ML19210A579
| ML19210A579 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 01/07/1969 |
| From: | Morris P US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Neidig R METROPOLITAN EDISON CO. |
| References | |
| NUDOCS 7910300618 | |
| Download: ML19210A579 (2) | |
Text
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w 2R; Reading nr -j Reading Docket No. 50-289 orig: p73c33 ER Reading M. M. Mann R. S. Ecyd L. Kornblith, CO (2 )
Metropolitan Edison Company F. W. Karas P.O. Box 542 bec: J. R. Euchanan, ORUL Reading, Pennsylvania 19603 Attention:
Mr. R. E. Neidig Vice President Gentlemen:
This is in reply to your letter of December 10,1%8 in which 3eu state that the control rod drives for the Three Mile Island Nuclear f.tt. tion vill be hemetically sealed, synchronous motor-driven roller-nut t nits instead of the rack-and-pinion units as previously described.
You have referenced your proposed new design to infomation contained in the Oyster Creek Unit No. 2 Application, Amendment 4 (Docket 50-320).
We have not cor-deted our review for the constmetion pemit for Oyster Creek Unit 2 and therefore have not formed a conclusion as to the adequacy of design for that application.
In reviewing the control rod drive aspects of the Three Mile Island Preliminary Safety Analysis Report, our safety evaluation of the Three Mile Island application, and the transcript of the Three Mile Island public hearing, the following points of uifference appear to exist between the two rod drive systems:
1.
The roller-nut system no longer has the capability to drive in a " stuck rM" equivalent to a 400-lb vei ht.
6 2.
The roller-nut system has a run speed of 30 inches / minute, compared to 25 inches / minute for the rack-and-pinion system.
3 The roller-nut system has no seal vater injection.
4.
The rod drive positica indication system has been changed to a more indirect means of inferring rod position.
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Form AEC.318 (Rev,9-53) u 5 GovtawtNTPamtmG crTKt.Ine-o-2ws 9 7910800 6//f g
Metropolitan Edison Company January 7, 1969 5
As stated in our safety evaluation, upward motion without a rod withdrawal signal is denied by a unidirectional clutch in the rack-and-pinion system. It is not clear whether this feature has been retained in the roller-nut system.
In consideration of these points we plan to reevaluate the adequacy of the design of the control rod drives. Our concerns vill include:
reanalysis of the startup accident, (as a result of a faster nominal drive speed); reevaluation of rod ejection accident, (as a result of
' the change in housing design); examination of quality assurance programs associated with the procurement and fabrication of the rod drives; examination of the revised relationship of the control rod drive power system and position indicaticn systems as related to the control and protection system; and a co=prehensive review of any additional criteria expressed in the reconi on Three Mile Island Station.
In our opinion, evaluation of the change in control rod drive can
'operly be deferred until your application for a provisional operating license is filed. We believe, however, that potential delays in the operating review might be avoided by an early response to the concerns expressed in this letter.
Sincerely yours,
/5/
Peter A. Morris, Director Division of Reactor Licensing cc:
George F. Trowbridge, Esq.
Shaw, Pitt=an, Potts, Trowbridge, Madden, & Stuart Suite 1017 Barr Building 91017th Street, NW Washington, DC 20006 1492 002
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