ML20212F967
| ML20212F967 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 10/29/1997 |
| From: | Graesser K COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 50-454-97-19, 50-455-97-19, BYRON-97-0245, BYRON-97-245, NUDOCS 9711050184 | |
| Download: ML20212F967 (7) | |
Text
Comnmnw ealth I dmn Lumpan)'
It) ton Generatmg Station
-4150 North German Church Road It ron,11.61of tp>79 4 3
Tel 815-23 4 5 4 4 i October 29, ?997 LTR BYRON 97-?245 FILE:
1.10.0101 U.S. Nuclear Regulatory Commission Washington, DC 20555 Attention:
Document Control Desk 1
Subject:
Byron Nuclear Power Station Units 1 and 2 Response to an Apparent Violation Inspection Report No. 50-454/97019; 50-455/97019 NRC Docket Numbers 50-454, 50-455 4
Reference:
John A. Grobe letter to Mr. Graesser dated October S. 1997, transmitting NRC Inspection Report 50-454/97019; 50-455/97019 Enclosed is Commonwealth Edison Corapany's response to the Apparent Violation that was transmitted wit h the referenced letter and Inspection Report.
Ti.e Inspection Report cit ed one (1) apparent violation requiring a written response.
Comed's response is provided in the attachment.
Byron Station agrees with the consequences stated in the apparent notice 3) of violation, postulating a design basis Appendix R fire cacurring in the subject fire zones.
These consequences reflect conditions at the time of discovery, prior to consideration of corrective actions that have been
\\
implemented. At the present time, all corrective actions needed to "k restore compliance to Appendix R are complete and safe shutdown cat. be b
demonstrated for each of the discrepancies cited in the apparent va violation.
5-mo y
This letter contains the following commitments:
l.
A comprehensive review of the Fire Protection Report safe 4
g shutdown analysis is being performed to validate the technical gb integrity of the safe shutdown analysis.
bWO O 2.
A permanent design change will be implemented to remove a train of control room ventilation from the Unit 1 Remote Shutdown Panel.
This will ensure that instrumentation will be
',]((A available in the main control room, if a f, ire should occur at the remote shutdown panel in fire zone ll.4C-0.
(p:\\97byltrs\\970245. doc \\1)
A Unicom Compan)
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.s j
Byron Ltr. 97-O'.45 l
October 29, 19 '< 7 l
Page ?-
3.
At the completion of the ongoing safe shutdown analysis review, the analysis will be modeled with computer-based fault trees and data bases.
To the best of my knowledge end belief, the statements contained in this document are true and correct.
In some respects these statements are not based on my personal knowledge, but on the information furnished by other Comed employees, contractor employees, and/or consultants.
Such information has been reviewed in accordance with company practice, and I believe it to be reliable.
If your staff has any questions or comments concerning this letter, please i
refer them to Don Brindle, Regulatory Assurance Supervisor, at (815)234-5441 ext.2280.
Respectfully,
/
f, K. L. Graesser Site Vice President Byron Nuclear Pcwer Station State of Illinois SS County of Ogle Subscribed and sworn to before me this 29th Day of October 1997 7:::-_-
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KLG/DB/rp Attachment (s) cc:
A. B. Beach, NRC Regional Administrator - RIII G.
F. Dick Jr.,
Byron Project Manager - NRR Senior Resident Inspector, Byron R.
D. Lanksbury, Reactor Projects Chief - RIII F. Niziolek, Division of Engineering - IDNS (p:\\97byltrs\\970245. doc \\2)
l
,o ATTACHMENT I I
I VIOLATION (454/455-97019-01) l A fire in the following zones would affect the ability to achieve and maintain safe shutdown conditions:
A fire in Fire Zone 11.6-0 would render inoperable the Division 12 MEER supply fan (resulting in tle loss of DC power and DGs), offsite l
pover, both AF pumps, and VC system for Unit 1.
In addition, a fire in this zone would render inoperable the Division 22 MEER supply f an (resulting in the loss of DC power and DGs), of fsite power, and VC system for Unit 2.
A fire in Fire Zone 11.4-0 would render inoperable the DGs, Division 11 ESP switchgear room fan (resulting in the loss of offsite power),
VC syse.m, and FHP for Unit 1 and render inoperable the VC system and FHP for Unit 2.
A fire in Fire Zone 3.2A-1 would render inoperable the DC power
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(resulting in the loss of redundant ESF buses and DGs), offsite power, and cross-tie capability from Unit 2 for Unit 1.
A fire in Fire Zone 3.2A-2 would render inoperable the DC power (resulting in the loss of redundant ESF buses and D3s), offsite power, and cross-tie capability from Unit 1 for Unit 2.
A fire in Fire Zone 11.3-1 would render inoperable both charging
=
pumps for Unit 1.
A fire in Fire Zone 11.5-0 would render inopv.able MOVs 1RH0701A and RH8701B, VC system and FHP for Unit 1.
A fire in Fire Zone 3.2B-1 would render inoperable the VC system and FHP for Unit 1.
10 CFR 50, Appendix R, Section III.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 damage.
Section III.G.2 requires that, except as provided in Section III.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 naving a 3-hour rating or 1-hour rating with fire detector and an automatic suppression system shall bs 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 III.G.2 (EEI 50-454/455/97019-01).
(o:\\97byltrs\\910245. doc \\4)
- NASON FOR THE VIOLATION Multiple
- failures to protect'one train of systems necessary to achieve'and
. maintain safe shutdown conditions free from fire damage were reported in LER 454-95-005S2.
The. reason these multiple failures occurred can be grouped-into two - (2) z causes.-
The predominate cause was that the analysts preparing the criginal sefe shutdown analysis failed to consider or evaluate unique or subtle aspects of the_ plant
}
-design.
Design aspects not considered included: 1) multiple motor control.
centers could be powered from a single common supply breaker. 2) control dampers-can fail closed in the flowpaths of the main control room HVAC system (resulting in the loss of vital process instrumentatian), and 3) loss of DC control power; to the 4 Kv ESF.b tses can cause non-safe shutdown loads to impact safe shutdown equipment.
The second cause resulted in tnree (3) discrepancies, all which occurred on Unit 1 only.
In these_ cases, the safe shutdown analysis correctly identified the vulnerability to fire damage and the safe shutdown consequences.
However the design process failed-to incorporate the analysis results into design.
drawings and work packages.
Consequently, the necessary fire barriers were not installed on the reported electrical conduits and cable trays.
These process failures are believed to be isolated instances during the completion of
.consttaction of Unit 1.
-CORRECTIVE STEPS TAKEN AND RESULTS ACHIEVED ACTIONS TAKEN-TO ACHIEVE COMPLIANCE t
l.
Since initial construction has been completed, the mod process has been improved to include detailed program checklists.
These checklists provide guidance to the design engineer for assessing the inpact of the proposed change on the plant-design. This process improvement provides added assurance that safe shutdown considerations will be appropriately _ reviewed.
g 2.
An. action plan to assess'the FPR Safe Shutdown Analysis (Section 2.4 of the_FPR) was developed. The plan reviewed =all previously identified problems, determined root cause, and recommended corrective actions to. confirm the technical integrity of the-FPR-analysis.
3.
Daily Orders were imraediately written to identify and define to Operations the deficiencies reported =on 10/12/95, 6/04/96, and 11/07/96.
.4.-
Hourly fire watches were implemented in all fire zones impacted until permanent corrective actions were taken.
S.
There is currently a. set _of equipment for local safe-shutdown actions in the remote shutdownLeontrol room.
This equipmeat may not be accessible due to a fire in zone ll.4C-0.
Therefore,.two additional sets of appropriate equipment-for local safe shutdown actions have been provided in the Shift Manager's office.
(Applies to fire zone ll.4C-0).
(p:\\97byltrs\\970245. doc \\5)
_o
- o 6.
Fire zone 3.2B-1 was designated 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 in the zone was established.
(Applies to fire zone 3.2B-1).
The common area surrounding the cables of concern in fire zone 11.4-0 was designated a transAent combustible exclusion area with no hot work allowed.
If transient combustibles are brought into the area or hot work performed, a fire watch in the zone was established.
These administrative controls remained in ef fect until permanent resolution ot the condition was achieved.
(Applies to fire zone 11.4-0).
7.
Caution cards were placed at the appropriate locations to assure local / remote switches are kept in positions assumed in the safe shutdown evaluations. The administrative control remained in ef fect until permanent resolution of the. condition was achieved.
(Applies to fire zone 3.2B-1)
This assured the Unit 1 Fire Hazard panel was available for a fire in zone 3.2B-14 8.
Fire zones 3.2A-1 and 2 were designated transient combustible and hot work exclusion areas.
In the event that either transient combustibles must be present or hot work must be performed, a continuous fire watch in the zones was established. These administrative controls remained in effect until permanent resolution of tht condition was achieved.
9.
Temporary operating procedures were in place in the Main Control Room to provide ar. immediate r Sponse upon the receipt of an alarm on the MCR fire detection panels for a fire in zones 3.2A-1 or 2.
The procedures identified the actions to be taken to ensure the relied upon ESF 4 KV buses would be available for the safe shutdown of the unit. A description of these actions is contained in a docketed letter to the NRC dated 11/20/96.
The temporary procedures remained in effect until permanent teroJution of the condition was achieved.
10.
Plant modifications were initiated to permanently correct each deficiency described in LER 454-95-0005S2.
These included installation of Darmatt KM1 fire barrier un conduits and trays containing 1A Diesel Generator cables in the spring of 1995.
Unit 1 cable re-route modifications were installed in May 1996, and the Unit 2 re-route modifications were installed in November 1996.
11.
A permanent design change provide an alternate power source to the Unit 1 Fire Hazard ~
al from a Di,Asion 11 power source was completed and inras agust, 1997.
(Applies to fire zone 3.2B-1]
12.
A permanent design er
- e to provide an alternate power source to the Unit 2 Fire Haza canel from a Division 21 power sou.ce was completed and inst ed September, 1997.
(Applies to fire zone 11.4-0).
(p \\97byltrs\\970245. doe \\6)
- e 13.
A permanent design change to protect conduits and 4 KV power cables to the Essential Service Water (SX) Tower Unit Subs ations (131Z and 231Z) with a 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> rated fire barrier was completed and installed in fire zones 3.2A-1 and 2 by May, 1997.
14.
All modifications are installed with the exception of the VC modification to remove one train of VC from the Unit 1 Remote Shutdown Panel.
ENHANCEMENTS NOT REQUIRED TO ACHIEVE COMPLIANCE 1.
Temporary procedures and a temporary alteration have been implemented to allow restoration of one train of the control room ventilation system in a once through purge mode using 100t outside air.
These procedures involve opening two dampers in the supply rir 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 these actions can be implemented within 30 minutes of receiving a fire alarm and loss of control room ventilation.
These actions will restore adequate airflow through the control room envelope using outside air.
This temporary enhancement prevides operational flexibility to restore cooling to the Main control Room and Aux 11ary Electric Equipment Room (AEER).
This was described in a letter docketed on June 12, 1990, and was discussed with Region III and Nuclear Reactor Regulation (NRR) personnel on a July 3, 1996 conference call.
The temporary enhancement will be reinoved in BIR08 when a permanent design change is instal.1ed. (Applies to fire zones 11.4-0, 11.4C-0).
2.
Training was provided for all scheduled shifts when assuming their shift responsibilities. All training of scheduled shifts occurred within one week of the instal:ation of measures discussed in item 1 above. [ Applies to fire zones 11.4-0, 11.4C-0).
'I CORRECTIVE STEPS THAT WILL BE TAKEN TO AV07') FURTHER VIOLATION 1.
A comprehensive review of the Byron /Braidwood Fire Protection Report i
safe shutdown analysis is being performed jointly with Braidwood station.
The review is validating all the inputs and assumptions used in safe shutdown analysis.
The Design Engineering, System Engineering, and Operations Departments at Byron ha"e reviewed the selection of safe shutdown components and analysis assumptions.
The combined experience of these departments will assure the weaknesses in the previous analysis are corrected.
Similarly, these reviews are being performed at Braidwood Station, providing additional review and validation. The necessary safe shutdown analysis revisions will be prepared and incorporated into Fire Protection Report Amendment #18.
This amendment #18 will be submitted concurrent with next UFSAR update, scheduled for December 1998.
The comprehensive review is tracked by NTS Item #454-180-95-0005-03.1.
(r \\97byltrs\\970245. doc \\7)
e.
. c.'
ENHANCEMENTS NOT REQUIRED TO ACHIEVE COMPLIANCE 1.
A permanent design change to remove one train of VC from the Unit 1 Remote Shutdown Panel and fire hazard zone ll.4C-0 w:,ll be completed and installed no later than Refuel Outage BIR08.
Tnis design change is an enhancement to ensure that instrumentation will be available in the main control room, if a fire should occur at the remote shutdown pacel in fire zone ll.4C-0.
For a fire at this location, instrumsntation would be available at the Fire Hazards Panel and safe shutdown can be achieved without reliance on this design change.
This design change to enhance operational flexibility will be installed in BIR08, as previously stated in LER 454-95-005S2 and is tracked by NTS Item #454-180-95-0005S1-07.
2.
At the completion of the ongoing safe shutdown analysis review, the analysis will be modeled with computer-based fault trees and databases. This will allow design engineers the ability to evaluate proposed design changes using the safe shutdo'<n model.
The capability to achieve and.aatntain safe shutdown can be confirmed for any proposed design changes by using this model. This is tracked by NTS item #454-100-97-01901-01.
DATE WNEN TULL COMPLIANCE WILL BE AC9IEVED All actions necessary to correct the discrepancies reported in LER 454-95-005S2 and to restore compliance with the requirements of Appendix R are complete. A detailed review of the Byron /Braidwood safe shutdown analysis is ongoing and the results will be incorporated into Fire Protection Report Amendment #16.
This review will continue to search for and identify any other unknown analysis discrepancies, if they exist.
4 (pt\\97byltrs\\9702(". doc \\8)
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