ML20086S194

Requests Exemption from GDC 4 Per Generic Ltr 84-04,based on Net Safety Increase of Plant Design by Application of Alternate Pipe Break Criteria.Overall Plant Benefits Would Include Reduced Piping Heat Loss

ML20086S194
Person / Time
Site:	Beaver Valley
Issue date:	02/24/1984
From:	Woolever E DUQUESNE LIGHT CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
2NRC-4-017, 2NRC-4-17, GL-84-04, GL-84-4, NUDOCS 8403010416
Download: ML20086S194 (3)

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e 2NRC-4-017 (412) 787 - 5141 Telecopy Nuclear Construction Division February 24, 1984 Robinson Plaza, Building 2, Suite 210 Pittsburgh, PA 15205 Mr. Harold R. Denton, Director Office of Nuclear Reactor Reguistions Nuclear Regulatory Commission Wanihington, D.C.

20055 BEAVER VALLEY POWER STATION - UNIT #2 DOCKET N0. 50-412 ALTERNATE PIPE BREAK DESIGN CONSIDERATION

Reference:

Generic Letter 84-04

Dear Mr. Denton:

Duquesne Light Company has followed with interest the recent activities of the Nuclear Regulatory. Commission and the nuclear industry on the' gcueral topic of alternate pipe break design basis.

We note that the positive intent to modify the existing criteria for Staff has expressed a considering uouble-ended pipe. breaks in the Reactor Coolant Primary Loop piping for Westinghouse supplied nuclear steam supply systems such t.)

the type utilized at the Beaver Valley Power' Station.

Duquesne Light Cenpany fully expects the work that Westinghause has done in developing the mechanistic fracture analysis concept for Reactor Coolant Primary Loop piping will be applicable to BVPS-2 to eliminate the doubled-ended ruptures now postulated.

In addition, we expect this work will eventually carry over into 'other plant systems and will eliminate double-ended breaks in these systems by empiv;ing the mechanistic. fracture analysis.

Duquesne Light Company is interested in applying the results of this work in BVPS-2 at the earliest opportunitv. On addition to relieving congestion ~ ccused by the pipe whip restraints and jet deflectors which result f rom. application of the present criteria) it will be particularly beneficial at Beaver Valley Unit #2 in elimina' ting design, material and erection costs associated with these restraints and ~ jet deflectors, many of which are yet to be designed, procured, or installed.

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Mr.i Hsrold R..Dinton.

Nuclear-Regulatory Consnission

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PageL2.

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.m It is our ' opinion that no rule-making. is necessary to implement l these 1 criteria changes; however, we note that the Commission does intend to

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proceed ~ with' a rulemaking to medify GLC-4 to permit the -elimination of the pipe i. whip restraints. We rcquest an exemption to GDC-4 " based upon a net

!saf ety.- increase of _ the $ ant design by application of - the alternate. pipe

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break criteria. This net safety increase includes:

iA. Lower occupational - exposures for primary loop inspections due tc, elimination of the removal / installation requirements.

'B.,1 Lower risk of pipe / restraint interaction due to either improper installatior. or misalignment.

Specifically,' we propose ' that the following revisions 1be

'incorpo. rated into the BVPS-2 licensing basis:

A.

Elimination ~ oi double-ended' breaks in the Reactor Coolant Primary Loop. by _ use : of _ the. mechanistic fracture analysis

- concept -- in ; accordance.with. the criteria -established in the referenced'NRC letter-dated February 1, 1984 (84-04).

1B.

Elimination of 'all' arbitrarily. selected. intermediate pipe breaks 'now. postulated, although otherwise' meeting _ defined stress criteria.

4 C.. Elimination. of the dout.le-ended ! breaks for Reactor Coolant

- Primary (Loop. and for #:hcr high energy piping < systems will also

. eliminate -consideration of the following:

1.

Local pipe whip. and reaction ' forces

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2. -Jet impingement effects 1

3.

Reactor. cavity ' and subcompartment pressurization, including asynunetric loadings.

L4.

Hydro-Dynamic loads in. Feactor Coolant Primary. loop and other" high j energy piping produced by these' double-ended breaks q

If thne changes._ are implemented, BVPS-2 would significantly lower

- its ' total man-rem 'of. occupational, radiation exposure over the life of the-

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unit' - -in performing imaintenance: and. inservice- = inspection activities.

' Additionally, foyerall: plant: benefits' would-include improved access _for

. operation f and maintenance, and reduced piping heat 11oss to containment which resultsf from uninsulated portions ~ of ' niping'_ at ' whip' restraints.

In addition, of - unanticipated pipe. restraint

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for thermal growth and W

Lthe i reduc'ed '. risk seismic' movementfwould add ' to rather than detract ' from plant safety.

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,x Ar. H:roli'R.-Denton

_ Nuclear-Regulatory Commission Page 3 We estimate that several million dollars would be saved by a timely application 'of.this concept and recer.mendat ions to Beaver Valley Unit #2.

2 These savings - would be realized _ in the areas of design, procurement, and installation activities associated with the pipe whip restraints and jet impingement. shields that would be elimisated using the mechanistic fracture

, analysis concept.

In order to -achieve the. maxiemum advantage fro.n this new *.echnical.

basis,

.we. request a. decision on cur-proposal by April 1,1984. To achieve this-.' time ty. resolution, we suggest that a - meeting with the Staff may be appropriate to resolve suy outstanding - issues or to obtain any further guidance.necessary to _ expedite a final resolution on this matter. A separate

- submittal containing the detailed fracture mechanics results for the primary loop will be providcd to the NRC by May 30, 1984.

Very truly yours, E. J. Woolever Vice Presidcnc Nuclear Construction Division

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JAH:e1

.cc:

D. Eisenhut-L. Lazo G. Knighton.

G.'Walton NCD File.

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