI REQUIREMENTS, HADDAM NECK PLANT (TAC NO. M96566)
Dear Mr. Feigenbaum:
In your letter of September 25, 1996, as supplemented on September 30, 1996, the Connecticut Yankee Atomic Power Company (CYAPC0) requested relief from the ASME Section XI requirements regarding corrective action and flaw evaluation i
for pressure boundary leakage.
You submitted this request pursuant to the requirements of 10 CFR 50.55a(g)(5)(iii). The component not meeting the ASME Code requirements is a residual heat removal (RHR) system valve (i.e., RH-V-791A).
During a walkdown, a plant operator noted that this valve had a limited through-wall leak and the valve was therefore declared inoperable and closed (the leakage stopped after the valve was closed). The valve body is cast ASTM A351 CF8M stainless steel.
Your staff determined the leakrate to be
<0.1 ml/ min when the valve is open (the valve is currently shut). You requested this relief to allow CYAPC0 to declare the valve operable but degraded.
This would allow CYAPC0 to use the RHR system while offloading the fuel from the reactor vessel. Once the fuel is offloaded, CYAPC0 plans to inspect and repair or replace the valve in accordance with ASME Code requirements.
You stated that you performed a radiographic examination of this valve to attempt to characterize the leakage path.
However, the radiographic examination was not able to identify the source of the leakage. A liquid penetrant examination did not find any structurally significant flaws.
Your staff determined that the ASME Code-required examination and repair was impractical.
The Code of reference for your plant is the 1983 Edition of ASME Section XI, through Summer 1983 Addenda. The valve is Class 2 and the requirements of IWC-3000 apply. The ASME Code requires that there be no flaws greater than 75% through wall.
Since the valve is leaking slightly, the flaw is 100% through wall and therefore does not meet ASME Code requirements.
You stated that you considered two repair options before concluding that the ASME Code requirements were impractical. The first was to isolate the valve and replace it.
Since isolation valves are not available, you would have to rely on freeze seals as the reactor coolant system boundary.
You concluded this repair method resulted in a reduction in plant safety and was therefore impractical. The second option involved an ASME Code-repair without isolating the valve. This method was also determined to be impractical since I
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j l-Ted C. Fiegenbaum i (1) welding could result in a growth of the existing defects, (2) water in the valve body would degrade the quality of the weld, and (3) the ASME Code-required volumetric examination could not be performed.
As an alternative to the ASME Code evaluation requirements, you conducted a structural assessment of the valve using the limit load methodology described in the Electric Power Research Institute's Ductile Fracture Handbook.
In addition, you used the linear elastic fracture mechanics approach for through-wall defects given in the NRC's Generic Letter 90-05.
Your staff concluded that the allowable flaw size was much greater than pin hole leak observed on the outer surface of the valve body.
Therefore, you determined that the valve is expected to maintain its structural integrity during design basis load combinations through the end of the refueling operations (estimated to be less than 14 days).
Your staff also concluded that the hydraulic performance of the valve will not be affected by this small leak.
As compensatory measures, you committed to use a video camera to allow operators in the control room to view the valve remotely and monitor valve leakage.
If the valve begins to leak a significant amount, it will be closed to minimize the leakage.
You also noted that you have reviewed the existing abnormal operating procedures and conclude they are adequate to isolate the leakage path and restore alternate core cooling systems to replace the RHR system should a catastrophic failure of the valve occur.
Additionally, the valve is expected to see temperatures much less than 200'F and a pressure less than 150 psig.
These conditions are well below the design temperature of 400*F and design pressure of 500 psig.
The NRC staff has reviewed your request for relief from the Section XI requirement discussed above.
The staff concludes that imposing the requirements on the facility with the existing plant condition could result in an unacceptable repair because of insufficient isolation capability in the current plant configuration.
Based on the alternate examination and compensatory measures taken or planned, the staff agrees with your determination that the structural integrity of the valve will be inaintained during the duration of the fuel offload. Accordingly, the NRC staff finds that the ASME Code requirements are impractical for these plant conditions and that relief is granted as requested pursuant to 10 CFR 50.55a(g)(6)(i),
provided the compensatory measures described above are implemented.
The NRC staff finds that such relief will not endanger life or property or the common defense and security and is otherwise in the public interest giving due consideration to the burden upon CYAPC0 that could result if the requirements were imposed on your facility.
Based on the above evaluation, the staff concurs that the RHR valve can be considered degraded but operable since integrity will be maintained and the leakage will not affect the hydraulic performance of the RHR system until an
s Ted C. Fiegenbaum.
l i
ASME Code-repair can be safely performed after the fuel has been transferred to the spent fuel pool.
This completes our efforts on this issue and closes l
out TAC No. M96566.
l l
Sincerely, F/77L Phillip F.
cKee, Director Northeast Utilities Project Directorate Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation Docket No. 50-213 cc:
See next page I
J
Ted C. Feigenbaum October 7, 1996 ASME Code-repair can be safely performed after the fuel has been transferred to the spent fuel pool. This completes our efforts on this issue and closes out TAC No. M96566.
Sincerely, Original signed by:
Phillip F. McKee, Director Northeast Utilities Project Directorate Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation Docket No. 50-213 cc:
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l T. Feigenbaum Haddam Neck Plant Northeast Utilities Service Company cc:
Lillian M. Cuoco, Esq.
Mr. S. E. Scace, Vice President Senior Nuclear Counsel Nuclear Reengineering Implementation Northeast Utilities Service Company Northeast Utilities Service Company P.O. Box 270 P.O. Box 128 Hartford, CT 06141-0270 Waterford, CT 06385 Mr. Kevin T. A. McCarthy, Director Regional Administrator Monitoring and Radiation Division Region !
Department of Environmental Protection U.S. Nuclear Regulatory Commission 79 Elm Street 475 Allendale Road Hartford, CT 06106-5127 King of Prussia, PA 19406 Mr. Allan Johanson, Assistant Director Board of Selectmen Office of Policy and Management Town Office Building i
Policy Development and Planning Division Haddam, CT 06438 80 Washington Street Hartford, CT V6106 Resident Inspector Haddam Neck Plant Mr. J. J. LaPlatney c/o U.S. Nuclear Regulatory Commission Haddam Neck Unit Director 361 Injun Hollow Road i
Connecticut Yank e Atomic Power Company East Hampton, CT 06424-3099 362 Injun Hollow.aad East Hampton, CT 06424-3099 Mr. A. M. Callendrello Licensing Manager - Haddam Neck Mr. D. B. Miller, Jr.
North Atlantic Energy Service Corp.
Senior Vice President P.O. Box 300 Nuclear Safety and Oversight Seabrook, NH 03874 Northeast Utilities Service Company P.O. Box 270 Mr. James S. Robinson Waterford, CT 06141-0270 Manager, Nuclear Investments and Administration Mr. E. A. DeBarba New England Power Company Vice President - Nuclear Technical Services 25 Research Drive Northeast Utilities Service Company Westborough, MA 01582 P.O. Box 128 Waterford, CT 06385 Mr. B. D. Kenyon President - Nuclear Group Mr. F. C. Rothen Northeast Utilities Service Company Vice President - Nuclear Work Services P. O. Box 128 Northeast Utilities Service Company Waterford, CT 06385 P.O. Box 128 Waterford, CT 06385