ML13312A684
| ML13312A684 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 04/16/1993 |
| From: | Marsh W SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-92-08, GL-92-8, IEB-92-001, IEB-92-1, NUDOCS 9304190290 | |
| Download: ML13312A684 (8) | |
Text
Southern California Edison Company 23 PARKER STREET IRVINE, CALIFORNIA 92718 WALTER C. MARSH TELEPHONE ASSISTANT MANAGER, (714) 454-4403 NUCLEAR REGULATORY AFFAIRS April 16, 1993 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555 Gentlemen:
Subject:
Docket Nos. 50-206, 50-361, and 50-362 San Onofre Nuclear Generating Station Units 1, 2 and 3
References:
A.R. M. Rosenblum (SCE) to Document Control Desk (NRC) letter dated July 30, 1992, Response to NRC Bulletin 92-01, "Failure of Thermo-Lag 330 Fire Barrier System."
B.W. C. Marsh (SCE) to Document Control Desk (NRC) letter dated September 30, 1992, Response to NRC Bulletin 92-01, Supplement 1, "Failure of Thermo-Lag 330 Fire Barrier System to Perform Its Specified Fire Endurance Function."
This letter provides Southern California Edison's (SCE's) response to NRC Generic Letter 92-08, "Thermo-Lag 330-1 Fire Barriers."
The details of our response to this Generic Letter are documented in the enclosure to this letter and are summarized below.
As previously stated in SCE's responses to NRC Bulletin 92-01 and its Supplement (References A and B), SCE installed Thermo-Lag 330-1 as a Fire Barrier Material in three separate applications at Unit 1 to satisfy the requirements of 10 CFR 50.48. Because San Onofre Unit 1 is now permanently shut down, applications #1 and #3 (each application is described in the enclosure to this letter) are no longer required by the Technical Specifications to be operable. Consequently, compensatory measures for application #1 and #3 fire barriers are no longer required and have been terminated. Compensatory measures for application #2 will continue until it is no longer required by the Technical Specifications to be operable.
9304190290 930416 PDR ADOCK 05000206
- I P
Document Control Desk
- 2 As also stated in SCE's responses to NRC Bulletin 92-01 and its supplement (References A and B), SCE installed Thermo-Lag 330-1 in a fourth application at San Onofre Units 2 and 3 to satisfy the train separation requirement of 10 CFR 50, Appendix R. To respond to the NRC's concerns related to Thermo-Lag 330-1, SCE will replace the existing Thermo-Lag 330-1 at Units 2 and 3 with a material that satisfies SCE's previous licensing commitments. SCE currently plans to complete this replacement by December 30, 1993. As required by the Technical Specifications, compensatory measures are currently in-place and they will remain in-place until these fire barriers have been replaced.
If you have any questions, please contact me.
Very truly yours, Enclosure cc:
J. B. Martin, Regional Administrator, NRC Region V S. W. Brown, NRC Project Manager, San Onofre Unit 1 M. B. Fields, NRC Project Manager, San Onofre Units 2 and 3 C. W. Caldwell, NRC Senior Resident Inspector, San Onofre Units 1, 2 and 3 R. F. Dudley, Section Chief, Non-Power, Decommissioning, and Environmental Project, Directorate of Reactor Projects-3,4 and 5
Enclosure
Response to NRC Generic Letter 92-08 San Onofre Units 1, 2, and 3
Background
Thermo-Lag 330-1 is installed in the following four applications at San Onofre Units 1, 2, and 3:
Application #1 consists of 1 and 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> pre-formed panels used in Unit 1 to provide fire rated protection of cable trays, conduits, electrical equipment, and junction boxes.
The plant areas which credit Thermo-Lag 330-1 are fire areas 1-YD-20-4B (west penetration area), 1-PB-14-8 (4 kv room),
and 1-YD-14-4D (northwest yard area).
Application #2 consists of Thermo-Lag material located in portions of the Unit 1 north turbine wall which separates fire zones 1-YD-20-4A and 1-YD-20-4B from fire area 1-TB-9-9A. This material is applied (sprayed-on) directly to unistrut which supports components of the wall.
Application #3 consists of Thermo-Lag material in Unit 1 to provide (1) non-fire rated fire stops on horizontal trays and (2) non-fire rated radiant energy shields inside containment. The fire stops were installed in cable trays to prevent fire propagation from one fire zone (1-YD-20-4B) to another (1-YD-14-4D).
Additionally, the non-rated Thermo-Lag radiant energy shields were used to protect physical barriers between redundant components inside containment (1-CO-(-10)-1).
Application #4 consists of Thermo-Lag material in Units 2 and 3 tendon access hatches which separate fire zones 2/3-PE-45-3A and 2/3-PE-63-3B.
NRC Reporting Requirement 1:
State whether Thermo-Lag 330-1 barriers are relied upon (a) to meet 10 CFR 50.48, to achieve physical independence of electrical systems, (b) to meet a condition of the plant's operating license, or (c) to satisfy a licensing commitment. If applicable, state that Thermo-Lag 330-1 is not used at the facility. This generic letter applies to all 1-hour and all 3-hour Thermo-Lag 330-1 materials and barrier systems assembled by any assembly method such as by assembling preformed panels and conduit shapes, as well as spray, trowel and brush-on applications.
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SCE Response:
Unit 1:
Thermo-Lag barriers were used in the following fire areas/zone at Unit 1 to satisfy the requirements of 10 CFR 50.48:
1-YD-20-4B West Penetration Area 1-YD-20-4A East Penetration Area 1-TB-9-9A North Turbine Area 1-PB-14-8 4 kv Room 1-YD-14-4D Northwest Yard 1-CO-(-10)-1 Containment The Thermo-Lag barriers in the areas above were provided to ensure that redundant electrical components would remain free of fire damage in accordance with 10 CFR 50, Appendix R, Section III.G.
(Applications #1, #2, and #3 described above).
Additionally, application #2 was installed to comply with the requirements of Amendment 44 to the Unit 1 Provisional Operating License. This amendment required the north wall of the Unit 1 turbine building to be upgraded to provide a 1-hour fire rating.
Units 2 and 3 Thermo-Lag 330-1 is used at Units 2 and 3 to satisfy the train separation requirement of 10 CFR 50, Appendix R for redundant safety-related trains. Four individual Thermo-Lag 330-1 barriers are used to separate the fire areas described below:
Unit 2 - Barriers between 2-PE-63-3B and 2-PE-45-3A (Tendon Access Hatches)
Unit 3 - Barriers between 3-PE-63-3B and 3-PE-45-3A (Tendon Access Hatches)
(Application #4 described above).
This application was also discussed in Appendix R deviation requests submitted to the NRC by letter dated May 31, 1987 and revised by letter dated November 20, 1987 (Deviation Request Nos. 1 and 2 for Units 2 and 3, respectively).
These deviations were requested because the floors between fire areas 2/3-PE-63-3B and 2/3-PE-45-3A are 2-hour rated while Section III.G.2 of Appendix R of 10 CFR 50 requires a 3-hour barrier. In this deviation request, SCE committed to construct barriers (the hatch covers) of fire retardant material that would provide protection equivalent to a 2-hour rated barrier.
The NRC approved this deviation request by SER dated June 29, 1988 (pages 20 & 21).
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NRC Reporting Requirement 2:
If Thermo-Lag 330-1 barriers are used at the facility, (a) State whether or not the licensee has qualified the Thermo-Lag 330-1 fire barriers by conducting fire endurance tests in accordance with the NRC's requirements and guidance or licensing commitments.
(b) State (1) whether or not the fire barrier configurations installed in the plant represent the materials, workmanship, methods of assembly, dimensions, and configurations of the qualification test assembly configurations; and (2) whether or not the licensee has evaluated any deviations from tested configurations.
(c) State (1) whether or not the as-built Thermo-Lag 330-1 barrier configurations are consistent with the barrier configurations used during the ampacity derating tests relied upon by the licensee for the ampacity derating factors used for all raceways protected by Thermo-Lag 330-1 (for fire protection of safe shutdown capability or to achieve physical independence of electrical systems) and (2) whether or not the ampacity derating test results relied upon by the licensee are correct and applicable to plant design.
SCE Response:
Unit 1:
2a.
SCE did not perform any specific fire testing to qualify Thermo-Lag 330-1 fire barriers installed at Unit 1.
2b.
SCE has not performed a complete verification of the installed Thermo-Lag 330-1 fire barriers to determine operability or deviations from tested configurations.
Therefore, a detailed analysis to determine whether or not the fire barrier configurations installed in the plant represent the materials, workmanship, methods of assembly, dimensions, and configurations of the qualification test assembly configurations has not been performed. However, some installation deficiencies have been noted and documented in non-conformance reports. Because Unit 1 is now permanently shut down, SCE will not perform operability/reportability evaluations on any Thermo-Lag 330 barriers. SCE believes this correspondence adequately addresses any reporting requirements.
(Compensatory measures for barriers that are still required to be operable are discussed in our response to Question 3).
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2c.
SCE has not performed a complete verification of the installed Thermo-Lag 330-1 fire barriers. Therefore, a detailed analysis of whether or not the as-built Thermo-Lag 330-1 barrier configurations are consistent with the barrier configurations used during the ampacity derating tests has not been performed. Because San Onofre Unit 1 is now permanently shut down, Appendix R systems are no longer required to be operable. Potentially improperly derated cables required to support Appendix R requirements are not a concern and will not be evaluated.
Thermo-Lag 330-1 is also installed as fire stops in some non-Appendix R cable trays/raceways and in the north turbine wall.
Ampacity derating evaluations do not currently exist for these applications. Cables are typically oversized by a 25% factor, therefore, considerable margin exists to minimize or preclude any ampacity derating effects. Furthermore, most cables passing through these fire stops have already been deenergized as part of the plant decommissioning process.
None of the cables passing through these fire stops will be required by the Unit's permanently defueled Technical Specifications (which will take effect in August, 1993) to be operable. Therefore, such evaluations are not warranted.
Units 2 and 3:
2a.
SCE did not qualify Thermo-Lag 330-1 barriers installed at Units 2 and 3 by specific fire testing of the installed configurations. As part of our Deviation Requests, SCE committed to construct hatch covers of fire retardant material that would provide protection equivalent to a 2-hour rated barrier. The NRC approved this deviation request by SER dated June 29, 1988 (pages 20 & 21).
2b.
SCE has not performed a complete verification of the installed Thermo-Lag 330-1 fire barriers to determine operability or deviations from tested configurations. SCE will replace the existing Thermo-Lag 330-1 at Units 2 and 3 with a material that satisfies SCE's previous licensing commitments.
Therefore, additional evaluations of the Thermo-Lag 330-1 fire barriers installed at Units 2 and 3 is not required (Also, see response 2a).
2c.
The Thermo-Lag 330-1 fire barriers are used at Units 2 and 3 in the floors between fire areas 2/3-PE-63-3B and 2/3-PE-45-3A.
The barriers do not provide protection for cable trays or conduits and, therefore, ampacity derating due to Thermo-Lag 330-1 does not apply to these fire barriers.
Additionally, SCE will replace the existing Thermo-Lag 330-1 at Units 2 and 3 with a material that satisfies SCE's previous licensing commitments.
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NRC Reporting Requirement 3:
With respect to any answer to items 2(a), 2(b), or 2(c), above in the negative, (a) describe all corrective actions needed and include a schedule by which such actions shall be completed and (b) describe all compensatory measures taken in accordance with the Technical Specification or administrative controls. When corrective actions have been completed, confirm in writing their completion.
SCE Response:
Unit 1:
Because San Onofre Unit 1 is now permanently shut down, applications
- 1 and #3 are no longer required by the Technical Specifications to be operable. Consequently, compensatory measures for application #1 and #3 fire barriers are no longer required and have been terminated. Compensatory measures for application #2 will continue until it is no longer required by the Technical Specifications to be operable.
Units 2 and 3:
To respond to the NRC's concerns related to Thermo-Lag 330-1, SCE will replace the existing Thermo-Lag 330-1 at Units 2 and 3 with a material that satisfies SCE's previous licensing commitments. SCE currently plans to complete this replacement by December 30, 1993.
As required by the Technical Specifications, compensatory measures are currently in-place and they will remain in-place until these fire barriers have been replaced. SCE will provide a confirmatory letter after these barriers have been replaced.
NRC Reporting Requirement 4:
List all Thermo-Lag 330-1 barriers for which answers to item 2 can not be provided in the response due within 120 days from the date of this letter, and include a schedule by which such answers shall be provided.
SCE Response, Units 1. 2, and 3:
None.
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