ML20148P436

Forwards Request for Addl Info Re re-evaluation of Plants Component Cooling Water Sys in Light of Problems Experienced at Byron/Braidwood Plants

ML20148P436
Person / Time
Site:	Zion  File:ZionSolutions icon.png
Issue date:	04/05/1988
From:	Muller D Office of Nuclear Reactor Regulation
To:	Butterfield L COMMONWEALTH EDISON CO.
References
TAC-66759, TAC-66760, NUDOCS 8804110220
Download: ML20148P436 (5)

Text

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April 5,1988 Docket 'los. 50-295 and 50-304 DISTRIBUTION

( 9eetet411 e OGC-Rockville NRC & Local PDRs EJordan Mr. L. D. Butterfield, Jr. PDIII-2 Rdg. JPartlow Nuclear Licensing Manager DCrutchfield ACRS(10)

Ccanonwealth Edison Company GHolahan PDIII-2 Plant File Post Office Box 767 LLuther Chicago, Illincts 60690 JNorris

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATICN RELATED TO RE-EVALUATION OF ZION COMPONENT COOLING WATER SYSTEM IN LIGHT OF PROBLEMS EXPERIENCED AT THE BYRON /BRAIDWOOD PLANTS (SRP SECTION 9.2.2)

TAC NOS. 66759/60 The design of the Zion Units 1 and 2 Component Cooling Water (CCW) system is very similar to that of the Byroa and Braidwood stations. The recent events at Byron Unit 2 (11/20/86), Byron Unit 1 (4/8/87), and Braidwood Unit 1(1/21/87) indicated to the staff that the potential exists for a simultaneous loss of all CCW to both units if the system were in its normal cross-connected shared lineup for dual unit operation.

The staff has determined that more information is necessary in order to compare the system design with the current SRP Section 9.2.2 acceptance criteria and the acceptance criteria in use at the tirre of Zion licensing.

The reporting and/or recordkeeping requirements contained in this letter affect fewer than ten respondents; therefore, OMB clearance is not required

under P.L.96-511. l Sin

e ely, Original Signed by J. Norris for/

Daniel R. Muller, Director Projec; Directorate I!!-2 Division of Reactor Projects - III, IV, V and Special Projects

Enclosures:

As stated cc:

See next page PCII - M PDIII-2:LA II 2. D Jhor 1s: i LLuther]4 PDl'll r DMu 88 f/I/88 gg/88 G804110220 8380405 PDR ADOCK 05000295 P PDR ,

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joarog ge UNITED STATES 2 3 s ,(/(k p, NUCLEAR REGULATORY COMMISSION 5 # y WASHINGTON, D. C. 20555 gv ***/

April 5,1988 Docket Nos. 50-295 and 50-304 Mr. L. D. Butterfield, Jr.

Nuclear Licensing Manager Conrnonwealth Edison Company Pc3t Office Box 767 Chicago, Illinois 60690

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION RELATED TO RE-EVALUATION OF ZION COMPONENT COOLING WATER SYSTEM IN LIGHT OF PROBLEMS EXPERIENCED AT THE BYRON /BRAIDWOOD PLANTS (SRP SECTION 9.2.2)

TAC NOS. 66759/60 The design of the Zinn Units 1 and 2 Component Cooling Water (CCW) system is very similar to that of the Byron and Braidwood stations. The recent events at Byron Unit 2(11/20/86), Byron Unit 1 (4/8/87), and Braidwood Unit 1(1/21/87) indicated to the staff that the potential exists for a simultaneous loss of all CCW to both units if the system were in its nonnal cross-cor.nected shared ,

lineup for dual unit operation. l The staff has determined that more infonnation is necessary in order to compare the system design with the current SRP Section 9.2.2 acceptance criteria and the acceptance criteria in use at the time of Zion licensing.

The reporting and/or recordkeeping requirenants contained in this letter affect fewer than ten respondents; themre, OMB clearance is not required under P.L.96-511.

Sincerely. .

l I

an el . .uller, -Di rector roject Directorate III-2 0 vision of Reactor Projects - III, IV, V and Special Projects

Enclosures:

As stated CC:

See next page a

Mr. L. D. Butterfield, Jr.

Commonwealth Edison Company Zion Station cc:

Robert J. Vollen, Esq. Mr. Michael C. Parker, Chief 109 N. Dearborn Street Division of Engineering Chicago, Illinois 60602 Illinois Department of Nuclear Safety Dr. C?cil Lue-Hing 1035 Outer Park Drive 5th Floor Director of Research and Development Springfield Illinois 62704 Metropolitan Sanitary District of Greater Chicago "

100 East Erie Street Chicago, Illinois 60611 Phillip Steptoe, Esq.

Sidley and Austin One First National Plaza Chicago, Illinois 60603 Mayor of Zion Zion, Illinois 60099 Illinois Department of Nuclear Safety ATTN: Monager, Nuclear Facility 56fety 1035 Outer Park Drive, 5th Floor Snringfield, Illinois 62704 U.S. Nuclear Regulatory Commission Resident Inspectors Office 105 Shiloh Blvd.

3 Zion, Illinois 60099 Regional Administrator, Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137 I

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REQUEST FOR ADDITIONAL INFORMTION COMP 0NENT COOLING WATER SYSTEM ZION STATION, UNITS 1 AND 2 DOCKET NOS. 50-295/304

1. In the event of a LOCA in one unit while both units are operating, provide the following information:

a. Describe how nonessential portions of the CCW system are isolated in order to ensure the system safety function given a single active failure. It appears that only manual isolation capability is available in lieu of automatic features to ensure adequate CCW flow to essential components.

b. If manual actirn is required for isolation, provide. the basis for the time assumed for isolation in order to maintain CCW safety function,

c. What is the basis (cool down time of the non-LOCA unit) assumed, which results in four pumps required for operation for a LOCA in one unit and cooldown of the other unit as indicated in FSAR Table 9.3.2-17

d. Verify that the CCW system is designed to prcvide adequate cooling to both units in the event of a LOCA in one unit and a cooldown of the other unit given any single active failure as required by GDC 5.

e. Do post-LOCA recovery procedures call for splitting (train and/or unit separation) of the CCW system? If so, is the split necessary to ensure adequate flow considering all possible single active f ailures? Discuss the accessibility of thu valves requiring u nual action under post-LOCA conditions and ar.y limiting time frame for these actions.

2. Provide information (design bases) to support operation of the CCW system given a seismic event and a worst case concurrent single active failure.

3. If your desig? bases do not postulate a rupture (double ended break) of the nonseismic portion of the CCW system following a seismic event, provide supporting information which provides a basis for assumir.g the nonseismic piping will not rupture.

4. Given no seismic event, describe how the design of the system can with-stand a moderate energy leakage crack without disabling the system. For the nonseismic portion of the system, a single active failure should also be assumed. Your response should provide the basis for any assumed crack size and the time available for operator action to isolate the leak before the CCW system is disabled.

5. In the event that a pipe rupture disables the CCW system for both units, how long will it take to isolate the leak and make the system operable again? In responding to this, consider the following:

a) Are the pumps protected against a loss of suction? If so, describe the design in detail.

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2 b) How long can the loss of CCW be withstood before core darr. age given the possibility of a RCP seal LOCA without primary coolant makeup capability since the loss of CCW causes e loss of cooling water to the RCP seals and to the charging / safety injection pumps?

6. Discuss the control room instrumentation, controls and alarms associated with the CCW system and indicate whicn are redundant and which ara safety grade.

7. In light of the events at Byron /Braidwood, identify any plans for re-evaluating the design bases and operation of the CCW system at Zion.

If sur.h plans exist, what is the status of that re-evaluation and any planned changes to the system.

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