L-87-336, Advises That Westinghouse Has Informed Util of Input Error Where Three high-head Safety Injection Pumps Assumed in Large Break LOCA Analysis.Licensee Evaluating Design Changes to Mitigate Increases in Peak Clad Temps

Advises That Westinghouse Has Informed Util of Input Error Where Three high-head Safety Injection Pumps Assumed in Large Break LOCA Analysis.Licensee Evaluating Design Changes to Mitigate Increases in Peak Clad Temps

ML17342A869
Person / Time
Site:	Turkey Point
Issue date:	08/20/1987
From:	Woody C FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
L-87-336, NUDOCS 8708240286
Download: ML17342A869 (8)

Text

ACCESSIPN NBR:

FAC IL: 50-250 50-251 AUTH. NAME WOOD Ye C. O.

RECIP. NAME REGULATORY ORMATION DISTRIBUTION SY (RIDS) 8708240286 DOC. DATE: 87/08/20 NOTARIZED:

NO DOCKET 0 Turkey Point Planti Unit 3i Florida Power and Light C

05000250 Turkey Point Planti Unit 4i Florida Power and Light C

05000251 AUTHOR AFFILIATION Florida Power 8c Light Co.

RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Advises that Westinghouse has informed util of input error where three high-head safety ingection pumps assumed in large break LOCA analysis. Licensee evaluating design changes to mitigate increases in peak clad temps.

DISTRIBUTION CODE A001D COPIES RECEIVED: LTR

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EQ8cQ BRUSKEi 8 NRC PDR 01 NRR/DEST/ADS NRR/DEST/MTB NRR/DOEA/TSB OQC/HDS2 RES/DE/EIB LPDR NSIC TOTAL NUMBER OF COPIES REQUIRED:

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L-87-336 U. S. Nuclear Regulatory Commission

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Document Control Desk Washington, D. C. 20555 Gent lemen:

Re:

Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-25 I Lar e Break LOCA Anal sis By letter L-85-l57 dated April l6, l985, Florida Power Bc Light Company (FPL) reported a calculated peak clad temperature (PCT) of 205I F in the event of a worst case large break LOCA transient.

The calculation was found acceptable by the NRC in a safety evaluation issued on May l4, l985.

FPL has now completed its review of a recent Westinghouse evaluation of subsequent PCT changes resulting from non-conservatisms identified during the Turkey Point Plant design basis reconstitution effort.

In accordance with 10 CFR 50, Appendix K, II.I, these changes are hereby reported.

Westinghouse has informed FPL of an input error where three high-head safety injection pumps had been assumed in the analysis instead of two.

The corrected use of two pumps increased the PCT by 9 F to 2060 F. This change was reported to the NRC as Licensee Event Report (LER) 250-85-033.

While reviewing the design basis of the Emergency Core Cooling System (ECCS), a non-conservatism in the assumed containment spray flow rate was discovered.

The analysis assumes a containment spray flow of 2900 gpm corresponding to a containment pressure of 60 psig.

In actuality, the spray flow rate may increase to 3643 gpm while the containment pressure is nearly 0 psig in the beginning of the transient.

This would cause additional heat removal from the containment, lower containment pressure, higher break flow and higher peak clad temperature.

This non-conservatism was reported to the NRC as LER 250-87-l4.

Westinghouse has estimated a PCT increase of l5 F to a total of 2075 F due to the increased containment spray flow.

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U. S. Nuclear Regulatory Commission L 336 Page two Another non-conservatism was discovered relating to the low head safety injection pump flow rates assumed in the accident analysis; a minimum of 3600 gpm during the injection phase, and a maximum flow limit of 3750 gpm because of NPSH requirements during post-accident recirculation from the containment sump.

These current upper and lower flow rate limitations do not provide a large enough band to allow the low head safety injection flow rate to be set with the required precision assuming the instrument inaccuracies associated with the instrumentation used to measure the pump flow.

To broaden the

band, the minimum flow rate 'was reduced to 3400 gpm.

This reduced analysis flow value would result in an increase in PCT of 32 F, resulting in a revised PCT of 2 I 07 F.

The revised PCT of 2I07 F for the worst case large break LOCA transient correcting for the effects discussed herein is below the limitof 2200 F as per the acceptance criteria in IO CFR 50.46.

FPL is evaluating design changes to mitigate the increases in PCT.

If there are any questions, please call us.

Very truly yours, C. O. W Group Vice President Nuclear Energy COW/TCG/gp cc:

Dr. J. Nelson Grace, Regional Administrator, Region II, USNRC Mr. D. R. Brewer, USNRC Senior Resident Inspector, Turkey Point Plant TCG6/042/2

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August 19, 1987 iTR IBUTION Docket file w/o encl+

PD22 Reading w/o encl.

D. Miller w/encl.

D. McDonald w/encl.'OCKET NO(S). 50-250 and 50-251 Mre C. 0. Moody Group Vice President Nucleaf Energy Florida Power and Light Company Post Office Box 14000 Juno Beach, Florida 33408

SUBJECT:

TURKEY POINT UNITS 3 AND 4 The following documents concerning our'eview of the subject facility are transmitted for your information.

Notice of Receipt of Application, dated Draft/Final Environmental Statement, dated Notice of Availability of Draft/Final Environmental Statement, dated Safety Evaluation Report, or Supplement No.

dated Environmental Assessment and Finding of No Significant Impact, dated Notice of Consideration of Issuance of Facility Operating License or Amendment to Facility Operating License, dated Q Bi-Meekly Notice; Applications and Amendments to Operating Licenses Involving No Significant Hazards Considerations, dated 8/12/87

[see page(s)]

Exemption, dated Construction Permit No.

CPPR-

, Amendment No.

da'ted Facility Operating License No.,

Amendment No.

dated Or'der Extending Construction Completion Date, dated Monthly Operating Report for transmitted by letter dated Q Annual/Semi-Annual Report-transmitted by letter dated 4

Enclosures:

As stated cc: See next, page Division of Reactor Projects-I/II Office of Nuclear Reactor Regulation oFFlcEII SURNAME)

DATEt/I L

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NRC FORM 318 110/80) NRCM 0240 OFFICIAL RECORD COPY

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