ML19331B392
| ML19331B392 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 07/07/1980 |
| From: | Novak T Office of Nuclear Reactor Regulation |
| To: | Peoples D COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 8008120018 | |
| Download: ML19331B392 (4) | |
Text
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- j July 7, 1980 Docket Nos. 50-295 and 50-304 Mr. D. Louis Peoples Director of Nuclear Licensing Commonwealth Edison Company Post Office Box 767 Chicago, Illinois 60690
Dear Mr. Peoples:
In your letter of May 9,1980 you provided Offshore Power Systems Report No. 36A75, "An Evaluation of the Residual Risk from the Indian Point and Zion Nuclear Power Plants," dated February 1980.
Based on our review for Zion Station only, we need additional information shown in the enclosure. Thus, we request that you submit the additional information (provided to you by telecopy on June 27, 1980) shown in the enclosure no later than July 22, 1980.
Sincerely, Q%
.-n inomas M. Novak, Assistant Director for Operating Reactors Division of Licensing
Enclosure:
Request for Additional Information cc: w/ enclosure See next page so0 812 0 cit p
I
Mr. D. Louis Peoples Commonwealth Edison Company July 7,1980 cc: Robert J. Vollen, Esquire
' 5-109 North Dearborn Street Chicago, Illinois 60602 Dr. Cecil Lue-Hing Director of Research and Development Metropolitan Sanitary District of Greater Chicago 100 East Erie Street Chicago, Illinois ' 60611 Zion-Benton Public Library District 2600 Emmaus Avenue Zicn, Illincis 6C099 Mr. Phillip P. Steptce Isham, Lincoln and Beale Counselors at Law One First National ?laza 42nd Floor Chicago, Illinois 60603 Susan N. Sekuler, Esquire Assistant Attorney General Environmental Centrol Division 188 West Randolph Street, Suite 2315 Chicago, Illinois 60601 U. S. Nuclear Regulatory Ccamissien Resident Inspectors Office Post Office Box 288 Deerfield, Illinois 60015
EVALUATION OF RESIDUAL RISK - ZION REQUEST FOR INFORMATION This request was generated as a result of our continuing review of "An Evalua-tion of the Residual Risk From the Indian Point and Zion ;;uclear Power Plants,"
Offshcre Power Systems, Report No. 36A75, February 1980.
1.
Provide a compilation of data and analyses in support of all plant-specific probability estimates which differ from those used in WASH-1400. This includes the availability of offsite power, diesel generator failure, and the effect of the Shift Technical Advisor.
2.
Regarding the deletion of sequence S C, provide a probabilistic estimate 2
and basis for fan cooler failure due to. blocking of the fan cooler filters by particulates in the cnntainment atmosphere when the containment sprays are inoperable. Also, provide a probability estimate and basis for failures of both the containment spray heat sink and the fan cooler heat sink.
Include common mode failures.
3.
Evaluate the capability and sufficiency of the " feed and bleed" option for primary system heat removal specifically for Zion.
Include in your evalua-tion the failure probability and basis resulting from reliance on equipment not qualified for the environments associated with this mode of plant operation.
4.
In reference to the LPRS failure ccmbinations shown on page 20, only
" 1 and 3 " is indicated as leading to both CSRS end LFRS failures.
Provide an evaluation to show whether a common mode mechanism exists to couple a
" 1 and 4 " or a " 2 and 3 " with an additional failure further down the CSRS (not shown), which would also cause failure of both the LPRS and the CSRS.
5.
Provide all minimum requirenents for successful system operation (e.'g., one out of four pumps, etc.), What is the effect of break location on the minimum requirements?
6.
Provide more explicit references (i.e., page number / figure numuer/ table number) for all referenced failure data, whether from WASH-1400 or from other sources.
7.
In certain small break accident sequences, the reactor coolant system may repressurize, especially if there is a loss of all auxiliary feedwater.
What high pressure pumps are available in this case? Are only the charging pumps and not the high head safety injection pumps available?
(SeeFSAR,
- p. 6.2-8, where it is stated that the pumps develop a raximum discharge pressure of 1500 psig at shutoff). What are the safety grade qualifications of the available pumps?
8.
There has been some concern (see proceeding of the Topical Meeting on Probabilistic Analysis of Nuclear Reactor Safety held in Newport Beach, California May 8-10, 1978, sponsored by ANS, p. XII.3-8) that the primary pump seals may be sufficiently damaged t6 produce the equivalent of a small Loss-of-Coolant Accident, given a total loss of electric supply exceeding one hour, since the primary pump seals would no longer be cooled; the fact that the pumps are tripped is not re'evant. Provide information concerning this accident sequence.
General Comments The following comments are provided for your information:
1.
The calculation of P 9 on page 23 does not inciude any contribution from MOV failure. This comment pertains also to the calculation of P 4 on page 16.
The failure combinations presented on page 24 include some inaccuracies.
For instance, element 6 in the last combination on that page is unnecessary in view of the combination " 6 and (1 or 2)", already specified. Also, certain triple-combinations, such as "(10 or 11) and (1 or 2) and 5" and
"(3 or 4), and 6 and 9", have not been included.
3.
Probabilities P 6 and P 7 on page 16 do not compute frcm the elements quantified on the accompanying diagram.
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