IR 05000454/1997019

Insp Repts 50-454/97-19 & 50-455/97-19 on 970908-18. Violations Noted & Being Considered for Escalated Enforcement Action.Major Areas Inspected:Several post-fire Safe Shutdown Issues

ML20199H637
Person / Time
Site:	Byron
Issue date:	10/02/1997
From:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
Shared Package
ML20199H594	List: IR 05000454/1997019 ML20199H590
References
50-454-97-19, 50-455-97-19, NUDOCS 9711260177
Download: ML20199H637 (14)

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U,' S. NUCLEAR REGULATORY COMMISSION

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Docket Nos: 50-454; 50-455' ,.

License Nos: - NPF-37; NPF-66 -

Report Nos: 50-454/97019(DRS); 50-455/97019(DRS)

h Licensee: Commonwealth Edison Company Facility: Byron Nuclear Power Station, Units 1 & 2 Location: 4450 North German Church Road Byron, IL 61010 Dates: September 8-18, 1997 Inspector: D. Chyu, Reactor Engineer Approved by: Ronald Gardner, Chief Engineering Specialists Branch 2 Division of Reactor Safety

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EXECUTIVE SUMMARY Byron Nuclear Station Units 1 and 2 NRC Inspection Report 50-454/97019(DRS); 50-457/97019(DRS).

This regional inspection reviewed seveial post-fire safe shutdown issues. The following strengths and weaknesses were identified:

Plant Support

• The licensee identified, during Thermo-Lag resolution activities, that several incorrect cable separation assumptions could poten~ ally result in the inability to achieve and rnaintain safe shutdown conditions if a postulated fire occurred in certain fire zone This is an apparent violation (Section F2.1). All necessary modifications were completed. The long-term corrective actions were adequate and comprehensiv l l

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Report Details IV. Plant Support F2 Status of Fire Protection Facilities and Equipment F2.1 Anoendix R lssues Inspection Scope The licensee identified several post-fire safe shutdown deficiencies as part of an effort to evaluate Thermo-Lag installations throughout the plant in response to Generic Letter 92-08. In October 1995, Braidwood personnel identified the potential loss of both trains of miscellaneous electric equipment rooms (MEERs) supply fan Byron personnel also identified two similar problems in Fire Zones 11.6-0 and 11.4-O. In June 1996, several deficiencies were identified regarding assumptions maoe in the Byron Fire Protsetion Report cc.'ceming the control room ventilation (VC)

system. In November 1996, the iicensee identified that a fire in Fire Zones 3.2A-1 and 3.2A 2 could cause damage to redundant engineered safety feature (ESP)

buse The inspectors reviewed LER 50-454/95005, Supplement 2; licensee letter, " Actions Taken in Response to Fire Protection Report Safe Shutdown Analysis Deficiencies,"

dated November 20,1996; and selective portions of the Byron Fire Protection Repor The licensee completed the verification of all cable routings and components associated with the SSA with no additional deficiencies. An ef,' ort to re-verify the entire safe shutdown analysis (SSA) was expecteo to be completed by the end of 1997. A data base was also developed in which information concerning the cables routings and equipment required for safe shutdown was stored. Based on this information, a fault tree was being developed to better assess safe shutdown capability. A revision to the SSA would be issued in 199 Observation and Findinas Fire Zone 11.6-0. Auxiliary Buildina Elevation 426 On October 10,1995, the licensee identified that a fire in Fire Zone 11.6-0 could render inoperable the Divisions 12 and 22 MEER supply fans. This was contrary to the assumptions made in the Byron Fire Protection Report (FPR), Sections 2.4.2.51 and AS.8.22. Fire Zone 11.6-0 contained motor control centers (MCCs) 132XS and 232X5, which shared common source breakers with MrR supply fans. A fire in the zone could render MEER supply fans unavailable de 'pening of the source breakers. This issue was discussed in inspection Repon 50-454/455-9501 In addition, control cables associated with the system auxiliary transformer

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were routed through the zone. A fire in this zone would cause the loss of offsite power. After reaching the temperature limit for equipment located in

' the MEER, the diesel generators (DGs) would be rendered inoperable'due to the loss of DC control power. Without-offsite and onsite emergency power, safe shutdown conditions could not be achieved and maintained, in June 1996 and November 1996, the licensee had installed additional MEER

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breakers on Units 1 and 2, respectivel On October 26,1995, the licensee determined that a fire in this zone could render both Unit 1 auxiliary feedwater (AF) pumps inoperable because two control cables (IAF338 and 1AF346) associated with the 1B AF pump were not protected with a 3-hour rated fire barrier (the 1A AF pump was assumed to.be damaged by the fire). These affected cables were associated with the 1B AF pump low suction pressure trip. If these cables were damaged,- the 1B AF pump could not be started. Since the offsite power would not be available to the main feed water pumps,-the station had to rely on feed- and-bleed operation, which required DC control power, to achieve safe shutdown conditions. The DC power would not be available due to MEER heatu Therefore, safe shutdown conditions could not be achieved and maintained due to the inability to feed-and-bleed the reactor coolant system. In June 1996, a new switch that would bypass the trip function associated with the

affected AF control cables was installed.

l Fire Zone 11.4-0. Geners! Area of Auxiliary Buildino. Elevation 383 On October 13,1995, the licensee identified that a fire in Zone 11.4-0 could render the 1A DG and the Division 11 ESF switchgear room supply fan inoperable. This was contrary to the assumptions ma.3 in FPR Sections 2.4.2.43 and A5.8.17. Fire Zone 11.4-0 contained the power cables for the diesel oil transfer pump and MCC 131X3. Motor control center 131X3 shared i the same source breaker with the redundant diesel oil transfer pump and the j Division 11 ESF switchgear room supply fan. A fire in this zone could cause the opening of the source breaker and damage to the power cabl Therefore, the 1A DG and the Division 11 ESF switchgear room supply fan would not be available. This issue was discussed in Inspecilon Report 50-454/455-95011 and a Severity Level IV violation was issued.

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Subsequently, the licensee indicated that the Unit 1 fire hazard panel (FHP)

would not be available because it received power from Division 12, the unprotected division in this fire zone. Offsite power would be available until the ESF switchgear was no longer available due to room heatup caused by l the failed supply fan. The effect of a fire in Fire Zone 11.4-0 for Unit 1 would be the loss of DGs, offsite power, VC system (discussed in the paragraph below),-and the FHP. Safe shutdown conditions could not be achieved and

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l maintained upon loss of the equipment mentioned above. In May 1996, the licensee rerouted cables associated with Division 12 DG out of Fire Zone 11.4-0 to ensure the availability of power to the Unit 1 FHP and installed an additional breaker so that MCCs 131X3 and 131X5 did not share the same supply breaker, in August 1997, the Division 11 power supply capability to the Unit 1 FHP was added; therefore, the operators could select the preferred power source for the FH On June 4,1996, the licensee identified that a fire in Zone 11.4-0 could render the VC system inoperable, in the original SSA, several VC system dampers were not identified as equipment required to achieve safe shutdown conditions. However, the licensee determined that the dampers would fail closed and block the system flow path. Therefore, a fire in this zone would disable the VC system. This would result in a heatup of the main control room (MCR) and the auxiliary electric equipment room (AEER) which would render electrical components in these rooms inoperable. There was an existing procedure BOP-VC-15, Revision 0, which provided alternate methods of cooling the AEER in the event both VC trains were inoperable. The inspectors considered 'his procedure to be insufficient to control MCR and AEER heatup because the procedure did not require opening the damper Upon reaching the equipment temperature limit in the MCR and AEER due to the loss of VC system, the instrumentation required to safely shut down Unit 2 would be lost at the main control room and remote shutdown panel. A fire in Fire Zone 11.4-0 would also disrupt power to the Unit 2 FHP. Therefore, safe shutdown conditions could not be achieved and maintained on Unit 2 if a fire occurred in Fire Zone 11.4-0. In November 1996, cables associated with the Division 22 DG were rerouted out of Fire Zone 11.4-0 to ensure the availability of power to the Unit 2 FHP. The licensee was in the process of adding Division 21 power supply to the Unit 2 FHP (estimated to be completed by the end of September 1997).

Fire Zones 3.2A-1 and 3.2A-2. Non-Searecated Bus Duct Areas On October 26,1905, the licensed identified that two control cab;es (1DG157 and 1DG175) for the 1A DG were not protected with a 1-hour rated fire barrier in Fire Zone 3.2A-1. In. addition, the Unit 1 bus duct and the cross-tie cables from Unit 2 were also routed through the same zone and could be damage C n November 7,1996, the licensee identified that a fire in Fire Zone 3.2A-1 or 3.2A-2 cou!d render redundant 4 Kv ESF buses and DGs inoperable. The following sequence of events woald have to occur to render this equipment inoperable:

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A loss of off-site power occurred and DGs were powering the ESF buses,

A loss of DC control power to ESF breakers and DG output breakers,

- A fault occurred on the 4 Kv power cable from Bus 141/241 to essential service water (SX) Tower unit substation 131Zl231 In Fire Zone 3.2A-1, Division 11 was considered protected and Div:sion 12 unprotected. This zone contained Division 11 normal and reserve DC control power cables, and a 4 Kv power cable from Bus 141 Cubic!e 5 to essential service water tower unit substation 1312. A fire could cause the loss of DC control power to Buses 141 and 142. This would prevent bus breakers from opening to isolate cable fault currents. The fire could subsequently cause a fault on the 4Kv power cables associated with the ESF buses. The fault current would not be interrupted because the breakers would not have control power to open and damage could occur to the ESF buses and the DGs if they were powesing the ESF buses. Fire Protection Report Section 2.4. addressed the loss of DC power and the resultant loss of ability to close breakers remotely. However, it did not address the loss of DC control power preventing Bus 141 from opening to isolate cable fault Before 1994, cables associated with the VC system were routed through this area and could be damaged by a fire. The Unit 1 FHP would not be available because it was powered by Division 12, the unprotected division in this zon Based on the above, safe shutdown conditions could not be achieved and maintained for a postulated fire in Fire Zone 3.2A-1. After 1994, the affected VC cables were protected by Darmatt. In May 1997, Darmatt was installed on the 4 Kv power cable from Bus 141 to SX tower unit substation 131Z to prevent a fire-induced fault affecting Bus 141 and the 1A DG, The licensee recently approved a modification to reroute one train of a divis!on of DC cables out of this zone. The inspector considered the corrective actions taken to date to be adequate because the operators could use Byron Abnormal Operating Procedure ELEC-5, " Local Emergency Control of Safe S/D Equipment," to manually manipulate breakers upon a loss of DC powe Fire Zone 3.2A-2 contained Division 21 normal and reserve DC control power cables and 4 Kv power cable from Bus 241 to SX tower unit substation 231 The recult of a fire was similar to that for Fire Zone 3.2A-1; safe shutdown conditions could not be achieved and maintained if a postulated fire occurred in Fire Zone 3.2A-2. In May 1997, the licensee installed Darmatt on the 4 Kv power cab!c from Bus 241 to SX tower unit substation 231Z to prevent a fire-induced fault affecting Bus 241 and the 2A D Loss of 1B Centrifuaal Charaina Pump in Fire Zone 11.3-1

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On October 26,1995, the licensee identified that a fire in Fire Zone 11.3-1 could render both Unit 1 charging pumps inoperable because the power cable for _the 1B charging pump was not protected with a 1-hour rated fire barrier.-

This assumption was contrary to FHP Section 2.3.2.38. According to the safe shutdown analysis, the 1B charging pureo was to be used with other equipment to assure safe shutdown._ Ho wer, with the loss of both Unit 1 ;

charging pumps, safe shutdown conditions could not be cchieved and maintained if a fire occurred in Fire Zone 11.3-1. In June 1996, the licensee revised the protected division in Fire Zone 11.3-1 from Division 12 to 11 and rerouted the cable for the 1A chargin0 pump out of thic zon Loss of 1RH8701A in Fire Zone 11.5-0-

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_ On October 26,1995,' the licensee identified that a fire in Fire Zone 11.5-0 could render motor operated vaives (MOVs) 1RH8701A and 1RH87018 inoperable because a control cable (1RH030) for MOV 1RH8701A was not protected with a 3-hour rated fire barrier. This was contrary to the assumption made in FPR Sections 2.4.2.47 and 2.4.3.2.1.3. These two MOVs were considered the isolation for the high to-low pressure boundary between the reactor coolant system and residual heat removal system.

.: These valves were normally open in Mode 4 for shutdown cooling and closed in Modes 1,2, and 3c However, a fire in Fire Zone 11.5-0 could induce multiple hot shorts and cause these two MOVs to spuriously open. The result of this fire was an inter-system loss'of coolant accident. Safe shutdown conditions could not be achieved and maintained if multiple hot shorts occurred due to a fire in this zone. In May 1996, the licensee revised i

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Byron General Procedure 1001T3 to close MOV RH 3701B and de-energize the breaker in Modes 1,2, and In addition, a fire in this zone would cause the VC system to be inoperabl The effect of losing the VC system was identical to that of Fire Zone 11.4- The initial SSA did not recognize that VC system dampers would fail closed and block system flow. In addition, the Unit 1 FHP would not be available because it received power from Division 12 that was unprotected in this zon Upon reaching the temperature limit in the MCR and AEER, the instrumentation required to shut down Unit 1 would b'e lost at the MCR and lemote shutdown panel. Without the Unit 1 FHP, the licensee could not ochieve and maintain safe shutdown conditions. In May 1996, the affected Division 12 cables were rerouted out of the zon Loss of VC system and Unit 1 FHP in Fire Zone 3.2B-1 On June 4,1996, the licensee identified that a fire in Fire Zone 3.28-1 would render the VC system inoperable because the VC dampers would fail closed and block system flow path. Upon reaching the temperature limits in the MCR and AEER, instrumentation required to safely shut down Unit 1 would be lost.at the MCR and remote shutdown panel. Before May 1996, cables associated with the Division 12 ESF switchgear room fan were routed through the zone. Division 11 was considered protected and Division 12 unprotecte A fire would damage the Division 12 cables and cause the loss of the Division 12 ESF switchgear room fan. Upon reaching the temperature limit in the room, Bus 142 would not be able to supply power to the Unit 1 FH Instrumentation at the FHP would not be available. Therefore, before May 1996, the licensee could not achieve and maintain safe shutdown condition In May 1996, the affected cables were rerouted out of the zon Loss of DGs in Fire Zones 3.1-1 and 3.1-2 On October 26,1995, the licensee identified that a fire in Fire Zones 3.1-1 or 3.1-2 could render the 1A or 2A DG, respectively, inoperable, in both examples, control cables for the DGs were not protected with a 1-hour rated fire barrier, in addition, the offsite power would not be available because cables associated with the system auxiliary transformer were routed through the same zone. In both cases, the operators could use Byron Abnormal Operating Procedure ELEC 3, " Loss of 4KV ESF Bus," to cross-tie power from the opposite unit. Therefore, safe shutdown conditions could be achieved and maintained if a fire cacurred in Fire Zones 3.1-1 or 3.1-2. The licensee installed Darmatt on the cablas associated with 1A DG in Fire Zone 3.1-1 in September 1995, and rerouted the 2A DG cables out of Fire Zone 3.1-2 in November 199 .

Loss of 1A SX Pumo On October 26,1995, the licensee identified that a fire in Zone 11.3-0 could rerader both Unit 1 SX pumps inopeoble because the pow" cable (1SX001)

for the 1A SX pump was not protected with a 3-hour rated nre barrier. This was contrary to the assumption made in FPR Section 2.4.2.37. The cables for the 1A and 1B SX pumps were separated by 30 feet with intervening combustible materials. Upon the loss of both Unit 1 SX pumps, the licensee could use Byron Abnormal Operating Procedure PRI-7, " Essential Service Water malfunction," Attachment A to align for single pump operations and cross-tie the SX header. Therefore, safe shutdown conditions could be achieved and maintained. In May 1996 and November 1996, the licensee rerouted cables for the 1A and 2B SX pumps out of Fire Zone 11.3- Other Affected Zones Associated With VC System In addition to the above deficiencies, on June 4,1996, the licensee identified that a fire in Fire Zones 2.1-0,11.4C-0, or 11.6-0, could render the VC system inoperable. The existing FPR bounded the consequences of the loss of ventilation to the MCR and AEER assuming instrumentation at the FHPs was available. The instrumentation required to shut down ine units would be available at the FHPs. Theretore, these deficiencies would not affect the capability to achieve and maintain safety shutdown conditions. The licensee made a temporary alteration to Byron Operating Procedure VC-15, " Alternate Methods of Cooling the AEER," to operate the VC system in the purge mode, in addition, an alternata power supply to the Unit 1 FHPs was completed in August 1997. The modification to supply an alternate power supply to the Unit 2 FHP was estimated to be completed by September 199 c. Conclusion A fire in the following zones would affect the ability to achieve and maintain safe shutdown conditions:

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A fire in Fire Zone 11.6-0 would render inoperable the Division 12 MEER supply fan (resulting in the loss of DC power and DGs), offsite po.ver, both AF pumps, and VC system for Unit 1. In addition, a fire in this zone would render inoperable the Division 22 MEER supply fan (resulting in the loss of DC power and DGs), offsite power, and VC system for Unit A fire in Fire Zone 11.4-0 would render inoperable the DGs, Division 11 ESF switchgear room fan (resulting in the loss of offsite power), VC system, and FHP for Unit 1 and render inoperable the VC system and

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FHP for Unit A fire in Fire Zone 3.2A-1 would render inoperable the DC powe (resulting in the loss of redundant ESF buses and DGs), offsite power, and cross-tie capability from Unit 2 for Unit A fire in Fire Zone 3.2A-2 would render inoperab!c the DC power- '

(resulting in the len of redundant ESF buses and DGs), offsite power, and cross-tie capability from Unit i for Unit A fire in Fire Zone 11.3-1 would render inoperable both charging pumps for Unit A fire in Fire Zone 11.5-0 would render inoperable MOVs 1RH8701A and RH87018, VC system and FHP for Unit A fire in Fire Zone 3.2B-1 would render inoperable the VC system and FHP for Unit CFR 50, Appendix R, Section Ill.G requires, in part, that one train of systems necessary to achieve and maintain hot shutdown conditions from either the control room or emergency control station (s) is free of fire damag Section Ill.G.2 requires that, except as provided in Section Ill.G.3, where cables of equipment of redundant trains of systems necessary to achieve and maintain hot shutdown conditions are in the same fire area, separation of cables of redundant trains by a fire barrier having a 3-hour rating.or 1-hour rating with fire detector and an automatic suppression system shall be i provided. Failure to provide separation of cables of redundant trains as evidenced by the above examples is an apparent violation of 10 CFR 50, Appendix R, Section Ill.G.2 (eel 50-454/455/97019-01).

- The licensee also identified the following zones in which equipment could be damaged but would not affect the ability to achieve safe shutdown conditions.

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A fire in Fire Zone 3.1-1 would render both Unit 1 DGs inoperabl A fire in' Fire Zone 3.1-2 would render both Unit 2 DGs inoperabl A fire in Fire Zone 11.3-0 would render both Unit 1 SX pumps inoperabl A fire in Zones 2.1-0 or 11.4C-0 would render the VC system

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Failure to provide separation of cables of redundant trains in the above fire zones is a violation of 10 CFR, Appendix R, Section lil,G.2. However, this licensee-identified and corrected violation is being treated as a non-cited violation, consistent with Section Vll.B.1 of the NRC Enforcement Policy (NCV 50 454/97019-02(DRS); 50-455/97019-02(DRS)).

F8 Miscellaneous Fire Protection issues (Closed) VIO 50-454/455-95011-03: A fire in Fire Zone 11.4-0 could render Division 11 ESF switchgear room fan and 1A DG inoperable. The corrective actions were discussed in Section F2.1, The licensee identified additional items of concern in the subsequent review of the safe shutdown analysi These issues were the subject of this

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Inspection report. The inspector considered the' corrective actions taken by the licensee to be adequate. This item is close (Close) LER 50-454/95005. Revisions 0.1 and 2: Fire protection report ( discrepancies due to inadequate evaluation during preparation of original safe shutdown analysis. The items identified in the LER were discussed in inspection Report 50-459/455-95011 and were the subject of this repor The concerns identified in the LER will be tracked by eel 50-454/455-97019-01. This item is close (Close) IFl 50-454/455-95003-04: Postulated loss of solid state protection system (SSPS) during a steam line break in the turbine building. The licensee modified the SSPS cabinet fuse circuits feeding the cabinet input channels and logic cabinet power supplies from one fused 15 amps to two 10 amp circuits. The modification was completed in 1996. This item is close V. Manaaement Meetinas f X1 Exit Meeting Summary

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On September 18,1997, the inspectors presented the inspection results to licensee management. The licensee acknowledged the findings presente The inspector asked the licensee whether any material examined during the-inspection should be considered proprietary. No proprietary information was identifie )

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E PARTIAL LIST?OF! PERSONS CONTACTEDI -

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. Licensee U

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K. Kofron, Station Manager- l

Dif Brindle,- Regulatory Assurance Supervisor .

- R, Colglazier,1 NRC_ Coordinator

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G. Contrady,' Site Engineering Program Lead .

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' D. Robinson, Senior Engineer - L

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F. Pollak, Fire Protection' System Engineer D. .Wozniak,- Site Engineering Manager

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U.S.' Nuclear Reaulatory Commission

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S. Burgess, Senior Resident inspector:

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INSPECTION PROCEDURES USED-  ;

IP 64704: Fire Protection Program clP.37550: Engineering 1 IP92902: Followup - Engineering

. lTEMS OPENED, CLOSED, AND DISCUSSED t Opened .

c 50-454/455-97019-01 eel Lack of cable separation in certain fire zones

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50-454/455-97019-02- NCV . Lack of cable separation in certair 're zones LClosed L, 50-454/455-95011-03 VIO Postulated loss of Division 11 ESF switchgear room '

fan and'1A' DG in Fire Zone 11.4-0 50-454/455-95003-04 IFl - Postulated loss of solid state protection system y - during a steam line break in the Turbine Building 50-454/95005 = .LER Fire piviection discrepancies due to inadequate evaluation during preparation of

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original safe shutdown analysis i50-454/455-97019-02 NCV Lack of cable separation in certain fire zonec

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LIST OF ACRONYMS. USEDL

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TCFRi Code of Federal Regulation-

'AEER,- _

. Auxiliary Electric Equipment Room- I

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AF?  :: Auxiliary feedwater; DG- Diesel Generator -

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EEli Escalated- Enforcement item >

ESFL Engineered Safety. Feature - <

(- FHP~ Fire Hazard Panel"  !

=FPR- Fire Protection Report

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IFl; Inspection Followup Item'

.IP . Inspection Procedure -

l LER -- ~ Licensee Event Report Motor Control Center-

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1MCR Main Control Room -

1MEER' .

Miscellaneous Electric Equipment Room MOV  : Motor Operated Valve-SSA4 Safe Shutdown Analysis I SSPS: Solid _ State Protection System

, SX'- Essential Service Water

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VC= Control Room VentilationL System - >

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