ML100470774

Response to Request for Additional Information Request for Exemption from 10 CFR 50, Appendix R, Section Iii.G, Fire Protection of Safe Shutdown Capability

ML100470774
Person / Time
Site:	Peach Bottom
Issue date:	02/12/2010
From:	Cowan P Exelon Generation Co, Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML100470774 (66)

Text

www.exeloncorp.com Kennett Square, PA. 19348 10 CFR 50.12 February 12, 2010 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Peach Bottom Atomic Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-44 and DPR-56 NRC Docket Nos. 50-277 and 50-278

References:

Response to Request for Additional Information Request for Exemption from 10 CFR 50, Appendix R, Section III.G, "Fire Protection of Safe Shutdown Capability" 1.

Letter from P. B. Cowan, Exelon Generation Company, LLC, to U.S. Nuclear Regulatory Commission, "Request for Exemption from 10 CFR 50, Appendix R, Section III.G, 'Fire Protection of Safe Shutdown Capability'," dated March 6, 2009.

2.

Letter from J. D. Hughey, U.S. Nuclear Regulatory Commission, to C. G. Pardee, Exelon Generation Company, LLC, "Peach Bottom Atomic Power Station, Units 2 and 3

- Request for Additional Information Regarding Request for Exemption from 10 CFR 50, Appendix R, Section III.G, 'Fire Protection of Safe Shutdown Capability' (TAC Nos.

ME0855 and ME0856)," dated November 20, 2009.

In Reference 1, Exelon Generation Company, LLC (Exelon) submitted a request for exemption from the provisions of 10 CFR 50, Appendix R, Section III.G, "Fire Protection of Safe Shutdown Capability," for the use of operator manual actions (OMAs) for Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3, in lieu of the requirements specified in Section III.G.2. The NRC reviewed the exemption request and identified the need for additional information in order to complete their evaluation of the exemption request. Draft questions were sent to Exelon to ensure that the questions were understandable, the regulatory basis for the questions was clear, and to determine if the information was previously docketed. On November 12, 2009, and November 13, 2009, teleconferences were held between the NRC and Exelon to further discuss the additional information requested by the NRC. In Reference 2, the NRC formally issued the request for additional information. Attachment 1 to this letter provides a restatement of the questions along with Exelon's responses. Attachment 2 provides fire hazards analyses for the specific fire areas of origin associated with the OMAs in support of the responses to the RAI questions in Attachment 1.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Docket Nos. 50-277 and 50-278 February 12, 2010 Page 2 At the time the original request for exemption was submitted (Reference 1), regulatory guidance concerning the types of OMAs that required exemption from Appendix R,Section III.G.2 had not yet been finalized. In October 2009, Regulatory Guide (RG) 1.189, Revision 2 was issued. RG 1.189, Rev. 2 provides guidance relative to equipment on the hot shutdown success path (Le.,

equipment required to achieve and maintain hot shutdown), versus equipment that is important to safe shutdown. The RG states that OMAs may be credited with mitigating fire-induced operation or maloperation of components that are not part of the protected success path.

Based on this guidance, Exelon has re-evaluated the OMAs that were the subject of the original exemption request and determined that certain of the OMAs are credited with mitigating fire-induced operation or maloperation of components that are not part of the protected success path, and as a result, are not within the scope of Appendix R,Section III.G.2. Therefore, Exelon hereby withdraws these OMAs from the exemption request. The specific OMAs being withdrawn and the reasons for their withdrawal are indicated in Attachment 3 to this letter.

Exelon has determined that the information provided in response to the request for additional information does not impact the conclusions of the original exemption request for those OMAs remaining in the exemption request as stated in Reference 1.

This response to the request for additional information contains no regulatory commitments.

If you have any questions or require additional information, please contact Glenn Stewart at 610-765-5529.

RespectfUlly, lJ~'kt

'{fUK1cUA Pamela B. Cowan Director, Licensing and Regulatory Affairs Exelon Generation Company, LLC : Response to Request for Additional Information : Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas : Withdrawal of Certain Operator Manual Actions from the Exemption Request cc:

USNRC Regional Administrator - Region I USNRC Senior Resident Inspector - PBAPS USNRC Project Manager, NRR - PBAPS S. T. Gray, State of Maryland R. R. Janati, Commonwealth of Pennsylvania w/attachment

ATTACHMENT 1 10 CFR 50.12 Exemption Request Peach Bottom Atomic Power Station, Units 2 and 3 Docket Nos. 50-277 and 50-278 Request for Exemption from 10 CFR 50, Appendix R, Section III.G, Fire Protection of Safe Shutdown Capability" Response to Request for Additional Information

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 1 of 22 Docket Nos. 50-277 and 50-278 ATTACHMENT 1 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION 10 CFR 50, APPENDIX R, SECTION III.G.2 EXEMPTION REQUEST In Reference 1, Exelon Generation Company, LLC (Exelon) submitted a request for exemption from the provisions of 10 CFR 50, Appendix R, Section III.G, Fire Protection of Safe Shutdown Capability," for the use of operator manual actions (OMAs) for Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3, in lieu of the requirements specified in Section III.G.2. The NRC reviewed the exemption request and identified the need for additional information in order to complete their evaluation of the exemption request. Draft questions were sent to Exelon to ensure that the questions were understandable, the regulatory basis for the questions was clear, and to determine if the information was previously docketed. On November 12, 2009, and November 13, 2009, teleconferences were held between the NRC and Exelon to further discuss the additional information requested by the NRC. In Reference 2, the NRC formally issued the request for additional information (RAI). The questions are restated below along with Exelon's responses.

RAI-01 Circumstances for Review Section II of the submittal Attachment contains background information on the proposed OMAs but does not contain a technical justification for the application of special circumstances in accordance with 10 CFR 50.12. Since, according to Section II, it is the licensees position that the protective measures prescribed by III.G.2 represent an unwarranted burden on Exelon and are not necessary to meet the underlying purpose of the rule, provide the relevant details to support this position in response to RAI-01.1 and RAI-01.2 below. The response should demonstrate that defense-in-depth is provided such that operators are able to safely and reliably achieve and maintain safe shutdown capability. Note that it is the NRC staff's position that operator manual actions alone, regardless of their feasibility and reliability, do not meet the underlying purpose of the rule without specific consideration of the overall concept of defense-in-depth that is being applied in a particular fire area.

RAI-01.1:

Provide a technical justification of how the proposed arrangement achieves the underlying purpose of the rule.

RESPONSE

Appendix R,Section III.G.2 requires the following:

Except as provided for in paragraph G.3 of this section, where cables or equipment, including associated non-safety circuits that could prevent operation or cause maloperation due to hot shorts, open circuits, or shorts to ground, of redundant trains of systems necessary to achieve and maintain hot shutdown conditions are located within the same fire area outside of primary containment, one of the following means of ensuring that one of the redundant trains is free of fire damage shall be provided:

a. Separation of cables and equipment and associated non-safety circuits of redundant trains by a fire barrier having a 3-hour rating. Structural steel forming a part of or

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 2 of 22 Docket Nos. 50-277 and 50-278 supporting such fire barriers shall be protected to provide fire resistance equivalent to that required of the barrier;

b. Separation of cables and equipment and associated non-safety circuits of redundant trains by a horizontal distance of more than 20 feet with no intervening combustible or fire hazards. In addition, fire detectors and an automatic fire suppression system shall be installed in the fire area; or

c. Enclosure of cable and equipment and associated non-safety circuits of one redundant train in a fire barrier having a 1-hour rating, In addition, fire detectors and an automatic fire suppression system shall be installed in the fire area.

The underlying purpose of the rule is to accomplish safe shutdown in the event of a fire and maintain the plant in a safe shutdown condition. The operator manual actions in this exemption request are required because not all required fire protection and/or suppression requirements in Appendix R,Section III.G.2 are met as described in Attachment 2 nor are they practical or necessary to achieve the underlying purpose of the rule.

Following the guidance provided in NUREG-1852, "Demonstrating the Feasibility and Reliability of Operator Manual Actions in Response to Fire," Exelon performed a feasibility review of the 10 CFR 50, Appendix R, Section III.G.2, operator manual actions needed to safely shutdown the plant in the event of a postulated fire. Exelon's evaluation provided in the original submittal (Reference 1) concludes that operator manual actions required for achieving and maintaining hot shutdown conditions are feasible, reliable, and not affected by environmental conditions associated with fires in the affected fire areas. In addition, the equipment needed to implement operator manual actions remains available and the fire areas remain accessible during or following the event. The operator manual actions are directed by plant procedures, and the operators are trained in the use of the procedures.

The evaluation also concluded that staffing is adequate to perform the manual actions.

Demonstrations have shown that adequate time is available to perform the manual actions, and that time margin is available to account for uncertainties that may arise during a fire event. The evaluation found that the operator manual actions are feasible and reliable.

Moreover, initiating fire areas/zones have low combustible loading, consisting primarily of cable insulation. Therefore, fires will be slow to develop, which will provide further margin to cable failure unaccounted for in the aforementioned evaluation. The operator manual actions covered by the exemption request are similar to activities performed by plant operators as part of their normal work assignments, and as a result, are straightforward.

Likewise, PBAPS adheres to the principles of fire protection defense-in-depth. The principles of fire protection defense-in-depth are:

to prevent fires from starting, to detect rapidly, control, and extinguish promptly those fires that do occur, and to provide protection for structures, systems and components important to safety so that a fire that is not promptly extinguished by the fire suppression activities will not prevent the safe shutdown of the plant.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 3 of 22 Docket Nos. 50-277 and 50-278 PBAPS has a Fire Protection administrative control program that addresses controls on ignition sources, hot work activities, in-situ and transient combustibles, and fire system impairments. These controls are reviewed by NRC Regional Inspectors, insurance inspectors and Nuclear Oversight auditors. The administrative control program is described in the PBAPS Fire Protection Program (FPP), which is incorporated into the Updated Final Safety Analysis Report (UFSAR).

PBAPS has fire detection in many areas of the plant. Plant areas with fire detection have been described to the NRC in prior correspondence and the locations are currently summarized in the PBAPS FPP. Those rooms without fire detection which contain safety related equipment, or safe shutdown cables or equipment have been addressed by approved exemption requests where necessary.

Fire suppression systems are installed in plant areas with significant fire hazards, such as lube oil. Suppression systems have also been installed in areas with one-hour barrier walls and one-hour rated electrical raceway encapsulation. The locations of fire suppression systems have previously been described to the NRC in correspondence and are currently summarized in the PBAPS FPP. Those rooms without fire suppression systems which contain safety related equipment, or safe shutdown cables or equipment have been addressed by approved exemption requests where necessary.

PBAPS has been divided into fire areas for Appendix R compliance purposes, as described in the PBAPS FPP. Three-hour fire barriers are normally used to provide fire resistive separation between adjacent fire areas. Some Fire Areas contain a number of individual rooms which may be separated by non-fire rated boundaries. For the purposes of analysis, subdivision of fire areas into individual rooms takes into consideration the physical boundaries which exist between rooms within the same fire area. Reasonable assurance that a fire will not propagate from one room to another is provided in the plant fire hazards analysis by passive and active fire protection features.

In some cases, rated barriers with a fire resistance rating of less than three hours are credited but exemptions have been approved, fire detection or suppression systems are provided or engineering evaluations have been performed in accordance with Generic Letter 86-10. The PBAPS FPP provides the rating of the fire barriers separating adjacent fire areas. Information regarding the specific fire protection defense-in-depth features in each of the initiating fire areas addressed by the exemption request was discussed in the original exemption request and is described in more detail in Attachment 2. Note: the separation of fire areas is not the issue with the OMAs, which are necessary due to assumed damage within the fire area itself. Only exemptions or evaluations associated with separation within the fire area or fire suppression/detection systems within the fire area will be referenced.

Appendix R continues to be satisfied by the requested exemption since the existing analysis described in the exemption request and in this response to request for additional information demonstrates that the plant can achieve safe shutdown in the event of a single fire and be maintained in a safe shutdown condition, and therefore, provides an equivalent level of safe shutdown capability through the combination of defense-in-depth fire protection features and the use of the manual actions. Therefore, the underlying purpose of the rule, to achieve safe shutdown in the event of a postulated fire, is met using the defense-in-depth and operator manual actions described in the exemption request.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 4 of 22 Docket Nos. 50-277 and 50-278 RAI-01.2:

Provide an analysis that substantiates the claim of unwarranted burden and demonstrates that the hardship or other costs associated with the modifications noted as being required to achieve compliance are significantly in excess of those contemplated at the time the regulation was adopted, or are significantly in excess of those incurred by others similarly situated.

RESPONSE

As previously discussed, the underlying purpose of Appendix R,Section III.G.2 is to ensure that one train of systems necessary to achieve and maintain safe shutdown capability remains free from fire damage. In responding to this RAI, Exelon has reassessed the need for a number of manual actions and has withdrawn specific actions from the exemption request. The underlying purpose of the rule continues to be satisfied by the use of the remaining operator manual actions described in the exemption request.

If these remaining manual actions are not used to achieve safe shutdown in the event of a fire, modifications to: 1) provide additional fire suppression systems, detection systems, or fire barriers, or 2) reroute cables or wrap cables, that involve issues such as accessibility, dose, structural interferences, design limitations, ampacity derating, etc., would be required to achieve compliance with Appendix R,Section III.G.2. The costs associated with engineering, procurement of material, fabrication and installation of the aforementioned modifications represent an unwarranted burden on Exelon with negligible increase in safety compared to the intended costs to implement the requirements of Appendix R,Section III.G.2 when the rule was originally put into effect.

Regardless of the burden to Exelon, as described in the response to RAI-01.1, when considering the combination of defense-in-depth and the feasibility and reliability of the OMAs, the underlying intent of the rule is achieved.

Therefore, based on the discussion above, special circumstances are present that warrant granting an exemption to 10 CFR 50, Appendix R, Section III.G.2.

RAI-02 Ensuring That One of the Redundant Trains Is Free of Fire Damage Section II of the request asserts that the OMAs discussed in the request provide assurance that one train of systems necessary to achieve and maintain hot shutdown remains available in the event of a fire.Section II.C.1 contains a description of each of the OMAs and the time required to perform them but, does not state whether or how one of the redundant trains in a particular fire area is maintained free of fire damage.Section II.C.3 states that the analysis assumes that all potential fire damage identified for a fire area occurs instantaneously.

The method described in the request appears to demonstrate safe shutdown capability independent of the fire area of origin consistent with III.G.3, yet the request is for an Exemption from the requirements of III.G.2. III.G.2 specifically states that measures must be taken to ensure that one of the redundant trains remains free of fire damage and provides three options for accomplishing this. The use of OMAs is not explicitly included as a means of compliance in III.G.2.Section III.G.3 of Appendix R addresses alternative or dedicated shutdown capability

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 5 of 22 Docket Nos. 50-277 and 50-278 independent of the fire area of origin and establishes a series of requirements to achieve and maintain safe shutdown capability.

RAI-02.1:

Confirm and state whether an Exemption from III.G.2 requirements is the appropriate request, since safe shutdown capability is provided independent of the fire area of origin.

RESPONSE

These areas have been considered III.G.2 since the initial Appendix R submittal (letter dated September 16, 1983, from V. S. Boyer, PECo, to D. G. Eisenhut, NRC). The PBAPS Fire Safe Shutdown (FSSD) methodology initially assumes that all equipment in a fire area is lost to determine which shutdown method remains available (HPCI, RCIC, ADS/LPCI or ADS/Core Spray) for both units. The surviving shutdown method is identified. Initially, certain OMAs were identified and in other cases, separation using encapsulation was used.

As part of the Thermo-lag resolution project, the need for encapsulation was revisited.

While in most cases the Thermo-lag was upgraded or replaced, several instances in which a straightforward manual action could be performed in lieu of an upgrade were identified and implemented. With the exception of these individual actions, shutdown can be performed from the control room.

The OMAs that are the subject of the exemption request are not part of a methodology to shutdown the plant from outside the control room using dedicated or alternate shutdown panels. Each of the OMA are taken to permit continued shutdown of the plant from the main control room.

RAI-02.2:

State the specific requirements of III.G.2 that are not met for each of the requested exemptions. For example, a lack of fire barriers, spatial separation, automatic suppression, etc..

RESPONSE

This information is provided in the fire hazards analyses for the individual OMAs in.

RAI-02.3:

Provide a summary of the plant specific features that compensate for the lack of III.G.2-required features, identified in RAI-02.2, for each of the requested exemptions. For example, note any enhanced defense-in-depth measures such as a lack of ignition sources and/or combustibles, more robust and/or supplemental detection and suppression systems and other physical or administrative controls.

RESPONSE

When RIS 2006-10 was issued PBAPS entered all the OMA into the corrective action program. At that time, based on the straightforward nature of the actions, it was determined that the existing manual actions themselves were feasible and constituted adequate compensatory actions. NRC Triennial Fire Protection Inspections in 2003, 2006 and 2009 reached the same conclusion. Additional details regarding defense-in-depth measures such

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 6 of 22 Docket Nos. 50-277 and 50-278 as suppression, detection, ignition sources and combustibles in the initiating fire area for each OMA are provided in the fire hazards analysis in Attachment 2.

RAI-02.4:

III.G.2 requirements provide defense-in-depth such that operators are able to safely and reliably achieve and maintain hot shutdown capability from the control room. Provide a technical explanation that justifies how the proposed methods will result in a level of protection that is commensurate with that intended by III.G.2.

RESPONSE

The initial exemption request provided a detailed review and comparison of the PBAPS OMA and NUREG-1852, which provides the NRC position on what constitutes feasible and reliable OMAs. This review remains valid. The PBAPS OMAs are straightforward and consistent with actions equipment operators normally perform in their daily duties. During the 2009 NRC Triennial Fire Protection Inspection at PBAPS, the lead inspector performed a walkdown of each of the OMAs addressed in the exemption request and found them all to be simple in nature, with ample time to perform the actions. In addition, PBAPS performed demonstrations using the simulator to show that not only were the performance times accurate, but that diagnosis times including those for prompt actions were achievable and repeatable. This was the reliability piece described by NUREG-1852. Additional details regarding defense-in-depth is provided in the fire hazards analysis in Attachment 2. The combination of the reliability and feasibility of the OMAs in conjunction with the defense-in-depth features described in the fire hazards analysis meets the underlying intent of the rule in assuring the ability to safely shutdown the plant following a fire.

RAI-03 Other Evaluations Fire areas may have other exemptions or engineering evaluations that affect fire protection systems or safe shutdown capabilities.

RAI-03.1:

Provide a discussion of any other exemptions or evaluations that impact this request in any way and provide a justification for why such impact should be considered acceptable.

RESPONSE

A complete discussion of exemptions or evaluations applicable to each fire area is maintained in the PBAPS FPP, which is incorporated into the UFSAR. Where an exemption request or evaluation impacts the fire hazards analysis for separation of cables within the fire area, or detection and suppression, the exemption or evaluation is addressed in the fire hazards analysis for that specific action provided in Attachment 2. Exemptions or evaluations that address fire area boundaries are based on assuring that the boundary is adequate for the hazard, and therefore are not addressed in this response unless there is an impact to the OMA being addressed.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 7 of 22 Docket Nos. 50-277 and 50-278 RAI-04 Standards and Listings for Systems and BarriersSection II.B of the Attachment notes that several areas are equipped with various fire detection and suppression systems. However, the request does not state whether the systems have been designed and installed in accordance with recognized design standards.

RAI-04.1:

Where fire protection features such as detection and suppression systems and fire rated assemblies are installed, describe the technical basis for such installations including the applicable codes, standards and listings.

For example:

Section II.B.1 of the Attachment states that Fire Area 2 is equipped with a CO2 system, pre-action sprinklers and wet pipe sprinklers. State whether these systems have been installed and maintained in accordance with a particular design standard or basis, e.g. National Fire Protection Association 13: Standard for the Installation of Sprinkler Systems, 1985 Edition.

Response: Section II.B.1 of the Attachment provides generic information regarding fire protection features for the entire fire area.

Fire Area 2, as stated in the referenced section contains numerous rooms separated by heavy concrete walls and floor/ceiling assemblies.

A description of fire protection features in the rooms where the cables of concern for the OMA are actually routed is provided in the fire hazards analysis for the applicable OMA.

Section II.B.2 of the Attachment states that Fire Area 4 is equipped with full area smoke detection that actuates a pre-action sprinkler system.

State whether the detectors have been installed and maintained in accordance with a particular design standard or basis, e.g. National Fire Protection Association 72: National Fire Alarm Code, 1985 Edition.

Response: As discussed in Attachment 3, the OMAs for Fire Area 4 have been withdrawn from the exemption request.

Section II.B.4 of the Attachment states that Fire Area 6S is subdivided into various rooms and floors by heavy concrete barriers. State what the fire rating is for the barriers as well as any penetrations and whether they are designed and installed in accordance with a particular standard or listing. Also state whether fire areas are separated from adjacent fire areas and the rating and integrity of such barriers.

Response: The heavy concrete barriers within the fire area are not considered fire rated barriers for the purposes of separation, since the barriers are within the same fire area. If those barriers provide separation between trains that require an OMA addressed by the exemption, then a description of that exemption will be provided in the applicable fire hazards analysis in Attachment 2. The ratings for fire

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 8 of 22 Docket Nos. 50-277 and 50-278 area boundaries between fire areas are not the subject of this exemption, and therefore, are not provided.

Section II.B.4 of the Attachment states that Fire Area 6S has a water curtain type open head sprinkler system installed along the west side of the reactor building. State whether this system has been installed and maintained in accordance with a particular design standard or basis, e.g. National Fire Protection Association 13: Standard for the Installation of Sprinkler Systems, 1985 Edition, and how it is activated Response: There is no NFPA code that applies to water curtain systems in terms of head spacing and location. This system provides separation between two fire areas within the Reactor Building on elevation 135. The separation of these two Fire Areas (6S and 6N) is not part of the OMA exemption request, since the OMA is performed in Fire Area 33 which is in a different building. This system (and a similar water curtain separating FA 13N from 13S in the Unit 3 Reactor Building) were approved by the NRC in an SER dated March 13, 1985.

The current design of these systems is described in the PBAPS FPP, Sections 2.10, 5.3.5, 5.3.6, 5.3.10 and 5.3.11. This system is automatically actuated by heat detection.

RESPONSE

Where fire protection features such as detection and suppression systems and fire rated assemblies are addressed in the fire hazards analysis provided in Attachment 2, the system is described as code compliant or not code compliant.

RAI-04.2:

Provide a technical justification for any deviations from codes, standards and listings by independent testing laboratories in the fire areas that could impact this evaluation.

RESPONSE

Where a fire protection system or barrier is addressed in the fire hazards analysis in, the system is described as code compliant or not code compliant.

RAI-04.3:

Provide a technical justification for any non-rated fire protection assemblies.

RESPONSE

Where a non-rated assembly is described in the fire hazards analysis in Attachment 2, information is provided. In most cases, the non-rated assembly is abandoned Thermo-lag, that remains intact on conduits and junction boxes. The Thermo-lag originally installed at PBAPS was intended to have a three-hour fire resistance rating. Subsequent testing found this Thermo-lag material and installation method capable of approximately a one-hour rating. As part of the Thermo-lag resolution effort, some of the existing Thermo-lag was upgraded to restore the three-hour rating, or in other cases was reviewed and confirmed to still provide at least a one-hour rating, and suppression and detection were added to the

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 9 of 22 Docket Nos. 50-277 and 50-278 area where the one-hour rated Thermo-lag was routed. No specific fire resistance rating is being given for the abandoned Thermo-lag; however, since this Thermo-lag was constructed to the same standard as other Thermo-lag which has been shown to provide an acceptable one-hour rating, it is reasonable to conclude that some level of protection is still provided to the cable within the encapsulation. For those cables that remain encapsulated in abandoned Thermo-lag in areas where automatic suppression is provided it is reasonable to conclude that the protection provide by the abandoned Thermo-lag will last until the actuation of the suppression system.

RAI-05 Time and Sequence AssumptionsSection II.C.3 states that the analysis assumes that all potential fire damage identified for a fire area occurs instantaneously at the point of plant shutdown and that a 30-minute diagnosis time has been assumed for the OMAs except for those classified as prompt.Section II.C.1 contains a discussion of the amount of time required to perform the OMAs versus the time available. This section also indicates that margins of safety range from 6 minutes to 113 minutes.

The request lacks a detailed description of the series of events that may occur prior to initiating the OMA procedures. For example,Section II.B of the Attachment states that Action C is a prompt action, which is comprised of a series of 6 tasks. This section goes on to state that Action C requires 15 minutes to perform with an assumed available time of 25-minutes but does not describe whether the procedure is initiated immediately upon activation of the fire detection system in Fire Area 2, or upon confirmation of a fire in that area, or upon some other form of indication. For this example, if the operators were to take more than 10 minutes to diagnose or confirm the fire and begin the procedure and the redundant components were damaged upon the onset of the fire, the total time to complete the procedure would exceed the 25-minute time limit. Therefore, sufficient time would not be available to assure safe shutdown.

RAI-05.1:

Considering that a 30-minute diagnosis time is assumed for the non-prompt actions to account for challenges, unknowns, or delays, provide a justification that similar challenges are adequately accounted for in the prompt action timelines.

RESPONSE

Section II.C.3.a.1 of the exemption request provides information as to how a prompt action would be handled. In order to ensure a rapid response to a "prompt" action, procedural guidance is provided in both the fire response procedure and the individual fire area specific Fire Guides (T-300 series). Off Normal procedure ON-114, "Actual Fire Reported in the Power Block, Diesel Generator Building, Emergency Pump, Inner Screen or Emergency Cooling Tower Structures," is immediately entered upon confirmation of a fire condition. A confirmed fire occurs when there is a visual report of smoke or fire, or a plant fire alarm accompanied by an equipment related alarm from the same area. This procedure notes that "prompt" actions exist for some fire area and Attachment 3 of this procedure lists the prompt actions. In addition, this procedure directs immediate entry into the applicable T-300 Fire Guides for both units and execution of the applicable T-300 fire guides concurrently. T-300 Fire Guides that contain "prompt" actions identify the "prompt" actions as a bolded note at the beginning of the document. Therefore, there is no delay in initiating the "prompt" action if it is required. Control room personnel and plant equipment operators have been trained

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 10 of 22 Docket Nos. 50-277 and 50-278 on the need to immediately initiate "prompt" actions. The focus on the need to initiate "prompt" actions placed in the fire response procedure and each applicable Fire Guide ensures that the operator performing the "prompt" action will have adequate time to perform the action. The prompt actions addressed by this exemption request are pulling fuse blocks in a switchgear room well separated from the fire location, and installing a test plug in a cabinet in the cable spreading room, also well separated from the fire location.

Section II.C.3 states that operators will know a fire condition exists from the onset of the event and that they will be aware of the location and size of the fire based on reports from the fire brigade.

RAI-05.2:

Describe the circumstances and assumptions needed to enter the OMA procedure. For example, describe the amount of time, and the technical basis, that has been assumed for detection and assessment of a postulated fire as well as the expected plant response to a postulated fire.

RESPONSE

ON-114, "Actual Fire Reported in the Power Block, Diesel Generator Building, Emergency Pump, Inner Screen or Emergency Cooling Tower Structures," directs control room personnel in the first two steps to:

1)

Monitor plant parameters, indications, and lineups for abnormal conditions on both units.

2)

Enter the T-300 Fire Guide for both units and execute concurrently.

Areas of the plant with safety related or safe shutdown cables and equipment that contain significant quantities of combustible materials are provided with fire detection. Therefore, an exposure fire of a sufficient magnitude that could damage plant equipment would be rapidly detected. A small or smoldering fire is not capable of affecting the magnitude of cables or equipment that are assumed lost by the safe shutdown analysis, and it is unlikely that a shutdown would be required for a small or smoldering fire, or that the manual actions in this exemption request would be required for a fire of this small size.

RAI-05.3:

Either provide an analysis and/or technical justification that demonstrates that the ability to detect a fire is sufficient to provide notification of a postulated event coincident to or before damage to the redundant trains occurs; or provide an analysis and/or technical justification to evaluate scenarios where the redundant components are damaged, before a fire has been detected.

RESPONSE

The PBAPS Appendix R analysis is based on the assumption that a fire area is lost at the start of the event. The damage occurs instantaneously, and is concurrent with the time the fire alarm is received. A fire of sufficient magnitude to cause equipment damage will create smoke and heat conditions that will provide a fire alarm. Fires that would be postulated to create heat release rates sufficient to damage cables will produce smoke and heat of a magnitude to promptly actuate smoke detection in the vicinity of the cable subject to fire

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 11 of 22 Docket Nos. 50-277 and 50-278 damage. The two types of fires identified in the attached fire hazards analyses that could damage cables are:

1)

Failures of high voltage electrical equipment (switchgear, load centers and MCCs). Failures of these high voltage components will be immediately identified in the control room due to associated alarms on the loss of components and electrical supplies.

2)

Lube oil or fuel oil fires associated with an emergency diesel generator or Recirculation Pump MG set, create high heat and smoke conditions that will be immediately identified by installed detection systems. These fire scenarios also involve the catastrophic failure of a diesel or MG set; the loss of this equipment will be immediately obvious in the control room due to equipment alarms.

The loss of certain equipment results in a control room alarm. Receipt of a plant equipment alarm alerts the control room of the condition. A subsequent plant fire alarm provides documentation of a fire condition. PBAPS procedures FF-01, "Fire Brigade," and ON-114 provide direction that a fire condition exists when a plant equipment alarm and a fire alarm are received. ON-114 is entered upon a confirmed plant fire which is a report of a fire from the field or a detection alarm in conjunction with a plant equipment alarm from the same area. ON-114 directs immediate entry into the Fire Guide for the affected fire area. OMAs that are considered prompt are identified in both ON-114 and in the applicable Fire Guide as an item requiring immediate attention.

RAI-06 Ignition Sources and Combustible Fuel Load Section II.B includes a description of the combustible fuel load in each of the fire areas in question and rates them as LOW, MEDIUM or HIGH. Items such as cable insulation, lube oil, silicon rubber and Class A materials are stated as being present in many of the fire areas.

RAI-06.1:

Provide critical details and/or assumptions regarding the fire hazards for each fire area included in the request. This information may include, but is not limited to:

The number, type and location of potential ignition sources.

The number and types of equipment that may exhibit high energy arcing faults, and the relationship between this equipment and any secondary combustibles.

The quantity of cables and other secondary combustibles and their relationship to potential ignition sources.

The cable type, e.g., thermoplastic or thermoset. If thermoplastic cables are used, provide a discussion of self-ignited cable fires.

Ratings for cables, e.g., IEEE-383, etc. If not rated, justify why fire spread would be assumed to be slow.

Controls on hot work and transient combustibles in the area, and the proximity of secondary combustibles that could be impacted by a transient fire.

Dimensions of the rooms including ceiling heights.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 12 of 22 Docket Nos. 50-277 and 50-278

RESPONSE

This information is provided in the fire hazards analyses for the individual OMAs contained in Attachment 2 RAI-07 Fire Area Proximity and AccessSection II.B of the attachment describes each fire area and includes statements about the nature and/or rating of the fire area boundaries. However,Section II.B does not mention whether openings and penetrations exist and maintain the integrity of the rated barriers. The fire rating of the barriers is also not stated.Section II.C.1 does note that many of the fire areas have separate ventilation systems but does not discuss how and when these systems activate and whether they have been designed to transport products of combustion without causing additional damage to equipment or relocating the smoke to other fire areas.

RAI-07.1:

For adjacent fire areas or where operators will pass within close proximity of the fire affected area included in the request, provide a technical justification that demonstrates that a fire in the fire area of fire origin would not impact the performance of the OMA.

RESPONSE

This information is already provided in the exemption request in both Section II.C.1 and Section II.C.3.c.4 RAI-07.2:

State whether identified ventilation systems are used for smoke evacuation or fire brigade operations and provide a justification for the systems' capabilities.

RESPONSE

The fire brigade may use the installed ventilation system for smoke removal if it remains operable or they may use manual smoke removal equipment. Actions B, C, D, G, H, J, K, T, U, V, X, Y, BB and CC have a ventilation system separate from the ventilation system for the area where the manual action is performed. For these areas the use of the ventilation system in the fire affected area for smoke removal will not impact the access to or performance of the manual action. Actions M, R and S involve fire areas in which the OMAs are performed in areas with the same ventilation system. Details of this ventilation arrangement are provided in Section II.C.3.c.4 of the original exemption request. These three rooms are either switchgear or battery rooms which have a common ventilation system. Each of these three rooms is small (525 sq. ft), and smoke will likely be vented into the Turbine Building, which has a sufficient volume to dilute the smoke. The OMA for each of these fire areas are 60-minute actions so there will be adequate time to provide ventilation prior to the time when entry has to be made into the other switchgear rooms.

PBAPS has performed fire brigade drills in the switchgear rooms with a specific objective to have the smoke vented using smoke ejectors to permit access to the other switchgear rooms for operator actions. Based on the small size of the rooms and the amount of time available before the action must be performed, smoke conditions in the switchgear room where the OMA is performed will not prevent the action from being performed on time.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 13 of 22 Docket Nos. 50-277 and 50-278 RAI-08 Fire ScenariosSection II.C.1 describes each of the OMA procedures but does not state what fire scenarios have been considered for the postulated events. Also, the request includes discussions of equipment that may be available, but does not include a discussion of whether that equipment would be affected by the postulated events.

For example: For Fire Area 50, no information is provided to describe the spatial relationship between the combustible materials (i.e. cables, lube oil, thermo-lag etc.) and the safe shutdown equipment located in the fire area. Also, missing is a discussion of the relationship between the two redundant trains in the area and whether they are located such that a single fire event could damage both buses.

Note, that these questions are distinct from the RAI addressing Ignition Sources and Combustible Loading (RAI-06), which is generally focused on the combustibles in an area, whereas, this RAI addresses the specific relationship between ignition sources, combustibles and the redundant trains or other equipment that may be useful in assuring safe shutdown.

RAI-08.1:

For each OMA included in this request, describe the in situ and transient fire hazards (ignition potential and combustibles) in the fire area that have the potential to affect the redundant trains. Provide a description of the proximity of the redundant train equipment to in situ hazards and the spatial relationship between the redundant trains in the fire area such that if they are damaged, manual actions would be necessary.

RESPONSE

This information is provided in the fire hazards analyses for the individual OMAs in.

RAI-08.2:

Provide a discussion of equipment that may be available and would provide an additional margin of safety. For example, in the description for Action A, the allowable time is based on no high-pressure injection sources being available.

The response for Action A to this RAI should include a discussion of the fire scenarios that would cause failure of the high-pressure injection sources for the postulated fire scenarios.

RESPONSE

The PBAPS FSSD methodology initially assumes that all equipment in a fire area is lost to determine which shutdown method remains available (HPCI, RCIC, ADS/LPCI or ADS/Core Spray) for both units. Systems that are not specifically analyzed are also assumed to be lost (e.g., Feedwater, Condensate, CRD, Instrument Air, etc.). The surviving shutdown method is identified within the safe shutdown analysis calculations. Documentation of the systems that did not survive or that have not been specifically analyzed is not maintained; however, based on general plant layout features, power supply redundancy, diversity, etc., it is clear that an additional margin of safety is available, both in terms of additional unanalyzed equipment that could be used to achieve safe shutdown, and in terms of additional time margin for the operator actions contained in this exemption request.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 14 of 22 Docket Nos. 50-277 and 50-278 The PBAPS FPP, Sections 5.2, 5.2.1, and 5.2.2, describe numerous diverse means that exist to achieve and maintain hot shutdown at PBAPS. As described in FPP, Section 5.2.1, under normal circumstances the feedwater and condensate system may be used to provide reactor inventory control, and the turbine bypass valves may be used to provide pressure control. This equipment is not included in the safe shutdown analysis and supporting calculations, due to not being part of one of the four shutdown methods discussed in FPP Section 5.2.2; however, the following general observations may be made regarding the defense-in-depth associated with these systems:

After the turbine-generator has been tripped and all control rods inserted into the reactor core during the course of a normal shutdown and cooldown, reactor decay heat and sensible heat is removed by bypassing main steam to the condenser. Heat is removed from the condenser by the circulating water system and rejected to the atmosphere by the cooling towers. Makeup water is supplied to the reactor vessel by the condensate and feedwater system, taking suction on the condenser hotwell. When the reactor has been depressurized below a nominal 75 psig, the RHR system is initiated in the normal shutdown cooling mode of operation. In this mode, reactor water is circulated through the RHR heat exchangers, where it is cooled by the HPSW system. Heat is rejected to the environment by discharging water from the HPSW system to the river. The reactor vent valves are opened when reactor pressure reaches atmospheric.

If malfunctions due to the effects of a fire occur in any of the systems that are normally used to achieve reactor shutdown with balance of plant cooling systems available, one of the shutdown methods described in Section 5.2.2 will be used to complete the shutdown.

A qualitative discussion is provided below, identifying significant conservatisms, as well as the inherent defense in depth of the PBAPS capabilities for achieving safe shutdown.

Principal components of the feedwater, condensate, main turbine bypass valves, and circulating water system are primarily located in the turbine building or circulating water pump house. Power supplies to this equipment are primarily provided by 13kv busses in the turbine building, which are then fed from 13kv switchgear in the startup switchgear buildings (external structures outside the power-block). The 13kv switchgear located in the turbine building are in separate fire zones from the principal feedwater and condensate components, thereby providing a high degree of assurance that credible failures of the feedwater or condensate pumps would not impact the 13kv switchgear and vice versa.

Also, for reliability purposes, feedwater and condensate pumps are provided with diverse power supplies, such that loss of a single 13kv switchgear would not result in an immediate total loss of feedwater to the reactor. By virtue of the above systems being located in the turbine building, and the diversity of power supplies provided for reliability purposes, there is reasonable assurance that for fires in the areas involving this exemption request, the feedwater, condensate, circulating water, and main turbine bypass valves may be used. If at any time during the post-fire plant shutdown, one or more of these systems becomes unavailable, shutdown would then proceed using safety-related systems, including post-fire safe shutdown methods A, C, and B, as described in FPP section 5.2.2.

The existing fire safe shutdown analysis conservatively assumes that in one instant, all fire damage occurs, all BOP cooling systems are lost, and only one of the credited shutdown

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 15 of 22 Docket Nos. 50-277 and 50-278 methods is available. These conservative assumptions drive many performance and time requirements within the safe shutdown analysis. The particular parameters that are of interest to this exemption request and the defense in depth associated with the parameter are discussed further below:

Assumed instantaneous loss of feedwater drives the need to establish RPV injection within approximately 25 minutes. This sets the time limit to establish AC power for some fire areas (where low-pressure AC injection systems are credited), as well as the time limit to satisfy the low-pressure permissive for RHR.

Assumed instantaneous loss of the condenser as a heat sink drives the need to establish suppression pool cooling within approximately 150 minutes. This sets the time limit to establish AC power or align suppression pool cooling for some fire areas.

Significant cycling of large DC motors associated with the HPCI and/or RCIC systems is a significant contribution to the duty cycle calculation for the safeguard batteries, to support the conclusion that operator actions to restore power to the battery chargers will not be required for at least one hour. This sets the time limit to establish AC power and/or restore battery chargers for some fire areas.

Given the location of the principal components of the feedwater, condensate, circulating water, and main turbine bypass valve systems, there is reasonable assurance that for fires in the areas involving this exemption request, these systems would remain available.

Furthermore, Industry and NRC cable fire testing has demonstrated that even during significant fires, cable failures take some time to develop. This provides additional assurance that as a minimum, the feedwater, condensate, circulating water, and main turbine bypass valves would remain available for the early portions of any fire event at the station. This is important in establishing significant defense-in-depth, due to the rapid decrease in core decay heat output in the first few minutes after a reactor shutdown.

The safe shutdown analysis assumes this initial post-scram decay heat contributes to boil-off, thereby driving the 25-minute milestone for restoring RPV injection.

Proper functioning of feedwater for even a short period of time post-scram would significantly extend the time needed to establish RPV injection with a safe shutdown system.

The safe shutdown analysis assumes that all decay and sensible heat is rejected to the primary containment, ultimately driving a rise in torus temperature and necessitating the initiation of RHR suppression pool cooling in approximately 2.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. If main turbine bypass valves remained operable, turbine-driven feedwater pumps remained operable, or other nuclear steam loads remained in services (e.g.,

steam seals, SJAE, etc.), the amount of heat transferred to containment would be significantly reduced or eliminated, significantly delaying the need to establish suppression pool cooling.

The battery duty cycle calculations that support the safe shutdown analysis assume that the HPCI and RCIC systems cycle on and off multiple times, automatically controlling RPV water level, and that no operator action is taken to secure or throttle them to minimize their cycling. Cycling the large DC motors and DC valves within these systems has a significant impact on the battery capacity calculation. Proper function of feedwater for even a short period of time post-scram would prevent the

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 16 of 22 Docket Nos. 50-277 and 50-278 automatic initiation of HPCI or RCIC on low level, and minimize the number of system cycles that might occur later in the event if feedwater is eventually lost (less system cycles due to lower decay heat later in the event).

Based on the above, it is evident that for most fire areas, the BOP cooling systems are likely to remain available. If the BOP cooling systems were initially available, but lost even a short time later, the short-term availability of BOP cooling systems would result in the significant relaxation of completion times for the manual actions being requested, or may eliminate their need, depending on the extent of time the BOP cooling systems were available prior to their loss.

RAI-09 Travel and Performance Time Calculation RAI-09.1:

Section II.C.1 states that Action U requires eight minutes travel and performance time for restoration of a single bus and that there are a total of four buses to be restored. This would result in a total of 32 minutes (4 x 8) for the travel and performance time but the request states 26 minutes. The same mathematical statement is made for Action V. Confirm how much time has been assumed for restoring the buses and provide the correct calculation.

RESPONSE

The estimated time to perform all of the activities in Action U is correctly stated as 26 minutes. The travel and action time for the first activity is 8 minutes based on travel time from the control room. The subsequent travel is between adjacent switchgear rooms, and the travel and action times for the remaining activities are 6 minutes each. The total time of 26 minutes for all four buses is calculated as follows: 8 minutes plus 18 minutes (3 X 6 minutes).

RAI-09.2:

For Action GG, it is noted that the action requires the operator to obtain and use a plug-in test switch located outside the control room but does not state whether this time has been accounted for in the performance time. State whether this time is included in the 7-minute travel and performance time and sate the total time required to perform the action.

RESPONSE

As discussed in Attachment 3, this action has been withdrawn.

RAI-10 Fire Retardant Insulation Section II.B.1, et al, of the Attachment states that all exposed cables have fire retardant insulation, but does not describe the quality or certification of the fire retardant insulation.

RAI-10.1:

Provide a description of the relevant technical information regarding the performance of the insulation and the technical basis for it being considered fire retardant. For example include cable jacket and insulation construction, thermoset or thermoplastic; standards (IEEE 383, or others); and the manufacturer, product name, installation standard, and deviations from the standard (for applied coating), if applicable.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 17 of 22 Docket Nos. 50-277 and 50-278

RESPONSE

The type of cable used at PBAPS is described below as stated in the PBAPS Fire Protection Plan (FPP), Section 3.1.2, "Explanatory Notes for Comparison to Branch Technical Position APCSB 9.5-1." This information was also noted in the PBAPS Fire Protection Safety Evaluation Report dated May 23, 1979.

The cable construction used for control and power circuits consists of cross-linked polyethylene insulation with a flame retardant neoprene jacket. The flame test standard for cables, IEEE-383-1974, was not in effect at the time these cables were initially purchased and installed. These cables were, however, required to pass a special flame-resistance test detailed in the purchase specification. This test is essentially the oily rag test outlined in IEEE-383-1974. Therefore, the power and control cables used at PBAPS are capable of passing IEEE-383-1974.

Some cables are jacketed with polyvinyl chloride (PVC). These are cables that are used for low-level instrument signals. These cables are predominately routed in trays dedicated to instrument cables. Less that 0.3 percent (by volume) of the cables in all the safeguard trays are jacketed with PVC.

All new cables installed at PBAPS are qualified to IEEE-383.

In addition, Fire Area 26 is described as having cable insulation, but not fire retardant insulation.

RAI-10.2:

Provide a detailed description of the different types of cable insulation used for different fire areas.

RESPONSE

See response to RAI-10.1. Cable used at PBAPS is addressed by that response.

RAI-11 Total Estimated Time Section II.C.2 provides a series of tables that summarize the OMAs that are performed in each fire area; however these tables appear to indicate different total estimated time durations from what were provided in Section II.C.1. Specifically, it is not clear whether the 30-minute diagnosis time is included in the total estimated time or whether operators proceed to perform other activities once their initial tasks have been completed.

For example, a fire in Fire Area 57 (page 45 of the Attachment) appears to require a single operator to perform multiple tasks as part of a sequence of tasks but does not describe whether the individual operators will proceed to the next task once the first task is completed. For instance, it is not clear whether Operator 1 will continue to their second task after the assumed 12-minute estimated time. It is also not clear whether the estimated and/or allowable times are additive. Operator 1 is responsible for a 12-minute task, a 5-minute task and a 110-minute task but the allowable time is noted as being 150 minutes. This would result in a safety margin of 23 minutes or a 7-minute deficiency if a 30-minute diagnosis time is needed.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 18 of 22 Docket Nos. 50-277 and 50-278 RAI-11.1:

Elaborate on what the 30-minute diagnosis time has been assumed to account for and whether it has been included in the total estimated time for all of the non-prompt OMAs in the request. Also indicate whether any diagnosis time has been accounted for in the prompt action estimated times or why diagnosis time is not necessary.

RESPONSE

The 30-minute diagnosis time is addressed in Section 2 and Section 3.a.1 of the exemption request. Other than for prompt actions (those that have completion times of 30 minutes or less), the diagnostic time is assumed to be 30 minutes, which is conservative as previously described. For the non-prompt OMA, the 30-minute diagnosis time is provided for the control room to evaluate plant conditions, prioritize actions, and determine if the fire will require the OMA to be performed. The non-prompt OMA, for the purposes of the timeline are not assumed to start until after the 30-minute diagnosis time is complete. The application of the 30-minute diagnosis time conservatively introduces a delay in performing the first credited action(s). Since the control room staff will be in a continuous monitoring, prioritization, and diagnosis mode, there is no need to apply the 30-minute diagnosis time to any subsequent actions. If plant conditions that require the OMA to be performed are identified prior to the end of the 30-minute diagnosis period, safe shutdown operators will be dispatched by the control room. The use of the 30-minute diagnosis time has been included in the timeline for each of the non-prompt OMAs.

In addition, as noted in Section 2 of the Exemption Request, the timeline is set up to have "Operator 1" perform all the OMAs unless there is an overlap that would require "Operator 2" and "Operator 3" to be assigned an OMA. The specific example of the OMA in Fire Area 57 will be addressed. Operator 1 performs Action Z and AA starting 30 minutes into the event.

The travel and action time for these two activities is 12 minutes. This leaves time to perform a second action to provide alternate power to a battery charger since the travel and action time is only 5 minutes for a total of 17 minutes (with the time allotted between T=30 and T=60). The second action could have been assigned to Operator 2. Operator 2 would perform the action to disable the RHR Pump Trip which is a 16-minute activity, assumed to start at T=60. The action to Align Valves for the Suppression Pool Cooling has a total time of 110 minutes for a single operator. It is assumed that a single operator starting at T=30 could complete this activity by T=150. However, the other two operators will be available to assist following completion of the other activities which will shorten the amount of time needed to perform this activity.

The diagnosis process for "prompt" actions is addressed in the response to RAI-05.1 RAI-12 Identification and Uniqueness of OMAsSection II.C.1 describes Actions A through GG and Section II.C.2 contains tables indicating the fire areas for which the OMAs would be necessary, however, it is not clear which fire areas the OMAs are located in.

RAI-12.1: Provide a description that includes the fire area of origin, fire area containing the OMA, total estimated/calculated performance time and allowable time for each of the OMAs in the request.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 19 of 22 Docket Nos. 50-277 and 50-278

RESPONSE

Action Initiating Fire Area Manual Action Fire Area(s)

Perf.

Time Allowable Time A

Withdrawn from the exemption request See Attachment 3 B

Fire Area 2, Radwaste Building Yard Area, Unit 2 Start-up Building 15 minutes 120 minutes C

Fire Area 2, Radwaste Building FA 39, E12 Switchgear Room FA 37, E22 Switchgear Room FA 33, E13 Switchgear Room, FA 35, E23 Switchgear Room FA 38, E32 Switchgear Room FA 32, E33 Switchgear Room 15 minutes 15 minutes for 5 fuses; 18 minutes for all 6 fuses 25 minutes Only 5 fuses need to be removed within 25 minutes.

D Fire Area 2, Radwaste Building FA 33, E13 Switchgear Room, FA 38 E32 Switchgear Room 18 minutes 12 minutes for Action D plus 6 minutes for the other two actions.

60 minutes E

Withdrawn from the exemption request See Attachment 3 F

Withdrawn from the exemption request See Attachment 3 G

Fire Area 6S, Unit 2 Reactor Building FA 33, E13 Switchgear Room, FA 38, E32 Switchgear Room 14 minutes 11 minutes for Action G and 3 minutes for the other two actions.

60 minutes H

Fire Area 6N, Unit 2 Reactor Building (North side)

FA 25, Cable Spreading Room 7 minutes 25 minutes

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 20 of 22 Docket Nos. 50-277 and 50-278 Action Initiating Fire Area Manual Action Fire Area(s)

Perf.

Time Allowable Time J

Fire Area 13N, Unit 3 Reactor Building FA 34, E43 Switchgear Room 12 minutes 8 minutes for Action J and 4 minutes for the other actions.

60 minutes K

Fire Area 26, Unit 3 MG Set Ventilation Equipment Room FA 34, E43 Switchgear Room 12 minutes 60 minutes L

Withdrawn from the exemption request See Attachment 3 M

Fire Area 30, Unit 3 B/D Battery Room FA 32, E33 Switchgear Room 9 minutes 60 minutes N

Withdrawn from the exemption request See Attachment 3 P

Withdrawn from the exemption request See Attachment 3 Q

Withdrawn from the exemption request See Attachment 3 R

Fire Area 36, E42 Switchgear Room FA 39, E12 Switchgear Room 12 minutes 60 minutes S

Fire Area 37, E22 Switchgear Room FA 39, E12 Switchgear Room 12 minutes 60 minutes T

Fire Area 43, E-4 Emergency Diesel Generator Room FA 36, E42 Switchgear Room 9 minutes 60 minutes U

Fire Area 50, Turbine Building FA 37, E22 Switchgear Room, FA 38, E32 Switchgear Room, FA 36, E42 Switchgear Room, FA 39, E12 Switchgear Room 8 minutes One bus takes 8 minutes; all 4 buses can be done in 26 minutes.

60 minutes

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 21 of 22 Docket Nos. 50-277 and 50-278 Action Initiating Fire Area Manual Action Fire Area(s)

Perf.

Time Allowable Time V

Fire Area 50, Turbine Building FA 33, E13 Switchgear Room, FA 35, E23 Switchgear Room FA 32, E33 Switchgear Room, FA 34, E43 Switchgear Room 8 minutes One bus takes 8 minutes; all 4 buses can be done in 26 minutes.

60 minutes W

Withdrawn from the exemption request See Attachment 3 X

Fire Area 50, Turbine Building FA 39, E12 Switchgear Room, FA 37, E22 Switchgear Room FA 38, E32 Switchgear Room, FA 36, E42 Switchgear Room, FA 33, E13 Switchgear Room, FA 35, E23 Switchgear Room, FA 32, E33 Switchgear Room, FA 34, E43 Switchgear Room 24 minutes 60 minutes Y

Fire Area 50, Turbine Building Yard Area, Unit 2 Start-up Building 15 minutes 120 minutes Z

Withdrawn from the exemption request See Attachment 3 AA Withdrawn from the exemption request See Attachment 3 BB Fire Area 58 Unit 3 MG Set Room FA 34, E43 Switchgear Room 12 minutes 10 minutes for Action BB and 2 minutes for the other action.

60 minutes CC Fire Area 58 Unit 3 MG Set Room FA 39, E12 Switchgear Room, FA 37, E22 Switchgear Room, FA 38, E32 Switchgear Room, FA 36, E42 Switchgear Room, FA 35, E23 Switchgear Room, FA 32, E33 Switchgear Room, FA 34, E43 Switchgear Room 12 minutes 12 minutes to remove 4 fuses; 21 minutes to remove all 7 fuses.

25 minutes Only four fuses need to be removed within 25 minutes.

DD Withdrawn from the exemption request See Attachment 3

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 22 of 22 Docket Nos. 50-277 and 50-278 Action Initiating Fire Area Manual Action Fire Area(s)

Perf.

Time Allowable Time EE Withdrawn from the exemption request See Attachment 3 FF Withdrawn from the exemption request See Attachment 3 GG Withdrawn from the exemption request See Attachment 3 REFERENCES

1. Letter from P. B. Cowan, Exelon Generation Company, LLC, to U.S. Nuclear Regulatory Commission, "Request for Exemption from 10 CFR 50, Appendix R, Section III.G, 'Fire Protection of Safe Shutdown Capability'," dated March 6, 2009.

2. Letter from J. D. Hughey, U.S. Nuclear Regulatory Commission, to C. G. Pardee, Exelon Generation Company, LLC, "Peach Bottom Atomic Power Station, Units 2 and 3 - Request for Additional Information Regarding Request for Exemption from 10 CFR 50, Appendix R, Section III.G, 'Fire Protection of Safe Shutdown Capability' (TAC Nos. ME0855 and ME0856)," dated November 20, 2009.

ATTACHMENT 2 10 CFR 50.12 Exemption Request Peach Bottom Atomic Power Station, Units 2 and 3 Docket Nos. 50-277 and 50-278 Request for Exemption from 10 CFR 50, Appendix R, Section III.G, Fire Protection of Safe Shutdown Capability" Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 1 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas To address the defense-in-depth aspects of the questions a fire hazards analysis was performed for each OMA that remains in the exemption request. The safe shutdown analysis at PBAPS was performed in a manner that did not specifically identify cables from both trains within a fire area. The analysis approach used at Peach Bottom is described in the PBAPS FPP, Section 5.2.2 as restated below:

The individual components that are used for safe shutdown are listed in Table A-3, together with their corresponding fire area locations and safe shutdown system(s). The safe shutdown analysis was performed from a function/system standpoint, as opposed to a safeguard channel standpoint. Functions and support functions were not restricted to the same safeguard channel as the system used to provide reactor inventory.

Therefore, some components are associated with only one shutdown method, while most components are associated with all four shutdown methods. Although these components are associated with all four methods, they are not necessarily required to be available for all cases in which a given shutdown method is relied on, depending on the location of the postulated fire. This flexibility exists because of the redundancies that have been provided at the system and component levels.

Because of the function/system approach that has been used at PBAPS, in some cases it has not been possible to identify the "two redundant trains" for the purposes of discussing the separation between them. Where this has not been possible, a general discussion of the defense-in-depth has been provided. Where it has been possible to specifically identify redundant cable/equipment that both must fail before the associated manual action is required, a more detailed discussion regarding the separation of these items has been provided.

The fire hazards analyses provide information as to the cable routing within the fire area (or specific room for larger fire areas), fire protection features in the area (room), significant combustible materials, ignition sources exposing the cables and a summary of the type of fire anticipated in the area and the effect on the cables.

The information in the fire hazards analyses contained in this attachment address RAI questions RAI-01.1, RAI-02.2, RAI-02.3, RAI-02.4, RAI-03.1, RAI-04.1, RAI-04.2, RAI-04.3, RAI-06.1, and RAI-08.1.

Action B - Transfer of SU-25 Breaker Auxiliary Equipment to Alternate Power Source The SU-25 breaker auxiliaries are fed from two different diesel backed 480V motor control centers (MCCs) with an automatic transfer switch between the two power supplies. Automatic transfer switch 00B080 feeds the SU-25 auxiliaries and it is in turn fed by alternate power supply breaker 00B5312 (via transformer 0AX048) and normal power supply MCC breaker 00B5612 (via transformer 0BX048). Additionally, there is a third source of power (00L207) to the SU-25 auxiliaries via a manual transfer switch (00S306) which is the supply available following the operator manual action. Cables that feed both MCC 00B53 and MCC 00B56 are located in Fire Area 2, Radwaste Building Common Area. Loss of Cable ZA2B1021A will result in the loss of MCC 00B53. Loss of Cables ZD3B1321A or ZD3A1806A will result in the loss of MCC 00B56.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 2 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas The fire hazards analysis will address the relative location of the cables to each other, consider fire protection features, exposing combustibles and potential ignition sources.

The OMA involves operating a manual transfer switch located in the 2 Start-up Switchgear Building. This is a structure located in the yard area and will not see any fire effects from a fire in the Radwaste Building.

Fire Hazards Analysis Cable Locations Cable ZA2B1021A enters Fire Area (FA) 2 in the common overhead space above room 237, elevation 135'. The cable enters the area approximately 9 feet above the floor and immediately goes up approximately five feet into the ceiling and exits the fire area. The cable is routed in conduit for its entire run in FA 2. The total distance this cable is routed in FA 2 is approximately five feet.

Cable ZD3A1806A enters FA 2 in the common overhead space above room 239, elevation 135'.

The cable enters the area approximately nine feet above the floor. The cable is then routed west into room 238 elevation 135' (FA 2) and then north across room 238 and then through a wall penetration into another fire area. The cable is routed in conduit for its entire length through FA 2.

Cable ZD3B1321A enters FA in room 238, elevation 135' within a non-vented junction box. The cable immediately goes up through the ceiling into another fire area. The cable enters and exits the junction box in conduit.

For the purpose of maintaining the function of power to the SU-25 auxiliaries, cable ZA2B1021A needs to be separated from cables ZD3A1806A and ZD3A1321A.

The conduits containing cables ZA2B1021A and ZD3A1806A are located in a common overhead area and are physically approximately 30 feet apart. While the rooms below the common space have walls, these walls do not extend into the common overhead area. There are no intervening combustibles that run between these two conduits. There are two vertical cable trays that are routed adjacent to the conduit containing ZA2B1021A. These two trays do not create an exposure hazard to ZD3A1806A since they are located approximately 30 feet from the conduit containing ZD3A1806A. There are no horizontal trays routed between or near these two conduits. The overhead space contains ventilation ducts and conduits.

The conduit containing cable ZA2B1021A and the conduit and junction box containing cable ZD3A1321A are separated by approximately 60 feet. There are no intervening combustibles including cable trays that extend between these two locations.

The cables and components associated with the manual transfer switch (00S306) are not located within FA 2.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 3 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas Fire Protection Systems As previously noted, FA 2 is a large fire area containing a number of rooms on several elevations. The three cables associated with this particular operator manual action are located in three adjacent rooms on elevation 135'. There are no fire suppression systems located in these three rooms. Ionization smoke detectors are located in the overhead area (above the suspended ceilings) in rooms 237 and 239. Ionization smoke detection is also provided in room 238. The detection system in these rooms is not code compliant in terms of overall spacing in the fire area. However, there is a smoke detector within 5 feet of cable ZA2B1021A. There is a smoke detector within 15 feet of both cables ZD3A1806A and ZD3A1321A. These ionization detectors will provide notification of a fire condition to the control room while the fire is still in an incipient stage. The smoke detection system is addressed by the PBAPS Technical Requirements Manual (TRM) (which is part of the UFSAR). The TRM specifies a testing frequency and compensatory measures should the system become inoperable. The Radwaste Control Room is located directly adjacent to these three rooms. The Radwaste Control Room is normally occupied by an equipment operator. Any fire would be quickly identified by the operator in the area. The equipment operators are trained fire brigade members. There are portable fire extinguishers and manual hose stations for manual fire fighting located throughout the area.

Room 237 has a floor area of approximately 165 sq. ft with a suspended ceiling height of eight feet. Room 239 has a floor area of approximately 450 sq. ft with a suspended ceiling height of eight feet.

Exposing combustibles The combustible loading in these three rooms is considered to be low, (an equivalent fire severity of 45 minutes or less). Other than a limited number of cable trays, which contain fire retardant cables, there are no combustibles in the overhead that expose the conduits containing these cables. The floor based combustibles include health physics cleaning supplies, such as mops, vacuums and other Class A combustibles. There are several steel carts containing new resins in paper or plastic bags. The total weight of the plastic bags is estimated to be less than 5 pounds. Empty resin bags are immediately removed. None of the floor based combustible materials will create a sustained fire capable of spreading beyond a single target.

Ignition sources There are no high energy ignition sources located in these rooms (i.e., no switchgear, MCCs or transformers). There are no large motors located in the vicinity of these cables. This is not a shop area so hot work activities are infrequent and administrative controls (e.g., hot work permits, fire watch, supervisory controls) are in place if hot work activities do take place.

Summary The separation between the cables is a minimum of 30 feet. There are no combustibles that run between the cables. There is smoke detection that annunciates in the control room within 15 feet of each of the cables. The cables are routed in rigid conduit as they pass through FA 2.

The overall quantity of combustibles in the area is low and there are no ignition hazards in the area. The likelihood of a fire propagating between the two cables sets prior to detection and

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 4 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas extinguishment is very low. Therefore, the need to actually perform a manual action (operate manual transfer switch 00S306) in the event of a fire is also low.

If this manual action must be performed, the action is performed in a separate building that remains unaffected by the fire. There is ample time to perform this action (15 minutes travel and performance time) for a 120-minute action. The need to perform this action in 120 minutes is based on extremely cold exterior temperatures (zero degrees), and the available time climbs as the temperature warms up. Note 1 in Section 2 of the exemption request provides specific information.

Action C, X, and CC - Defeat of 4kV Bus 2SU Feeder Breakers Degraded Voltage Trip Relays Actions C, X and CC involve removing the degraded voltage trip relays for the 4kV Bus 2 SU feeder breakers. This action may be necessary when 2SU is the only offsite power source available and a loss of power to the 2SU transformer tap changer has occurred and the tap changer is not in the correct position. The 2 SU transformer tap changer is powered by balance of plant (BOP) power. BOP power was not modeled as part of the safe shutdown analysis. Any cable or component not modeled in the analysis is assumed lost, regardless of its location.

There are BOP cables routed in Fire Areas 2, 50 and 58, but the routing of the cables are not part of the analysis. Therefore, the loss of BOP was assumed for a fire in these three fire areas.

Further, it was assumed that the transformer tap changer was not in the correct position. When the tap changer is not in the correct position, the voltage could vary resulting in 4kV trip relays actuating. The action to ensure that the 4kV busses remain available is to pull the fuse blocks for the degraded voltage trip relays. A more detailed description of the 2SU feed to the 4kV is provided in the Exemption Request Section C.1, Note 1.

This is the Note 1 from Section 2 of the Attachment modified to specifically address these three actions.

Offsite power is provided to each of the 4kV Class 1E switchgear by two of three redundant sources (2SU, 3SU and 343SU). Control cables for the sources have been separated by rerouting selected cables, such that one of the redundant sources remains free of fire damage for fires in most plant areas. In particular, cables associated with the 2SU source have been relocated out of the Turbine Building (Fire Area 50), and portions of the Radwaste Building (Fire Areas 2 and 58). When the 2SU source is credited, manual actions are procedurally directed by the T-300 Fire Guides to address the potential for a slight voltage degradation.

The 2SU source is provided with an automatic load tap changer, step-down transformer with forced-air and forced-oil cooling, and SF6 gas breaker with gas compressor and heaters. Some of this auxiliary equipment is not powered from a Class 1E power source (i.e., BOP source) and is, therefore, assumed to be lost. This is a limitation in the design, in that even though the 2SU source remains free of fire damage, manual actions will still be required to maintain the availability of the source. Manual actions address the loss of SF6 gas breaker heater and compressor by re-powering the heater and compressor from an available offsite source, via switch 00S306 (Actions B and Y). Without heaters available, the SF6 gas in the breaker is

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 5 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas assumed to slowly cool and liquefy, with the breaker eventually tripping automatically on low gas pressure. This cooldown rate depends on outside temperatures and is estimated to take two hours at 0o F, three hours at 10o F, and indefinitely at or above 45o F. For analysis purposes, 120 minutes is used as the time limit to operate switch 00S306 to restore power to the SF6 gas compressor and heaters. If the action is performed within 120 minutes, then no inadvertent trip of the SU-25 breaker is expected to occur. An indicating light is provided in the 2 Start-up Switchgear Building to notify the operator that the action is required.

No manual actions are required for the loss of forced-air/forced-oil cooling for the step-down transformer, due to the relatively small shutdown loads compared to the normal running loads.

An analysis has been performed for the loss of power to the automatic load tap changer, which has determined that the voltage to the 4kV class 1E switchgear remains acceptable (98% of rated voltage or greater) given the worst case shutdown loads; however, manual actions may be required to pull fuses to disable the 98% non-LOCA undervoltage relays at individual 4kV switchgear that are credited in each fire area. Using reasonable assumptions, the analysis shows that the 98% undervoltage relays will not actuate when at their nominal setting; however, using worse-case assumptions including assuming worse -case shutdown loads are applied, setting tolerances and allowable instrument drift in the worse-case direction, could result in an individual Class 1E switchgear 98% undervoltage relay being susceptible to tripping. Because the potential for a switchgear to trip is based on a worst case shutdown load, instrument setting tolerances and instrument drift, it is unlikely that any 98% undervoltage relay would actuate; however, actions are conservatively shown to be required for all credited 4kV switchgear in each scenario that credits the 2SU as the only available offsite power source.

Since the BOP cables were not modeled as part of the FSSD analysis, a spatial separation review and fire hazards analysis of the cable locations cannot be performed.

The applicable T-300 Fire Guides provide guidance as to when these actions will be needed.

Each of the applicable T-300 Fire Guides give the following direction:

If 2SU is the only off-site power source available, and a loss of power to the 2SU Transformer Tap Change has occurred, then perform the manual action to remove the fuses.

A NOTE is provided in the Fire Guide with this step providing guidance on how to determine if the 2SU transformer tap change has lost power using indications within the control room.

Therefore, the control room will know immediately if this action is required.

The 2SU transformer and associated auxiliaries are located in the Yard area and would not be exposed by a fire in FA 2, FA 50 or FA 58. The physical actions, removal of fuses in the 4kV switchgear rooms are in separate fire areas, with separate ventilation systems from FA 2, FA 50 and FA 58.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 6 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas Summary The potential need to perform this action is low since two of three other off-site sources need to be unavailable. Power to the 2SU transformer tap changer must be lost and the tap changer must be in the wrong position. Even then, only the worst-case assumptions cause the degraded voltage relays to trip. If the degraded voltage relays trip this condition is recoverable and power can be restored. Therefore, while defense-in-depth through cable separation cannot be demonstrated, the likelihood that the actions would be necessary is low.

Action D - Transfer of Battery Charger 2AD003 to Alternate Power Source A fire in Fire Area 2 has the potential to damage cable ZA2B1014A. The loss of this cable will result in a loss of the normal power supply to the 2AD003 battery charger. The battery charger is needed to maintain long term DC power through the station batteries. The amount of time the batteries can operate prior to initiation of recharging is 60 minutes, which is a conservative estimate. Battery charger 2AD003 can also be fed from another power source. The alternate power source is routed in separate fire areas so a single fire cannot damage both the normal and alternate power feed. A manual action is required to transfer the alternate power supply to the battery charger. This action is simply closing a breaker located in the E13 4kV Switchgear Room (FA 33) and then operating a manual transfer switch located in the E32 4kV Switchgear room (FA 38) both of which are separate fire areas from FA 2. This battery charger has a normal feed, with the alternate source from the other unit. Therefore, an automatic transfer switch cannot be used. Since the normal feed and the alternate power supplies are routed in separate fire areas one will always be available. The fire hazards analysis below will address the cables routed in Fire Area 2 that are associated with the normal power feed to the battery charger. The fire hazards analysis will address the cables location, consider fire protection features, exposing combustibles and potential ignition sources. Since the loss of this cable will result in the loss of the normal feed to the battery charger, the FHA will only address the fire hazards exposing this cable.

Battery Charger 2AD003 is located in FA 38.

Fire Hazards Analysis Cable Locations Cable ZA2B1014A enters FA 2 in the common overhead space above room 237, elevation 135' through the east wall in conduit approximately nine feet above the floor. The conduit terminates directly into a ventless junction box located on the wall. The cable then exits the junction box in conduit directly up and out of the room through the ceiling into a different fire area. The conduit travels approximately five feet up from the junction box to the ceiling.

Room 237 has a floor area of 165 sq ft and a height under the suspended ceiling of eight feet.

These cables enter the area above the suspended ceiling. The space between the suspended ceiling and the structural ceiling is approximately six feet.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 7 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas FA 2 is the Radwaste Building general area. The manual actions are performed in switchgear rooms in the turbine building.

Fire Protection Systems FA 2 is a large fire area containing a number of rooms on several elevations. The cable associated with this particular operator manual action is located above room 237 on elevation 135'. There is no fire suppression system located in this room. There are Ionization smoke detectors located in the overhead area (above the suspended ceiling). While the location and spacing of the detectors does not meet the spacing in NFPA 72 for the area as a whole, there is a smoke detector on the structural ceiling approximately five feet from the location of these conduits. This detector will rapidly identify a fire that could expose the conduits. The smoke detection system is addressed by the PBAPS Technical Requirements Manual (TRM) (which is part of the UFSAR). The TRM specifies a testing frequency and compensatory measures should the system become inoperable.. The Radwaste Control Room is located directly adjacent to this room. The Radwaste Control Room is normally occupied by an equipment operator. Any fire would be quickly identified by the operator in the area. The equipment operators are trained fire brigade members. There are portable fire extinguishers and manual hose stations for manual fire fighting located throughout the area.

Exposing Combustibles The combustible loading in this room is considered to be low, (an equivalent fire severity of 45 minutes or less). There is a vertical cable tray, containing cables with fire retardant cable insulation located near the conduits: however, no other combustible materials are located above the suspended ceiling. In the room below the suspended ceiling the floor based combustibles include health physics cleaning supplies, such as mops, vacuums and other Class A combustibles. These items do not directly expose the conduits.

Ignition Sources There are no high energy ignition sources (i.e., no switchgear, MCCs or transformers) located in or near room 237 either above or below the suspended ceiling. This is not a shop area so hot work activities are infrequent and administrative controls (e.g., hot work permits, fire watch, supervisory controls) are in place if hot work activities do take place. There are no significant ignition sources in this room.

Summary The normal power supply and the alternate power supply for the 2AD003 battery charger are routed in separate fire areas so one source will be available. A manual action is required to tie in the alternate power supply using a manual transfer switch, also located in a different fire area.

This fire hazards analysis considered the one cable associated with the normal power supply to the 2AD003 battery charger routed in FA 2. There is reasonable assurance that this cable would not be damaged in the event of a fire in FA 2 room 237. The technical basis that supports this conclusion can be summarized as follows:

The conduit is located above the suspended ceiling; the only exposing combustible is a tray with fire retardant cables.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 8 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas There is a smoke detector located within 5 feet of the location of the conduit that contains cable ZA2B1014A.

There are no ignition sources in the area of the conduit.

The length of cable ZA2B1014A in FA 2 is approximately six feet including the section in the junction box and conduit.

The impact of the fire on the ability to perform this action is low. FA 2 has a separate ventilation system from the switchgear rooms FA 33 and FA 38. There are 60 minutes to perform this action which only takes 18 minutes to perform. The batteries primarily provide DC control power for breaker manipulation. Since the breakers will be in the correct position at the end of the first hour for shutdown conditions, a delay in performing this task will not impact safe shutdown.

Action G - Transfer of Battery Charger 2AD003 to Alternate Power Source A fire in Fire Area 6S has the potential to damage cables ZA2B1014A, ZA2A1505A and ZA2B1021A. The loss of these cables will result in a loss of the normal power supply to the 2AD003 battery charger. The battery charger is needed to maintain long term DC power through the station batteries. The amount of time the batteries can operate prior to initiation of recharging is 60 minutes, which is a conservative estimate. Battery charger 2AD003 can also be fed from another power source. The alternate power source is routed in separate fire areas so a single fire cannot damage both the normal and alternate power feed. A manual action is required to transfer the alternate power supply to the battery charger. This action is simply closing a breaker located in the E13 4kV Switchgear Room (FA 33) and then operating a manual transfer switch located in the E32 4kV Switchgear room (FA 38) both of which are separate fire areas from FA 6S. This battery charger has a normal feed, with the alternate source from the other unit. Therefore, an automatic transfer switch cannot be used. Since the normal feed and the alternate power supplies are routed in separate fire areas one will always be available. The fire hazards analysis below will address the cables routed in Fire Area 6S that are associated with the normal power feed to the battery charger, including cable location, fire protection features, exposing combustibles and potential ignition sources. Since the loss of any of these three cables will result in the loss of the normal feed to the battery charger, the FHA will only address the fire hazards exposing these cables.

Battery Charger 2AD003 is located in FA 38.

Fire Hazards Analysis Cable Locations Cable ZA2B1014A enters FA 6S through the north wall of the Unit 2 Reactor Building on elevation 165' into room 403. The cable is routed in conduit which travels south through the room to a ventless junction box where the cable then enters another conduit. This cable continues south in conduit until it enters a 480 load center.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 9 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas Cable ZA2A1505A enters FA 6S through the north wall of the Unit 2 Reactor Building on elevation 165' into room 403. The cable is routed in conduit which travels south through the room to a 480V load center.

Cable ZA2B1021A enters FA 6S through the north wall of the Unit 2 Reactor Building on elevation 165' into room 403. The cable is routed in conduit which travels south through the room to a ventless junction box where the cable then enters another conduit. This cable continues south in conduit until it enters a 480V load center. This cable and the two conduits are routed together with the conduits that contain cable ZA2B1014A.

Each of the cables is routed approximately 100 feet through room 403. Room 403 is the general area of the Unit 2 Reactor Building 165' elevation with a floor area of approximately 6848 sq. ft and a height of 29 feet.

FA 6S is the Reactor Building general area. The manual actions are performed in switchgear rooms located in the turbine building. There will be no fire effects impacting the performance of the OMAs.

Fire Protection Systems FA 6S is a large fire area comprised of a number of rooms on several elevations of the Unit 2 Reactor Building. The cables associated with this particular operator manual action are located in a single room on elevation 165'. There will be no fire effects from other elevations within this fire area. There are no fire suppression systems located in this room. There are ionization smoke detectors located in the overhead area but these smoke detectors do not have code compliant spacing due to ceiling height and beam pockets. However, there are three smoke detectors located above the general routing of these conduits. The smoke detectors will rapidly identify a fire of a sufficient magnitude to threaten cable within a large diameter conduit. The smoke detection system is addressed by the PBAPS Technical Requirements Manual (TRM)

(which is part of the UFSAR). The TRM specifies a testing frequency and compensatory measures should the system become inoperable. There are portable fire extinguishers and manual hose stations for manual fire fighting located throughout the area.

Exposing Combustibles The combustible loading in this room is considered to be low (an equivalent fire severity of 45 minutes or less). There are a number of cable trays that cross both above and below the conduits containing these cables. The cables within the trays have fire retardant insulation.

There are no floor based combustibles in this area capable of exposing these conduits to damaging conditions. In fact, the conduits are routed primarily through a transient combustible free zone, which administratively controls combustible materials in this area and requires a permit and review prior to the placement of combustibles in this area.

Ignition Sources There are three 480V load centers in this room and these cables are routed to one of the load centers. As a result, each cable is routed over a 480V load center and in two cases the conduit passes over two load centers prior to entering the third load center. The conduits are located

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 10 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas above the two adjacent load centers. The load centers consist of a 4kv to 480v sealed gas-cooled stepdown transformer, and a 480v switchgear. Recent plant experience with faults and malfunctions in similar BOP load centers has been that even when energetic failures have occurred, their damage has been contained within the breaker cubicle, with some heat and smoke damage to immediately adjacent cubicles. Therefore, it is not likely that the subject cables, routed above the load centers would be affected by a fault within the load centers. This is not a shop area so hot work is infrequent in this area and is strictly controlled via a permitting policy.

Summary The normal power supply and the alternate power supply for the 2AD003 battery charger are routed in separate fire areas so one source will be available in the event of a fire in FA 6S. A manual action is required to tie in the alternate power supply using a manual transfer switch, also located in a different fire area. This fire hazards analysis considered the three cables associated with the normal power supply to the 2AD003 battery charger. Certain features, such as fire retardant cables in exposing trays, controls on floor based combustible materials, and smoke detection in the vicinity of the conduits would minimize the potential for a fire exposing the conduits. Although the conduits are routed above two 480v load centers, based on plant experience with faults in similar load centers, it is unlikely that the cables above them would be damaged if an energetic fault occurred. Therefore, the likelihood of this action being necessary is low. There are 60 minutes to perform this OMA and this is the only action that must be performed within the first 60 minutes. The action is performed in a separate fire area that would not see fire effects from a fire in FA 6S. The impact of the fire on the ability to perform this action is low. There are 60 minutes to perform this action which only takes 14 minutes to perform. The batteries primarily provide DC control power for breaker manipulation. Since the breakers will be in the correct position at the end of the first hour for shutdown conditions, a delay in performing this task will not impact safe shutdown. This is the only action for a fire in FA 6S that is performed within the first 60 minutes.

Action H - Bypass of Reactor Low Pressure Permissive for Opening MO-2-025A A fire in Fire Area (FA) 6N has the potential to damage cable ZA2Q1280B. This cable is associated with the pressure permissive circuit needed to open valve MO-2-10-025A. This valve needs to open to permit injection of LPCI ("A" train RHR) following depressurization. The FSSD method for this fire area is Method C, ADS/LPCI. In the event that cable ZA2Q1280B is damaged, a simple manual action, inserting a plug-in test switch into Panel 20C032 in the Cable Spreading Room, is required. FA 6N contains a number of cables associated with the "B" train of RHR. Any number of "B" RHR train cables could be damaged as a result of a fire in FA 6N.

As a result, the "B" RHR was considered to be unavailable for a fire in FA 6N. The fire hazards analysis will address the relative location of the cables to each other, consider fire protection features, exposing combustibles and potential ignition sources.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 11 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas Fire Hazards Analysis Cable Locations Cable ZA2Q1280B enters FA 6N along the east wall near the steam tunnel in room 205 on elevation 135'. The cable is routed to the west in conduit for its entire length in room 205.

Cable ZA2Q1280B remains in the same conduit and enters room 204 (North Isolation Valve Room) also part of FA 6N. The cable and conduit terminate at valve located in room 204.

Any one of a number of cables associated with the "B" RHR train is located in both rooms 204 and 205. Four locations were identified where cable ZA2Q1280B and train "B" RHR cables are in close proximity to each other (within two feet or less). There may be other cases, but these four were considered to be the most limiting. In three cases, the conduit containing cable ZA2Q1280B is routed within two feet or less of a cable tray containing "B" RHR cables. The tray is located below the conduit in two cases (the tray crosses below the conduit) and adjacent in one case. The cable tray exposure is located in room 205. In room 204, cable ZA2Q1280B terminates at MO-2-10-017. A "B" train cable also terminates at this valve, so both trains are within inches at this location.

FA 6N is the Unit 2 Reactor Building 135' elevation, north side. This location is in a separate building from the Cable Spreading Room, FA 25 which is the location of the manual action and the Turbine Building (travel path). This fire will have no impact on the operator performing this function.

Fire Protection Systems As previously noted, FA 6N consists of the general area of the Unit 2 Reactor Building North side and the North Isolation Valve room. FA 6N has smoke detection, but the spacing is not in accordance with NFPA 72 due to deep beam pockets at the ceiling of this area. There is a smoke detector within the vicinity (approximately 25 feet) of each of the cases where cable ZA2Q1280B and a "B" RHR cable intersect. There is no fire suppression system in the general area of FA 6N. There is an automatic water curtain on the west side of the Unit 2 Reactor Building that separates FA 6N from FA 6S. There is an approved exemption (NRC Letter dated March 13, 1985) for the use of this water curtain to provide separation between FA 6N and FA 6S. Cable ZA2Q1280B does not run close to the water curtain. In addition, the OMA is not performed in FA 6S, so the water curtain is not a factor in this exemption request. There are portable fire extinguishers and manual hose stations for manual fire fighting located throughout the area.

Exposing Combustibles The combustible loading in FA 6N is considered to be low, (an equivalent fire severity of 45 minutes or less). The primary combustible material in the area is cable insulation from cables in trays. The cables are qualified to IEEE 383 (or equivalent). There are no other significant floor based combustibles in this area. The trash cans have flame tamer lids which provide self-extinguishing capability to the trash cans. FA 6N contains the primary access to the drywell.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 12 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas Ignition Sources There are no high energy ignition sources (i.e., no switchgear, MCCs or transformers) located in the vicinity of cable ZA2Q1280B and there are no high energy ignition sources where cable ZA2Q1280B and a "B" RHR train cable cross. There are no large motors located in the vicinity of these cables. While there are 480V load centers located on this elevation of the Reactor Building, none are located near these cables. This is not a shop area so hot work activities are infrequent and administrative controls (e.g., hot work permits, fire watch, supervisory controls) are in place if hot work activities do take place.

Summary There is limited separation between cable ZA2Q1280B (associated with "A" RHR) and cables associated with "B" RHR. There is smoke detection that annunciates in the control room within approximately 25 feet of where the cables cross. Cable ZA2Q1280B is routed in conduit. The cables associated with "B" RHR are located in both tray and conduit. The overall quantity of combustibles in the area is low and there are no ignition hazards that directly expose cable ZA2Q1280B in the area. Since the cables for both "A" and "B" RHR trains cross over each other (within two feet) it is possible that a single fire could damage both the "A" train RHR cable and "B" RHR cables. However, the manual action for this condition is simply installing a test plug in a control panel located in a separate building that will be completely unaffected by a fire in FA 6N. The control panel that needs the test plug is located in the Cable Spreading Room, which is directly below the Control Room. FA 6S and the Cable Spreading Room are in different buildings with different ventilation systems so there will be no fire effects encountered while performing this OMA.

Action J - Transfer of Battery Charger 3DD003 to Alternate Power Source A fire in Fire Area (FA) 13N has the potential to damage cables ZD3B1313A, ZD3A1806A and ZD3B3983A. The loss of any of these cables will result in a loss of the normal power supply to the 3DD003 battery charger. The battery charger is needed to maintain long term DC power through the station batteries. The amount of time the batteries can operate prior to initiation of recharging is 60 minutes, which is a conservative estimate. Battery charger 3DD003 can also be fed from another power source. The alternate power source is routed in separate fire areas so a single fire cannot damage both the normal and alternate power feed. The manual action is required to transfer the alternate power supply to the battery charger. This action is to first close a breaker and then simply operate a manual transfer switch; both are located in the E43 4kV Switchgear room which is a separate fire area (FA 34). This battery charger has a single normal feed, with the alternate source from the other unit. Therefore, an automatic transfer switch cannot be used. Since the normal feed and the alternate power supplies are routed in separate fire areas, one power supply will always be available. The fire hazards analysis below will address the three cables routed in Fire Area 13N that are associated with the normal power feed to the battery charger. The fire hazards analysis will address the cable locations, consider fire protection features, exposing combustibles and potential ignition sources. Since the loss of any of these cables will result in the loss of the normal feed to the battery charger, the FHA will not address the separation of these three cables from each other.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 13 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas Battery Charger 3DD003 is located in FA 34, the E43 Switchgear Room.

Fire Hazards Analysis Cable Locations Cable ZD3B1313A originates in FA 13N, Unit 3 Reactor Building, elevation 165' at a 480V load center. The cable leaves the load center in conduit and heads generally north. When the conduit reaches the north wall, it turns west and runs parallel to the north wall. When the conduit reaches the northwest corner of this elevation, the conduit is routed through the floor to the 135' elevation of the Unit 3 Reactor Building, which is still part of FA 13N. The conduit and cable terminate in a MCC panel located in the northwest corner of the 135' elevation.

Cable ZD3A1806A enters FA 13N, Unit 3 Reactor Building, elevation 165' through the south wall in conduit. The conduit is routed in the overhead in a general northeast direction. The conduit and cable terminate in a 480V load center located on elevation 165 in FA 13N.

Cable ZD3B3983A originates in FA 13N at a MCC panel located in the northwest corner of elevation 135'. The cable enters a horizontal tray that is routed east along the north wall of elevation 135'. The cable then enters a vertical tray that runs up the north wall and goes through the floor of elevation 165' (still within FA 13N). The cable transfers to a horizontal tray that runs south across elevation 165'. When the cable reaches the south side of elevation 165' it transfers to another horizontal tray routed west. When the cable nears the west side of the room, the cable enters a tray that runs horizontally to the south wall, where the cable is routed through the wall into a separate fire area.

FA 13N includes a large part of the Unit 3 Reactor Building; 135' elevation north side, all of 165' elevation, all of 195' elevation and all of 234' elevation. The manual action is performed in the E43 Switchgear room which is a separate fire area (FA 34) located in the turbine building. A fire in FA 13N will have no impact on the operator performing the actions in the switchgear room.

Battery charger 3DD003 is located in FA 34.

Fire Protection Systems FA-13N includes several elevations of the Unit 3 Reactor Building. The 135' elevation of the Unit 3 Reactor Building within FA 13N has a floor area of 4033 sq. ft and a height of approximately 29 feet. The 165' elevation has a floor area of 6848 sq. ft and a height of approximately 29 feet. Both elevations have smoke detection systems that alarm in the control room. Due to the room height and steel beams at the ceiling, the space of the smoke detectors on both elevations does not meet the spacing listed in NFPA 72. However, for a fire of the magnitude necessary to damage cables the smoke detection in the area will provide notification of the fire condition. The smoke detection system is addressed by the PBAPS Technical Requirements Manual (TRM) (which is part of the UFSAR). The TRM specifies a testing frequency and compensatory measures should the system become inoperable. The only fire suppression system in this fire area is not located near any of the cable routings and has no

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 14 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas impact on the exposure to these cables. There are portable fire extinguishers and manual hose stations located throughout the fire area on all elevations.

Exposing Combustibles The combustible loading in FA 13N is considered to be low, (an equivalent fire severity of less than 45 minutes). The primary combustible material in both elevations within FA 13N is fire retardant cable insulation. Other minor amounts of Class A combustible materials including step-off pads can be found in this area. The three cables whether in tray or in conduit, are routed such that they cross over a number of cable trays.

Ignition Sources The three cables addressed here are routed such that they terminate at either a 480V load center or an MCC cabinet or both. These devices can create a high energy fault that could create sufficient heat to damage cable with the heat plume. Each of the cables is routed over a load center or MCC at some point in their routing.

Summary The normal power supply and the alternate power supply for the 3DD003 battery charger are routed in separate fire areas so one source will be available in the event of a fire in FA 13N. A manual action is required to tie in the alternate power supply which involves closing a breaker and operating a manual transfer switch, also located in a different fire area. This fire hazards analysis considered the three cables associated with the normal power supply to the 3DD003 battery charger. There is a potential that any one of these three cables could be damaged as a result of a fault or failure within its associated 480V load center or MCC.

The impact of the fire on the ability to perform this action is low. FA 13N is in a separate building with a separate ventilation system from the switchgear room FA 34. There are 60 minutes to perform this action which only takes 12 minutes to perform. This is only OMA for FA 13N that is performed within the first 60 minutes. The batteries primarily provide DC control power for breaker manipulation. Since the breakers will be in the correct position at the end of the first hour for shutdown conditions, a delay in performing this task will not impact safe shutdown.

Action K - Transfer of Battery Charger 3DD003 to Alternate Power Source A fire in Fire Area 26 has the potential to damage cables ZD3A1806A and ZD3B3983A. The loss of either of these cables will result in a loss of the normal power supply to the 3DD003 battery charger. The battery charger is needed to maintain long term DC power through the station batteries. The amount of time the batteries can operate prior to initiation of recharging is 60 minutes, which is a conservative estimate. Battery charger 3DD003 can also be fed from another power source. The alternate power source is routed in separate fire areas so a single fire cannot damage both the normal and alternate power feed. The manual action is required to transfer the alternate power supply to the battery charger. This action is to first close a breaker and then simply operating a manual transfer switch; both are located in the E43 4kV Switchgear room which is a separate fire area (FA 34). This battery charger has a single normal feed, with

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 15 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas the alternate source from the other unit. Therefore, an automatic transfer switch cannot be used. Since the normal feed and the alternate power supplies are routed in separate fire areas, one power supply will always be available. The fire hazards analysis below will address the two cables routed in Fire Area 26 that are associated with the normal power feed to the battery charger. The fire hazards analysis will address the cable locations, consider fire protection features, exposing combustibles and potential ignition sources. Since the loss of either cable will result in the loss of the normal feed to the battery charger, the FHA will not address the separation of these two cables from each other.

Battery Charger 3DD003 is located in FA 34.

Fire Hazards Analysis Cable Locations Cable ZD3A1806A enters FA 26 through the floor (from a separate fire area) in conduit along the north wall of FA 26 (room 382). The conduit enters a ventless junction box mounted on the wall. The cable exits the junction box in conduit and penetrates the north wall into a separate fire area. The total length the cable is in the area is approximately 10 feet.

Cable ZD3B3983A enters FA 26 through the floor (from a separate fire area) in a cable tray.

The tray is routed from the floor along the north wall and then the cable is routed through a penetration along the north wall into a separate fire area. The total length the cable is in the area is approximately 15 feet.

FA 26 is the Unit 3 MG set ventilation equipment room located on the 165' elevation of the Radwaste Building. The manual action is performed in the E43 Switchgear room which is a separate fire area (FA 34) located in the turbine building. A fire in FA 26 will have no impact on the operator performing the actions in the switchgear room.

Fire Protection Systems FA 26 is the Unit 3 MG set ventilation equipment room (room 382). This room has a floor area of 2100 sq. ft and a height of approximately 25 feet. This room is divided into sections by a steel plenum. The portion of the room along the north wall, where the cables are located does not contain any ventilation equipment and has an area of approximately 360 sq. ft (6 feet by 60 feet). There are two ionization smoke detectors located in the portion of the room where the cables are located. The overall detector placement for the entire fire area does not meet the layout and spacing of NFPA 72; however, the two smoke detectors are located in the immediate vicinity of the cables and would provide an alarm of a fire condition. The smoke detection system is addressed by the PBAPS Technical Requirements Manual (TRM) (which is part of the UFSAR). The TRM specifies a testing frequency and compensatory measures should the system become inoperable. There is no suppression system provided for FA 26. There are portable fire extinguishers and manual hose stations located outside the room.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 16 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas Exposing Combustibles The combustible loading in FA 26 is considered to be low, (an equivalent fire severity of 45 minutes or less). The primary combustible material in the area cable insulation, which is fire retardant. There are no combustibles in this area that could create a high heat release rate fire.

Ignition Sources There are no high energy ignition sources (i.e., no switchgear, MCCs or transformers) located in FA 26. In the portion of the room where the cables are located there are no motors, fans or other electrical components. This is not a shop area so hot work activities are infrequent and administrative controls (e.g., hot work permits, fire watch, supervisory controls) are in place if hot work activities do take place. There are no significant ignition sources in this room.

Summary The normal power supply and the alternate power supply for the 3DD003 battery charger are routed in separate fire areas so one source will be available in the event of a fire in FA 26. A manual action is required to tie in the alternate power supply which involves closing a breaker and operating a manual transfer switch, also located in a different fire area. This fire hazards analysis considered the two cables associated with the normal power supply to the 3DD003 battery charger. There is reasonable assurance that both these cables would not be damaged in the event of a fire in FA 26. The technical basis that supports this conclusion can be summarized as follows:

There are no ignition sources in FA 26 in the vicinity of the cables, There are no combustible materials, other than fire retardant cable insulation exposing the two cables, and Two smoke detectors are provided in the area of the cables.

The impact of the fire on the ability to perform this action is low. FA 26 is in a separate building with a separate ventilation system from the switchgear room FA 34. There are 60 minutes to perform this action which only takes 12 minutes to perform. This is the only OMA for FA 26.

The batteries primarily provide DC control power for breaker manipulation. Since the breakers will be in the correct position at the end of the first hour for shutdown conditions, a delay in performing this task will not impact safe shutdown.

Action M - Transfer of Battery Charger 3AD003 to Alternate Power Source A fire in Fire Area (FA) 30 has the potential to damage cables ZA3B1014A and ZA3A1505A.

The loss of either of these cables will result in a loss of the normal power supply to the 3AD003 battery charger. The battery charger is needed to maintain long term DC power through the station batteries. The amount of time the batteries can operate prior to recharging is 60 minutes, which is a conservative estimate. Battery charger 3AD003 can also be fed from another power source. The alternate power source is routed in separate fire areas so a single fire cannot damage both the normal and alternate power feed. The manual action is required to transfer the alternate power supply to the battery charger. This action is simply operating a manual transfer switch located in the E33 4kV Switchgear room which is a separate fire area.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 17 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas This battery charger has a single normal feed, with the alternate source from the other unit.

Therefore, an automatic transfer switch cannot be used. Since the normal feed and the alternate power supplies are routed in separate fire areas one will always be available. The fire hazards analysis below will address the two cables routed in FA 30 that are associated with the normal power feed to the battery charger. The fire hazards analysis will address the cable location, consider fire protection features, exposing combustibles and potential ignition sources.

Since the loss of either cable will result in the loss of the normal feed to the battery charger, the FHA will not address the separation of these two cables from each other.

Battery Charger 3AD003 is located in FA 32.

Fire Hazards Analysis Cable Locations Cable ZA3B1014A enters FA 30 along the south wall and is routed in conduit. The conduit is routed north approximately four feet, then turns west and is routed approximately 12 feet to exit FA 30 through the west wall. Cable ZA3A1505A enters FA 30 along the south wall (approximately 16 inches from cable ZA3B1014A) and is routed in conduit. The conduit is routed north and then turns west and exits FA 30 through the west wall. Both conduits containing these cables are encapsulated in abandoned Thermo-lag. The abandoned Thermo-lag remains intact for the entire length that both conduits are routed through FA 30. This Thermo-lag was considered to have a three-hour fire resistance rating when installed.

Subsequently, it was determined that the three-hour Thermo-lag material as originally installed at PBAPS had a fire resistance rating closer to one hour. This Thermo-lag was abandoned in place and remains intact for the entire route of each conduit through FA 30. No upgrades or modifications were performed on this section of Thermo-lag, so a fire resistance rating for the abandoned Thermo-lag is not being specified.

FA 30 is the Unit 3 B/D battery room. The manual action is performed in the E33 Switchgear room which is a separate fire area (FA 32). This fire will have no impact on the operator performing this function.

Fire Protection Systems As previously noted, FA 30 is the Unit 3 B/D battery room. This room has a floor area of 525 sq.

ft and a height of 14 feet. There are three smoke detectors located in the room, and the spacing is compliant with NFPA 72 considering ceiling height, beams and air flow. Two of the three smoke detectors are located directly above the encapsulated conduits. The smoke detection system is addressed by the PBAPS Technical Requirements Manual (TRM) (which is part of the UFSAR). The TRM specifies a testing frequency and compensatory measures should the system become inoperable. There is no suppression system provided for FA 30. There are portable fire extinguishers within FA 30 and manual hose stations located outside the room, but nearby.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 18 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas Exposing Combustibles The combustible loading in FA 30 is considered to be low, (an equivalent fire severity of 45 minutes or less). The primary combustible material in the area is the liquid filled plastic battery cases. There are no cables in trays in this fire area. There are no combustibles in this area that could create a high heat release rate fire. The potential for hydrogen buildup due to the battery charging process is mitigated by the ventilation system in the room. The ventilation system is monitored and alarmed and is addressed by the PBAPS TRM.

Ignition Sources There are no high energy ignition sources (i.e., no switchgear, MCCs or transformers) located in FA 30. This is not a shop area so hot work activities are infrequent and administrative controls (e.g., hot work permits, fire watch, supervisory controls) are in place if hot work activities do take place. There are no significant ignition sources in this room.

Summary The normal power supply and the alternate power supply for the 3AD003 battery charger are routed in separate fire areas so one will be available. A manual action is required to tie in the alternate power supply using a manual transfer switch, also located in a different fire area. This fire hazards analysis considered the two cables associated with the normal power supply to the 3AD003 battery charger. There is reasonable assurance that both these cables would not be damaged in the event of a fire in FA 30. The technical basis that supports this conclusion can be summarized as follows:

The conduits containing cables ZA3B1014A and ZA3A1505A are both encapsulated in abandoned Thermo-lag. This Thermo-Lag remains intact on both conduits for their entire length through FA 30.

This Thermo-lag was originally installed with a three-hour fire resistance rating.

Subsequent tests determined that this design and installation was closer to a one-hour fire resistance rating. Since this Thermo-lag was not upgraded a specific rating is not specified. However, it is reasonable to conclude the abandoned Thermo-lag will provide protection to the cables for a duration exceeding the combustible loading in the room.

The primary combustible material in the room is liquid filled plastic battery cases.

There are no cable trays in this room. There are no high voltage components that could create a sustained fault to expose these cables.

This 525 sq. ft room has three smoke detectors, two of which are installed directly above the encapsulated conduits.

The potential for hydrogen release from the battery charging process is mitigated by the ventilation system that is monitored for operation and addressed by the Technical Requirements Manual.

The impact of the fire on the ability to perform this action is low. There are 60 minutes to perform this action which only takes nine minutes to perform. The batteries primarily provide DC control power for breaker manipulation. Since the breakers will be in the correct position at

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 19 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas the end of the first hour for shutdown conditions, a delay in performing this task will not impact safe shutdown.

Action R - Restoration of Power to E12 Bus From E1 Diesel Generator A fire in Fire Area (FA) 36 has the potential to damage cables ZA2A1501E, ZA2A1501F, ZA2A1508E and ZA2A1508F. Loss of these cables could result in the loss of power to the E12 bus from the E1 Emergency Diesel Generator. FA 36 is the E42 4kV Switchgear Room, room 226 located on the 135' elevation of the Turbine Building. The switchgear in this room is primarily associated with the B and D electrical trains, so a fire in this room is assumed to result in the loss of the components associated with the B and D trains. The manual action required in the event of the loss of these cables is to enter the E12 Switchgear room (FA 39) and pull two fuse blocks, open two breakers by depressing the mechanical breaker trip button and taking a main control room breaker control switch to "Close." Since these cables are associated with the "A" train and are located in a room with "B" and "D" train components, any one of a number of B and D train components that become damaged due to a fire will require the use of the "A" train systems. There is little spatial separation between these cables and the B and D train components in the room. The fire hazards analysis will address the location of these cables in the room, consider fire protection features, exposing combustibles and potential ignition sources.

Fire Hazards Analysis Cable Locations Cables ZA2A1501E, ZA2A1501F, ZA2A1508E and ZA2A1508F are routed together in a single conduit for their entire length in FA 36. The conduit enters FA 36 at the ceiling (from the Cable Spreading Room FA 25). The conduit drops approximately five feet from the ceiling and is routed east, where it penetrates the east wall into FA 37. The conduit is routed approximately nine feet above the floor. The cable crosses over two battery chargers, but does not cross above any of the 4kV switchgear cabinets. The conduit is below the top of the 4kV switchgear and approximately 4 feet from the front of the 4kV switchgear cabinets. The conduit is not encapsulated.

FA 36 is the E42 4kV Switchgear Room, 135' elevation, of the Turbine Building. The manual action in the event of a fire in FA 36 is performed in FA 39, the E12 4kV Switchgear Room.

These rooms are located near one another, but they are separate fire areas with separate access doors. There are no doors that communicate directly between these two fire areas. A fire in FA 36 will not impact the ability to perform a manual action in FA 39.

Fire Protection Systems FA 36 is provided with six smoke detectors in a 525 sq. ft room with a height of 14 feet. This provides NFPA 72 code compliant coverage. The room is also provided with a pre-action sprinkler system with sprinkler head locations and spacing provided in accordance with NFPA

13. The pre-action sprinkler system and smoke detection systems are addressed by the PBAPS Technical Requirements Manual (TRM) (which is part of the UFSAR). The TRM

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 20 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas specifies a testing frequency and compensatory measures should the systems become inoperable. There are portable fire extinguishers located within this room and fire hose stations for manual fire fighting are located directly outside of the room.

Exposing Combustibles The combustible loading in FA 36 is considered to be low (an equivalent fire severity of 45 minutes or less). The primary combustible material in the area is cable insulation from cables in trays. The cables are qualified to IEEE 383 (or equivalent). There are no cable trays located directly under conduit containing the four cables. There are no other significant floor based combustibles in this area. There are several sections of Thermo-lag in the room, but this material does not create a credible exposure to the conduit.

Ignition Sources FA 36 contains 4kV switchgear which can create a high energy fault in the event of a failure and must be considered an ignition source. The conduit is not routed over the switchgear. The conduit is routed approximately four feet in front of the 4kV switchgear cabinets and physically lower than the top of the switchgear. The conduit is located outside of what would be anticipated to be the heat plume in the event of a switchgear failure. Since the conduit would not be damaged by the initial switchgear failure, the subsequent actuation of the sprinkler system will provide protection to the conduit and the cable within the conduit.

The conduit containing the four cables of concern are routed over two battery chargers. These chargers change 480 volt AC into 125 volt DC for the batteries. These chargers are not anticipated to provide a sustained fault current like a 4kV switchgear, but heat from a failure could expose the conduit until the actuation of the pre-action sprinkler system.

This is not a shop area so hot work activities are infrequent and administrative controls (e.g., hot work permits, fire watch, supervisory controls) are in place if hot work activities do take place.

Summary FA 36 contains primarily cables and components associated with the B and D electrical trains, so there is limited separation between "A" train cables ZA2A1501E, ZA2A1501F, ZA2A1508E and ZA2A1508F located in a conduit routed through FA 36. While a single fire could damage these cables and adjacent cables and components from the B and D trains, the potential for the cables within the conduit surviving a fire in FA 36 is supported by the following:

FA 36 has full area detection and a full area pre-action sprinkler system, The conduit is not routed directly above the 4kV switchgear and would not be damaged by the initial failure of a 4kV switchgear, The combustible loading in the room is low consisting primarily of fire retardant cable insulation and Thermo-lag, and There are no cable trays routed below the conduit.

This is the only OMA that is required to be performed in the event of a fire in FA 36. The action to pull two fuse blocks, open breakers and energize the bus takes only 12 minutes. There are

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 21 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas 60 minutes to perform this action. Even considering that 30 minutes of the 60 will be taken up by condition diagnosis in the control room, there is still adequate time, with ample margin to perform this OMA. This action supports restoration of AC power to battery chargers for credited safe shutdown batteries. The batteries primarily provide DC control power for breaker manipulation. Since the breakers will be in the correct position at the end of the first hour for shutdown conditions, a delay in performing this task will not impact safe shutdown.

Action S - Restoration of Power to E12 Bus From E1 Diesel Generator A fire in Fire Area (FA) 37 has the potential to damage cables ZA2A1501E, ZA2A1501F, ZA2A1508E and ZA2A1508F. Loss of these cables could result in the loss of power to E12 bus from the E1 Diesel Generator. FA 37 is the E22 4kV Switchgear Room, room 231 located on the 135' elevation of the Turbine Building. The switchgear in this room is primarily associated with the B and D electrical trains, so a fire in this room is assumed to result in the loss of the components associated with the B and D trains. The manual action required in the event of the loss of these cables is to enter the E12 Switchgear room (FA 39) and pull two fuse blocks, open two breakers by depressing the mechanical breaker trip button and taking a main control room breaker control switch to "Close." Since these cables are associated with the "A" train and are located in a room with "B" and "D" train components, any one of a number of B and D train components that become damaged due to a fire will require the use of the "A" train systems.

There is little spatial separation between these cables and the B and D train components in the room. The fire hazards analysis will address the location of these cables in the room, consider fire protection features, exposing combustibles and potential ignition sources.

Fire Hazards Analysis Cable Locations Cables ZA2A1501E, ZA2A1501F, ZA2A1508E and ZA2A1508F are routed together in a single conduit for their entire length in FA 37. The conduit enters FA 37 through the west wall from FA

36. The conduit is routed east approximately 15 feet and then turns south and runs an additional five feet until it penetrates the south wall into FA 39. The conduit is routed approximately 9 feet above the floor. The cable crosses over a bank of 480V motor control centers (MCCs), but does not cross above any of the 4kV switchgear cabinets. The conduit is below the top of the 4kV switchgear and approximately 4 feet from the front of the 4kV switchgear cabinets. The conduit is not encapsulated.

FA 37 is the E22 4kV Switchgear Room, 135' elevation, of the Turbine Building. The manual action in the event of a fire in FA 37 is performed in FA 39, the E12 4kV Switchgear Room.

These rooms are located adjacent to one another, but they are separate fire areas with separate doors. There are no doors that communicate directly between these two fire areas. A fire in FA 37 will not impact the ability to perform a manual action in FA 39.

Fire Protection Systems FA 37 is provided with three smoke detectors in a 525 sq. ft room with a ceiling height of 14 feet. This provides NFPA 72 code compliant coverage. The room is also provided with a pre-

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 22 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas action sprinkler system with sprinkler head locations and spacing provided in accordance with NFPA 13. The pre-action sprinkler system and smoke detection system are addressed by the PBAPS Technical Requirements Manual (TRM) (which is part of the UFSAR). The TRM specifies a testing frequency and compensatory measures should the system become inoperable. There are portable fire extinguishers located within this room and fire hose stations for manual fire fighting are located directly outside of the room.

Exposing Combustibles The combustible loading in FA 37 is considered to be low (an equivalent fire severity of 45 minutes or less). The primary combustible material in the area is cable insulation from cables in trays. The cables are qualified to IEEE 383 (or equivalent). There are no cable trays located directly under conduit containing the four cables. There are no other significant floor based combustibles in this area. There are several sections of Thermo-lag in the room, but this material does not create a credible exposure to the conduit.

Ignition Sources FA 37 contains 4kV switchgear which can create a high energy fault in the event of a failure and must be considered an ignition source. The conduit is not routed over the switchgear. The conduit is routed approximately four feet in front of the 4kV switchgear cabinets and physically lower than the top of the switchgear. The conduit is located outside of what would be anticipated to be the heat plume in the event of a switchgear failure. Since the conduit would not be damaged by the initial switchgear failure, the subsequent actuation of the sprinkler system will provide protection to the conduit and the cable within the conduit.

The conduit containing the four cables of concern crosses a bank of 480V MCCs. These MCCs create an exposure hazard to the conduit. However, the detection and pre-action sprinkler system should be able to provide protection to the conduit in the event an MCC fails.

This is not a shop area so hot work activities are infrequent and administrative controls (e.g., hot work permits, fire watch, supervisory controls) are in place if hot work activities do take place.

Summary FA 37 contains primarily cables and components associated with the B and D trains, so there is limited separation between "A" train cables ZA2A1501E, ZA2A1501F, ZA2A1508E and ZA2A1508F located in a single conduit routed through FA 37. While a single fire could damage these cables and adjacent cables and components from the B and D trains, the potential for the cables within conduit ZA2A198 surviving a fire in FA 37 is supported by the following:

FA 37 has full area detection and a full area pre-action sprinkler system, The conduit is not routed directly above the 4kV switchgear and would not be damaged by the initial failure of a 4kV switchgear, The combustible loading in the room is low consisting primarily of fire retardant cable insulation and Thermo-lag, and There are no cable trays routed below the conduit.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 23 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas This is the only OMA that is required to be performed in the event of a fire in FA 37. The action to pull two fuse blocks, open breakers and energize the bus takes only 12 minutes. There are 60 minutes to perform this action. Even considering that 30 minutes of the 60 will be taken up by condition diagnosis in the control room, there is still adequate time, with ample margin to perform this OMA. This action supports restoration of AC power to battery chargers for credited safe shutdown batteries. The batteries primarily provide DC control power for breaker manipulation. Since the breakers will be in the correct position at the end of the first hour for shutdown conditions, a delay in performing this task will not impact safe shutdown.

Action T - Transfer of Battery Charger 2DD003 to Alternate Power Source A fire in Fire Area (FA) 43 (E4 Emergency Diesel Generator Room) has the potential to damage cables ZD2A1807E or ZD2A1807H. Failure of these cables via a hot short could cause the Unit 2 emergency diesel generator breaker to close into the E42 bus, either out of phase or not running causing a protective trip of the E42 bus. Protective trip of this bus will result in a loss of the normal power supply to the 2DD003 battery charger. The battery charger is needed to maintain long term DC power through the station batteries. The amount of time the batteries can operate prior to recharging is 60 minutes, which is a conservative estimate. Battery charger 2DD003 can also be fed from another power source. The alternate power source is routed in separate fire areas so a single fire cannot damage both the normal and alternate power feed.

The manual action is required to transfer the alternate power supply to the battery charger. This action is simply operating a manual transfer switch located in the E42 4kV Switchgear room which is a separate fire area in a separate building. This battery charger has a single normal feed, with the alternate source from the other unit. Therefore, an automatic transfer switch cannot be used. Since the normal feed and the alternate power supplies are routed in separate fire areas one will always be available. The fire hazards analysis below will address the two cables routed in Fire Area 43 that are associated with the normal power feed to the battery charger. The fire hazards analysis will address the cable location, consider fire protection features, exposing combustibles and potential ignition sources. Since the loss of either cable will result in the loss of the normal feed to the battery charger, the FHA will not address the separation of these two cables from each other.

Battery Charger 2DD003 is located in FA 36.

Fire Hazards Analysis Cable Locations Cable ZD2A1807E is routed in conduit which is embedded in the concrete floor until it enters a junction box on the south wall of FA 43. Cable ZD2A1807E leaves the junction box in conduit which becomes embedded in the floor when it leaves the junction box enroute to diesel control panel 0DC97. Cable ZD2A1807E leaves diesel control panel 0DC97 in conduit which leaves the panel through the floor and is embedded in the floor under the diesel generator to panel 0DC142.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 24 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas Cable ZD2A1807H is routed in conduit from diesel control panel 0DC97 to panel 0DC142. This conduit is embedded in the floor between the two panels.

While the conduits that contain these cables are embedded in the concrete floor, the cables are located in control panels and a junction box.

FA 43 is the E4 Emergency Diesel Generator (EDG) Room. Each of the emergency diesel generators are separated from one another with a three-hour rated fire barrier. The four EDG rooms are located in a separate building that is not attached to any other plant structures and does not create an exposure hazard to any other structures. The manual action for a fire in FA 43 is performed in the E42 Switchgear room FA 36, which is located in the turbine building. A fire in FA 43 will have no impact on performing the manual action in FA 36. This OMA is the only action necessary for a fire in FA 43. The travel and action time for this OMA is nine minutes. This is a 60-minute action, so even with a 30 minute diagnostic time, there is over 100% margin to perform this action.

Fire Protection Systems FA 43 is an EDG room. Each of the EDG rooms has eight heat detectors that alarm in the control room. Each EDG room has a manually actuated CO2 fire suppression system. An exemption to make this CO2 system manual was granted by the NRC in a letter dated June 24, 2005. This CO2 design concentration for the EDG rooms systems are 50% which is well above the NFPA 12 design concentration of 34% for oil hazards. Therefore, upon discharge, the CO2 system will effectively suppress the fire. Fire extinguishers are located in the room and there are fire hydrants and hose houses located outside the diesel building.

Exposing Combustibles The primary combustible materials in the EDG room are diesel fuel and lube oil. Other than the lube and fuel oil, the other combustibles in the room are minor. The fuel oil day tank is located with the fire area, but in a separate room with heavy concrete walls and a three-hour Underwriters Laboratory Listed fire door. However, since these walls and door are within the same fire area, they are not credited as fire barriers per Appendix R. In the event of an EDG failure or a failure of the lube oil or fuel oil pumps an oil fire could occur in the room.

Ignition Sources An operating diesel generator which incurs some type of failure creates a significant ignition source. There are also high voltage electrical components associated with the generator in the room. These ignition sources are only credible when the diesel is in operation. Typically, during routine diesel operations, an equipment operator is stationed in the room to monitor the diesel, and would be available to immediately suppress any small fires that occurred, or to secure the diesel if a significant malfunction occurred.

Summary The normal power supply and the alternate power supply for the 2DD003 battery charger are routed in separate fire areas so one will be available. A manual action is required to tie in the alternate power supply using a manual transfer switch, also located in a different fire area. This

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 25 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas fire hazards analysis considered the two cables associated with the normal power supply to the 2DD003 battery charger. While the conduits that carry these cables are embedded in the floor slab, the cables are also located in control panels in the room. An oil fire (lube oil or fuel oil) in the room has the potential to spread across the floor and expose these control panels and their contents. The CO2 system in the room provides suppression of the system once actuated.

However, since the CO2 system is manually actuated, it is possible that cable damage could occur prior to system actuation. Therefore, it is likely that the OMA will need to be performed in the event of a fire in FA 43. The OMA will be successful for the following reasons:

FA 43 (fire initiating area) and FA 36 (action area) are located in physically separate buildings. No fire effects from a fire in an EDG room would impact a switchgear room.

The travel and performance time for this action is nine minutes. There are 60 minutes allotted for this action. Even with a 30-minute diagnosis time, there is adequate time with a 100% margin to perform this action.

The action involves simply operating a manual transfer switch. This is a task that an operator is familiar with and performs frequently.

This is the only OMA for a fire in FA 43.

Action U - Restoration of Offsite Power to the Unit 2 E12, E22, E32 and E42 4kV Busses There is the potential for any of the four diesel generator output breakers to spuriously close, rendering the bus unavailable until the diesel generator breaker is opened and the lockouts reset. There is a cable associated with each of the four 4kV busses routed through Fire Area (FA) 50. All four of these cables are routed in room 126, located on elevation 116', common area of the Turbine Building. The four cables associated with the Unit 2 4kV busses that are routed in the room are; bus E12 breaker cable ZA2A1503E; bus E22 breaker cable ZB2A1606E; bus E32 breaker ZC2A1704E and bus E42 breaker cable ZD2A1807E. Loss of any one of these cables will only affect the associated 4kV bus. The breaker cable for the E12 bus ("A" train) and the breaker cable for the E32 bus ("C" train) were originally encapsulated in Thermo-lag since the "A" train powered RCIC and to maintain one EDG (to power RHR). The "C" train was encapsulated by Thermo-lag to maintain a second EDG (also to power RHR). The manual action was created so that Thermo-lag did not need to be upgraded. Modification P00703 determined that a simple manual action could be performed to restore the 4kV busses; therefore, it was decided to restore all four buses to provide defense-in-depth. If cables ZA2A1503E and ZC2A1704E survive the fire, power will be maintained to the E12 and E32 busses which are necessary for safe shutdown.

The fire hazards analysis will address the relative location of the cables to each other, consider fire protection features, exposing combustibles and potential ignition sources.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 26 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas Fire Hazards Analysis Cable Locations Cable ZA2A1503E enters Fire Area (FA) 50 at the ceiling of room 126 from the E12 Switchgear Room (FA 39), room 227, elevation 135'. The cable is routed in conduit which remains encapsulated in abandoned thermo-lag. The conduit is routed from the ceiling of elevation 116' straight down to a junction box located just above the floor. The conduit is encapsulated in abandoned Thermo-lag from the time it enters the room to the point where the conduit enters the junction box. This junction box remains encapsulated in abandoned Thermo-lag. Cable ZA2A1503E exits the junction box in conduit for approximately 15 inches where the conduit becomes embedded in the floor. This section of conduit is not encapsulated in abandoned Thermo-lag for this short distance but is not exposed by the 13kV switchgear since it is at the floor level.

Cable ZB2A1606E enters Fire Area (FA) 50 at the ceiling of room 126 from the E22 Switchgear Room (FA 37), room 231, elevation 135'. The cable is routed in conduit. The conduit is routed from the ceiling of elevation 116' straight down to a junction box located just above the floor.

Cable ZB2A1606E exits the junction box in conduit for approximately 15 inches where the conduit becomes embedded in the floor. None of the conduits or the junction box has raceway encapsulation.

Cable ZC2A1704E enters FA 50 at the ceiling of room 126 from the E32 Switchgear room (FA 38), room 217, elevation 135'. The cable is routed in conduit through FA 50, room 126 horizontally approximately 30 feet to a junction box. This conduit is encapsulated in abandoned Thermo-lag from the point where it enters FA 50 at the ceiling, to the point where the conduit enters the junction box. The Thermo-lag has been removed from the junction box door, but remains on the sides. Cable ZC2A1704E exits the junction box in conduit which is routed straight down 22 inches where it becomes embedded in the floor slab. This 22-inch section of exposed conduit is not encapsulated with abandoned Thermo-lag for this short distance but is not exposed by the 13kV switchgear or other combustible materials.

Cable ZD2A1807E enters FA 50 at the ceiling of room 126 from the E42 Switchgear room (FA 36), room 226 elevation 135'. The cable is routed in conduit through FA 50, room 126 horizontally approximately 50 feet to a junction box. Cable ZD2A1807E exits the junction box in conduit which is routed straight down 22 inches where it becomes embedded in the floor slab.

Neither the conduit nor the junction box containing cable ZD2A1807E are located within raceway encapsulation.

As noted above, only the ZA2A1503E and ZC2A1704E cables are necessary to power the busses credited for safe shutdown. All four busses are restored since that provides defense-in-depth and operational flexibility.

Cables ZA2A2503E and ZC2A1704E are routed in conduits that remain encapsulated in abandoned Thermo-lag for their entire routing through FA 50. The only exception is the Thermo-lag that has been removed from the door of the junction box located on the south wall

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 27 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas of room 126. However, this junction box has a ventless metal door that will provide exposure protection until the sprinkler system actuates.

The abandoned Thermo-lag was considered to have a three-hour fire resistance rating when originally installed. Subsequently, it was determined that the three-hour Thermo-lag material as originally installed at PBAPS had a fire resistance rating closer to one hour. This Thermo-lag was abandoned in place and remains intact for the entire route, except for on the door of the junction box and conduits leaving the junction box and dropping a short distance to the floor, as noted above. No upgrades or modifications were performed on this section of Thermo-lag, so a fire resistance rating is not being specified. However, the existing abandoned Thermo-lag will provide sufficient protection to the cables until the pre-action system can actuate.

Fire Protection Systems As previously noted, FA-50 includes most of the Unit 2 and Unit 3 turbine building. This is a large fire area containing a number of rooms on several elevations. However, the routing of the cables for this OMA through FA 50 is limited to room 126. The fire hazards analysis can be limited to room 126 since a fire originating elsewhere in the Turbine Building is unlikely to spread into room 126. This room contains a full room smoke detection system with spacing compliant with NFPA 72. In addition, a full room pre-action sprinkler system with sprinkler head placement compliant with NFPA 13 is provided in room 126. There is an automatic sprinkler system in the adjacent open areas of the Turbine Building. The remainder of the Turbine Building is separated from this room by heavy concrete radiation barriers and a water curtain (which is part of the room 126 pre-action system) at the doorways. The west wall is a three-hour rated fire area boundary. The automatic sprinkler system, pre-action sprinkler system and smoke detection system are addressed by the PBAPS Technical Requirements Manual (TRM)

(which is part of the UFSAR). The TRM specifies a testing frequency and compensatory measures should the system become inoperable. There are portable fire extinguishers and hose stations for use by the fire brigade for manual fire fighting located in and near this room.

Exposing combustibles The combustible loading in the fire zone that contains room 126 is considered to be low, (an equivalent fire severity of 45 minutes or less). Combustibles in the room include fire retardant cable insulation, Thermo-lag and various Class A combustible materials. None of the combustible materials located in the room would create a high heat release rate fire.

Ignition sources This room contains two rows of 13kV switchgear cabinets. The conduits containing the cables ZC2A1704E and ZD2A1807E cross directly above (approximately five feet) these 13kV switchgear cabinets. (The 13kV switchgear cabinets run east-west and the conduits are routed in a north-south direction.) The conduits are assumed to be located with the anticipated heat plume in the event of a 13kV switchgear failure. The conduit that contains cable ZC2A1704E remains encapsulated with abandoned Thermo-lag. The conduits containing cables ZA2A1503E and ZB2A1606E are routed from the ceiling directly to the floor and do not travel over the 13kV switchgear cabinets. These conduits would not be within the projected heat plume from a 13kV switchgear failure. Hot work activities in this area are infrequent and

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 28 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas administrative controls (e.g. hot work permits, fire watch, supervisory controls) are in place if hot work activities do take place.

Summary Room 126 is separated from the remainder of the Turbine Building by heavy concrete radiation barriers, automatic sprinklers and water curtains. The conduits containing the cables associated with the OMA are provided various levels of separation and protection that provide reasonable assurance that the cables will not be damaged prior to the actuation of the pre-action sprinkler system in the area.

The conduit containing cable ZA2A1503E remains encapsulated in abandoned Thermo-lag.

Since this Thermo-lag was not upgraded, no specific fire resistance rating is given, but there is reasonable assurance that the Thermo-lag, as currently installed will protect the cable until the pre-action sprinkler system actuates. This cable is not routed over the 13kV switchgear and would not be exposed to the heat plume from a 13kV switchgear failure.

The conduit containing cable ZB2A1606E is not encapsulated. This conduit does not run above the 13kV switchgear and would not be exposed to the heat plume from a 13kV switchgear failure. The conduit containing this cable is located within 5 feet of the conduits containing cables ZA2B1503E and ZD2A1807E. However, the conduit would provide some level of protection until the pre-action sprinkler system actuated.

The conduit containing cable ZC2A1704E remains encapsulated in abandoned Thermo-lag.

Since this Thermo-lag was not upgraded, no specific fire resistance rating is given, but there is reasonable assurance that the Thermo-lag as currently installed will protect the cable until the pre-action system actuates. The door of the junction box has had the Thermo-lag removed, but the door remains a metal ventless door that will provide protection to the cables within the junction box. This junction box is not directly exposed by the 13kV switchgear.

The conduit containing cable ZD2A1807E is not encapsulated. This conduit runs above the 13kV switchgear and would be subject to damage in the event of a 13kV switchgear failure prior to the actuation of the sprinkler system. The conduit is at one point located within approximately 5 feet of the conduits containing ZA2A1503E and ZB2A1606E. However, this point is not over the 13kV switchgear and the conduits are in a vertical alignment at this point. It is unlikely that a fire would damage all three cables prior to actuation of the pre-action sprinkler system.

The defense-in-depth features that mitigate the potential for a fire damaging the cables associated with this OMA include:

Smoke detection system in the area that initiates the pre-action sprinkler system and provides a control room alarm, Pre-action sprinkler system, and Abandoned, but intact Thermo-lag protects the cables that are needed to ensure power to the "A" and "C" train switchgear to power credited shutdown components.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 29 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas Therefore, the likelihood of need to perform the manual action is low.

If the manual actions are necessary, an action is performed in each of the Unit 2 4kV Switchgear rooms. These rooms can be accessed via the Radwaste Corridor and will not be impacted by a fire in the Turbine Building room 126. The switchgear rooms have a separate ventilation system from the Turbine Building. The actions are provided to line up power for the battery chargers. Battery power is conservatively estimated to last 60 minutes. A delay in completing this task would not adversely impact safe shutdown.

Action V - Restoration of Offsite Power to the Unit 3 E13, E23, E33 and E43 4kV Busses There is the potential for any of the four diesel generator output breakers to spuriously close, rendering the bus unavailable until the diesel generator breaker is opened and the lockouts reset. There is a cable associated with each of the four 4kV busses routed through Fire Area (FA) 50. All four of these cables are routed in room 126, located on elevation 116', common area of the Turbine Building. The four cables associated with the Unit 2 4kV busses that are routed in the room are; bus E13 breaker cable ZA3A1503E; bus E23 breaker cable ZB3A1606E; bus E33 breaker cable ZC3A1704E and bus E43 breaker cable ZD3A1807E.

Loss of any one of these cables will only affect the associated 4kV bus. The breaker cable for the E13 bus ("A" train) and the breaker cable for the E33 bus ("C" train) were originally encapsulated in Thermo-lag since the "A" train powered RCIC and to maintain one EDG (to power RHR). The "C" train was encapsulated by Thermo-lag to maintain a second EDG (also to power RHR). The manual action was created so the Thermo-lag did not need to be upgraded.

Modification P00703 determined that a simple manual action could be performed to restore the 4kV busses; therefore, it was decided to restore all four buses to provide defense-in-depth. If cables ZA3A1503E and ZC3A1704E survive the fire, power will be maintained to the E13 and E33 busses which are necessary for safe shutdown.

The fire hazards analysis will address the relative location of the cables to each other, consider fire protection features, exposing combustibles and potential ignition sources.

Fire Hazards Analysis Cable Locations Cable ZA3A1503E enters Fire Area (FA) 50 at the ceiling of room 126 from the E12 Switchgear Room (FA 39), room 227, elevation 135'. The cable is routed in conduit which remains encapsulated in abandoned thermo-lag. The conduit is routed from the ceiling of elevation 116' straight down to a junction box located just above the floor. The conduit is encapsulated in abandoned Thermo-lag from the time it enters the room to the point where the conduit enters the junction box. This junction box remains encapsulated in abandoned Thermo-lag. Cable ZA3A1503E exits this junction box in conduit for approximately 15 inches where the conduit becomes embedded in the floor. This conduit is not encapsulated in abandoned Thermo-lag for this short distance, however it is not exposed by the 13kV switchgear or other combustible materials.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 30 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas Cable ZB3A1606E enters Fire Area (FA) 50 at the ceiling of room 126 from the E22 Switchgear Room (FA 37), room 231, elevation 135'. The cable is routed in conduit. The conduit is routed from the ceiling of elevation 116' straight down to a junction box located just above the floor.

Cable ZB3A1606E exits the junction box in conduit for approximately 15 inches where the conduit becomes embedded in the floor. None of the conduits or the junction box associated with this cable is encapsulated.

Cable ZC3A1704E enters FA 50 at the ceiling of room 126 from the E32 Switchgear room (FA 38), room 217, elevation 135'. The cable is routed in conduit through FA 50, room 126 horizontally approximately 30 feet to a junction box. This conduit is encapsulated in abandoned Thermo-lag from the point where it enters FA 50 at the ceiling to the point where the conduit enters the junction box. The Thermo-lag has been removed from the junction box door, but remains on the sides. Cable ZC2A1704E exits the junction box in conduit which is routed straight down 22 inches where it becomes embedded in the floor slab. This 22 inch section of exposed conduit is not encapsulated with abandoned Thermo-lag, but is not exposed by the 13kV switchgear or other combustible materials.

Cable ZD3A1807E enters FA 50 at the ceiling of room 126 from the E42 Switchgear room (FA 36), room 226 elevation 135'. The cable is routed in conduit through FA 50, room 126 horizontally approximately 50 feet to a junction box. Cable ZD3A1807E exits this junction box in conduit which is routed straight down 22 inches where it becomes embedded in the floor slab.

Neither the conduits nor the junction box are encapsulated.

As noted above, only the ZA3A1503E and ZC3A1704E cables are necessary to power the busses credited for safe shutdown. All four busses are restored since that provides defense-in-depth and operational flexibility.

Cables ZA3A2503E and ZC3A1704E are routed in conduit that remain encapsulated in abandoned Thermo-lag for their entire routing through FA 50. The only exception is the Thermo-lag that has been removed from the door of a junction box on the south wall of room 126 and the short sections of conduit from the junction box to the floor. However, this junction box has a ventless metal door that will provide exposure protection until the sprinkler system actuates. The sections of conduit near the floor will not be exposed to heat from a 13kV switchgear failure or other fire condition due to their proximity to the floor.

The abandoned Thermo-lag was considered to have a three-hour fire resistance rating when originally installed. Subsequently, it was determined that the three-hour Thermo-lag material as originally installed at PBAPS had a fire resistance rating closer to one hour. This Thermo-lag was abandoned in place and remains intact for the entire route, except for on the door of the junction box and conduits leaving the junction box and dropping a short distance to the floor, as noted above. No upgrades or modifications were performed on this section of Thermo-lag, so a fire resistance rating is not being specified. However, the existing abandoned Thermo-lag will provide sufficient protection to the cables until the pre-action system can actuate.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 31 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas Fire Protection Systems As previously noted, FA-50 is a large fire area containing a number of rooms on several elevations. However, the routing of the cables for this OMA through FA 50 is limited to room 126. The fire hazards analysis can be limited to room 126 since a fire originating elsewhere in the Turbine Building is unlikely to spread into room 126. This room contains a full room smoke detection system with spacing compliant with NFPA 72. In addition, a full room pre-action sprinkler system with sprinkler head placement compliant with NFPA 13 is provided in room 126. There is an automatic sprinkler system in the adjacent open areas of the Turbine Building.

The remainder of the Turbine Building is separated from this room by heavy concrete radiation barriers and a water curtain (which is part of the room 126 pre-action system) at the doorways.

The west wall is a three-hour rated fire area boundary. The automatic sprinkler system, pre-action sprinkler system and smoke detection system are addressed by the PBAPS Technical Requirements Manual (TRM) (which is part of the UFSAR). The TRM specifies a testing frequency and compensatory measures should the system become inoperable. There are portable fire extinguishers and hose stations for use by the fire brigade for manual fire fighting located in and near this room.

Exposing combustibles The combustible loading in the fire zone that contains room 126 is considered to be low (an equivalent fire severity of 45 minutes or less). Combustibles in the room include cable insulation, Thermo-lag and various Class A combustible materials. None of the combustible materials located in the room would create a high heat release rate fire.

Ignition sources This room contains two rows of 13kV switchgear cabinets. The conduits containing the cables ZC2A1704E and ZD2A1807E cross directly above (approximately five feet) these 13kV switchgear cabinets. (The 13kV switchgear cabinets run east-west and the conduits are routed in a north-south direction.) The conduits are assumed to be located with the anticipated heat plume in the event of a 13kV switchgear failure. Conduit ZC2B126 containing cable ZC3A1704E remains encapsulated with abandoned Thermo-lag. The conduits containing cables ZA3A1503E and ZB3A1606E are routed from the ceiling directly to the floor and do not travel over the 13kV switchgear cabinets. These conduits would not be within the projected heat plume from a 13kV switchgear failure. Hot work activities in this area are infrequent and administrative controls (e.g. hot work permits, fire watch, supervisory controls) are in place if hot work activities do take place.

Summary Room 126 is separated from the remainder of the Turbine Building by heavy concrete radiation barriers, automatic sprinklers and water curtains. The conduits containing the cables associated with the OMA are provided various levels of separation and protection that provide reasonable assurance that the cables will not be damaged prior to the actuation of the pre-action sprinkler system in the area.

The conduit containing cable ZA3A1503E remains encapsulated in abandoned Thermo-lag.

Since this Thermo-lag was not upgraded, no specific fire resistance rating is given, but there is

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 32 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas reasonable assurance that the Thermo-lag, as currently installed will protect the cable until the pre-action sprinkler system actuates. This cable is not routed over the 13kV switchgear and would not be exposed to the heat plume from a 13kV switchgear failure.

The conduit containing cable ZB3A1606E is not encapsulated. This conduit does not run above the 13kV switchgear and would not be exposed to the heat plume from a 13kV switchgear failure. The conduit containing this cable is located within 5 feet of the conduits containing cables ZA3B1503E and ZD3A1807E. However, the conduit would provide some level of protection until the pre-action sprinkler system actuated.

The conduit containing cable ZC3A1704E remains encapsulated in abandoned Thermo-lag.

Since this Thermo-lag was not upgraded, no specific fire resistance rating is given, but there is reasonable assurance that the Thermo-lag as currently installed will protect the cable until the pre-action system actuates. The door of the junction box has had the Thermo-lag removed, but the door remains a metal ventless door that will provide protection to the cables within the junction box. This junction box is not directly exposed by the 13kV switchgear.

The conduit containing cable ZD3A1807E is not encapsulated. This conduit runs above the 13kV switchgear and would be subject to damage in the event of a 13kV switchgear failure prior to the actuation of the sprinkler system. The conduit is at one point located within approximately 5 feet of the conduits containing ZA3A1503E and ZB3A1606E. However, this point is not over the 13kV switchgear and the conduits are in a vertical alignment at this point. It is unlikely that a fire would damage all three cables prior to actuation of the pre-action sprinkler system.

The defense-in-depth features that mitigate the potential for a fire damaging the cables associated with this OMA include:

Smoke detection system in the area that initiates the pre-action sprinkler system and provides a control room alarm, Pre-action sprinkler system, and Abandoned, but intact Thermo-lag protects the cables that are needed to ensure power to the "A" and "C" train switchgear to power credited shutdown components.

Therefore, the likelihood of need to perform the manual action is low.

If the manual actions are necessary, an action is performed in each of the Unit 3 4kV Switchgear rooms. These rooms can be accessed via the Radwaste Corridor and will not be impacted by a fire in the Turbine Building room 126. The switchgear rooms have a separate ventilation system from the Turbine Building. The actions are provided to line up power for the battery chargers. Battery power is conservatively estimated to last 60 minutes. A delay in completing this task would not adversely impact safe shutdown.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 33 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas Action Y - Transfer of SU-25 Breaker to Auxiliary Equipment to Alternate Power Source The SU-25 breaker auxiliaries are fed from two different diesel backed 480V motor control centers (MCC) with an automatic transfer switch between the two power supplies. Automatic transfer switch 00B080 feeds the SU-25 auxiliaries and it is in turn fed by alternate power supply breaker 00B5312 (via transformer 0AX048) and normal power supply MCC breaker 00B5612 (via transformer 0BX048). Additionally, there is a third source of power (00L207) to the SU-25 auxiliaries via a manual transfer switch (00S306) which is the supply available following the Action Y. Cables that feed both MCC 00B53 and MCC 00B56 are located in Fire Area 50, Turbine Building. Loss of cable ZA2B1021B will result in the loss of MCC 00B53. Loss of cables ZD3B1321B or ZD3A1321D will result in the loss of MCC 00B56. The fire hazards analysis will address the relative location of the cables to each other; consider fire protection features, exposing combustibles and potential ignition sources.

Fire Hazards Analysis Cable Locations Cable ZA2B1021B enters Fire Area (FA) 50 at the ceiling of room 126 from the E12 Switchgear Room (FA 39), room 227, elevation 135'. The cable is routed in conduit which remains encapsulated in abandoned thermo-lag. The conduit is routed south approximately 50 feet until the encapsulated conduit enters a junction box (the conduit remains encapsulated within the junction box. The cable remains in conduit as it exits the junction box and goes approximately 18 inches to the floor where it becomes embedded in the floor slab. The 18 inches of conduit from the bottom of the junction box to the floor slab does not have encapsulation.

Cable ZD3B1321B enters FA 50 at the ceiling of room 126 from the E42 Switchgear room (FA 36), room 226, elevation 135'. The cable is routed in conduits through FA 50, room 126 approximately 50 feet to a junction box. The cable exits the junction box in conduit and drops 18 inches to the floor where the conduit becomes embedded in the floor slab.

Cable ZD3B1321D follows the same routing as cable ZD3B1321B as described above and actually is routed in the same conduits for the entire routing in FA 50.

For the purpose of maintaining the function of power to the SU-25 auxiliaries, cable ZA2B1021B needs to be separated from cables ZD3B1321B and ZD3A1321D.

The conduit containing cable ZA2B1021B and conduits containing cables ZD3B1321B and ZD3A1321D are routed parallel to one another, generally within five feet as they pass through fire area 50. The conduit containing cable ZA2B1021B is encapsulated with Thermo-lag for the entire routing through FA 50, including into and through a junction box. This Thermo-lag was considered to have a three-hour fire resistance rating when installed. Subsequently, it was determined that the three-hour Thermo-lag material as originally installed at PBAPS had a fire resistance rating closer to one hour. This Thermo-lag was abandoned in place and remains intact for the entire route, except for the last 18 inches from the bottom of the junction box to the point where the conduit is embedded in the floor slab. No upgrades or modifications were

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 34 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas performed on this section of Thermo-lag, so a specific fire resistance rating is not being specified.

It is important to note that this section of Thermo-lag was not upgraded since the OMA is a simple action that takes place in a building outside the power block that would not see any fire effects and there is ample time to perform the action.

Fire Protection Systems As previously noted, FA-50 is a large fire area containing a number of rooms on several elevations. However, the routing of the cables for this OMA through FA 50 is limited to room 126. The fire hazards analysis can be limited to room 126 since a fire originating elsewhere in the Turbine Building is unlikely to spread into room 126. This room contains a full room smoke detection system with spacing compliant with NFPA 72. In addition, a full room pre-action sprinkler system with sprinkler head placement compliant with NFPA 13 is provided in room 126. There is an automatic sprinkler system in the adjacent open areas of the Turbine Building.

The remainder of the Turbine Building is separated from this room by heavy concrete radiation barriers and a water curtain (which is part of the room 126 pre-action system) at the doorways.

The west wall is a three hour rated fire area boundary. The automatic sprinkler system, pre-action sprinkler system and smoke detection system are addressed by the PBAPS Technical Requirements Manual (TRM) (which is part of the UFSAR). The TRM specifies a testing frequency and compensatory measures should the system become inoperable. There are portable fire extinguishers and hose stations for use by the fire brigade for manual fire fighting located in and near this room.

Exposing combustibles The combustible loading in the fire zone that contains room 126 is considered to be low (an equivalent fire severity of 45 minutes or less). Combustibles in the room include cable insulation, Thermo-lag and various Class A combustible materials. None of the combustible materials located in the room would create a high heat release rate fire.

Ignition sources This room contains 13kV switchgear cabinets. The conduits containing the cables associated with this OMA are routed directly above (approximately 5 feet) these 13kV switchgear cabinets.

The conduits are assumed to be located within the anticipated heat plume in the event of a 13kV switchgear failure. Hot work activities in this area are infrequent and administrative controls (e.g. hot work permits, fire watch, supervisory controls) are in place if hot work activities do take place.

Summary Room 126 is separated from the remainder of the Turbine Building by heavy concrete radiation barriers, automatic sprinklers and water curtains. The conduits containing the cables associated with the OMA are provided various levels of separation and protection that provide reasonable assurance that the cables will not be damaged prior to the actuation of the pre-action sprinkler system in the area.

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 35 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas The conduits containing the cables associated with the OMA are routed in close proximity to one another. A single fire, such as could occur during a 13kV switchgear failure, could expose both conduits at the same time. The conduit containing cable ZA2B1021B remains encapsulated in Thermo-lag for the entire length above the 13kV switchgear. While this Thermo-lag no longer has a specific fire resistance rating, Thermo-lag with similar design and installation features is considered to have a one-hour fire resistance rating. There is a high degree of confidence that the existing Thermo-lag encapsulation will provide protection to cable ZA2B1021B in the event of a 13kV switchgear failure until the pre-action sprinkler system actuates.

There is a small section of Thermo-lag that was removed from conduit containing cable ZA2B1021B as it leaves the junction box until it enters the floor slab. This section of conduit is directly adjacent to the conduit which contains cables ZD3B1321B and ZD3B1321D. These conduits leave the junction box and go straight down approximately 18 inches into the floor slab.

These conduits are not exposed by the 13kV switchgear or any other ignition source. The conduits are at floor level and will not immediately be exposed to heat from a fire in the area.

The conduit will provide some level of protection to the cables until the pre-action sprinkler system actuates.

The defense-in-depth features that mitigate the potential for a fire damaging both cables associated with this OMA include:

Smoke detection system in the area that initiates the pre-action sprinkler system and provides a control room alarm, Pre-action sprinkler system, and Abandoned, but intact Thermo-lag protecting one of the cables.

Therefore, the likelihood of need to perform the manual action is low.

Action BB - Transfer of Battery Charger 3DD003 to Alternate Power Source A fire in Fire Area 58 has the potential to damage cables ZD3A1806A and ZD3B3983A. The loss of either of these cables will result in a loss of the normal power supply to the 3DD003 battery charger. The battery charger is needed to maintain long term DC power through the station batteries. The amount of time the batteries can operate prior to initiation of recharging is 60 minutes, which is a conservative estimate. Battery charger 3DD003 can also be fed from another power source. The alternate power source is routed in separate fire areas so a single fire cannot damage both the normal and alternate power feed. The manual action is required to transfer the alternate power supply to the battery charger. This action is to first close a breaker and then simply operate a manual transfer switch; both are located in the E43 4kV Switchgear room which is a separate fire area (FA 34). This battery charger has a single normal feed, with the alternate source from the other unit. Therefore, an automatic transfer switch cannot be used. Since the normal feed and the alternate power supplies are routed in separate fire areas, one power supply will always be available. The fire hazards analysis below will address the two cables routed in Fire Area 58 that are associated with the normal power feed to the battery

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 36 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas charger. The fire hazards analysis will address the cable locations, consider fire protection features, exposing combustibles and potential ignition sources. Since the loss of either cable will result in the loss of the normal feed to the battery charger, the FHA will not address the separation of these two cables from each other.

Battery Charger 3DD003 is located in FA 34, the E43 Switchgear Room.

Fire Hazards Analysis Cable Locations Cable ZD3A1806A enters FA 58 through the south wall (from a separate fire area) in conduit.

The conduit is routed north across the room to the north wall. When the conduit reaches the north wall, it turns up and goes through the ceiling to a separate fire area above. This conduit travels over the MG set.

Cable ZD3B3983A enters FA 58 through the east wall (from a separate fire area) in conduit.

The conduit travels west through the room paralleling the north wall. The cable exits the conduit and enters a vertical cable tray attached to the north wall and rises up to the ceiling where the cable penetrates into a separate fire area located above. The conduit and tray never cross over the MG set.

FA 58 is the Unit 3 Recirculation Pump MG set room (room 258) located on the 135' elevation of the Radwaste Building. The manual action is performed in the E43 Switchgear room which is a separate fire area (FA 34) located in the turbine building. A fire in FA 58 will have no impact on the operator performing the actions in the switchgear room.

Fire Protection Systems FA-58 is the Unit 3 Recirculation Pump MG set room. This room has a floor area of 3525 sq. ft and a height of approximately 29 feet. The room is provided with a pre-action sprinkler system that is designed to provide localized protection to the MG set. The sprinkler system heads are located over the MG set itself and not at the ceiling. This is not considered to be an area-wide system and is not considered to be in compliance with NFPA 13 sprinkler head spacing for an area-wide system. This system was an original plant installation and is provided for localized protection of the MG set. The pre-action system is actuated automatically by any one of the six smoke detectors in the room. These smoke detectors are located directly above the MG set and are not located at the ceiling, so compliance with NFPA 72 is not provided. Both the pre-action sprinkler system and the smoke detection system are addressed by the PBAPS Technical Requirements Manual (TRM) (which is part of the UFSAR). The TRM specifies a testing frequency and compensatory measures should the systems become inoperable. There are portable fire extinguishers and manual hose stations located outside the room.

Exposing Combustibles The combustible loading in FA 26 is considered to be moderate (an equivalent fire severity of 45 minutes to 105 minutes). The primary combustible material in the area is lube oil from the MG set. Other combustible materials in the area include cable insulation, which is fire retardant, and

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 37 of 37 Docket Nos. 50-277 and 50-278 Fire Hazards Analyses for Operator Manual Action Initiating Fire Areas Thermo-lag. A fire involving the lube oil could create a high heat release rate that could damage the cables.

Ignition Sources The MG set is an ignition source as well as MCCs located within the room. This is not a shop area so hot work activities are infrequent and administrative controls (e.g., hot work permits, fire watch, supervisory controls) are in place if hot work activities do take place.

Summary The normal power supply and the alternate power supply for the 3DD003 battery charger are routed in separate fire areas so one source will be available in the event of a fire in FA 58. A manual action is required to tie in the alternate power supply which involves closing a breaker and operating a manual transfer switch, also located in a different fire area. This fire hazards analysis considered the two cables associated with the normal power supply to the 3DD003 battery charger. Due to the fire potential from both the combustible hazard (lube oil) and the ignition source (the MG set), it is possible that a fire in FA 58 could result in damage to the cables prior to detection and actuation of the pre-action sprinkler system.

The impact of the fire on the ability to perform this action is low. FA 58 has a separate ventilation system from the switchgear rooms (FA 33 and FA 38). There are 60 minutes to perform this action which only takes 12 minutes to perform. The batteries primarily provide DC control power for breaker manipulation. Since the breakers will be in the correct position at the end of the first hour for shutdown conditions, a delay in performing this task will not impact safe shutdown.

ATTACHMENT 3 10 CFR 50.12 Exemption Request Peach Bottom Atomic Power Station, Units 2 and 3 Docket Nos. 50-277 and 50-278 Request for Exemption from 10 CFR 50, Appendix R, Section III.G, Fire Protection of Safe Shutdown Capability" Withdrawal of Certain Operator Manual Actions from the Exemption Request

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 1 of 2 Docket Nos. 50-277 and 50-278 Withdrawal of Certain Operator Manual Actions from the Exemption Request At the time the original request for exemption was submitted (Reference 1), regulatory guidance concerning the types of OMAs that required exemption from Appendix R,Section III.G.2 had not yet been finalized. In October 2009, Regulator Guide (RG) 1.189, Revision 2 was issued. RG 1.189, Rev. 2 provides guidance relative to equipment on the hot shutdown success path (i.e.,

equipment required to achieve and maintain hot shutdown), versus equipment that is important to safe shutdown. Section 5.3.1.3 states, When one of the redundant safe-shutdown trains in a fire area is maintained free of fire damage by one of the means specified in Regulatory Position 5.3.1.1, then the use of operator manual actions may be credited with mitigating fire-induced operation or maloperation of components that are not part of the protected success path.

Based on this guidance, Exelon has re-evaluated the OMAs that were the subject of the original exemption request and determined that certain of the OMAs are credited with mitigating fire-induced operation or maloperation of components that are not part of the protected success path, and as a result, are not within the scope of Appendix R,Section III.G.2. Therefore, Exelon hereby withdraws these OMAs from the exemption request. The specific OMAs being withdrawn and the reasons for their withdrawal are described below.

Operator manual actions A, E, F, L, N, P, Q, Z, AA, DD, EE, FF and GG are all examples of actions that result from fire-induced failures of important to safe shutdown components, as described in section 5.3.1.5, Examples of SSCs Important to Safe Shutdown.

Actions A, F, L, P, Q, Z, AA, DD, EE and FF are all actions that involve restoration of instrumentation, which supplements safe shutdown equipment, but is not necessary to restore or operate safe shutdown equipment. In each case redundant or complementary instrumentation is available for key shutdown parameters without the restoration of this instrumentation performed by these manual actions. None of these actions restores equipment needed to achieve hot shutdown. The restoration of additional instrumentation provides the operators in the control room with additional information on plant conditions that is useful, but not required, in the process of post-fire safe shutdown.

Actions E and GG involve actions to remove a false LOCA signal on the unaffected Unit which does not impact the ability to achieve shutdown on the affected unit. The False-LOCA signal occurs on the opposite unit as an anticipated part of shutting down the opposite unit. The signal is assumed to be generated on the opposite unit as a result of high drywell pressure signal caused by the assumed loss of drywell cooling on the opposite unit, combined with the low reactor pressure signal caused by depressurizing the opposite unit to cold shutdown conditions.

The signal is not expected to occur until the opposite unit is depressurizing to make the transition to cold shutdown conditions. The action is taken on the unit that is transitioning to cold shutdown to prevent that unit's RHR logic from sending a trip signal to the other unit.

Manual actions are permissible to support transition to cold shutdown and maintaining cold shutdown without prior NRC approval via the exemption process.

Action N involves manual operation of MO-3-10-089A, which establishes high pressure service water flow through the "A" RHR heat exchanger. Since the "C" RHR loop is credited for safe shutdown, restoration of the "A" loop of RHR is not required for safe shutdown. This was a case of providing additional shutdown equipment available to the operators, with a simple manual

Response to Request for Additional Information 10 CFR 50, Appendix R, Section III.G.2 Exemption Request Page 2 of 2 Docket Nos. 50-277 and 50-278 Withdrawal of Certain Operator Manual Actions from the Exemption Request action to further enhance the redundancy and defense-in-depth of the shutdown methods available. This action does not need prior NRC approval.

Action W restores power to battery charger 2AD003 because the 480V motor control center (20B059) that normally feeds the battery charger originally failed the multiple high impedance fault criteria for Fire Area 50. Following a Plant modification, which increased the long time trip setpoint of 480V load center breaker (E124 (1014)) feeding the motor control center (20B059),

the motor control center no longer fails multiple high impedance criteria used at PBAPS. Motor control center 20B059 is not adversely impacted by a fire in Fire Area 50 and is available to support post fire safe shutdown activities; therefore, Manual Action W is no longer required.

The following table provides a list of each of the OMAs being withdrawn.

OMA Initiating Fire Area Description A

2 Transfer of Panel 20Y033 to Alternate Power Source E

4 Defeat Unit 2 RHR Logic Trip of 3B RHR Pump F

4 Transfer of Panel 20Y035 to Alternate Power Source L

27 Transfer of Panel 20Y035 to Alternate Power Source N

30 Local Manual Operation of MO-3-10-089A P

30 Transfer of Instrument Power Supply 30C144 Using Transfer Switch 30S546 Q

33 Transfer of Panel 30Y034 to Alternate Power Source W

50 Provide Alternate Power to 2A Battery Charger Z

57 Transfer of Instrument Power Supply 30C144 using Transfer Switch 30S546 AA 57 Transfer of Panel 30Y033 to Alternate Power Source DD 58 Transfer of Panel 30Y034 to Alternate Power Source EE 58 Transfer of Instrument Power Supply 30C144 using Transfer Switch 30S546 FF 58 Transfer of Panel 30Y033 to Alternate Power Source GG 58 Defeat Unit 3 RHR Logic Trip of 2D RHR Pump As a result of the OMAs listed above being withdrawn from the exemption request, the following fire areas are no longer applicable to the exemption request: Fire Areas 4, 27, 33, and 57.

Therefore, responses to the RAIs associated with these fire areas are no longer required.

References:

1. Letter from P. B. Cowan, Exelon Generation Company, LLC, to U.S. Nuclear Regulatory Commission, Request for Exemption from 10 CFR 50, Appendix R, Section III.G, Fire Protection of Safe Shutdown Capability, dated March 6, 2009.

2. Regulatory Guide 1.189, Revision 2, Fire Protection for Nuclear Power Plants, dated October 2009.