ML20117M652
| ML20117M652 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 06/13/1996 |
| From: | Graessar K COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| BYRON-96-0176, BYRON-96-176, NUDOCS 9606180689 | |
| Download: ML20117M652 (15) | |
Text
e-O>mmonwcalth Ediuin 0)mpany flyron Generating Marion 4 iso North German Cliurch Itoad U) ton,11. 61010779 i Tel H15-2M5 4 il 4
June 13,1996 LTR:
Byron 96-0176 FILE:
1.10.0101 U.S. Nuclear Regulatory Commission Washington, D.C. 20555 ATTENTION:
Document Control Desk
SUBJECT:
Byron Station Units 1 & 2 Actions taken in Response to Safe Shutdown Analysis Deficiencies NRC Docket Nos. 50-454 and 50-455
REFERENCE:
1) 6/4/96 Emergency Notification System call regarding identified deficiencies in the Safe Shutdown Analysis 2)
Letter from K. Kofron to NRC concerning Action Taken in Response to Safe Shutdown Analysis Deficiencies dated 6/12/96 On 6/13/96, it was discovered that the letter of Reference 2 was missing details of long term actions to be taken in regards to Fire Zone 3.2.B-1. This revised transmittal includes the missing information.
On 6/4/96, Byron Site Engineering concluded the existing Byron Fire Protection Report (FPR) Safe Shutdown Analysis (SSA) conclusions regarding the availability of Control Room Ventilation (VC) System after a fire in the fire zones 2.1-0, 3.28-1, j
11.4-0,11.4C-0,11.5-0 and 11.6-0 are incorrect. Detailed reviews performed at Byron Station identified that redundant safe shutdown cables from both trains of VC are currently located within the fire zones identified above and are not protected in accordance with the separation requirements of Section Ill.G of 10CFR50 Appendix R.
It was determined that the existing configuration was not in compliance with the requirements of Section Ill.G of 10CFR50 Appendix R and that this condition was i
reportable per 10CFR 50.72(b)(1)(ii). The Reference ENS phone notification was made to the NRC on 6/04/96 for a condition outside the design basis for the plant.
Additional details related to these deficiencies were discussed with NRC staff members in conference calls held on June 6 and 7,1996. The purpose of this letter is to document the results of those discussions and the results of reviews completed since June 7.
ff 9606180609 960613 PDR ADOCK 050004S4 7[
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PDR J k A Unicom Company
Byron Ltr. 96-0176 June 13,1996 Page 2 A detailed explanation of these newly identified discrepancies for each of the six (6) fire zones is presented in Attachment A. Also included is an evaluation of the specific fire zones, short term compensatory actions, and the planned resolutions for these discrepancies.
Compensatory actions in the form of hourly firewatches, procedure verification, additional controls over transient combustibles and hot work, alternate cooling capability, and chift briefings have been initiated. These actions are presented in zone-specific manner in the Attachment. Additionally, the long term resolutions are detailed in the Attachment.
Additional vulnerabilities have been identified in one zone. Compensatory measures for this zone have been adjusted accordingly. The affected zone is Fire Zone 11.4-0.
Please address any questions to D. Brindle, Regulatory Assurance Supervisor, at (815) 234-5441 extension 2280.
Respectfully, K. L. Graes,e,r Site Vice President Byron Nuclear Power Station KLG/DB/rp cc. H. Miller, Administrator Region 111 1
G. Dick, Project Manager - NRR H. Peterson, Senior Resident inspector - Byron
e FIRE 7,0NE 2.1-0, MAIN CONTROI, ROOM:
Dgscriptign of fire zone:
Fire Za
-0 is located on Auxiliary Building Elevation 451 and includes the Main Control Room (MCR) t an row / columns L and P and 13 and 23 as shown ou Figure 2.3-8 of the Fire Protection Report (FPR). The fire zone includes both the Unit I and Unit 2 main control pancis. This zone is continuously manned by the control room operators. Also, ionization detectors in the supply and exhaust ductwork for the control pancis alarm in the MCR. The zone contains ionization detectors which annunciate and alarm in the Main Control Room (MCR). No automatic suppression systems are present in the zone.
Existina safe shutdown analysis discussion:
FPR Sections 2.4.2.4 (Unit 1) and 2.4.2.2 (Unit 2) discuss the safe shutdown analysis for this zone. Power and/or control cab!cs for redundant safe shutdown equipment are routed through this zone.
Instrument cables required to verify safe shutdown are also present in the zone. The current analysis describes an evaluation to evacuate the MCR due to the fire and to achieve safe shutdown outside of the MCR.
FPR revisions required to addresmrrpnt Control Room Ventilation (VC) system evaluations:
FPR Sections 2.4.2.4 and 2.4.2.2 do not list VC cables. Neither unit discusses the potential loss of both trains of the VC system due to a fire in this zone. In this zone, new cvaluations indicate that both VC Return Fans OA and OB would be disabled, along with redundant dampers such as both VC Supply Fan discharge dampers (OVC033Y, OVC172Y). When these recently identified additional VC safe shutdown components and cables are added to the analysis, both trains of VC become vulacrable to a fire in this zone. The redundant safe shutdown VC cables are routed to a MCR panel where control switches for both VC trains are located. The existing safe shutdown analysis for a fire in this zone assumes all control and instrumentation functions are kst and the evacua' ion of the MCR is required. This evaluation bounds a loss of ventilation in the MCR, except that the loss of VC results in the loss of cooling in the Aux Electric Equipment Rooms. This could affect instrumentation equipment in these rooms w hich could disablc mstrumentation indication at the Remote Shutdown Panel. If this should occur, instrumentation will still be available at the Fire Hazards Panels. Existing procedure BOA PRI-5 " Control Room Inaccessibility" incorporates utilization of the Fire Hazards Panel. FPR Sections 2.4.2.4 (Unit 1) and 2.4.2.2 (Unit 2) require a minor revision to discuss this alternate shutdown capability.
Co.msnsatory actions and long1rm resolutions:
The capability to safely shutdown following a fire in zone 2.10 is established by the existing evaluations for this zone. The loss of ventilation in the Aux Electric Equipment Rooms does not impact the current procedure (BOA PRI-5) for shutting down outside the MCR. Therefore, no compensatory actions or long term fixes are required.
4 1
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FIRE ZONE 3.2B-1. I OWER CABLE SPREADING AREA:
Rggriptiqn of fire zone:
Fire Zone 3.2B-1 is located on Auxiliary Building Elevation 439 and includes a portion of the lower cable spreading area between row / columns L and Q and 10 and 13 as shown on Figure 2.3-9 of the Fire Protection Report (FPR). The fire zone is located in the Unit I area of the Aux Building. The zone contains thermal ionization detectors which annunciate and alarm in the Main Control Room (MCR).
Automatic suppression (total flooding CO2 system) is present in this zone.
Existing safe shutdown analysis discussion:
FPR Section 2.4.2.8 (Unit 1) discusses the safe shutdown analysis for this zone. The existing analysis states power and/or control cables for only Division 12 are routed through this zone. Instrument cables for both channels of source range neutron monitoring are also present in the zone. The existing analysis takes credit for alternate source range monitoring at the Fire llazards Panel.
UR revisions reauired to address current Control Room Ventilation (VC) system evaluations:
FPR Section 2.4.2.8 does not list VC cables. It also does not discuss the potential loss of both trains of the VC system due to a fire in this zone. In this zone, new evaluations indicate that both VC Return Fans OA and OB would be disabled, along with redundant dampers such as both VC Supply Fan discharge dampers (OVC033Y,0VC172Y). When these recently identified additional VC safe shutdown components and cables are added to the analysis, both trains of VC become vulacrable to a fire in this zone. The redundant safe shutdown VC cables are routed in trays / conduits which are separated by a distance of 4 horizontal feet. This occurs at a single point of closest approach near column rows 10 and M where conduits containing Division i1 VC cables cross over cable trays containing redundant VC cables. The conclusion that both trains of VC are vulnerable to a fire in this zone will be added to the safe shutdown analyses for this zone. Although fire zone 3.2B-1 contains Division 12 cables, Division 12 power will be availabic to power the Fire Hazard Panel. Also, the alternate safe shutdown capability discussed below will be added to the FPR sections.
Allernate safe shutdown capability with the loss of the entire VC system:
Existing safe shutdown analyses for fires in the MCR and the Aux Electric Equipment Rooms bound the consequences of the loss of ventilation in these rooms. FPR Unit 1 Sections 2.4.2.4 & 2.4.2.21 and Uni!
l 2 Sections 2.4.2.2 & 2.4.2.20 currently evaluate the capability to achieve and maintain safe shutdown following a fire occurring in the Main Control Room Fire Zone 2.1-0 and the Aux Electric Equipmcat Rooms (fire zones 5.5-l&2). The fire in the MCR is assumed to disable control and instrumentation i
functions and force the evacuation of the MCR. The fire in the Aux Electric Equipment Rooms are assumed to disable redundant control and instrumentation functions. These existing evaluations for fire bound the consequences of the loss of ventilation to the MCR and the Aux Electric Equipment Rooms.
l These evaluations assume that instrumentation provided at the Fire Hazards Panel, IPL10J, is available.
The existing criteria for achieving safe shutdown following a fire in these zones are:
1.
Reactor is tripped and control rods inserted is verified prior to evacuation.
2.
Pressurizer safety valves provide over-pressure protection for hot standby and the PORV controls can be repaired and restored for later controlled depressurization. PORV block valves can be operated from their respective MCCs.
3.
Main Steam Relief valves will be operated locally using the hand hydraulic pumps.
2 i
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- 4. - Control of essential hot shutdown equipment can be achiew at the Remote Shutdown Panel and locally using BOA PRI-5 " Control Room Inaccessibility"and BOA ELECT-5 " Local Emergency Control of Safe Shutdown Equipment" 5.
Essential instrumentation indication is available at the Remote Shutdown and/or Fire llazards Panels.
6.
Contrcis for Rif can be repaired to achieve cold shutdown within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
Safe shutdown in fire zone 3.2B-1, if the 1 )ss of all VC should occur, will be demonstrated by applying the above criteria with the fellowing verifica3ons:
1.
Reactor is trippai anJ control rods inserted; the consequences of the loss of VC does not occar so fast that this verification cannot be made for a fire in this zone.
2.
Pressurizer safety valve fu'iction and capability to repair / operate the pressurizer PORVs or i.s block valves are not impahed as a result of a fire in this zone.
3.
I ocal manual operation of the main steam relief valves using the hand hydraulic pumps is not impaired as a result of a fire in this zone.
4.
Operation of the essential hot shutdown equipment utilizing BOA PRI 5 and BOA ELECT-5 is not impaired as a result of a fire in this zone.
5.
Essential instrumentation on the Unit 1 Fire Hazard Pancis is available for a fire in this zone since the installation of Thermo-L,ag resolution cable re-route modification in May 1996.
6.
Capability to repair / operate equipment necessary for residual heat removal is not impaired as a result of a fire in this zone.
Criteria 5 is met since the installation of reccat Thermo-lag resolution modifications and due to operating policies which establish that control of Division 12 switchgcar and miscellancous equipment room ventilation systems will be maintained in a " local" control mode. Operation in this mode will prevent fire induced faults from affecting the Division 12 ventilation train.
Compensatory actions and lonc term resolutions:
The capability to safely shutdown following a fire in zone 3.28-1 that results in the loss of ventilation in the MCR and Aux Electric Equipment Room is established by the bounding evaluations for fire in these rooms. Therefore, no long term fixes are required in this zone.
6 This Unit 1 Lower Cable Spreading Area has been made a transient combustible and hot work exclusion area. In the event that either transient combustibles must be present or hot work must be performed, a continuous fire watch will be established in this zonc, control cabics associated with the Unit 1 Division 12 switchgear and miscellaneous equipment room ventilation systems can be damaged by the fire. Byron station operates these systems in the " local" control mode which will isolate the cables of concern. Operation will be availabic at the local panel. Caution cards are placed at the appropriate locations to assure this operating configuration is maintained. The completion of the long term action for this zone discussed below will allow the removal of the caution cards and the reliance on this mode of operation.
The following long term action is being implemented as a long term solution:
A permanent design change to provide an alternate power source for the Unit 1 Fire llazards Panel from a Division 11 power source will be completed and installed no later than Refuel Outage BIR08.
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i FIRE ZONE 104-0. AUXILIARY BUILDING ELEVATION 383 FEET:
]
pescription of fire zone:
Fire Zone 11.4-0 is located on Auxiliary Building Elevation 383 and includes all of the general open-access arcas between row / columns L and W and 10 and 25 as shown on Figure 2.3-13 of the Fire Protection Report (FPR). The fire zone includes both Unit I and Unit 2 areas of the Aux Building. This j
zone secs normal foot traffic by site personnel performing activitics in the Auxiliary Building. The zone contains ionization detectors which annunciate and ala m in the Main Control Room (MCR). No automatic suppression systems are present except for automatic sprinklers prosided around a stairway at coordinates P-18.
Existina safe shutdown analysis discussion:
FPR Sections 2.4.2.43 (Unit 1) and 2.4.2.42 (Unit 2) discuss the safe shutdown analysis for this zone.
Powcr and/or control cables for redundant safe shutdown equipment are routed through this zone.
Instrument cables required to verify safe shutdown are also present in the zone. The existing analysis states Division 11 (Unit 1) and Division 21 (Unit 2) cables will be protected as necessary with fire rated barriers. The existing analysis is currently being resised to reflect re-routing of cables out of the zone to accomplish equivalent protection presiously provided by the Thermo-Lag fire barriers.
FPR rnisions rqqu. ire _d tg_ add gss current Control Room Ventilation (VC) systcru evaluations:
J FPR Section 2.4.2.42 (Unit 2) currently lists the routing of some redundant VC safe shutdown cables in zonc 11.4-0. Unit I does not list VC cables. Neither unit discusses the potential loss of both trains of the VC system due to a fire in this zone. In this zone, new evaluations indicate that both VC Return Fans 0A and 013 would be disabled, along with redundant dampers such as both VC Supply Fan discharge dampers (OVC033Y, OVC172Y). When these recently identified additional VC safe shutdown components and cables are added to the analysis, both trains of VC become vulnerable to a fire in this zone. The redundant safe shutdown VC cabics are routed in trays which are separated by a distance of approximately 10 feet.
This occurs at a single point of closest approach near column rows 17 and P. The conclusion that both trains of VC are vulnerable to a fire in this zone will be added to the safe shutdown analyses for this zone.
Also the alternate safe shutdown capability discussed below will be added to the FPR sections.
Alternatuafe shutdown capability with the loss of the entire VC system:
Existing safe shutdown analyses for fires in the MCR and the Aux Electric Equipment Rooms bound the i
consequences of the loss of ventilation in ther ens. FPR Unit 1 Sections 2.4.2.4 & 2.4.2.21 and Unit 2 Sections 2.4.2.2 & 2.4.2.20 currently evalum the capability to achieve and maintain safe shutdown following a fire occurring in the Main Control Room Fire Zone 2.1-0 and the Aux Electric Equipment Rooms (fire zones 5.5-l&2). The fire in the MCR is assumed to disable control and instrumentation funct ms and force the evacuation of the MCR. The fire in the Aux Electric Equipment Rooms are assumed to disable redundant control and instrumentation functions. These existing evaluations for fire bound the consequences of the loss of ventilation to the MCR and the Aux Electric Equipment Rooms.
Ilowever, these evaluations assume that instrumentation provided at the Fire Hazards Panels,1/2PL10J, is available. For a fire in this zone, Unit 1 Fire Hazard Panel will be powered from Division 12 as a result of a Thermo-Lag resolution cable re-route modification installed in May 1996. For a fire in this zone, Unit 2 Fire llazard Panel will not be available because of damage to the Division 22 power systems.
i The existing criteria for achiesing safe shutdown following a fire in these zones are:
1.
Reactor is tripped and control rods inserted is verified prior to evacuation.
l 4
2.
Pressurizer safety valves provide over-pressure protection for hot standby and the PORV controls can be repaired and restored for later controlled depressurization. PORV block valves can be operated from their respective MCCs.
3.
Main Steam Relief valves will be operated locally using the hand hydraulic pumps.
4.
Control of essential hot shutdown equipment can be achieve at the Remote Shutdown Panel and locally using BOA PRI-5 " Control Room Inaccessibility"and BOA ELECT-5 " Local i
Emergency Control of Safe Shutdown Equipment".
5.
Essential instrumentation indication is available at the Remote Shutdown and/or Fire Ilazards Panels.
6.
Controls for RH can be repaired to achieve cold shutdown within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
Safe shutdown in fire zone 11.4-0, if the loss of all VC should occur, will be demonstrated by applying the above criteria with the following verifications:
1.
Reactor is tripped and control rods inserted; the consequences of the loss of VC does not occur so fast that this verification cannot be made for a fire in this zone.
2.
Pressurizer safety valve function and capability to repair / operate the pressurizer PORVs or its block valves are not impaired as a result of a fire in this zone.
3.
Local manual operation of the main steam relief valves using the hand hydraulic pumps is not impaired as a result of a fire in this zone.
4.
Operation of the essential hot shutdown equipment utilizing BOA PRI-5 and BOA ELECT-5 is not impaired as a result of a fire in this zone.
5.
Essential instrumentation on the Unit i Fire Hazard Panel is now available for a fire in this zone For Unit 2, the Division 22 power supply for the Fire Hazard Panel will not be j
available, and therefore the panel will not be availabic.
6.
Capability to repair / operate equipment necessary for residual heat removal is not impaired as a result of a fire in this zone, i
The ability to safely shut down Unit 1 is demonstrated. However, Criteria 5 would not be met for Unit 2, and the capability to safety shut down that Unit cannot be demonstrated.
Compensatory actions and long term resohitions:
The capability to safely shut down Unit I following a fire in this zone that results in loss of ventilation in the MCR and AEER is established by the bounding evaluations for fire in.these rooms. Therefore, no compensatory actions nor long term fixes are required.
The capability to safely shutdown Unit 2 following a fire in zone 11.4-0 that results in the loss of ventilation in the MCR and Aux Electric Equipment Room, and loss of power to the Fire Hazards Panel will be assured by the following interim compensatory actions, and long term resolutions.
The following interim compensatory actions have been instituted to ensure that a fire severe enough to 4
threaten safe shutdown equipment from both divisions will not occur, and to ensure that the capability to restore safe shutdown functions is available even if such a fire did occur:
- 1. In the event that the dctcction system is disabled, a continuous fire watch will be established.
- 2. Temporary procedures and a temporary alteration are being prepared and materials ordered to allow restoration of one train of the control room ventilation system in a once through purge j
mode using 100% outside air. These procedures involve opening two dampers in the supply air flowpath, and manually operating a supply fan at the switchgear bus breaker, and opening control room envelope doors to establish a relief flowpath to the turbine building operating deck.
it is estimated that &csc actions can be implemented within 30 minutes of receiving a control 5'
l l
room ventilation airflow alarm. These actions will restore adequate air flow through the control room envelope using outside air. The temporary alteration will be installed no later than 6/21/96.
- 3. Training will be prosided for all scheduled shifts prior to assuming their shift responsibilities.
All training of scheduled shifts will occur within one week of the installation of the measures discussed in #2 above.
- 4. The common area surrounding the cables of concern (redundant VC cables, cables powering Unit 2 Fire Hazards Panel) has been designated a transient combustible exclusion area with no hot work allowed. If transient combustibles are brought in the arca or hot work is performed, a continuous fire watch in the zone will be established.
The following long term actions will be implemented as a long term solution to this problem:
- 1. A Thermo-lag resolution cable re-route modification being installed in the upcoming Unit 2 refuel outage (B2R06) in September,1996, will restore this zonc to compliance with Appendix R. Upon completion of this modification, the interim compensatory measures will be discontinued.
- 2. Also, to insure consistency with Braidwood Unit 2, a modification will be installed to provide an alternate power source for the Unit 2 Fire llazards Panel by the Unit 2 refueling outage B2R07.
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FIRE ZONE 11.4C-0 RADWASTE AND REMOTE SIIUTDOWN CONTROLS ROOM:
Qqsgr.iption of firglgng; i
Fire Zone 11.4C 0 is located on Auxiliary Building Elevation 383 and includes the radwaste and the Unit I and 2 remote shutdown control rooms located between row / columns L and P and 23 and 28 as shown on Figure 2.3-13 of the Fire Protection Report (FPR). The fire zone is located in the Unit 2 area of the Aux Duilding. This zone is normally occupied by an operator who is present at the radwaste control panel.
The zone contains ionization detectors which annunciate and alarm in the Main Control Room (MCR).
No automatic suppression systems are present.
thi ting safgjhutdown analysis discussion:
f FPR Sections 2.4 2.46 (Unit 1) and 2.4.2.45 (Unit 2) discuss the safe shutdown analysis for this zone.
Control cables for redundant safe shutdown equipment are routed through this zone. Instrument cables required to verify safe shutdown are also present in the zone. The existing analysis states a fire in this zone will render inoperable controls on the remote shutdown panel and the corresponding controls in the MCR, however, alternate shutdown capability is provided for all controls located on the panel. The existing analysis states that instrumentation located on the remote shutdown panel is isolated from instrumentation at the MCR. It is stated that all instrumentation lost at the remote shutdown panel has either redundant channels of the same instrument or diverse instruments of equivalent information in the MCR or elsewhere.
FPR resisions required to address current Control Room Ventilation (VC) system evaluations:
FPR Section 2.4.2.46 (Unit 1) currently does not list the routing of redundant VC safe shutdown cables brought to the Unit I remote shutdown panelin zone 11.4C-0. The Unit 2 remote shutdown panel does not contain any VC controls or instrumentation. Unit I does not discuss the potential loss of both trains of the VC system due to a fire in this zone. In this zone, new cvaluations indicate that both VC Return Fans OA and OB would be disabled, along with redundant dampers such as both VC Supply Fan discharge dampers (OVC033Y, OVC172Y). When these recently identified additional VC safe shutdown cdmponents and cables are added to the analysis, both trains of VC become vulnerable to a fire in this zone. The redundant safe shutdown VC cables are routed in trays / conduits which enter the Unit I remote shutdown panel from the ceiling and floor separated by a metal barrier between train panels. If the modification discussed below under compensatory actions and long term resolution is installed, loss of redundant VC trains is not possible and no FPR resisions will be required. If the modification is not installed, the conclusion that both trains of VC are vulnerable to a fire in this zone will be added to the safe shutdown analyses for Unit 1. Also the alternate safe shutdown capability discussed in Section 2.4.2.46 will be resised to take credit for the fire hazards panel instead of the MCR instrumentation. The resised alternate safe shutdown capability is discussed below.
1 Alterr1te safe shutdown capability with the loss of the entire VC system:
Existing safe shutdown analyses for fires in the MCR and the Aux Electric Equipment Rooms bound the consequences of the loss of ventilation in these rooms. FPR Unit 1 Sections 2.4.2.4 & 2.4.2.21 and Unit 2 Sections 2.4.2.2 & 2.4.2.20 currently evaluate the capability to achieve and maintain safe shutdown following a fire occurring in the Main Control Room Fire Zone 2.1-0 and the Aux Electric Equipment Rooms (fire zones 5.5-l&2). The fire in the MCR is assumed to disable control and instrumentation functions and force the evacuation of the MCR. The fire in the Aux Electric Equipment Rooms are assumed to disable redundant centrol and instrumentation functions. These existing evaluations for fire bound the consequcoces of the loss of ventilation to the MCR and the Aux Electric Equipment Rooms.
The existing criteria for achieving safe shutdown following a fire in these zones arc.
7
1.
Reactor is tripped and control rods inserted is verified prior to evacuation.
1 Pressurizer safety valves provide over-pressure protection for hot standby and the PORV controls can be repaired and restored for later controlled depressurization. PORV block valves can be operated from their respective MCCs.
3.
Main Steam Relief valves will be operated locally using the hand hydraulic pumps.
4.
Control of essential hot shutdown equipment can be achieve at the Remote Shutdown Panel and locally using BOA PRI-5 " Control Room Inaccessibility"and BOA ELECT-5 " Local Emergency Control of Safe Shutdown Equipment" 5.
Essential instrumentation indication is available at the Remote Shutdown and/or Fire llazards Panels.
6.
Controls for RH can be repaired to achieve cold shutdown within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
Safe shutdown in fire zone 11.4C-0, if the lon of all VC should occur, will be demonstrated by applying the above criteria with the following verifications:
1.
Reactor is tripped and control rods inserted; the consequences of the loss of VC does not occur so fast that this verification cannot be made for a fire in this zone.
2.
Pressurizer safety valve function and capability to repair / operate the pressurizer PORVs or its block valves are not impaired as a result of a fire in this zone.
3.
Local manual operation of the main itcam relief valves using the hand hydraulic pumps is not impaired as a result of a fire in this zone.
4.
Operation of the essential hot shutdown equipment utilizing BOA PRI-5 and BOA ELECT-5 is not impaired as a result of a fire in this zone.
5.
Essential instrumentation on the Unit 1&2 Fire llazard Panels are available for a fire in this zone.
i 6.
Capability to repair / operate equipment necessary for residual heat removal is not impaired as a result of a fire in this zone.
l Cgmoensatory actionsand lone term resolutigns:
The following interim compensatory actions are being instituted to ensure that the capability to restore safe shutdown functions are available even if a fire should occur.
]
- 1. There is currently a set of equipment for local safe shutdown actions in the remote shutdown control room. One additional set of equipment for local safe shutdown actions will be provided in the Shift Engineers OfTice by 6/21/96.
- 2. Operating procedure BOA PRI-5
- Control Room inaccessibility," has been reviewed for use at the Fire llazards Panel under the conditions postulated as a result of a fire at the Unit I remote shutdown panel.
No fundamental changes to the procedure were identified. As an enhancement to BOA PRI-5, compensatory measurc #3 below will be implemented to provide a means to make the MCR habitable and to have MCR instrumentation available.
- 3. Temporary procedures and a temporary alteration are being prepared and materials ordered to allow restoration of one train of the control room ventilation system in a once through purge mode using 100%
outside air, opening two dampers in the supply air flowpath, and mamially operating a supply fan at the switchgear bus breaker, and opening control room envelope doors to establish a relief floupath to the turbine building operating deck. It is estimated that these actions can be implemented within 30 minutes of receiving a control room ventilation airflow alarm. These actions will restore adequate air flow using outside air through the control room emW The temporary alteration will be installed at Byron by no later than 6/21/96.
8
. - - -.- -....=. ~...........
_.. ~. -
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- 4. Training will be presided for all scheduled shifts prior to assuming their shift responsibilities. All training of schululed shifts will occur within one week of the installation of the measures discussed in #3 above.
For fire zone 11.4C-0, the long term corrective actions have not been determined at this time, and are still being evaluated. Actions being considered include a plant modification to remove one train (as a minimum) of VC from the remote shutdown panels. Details of this long term action will be prosided in the LER associated with this issue.
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o FIRE ZONE 11.5 0. AUXILIARY BUILDING ELEVATION 401 FEET:
12pstiption of fire zonq; Fire Zone 11.5-0 is located on Auxiliary Building Elevation 401 and includes all of the general open-access areas between row / columns L and W and 10 and 26 as shown on Figure 2.3-12 of the Fire Protection Iaport (FPR). The fire zone includes both Unit I and Unit 2 areas of the Aux Building. This zone secs normal foot traflic by site personnel performing activities in the Auxiliary Building. The zone contains ionization detectors which annunciate and alarm in the Main Control Room (MCR). No automatic suppression systems are present except for automatic sprinklers provided around a stairway at coordinates P-18 and over the waste oil tank at coordinates M-11.
Existing _gfg shutdown analysis discussion:
FPR Sections 2.4.2.47 (Unit 1) and Section 2.4.2.48 (Unit 2) discuss the safe shutdown analysis for this zone. Power and/or control cables for redundant safe shutdown equipment are routed through this zone.
Instrument cables regnired to verify safe shutdown are also present in the zone. The existing analysis states Division i1 (Unit 1) and Division 22 (Unit 2) cables will be protected as necessary with fire rated barricts. The existing analysis takes credit for the Fire llazards Panel for selected instrumentation. The existing analysis is currently being revised to reflect re-routing of cables out of the zone to accomplish equivalent protection previously provided by the Thermo-Lag fire barricts.
FPR revisions reauired to addrgss current Control Room Ventilation fVC) system evaluations:
FPR Section 2.4.2.48 (Unit 2) currently lists the routing of some redundant VC safe shutdown cabics in zone 11.5 0 and concludes the Division i1 VC train will be available, operated locally. Unit I does not list VC cables. In this zone, new cvaluations indicate that both VC Return Fans O A and OB would be disabled, along with redundant dampers such as both VC Supply Fan discharge dampers (OVC033Y, 0VC172Y). When these recently identified additional VC safe shutdown components and cables are added to the analysis, both trains of VC become vulnerable to a fire in this 7one. The redundant safe shutdown VC cabics are routed in trays / conduits which are separated by a distance of approximately 10 fect. This occurs at a single point of closest approach near column rows 15 and Q. The conclusion that both trains of VC are vulacrable to a fire in this zone will be added to the safe shutdown analyses for this zone. The existing conclusion that Division 11 VC train can be operated locally will be removed Also the alternate safe shutdown capability discussed below will be added to the FPR sections.
Alternate safgjhutdcwn capability with the loss of the entire VC system:
Existing safe shutdown analyscs for fires in the MCR and the Aux Electric Equipment Rooms bound the consequences of the loss of ventilation in these rooms. FPR Unit i Sections 2.4.2.4 & 2.4.2.21 and Unit 2 Sections 2.4.2.2 & 2.4.2.20 currently evaluate the capability to achieve and maintain safe shutdown following a fire occurring in the Main Control Room Fire Zone 2.1-0 and the Aux Electric Equipment Rooms (fire zones 5.5-l&2). The fire in the MCR is assumed to disable control and instrumentation functions and force the evacuation of the MCR. The fire in the Aux Electric Equipment Rooms are assumed to disabic redundant control and instrumentation functions. These existing evaluations for fire bound the consequences of the loss of ventilation to the MCR and the Aux Electric Equipment Rooms.
Ilowever, these evaluations assume that instrumentation provided at the Fire Hazards Panels,1/2PL10J, is available. For a fire in this zone, Unit 1 Fire Hazard Panel will be powcred from Division 12 as a result of a Thermo-Lag resolution cable re-route modification installed in May 1996. For Unit 2, Division 22 is the protected division, and it remains availabic. Division 22 cables are protected with Thermo-Lag fire barrier. An hourly fire watch is in place. Modifications to climinate Thermo-Lag are designed and will be installed by 12/96.
i 10
. The existing criteria for achieving safe shutdown following a fire in these zones are:
1.
Reactor is tripped and control rods inserted is verified prior to evacuation.
2.
Pressurizer safety valves proside over pressure protection for hot standby and the PORV controls can be repaired and restored for hter controlled depressurization. PORV block valves can be operated from their respective MCCs.
3.
Main Steam Relief valves will be operated locally using the hand hydraulic pumps.
4.
Control of essential hot shutdown equipment can be achieve at the Remote Shutdown Panel and locally using BOA PRI 5 " Control Room Inaccessibility"and BOA ELECT-5 " Local Emergency Control of Safe Shutdown Equipment" 5.
Essential instrumentation indication is available at the Remote Shutdown and/or Fire llazards Panels.
6.
Controls for Ril can be repaired to achieve cold shutdown within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
Safe shutdown in fire zone i1.5-0, if the loss of all VC should occur, will be demonstrated by applying the above criteria with the following verifications:
1.
Reactor is tripped and control rods inserted, the consequences of the loss of VC does not occur so fast that this verification cannot be made for a fire in this zone.
2.
Pressurizer safety valve function and capability to repair / operate the pressurizer PORVs or its block valves are not impaired as a result of a fire in this zone.
3.
Local manual operation of the main steam relief valves using the hand hydraulic pumps is not impaired as a result of a fire in this zone.
4.
Operation of the essential hot shutdown equipment utilizing BOA PRI-5 and BOA ELECT-5 is not impaired as a result of a fire in this zone.
5.
Essential instrumentation on the Unit 2 Fire llazard Panel is available for a fire in this zone.
For Unit 1, the Division 12 power supply for the Fire llazard Panel is available since the installation of Thermo-Lag resolution cable re-route modifications in May 1996.
6.
Capability to repair / operate equipment necessary for residual heat removal is not impaired as a result of a fire in this zone.
Compensatory actions and lone term resdutions:
The capability to safely shutdown following a fire in zone 11.5-0 that results in the loss of ventilation in the MCR and Aux Electric Equipment Room is established by the bounding evaluations for fire in thesc rooms. Therefore, no compensatory actions or long term fixes are required other than currently ongoing modifications to resolve the Thermo-Lag fire barrier (GL 92-08) issue.
t 1
4 E
t I
11 I
c a i
.i. -
.m.-
.mm.
m_
l FIRE ZONE 11.6-0. AUXILIARY BUILDING ELEVATION 426 FEET:
Qggt ption of fire zone:
i Fire Zonc 1 L6-0 is located on Auxiliary Building Elevation 426 and includes all of the general open-access areas between row / columns L and V and 11 and 26 as shown on Figure 2.3-10 of the Fire Protection Report (FPR). The fire zone includes both Unit I and Unit 2 areas of the Aux Building. This zone secs normal foot traflic by site persennel performing activitics in the Auxiliary Building. The zone contains ionization detectors which annunciate and alarm in the Main Control Room (MCR). No automatic suppression systems are present except for automatic sprinklers prosided around a stairway at coordinates P-18.
Thigline safg_ghtttdown analysis discussion:
FPR Sections 2.4.2.51 (Unit 1) and 2.4.2.52 (Unit 2) discuss the safe shutdown analysis for this zone.
Power and/or control cables for redundant safe shutdown equipment are routed through this zone.
Instiument cables required to verify safe shutdown are also present in the zone. The existing analysis states Division 12 (Unit 1) and Division 22 (Unit 2) cables will be protected as necessary with fire rated barriers. The existing analysis takes credit for the Fire llazards Panel for selected instrumentation. The existing analysis is currently being resised to reficct re-routing of cables out of the zonc to accomplish equivalent protection previously provided by the Thermo-Lag fire barriers.
FPR revisions reauitgd to address current Control Room Ventilation (VC) system evaluations:
FPR Section 2.4.2.52 (Unit 2) currently lists the routing of some redundant VC safe shutdown cables in zonc 11.6-0 and concludes the Division 12 VC train will be available, operated locally. Unit I does not list VC cables. In this zone, new cvaluations indicate that both VC Return Fans OA and OB would be disabled, along with redundant dampers such as both VC Supply Fan discharge dampers (0VC033Y, OVC172Y). When these recently identified additional VC safe shutdown components and cabics are added to the analysis, both trains of VC become vulnerable to a fire in fhis zone. The redundant safe shutdown VC cables are routed in trays / conduits which are separated by a maximum distance of approximately 10 feet. This occurs at a single point of closest approach near column rows 16 and P. The conclusion that both trains of VC are vulnerable to a fire in this zone will be added to the safe shutdown analyses for this zone. The existing conclusion that Division 12 VC train can be operated locally will be removed A1.;o the alternate safe shutdown capability discussed below will be added to the FPR sections.
Alternate safe shutdown capability with the loss of the entire VC system:
Existing safe shutdown analyscs for fires in the MCR and the Aux Electric Equipment Rooms bound the consequences of the loss of ventilation in these rooms. FPR Unit 1 Sections 2.4.2.4 & 2.4.2.21 and Unit 2 Sections 2.4.2.2 & 2.4.2.20 currently evaluate the capability to achicyc and maintain safe shutdown following a fire occurring in the Main Control Room Fire Zone 2.1-0 and the Aux Electric Equipment Rooms (fire zones 5.5-l&2). The fire in the MCR is assumed to disable control and instrumentation j
functions and force the evacuation of the MCR. The fire in the Aux Electric Equipment Rooms arc assumed to disable redundant control and instrumentation functions. These existing evaluations for fire bound the consequences of the loss of ventilation to the MCR and the Aux Electric Equipment Rooms.
The Fire llazard Pancis remain available for a fire in this zone because Divisions 12 and 22 are protected t
l divisions. Division 22 is protected with Thermo-lag. An hourly fire watch is in place. Modifications to climinate Thermo-Lag are designed and will be installed by 12/96.
The existing criteria for achieving safe shutdown following a fire in these zones are:
4 1.
Reactor is tripped and control rods inserted is verified prior to evacuatioi 3
12 l
I.
5 i.-
2.
Pressurizer safety valves provide over-pressure protection for hot standby and the PORV j
controls can be repaired and restored for later controlled depressurization. PORV block i
valves can be operated from their respective MCCs.
j j
3.
Main Steam Relief valves will be operated locally using the hand hydraulic pumps.
4.
Control of essential hot shutdown equipment can be achieve at the Remote Shutdown Panel
{
and locally using BOA PRI-5. " Control Room Inaccessibility"and BOA ELECT-5 " Local Emergency Control of Safe Shutdown Equipment".
i -
5.
Essential instrumentation indication is available at the Remote Shutdown and/or Fire IIazards Panels.
6.
Controls for RH can be repaired to achieve cold shutdown within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
l
)
Safe shutdown in fire zone 11.6-0, if the loss of all VC should occur, will be demonstrated by applying the L
above criteria with the following verifications:
I l
1.
Reactor is tripped and control rods inserted; the consequences of the loss of VC does not occur so fast that this verification cannot be made for a fire in this zone.
l 2.
Pressurizer safety valve function and capability to repair / operate the pressurizer PORVs or 1
its block valves are not impaired as a result of a fire in this zone.
l l
3.
Local manual operation of the main steam relief valves using the hand hydraulic pumps is not impaired as a result of a fire in this zone.
l 4.
Operation of the essential hot shutdown equipment utilizing BOA PRI-5 and BOA ELECT-5 is not impaired as a result of a fire in this zone.
5.
Essential instrumentation on the Unit 1&2 Fire llazard Pancis are available for a fire in this i
zone.
l 6.
Capability to repair / operate equipment necessary for residual heat removal is not impaired as 1
a result of a fire in this zone.
)
{.
Compensatory actions and long term resolutions:
J The capability to safely shutdown following a fire in zonc 11.6-0 that results in the loss of ventilation in the MCR and Aux Electric Equipment Room is established by the bounding evaluations for fire in these j
rooms. Therefore, no compensatory actions or long term fixes are required other than currently ongoing modifications to resolve the Thermo-Lag fire barrier (GL 92-08) issue.
i 4
l-i 13
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