ML20081F702

Informs That Automatic Overfill Protection for Steam Generators Not Necessary at Unit 2 & 3,per GL 89-19

ML20081F702
Person / Time
Site:	San Onofre
Issue date:	03/20/1995
From:	Marsh W SOUTHERN CALIFORNIA EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-89-19, TAC-M74994, TAC-M74995, NUDOCS 9503220231
Download: ML20081F702 (2)

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.' Southem Califomia Edison Compsny 23 PARKER STREET tRVINE, CALIFORNIA 92M8 l

wAtren cmAnsa March 20, 1995 m-=

U. S. Nuclear Regulatory Commission l Attention: Document Control Desk  ;

Washington, D.C. 20555 Gentlemen:.

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Subject:

Docket Nos. 50-361 and 50-362 I Steam Generator Overfill Protection (TAC Nos. 74994/5)

San Onofre Nuclear Generating Station Units 2 and 3

References:

1. Septembar 13, 1994 letter from Cecil 0. Thomas, Jr. (NRC) to John J. Hutchinson (CE0G),

Subject:

NRC Generic Letter 89-19, CE0G Concerns Regarding Steam Generator Overfill Protection (SG0P)  :

2. October 31, 1990 letter (CE0G-90--736) from John J.

Hutchinson (CE0G) to Scott Newberry (NRC),

Subject:

NRC ]

Generic Letter 89-19, CE0G Concerns Regarding Steam i Generator Overfill Protection (SG0P)

, 3. March 30, 1993 letter from R. M. Rosenblum (Edison) to Document Control Desk (NRC),

Subject:

Steam Generator  :

Overfill Protection' System (TAC Nos. 74994/5), San Onofre Nuclear Generating Station, Units 2 anr' 3  :

Reference 1 provided the NRC Safety Evaluation Report of the Combustion i Engineering Owners' Group (CEOG) October 31, 1990 response (reference 2) to- I Generic Letter 89-19, " Safety Implication of Control Systems in LWR Nuclear Power Plants." The NRC staff found that automatic overfill protection for the steam generators in Combustion Engineering plants is not necessary if two conditions are met. These two conditions are that plant licensees

1) implement appropriate operator training and procedures to address steam generator overfill events and the small-break Loss of Coolant Accident (LOCA) scenarios and 2) perform an evaluation to confirm the applicability to their plants of the CE0G analyses of the assumptions and information used in the cost / benefit analysis for proposed automatic steam generator overfill protection.

As documented in reference 3, Southern California Edison (Edison) implemented appropriate operator training and procedures and performed an evaluation which .)

confirmed the applicability of the CE0G analyses to San Onofre Units 2 and 3  !

to address steam generator overfill events. In addition, appropriate operator training and procedures have been implemented consistent with the CE0G  ;

information submitted to the NRC by reference 2 for the small-break LOCA  !

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scenarios. Specifically, procedures include depressurization of the Reactor Coolant System (RCS) to reduce primary to secondary leakage and a guideline addresses replenishing the Refueling Water Storage Tanks (RWSTs).

The LOCA, Steam Generator Tube Rupture, and functional Recovery emergency operating instructions (E01s) instruct the operator to frequently monitor RWST level. If RWST level falls and sump level does not concurrently rise, the instructions state " REQUEST Shift Superintendent or Operations Leader to evaluate method to maintain RWST level - greater than 19%." The Technical Leader in the Technical Support Center (TSC), in coordination with the Operations Leader, has a set of guidelines available which aid the TSC personnel in providing timely and appropriate recommendations to the operating crew during an operating event. One of these guidelines provides I considerations and recommendations to replenish the RWST. Potential water replacement sources listed in the guideline include the concentrated boric acid storage tank via the boric acid makeup tanks, spent fuel pool, and primary radwaste tanks. To select the refill method and replacement source, the guideline provides the Technical Leader with several considerations: the available versus required shutdown margin, fill rate, inventory, and alignment  !

time. The guideline was developed because the listed variables to consider l would be so numerous that they preclude use of prescriptive step-by-step instructions. 1 Operator training on the LOCA, Steam Generator Tube Rupture, and Functional Recovery E0!s addresses the frequent monitoring of RWST level and obtaining  !

guidance from the TSC as discussed above.

I Because Edison has confirmed the applicabil'ty of the CE0G analyses and has  !

implemented appropriate operator training aid procedures to address steam generator overfill and small-break LOCA scenarios, automatic overfill protection for the steam generators is not necessary at San Onofre Units 2 and 3.

If you have any questions on this subject, please contact me.

Sincerely, dl 0 cc: L. J. Callan, Regional Administrator, NRC Region IV A. B. Beach, Director, Division of Reactor Projects, Region IV K. E. Perkins, Jr., Director, Walnut Creek Field Office, NRC Region IV J. A. Sloan, NRC Senior Resident Inspector, San Onofre Units 2 & 3 H. D. Fields, NRC Project Manager, San Onofre Units 2 and 3 e