ML20155K490

Provides Update & Correction to Info Noted in to Support NRC Review of Suppl 1 to Amend Applications 138 & 122 for Songs,Units 2 & 3.Ltr Discussed Use of NUREG-0800 SRP Guidance Re tornado-generated Missiles

ML20155K490
Person / Time
Site:	San Onofre
Issue date:	11/10/1998
From:	Scherer A SOUTHERN CALIFORNIA EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9811130264
Download: ML20155K490 (7)

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.6*? ' 5001HIRN CAllf 0RNIA A. Edwud Scherer

1. E EDISON ML,m An (Ul50N 1.\TlRV t710N4L" Compuny November 10, 1998 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 Gentlemen:

SUBJECT:

Docket Nos. 50-361 and 50-362 Additional Information Regarding Amendment Application Nos. 138 and 122 Use of NUREG-0800 Standard Review Plan Guidance in Evaluating Tornado-Generated Missiles San Onofre Nuclear Generating Station, Units 2 & 3

References:

1) Letter dated March 13, 1998, from J. L. Rainsberry (SCE) to Document Control Desk (NRC),

Subject:

Docket Nos. 50-361 and 50-362, Additional Information Regarding Amendment Application Nos. 138 and 122, Use of NUREG-0800 Standard Review Plan Guidance in Evaluating Tornado-Generated Missiles, San Onofre .

Nuclear Generating Station, Units 2 and 3

2) Letter dated November 14, 1997, from Dwight. E..Nunn (SCE) to Document Control Desk (NRC),

Subject:

Docket Nos. 50-361 and 50-362 Supplement I to Amendment Application Nos. 138 and 122, Use of NUREG-0800 Standard Review Plan Guidance in Evaluating Tornado-Generated Missiles, San Onofre Nuclear Generating Station Units 2 and 3.

This letter provides an update and a correction to information that was submitted (Reference 1) to support an NRC review of Supplement 1 to Amendment  !

Applications 138 and 122 for the San Onofre Nuclear Generating Station, Units 2 and3(Reference 2). Supplement 1 to Amendment Applications 138 and 122 l consisted of Proposed Change Number (PCN) 433, Supplement 1. PCN 433, Supplement I requests a change in methodology for evaluating tornado missile protection. Additional information was submitted in Reference 1 concerning the time required to perform operator actions following a Severe Weather Warning.

Specifically, Reference 1 stated that actions to protect the station from the effects of a tornado could be completed within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> following a Severe Weather Warning. These actions included two specific operator actions that were credited in the calculations to support approval of Reference 2: closure of Control Room Lobby Missile Doors a)nd isolation of Condensate Transfer Piping.

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Document Control Desk ,

, As 's'tated in Reference 1, operator actions following receipt of a Severe Weather Warning were listed in San Onofre procedure S023-13-3, " Natural Disaster / Severe Weather," Attachment 4, " Severe Weather Preparations." Step 2.5, " Restore Important-to-Safety Systems to Service," required closure of the Control Room Lobby Missile Doors. Step 2.10 of Attachment 4, " Maximize Condensate

Inventory," required isolation of the Condensate Transfer Piping. Reference 1 stated that the estimated amount of time to complete all steps of Attachment 4 l of S023-13-3 was 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.  !

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On March 31, 1998, waterspouts were sighted off of the coast at San Onofre, which resulted in a Special Marine Advisory. The response to this event showed that while Steps 2.5 and 2.10 of Attachment 4 could have been performed within 4 i L

hours, completion of all the actions in Attachment 4 would have taken longer I than the estimated 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

Following the weather event on March 31, 1998, actions in response to Weather l Events have been moved to a separate procedure, S023-13-8, " Severe Weather." In '

accordance with the new procedure, tornado preparations would now be initiated earlier. Previously, preparations were initiated on notification of a Tornado

Warning; now, preparations are initiated at the lower threshold of notification of a Tornado Watch. Notification tources are also updated and expanded.

Some of the tornado preparations have been changed and their order in the procedure has been changed. However, the two specific operator actions credited in the proposed licensing basis have not been substantially changed. The enclosed Table 1 lists operator actions for Severe Weather as they were described in Attachment 4 to S023-13-3. The enclosed Table 2 provides the steps as described in the new S023-13-8, Attachment 1. A comparison of the steps from the old set of actions to the new set (Table 3) is also enclosed.

It should be noted that, due to personnel safety concerns, S023-13-8 contains a new precaution which states that tornado preparation steps will be completed "if  ;

possible before onset of the tornado." If, for example, a Tornado Watch was declared, Attachment I would be initiated. If a tornado was then sighted before l all tornado preparation steps were completed, and this tornado was likely to pose a threat to personnel safety, the remaining steps would not be performed.

This procedure change was completed on June 25, 1998. It is estimated that the two tornado preparation steps necessary to support the conclusions of Reference 2 can be completed within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> following notification of a Tornado Watch, j assuming that there are no personnel safety concerns due to an imminent tornado.

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Document Control Desk , Conc'lusi6n Reference 2 states that the overall annual probability of damage to critical equipment due to tornado missiles is less than 1 x 10" per unit. This conclusion is based in part on performance of two operator actions, closure of Control Room Lobby Missile Doors and isolation of Condensate Transfer Piping.

By performing tornado preparations in accordance with the old Attachment 4 of S023-13-3, these two steps would have been completed within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of receipt of a Tornado Warning. Therefore, the conclusions of Reference 2 were valid.

However, it is likely that more than 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> would have been required to complete all steps of Attachment 4 of S023-13-3.

I Following the procedure revision to move severe weather preparations to a separate procedure, it is now estimated that the two tornado preparation actions required to support the conclusions of Reference 2 can be completed within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of receipt of a Tornado Watch, assuming that there are no personnel safety concerns due to an imminent tornado. Again, the conclusions of Reference 2 i remain valid. i If you have any further questions on this subject, please call me.

Sincerely, Enclosure cc: E. W. Merschoff, Regional Administrator, NRC Region IV J. A. Sloan, NRC Senior Resident Inspector, San Onofre Units 2 & 3 J. W. Clifford, NRC Project Manager, San Onofre Units 2 and 3 l

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Enclosure Operator Actions Required in Preparation for l Severe Weather Events I l

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l Table 1 OPERATOR ACTIONS FOR SEVERE WEATHER S023-13-3, Attachment 4 ,

Receipt of Severe Weather Warning, Initiate S023-13-3, Attachment 4 Step 2.1 Perform plant management notifications Step'2.2 Plant shutdown determination Step 2.3 Perform potential missile inspections Step 2.4 Ensure adequate staffing Step 2.5 Restore important-to-safety systems to service Step 2.6 Isolate control room envelope Step 2.7 Verify 220 Kv electrical distribution system status Step 2.8 Verify the status of Class 1E distribution system Step 2.9 Verify the status of non-1E distribution system Step 2.10 Maximize condensate inventory Step 2.11 Sumps and liquid waste Step 2.12 Station blackout preparations Step 2.13 Final missile inspection Preparations complete (Senior Reactor Operator /0perationsSupervisorsignoffonAtt.4) r

Table 2 OPERATOR ACTIONS FOR SEVERE WEATHER S023-13-8, Attachment 1 Initiate S023-13-8, Attachment 1 Step 2.1 Severe Weather Verification Step 2.2 Required Actions Determination Step 2.3 Isolate-Control Room Envelope Step 2.4 Perform Plant Management Notifications  !

Step 2.5 Make PA Announcement Step 2.6 Perform Severe Weather Barrier Inspection Step 2.7_ Maximize Unit 2 Condensate Inventory Step 2.8 Maximize Unit 3 Condensate Inventory J

Step 2.9 Perform Potential Missile Inspections Step 2.10 RestoreImportant-to-SafetySystems/Componentsto Service Step 2.11* Evaluate Need for a Site Evacuation Step 2.12* Ensure Adequate Staffing Step 2.13* Verify 220 kV Electrical Distribution System Status Step 2.14* Verify Status of Class 1E Distribution System Step 2.15* Verify Status of Non-1E Distribution System l Step 2.16* Minimize Liquid Radwaste Step 2.17* Station Blackout Preparations Step 2.18 Post-Incident PA Announcement Step 2.19 Post-Incident Plant Management Notifications

*0nly required if tornado total wind speed is expected to exceed 157 mph.

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- Table 3 Comparison of Severe Weather Actions l

,. ,, Before and After Procedure Change S023-13-3 S023-13-3 Action 5023-13-8 Action Step No.

2.1 Perform plant management Moved to Step 2.4 notifications 2.2 Plant shutdown determination Part of Step 2.2, Required Actions Determination 2.3 Perform potential missile Moved to Step 2.9; requirement to inspections relocate parked vehicles outside the Protected Area has been deleted.

2.4 Ensure adequate staffing Moved to Step 2.12 2.5 Restore important-to-safety Moved to Step 2.10; closure of Control systems to service Room Lobby Missile Doors moved to Step 2.3, barrier inspections moved to Step 2.6 2.6 Isolate control room envelope Moved to Step 2.3 2.7 Verify 220 Kv electrical Moved to Step 2.13 distribution system status 2.8 Verify the status of Class 1E Moved to Step 2.14 distribution system 2.9 Verify the status of non-1E Moved to Step 2.15 distribution system 2.10 Maximize condensate inventory Moved to Steps 2.7 and 2.8 2.11 Sumps and liquid waste Moved to Step 2.16; requirement to lower sump levels to Low-Low has been deleted 2.12 Station blackout preparations Moved to Step 2.17 2.13 Final missile inspection Deleted n/a Added Step 2.1, Severe Weather Verification n/a Added Step 2.5, Make PA Announcement n/a Added Step 2.11, Evaluate Need for a Site Evacuation l

l n/a Added Step 2.18, Post-Incident PA l Announcement i n/a Added Step 2.19, Post-Incident Plant i Management Notifications

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