ML17037C337

Letter Enclosing Change Request No. 2 Requesting a Modification to the Safety Limit on Fuel Cladding Integrity and Advising That the Change Has Been Reviewed and Bears the Approval of the Station Operations Review Committee ...

ML17037C337
Person / Time
Site:	Nine Mile Point
Issue date:	12/09/1969
From:	Pratt M Niagara Mohawk Power Corp
To:	Morris P US Atomic Energy Commission (AEC)
References
Download: ML17037C337 (12)

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ENCLOSURESI CHAI"E HWUE8P NO. 2 to Tech S ecs Rega2atory AEC PDR fil requesting mc@ifications to safety Compliance 2) limit on fue1 cleMlina, integrity. OGC amP O6A H Price k Skovholt Duhe/Ievtne si ed. 5 1 conf'd. c s recsd) D Tho so REMARKS(

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NIAGARA MOHAWK POWER CORPORATION NIAGARA ~~ MOHAWK 300 ERIE BOUI EVARO WEST SYRACUSE, N, Y. 13202 December 9, 1969 Dr; Peter A. Morris, Director Division of Reactor Licensing United States Atomic Energy Commission Washington, D. C. 20545

Dear Dr. Morris:

Re: Change Request No. 2 Provisional Operating License DPR-17 Docket 50-220 Enclosed are three signed copies and nineteen reproduced signature copies of Change Request No. 2 requesting a modification to the safety limit on fuel cladding integrity.

In accordance with Technical Specification requirement

6. 1. C. 2, this change has been reviewed by the Station Operations Review Committee and the Safety Review and Audit Board, respec-tively, and bears the approval of both bodies.

We ask that the Commission give prompt consideration to this request for change.

Very truly yours H. Pra t Vice President and Executive Engineer

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Kl',/PP, CRINGE RE VEST NO. 2 PROVISIONAL OPERATING LICENSE DPR-17 Qygg~gf (DOCKET g) gyj 50-220)

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.Specification (Appendix A of the above captioned license) as follows:

1. S ecification To Be Changed Safety Limit - Fuel Cladding Integrity, Figure 2.1.1 and Specification 2.1.1.b

2. Extent of Chan e

a. Figure 2.1.1 - Extend the 1250 psia and 1015 psia safety limit curves from 20 percent recirculation flow to 5 percent recirculation flow.

b. Specification 2.l.l.b - h1odify specification to permit reactor operation in accordance with the additional data that is applicable from 5 percent to 20 percent recircu-lation flow as shown on the attached figure.

3. Chan e Re uested

a. Figure 2.1.1 - Supersede the existing Technical Specification Figure 2.1.1 with the attached figure.

b. Specification 2.l.l.b - ftodify statement to read: "When the reactor pressure is less than 585 psig or reactor recirculation flow is less than 5 percent of design, the reactor thermal power shall not exceed 307 h/Wt."

c. References, Page 8 - Add Reference (6) Change Request No. 2 - Discussion.

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4. Discussion The extension of the fuel cladding integrity safety limit curves, Figure 2.1.1, to flows as low as ".percent of design was performed using the same assumptions and initial conditions

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as were employed i.n the curves presently in the Technical Speci-fications. The design basis critical heat flux correlation given in APED-3892 was used. The power shape was based on a MCHFR of 1.5 at 120 percent over power,and results in a total peaking factor of 3.13. Maximum feedwater ter;perature was assumed for the various pressures and flows and the core inlet enthalpy was based on the subcooling res<<lt~ng from equilibrium operation. ( E Evaluation of the fuel cladding integrity safety limit in the low flow region was performed using the design basis criti-cal heat flux correlation at the low mass -'low limit. This evaluation is conservative due to the inverse relationship between mass flow and critical heat flux in the high quality region of the correlation. Cri.tical heat flux for mass flows lower than the low limit of the design basis critical heat flux correlation are greater tha'n that predicted by the corre-lation.

The proposed change of Safety Limit ".l.l.b and Figure 2.1.1 does not reduce the. margin ot'afety limit protection since neutron monitoring system rod block and scram trips main-tain adequate margin to proposed safety limit lines on Figure E. Janssen and S. Levy, "Burnout Limit Curves for Boiling Water Reactors" APED-3892, April 1, 1962.

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4. Discussion (Continued) for all regions of possible operation. The core natural circu-lation characteristic, the lower limit of core flow for power operation, precludes operation up to the safety limit without having first reached the rod block trip and the scram trip.

Prior submittal to the FDSAR, Appendix E, has shown that the reactor is adequately protected by the 'pressure scram and fixed 120 percent flux scram for all transients considered such as the continuous rod withdrawal and turbine trip without bypass originating from all normal operating .conditions includ-'ng the low power and flow levels consistent >>ith natural circulation.

NIAGARA M01(NOK P()I('ER. CORPORATION by pinot fl. Pratt Vice President Executive Engineer

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FIGURE 2.1.1 FUEL CLADDING INTEGRITY SAFETY LIMIT 160 NOTES I. Rated power is l538 Mwt 1000 PSIG 140

2. Design flow is 67.5 x IO Ib/hr

3. Total peaking factor is <3.13

4. Core pressure is >585 psig 1235 PSIG

5. Water level shall not be more than I'-7 II/16" below min.

120 normal level (El. 302'-9").

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