ML19208B573

Technical Evaluation Rept, Deletion of Reactor Trip on Turbine Trip Below 50% Power.

ML19208B573
Person / Time
Site:	Farley
Issue date:	08/01/1979
From:	Reeves W LAWRENCE LIVERMORE NATIONAL LABORATORY
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ML19208B570	List: ML19208B573
References
NUDOCS 7909210024
Download: ML19208B573 (3)

Text

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TECHNICAL EVALUATION REPORT JOSEPH M. FARLEY NUCLEAR P0hTR PLANT DELETION OF REACTOR TRIP ON TURBINE TRIP BELOW 50 PERCENT POWER DOCKET NUMBER 50-348 AUGUST 1979 PREPARED BY WAYNE E. REEVES LAh"itENCE LIVERMORE LABORATORY

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1.0 INTRODUCTION

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The Alabama Power Co., the holder of License #NPF-2 at the' Joseph M. Farley Nuclear Plant, submitted a license amendment request for the Geletion of  ;

reactor tria on turbine trip below 50% power. Their present criteria , _,

states that they will trip the reactor any time the power turbine trip when they are operating above 10% of rater pever.

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2.0 PROPOSED CHANGE

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Pursuant to 10CFR50.59, the holders of Operating License INFP-2 propose the following changes to Appendix A Technical Specifications.

1. Add to Table 3.3-1 the f ollowing: -

"P With 2 of 4 power range neutron flux channels > 50% of rated thermal power, P-9 defeats the automatic bl6ck of reactor trip on turbine trip."

2. Add on limiting safety system settings B2-7 which reads, -

" Turbine Trip A Turbine Trip causes a direct reactor trip when operating above P-9. Each of the turbine trips provide iurbine protection and '

reduce the severity of the ensuing transient. No credit was taken in the accident analyses for operation of these trips. Their functional capability at the specififed trip settings is required to enhance the overall reliability of the Reactor Protection System."

3.0 REASON FOR CHANGE: '

The submittal states:

The current Farley reactor protection systes designed provides for '

a direct reactor trip following a turbine trip shen the plant is aheva 10 percent power. Since Farley is designed for 50 percent load rejection capability, a reactor trip following turbine trip below 50% power can be eliminated without compromising adequate safety margies. Del,etion of the reactor trip following turbine trip would significantly . reduce the down ti=e required if the cause of the turbine trip is readily correctable.

4.0 REVIEW OF LICENSEE'S SUEMITTAL:

The review showed:

1. The licensee states that, "The plant operaticns review cce=1ttee and the Nuclear Operations Review Board have reviewed the above proposed changes and have determined that the changes do not involve an unreviewed safety question."

2. An evaluation and analysis has been performed to ensure that the dele-tion of reactor trip following turbine trip from 50 percent power or less has no adverse affect on plant safety. This evaluation consisted of:

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-1 (1) A verification of the worst case transient wTch iespect to cere limi?.s in the 10 to 50 percent power range is accep:able

'(1.e., ricl=23 DNER > 1.30), -

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(2) The.gonaileration of the worst single active failure (unsuccessful

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reactor coolaat pump bus transfer 30 seconds after turbine trip),

acd (3) The. acceptability of potential offsite doses resulting from

, the-loso of the condenser and consequential atmosphtric dumping o* steam through thi main stes:a lins safety valve.

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Results of the analysis show that the plant design is auch that a

- turbina trip without a direct or immediate reactor trip from 50 per-cent power or less presents no hazard to the integrity of the RCS, the main steam system, or the general public. Pressure relieving devices incorporsted in the rwo systems are adequate to limit the

, - maximum pressuras to vithin the design limits. The anniysis also

- demonstrates that for a complete loss of forcod . reactor coolant flow initiated from the most adverse preconditions of a turbine trip, the DNBR is well above 1.3 et any_ time during the transient, Thus, no

- fuel or clad damage is predicted, and all applicable acceptance criteria are mat. In addition, the potential offsite doses associated with the loss of che condenser and consequential atmospheric damping'of steam through the main steam safety ~ralves were.found to ba well within the

• Appendix I limits.

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5.0 U CONCLU,SIONS:

I have reviewed the technical aspects of the licensee's submittal which shows:

1. No degradation of the engineered safety features occurs due to this changee The system has the capability to bypess 50% of rated power steam around

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the turbine.

3. No credit is taken for the steam dump system in the FSAR.

Based on this review, I recommend that NRC approve this proposed change.

6.0 REFERENCES

1. Letter, F. L. Clayton, Jr., of Alabama Power to A. Schwencer of DOR, November 15, 1978. ,

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2. FSAR Section 15.2.7.

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3. Enclosed sub ittal l

a. Safety Evaluation of Reactor Trip Following Turbine Trip Sslow 50% Power.

b. Technical Specification Table 3.3-1

c. Limiting Safety System Settings B2-7 L

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