ML19322D335
| ML19322D335 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 12/28/1976 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| Shared Package | |
| ML19322D327 | List: |
| References | |
| FOIA-79-416 NUDOCS 8002110491 | |
| Download: ML19322D335 (2) | |
Text
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WA5mNGTON D. C. 20555 g., N S W
- i Mc g './ ** o,8 Decembdr 28, 1976
~e MEMORNIDUM FOR:
Boyce H. Grier, Dir., RIP, IE FROM:
Karl V. Seyfrit, Chief, RTA, RIP
SUBJECT:
ALLEGATIONS OF DEFECTIVE WELDING IN THE SURRY NEUTRON SHIELD TANKS In y memorandum of December 16, 1976 to you concerning this subject, an assessment of the safety significance which might result from
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alleged welding defects was presented.
This assessment was based on information obtained from the Surry Units 1 and 2 FSAR, and related to the shielding and cooling functions of the neutron shield tank.
Con-tinued review of this matter reveals that the shield tan!: also pro-vides the support for the reactor vessel.
This latter function was not immediately evident from the initial review.
While the support function was not considered in y earlier memo, the conclusions as stated there remain valid.
The basis for this conclusion with regard to the support-function is that normal loading result,pri-marily in compressive loads on the welds.
Further, to significantly affect the load bearing capability of the structure, there would need to be gross weld failures.
Such failures would likely initiate as leaks, which as discussed in y earlier memo, would be readily detected in the early stages of weld failure, affording ample time for reactor shutdown, analysis, and repair of the weld.
l As you know, NRR is currently evaluating the effects of asymetric loadings on reactor vessel supports under LOCA plus seismic loading conditions.
These combined loadings @ ions' would result in loadings other than com-make the weld integrity a more important factor, since such condit pressive.
On the other hand, analysis of the asymetric loadings may result in support modifications which nould reduce reliance on the welds in question even further.
It should oe noted that the probability of
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December 28, 1976 either a LOCA or a design basis seismic event is quite low.
The_ combi-nation of these events, although they are not independent, would of~
course be even lower.
For this reason. NRR is content to. permit continued op'eration_of PWRs while the asynne.tric_Loadina analys,is cpntinnne this hnilysis has been discussed with appropriate NRR pEriannal who agree with o
'i.he stateaJosjJ. ton A question related to these allegations of poor welds in the shield tcnks has been raised regarding whether or not there may be general problems with weld quality at Surry Units 1 and 2.
You may recall that there were numerous welding difficiencies found during construction of these units. This led.to increased attention to welding practices and auamented inspections in these areas.
Based on these acticns, there is presently no reason to believe that substandard welding is present in the piping systems at Surry Units 1 and 2.
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'f, 41 A.jj Karl V. Seyfrit, Chief Reactor Technical Assir.tance Branch e
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