ML17194B283
| ML17194B283 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 09/02/1982 |
| From: | Oconnor P Office of Nuclear Reactor Regulation |
| To: | Delgeorge L COMMONWEALTH EDISON CO. |
| References | |
| TASK-15-18, TASK-RR LSO5-82-09-016, LSO5-82-9-16, NUDOCS 8209080399 | |
| Download: ML17194B283 (3) | |
Text
Docket No~ 50-237 LSOS09-016 Mr. L. De 1 George A'...
Director of Nuclear Licensing Commonwealth Edison Company.
Post. Office Box 767 Chicago, Illinois 60690
Dear M~. DelGeorge:
_ September 2, 1982
SUBJECT:
SEP TOPIC XV-18, RADIOLOGICAL CONSEQUENCES OF A MAIN STEAM LINE FAILURE OUTSIDE CONTAINMENT DRESDEN NUCLEAR POWER STATION, UNIT 2 By letter dated May 21, 1982, you provided comments on the staff safety evaluation report ("SER) dated February 5, 1982 for SEP Topic XV-18.
Your contention was that the staff's SER was done using very conservative assumptions and that a more detailed analysis should be performed in
.order to justify the staff's conclusion regarding adoption of Standard
- Technical Specifications.
The staff agrees that it used conservative assumptions, but does not agree with your conclusion.
Each of the staff assumptions highlighted is discussed below.
Your letter stated that the ground level release atmospheric dispersion factors used by the staff are too conservative and that use of an eleva-ted release value would have produced values less than those calculated by *the staff.
The ground level re.lease value used by the staff for the exclusion area boundary-was obtained from the results of the staff review of the SEP Topic Il-2.C and did not account for fumigation conditions*
during the accident.
The staff agrees that the doses following a steam line break for a boiling w~ter reactor should assume that the release oc-curs at a height of 30 meters.
However, Regulatory Guide 1.5 also states that fumigation conditions should be assumed present during the post'ul ated rele~ses *.
Using the methodology outlined in Regulatory Guide 1.5 and the appropriate exclusion area boundary distance, the elevated release value would actually result in an 1ncr~ase in the calculated radiological
.consequences.
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't.PMr. You also stated that the staff based their evaluation on primary coolant mass releases assuming a main steam isolation valve (MSIV) closure ti~e of 10.5 seconds when the current Technical Specifications require closure time of 5 seconds or 1 ess.
The staff agrees with this comment; however, the staff evaluation is based upon the information provided to us in your
. submittal dated October 15, 1981 *. In that submittal you assumed a mass rel~ase based upon a MSIV closure time of 10.5 seconds, even thoug~ the Technical Speci f.ication *was _lower.
You al so referenced the analysis of a main steam line break outside containment in Chapter 14 of your FSAR as being appropriate for Dresden 2.
The staff values used in its evaluation are simply the values referenced by you as being acceptable values.
Lastly, you stated that the staff a$sumed the primary cqolant concentration to be 20 µci/ml iodine-131 instead of the specification value of 20 µci/ml
- gros~ iodine.
The difficulty with the current specification is that is does not identify a maximum d_fstribution of iodine isotopes in the coolant.
Without this limitation, the iodine isotopic concentrations could vary dramatically.
We recognize the conservatism in the staff calculation.
However, because of the uncertainty of the isotopic distribution, the staff chose a worst case* value to assure that the postulated off site consequences are conservative. Other problems associated with.the present iodine speci-fication have been previously discussed in our February 5, 1982 SER..
Since you have not provi.ded any information regarding coolant iodine con-centrations, we conclude that our conservative assumption of 20 uci/ml iodine-131 is still appropriate.
Therefore, WE;! conclude that the staff SER provided in our February 5, 1982 letter is appropria~e for Dresden 2 and ts considered fi~al. The need for implementation of Standard Techniq1l Specif1c~tions wil 1 be evaluated during the Integrated Asses5ment for your facility.
cc:
See next page Sincerely, Original signe*d by:
Paul H. O'Connor, Project Manager Operating Reactors Branch No~ 5 Division of Ljcensing OFFICE. *~*
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NRC FORM 318 (10-80) NRCM 0240 OFFICIAL RECORD COPY USGPO: 1981-335-960
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Mr. L. DelGeorge cc Robert G. Fitzgibbons Jr.
Isham, Lincoln & Beale Coun~elors at Law Three first National Plaza
- suite 5200 Chicago, Illinois 60602 Mr. B. B. Stephenson Plant Superintendent-Dresden Nuclear Power Station Rural Route #1 Merri,, Illinois 60450
-_The.Honorable Tom C~rcoran United States House of Represent"atives Washington, D. C.
20515
- u *. S. Nuclear Regulatory Commission R~sident Inspectors Office Dresden Station RR 11 Morris, Illinois 60450 Mary Jo Murray Assistant Attorney General Environmental Control Division -
188 W. Randolph Street Suite 2315 Chicago, Illinois 60601_
Chainnan Board of Supervisors of cGrundy County Grunay*tounty Courthouse Morris, Illinois 60450 John F. Wolf, Esquire 3409 Shepherd Street
- Chevy Chase; Maryland 20015 Dr. Linda W. Little 500 Hennitage Drive Raleigh, North Caroli11a 27612_
Judge Forrest J. Remick
-_The Carri age House - Apartment 205 2201 L Street, N. w.
Washington, D. c. 20037 Dresden 2 Docket No. 50-237 Revised 5/19/82 Illinois* Department of Nuclear Safety 1035 Outer Park Drive, 5th Floor Springfield, Illinois 62704 U. S. Environmental Protection Agency Federal Activities Branch.
Region V Office ATTN:
Regional Radiation Representative 230 South Dearborn Street Chicago, Illinois 60604 James G. Keppler~ Regional Administrator Nuclear Regulatory Commission, Region Ill 799 Roosevelt Street Glen Ellyn, Illinois 60137
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