ML20244A465

Application for Amend to License DPR-66,changing Tec Spec 3.2.3 Re Nuclear Enthalpy Hot Channel Factor,Tech Spec 4.2.2.2 Re Radial Peaking Factor & Removing Imposition of Rod Bow Linear Power Penalty for Region Average Burnups

ML20244A465
Person / Time
Site:	Beaver Valley
Issue date:	09/22/1978
From:	Dunn C DUQUESNE LIGHT CO.
To:	Schwencer A Office of Nuclear Reactor Regulation
Shared Package
ML20236X976	List: ML20236X973 ML20244A465
References
TAC-10837, NUDOCS 7810020122
Download: ML20244A465 (5)

Text

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'Af (412) 471 4 300 435 Sixth Avenue Pittsburgh, Pennsylvania 15219 September 22, 1978 Director of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Attention: A. Schwencer, Chief Branch No. 1 Division of Operating Reactors Washington, D. C. 20555

Reference:

Beaver Valley Power Station, Unit No. 1 Docket No. 50-334 Request for Amendment to Operating License Gentlemen:

Enclosed are three (3) signed originals and thirty-seven (37) copies of requested changes to the Appendix A Technical Specifications portion of the Beaver Valley Power Station Operating License.

This request involves a change to Technical Specification 3.2.3 (Nuclear Enthalpy Hot Channel Factor - F$H); Technical Specification 4.2.2.2 (Radial Peaking Factor - Fxy), and a request to remove the possible imposition of a rod bow linear power penalty for region average burnups greater than 24,000 MWD /MTU. (Reference Amendment No. 9 to the BVPS Operating License dated July 12, 1977.)

The purpose of these requested changes is to:

(a) RelaxtheexistingpenaltyonFfHasimposedinAmendmentNo.10 to the station Technical Specifications dated July 27, 1977 and (b) x to values that vary with core elevation RaisethelimitonF[htoassurethattheallowablevalueof and that are low enou Fq(Z) is not exceeded, but are high enough to preclude unnecessary restrictions on core power levels that are predicted to be required during future fuel cycles with the existing limit (c) Clarify that rod bow linear power penalties are not required during any future fuel cycles on the Beaver Valley No. 1 Unit.

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Beaver Valley Power Station, Unit No. 1 Docket No. 50-334 Request for Amendinent to Operating License Page l Safety Evaluation F Westinghouse proprietary submittals to the NRC staff AH NE-CE-1580 and NS-CE-1598 in October, 1977 provide the results of additional DNB experiments and in-plant measurement data. These results indicate that the gross DNBR penalty for Beaver Valley Unit No.1 is significantly less than originally predicted, reaching a maximum of 10.6% DNBR.

Most of this penalty can be offset by identified margin in the FSAR analysis of 9.1% DNBR. This results in a residual penalty of up to 1.5% DNBR which is accounted for by the proposed 1% penalty on FAH*

Fq (Z) The closure correlation used to predict rod bowing as a function of burnup has been updated as a result of a separate Westinghouse submittal to the NRC staff -

NS-TMA-1760 dated April 19, 1978. This revision allows elimination of the need for any penalty on Fg T until region burnups of 28,000 MWD /MTU are achieved. Using the revised correlation F qT penalties are not imposed until region average burnups exceed 60,000 MWD /MTU.

This region average burnup would not be encountered during a normal cycling scheme and, thus, consideration of FqT restrictions due to rod bowing can be eliminated.

F The elevation-dependent peaking factor, F 9(Z), is the

• Y primary power distribution parameter limited in the Technical Specifications for LOCA protection. Both the radial and axial power distributions are factors in determining the peaking factor. Discussion of the methods used to calculate F q(Z) is provided in WCAP-8305,

" Power Distribution Control and Load Following Procedures" (Westinghouse Proprietary, September, 1974).

The radial power distributions are relatively fixed and are bounded by upper limits, while axial power distributions are controlled by well-defined procedures outlined in the Technical Specifications. One component of F 0 (Z) is the radial peaking factor Fxy(Z), which is defined as the ratio of peak power density to average power density in the I horizontal plane at elevation Z. For Cycle 1, with all fresh fuel at BOL, Fxy(Z) is a monotonically varying function of elevation due primarily to an elevation-dependent moderator density feedback. In a reload core, the variation of Fxy(Z) with elevation is more complex reflecting a composite of burned and fresh fuel axial power shapes. In the central portion of the core (axially),

Fxy(Z) is located in the fresh fuel region, and at BOL, I

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4 Beaver Valley Power Station, Unit No. 1 Docket No. 50-334 Request for Amendment to Operating License Page F is calculated to.be higher than in Cycle 1, resulting in

[7 't) the proposed change to Technical Specification Page 3/4 2-6a.

.The reload core, however, exhibits flatter axial shapes, which ensures that Fq (Z) remains within allowable limits.

The axial' power shapes during power operation are strongly dependent on power history during the cycle. To determine bounding values of the peaking factor Fq x (relative power) )

was calculated as a function of elevation by assuming  !

various load follow transients on the reactor through '

insertion and removal of control rod Banks C and D and considering the effects of the accompanying variation in axial xenon and power distributions, as described in WCAP-8385. Beginning and end of cycle conditions were included in the calculations, and several different histories of operation were assumed in calculating the effects of load follow transients on the axial power distribution.

The maximum calculated values of Fq x (relative power) were determined at various elevations in the core using the requested allowable maximum values of Fxy at that elevation. The calculated values in all cases were determined to be below the nuclear design operating envelope of 2.32 times K(Z), where K(Z) is the normalized Fq(Z) function shown on Figure 3.2-2 of the Technical Specifications. Calculations that were performed for end of cycle 1 conditions with the proposed revisions to the Fxy(Z) Technical Specification limits similarly showed that operating envelope was satisfied for Cycle 1.

Evaluations also indicate that the proposed Fxy(Z) change will not cause the Fq(Z) Technical Specification limits to be exceeded in subsequent reload cycles. The F q (Z) limit envelope will be verified by detailed calculations for each reload design. That is, the proposed Technical Specification Fxy(Z) limits are not restricted to operation through Cycle 2, since they will be demonstrated to be met for each subsequent cycle of operation.

Attached are proposed changes to Appendix A Technical Specifications which implement-the previously described amendments.

l Also enclosed is a check in the amount of $12,300.00 for this Class IV change in accordance with 10CFR 170.22.

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s i Beaver Valley Power Station, Unit No. 1 l

Docket No. 50-334 Request for Amendment to Operating License

! Page We understand that similar requests have been previously approved on the Trojan Nuclear Plant docket and would appreciate review and approval of these changes prior to March, 1979, the scheduled shutdown date for the first refueling

of Beaver Valley Unit No. 1.

Very truly yours, C. N. Dunn Vice President, Operations Attachment l

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(COPPORATE SEAL)

Attest:

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H . W . 'S taa s Secretary COMMONWEALTH OF PENNSYLVANIA)

) SS:

COUNTY OF ALLEGHEITI )

On this , 22 # day o f M/'rJN #c /C- , 1978, before me, DONALD W. SHANNON , a Notary Public in and for said Commonwealth and County, personally appeared C. N. Dunn, who being duly sworn, deposed, and said that (1) he is Vice President of Duquesne Light, (2) he is duly authorized to execute and file the foregoing Sub-mittal on behalf of said Company, and (3) the statements set forth in the Submittal are true and correct to the best of his knowledge, information and belief.

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DONALD W. SHANNON, Notary Public fittsburgh, Allegheny Co., Pa.

My Commission bpires June 7,1979 O

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