ML15223A831

Forwards Request for Addl Info Needed to Complete Review of Re Tornado Protected Means of Providing Steam Generator Cooling Water

ML15223A831
Person / Time
Site:	Oconee
Issue date:	10/18/1982
From:	Stolz J Office of Nuclear Reactor Regulation
To:	Tucker H DUKE POWER CO.
References
NUDOCS 8211060675
Download: ML15223A831 (4)

Text

OCTOBERI 9 DISTRIBUTION:

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PWagner AEOD NRC RIngram JSTaylor, IE L PDR Gray File EJordan, IE ORB#4 Rdg OParr ACRS-10 TChan HOrnstein pockets Nos. 50-269, 270 EBlackwood and 287 Mr. Hal B. Tucker Vice President, Nuclear Production Duke Power Company P. 0. Box 33189 422 South Church Street Charlotte, North Carolina 28242

Dear Mr. Tucker:

We have reviewed the information provided in your August 6, 1982 letter concerning a tornado protected means of providing steam generator cooling water and find that we require additional infor mation in order to complete our review. We, therefore request that you respond to the enclosed questions within 30 days of their receipt.

After review of the enclosed question, if you so desire, we would be available for a telephone conference or a meeting to exchange addi tional information. Please contact your Projett Manager to make any arrangements.

Since this request relates solely to the Oconee Nuclear Station, fewer than ten respondents are affected; therefore, OMB clearance is not required under P. L.96-511.

Sincerely, John F.-gtM.K S

d e f Operating Reactors Branch #4 Division of Licensing cc:

See next page 8211060675 821018 PDR ADOCK 05000269 P

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8 NRCOFORM 318 (10-80) NRCMO0240 OFFICIAL RECORD COPY usGPo:1I981-35-960

Duke Power Company cc w/enclosure(s):

Mr. William L. Porter Duke Power Company P. 0. Box 33189 422 South Church Street Office of Intergovernmental Relations Charlotte, North Carolina 28242 116 West Jones Street Raleigh, North Carolina 27603 Honorable James M. Phinney County Supervisor of Oconee County Walhalla, South Carolina 29621 Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission, Region II 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303 Regional Radiation Representative EPA Region IV 345 Courtland Street, N.E.

Atlanta, Georgia 30308 William T. Orders Senior Resident Inspector U.S. Nuclear Regulatory Commission Route 2, Box 610 Seneca, South Carolina 29678 Mr. Robert B. Borsum Babcock & Wilcox Nuclear Power Generation Division Suite 220, 7910 Woodmont Avenue Bethesda, Maryland 20814 Manager, LIS NUS Corporation 2536 Countryside Boulevard Clearwater, Florida 33515 J. Michael McGarry, III, Esq.

DeBevoise & Liberman 1200 17th Street, N.W.

Washington, D. C. 20036

REQUEST FOR ADDITIONAL INFORMATION OCONEE NUCLEAR STATION

Reference:

DRP letter to NRC - August 6, 1982 Regarding the ability to provide steam generator cooling water following a tornado strike, provide the following information:

1. You state that the bounding evaluation of the-frequency at which a tornado might be expected to damage the EFWS and the SSF ASWS piping and controls, where they enter the reactor building through the west penetration room, showed thgt the frequency of occurrence is no higher than approximately 7.5 x 10~ /yr. for any particular Oconee unit.

Provide a description of the methodology, assumptions, modeling and error bounds of your analysis.

2.

You state that in the event of a tornado induced loss of both the main and emergency feedwater system, the steam generator inventory would be expected to be boiled off within a few minutes.

Ample time would be available for opening the manual dump valves on at least one steam generator to maintain a low back pressure for the auxiliary service water pump. Blowdown of the steam generators would not be necessary.

Provide the results of an analysis which demonstrates that-adequate decay heat removal can be continuously maintained through the use of the existing auxiliary service water system, and that such a cooldown method will not result in an accidental overpressurization of the auxiliary service water system or the excessive loss of reactor coolant. As a minimum, the following points should be addressed.

a. Since the effectiveness of water injection into the steam generator (SG) is of some concern because of the low head capacity of the ASWS, discuss the SG pressure that must be attained in order to provide sufficient ASWS flow into the SG to ensure adequate decay heat removal. Further, provide the dump valve capacity at rate ASWS pressure, and the time period assumed for operator action of the manual dump valves.

b.

Provide a discussion and analytical results (plots.if appropriate) of the transient following a reactor trip utilizing the ASWS to remove decay heat. The discussion should include reactor coolant system pressure and temperature, SG pressure, SG water level/flow rate, and decay heat removal versus time. Provide the time at which the secondary steam dump capacity will match decay heat load following a reactor trip provided that the steam generators are at the ASWS operating pressure. Following the reactor trip during the time for which decay heat is greater than the removal capability of the steam dumps at ASWS pressure, provide the mass loss through the reactor system safety valves.

Justify that core uncovery will be prevented.

-2

c.

Discuss the effects of cold shocking the steam generator as a result of injecting cold water into a relatively dry steam generator.