ML17340A284

Submits Info Re Plans to Prevent ECCS Computational Errors in Response to NRC 800612 Ltr.Std Procedure Document for Steam Generator Tube Plugging Analysis Has Been Written.Qa Audits Indicated Correction of Previous Errors

ML17340A284
Person / Time
Site:	Turkey Point
Issue date:	10/14/1980
From:	Robert E. Uhrig FLORIDA POWER & LIGHT CO.
To:	Varga S Office of Nuclear Reactor Regulation
References
L-80-339, NUDOCS 8010200317
Download: ML17340A284 (6)

Text

REGULA . RY IiVFORMATION DISTR I BUT I SYSTEM (RIOS)

ACCESSION NBR:8010200317 DOC ~ DATE: 80/10/14 NOTARIZED: NO DOCKET ¹ FACIL:50-250 Turkey Point Planti Unit 3E Florida Power and Light C 0 50-251 Turkey Point Planti Unit 0i Florida Power and.Light C 500025 AUTH'AME AUTHOR AFFILIATION UHR IGt R ~ E ~ Florida Power 8 Light Co.

REC IP ~ NAME RECIPIENT AFFILIATION VARGAPS ~ AD Ooerating Reactors Branch 1 SUbJECT: Submits info re olans to prevent ECCS computational errors in response to NRC 800612 ltr.Std procedure document for steam generator tube plugging analysis has been written.QA au'dits indicated correction of previousI errors.

DISTRIBUTION CODE: ROOTS COPIES RECEIVED:LTR ENCL 'g SIZE:

TITLE: General Distrioution for after Issuance of Ooerating License NOTES:

RECIPIENT COPIES RECIPIENT COPIES, ID CODE/NA lE LTTR EN ID CODE/TVA'1E LTTR ENCL ACTION: VARGAPS ~ 04 13 1 IiVTERNAL: 0/DIRRHUM FAC08 Iit E 06 iVRC POR OR ASSESS BR

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O EG F ll 01 EXTERNAL: ACRS 09 16 1 LPDR 03 iNSI C 05 1 Ogp l tg80 TOTAL NUMBER OF COPIES REQUIRED: LTTR 38 EiVCL

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PLCRIOA POWER 4 LIGHT COMPANY October 14, 1980 L-80-339 Office of Nuclear Reactor Regulation Attention: Mr. Steven A. Varga, Chief Operating Reactors 'Branch ¹1 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D. C. 20555

Dear Mr. Yarga:

Re: Turkey Point Units 3 8 4 Docket Nos. 50-250 8 50-251 ECCS Computational Errors The purpose of this letter is to respond to your letter of June 12, 1980, which requested that we inform you of our plans to prevent ECCS computational errors in the future.

From November 1979 through May 1980 three errors were found in ECCS ana'lyses performed for Turkey Point Units 3 and 4. Each event was reported to the NRC in accordance with Technical Specification 6.9.2 (Reportable Occurrences}.

Because of this relatively short history of errors, Florida Power 5 Light Company requested that the NSSS vendor provide assurance that the present analysis had been performed correctly and that future analyses would not encounter similar problems.

In response to our request, the NSSS vendor has again verified the input data to the Turkey Point LOCA analysis, and taken other measures to ensure that the present LOCA analysis furnished to FPL contains no errors and is consistent with approved models. Additional corrective action taken or planned by the NSSS vendor as a result of computational errors are as follows:

(1) With respect to the pressure drop input to the steam generator tube plugging analysis, a standard procedure document for steam generator tube plugging analysis has been written. Other existing standard procedure documents dealing with SATAN pressure drops have been revised to include a cautionary statement to insure proper consideration of the impact of data changes.

(2) With respect to the reactor vessel upper head modeling input to the SATAN code, the standard procedure document for reactor vessel upper head modeling was clarified to guard against use of inappropriate modeling assumptions. In addition, an automated cross check of input data with data for a similar plant is now required in order to identify potential discrepancies. For future ECCS efforts, analysts will be provided with a base plant-specific input deck from an 0 automated generator/processor system. This system wil 1 create the 4, w plant input deck from a permanent library of data which has been verified and documented. This feature will provide an additional 801020 OGIP

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Office of Nuclear Reactor Regulation Attention: Mr. Steven A. Varga, Chief Page Two element of confidence that the analysis efforts are being performed consistently and correctly.

(3) With respect to the use of a clad heatup rate dependent burst curve in the large break model, the NSSS.vendor has demonstrated that proposed improvements in the Westinghouse evaluation model would compensate for the penalties associated with clad heatup rate dependence and the fuel rod models proposed by the NRC in draft NUREG-0630.

In future evaluation model changes, the effect on clad heatup rate will be checked along with other sensitive parameters, and appropriate model changes will be made when necessary.

To obtain further assurance of the correctness of the vendor ECCS analysis, FPL has performed two guality Assurance (gA) Audits of the Westinghouse ECCS Safeguards Engineering Group in 1980. The first one which took place on March 4-5 at Monroeville, Pa.. resulted in a recommendation to cross check the results of the Turkey Point LOCA computer deck against the results of the standard loop deck. The error, which was reported to the Region II Office of Inspection and Enforcement on May 27, 1980, was found after this cross check had been performed.

The second audit of the Westinghouse ECCS Group was performed by FPL personnel from the gA and Nuclear Analysis Departments on September 3-5, 1980 at Monroeville, Pa. Present and proposed future methods, procedures and standards used by the ECCS Group for assuring the validity of the ECCS analysis were reviewed., The auditors examined in detail a number of input parameters and traced back the origin of these input values. It was concluded that Westinghouse had indeed corrected previous errors and improved their methods and procedures, and that the occurrence of input errors, such as had been found during the last year, was highly unlikely in the future.

In summary, both FPL and the NSSS vendor are concerned about ensuring the adequacy of ECCS analysis results. The steps described above have been taken with this goal in mind and should serve to prevent ECCS computational error in the futur e.

Very truly yours,

. Robert E. Uhrig Vice President Advanced Systems & Technology REU/MAS/ras cc: Mr. D. P. O'Reilly, Region I!

Harold F. Reis, Esquire

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