ML20059F290
| ML20059F290 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 01/07/1994 |
| From: | Kuo P Office of Nuclear Reactor Regulation |
| To: | Opeka J CONNECTICUT YANKEE ATOMIC POWER CO., NORTHEAST NUCLEAR ENERGY CO. |
| References | |
| TAC-M88055, NUDOCS 9401130257 | |
| Download: ML20059F290 (4) | |
Text
-_
January 7,1994 Docket No. 50-245 Mr. John F. Opeka Executive Vice President, Nuclear Connecticut Yankee Atomic Power Company Northeast Nuclear Energy Company Post Office Box 270 Hartford, Cunnecticut 06141-0270
Dear Mr. Opeka:
SUBJECT:
MILLSTONE NUCLEAR POWER STATION, UNIT 1 - REQUEST FOR RELIEF FROM
~
ASME CODE REPAIR REQUIREMENTS FOR ASME CLASS 3 PIPING (TAC NO. M88055)
By letter dated October 20, 1993, Northeast Nuclear Energy Company requested relief from Code repair requirements for a pin hole leak in a moderate energy class 3 pipe at Millstone Nuclear Power Station, Unit 1.
The leak was detected at the junction of a 12-inch nominal pipe size (NPS), standard schedule (0.375" wall), branch connection on a 24-inch NPS service water discharge header.
The water is leaking through the weep hole in the reinforcing saddle.
The staff has reviewed the relief request dated October 20, 1993, and concluded that relief where Code requirements are impractical and imposing alternative requirements are authorized by law and will not endanger life or property or the common defense and security and are otherwise in the public interest, given due consideration to the burden upon the licensee and facility that could result if the Code requirements were imposed on the facility.
Pursuant to 10 CFR 50.55a(g)(6)(i) and consistent with the guidance in Generic Letter 90-05, relief is granted until the next scheduled outage exceeding 30 days, but no later than the next refueling outage.
The temporary non-Code repair must then be replaced with a Code repair.
A copy of the Safety Evaluation is enclosed. If you have any questions please call Jim Andersen at (301)504-1437.
Sincerely, 9401130257 940107 Original signed by PDR ADOCK 05000245 P. T. Kuo, Acting Director i200_,3 Project Directorate 1-4 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation
Enclosure:
Safety Evaluation l
rmu qs pn W %pH cc w/ enclosure:
See next page fi!M ESLC Ui2$ 6 kN bn b DISTRIBUTION:
Docket File NRC & Local PDRs JStolz GHill (2)
PDI-4 Plant ERossi SNorris ACRS (10) f TMurley JLieberman JAndersen OPA FMiraglia SVarga OGC OC/LFDCB LCallanT JCalvo EJordan VMcCree, ED0 pt() i LDoerflein, RGI t
- SEE PREVIOUS CONCURRENCE I
\\
D:PDI[4 h 1
OGC*
4 OFFICE LA:PDI-4*
PM:PDI-4*
j NAME SNorris JAndersen:td PKuoLActing MYoung DATE 12/22/93 12/22/93e b k
//6 /
01/03/94
/ /
OFFICIAL RECORD COPY Document Name:
G:\\ANDERSEN\\88055
/f
+,
UNITED STATES
[
j NUCLEAR REGULATORY COMMISSION W
WASHINGTON, D.C. 20666-0001 January 7,1994 Docket No. 50-245 Mr. John F. Opeka Executive Vice President, Nuclear Connecticut Yankee Atomic Power Company Northeast Nuclear Energy Company Post Office Box 270 Hartford, Connecticut 06141 0270
Dear Mr. Opeka:
SUBJECT:
MILLSTONE NUCLEAR POWER STATION, UNIT 1 - REQUEST FOR RELIEF FROM ASME CODE REPAIR REQUIREMENTS FOR ASME CLASS 3 PIPING (TAC N0. M88055)
By letter dated October 20, 1993, Northeast Nuclear Energy Company requested relief from Code repair requirements for a pin hole leak in a moderate energy class 3 pipe at Millstone Nuclear Power Station, Unit 1.
The leak was detected at the junction of a 12-inch nominal pipe size (NPS), standard schedule (0.375" wall), branch connection on a 24-inch NPS service water discharge header. The water is leaking through the weep hole in the reinforcing saddle.
The staff has reviewed the relief request dated October 20, 1993, and concluded that relief where Code requirements are impractical and imposing alternative requirements are authorized by law and will not endanger life or property or the common defense and security and are otherwise in the public interest, given due consideration to the burden upon the licensee and facility that could result if the Code requirements were imposed on the facility.
Pursuant to 10 CFR 50.55a(g)(6)(i) and consistent with the guidance in Generic Letter 90-05, relief is granted until the next scheduled outage exceeding 30 days, but no later than the next refueling outage. The temporary non-Code repair must then be replaced with a code repair.
A copy of the Safety Evaluation is enclosed. If you have any questions please call Jim Andersen at (301)504-1437.
Sincerely,
. T. Kuo, Acting Director roject Directorate I-4 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation
Enclosure:
Safety Evaluation cc w/ enclosure:
See next page
j I
i Mr. John F. Opeka Millstone' Nuclear Power Station Northeast Nuclear Energy Company Unit 1 cc:
l Gerald Garfield, Esquire R. M. Kacich, Director Day, Berry and Howard Nuclear Planning, Licensing & Budgeting Counselors at Law Northeast Utilities Service Company City Place Post Office Box 270 Hartford, Connecticut 06103-3499 Hartford, Connecticut 16141-0270 J. P. Stetz, Vice President J. M. Solymossy, Director Haddam Neck Plant Nuclear Quality and Assessment Services Connecticut Yankee Atomic Power Company Northeast Utilities Service Company 362 Injun Hollow Road Post Office Box 270 East Hampton, Connecticut 06424-3099 Hartford, Connecticut 06141-0270 Kevin T. A. McCarthy, Director Regional Administrator Monitoring and Radiation Division Region I Department of Environmental Protection U.S. Nuclear Regulatory Commission 79 Elm Street 475 Allendale Road i
Hartford, Connecticut 06106-5127 King of Prussia, Pennsylvania 19406 Allan Johanson, Assistant Director First Selectmen Office of Policy and Management Town of Waterford Policy Development and Planning Division Hall of Records 80 Washington Street 200 Boston Post Road Hartford, Connecticut 06106 Waterford, Connecticut 06385 S. E. Scace, Vice President P. D. Swetland, Resident Inspector i
Nuclear Operations Services Millstone Nuclear Power Station Northeast Utilities Service Company c/o U.S. Nuclear Regulatory Commission Post Office Box 270 Post Office Box 513 Hartford, Connecticut 06141-0270 Niantic, Connecticut 06357 i
H. F. Haynes, Nuclear Unit Director Donald B. Miller, Jr.
Millstone Unit No. 1 Senior Vice President 3
Northeast Nuclear Energy Company Millstone Station Post Office Box 128 Northeast Nuclear Energy Comoany Waterford, Connecticut 06385 Post Office Box 128 Waterford, Connecticut 06385 Nicholas S. Reynolds Winston & Strawn 1400 L Street, NW Washington, DC 20005-3502 m
1
\\
f a a%g
.,d i
UNITED STATES
[
. j NUCLEAR REGULATORY COMMISSION i
I
'C WASHINGTON, D.C. 20556-0001
,o
+....
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION '
RE0 VEST FOR RELIEF FROM ASME CODE REPAIR RE0VIREMENTS i
FOR ASME CODE CLASS'3 PIPING 4
NORTHEAST NUCLEAR ENERGY COMPANY MILLSTONE NUCLEAR POWER STATION. UNIT 1 DOCKET NO. 50-245
)
1.0 BACKGROUND
Temocrary Non-Code Reoairs The Code of Federal Regulations at 10 CFR 50.55a(g) requires nuclear power facility piping and components to meet the applicable requirements of Section XI of the ASME Boiler and Pressure Vessel Code (hereafter called the Code).3 Section XI of the Code specifies Code-acceptable repair methods for flaws that exceed Code acceptance limits in piping that is in service. A Code repair is required to restore the structural integrity of flawed Code piping, independent of the operational mode of the plant when the flaw is detected.
Those repairs not in compliance with Section XI of the Code are non-Code repairs. However, the required Code repair may be impractical for a flaw detected during plant operation unless the facility is shut down.
Pursuant to 10 CFR 50.55a(g)(6)(i), the Commission will evaluate determinations of impracticality, and may grant relief and may impose alternative requirements.
Generic Letter (GL) 90-05, entitled " Guidance for Performing Temporary Non-Code Repair of ASME Code Class 1, 2, and 3 Piping," and dated June 15, 1990, provides guidance for the staff in evaluating relief requests submitted by licensees for temporary non-Code repairs of Code class 3 piping.
The Commission may grant relief based en a staff evaluation considering the guidance in GL 90-05.
l Licensee's Relief Reauest By letter dated October 20, 1993, Northeast Nuclear Energy Company (NNECO) requested relief from Code repair requirements for a pin hole leak in a moderate energy class 3 pipe at.Hillstone Nuclear Power Station, Unit 1.
The leak was detected at the junction of a 12-inch nominal pipe size (NPS),
standard schedule (0.375" wall), branch connection on a 24-inch NPS service water discharge header.
The water is leaking through the weep hole in the reinforcing saddle.
The service water (SW) system conveys ambient temperature sea water at 150 psig (design). The pipe is lined carbon steel (SA-53 gr. B).
l I
, Because of its location on a common discharge header, the leak cannot be 1
isolated.
Removing the 24-inch header from service would mean shutdown of various turbine building safety related systems / equipment and require unit shutdown.
2.0 DISCUSSION The pin hole leak was believed to be initiated on the pipe I.D.*at a local lining failure or weld defect.
It was located under the 12-inch branch connection reinforcing saddle on the header. Ultrasonic examination (UT) of the reinforcing saddle and surrounding pipe walls revealed no degradation of any of the components, thus supporting the judgement that the flaw was small.
Due to the leak location a flaw evaluation was impractical.
Instead, a structural assessment was performed assuming the reinforcing saddle was the sole load bearing component. This analysis showed that the system retains adequate structural integrity for continued service.
The leak rate was small.
For housekeeping purposes, a wooden dowel was inserted into the reinforcing saddle weep hole, and the leakage stopped.
Due to the very low operating pressure (slight vacuum) at this point of the system, no spraying of water on other equipment would occur.
Loss of flow to essential equipment would not occur due to the leak location being in the discharge header.
Since the structural analysis had shown safe margins, NNEC0 planned to leave the leak as-is.
Code repair would occur at the next refueling outage, currently scheduled for January 1994.
For monitoring purposes, NNECO has committed to the guidance of GL 90-05.
Visual inspections will occur once per shift.
Follow-up UT will occur every two weeks for the first month, and monthly thereafter. An augmented inspection of other similar areas of the system revealed no degradation.
3.0 CONCLUSION
l NNEC0 has committed to the guidance provided in GL 90-05. NNECO has an effective program for identifying and evaluating SW system problems and has satisfied the safety guidance of the generic letter.
Because the leak cannot be isolated and compliance with the Code would require plant shutdown, the staff concludes that the Code requirements are impractical. Therefore, relief may be granted based upon NNEC0's commitment to perform alternative repair activities consistent with GL 90-05.
This relief is authorized by law and will not endanger life or property or the common defense and security and are otherwise in the public interest, given due consideration to the burden upon the licensee and facility that could result if the Code requirements were imposed on the facility.
Pursuant to 10 CFR 50.55a(g)(6)(i) and consistent with the guidance in GL 90-05, relief is granted until the next scheduled outage exceeding 30 days, but no later than the next refueling outage. The temporary non-Code repair must then be replaced with a Code repair.
Principal Contributor:
G. Hornseth Date: January 7, 1994
.~...
.1