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

FROM:

Niagara Mohawk Power Corpo

Syracuse, New York Donald PE Disc Mr. George Lear DXSTREBUTXON AFTER ISSUANCE OF OPERATTNG LTCENSE NRC FGRM ~195 U.S. NUCI EAR REGULATORY COMMISS Ig 7dI

" NRC DISTRIBUTION PGR PART 60 DOCKET MATERIAL l va.

OOCKET NUMBER 5

wO PILE NUMBER OATE OP OOCIJMENT 12/16/77 OATE RECEIVEO 12/19/77 PTTER ABORIGINAI SCOP Y OESCRIPTION CINOTORIEEO

~NCLASSIPIEO PROP INPIJT FORM ENCLOSURE NUMBER OF COPIES RECEIVED I SIC,Q

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Consists of infoi concerning licenseeIs review of 304 & 316 austenitic stainless

<steel piping, fitting material It weld metal in thb reactor coolant 'pressure boundary at Nine Mile Point+ ~ ~ ~ +w/att table listing the systems which are in non-compliance+

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PLANT NAMEEine Mile Point Unit No.

1 RDL 12/20/77 (2-P)+(1-P)

SAFETY BRANCH CHlEF:

7 FOR ACTION/INFORMATION INTERNAL.OISTRl BUTION EGFT tT.

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S SENT CATE EXTERNAL DISTRIBUTION CONTROL NUMBER 773500058

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)jgj)Tg)II'ng<['fr~((gpss Donald P. Disc NIAGARAMOHAWKPOWER CORPORATION/300 ERIE BOULEVARDWEST. 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

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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'ij i9r7nEC l9 EAl 9 2z