ML13330B524
| ML13330B524 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 06/25/1991 |
| From: | Nandy F SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TASK-3.D.3.4, TASK-TM NUDOCS 9106260396 | |
| Download: ML13330B524 (4) | |
Text
Southern California Edison Company 23 PARKER STREET IRVINE, CALIFORNIA 92718 F. R. NANDY TELEPHONE MANAGER, NUCLEAR LICENSING June 25, 1991 (714) 454-4504 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555 Gentlemen:
Subject:
Docket No. 50-206 TMI Item III.D.3.4 Control Room Habitability San Onofre Nuclear Generating Station, Unit 1 This letter responds to the NRC Senior Project Managers' request that we document the Control Room Habitability open items resulting from our April 11, 1991 meeting with the NRC staff. We requested the meeting with the NRC to obtain feedback regarding our April 10, 1991 submittal.
Items discussed during this meeting included our proposed upgrades to the existing control room emergency HVAC system, and our revised control room operator dose calculations. During an April 19, 1991 followup telephone discussion, Mr.
Kalman requested that we. document the outstanding commitments. The enclosure to this letter lists the remaining NRC open items and provides our schedule for responding to each item.
If you have any questions regarding this information, please let me know.
Very truly yours, Enclosure cc:
George Kalman, NRC Senior Project Manager, San Onofre Unit 1 J. 0. Bradfute, NRC Project Manager, San Onofre Unit 1 J. B. Martin, Regional Administrator, NRC Region V C. W. Caldwell, NRC Senior Resident Inspector, San Onofre Units 1, 2&3 9106260396 9102#
PDIR ADOCK 05000206 P
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ENCLOSURE This document lists the remaining NRC open items for TMI Item III.D.3.4, "Control Room Habitability." Also provided is our schedule for responding to these items and a brief status of each item.
A.
As a result of our April 10, 1991 submittal, the following items require additional information:
A.1 In our submittal we indicated that the method for updating the Unit 1 offsite toxic gas hazard analysis would be similar to the procedure used for the Units 2 and 3 analysis. Every three years a survey is conducted of the I-5 highway truck traffic passing the plant.
With the results of this survey the hazard frequencies due to each chemical is determined. We committed to update the existing Unit 1 offsite toxic gas hazards analysis on a triennial basis in conjunction with the highway survey and submit the results to the NRC. We are currently evaluating the results from the recent toxic gas highway survey. This effort will be completed and an evaluation summary submitted to you by September 27, 1991.
A.2 In our submittal we committed to revise the SONGS 1 Control Room HVAC technical specifications (TS) to reflect the upgraded Control Room Emergency HVAC. The revised specifications will also require that we review and update the toxic gas hazards analysis on a triennial basis using the results from the updated traffic survey.
We will submit the revised technical specifications to you within six (6) months prior to the scheduled Cycle 12 refueling outage.
B.
As a result of our April 11, 1991 meeting with the NRC staff, the following items were identified as needing additional information:
B.1 During the meeting, the NRC asked if our proposed Control Room Emergency HVAC intake filtration unit would be using the 0.25 second residence time for each 2 inch charcoal adsorber in accordance with Regulatory Guide 1.52. In response to this question, we verified that the proposed Control Room Emergency HVAC intake unit will comply with the 0.25 second residence time per 2 inches of charcoal adsorber in accordance with Regulatory Guide 1.52, Revision 2. The proposed filter unit will consist of two banks of 2 inch charcoal adsorbers in series, each having a residence time of 0.25 seconds. This completes our response for this item.
B.2 During the meeting, the NRC pointed out that ASME AG-1 codified the requirements of ANSI 509 for HVAC systems. Since our submittal proposed to upgrade the HVAC system to meet ANSI 509-1989, the NRC requested that we ensure that the proposed upgrades meet ASME AG-1 requirements. We are evaluating the requirements of ASME AG-1 and comparing them with ANSI 509-1989.
Our evaluation will be completed and the results submitted to you by July 31, 1991.
B.3 During the meeting, the NRC asked how the Unit 1 control room operators would be notified to put the emergency HVAC system in operation in the event of a fuel handling accident or a waste gas system accident. We are evaluating these two radiological events as part of the proposed upgraded Control Room Emergency HVAC system. Our evaluation will determine if any operating procedures will require revision. Our evaluation will be completed and the results submitted to you by July 31, 1991.
B.4 In our submittal we committed to provide the recalculated control room operator whole body dose by November 1, 1991.
During the meeting, the NRC asked us to expedite our schedule for this item.
The NRC staff was concerned that they would not be able to resolve the radiological portion of the control room habitability issue until the whole body dose calculation was completed. In response to your request, we are expediting our efforts to evaluate the control room operator whole body dose. Since we propose to relocate the emergency HVAC equipment and intake, we are revising the atmospheric dispersion values used in our previous dose calculations. Our evaluation will be completed and the results submitted to you by August 30, 1991.
B.5 During the meeting, the NRC asked us to determine the ammonia concentration in the control room if manual isolation of the HVAC system occurs at two (2) minutes. The toxic gas analysis in our submittal does not credit the operator isolating the control room HVAC following the rupture of the 9,000 gallon ammonia tank at Units 2 and 3. At approximately 9.5 minutes into the event, the ammonia concentration in the control room would exceed the National Institute for Occupational Safety and Health (NIOSH)
Immediately Dangerous to Life and Health (IDLH) limits. Crediting operator action to isolate the control room, would reduce the ammonia concentration in the control room. We are reevaluating this event to determine the ammonia concentration in the control room when operator action to isolate the HVAC system occurs at two (2) minutes from the time ammonia is detected by the operators.
Our evaluation will be completed and the results submitted to you by July 31, 1991.
B.6 During the meeting, the NRC asked us tosprovide the thyroid dose that each control room operating shift would receive if the emergency HVAC system is not available during the design basis Loss of Coolant Accident (LOCA).
The evaluation of the thyroid dose to each control room operating shift will be performed with the calculation of the control room operator whole body dose.
These evaluations will be completed and the results submitted to you by August 30, 1991.
C.
The following open items were identified as a result of the April 19, 1991 telephone conversation with the NRC.
C.1 During the telephone conversation, the NRC requested that we supplement our submittal with a more detailed evaluation of our proposed requirements for use of SCBAs during a design basis LOCA.
We are currently reevaluating the need for supporting control room habitability through the use of SCBAs. This evaluation will be completed once the results from the operator thyroid dose calculation are available. Our evaluation will be completed and the results submitted to you by August 30, 1991.
C.2 During the telephone conversation, the NRC requested that we include a requirement in our technical specifications that would not allow both the Technical Support Center (TSC) and the control room emergency HVAC to be out of service simultaneously. The NRC wants us to credit the TSC HVAC as a temporary backup in the event the control room emergency HVAC system fails. We are evaluating the proposed upgrades to the TSC and control room emergency HVAC systems to determine the appropriate technical specification change needed to ensure that the required portions of both systems will not be out of service simultaneously. We will be submitting our proposed technical specification change to you within six (6) months prior to the scheduled Cycle 12 refueling outage.