ML20237G856

SER on Util 870303 & 0522 Ltr Re Optpipe Computer Code Used in Snubber Reduction Program.Code Acceptable for Piping Dynamic Analysis Using Both Uniform & Independent Support Motion Response Spectrum

ML20237G856
Person / Time
Site:	Byron
Issue date:	08/10/1987
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20237G846	List: ML20237G844 ML20237G856
References
NUDOCS 8708140222
Download: ML20237G856 (2)

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SAFETY EVALUATION REPORT BY THE OFFICE OF NUCLEAR REACTOR REGULATION VERIFICATION OF THE COMPUTER PROGRAM OPTPIPE BYRON STATION UNIT 1 DOCKET NO. 50-454

1.0 INTRODUCTION

ByletterdatedMarch3,1987,CommonwealthEdisonCompany(thelicensee) informed the staff that the piping analysis computer program OPTPIPE is currently being used in the reanalysis of selected Byron Unit 1 piping systems to justify the elimination of snubbers. To satisfy the guidelines of the NRC Standard Review Plan, Section 3.9.1 (NUREG-0800) concerning the verification of this program, the licenseg stated that the results from OPTPIPE were compared to the results of its verification as an attachment to the March 3, 1987 letter. The staff evaluated these results and concluded that there was acceptable agreement for all except one of the benchmark problems. The staff told the licensee that further application of OPTPIPE would be conditioned on the resolution of the differenc'es in results between OPTPIPE and this benchmark problem. In a letter dated May 22, 1987, the licensee informed the staff that these differences had been resolved satisfactorily.

2.0 EVALUATION In the May 22, 1987 letter, the licensee submitted the results of revised calculations for benchmark problem number 4 of NUREG/CR-1677, Vol. 2. The original calculation for this problem indicated certain unacceptable deviations from the benchmark solutions. To resolve these discrepancies, the licensee contacted the Brookhaven National Laboratory who had originated the referenced reports under contract to the NRC. As a result of these discussions it was determined that the coordinate of a certain mass point in the model had been input incorrectly, resulting in a 20-inch ,

difference in length of the piping segments attached to this mass. This 20-inch difference caused a deviation of 15% in the load acting on a support in the vicinity of the mass point. In correcting this discrepancy, the revised results indicated close agreement with the benchmark solution.

It is thus verified that the source of the deviation has been determined as being an input error and not a deficiency of the program. The corrected results now indicate that reasonable agreement has been obtained for all benchmark problems.

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3.0 CONCLUSION

The staff has verified that there is reasonable agreement between the licensee's solutions obtained by using the program OPTPIPE and the solutions to the NRC piping benchmark problems. The computer program OPTPIPE thus is' acceptable for piping dynamic analysis using both the uniform (envelope)-and the independent support motion response spectrum methods of analysis. Guidance for the application of the latter method is given in NUREG-1061, Volume 4.

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