ML17037B506

Letter Regarding Review of All 304 and 316 Austenitic Stainless Steel Piping, Fitting Material and Weld Metal in the Reactor Coolant Pressure Boundary at Nine Mile Point Unit 1 with Respect to the Requirements of NUREG-0313

ML17037B506
Person / Time
Site:	Nine Mile Point
Issue date:	12/16/1977
From:	Dise D Niagara Mohawk Power Corp
To:	Lear G Office of Nuclear Reactor Regulation
References
Download: ML17037B506 (8)

Text

DXSTREBUTXON AFTER ISSUANCE OF OPERATTNG LTCENSE NRC FGRM ~195 U.S. NUCI EAR REGULATORY COMMISS OOCKET NUMBER Ig 7dI 5 wO PILE NUMBER

" NRC DISTRIBUTION PGR PART 60 DOCKET MATERIAL l va. FROM: OATE OP OOCIJMENT Niagara Mohawk Power Corpo 12/16/77 Mr. George Lear Syracuse, New York OATE RECEIVEO Donald PE Disc 12/19/77 PTTER CINOTORIEEO PROP INPIJT FORM NUMBER OF COPIES RECEIVED ABORIGINAI ~NCLASSIPIEO SCOP Y I SIC,Q OESCRIPTION ENCLOSURE Consists of infoi concerning licenseeIs~

review of 304 & 316 austenitic stainless

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<steel piping, fitting material It weld

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metal in thb reactor coolant 'pressure boundary at Nine Mile Point+ ~ ~ ~ +w/att table listing the systems which are in non- compliance+ ~~~~

PLANT NAMEEine Mile Point Unit No. 1 RDL 12/20/77 (2-P)+(1-P)

SAFETY FOR ACTION/INFORMATION BRANCH CHlEF: 7 INTERNAL.OIST Rl BUTION EGFT tT. MCGO

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EXTERNAL DISTRIBUTION CONTROL NUMBER p TC NS jc 773500058 f:CRS 16 C S SENT CATE

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)jgj)Tg)II'ng<['fr~(( gpss Donald P. Disc NIAGARA MOHAWK POWER CORPORATION/300 ERIE BOULEVARD WEST. SYRACUSE, N.Y. 13202/TELEPHONE (315) 474-1511 Vice President Engineering December 16, 1977 Director of Nuclear, Reactor Regulation Attn: Mr. George Lear, Chief Operating Reactors Branch f/3 U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Re: Nine Mile Point Unit 1 Docket No. 50-220 DPR-63 Gentlemen:

Your letter of September 16, 1977 requested that all 304 and 316 austenitic stainless steel piping, fitting material and weld metal in the reactor coolant pressure boundary at Nine Mile Point Unit 1 be reviewed with respect to the requirements of NURFG-0313.

The results of this review indicate that piping and material used at Nine Mile Point Unit 1 do not comply fully with the requirements of NUREG-0313 for minimizing the susceptibility to stress corrosion cracking. Table 1 lists the systems which, are in non-compliance.

With regard to intergranular, stress corrosion cracking, "as-welded" Type 316 stainless steel should not be classified with Type 304 stainless steel., This conclusion is based on full-scale laboratory pipe, tests and the fact that Niagara Mohawk is not aware of any instances where intergranular stress corrosion cracking has occurred in Type 316 stainless steel pressure boundary lines. Since our recirculation system is built of this Type 316 stainless steel, it is not planned to increase the inservice inspection associated with this system.

It is not practical to replace piping in the service sensitive systems listed in Table 1 because of the excessive occupational exposures that would be incurred and extensive work involved with primary containment penetrations. However,

'iagara Mohawk plans to implement increased levels of inservice inspection as outlined in NUREG-0313 for. systems built of Type 304 stainless steel and to adopt the model Technical Specifi-cation on leakage detection.

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Since austenitic stainless steel piping has an inherent high material toughness, stress corrosion cracking will not cause a rapidly, propagating failure. Therefore, implementation of increased inservice inspection, and,coolant boundary leakage detection will enhance the detection of cracks before they would propagate to create a significant safety hazard. Should any indications be found as a result of the above inspections, appropriate replacement schedules will, be developed.

A license amendment dated December 16, 1977 covering both inservice inspection and leakage detection is being transmitted under separate cover.

Very truly yours, NIAGARA MOHAWK POWER CORPORATION DONALD P. DISE Vice President-Engineering PEF/szd Attachment

4 TA'BLE 'l:

REACTOR COOLANT PRESSURE BOUNDARY PIPING CONTAINING 304 AND 316 STAINLESS STEEL NON-SERVICE SENSITIVE

l. Reactor Recirculation

2. Clean-Up

3. Reactor Drain SERVICE SENSITIVE

1. Core Spray

2. Shutdown Cooling

3. Emergency Condensers

4. Liquid Poison

5. Reactor Head Spray

6. Recirculation Bypass

7. Control Rod Drive Return

8. Reactor Instruments

REE'CIVED DGt'Ut<EHT PROC'SSfVQ Ufl'i j i9r7nEC l9 EAl 9 2z