ML19345G377
| ML19345G377 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 07/02/1973 |
| From: | Stello V US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Deyoung R US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML19345G365 | List: |
| References | |
| ZECH, NUDOCS 8104070116 | |
| Download: ML19345G377 (1) | |
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UNITED STATb5
.D Ib '/ 4 ATOMIC ENERGY COMMISSION l
WASHINGTON. O.C. 20545
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JUL 2 E73 R. C. DeYoung, Assistant Director for Pressurized Water Reactors, L ADDITIONAL TESTIMONY ON NORTH ANNA UNITS 3 & 4 The hearing board for North Anna 3 & 4 asked for supplemental testimony from the staff in regard to consequences of the extreme rod ejection acci-dent. B&W has traditionally included in their accident analyses an esti-mate of the ejected rod worth sufficient to cause severe pressure vessel damage.
In general, they c.alculated a TNT-c.harge weight sufficient to cause 50% ultimate strain. Then, af ter accounting for corrections due to the slower release of energy of a nuclear" excursion, they calculated an equivalent rod worth.
For the Oconee class, the rod worth was between 1.5
- 2.0%.
By contrast, the North Anna 3-4 value is only 0.8%.
The technique curantly used by B&W is to convert all the energy liberated by the transient, with thr. suitable corrections aforemantioned, to TNT-equivalence. We do nor believe this to be a credible sequence.
If we did, we would not recommend a potential tech-spec rod worth of 0.65% side-by-side with a 0.8% vessel failure value. Our qpinion is that a 0.8% ejected rod worth will not lead to significant expulsion of molten fuel past the cladding, and thus, there is no mechanism for a prompt energy spike to the primary cociant system.
We, in Reactor Safety, have not reviewed the vessel failur,e calculation.
If necessary, Engineering:TR could assist you.
The source reference used t
by B&W is a NOL document authorized by the staff consultant, James Proctor.
You may wish to censult with him regarding the board rcsponse.
Please notify me as soon as possible whether Core Performance Branch personnel will be needed to personally sponsor this supplemental testimony, and on what time scale.
Y A
J J
Yictor Stello, Jr., Assistant Director for Reacto! Safety Directorate of Licensing cc: S. Hanauer, DRTA J. Hendrie, L:TR.
F. Schroeder, L:TR D. Kartalia, OGC R. Maccary, L D. Ross, L:CPB A. Schwencer, L:PWR-4 S. Pawlicki..L H. Richings, L:CPB~
R. Ferguson, L:PWR-4
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