ML17037C462

Letter Transmitting Proposed Changes to Technical Specifications for the Maintenance of Pressure Suppression Chamber Integrity

ML17037C462
Person / Time
Site:	Nine Mile Point
Issue date:	02/15/1974
From:	Raymond P Niagara Mohawk Power Corp
To:	Ziemann D US Atomic Energy Commission (AEC)
References
Download: ML17037C462 (8)

Text

AEC DIS "BUTION FOR PART 50 DOCKET MATE (TEMPORARY FORM) CONSOL NO:

FILE:

FROM: DATE OF DOC DATE REC'D LTR MEMO OTHER Niagara Mohawk Power Corporation Syracuse, N.Y. 13202 Philip D. Raymond 2<<15-74 2-20-74 To: ORIG CC OTHER SENT AEC PDR SENT LOCAL PDR XXX D.L. Ziemann 1 signed CLASS UNCLASS PROP INFO XNPUT NO C S 'REC'D DOCKET NO:

XXX 40 50-220 DESCRXPTION: ENCLOSURES:

Ltr re our 12-19-73 ltr...trans the following... Proposed changes to tech specs.

ACKNOW,ED"ED (40 cys encl rec'd)

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Mr. Dennis L. Ziemann Chief, Operating Reactors Branch 82 Directorate of Licensing United States Atomic Energy Commission Washington, D. C. 20545 o

Dear Mr. Ziemann:

• Re: Nine Mile Point Unit 1 F I

Docket No. 50-220 In response to your letter of December 19, 1973, a proposed Technical Specification for the maintenance of pressure suppression chamber integrity at Nine Mile Point Unit 1 is attached. This Speci-fication includes a Limiting Condition for Operation, a Surveillance Requirement, and Bases.

We have been advised that the general subject of containment surveillance has been placed on the agenda of the Subcommittee for Metal Containment, Subsection NE, Section III, ASME Boiler and Pressure Vessel Code. Accordingly, the attached Specification should be con-sidered an interim requirement which may be amended to reflect applicable ASME Code requirements if and when they are formulated.

Very truly yours, Philip D. ond Vice Presi ent Engineering CVM/sj z Attachment CA 4'OP Pg<>~lp Oc '+Z@e O,

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,3.3.8 Pres sure', Supp ss i on Chamber I nteg r i ty Applies to the overall integrity of the pressure suppression chamber.

~Ob e'ctive:

To assure that the pressure suppression chamber is capable of limiting radiation exposure to the public to the values specified in 10 CFR 100, and to monitor the dynamic effects on the pressure suppression chamber of relief valve blowdowns into the chamber water.

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'if'henever the reactor coolant system temperature is above 215 F, the pressure suppression chamber integrity shall be maintained and chamber wall thickness shall be greater than 0.420 inches.

4.3.8 Pressure Suppression Chamber Integrity Applies to the periodic inspection of the pressure suppression system.

~ob ective:

To assure that the pressure suppression chamber integrity is within the specified limits.

a. Once each operating cycle during the major refueling outage, five (5) preselected areas of the suppression chamber, wall shall be ultrasonically examined for section thickness.

b. A visual inspection of the suppression chamber interior, including water line regions and supports shall be made at each major refueling outage.

BASES The values specified for minimum wall thickness of the pressure suppression chamber have been established based upon the design of the pressure suppression chamber in conformance with Section III, Class B of the ASME Code., The design specification allows a I/16 inch corrosion allowance to the unpainted interior surface of the chamber. Thus with a design thickness of 0.3975 inch the corrosion allowance increases the thickness to 0.460 inch. How-ever, manufacturing increases the thickness to a,nominal 0.500 inch allowing 0.1025 inch greater than design. The limit of 0.420 inch provides a maigin over the design thickness and assures suppression chamber integrity.

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BASES, Continued The inspection frequency as established is conservative based on the observed change in thickness as determined from 1972 measure-ments to 1973 measurements in which there was no perceptible change after more than 20 individual relief valve operations.

To determine the status of the pressure suppression system, a visual inspection of the suppression chamber interior surFaces and structure, with water at its normal elevation, will be made at each major refueling outage. This inspection will assure that any gross defects are detected.

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