ML17037C513

Letter Submitting Description of Proposed Modification. Change Consists of Providing an Extension to the Existing Reactor Building to Facilitate Spent Fuel Handling Operations

ML17037C513
Person / Time
Site:	Nine Mile Point
Issue date:	01/31/1974
From:	Raymond P Niagara Mohawk Power Corp
To:	Skovholt D US Atomic Energy Commission (AEC)
References
Download: ML17037C513 (12)

Text

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AZC ~DISTRIBUTION FOR,'PART 50 DOCKET 1Q~PIAL (TEMPORARY> FORM) CONTROL NO: 961 FILE:4 FROM: DATE OF DOC DATE REC'D LTR MEMO RPT OTHER Niagara Mohawk Power Corp.

Syracuse, N. Y. 13202 lgl>>74 2-4-74 P. D. Raymond TO: ORIG CC OTHER SENT AEC PDR D. "J. Skovholt 1 signed SENT LOCAL PDR CLASS UNCLASS PROP INFO INPUT NO C S REC'D DOCKET NO'0-220 XXZX XXXZX DESCRIPTION: ENCLOSURES:

Ltr trans the following: Request for a change to Prov Opr Lic to allow extension to 'the existing building to" facilitate spent fuel handling operations DO NOT REMOVE ACKNOWLEDGED PLANT N<~: Nine Mile Point Unit f51 FOR ACTION/INFORMATION 2-4-74 GC BUTLER(L) SCHMENCER(L) vrZIEMANN(L) REGAN(E)

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Jl Regulatory Docket File NIAGARA MOHAWK POWER CORPORATION

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NIAGARA ~gf'OHAWK

,~fr 300 ERIE BOULEVARD WEST SYRACUSE. N. Y. I3202 FEB 4 )974 e ILAIL SECTION GQCKET CORK January 31, 1974 Oi

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EBQ Igpq Mr. Donald J. Skovholt IL~ ~log,'~

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Assistant Director for Operating Reactors +4am@

ffIaIIEIf Directorate of Licensing '@all-'SecIIRI United States Atomic Energy Commission Washington, D. C. 20545 O I

Dear Mr. Skovholt:

Re: Nine Mile Point Unit 1 Docket No. 50-220 Pursuant to Section 50.59 of the Commission's Regulations, Niagara Mohawk plans to make a change in its facility under Provisional Operating License No. DPR-17. Briefly, this change consists of providing an extension to the existing reactor building to facilitate spent fuel handling operations.

For your information, a description of the proposed modification, including a safety evaluation, is attached. This evaluation shows that the probability of occurrence and the consequences of an accident or malfunction would be decreased, and margins. of safety for spent fuel handling operations increased by this change.

The proposed modification has been reviewed and approved by the Safety Review and Audit Board and by the Site Operations Review Committee.

Both groups are of the opinion that no additional possibility for an accident or malfunction of a different type than evaluated in the Safety Analysis Report would be created. They have, also concluded that this change will not present a significant hazards consideration, but rather will enhance plant safety.

We are enclosing ten additional copies for your convenience.

Very truly yours, Philip D. Ra ond Vice President Engineering Enclosures 869;

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>V Regulatory Docket Fiie REACTOR BUILDING EXTENSION

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geegyid,i/Lit Dot I.. .'ntroduction The present. design=of the reactor building includes a double seal system"-to ensure-.secondary containment integrity.'. During normal .operation,. building-integrity is maintained by outer doors in the railroad bay. When access to.

,.the building is required through the railroad,bay doors,'he bay can be isolated from the rest of the reactor building; As described in the FS'AR a bolted hatch cover at Elevation 281 feet is used for this purpose.

Since the initial operation of Nine Mile Point Unit 1, tne designs of spent fuel casks have changed.

r The existing=building design does not'llow the

,- use of current railroad cask designs. -In order to bring. the rail car into the building and maneuver the cask=into position for hoisting up to the operating *floor, .the "end: of. the rail car would have to extend through the . '

outer doorway of the railroad bay. Since the hatch would have to be 'open for use'f the reactor building crane, secondary containment integrity.

could not be maintained.

In order to accomodate use of, current railroad casks while maintaining

.secondary containment; a.change to,the existing reactor building is pl~~~~d An extension structure is to be added to the reactor building so that spent I

fuel loading and shipping .can be performed in a mope expeditious manner, The extension will be part of secondary containment and wi11 have an outer door seal. 'Th'e present outer door will remain and will be used to isolate this extension structure from the. reactor building when access to the new

-bay is'required. The need for the hatch .would, be eliminated.

(1) Yolume I, Section YI.B.2.

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The modification involves the addition of a 20 foot by 20 foot by 80 foot long air lock with, a 'swing dood and an airtight seal. The track bay extension will be equipped with a motor operated double swing door 16 feet 0 inches wide by 17 feet 6 inches high. The door can also be operated manually, and is designed to resist .an internal:or external load of'0 psf. 'A one-piece inflatable seal of Reinforced Ethylene Propylene.Diene Monomer is provided around the perimeter of each half of the door. 'he entire contact area of the in>latable seal will expand approximately 3/4 inch under pressure. The

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seal material will remain pliable and seal at- temperatures of -20F to 210F.

As shown on Figure 1 the extension structure has a personnel access door on

'he north'side. adjacent to the existing. structure.

An airtight access passageway will be constructed from the existing access door to this door in the reactor building extension. Procedural'ontrol only

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permits one of these three passageway doors to be open. The doors will have local alarms such that personnel about-to enter or leave are alerted to the condition of the alternate doors.

Sufficient room is available to contain the rail car with a spent fuel shipping cask and provide adequate maneuvering room for the rail car during cask loading and unloading. The proposed modification is shown in Figure l.

This addition to the reactor bu'ilding wi-1'1 be d. signed to meet all'he requirements of the original reactor building as described in the FSAR--

The track bay extension will be attached to the existing reactor building by an airtight seal formed between the two buildings.

Volume I, Section YI.B.I

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Page 3 The outside paneling material will be identical to that used above the operat-'ng floor in the reactor building. The insulated metal wall- panels 'and the metal roof. dec): are of leak.-tight construction'. The roof deck is covered with a five-ply .tar and felt built-up roof.

The new and existing doors will be alarmed and procedural control will ensure that only one door in series may be open at one time. Secondary containment will be maintained at all times.

This addition alsc. allows the hatch cover to be permanently removed and still maintain secondary containment. At the present time hatch cover removal takes about 12 ho<<rs. The operation involves unbolting or rebolting the hatch cover. Elimination of this step will optimize cask handling operations.

A retest of secondary containment will, be performed after the 'addition'as been completed to ensure that leakage characteristics have not be'en changed.

I I I; 'Sunmar The planned modifications reduce fuel cask handling operations. Therefore, the. probability of occurence of, an accident or malfunction during these opera-=

tions is reduced. No change to the basic functions of'he reactor building and railroad bay have been made. Therefore, no new modes of accidents or malfunctions have been. created. Since -the additions to the reactor building will be designed to the same leaktight criteria of the original design, no change in the margin of safety defined in the Technical Specifications will occur.

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Page 4 Based-on the above analysis, the planned building extension will not introduce any unreviewed safety questions or compromise, the integrity of the reactor building, but will enhance safety aspects of spent fuel shipping.

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