ML20214G503
| ML20214G503 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 02/24/1976 |
| From: | Renberger D WASHINGTON PUBLIC POWER SUPPLY SYSTEM |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| Shared Package | |
| ML20214G496 | List: |
| References | |
| CON-WNP-0014, CON-WNP-14 GO2-76-65, NUDOCS 8605220237 | |
| Download: ML20214G503 (2) | |
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Washington Public Pcwer Supply Si em A JOINT OPERATING AGENCY b)
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..s s a e o~a so.,.4..i.ii February 24, 1976 G02-76-65 Docket No. 50-397 Mr. R. H. Engelken, Director Nuclear Regulatory Commission, Region V Suite 202, Walnut Creek Plaza 1990 N. California Boulevard Walnut Creek, California 94596
Subject:
WPPSS NUCLEAR PROJECT NO. 2 MARK II CONTAINMENT - DESIGN DEFICIENCY _
References:
- 1) Letter, W.R. Butler to J.J. Stein, dated April 17, 1975, " Suppression Pool Hydrodynamic Loads During LOCA'
- 2) Letter, W.R. Butler to J.J. Stein, dated April 23, 1975, " Pool Dynamic Load Due to Relief Valve Operation"
- 3) Letter, N.0. Strand to 0.0. Parr, dated November 10,1975 (G02-75-310)
" Mark II Containment Program"
Dear Mr. Engelken:
The purpose of this letter is to inform the Nuclear Regulatory Commission of an apparent design deficiency which we believe to be reportable under 10 CFR 50.55e. We have been preparing a plant-unique design evaluation report in response to NRC-Division of Reactor Licensing letters of April 17 and 23,1975 (References 1 and 2) which request additional information on suppression pool containment loads due to relief valve discharges and loss of coolant accidents. A program for supplying the requested information was developed in conjunction with other Mark II Containment Owners, their architect-engineers, and General Electric.
A Mark II Containment Dynamic Forcing Functions Information Report (NE00-21061 and NEDE-21061P) (Reference 3) was prepared as a phenomena description document which is being used to evaluate the Mark II Containment for the WPPSS Nuclear Project No. 2.
As you are aware, the WPPSS Nuclear Project No. 2 containment is an ASME-Section III free-standing steel containment. Results of the design assessment are not complete but preliminary results indicate a resonance phenomenon exists (during safety relief valve actuations) due to a couple be-tween the suppression pool and the metal shell.
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4 hr. R.H. Fogelken February Page 2 G02-76-75 Based on our review of the preliminary results from Burns and Roe, we have concluded the completed WPpSS Nuclear Projcct No. 2 Containment should be modified due to the resonance situation. The need for modification is based on conservative forcing function assumptions available at this time. We believe this modification falls under the reporting requirements of 10 CFR 50.55e.
Our Architect-Engineer, Burns and Roe, has identified a design modification concept that would allow the construction to continue on the remainder of the plant without precluding the ability to correct the existing deficiency.
The concept involves adding stiffening to the interior of the wetwell.
Since this deficiency is involved in a broad Mark II containment re-evaluation being performed for the NRC Division of Reactor Licensing, we plan to continue to resolve the issue through the Division of Reactor Licensing. We will copy your office on our correspondence and reports regarding this deficiency.
We hope this arrangement will be satisfactory to you as it will reduce the complexity of the resolution of this matter.
Very truly yours, M
D. L. RENBERGER Assistant Director Generation and Technology DLR:GLG: cab cc: Director of Nuclear Reactor Regulations Attention: Dr. W.D. Butler, Chief Light Water Reactors Projects Branch 1-2 U.S. Nuclear Regulatory Commission Washington, D.C.
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