ML19263E735
| ML19263E735 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 05/09/1979 |
| From: | Ziemann D Office of Nuclear Reactor Regulation |
| To: | Reed C COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 7906250108 | |
| Download: ML19263E735 (3) | |
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May 9,1979 Docket No. 50-10 Mr. Cordell Reed Assistant Vice President Commonwealth Edison Company Post Office Box 767 Chicago, Illinois 60690
Dear Mr. Reed:
RE:
SEP TOPIC XV-17 Radiological Consequences of a Steam Generator Tube Failure Enclosed is a copy of our draft evaluation of Systematic Evaluation Program Topic XV-17.
You are requested to examine the facts upon which the staff has based its evaluation and respond either by confirming that the facts are correct, or by identifying any errors. If in error, please supply corrected information for the docket. We encourage you to supply for the docket any other material related to this topic that might affect the staff's evaluation.
Your response within 30 days of the date you receive this letter is requested.
If no response is received within that time, we will assume that you have no comments or corrections.
Sincerely, OI)&& >n 3lM" DennisL.Ziemann,[Ahief Operating Reactors Branch !2 Division of Operating Reactors
Enclosure:
Topic XV-17 cc w/ enclosure:
2218 284 See next page 7906250109
Mr. Cordell Reed May 9, 1979 cc w/ enclosure:
Isham, Lincoln & Beale Counselors at Law One First National Plaza. 42nd Floor Chicago, Illinois 60603 Mr. B. B. Stephenson Plant Superintendent Dresden Nuclear Power Station Rural Route =1 Morris. Illinois 60450 U. S. Nuclear Regulatory Commission ATTN-Jimmy L. Barker P. O. Box 706 Morris, Illinois 60450 Susan N. Sekuler Assistant Attorney General Environmental Control Division 188 W. Randolph Street Suite 2315 Chicago, Illinois 60601 Morris Public Library 604 Liberty Street Morris. Illinois 60451 K M C, Inc.
ATTN: Jack McEwen 1747 Pennsylvania Avenue, N. W.
Suite 1050 2218 285 Washington, D. C.
20006
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DRESDEN 1 Topic XV-17 Radiological Consequences of a Steam Generator Tube Failure The review of this topic was intended primarily for pressurized water reactor systems where the steam generator tubes act as a barrier between the primary and secondary systems. A failure of the tubes in PWRs would result in the transport of radioactivity from the primary 4
to the secondary system and therefrom to the environment.
The safety objective of this topic is to assure that the releases from this a
postulated event will not result in exposures in excess of the estab-lished guidelines.
The Dresden Unit No. 1 plant is a dual cycle boiling water reactor with the unique feature of four recirculating loops with a steam cenerator per loop.
However, there is no secondary coolant per se.
The primary a
f, fluid in the steam generators is made up of return flow from the steam drum which is thus further cooled before returning to the reactor, and e
- l the secondary fluid is the turbine condensate. Therefore, the steam generator tubes act not as a barrier, but solely as a heat transfer s
device.
The existence of a leak across the steam generator tubes is detected when the water level cannot be automatically maintained in the secondary side. A high water level signal is indicated by a light in the control room and is followed by automatic isolation of the primary and secondary sides of the faulty steam generator. However, as iri icated above, such a leak would not result in an increase of radioactivity in the turbine, since it is already being supplied with primary steam. The EWR system e
is designed to operate with radioactive steam and, therefore, no additional hazard is created by steam generator leaks.
Based on this analysis, we conclude that a postulated steam generator tube failure at the Dresden Unit No. I plant does not redJlt in worse conditions thar analyzed in other accident scenarios. This completes the evaluation of this topic with no additional SEP review required.
2218 286 5
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