ML12104A197
| ML12104A197 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 04/12/2012 |
| From: | Office of Nuclear Reactor Regulation |
| To: | Division of Operating Reactor Licensing |
| References | |
| Download: ML12104A197 (9) | |
Text
WBN2Public Resource From: Milano, Patrick Sent: Thursday, April 12, 2012 11:30 AM To: Moulton, Charles; Frumkin, Daniel Cc: WBN2HearingFile Resource
Subject:
FW: TVA letter to NRC_04-12-2012_Fire Protection Report RAI Response Attachments: 04-12-2012_Fire Protection Report RAI Response_Final.pdf From: Boyd, Desiree L [1]
Sent: Thursday, April 12, 2012 10:31 AM To: Epperson, Dan; Poole, Justin; Raghavan, Rags; Milano, Patrick; Campbell, Stephen Cc: Arent, Gordon; Hamill, Carol L; Boyd, Desiree L
Subject:
TVA letter to NRC_04-12-2012_Fire Protection Report RAI Response Please see attached TVA letter that was sent to the NRC today.
Thank You,
~*~*~*~*~*~*~*~*~*~*~
Désireé L. Boyd WBN Unit 2 Licensing dlboyd@tva.gov 423-365-8764 1
Hearing Identifier: Watts_Bar_2_Operating_LA_Public Email Number: 679 Mail Envelope Properties (9C2386A0C0BC584684916F7A0482B6CA632D259966)
Subject:
FW: TVA letter to NRC_04-12-2012_Fire Protection Report RAI Response Sent Date: 4/12/2012 11:30:11 AM Received Date: 4/12/2012 11:30:13 AM From: Milano, Patrick Created By: Patrick.Milano@nrc.gov Recipients:
"WBN2HearingFile Resource" <WBN2HearingFile.Resource@nrc.gov>
Tracking Status: None "Moulton, Charles" <Charles.Moulton@nrc.gov>
Tracking Status: None "Frumkin, Daniel" <Daniel.Frumkin@nrc.gov>
Tracking Status: None Post Office: HQCLSTR02.nrc.gov Files Size Date & Time MESSAGE 594 4/12/2012 11:30:13 AM 04-12-2012_Fire Protection Report RAI Response_Final.pdf 146682 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:
Recipients Received:
Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381-2000 April 12, 2012 10 CFR 50.4 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Unit 2 NRC Docket No. 50-391
Subject:
WATTS BAR NUCLEAR PLANT (WBN) UNIT 2 - RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION (RAI) RELATED TO THE FIRE PROTECTION REPORT, GROUP 8 (TAC NO. ME3091)
Reference:
NRC letter to TVA dated March 23, 2012, Watts Bar Nuclear Plant, Unit 2 -
Request for Additional Information Regarding Final Safety Analysis Report Amendment Related to Section 9.5.1, Fire Protection System Group 8 (TAC No. ME3091)
The purpose of this letter is to respond to the four questions provided in the request for information in the reference above. Enclosure 1 provides these responses.
The referenced letter also acknowledged TVAs intent to submit another revision to the as-designed Fire Protection Report (FPR). However, the submittal of this revision will be delayed due to the recent discovery of an error in one of the Unit 2 strategies to address a fire in certain plant areas. The operator manual action (OMA) associated with this strategy will not work as analyzed. This fire protection strategy error affects both design calculations and the FPR. This discovery was communicated to WBNs NRC Project Manager by telecon on April 11, 2012.
TVA expects to complete the reanalysis and submit the revised FPR by April 27, 2012. That submittal will include a description of the strategy error and the resulting impact. provides the commitment list contained in this letter. If you have any questions, please contact Gordon Arent at (423) 365-2004.
U.S. Nuclear Regulatory Commission Page 3 April 12, 2012 bcc (Enclosures):
Stephen Campbell U.S. Nuclear Regulatory Commission MS 08H4A One White Flint North 11555 Rockville Pike Rockville, Maryland 20852-2738 Darrell Roberts, Acting Deputy Regional Administrator for Construction U. S. Nuclear Regulatory Commission Region II Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, Georgia 30303-1257
ENCLOSURE 1 TVA Responses on NRCs Group 8 RAI Follow-up Questions A public meeting was held on February 2, 2012, between the U.S. Nuclear Regulatory (NRC) staff and representatives from Tennessee Valley Authority (TVA) regarding the ongoing review of the Watts Bar Nuclear Plant Unit 2 Fire Protection Report (FPR). During the meeting, TVA presented sample fire protection evaluations to the NRC staff. The following questions relate to those samples.
Specifically the questions focused on TVA's proposed revision to Part VII, Section 2.9 Deviations.
Information to address the following questions is needed by the staff to complete the review. These questions were discussed with TVA via teleconference on February 27, 2012.
The new evaluations have removed discussion of plant trip initiators in the room. For each room, discuss plant trip initiators in that room. Describe the scenario that would have to occur for a fire to cause a plant trip, affect redundant trains of fire safe shutdown equipment or cables, or both.
TVA Response:
For the rooms in the FPR Section VII, Paragraph 2.9 deviation request, the following scenario (all steps) would have to occur for a fire of sufficient magnitude in one of the rooms to occur and cause a plant trip, affect redundant trains of fire safe shutdown (FSSD) equipment or cables, or both.
- a. Violation of the combustible control program that resulted in a large quantity of transient combustible material being brought into the room and left there.
- b. Violation of the Hot Work control program that resulted in introducing an ignition source without required compensatory measures that would ignite the transient combustibles.
- c. Violation of the Hot Work control program that resulted in not posting a required fire watch or a failure of the fire watch to perform his responsibilities.
- d. Violation of the General Employee Training that informs all employees of the requirements of fire protection and how to identify and report fire hazards.
- e. For the rooms described below (i.e., 757.0-A14, 757.0-A15, and 729.0-A6) with automatic suppression and/or detection, a failure of the suppression and/or detection systems.
- f. For the Reactor Buildings, a failure of the Reactor Building entry/exit material control program.
TVA does not consider this to be a credible scenario where a fire of significant magnitude could occur in any of the rooms included in the deviation request. The insignificant quantities of combustible material, lack of ignition sources, controls of transient combustibles, and hot work preclude a significant fire from occurring. There are only three rooms in the deviation request that have in situ combustible loading greater than 5 minutes, and these rooms are provided with automatic suppression and/or detection which would prevent a postulated fire from becoming severe enough to damage any cables or components. Furthermore, it is not a requirement to assume an unrelated single failure (suppression or detection) in combination with a fire.
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ENCLOSURE 1 TVA Responses on NRCs Group 8 RAI Follow-up Questions However, the deviation 2.9 evaluations have been expanded to include potential fire damage to all FSSD cables and equipment located in the room and the effect on continued operation, plant trip, and safe shutdown capability. The evaluations are divided into three sections: (1) redundant components in the room, (2) redundant component located in an adjacent room within the same analysis volume, and (3) other FSSD cables in the room.
Discuss the possibility of room-to-room fire spread, in particular for unrated fire barriers and for adjacent rooms that contain redundant safe shutdown equipment.
TVA Response:
The possibility of room-to-room fire spread has been addressed in each of the rooms of concern.
The possibility of fire spread was addressed from the room of concern into adjacent rooms and from adjacent rooms into the room of concern. This will be documented in the FPR, Part VII, Section 2.9. These evaluations determined that, due to the insignificant quantities of combustible material, lack of ignition sources, robust transient combustible controls and hot work controls programs, and construction of walls, floors and ceilings of the rooms, no credible fire could occur that would propagate from the room of concern into an adjacent room or from an adjacent room into the room of concern. Therefore, the possibility of room-to-room fire spread is extremely low.
For all equipment determined not to be significant ignition sources, identify the basis documents, as references, that support this conclusion.
TVA Response:
The conclusion as to certain components not being significant ignition sources is based on information contained in NUREG/CR-6850. The NUREG is reference 4.1.28 in the FPR, Part II, Section 4.1, Regulatory Documents. In addition, components that are normally de-energized and contain insignificant quantities of combustibles and/or the combustible material associated with the component is separated from a potential ignition source are considered as an insignificant ignition source.
Verify the equipment in Room 676.0-A1 only contains equipment necessary for cold shutdown.
TVA Response:
The Fire Protection Report Deviation 2.9 defines Equipment in regard to an end device such as a motor control center, valve, handswitch, etc. Cable is referring to the electrical power, control and instrumentation circuits.
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ENCLOSURE 1 TVA Responses on NRCs Group 8 RAI Follow-up Questions TVA has confirmed that there is no equipment in Room 676.0-A1 that is required for FSSD (hot or cold) due to a fire in the room. There are cables associated with residual heat removal (RHR) that are necessary to achieve and maintain cold shutdown for an Appendix R fire in the Control Building. The deviation request for Room 676.0-A1 is being removed from the FPR, Part VII, Section 2.9 since these cables are only required for a fire in the Control Building that requires abandonment of the main control room. This change will be reflected in the FPR. The control of ignition sources, insignificant quantities of in situ combustibles, and plant procedures concerning transient combustibles and performance of hot work in the room provide a level of confidence that no fire would occur in Room 676.0-A1 that could damage these cables. Even if a fire could occur and fail these cables, their failure would not result in an impact to FSSD capability.
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ENCLOSURE 2 Fire Protection Commitment
- 1. The fire protection strategy error affects both design calculations and the FPR. This discovery was identified to NRC by telecon on April 11, 2012. TVA expects to complete the reanalysis and submit the revised FPR by April 27, 2012. That submittal will include a description of the strategy error and the resulting impact.
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