ML20070S034
| ML20070S034 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 02/01/1983 |
| From: | Devincentis J PUBLIC SERVICE CO. OF NEW HAMPSHIRE, YANKEE ATOMIC ELECTRIC CO. |
| To: | Knighton G Office of Nuclear Reactor Regulation |
| References | |
| SBN-450, NUDOCS 8302040210 | |
| Download: ML20070S034 (3) | |
Text
9 M.I SEASROOK STATION Engineesing CNies:
1671 Wonsseer Rood Presningham, Mossochveens 01701 gggg (617)- s72 3100 February 1, 1983 SBN-450 T.F. B7.1.2 United States Nuclear Regulatory Commission Washington, D. C. 20555 Attention:
Mr. George W. Knighton, Chief Licensing Branch No. 3 Division of Licensing
References:
(a) Construction Permits CPPR-135 and CPPR-136, Docket Nos. 50-443 and 50-444
Subject:
Open Item Response:
(SRP 5.3.1; Materials Engineering Branch
Dear Sir:
We have enclosed a response to the open item regarding reactor vessel closure studs. This item was discussed with representatives of the Materials l
Engineering Branch in meetings conducted on January 10-12, 1983.
l The enclosed response will be included in OL Application Amendment 49.
Very truly yours, l
YANKEE ATOMIC ELECTRIC COMPANY l
[
J. DeVincentis Project Manager ALL/fsf cc: Atomic Safety and Licensing Board Service List h
l l
8302040210 830201 PDR ADOCK 05000443 1
E PDR 1
1 1000 Eim St.. P.O. Box 330. Monchester. NH O3105. Telephone (603) 6694000. TWX 7102207595 1
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ASLB SERVICE LIST Phi).4p Ahrena Esquire Assistant Attorney General Department of the Attorney General Augusta, ME 04333 Representative Beverly Hollingworth Coastal Chamber of Commerce 209 Winnacunnet Road Hampton, NH 03842 William S. Jordan, III, Esquire Harmon & Weiss 1725 I Street, N.W.
Suite 506 Washington, DC 20006 E. Tupper Kinder, Esquire Assistant Attorney General Office of the Attorney General 208 State House Annex Concord, NH 03301 Robert A. Backus, Esquire 116 Lowell Street P.O. Box 516 Manchester, NH 03105 Edward J. McDermott, Esquire Sanders and McDermott Professional Association 406 Lafayette Road Hampton, NH 03842 Jo Ann Shotwell, Esquire Assistant Attorney General Environmental Protection Bureau Department of the Attorney General One Ashburton Place, 19th Floor Boston, MA 02108 4
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RESP 0B.SE TO.0 PEN.IIE!LREGABRING_jlEA.CTOR_yESSEL CLOSUR.E STUDS (5.3 l
We'stinghouse is in agreement with Regulatory Guide 1.55 except for material and tensile strength guidelines.
Westingnouse has specified both 45 ft lb and 25 mils lateral expansion for control of fracture toughness determined by Charpy-V testing, required by the ASME Boiler and Pressure Vessel Code,Section III, Summer 1973 Addenda and 10CFR Part 50, Appendix G (July 17, 1973, Paragraph IV.A.4).
These toughness requirements assure optimization of the stud bolt material tempering operation with the accompanying reduction of the tensile strength level when compared with previous ASME Boiler and Pressure Vessel Code requirements.
The specification of both impact and maximum tensile strength as stated in the guide results in unnecessary hardship in procurement of material without any additional improvement 4
in quality.
The closure stud bolting material is procured to a minimum yield strength of 130,000 psi and a minimum tensile strength of 145,000 psi. This. strength level is compatible with the fracture toughness requirements of 10CFR 50, Appendix G (July,1973, Paragraph 1.C), although higher strength level Stress corrosion bolting materials are permitted by the code.
has not been observed in reactor vessel closure stud bolting manu-factured from material of this strength ' level.
Accelerated stress corrosion test data do exist for materials of 170,000 psi minimum yield strength exposed to marine water environ-ments stressed to 75 percent of the yield strength (given in Reference 2 of the guide).
These data are not considered applicable to Westinghouse reactor vessel closure stud bolt-ing because of the specified yield strength differences and a less severe environment; this has been demonstrated by years of satisfactory service experience.
The ASME Boiler and Pressure Vessel Code requirement for toughness for reactor vessel bolting has precluded the guide's additional recommendation for tensile strength limitation, since to obtain the require toughness levels, the tensile strength levels are reduced.
Prior to 1972, the Code required a 35 ft Ib toughness level which provided maximum tensile strength levels ranging from approximately 155 to 178 kpsi (Westinghouse review of limited data - 25 heats).. After publication of the Summer 1973 Addenda to the Code and 10CFR Part 50 Appendix G, wherein the toughness requirements were modified to 45 ft Ib with 25 mils laterial expansion, all bolt material data reviewed on Westinghouse plants showed tensile strengths of less than 170 kpsi.
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