ML19269E265

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Submits Addl Response to IE Bulletin 79-04.Seismic & Weight Load Safety Assured Per Recalculations
ML19269E265
Person / Time
Site: Pilgrim
Issue date: 05/17/1979
From: Andognini G
BOSTON EDISON CO.
To: Grier B
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
79-94, NUDOCS 7906270106
Download: ML19269E265 (2)


Text

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B O STO N EDISON C O M PANY GENERAb QFFicCs 800 BQYLETON STREET SQSTON. M Aas scNustTTm 0 2199

o. CARL ANQQGNIN8 MANAGER NUCLEAR QPERATIONS DEPARTMENT May 17, 1979 BECo. Ltr. #79- 94 Mr. Boyce H. Grier Office of Inspection and Enforcement Region I U.S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA. 19406 License No. DPR-35 Docket No. 50-293 Supplementary Response to IE Bulletin No. 79-04 Reference a) Boston Edison Company Letter to Boyce H.

Grier, dated May 1, 1979, titled " Response to IE Bulletin 79-04"

Dear Sir:

In a letter Reference a) above, Boston Edison Company indicated that more information would be submitted in regards to Item #4 of IE Bulletin 79-04.

Accordingly, the following information is effered.

In the original seismic calculations a 3" Velan Check valve weight of 64 lbs. was used instead of the correct weight of 85 lbs. For the original calculation maximum OBE seismic stresses were 81 psi in the vicinity of the valve.

Recalculated stresses, using the correct valve weight and the NRC - approved methods of Bechtel BP-f0P-1-3, give maximum OBE seismic stresses of 2,133 psi in the vicinity of the valve. The reason for the large increase in cal-culated stress (from 81 psi to 2,133 psi) resulting from the change in valve weight (from 64 lbs. to 85 lbs.) is that the original seismic calculations were performed using a detailed, accurate model of the piping system and a computer for the solution. The recalculated stresses were determined using the conservative methods of Bechtel BP-TOP-1-3, a simplified model of the piping system and a hand calculation for the solution.

The criterion of seismic acceptability is in Pilgrim FSAR Appendix A, Para-graph A.3.1.1.1. -

2133 IIS 7906270/D( G

" EiDST'ON EDISON COMPANY Mr. Boyce H. Grier May 17, 1979 Page 2

1. Primary stress + single earthquake stress <1.2 S Allowable
2. Primary stress + double earthquake stress <S Yield The pipe material is A-53 Grade B for which S Allowable = 15,000 psi and S Yield = 30,790 psi. Also Primary Stress = 3,050 psi.

Therefore, 1. 3,050 + 2,133 psi = 5,183 psi <18,000 psi

2. 3 050 + 4,266 psi = 7,316 psi <30,790 psi Also, the p'ipe is supported on a 3" sch 40 strut near the valve which can carry the extra valve weight with a large margin of safety.

We conclude that the system can safely carry all the loads imposed by weight and seismic loading.

Should you have any further questions or concerns please do not hesitate to contact us.

Very truly yours, cc: Director Office of Inspection and Enforcement Division of Reactor Opere.tions Inspection Washington, D. C. 20555 2133 116