ML20247R668
| ML20247R668 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 07/31/1989 |
| From: | Shelton D TOLEDO EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 1694, TAC-60994, TAC-60995, TAC-61745, NUDOCS 8908080078 | |
| Download: ML20247R668 (20) | |
Text
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. TOLEDO
%sm EDISON Docket Number 50-346 ^ C'*
- E'** C "*
License Number NPF-3 DONALD C. SHECTON Voe Presders-Nuclear Serial Number 1694 ###
July 31, 1989 United States Nuclear Regulatory Commission Document Control Desk Vash*ngton, D. C. 20555 ,
Subj ect: Fire Protection - 10CFR50, Appendix R Exemption Requests (TAC Numbers 60994, 60995 and 61745) {
Gentlemen, 4
]
Toledo Edison requested nine exemptions from the requirements of 10CFR50, Appendix R in letter dated January 12, 1987 (Serial Number 1327.). /-
Subsequently, Toledo Edison informed the Nuclear Regulatory Commission (NRC) that additional exemptions may.be necessary as.a result of the ongoing l Appendix R evaluations and, in a telephone conversation on October 5 1988, with NRC staff members, Messrs. Kubicki and Glitter, Toledo Ldfson committed to submit any additional exemption requests by July 31, 1999.
The ongoing Appendix R evaluations at Davis-Besse have identified the need for i additional exemptions presented in Attachment 1. The exemption requests ;
include: )
- 1. Two additional exemption requests involving pressurizer level !
indication circuits in the Containment and certain circuits located in ;
a manhole, and
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- 2. A revision of a previous exemption request involving conduits embedded I in concrete that was withdrawn by.Taledo. Edison in letter. dated- !
January 18, 1989 (Serial Number 1618).
The exemptions requested in Serial Number 1327 also address the lack of fixed i Y^ fire suppression in Fire Area R. This suppression-vas required since .
alternative shutdown capability in accordance with 10CFR50, Appendix R was to l
,o be provided for two systems: the Service Water System and the Auxiliary i d a. Feedvater System. In letter dated June 6, 1988 (Serial Number 1535), Toledo Edison committed to eliminate the need for a manual operator action by g replacing the governor control valves in the Auxiliary Feedvater System with solenoid-operated flow control valves that can be operated from the Control-mo Room in the event of a fire in' Fire Area R. This valve replacement has been completed and there is no longer a need for alternative shutdown capability 8o for the Auxiliary Feedvater System in Fire Area R.. However, alternative shutdown capability for the Service Vater System in Fire Area R is still g
O~ Q required and the requested exemption is necessary. g
-mat t g-THE TOLEDO EDISON COMPANY . EDISON PLAZA 300 MADISON AVENUE TOLEDO, OHIO 43652
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.I Docket Number 50-346 ,
- License Number NPF-3 Serial Number 1694 -
Page 2~
Toledo Edison has also. evaluated the Davis-Besse Appendix R exemptions previously issued by the NRC relative to the previous plant modifications and the Davis-Besse Appendix R safe shutdown analysis. Although no changes.to these previously approved exemptions are considered necessary, the ,
implementation of certain of these exemptions is discussed in Attachment 2. l i'
Toledo Edison expects Davis-Besse to be in compliance with 10CFR50, Appendix R by restart from the sixth refueling outage, contingent upon NRC approval of the previously requested exemptions and the exemptions requested herein. A^ l meeting between representatives of Toledo Edison and-the NRC is scheduled for August 1989 to discuss the requested exemptions and other issues related to the Davis-Besse fire protection program.
J If you have any questions concerning this matter, please contact l Mr. R. V. Schrauder, Nuclear Licensing Manager, at (419) 249-2366.
I Very truly yours,
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/\iQ MAL /dlm y
Attachments
.J cc: P. M. Byron, DB-1 NRC Senior Resident Inspector A. B. Davis, Regional Administrator, NRC Region III '
D. J. Kubicki, NRC/NRR Staff Reviewer T. V. Vambach, DB-1 NRC Senior Project Manager
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ATTAC3 MENT 1 APPENDIX R EXEMPTION REQUESTS 1
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~ Docket Number 50-346
- Licerse Nureber NPF-3 Serial Number 1694 Attachment 1 Page 1 Davis-Besse Nuclear Power Station EXEMPTION REQUESTS FROM 10CFR50, APPENDIX R Introduction Toledo Edison requested nine exemptions from'the requirements.of 10CFR50, Appendix R in letter dated January 12, 1987.(Serial Number 1327). As.a result of the ongoing Appendix R evaluations at Davis-Besse, Toledo Edison has' determined that two additional exemption requests are necessary and one previously submitted exemption request, later withdrawn by Toledo Edison in letter dated January 18, 1989 (Seriel' Number 1618), should be revised and re-submitted.
Toledo Edison has. determined that the exemptions requested herein conform to the applicable exemption criteria of 10CFR50.12(a). There are no prohibitions of law to preclude the activities that would be authorized by the requested exemptions, and the requested exemptions,.if granted, vould have no impact on the ecmmon defense and security. Additionally, the requested exemptions'do not present an undue risk to the public health and safety since an equivalent level of fire protection is provided as described in the discussion and evaluation sections of each requested exemption. . Special circumstances are applicable to the requested exemptions in accordance with 10CFR50.12(a)(2)(ii) in that application of the regulation for these particular circumstances is not necessary to achieve the underlying purpose of the-rule. .The alternatives proposed by the requested exemptions are justified since the application of the rcJulation represents an unwarranted burden on Toledo Edie3n resources.
The specifics of the special circumstances and ths justification of the alternative proposed by the requested exemption is discussed for each of the j requested exemptions. 1 i
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Docket Number 50-346
' License Number NPF-3 Serial Number 1694 Attachment 1 Page 2 PRESSURIZER LEVEL CIRCUITS IN THE CONTAINMENT Exemption Requested Redundunt trains of pressurizer level instrumentation circuitry within the Containment are located within approximately 6 feet of one another. The existing fire protection measures are not in accordance with the methods speciffi. 5y Section III.G.2 of Appendir R, but as discussed below,'the-existing f.re protection is such that one train of these cirenits would be free of Ire damage. An exemption is requested from Section III.G.2 of Appendix R to 10L.(50, pursuant to 10CFR50.12, to obviate the need for the installation of modifications to the existing fire protection measures for the pressurizer level instrumentation in the Containment.
Discussion i The independent transmitter and circuits for the three crains of pressurizer level instrumentation are located within approximately 6 feet of one another j in Fire Zone D-15. The three transmitters are located side-by-side to one another on the exterior of the concrete D-ring at the 585 foot elevation of :
the Containment, Room 317, Fire Zone D-15. The Channel 1 and 2 transmitters are approximately 6.5 feet apart, with the sving transmitter, Channel 1/2, located in the middle. The cabling drops from their respective tranrritter for approximately 4 feet in flexible metal conduit until they enter thtac metal junction boxes. The Channel 1 cabling (LT-RC-14-3) rises approximately 8 feet from its associated metal junction box and continues around the D-ring till it exits its penetration on the west side of the Containment. The Channel 2 cabling (LT-RC-14-1) drops approximately 3 feet from_its associated 1 metal junction box and proceeds around the D-ring in a direction opposite to j the Channel 1 conduit till it exits its penetration on the east side of the Containment. The Channel 1/2 cabling exits its metal junction box and follows the Channel 1 circuit. The transmitters and cables are contained in metel enclosures (rigid metal conduits, metal electric junction boxes, metal ,
transmitter housing and flexible metal conduits) which provides protection from radiant energy produced by a fire. However, this protection would not satisfy the NRC guidance for a 1/2-hour rating stated in Generic Letter 86-10 (Log Number 1983) nor Toledo Edison's commitment for a 1-hour fire rated-barrier, as stated in letter dated May 27, 1987 (Serial Number 1361). ,
l As discussed in the Davis-Besse Fire Hazards Analysis Report (FHAR), Section 2 5.D, the containment has a combustible loading of approximately 16,000 BTU /ft !
consisting mainly of flame-retardant cable insulation and reactor coolant pump lubricant oil. Fire Zoge D-15, within the Containment, has a combustible ,
loading of 5,000 BTU /ft primarily attributed to the flame-retardant cable insulation in 3 stacks of cable trays, located approximately 3. feet above the transmitters. The cable trays have solid metal bottoms, and the cables are protected against protracted faulted conditions by overcurrent devices.
Fire detection in the Containment is described in the FHAR, Section 5.D and-consists of 58 ionization type fire detectors, with Fire Zone D-15 containing 26 detectors. The fire suppression for the Containment relies on manual suppression involving portable extinguishers and fire hoses.
Docket Number 50-346
- Licensa Number NPF-3 Serial Number 1694 Attachment 1 Page 3J ,
Evaluation Toledo Edison has evaluated the existing fire protection measures provided for the Containment and has determined that these measures provide a level of protection equivalent to Section III.G of 10CFR50, Appendix R. These measures are:
- 1. As described in the FHAR, Section 5D,.the only significant combustibles in the Containment are flame retardant cable insulation and reactor coolant pump lubricant oil'. The Containment was evaluagedtohaveacombustibleloadingofapproximately16,000 BTU /ft . The pressurizer level transmitters are located in Fire Zone D-15vjthintheContainmentandhasacombustibleloadingof5,000 BTU /ft . Toledo Edison does not consider the combustible loading in the Containment to be significant relative to the location of the pressurizer level transmitters and cabling.
- 2. The reactor coolant pumps are separated from the pressurizer level !
transmitters by the concrete D-ring missile barriers. The two reactor coolant pump oil collection systems are seismically supported and vill be able to collect lube oil from potential. pressurized and unpressurized leakage sites in the four rear. tor coolant pump lube oil systems. The remaining modification to the collection systems, scheduled to be completed by restart from the sixth refueling outage, is to replace the collection funnels with flex hosing to prevent an overflow of these funnels during an oil leakage of greater than 5 gpm. Additionally, the NRC has reviewed the design of the oil collection systems and, as documerted in letter dated August 20, 1984 (Log Number 991), approved an exemption from 10CFR50, Appendix R, Section III.0 to the extent that oil collection tanks can not hold the entire lube oil system inventory. Toledo Edison considers the reactor coolant pump oil collection systems at Davis-Besse to be adequate to prevent an exposure fire hazard to the pressurizer level ;
transmitter and cabling. j
- 3. The cable insulation in the Containment and the jacket material of the flexible metal conduit enclosing a portion of the pressurizer level circuits satisfies the criteria of IEEE 383 or equivalent and would not sustain combustion unless an external heat source is i present. The ignitibility of cables at Davis-Besse was discussed in Toledo Edison letter dated February 8, 1988 (Serial Number 1471). !'
Additionally, the cables are protected against protracted faulted conditions by overcurrent devices. -Cable trays in the Containment '
have solid metal bottoms. Toledo Edison considers that cables
- located in the Davis-Besse Containment do not represent an exposure i
fire hazard.
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( Docket' Number 50-346 j
. ' License Number NPF-3 '
Serial' Number 1694 J Attachment 1 l Page 4. )
- 4. While personnel can enter the Containment in unusual conditions at !
power and during plant shutdown under controlled conditions, l transient combustibles that a rc introduced in the Containment are -l minimized and the Containment areas are inspected for loose debris (rags, trash, clothing, etc.) prior to establishing Containment integrity in accordance with Technical Specification 4.5.2.c. .These i inspections are documented and implemented using administrative 'l procedures. i
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- 5. The Containment contains 58 ionization type fire detectors in ten I fire detection zones. ' Fire Zone D-15 contains 26 of these fire .
detectors. Each detector alarm ir. the Containment activates its.
associated fire detector zone local panel, both visually and audibly.
The alarm condition of each of these panels is both visually and audibly. alarmed in the Control Room via the Fire Detection System / Radiation Monitor System console. A visual and audible indication is also located on the Main Control Board to indicate an alarm on this console.
- 6. The fire suppression for the Containment consists of manual suppression involving portable fire extinguishers and fire hoses. In the event that a fire inside the containment occurs during a refueling or maintenance outage, a fire hose vould be connected to the fire department connection at Hose Station 27 located outside the containment and brought into the Containment by overriding the mechanical interlock of the personnel air lock access door.
- 7. Cables for the pressurizer level transmitters are in metal enclosures (rigid metal conduits, metal electric junction boxes and flexible metal conduits). These metal enclosures provide limited protection from radiant energy produced by a fire, but are not sufficient to satisfy the 1/2-hour rating stated in Generic Letter 86-10 (Log Number 1983). Fire Zone D-15, which contains the pressurizer level transmitters, is separated from portions of the Containment by the concrete D-ring and the concrete floor. -
- 8. The Davis-Besse Fire Brigade has a' minimum shift size of 5 members and is onsite at all times in accordance with Technical Specification 6.2.2.F. The Fire Brigade'does not include the members of the minimum shift crew necessary for safe shutdown of Davis-Besse during a fire emergency. The Fire Brigade has established training programs and fire drills under existing administrative controls.
The Fire Brigade vould respond to a determination of a fire in the Containment. During normal plant operations, fire fighting personnel accessed to the Containment may be delayed due to personnel radiation hazards. The delay-to enter the containment would be' determined based upon the extent of the fire and its impact on the capability to achieve and maintain safe shutdown.
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Docket Number 50-346 License Number NPF-3 Serial Nunber 1694 Attachment 1 Page 5
- 9. The Davis-Besse Fire Brigade is_self sufficient with respect to firefighting activities. However, the Carroll. Township Fire Department, the lecal fire department, provides a supplemental and backup capability. The local public fire departn'ent is invited at least annually and frequently participates in drills at Davis-Besse..
- 10. The Davit.-Besse Appendix R Compliance Assessment Report, Section 4.3 states: "Unless they are ignition sourceJ, passive mechanical components are assumed to retain functional during and after a fire.
These components include heat exchansers, manual and check valves, piping nnd tanks." The steel instrument tubing for the pressurizer level transmitters is considered to be a passive mechanical component and is assumed to remain functional. The instrument tubing-and the fluid within the tubing would not be adversely affected by heat from a postulated fire due to limited combustibles in the area.
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Consequently, Toledo Edison has determined that the existing fire protection features provided for the Davis-Besse Containment would ensure at least one train of systems necessary to achieve and maintain hot standby is free of fire damage and, thereby, provirle an equivalent level of fire protection as required by Section III.G of Appendix K. Additionally, the imposition of additional modifications simply to satisfy the methods specified by Appendix R-of 10CFR50 for the Containment vould not significantly enhance the level of I
fire protection currently provided.
Applicable Special Circumstance Toledo Edison has datermined that the requested exemption conforms to the applicable exemption criteria of 10CFR50.12(a). There are no prohibitions of ,
law to preclude the activities that vould be authorized by the requested !
exemption, and the requested exemption, if granted, would have_not impact on the common defense and security. Additionally, the requested exemption does ,
not present an undue risk to the public health and safety since an equivalent !
level of fire protection as required by Section III.G of Appendix R is j provided as described above. I Special circumstances are applicable to the requested exemption in accordance with 10CFR50.12(a)(2)(ii) in that application of the regulation for these i particular circumstances is not necessary to achieve the underlying purpose of the rule. Section Ill.G of 10CFR50, Appendix R specifies methods to ensure one train of systems necessary to achieve and maintain hot standby is free of i' fire damage. The underlying purpose of the rule is satisfied by the requested exemption since the existing fire protection features described above provide an equivalent level of fire protection as required by Section III.G of i Appendix R and the completion of modifications simply to satisfy the methods specified by Appendix R is not necessary.
Additional special circumstances are applicable to the requested exemption in l
accordance with 10CFR50.12(a)(2)(iii) in that the application of the I regulation vould represent an unwarranted burden on Toledo Edison resources i
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Docket Number 50-346 )
- License' Number EPF-3 '
Serial Number 1694 Attachment 1 Page 6-and the costs may be in excess of those incurred by another utility similarly situated as Davis-Besse. The modification of the current containment fire protection features vould result in considerable expenditure of engineering,
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construction and plant staff resources for its installation, maintenance and operation. The associated costs would include:
Engineering and installation of radiant energy shield material and supporting structures or the relocation of one pressurizer transmitter, instrument tubing and cabling.
Implementation of increased surveillance and maintenance requirements for the radiant energy shield.
A radiant energy shield could impair the qualified life of the pressurizer level transmitters and their operation due to the heat buildup in the enclosed transmitter.
A radiant energy shield could inhibit the performance of CHANNEL CALIBRATION surveillance testing of the pressurizer level instrumentation required by the Technical Specification and could result in additional man-rem exposure.
A radiant energy shield er relocation of one~ train of pressurizer level instrumentation vould increase congestion in the Containment, complicating future plant modifications and operation.
The high costs associated with the modification to the Containment fire.
protection features would represent an unwarranted burden on Toledo Edison resources considering the resulting negligible safety benefit and the alternative means of fire protection described above. Additionally, another nuclear power plant, which Toledo Edison believes is similarly situated as '
Davis-Besse, has been granted a comparable exemption by the NRC.
In conclusion, Toledo Edison considers that special circumstances in accordance with 10CFR50.12(a)(2)(ii) and 50.12(a)(2)(iii) are present to justify the requested exemption. The completion of additional modifications simply to satisfy the methods specified by Appendix R of 10CFR50 is not necessary to satisfy the underlying purpose of the rule since the existing fire protection features provided for the Davis-Besse Containment would ensure one train of systems necessary to achieve and maintain hot standby is free of fire damage and, thereby, provide an equivalent level of fire protection as required by Section III.G of Appendix R. Additionally, the completion of additional modifications simply to satisfy the methods specified by Appendix R of 10CFR50 represents an unwarranted burden on Toledo Edison resources considering the resulting negligible safety benefit and the exemption previously granted to another utility similarly situated as Davis-Besse.
Docket Number 50-346 Licensa Number NPF-3 Serial Number 1694 Attachment 1 Page 7, REDUNDANT TRAINS OF CIRCUITS IN MANHOLE Exemption Requested Redundant trains of Service Vater System and essential power circuits located in manhole MH 3001 are located less than 6 feet from one another. The existing fire protection features for the manhole are not in accordance with the methods specified by Section.III.G.2 of 10CFR50, Appendix R, but as discussed below, these fire protection features are sufficient to ensure that one train of these redundant circuits vould be free of fire damage. An exemption is requested from Section III.G.2 of Appendix R to 10CFR50, pursuant to 10CFR50.12, to obviate the need for modifying the present fire protection measures for manhole MH 3001.
Discussion Manhole MH 3001 contains redundant circuits associated with:
- 1) Service Water Pumps (P3-1, P3-2, and P3-3),
- 2) Backup Service Water Pump (P-180),
- 4) Motor control centers (HCCs E12C and F120), which provide power to Service Vater valves and other components supporting the operation of the Service Water System, such as ventilation fans.
Manhole MH 3001 is an underground concrete box, measuring 6' x 13' x 12' deep and is considered a separate fire area. A l' thick concrete vall in the center of the manhole separates it into equal portions. The power cables for train 1 and 2 Service Water Pumps are located on one side of the manhole, and the power circuits to MCCs E12C and F12C and the train 1 and 2 control cables for the pumps and service water valves are on the other side.
Essential power and Service Water System circuits are routed through the manhole in metal virevays, except the power cable (2 PAD 107A) for one of the Service Water Pumps (P3-2) and the power cable for the Backup Service Water Pump.
Virevays are equivalent to cable trays with solid tops, bottoms and sides.
Virevays are provided to maintain the horizontal and vertical separation criteria outlined in Appendix 1 of Regulatory Guide 1.75 and to eliminate bridging, which is the simultaneous grouping of a nonessential cable with cables or conductors of two different essential trains.
The combustible loading of the manhole is approximately 29,800 BTU /ft* vith 29,400 BTU /ft 2 due to cable insulation and the remainder due to grease in the sump pump and incidentals. The cables are evenly split between each side of the manhole, with approximately 37% of the cables enclosed in metal'virevays. a .,
cable insulation throughout the plant satisfies the criteria of IEEE 383-1974 or its equivalent and vill not sustain combustion unless an external heat source is present. The cables are protected against protracted fault conditions /
overcurrent devices.
Docket Number 50-346 License Number NPF-3 Serial Number 1694 j
Attachment 1 Page 8 The floor slab of the manhole is sloped to allow any liquids to accumulato ~n the sump on the northern side of the manhole; holes in the bottom of the anter ll vall allov liquids from the southern side of the manhole to accumulate in the i sump. Each side of the manhole extends 10 to 12 inches above the ground and is capped by a 7/16 inch thick steel plate, which is bolted to an elevated concrete f lip around each opening. Each plate has an 1 inch downward lip that overlaps the elevated concrete lip. Entry into the manhole is controlled by an entry permit system as described in Davis-Besse procedure HS-SF-00004, Safe Vork Procedure for Confined Spaces. Transient combustibles are controlled and limited by Davis-Besse procedure, DB-FP-00007 Control of Transient Combustibles.
i' The manhole is located outside of the Davis-Besse power block, but within the protected area of the plant. About 1 foot from the manhole is a small stor:$e shed that is used for the storage of drums of vaste oil and hazardous and chemical vaste, which are avaiting disposal. The shed is design to retain any spillage, is Factory Mutual approved and has no openings but a door, which is normally locked. The door is on the side of the shed facing away from the manhole. The storage of vaste in the shed is controlled by Davis-Besse procedure NG-HS-00504, Hazardous and Non-hazardous Chemical Vaste Management.
Manual fire suppression capability consists of two hose houses (HH16, HH1),
which are approximately 90 feet and 200 feet from the manhole. Sufficient fire hose is maintained at each hose house to provide manual suppression at the area of the manhole.
Evaluation Toledo Edison has evaluated the existing fire protection measures provided for manhole MH 3001 and has determined that these measur's e provide a level of protection equivalent to Section III.G of 10CFR50, Appendix R. These measures are:
- 1) The only significant combustible in the manhole is flame retardant cable. insulation amounting to a combustible loeiing of approximately 29,400 BTU /ft 8
, of which approximately 11,400 BTU /ft' is in metal wirevays.
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- 2) Essential power and Service Water System cables are routed through the manhole in metal wirevays, except the power cable (2 PAD 107A) for one of the Service Water Pumps (P3-2) and the power cable for the Backup Service Water Pump. Wirevays are equivalent to cable trays with solid tops, bottoms and sides. Virevays are provided to maintain the i horizontal and vertical separation criteria outlined in Appendix 1 of
. Regulatory Guide 1.75 and to eliminate bridging. Any fire vould not propagate from one system train to the other. Thus, the availability of one train of Service Water and one MCC is assured despite a fire in any circuitry in the manhole. -
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Dock.et Number 50-346 License Number NPF-3 Serial Number 1694 Attachment 1 Page 9 The cable insulation in the manhole satisfies the criteria of
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IEEE 383-1974 or equivalent and vould not sustain ' combustion un? ess an external heat source is present. Additionally, the cables are protected against protracted faulted conditions by overcurrent devices.
- 4) Entry Anto the manhole is controlled by an entry permit system and the manhole is bolted closed. Transient combustibles are controlled and limited procedurally. Thus, administrative controls limit personnel entry into the manhole and the introducidon of transient combustibles into the manhole, as well as. effectively eliminating the potential;for.
a significant transient combustible fire in the manhole that could l disable the Service Water System or essential povcs.
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- 5) The design features of the manhole openings and the storage shed effectively eliminate the possibility cf any potential ~ liquid spill-stored in the shed from entering the manhole, The openings into the manhole and the door of the shed are located at least 6 inches above ground. Any spill 1 rge enough to exceed the holding capacity of the shed would not drain into the manhole, f
f 6) The Davis-Besse Fire Brigade has a minimum shift size of 5 members and j
is onsite at all times in accordance with Technical Specification 6.2.2.f. The Fire Brigade dues not include the-members of the minimum shift crev necessary for safe shutdown of Davis-Besse during a fire emergency. The Fire Brigade has established training programs and fire drills under existing administrative controls. The hose houser provide for the manhole are sufficieni for the Fire Brigade to manu:J1y suppress a potential fire at the manhole.
Consequently, Toledo Edison has determined that the existing level of fire protection provided for the manhole MH 3001 vould ensure one train of Service Water and Essential Power is fu e of fire damage, thereby, providing an equivalent level of fire protection as required by Section III.G of Appendix R.
Additionally, the imposition of t.iditional modifications simply to satisfy the- j methods specified by Appendix R cf 10CFR50 for the manhole veuld not -l significantly enhance the level of fire protection currently provided. l l
Applicable Special Circ'imstance Toledo Edicon has determined that the requested exemption conforms to the applicable exemption criteria of 10CFR50.12(a). There are no prohibitions of ;
law to preclude the activities that would be authorized by the requested .
exemption, and the requested exemption, if granted, vould have no impact on.the ;
common defense and security. Additionally, the requested exemption does not i present an undue risk to the public health and safety since an equivalent' level !
of fire protection es required by Section III.G of Appendix B is provided as i described above.
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i Docket Number 50-346 I License Number NPF-3 l Serial Number 1694 !
Attachment 1 Page 10' j
Special circumstances are applicable ta the requested exemption in accordance with 10CFR50.12(a)(2)(ii) in that application of the regulation for these particular circumstances is not necessary to achieve the underlying purpose of the rule.Section III.G of 10CFR50, Appendix R specifies methods to ensure one -!
train of systems necessary to achieve and maintain hot standby is free of fire !
damage. The underlying purpose of the rule is satisfied by the requested !
exemption since the existing fire protection features described above provide an -.
equivalent level of fire protection as required by Section III.G of Appendix R l and the installation of modifications simply to satisfy the metherla specified by 1 Appendix R is not necessary.
Additional special circumstances are applicable to the requested exemption in accordance with 10CFR50.12(a)(2)(iii) in that the application of the regulation would represent an unwarranted burden on Toledo Edison resources and the costs may be in excess of those incurred by another utility similarly situated as 3 Davis-Besse. The modification of the current fire protection features would l result in the considerable expenditure of engineering, constrt.etion and' plant j staff resources for its installation, maintenance and operation. The associat.ed J coe.s vould include:
Engineering, construction and installation of 3-hour fire barriers for the control and power cables in the manhole or rerouting the cables.
Increased surveillance and maintenance of the 3-hour fire barriers.
Fire barriers in the manhole or relocation of the power and control cables would increase congestion, complicating future plant modifications and operation.
The high costs associated with modification of the existing fire protection j festures for manhole MB 3001 vould represent an unwarranted burden on Toledo <
Edison resources considering the resulting negligible safety benefit and the alternative means of fire protection described above. Additionally, another ;
nuclear power plant, which Toledo Edison considers to be similarly situated as ;
Davis-Besse, has been granted a comparable exemption. ;
In conclusion, Toledo Edison considers that special circumstances in accordance {
with 10CFR50.12(a)(2)(ii) and 50.12(a)(2)(iii) are present to justify the l requested exemption. The imposition of additional modifications simply to ]
satisfy the methods specified by Appendix R of 10CFR50 is not necessary to . {
satisfy the underlying purpose of the rule since the existing fire protectien' '
features provided for ranhole MH 3001 vould ensure one train of' systems :
necessary to achieve and maintain hot standby is free of fire damage, thereby- I providing an equivalent level of fire protection as required by Set ion III.G of j Appendix R. Additionally, the imposition of additional modifications simply to '
satisfy the methods specified by Appendix R of 10CFR50 represents an unwarranted burden on Toledo Edison resources considering the resulting negligible safety i benefit and the exemption previously granted to another utility. J l
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y Docket Number 50-346 License Number NPF-3 Serial Number 1694 Attachment 1 i Page 11 EMBEDDED CONDUITS Exemption Requested Certain circuits required to achieve and maintain safe shutdown in the event of a fire are enclosed in conduit and embedded in concrete valls, floors and ceilings of the Davis-Besse Nuclear Power Plant. These circuits were not evaluated in the safe shutdown analysis for a fire and the existing fire protection features for these circuits are not in accordance with the requirements of Section III.G of Appendix R to 10CFR50. However, as discussed below the tire protection features are sufficient to ensute one train of these circuits would be free of fire damage. An exemption is requested from Section III.G of Appendix R to 10CFR50, pursuant to 10CFR50.12, to obviate the need for modifying the existing fire protection features for these circuits embedded in concrete.
Discussion The cables required for safe shutdown in the event of a fire and embedded in concrete are listed under Fire Area EMB in Appendix B-2 of the Davis-Besse Appendix R Compliance Assessment Report (CAR). These cables are enclosed in j conduit. Although the conduit embedment depth at Davis-Besse is not specially dimensioned on design drawings, it is known that a minimum of 2 inches of concrete cover over the rebar for structures containing condtlit was required.
Two rebar mats are used in reinforced concrete valls at Davis-Besse, each comprieing of two layers of the rebar running perpendicular to eacn other. ;
since the minimum nominal thickness of the rebar used in wells is 3/4 inches, 1 this configuration of the reinforced concrete valls provides a minimum conduit embedment of 3% inches (1% inches of rebar covered by 2 inches of concrete),
assuming the conduit is tied between the two rebar mats. Two rebar mats are used in ceilings / floors at Davis-Besse, consisting of two layers of rebar with a i nominal thickness of 5/8 inches. This configuration provides a m3nimum conduit embedment of 3% inches on the floor side of the reinforced ceilings / floors (1% inches of rebar covered by 2 inches of concrete), assuming the conduit is j tied beneath the rebar mat.
The NFPA Handbook, 16th Edition, indicates that 3% inches of concrete provides approximately 80 minutes of fire resistance (Figure 7-8F). Toledo Edison has also analyzed the potential impact of anchor bolts on the fire resistance of the concrete valls, floors and ceilings. This analysis has demonstrated that the internal conduit temperature vould not exceed 350'F based on the configuration of conduit embedment, as describ.d above, and the standard heat input specified by ASTM E-119 time-temperature curves. Cables er. closed in conduit and embedded in concrete are considered capable of performing their intended function if their temperature is maintained belov 350'F, which is less than their melting point and ignition point. This analysis concluded that the anchor bolts did not affect the fire resistance of the concrete valls, floors and ceilings.
Currently, with the exception of Fire Areas P and Y, the fire areas having valls, floors or ceilings with embedded conduits either have a combustible loading of 30 minutes or Jess or are protected by an automatic sprinkler system.
Fire Area Y, Lov Voltage Switchgear Roci 429, currently has a combustible loading of 61,420 BTU /ft .8 Fire Area P, Passageway 322, has a combustible loading of 51,669 BTU /fta, i
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,l Docket Number 50-346 License Number NPF-3 ;
Serial Number 1696 j Attachment 1 Page 12 Thirty-six percent of the loading in Fire Area Y is due to cable insulation (Type.A hazard), and sixty-three percent is due to transformer coolant (Type B 1 hazard), which is classified as a "Non Flammable" material as' defined by Section .]
450.24 of the 1987 National Electric Code. The reinainder of the combustible I loading consists of small quantities of grease (Type B hazard) and incidentals combustibles. Ninety-nine percent of the loading in Fire Area P is due to. cable insulation (Type A Hazard) with the remainder consisting of incidental I combustibles.
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In early 1990, Toledo Edison plans te replace the transformer coolant in Fire Areas X and Y vith a silicone-based coolant, which is classified.as a "Less Flammable" material as defineo by Section 450.23 of the 1987 National Electric Code. This vill raise the combustible loading of Fire Atea Y to 91,700 BTU /ft*
(approximately 1.2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />). The combustible 30asing of Fire Area X, Lov Voltage Switchgear Room 428, vill increase from 35,980 BTU /ft 2 to 52,640 BTU /ft8 (approximately 0.7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br />) At that time, twenty-six percent of the combustible loading of Fire Area X vill be due to cable insulation (Type A hazard) and seventy-three percent will be due to the silicone-based' transformer coolant (Type B hazard). The remainder of the combustible loading in Fire Area X vould be due to small quantities of grease (Type B hazard), inc? yentals and normal transient combustibles.
The embedded conduits in Fire Area Y are located in the floor. Certain embedded conduits in Fire Area X are in a ductbank along the vest vall. Certain conduits are also located in the reinforced ceiling / floor between Fire Area X and P.
fire detection is provided for Fire Areas P, X and Y.
Evaluation Toledo Edison has evaluateo the existing fire protection measures provided for embedded conduits and has determined that these measures provide a level of protection equivalent to Section III.G of 10CFR50, Appendix R. These measures q are:
- 1. Conduits embedded in ralls and ceilings / floors have a minimum embedment of at least 3% inches of concrete, which provides a fite. .
resistance of at least 60 minutes. This fire resistance exceeds the }
combustible loading of those fire arcas having a combustible loading l of 30 minutes or less and vill maintain the circuits free of fire j damage. Other than Fire Area P,'X and Y, those fire areas with a 1 combustible loading of greater than 30 minutes are provided with f automatic sprinkler systcms. In those fire areas, the passive )
protection of the concrete and the active protection provided by the j automatic sprinkler systems vill maintain the conduits free of fire i damage.
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- 2. Currently, more than sixty percent of the combustible loading for Fire j Area Y consist of "Non Flammable" transformer toolant, After the replacement of the transformer coolant with the silicon-based coolant in early 1990, mote than sixty percent of the combustible loading for Fire Areas X and Y vill consist of 'Less Flammable" transformer ;
coolant. The existing transformer coolant and the silicon-based l coolant have a flash point of not less than 300*C. The majority of. ;
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Docket Number 50-346 Licenan Number NPF-3 Serial tamber 1694 Attachment ?
Page 13 the remaining combustibles in these two fire areas consists of cable insulation, which satisfies the criteria of IEEE 383 or equivalent and vill not sustain combustion unless an external heat source is present.
Consequently, it is unlikely that sufficient heat would be generated to damage the conduits in the ductbank in the vest vall, vbich is away from the majority of the fire loading or that sufficient heat vould be delivered downward to the floor to damage the embedded conduits.
.i . Fire Area P is a small area with a relatively lov total combustible lot. ding which is ninety-nine preent cable insulation. The cable insulation satisfies the criteria of IEEE 383 or equivalent and vill not sustain combustion unless an external heat source is present.
Consequently, it is unlikely that sufficient heat would be generated to damage the embedded conduits.
- 4. Fire Areas P, X and Y are provided with' fire detection zones which would alert Control Room personnel, who would initiate'the response of the Fire Brigade..
- 5. The navis-Besse Fire Brigade has a minimum shift size of 5 raembers and is onsite at all times in accordance with Technical Specification 6.2.2f. The Fire Brigade does not include the members of the minimum shift crew necessary for safe shutdown of Davis-Besse during a fire.
emergency. The Fir? Brigade has established' training programs and fire drills under existing administrative controls.
Consequently, Toledo Edison has determined that the existing fire protection features provided for the embedded conduits vould ensure one train of equipment necessary to achieve and maintain safe shutdown in the event-of a fire is free of fire damage and, thereby, provide an equivalent level of fire protection as required by Section III.G of Appendix R. Additionally, the imposition of additional modificati0ns simply to satisfy the methods specified by Appendix R of 10CFR50 for the manhole would not significantly enhance'the level of fire protection currently provided.
Applicable Special Circumstance Toledo Edison has determined that the requested exemption conforms to the applicable e,xemption criteria of 10CFR50.12(a). There are no. prohibitions of I
law to preclude the activities that would-be authorized by.the requested exemption, and the requested exemption, if granted, vould have no impact on the common defense and security. Additionally, the requested exemption does not present an undue risk to the public health and safety since an equivalent level 1 of fire protection an required by Section III.G of Appendix R is provided as' j described above.
Special circumstances are applicable to the requested exemption in accordance j l
vith 10CFR50,12(a)(ii) in that application of the regulation for these particular circumstances is not necessary to achieve and maintain hot standby is l'
free of fire damage. The underlying purpose of the rule is satisfied by the requested exemption since the existing fire protection features described above y i
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Docket Number 50-346
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Serial Number 1694 'f Attachment 1 Page 14 provide an equivalent level of fire protection as required by Section III.G of Appendix R and the installation of modifications simply to satisfy the methods specified by Appendix R is not necessary.
Additional speciel circumstances are applicable to the requested exemption in accordance with 10CFR50.12(a)(iii) in that the application of the regulation would represent an unwarranted burden on Toledo Edison resources. The modification of the current fire protection features for the embedded conduits vould result in the considerable expenditure of engineering, construction and
!' plant staff resources for its installation, maintenance and operation. The associate costs would include:
l Engineering, construction:. and installation of fire barriers on valls
! and floors or increase the concrete embedment to achieve a 3-hour fire l rating through many areas of the plant.
l Increased surveillance and maintenance of the fire barriers.
Fire barriers on valls and floors or the increase in the concrete embedment would significantly increase congestion in the plant, complicating future plant modifications and operation.
The high costs associated with modification of the existing fire protection features for embedded conduits vould represent an unwarranted burden on Toledo Edison resources considering the.resulting negligible safety benefit and the alternative means of fire protection described above.
In conclusion, Toledo Edison considers that special circumstances in accordance with 10CFR50.12(a)(2)(ii) and 50.12(a)(2)(iii) are present to justify the requested exemption. The imposition of additional modifications simply.to satisfy the methods specified by Appendix R of 10CFR50 is not necessary to satisfy the underlying purpose of the rule since the existing fire protection features provided for embedded conduits vould ensure one train of systems necessary to achieve and maintain hot standby is free of fire damage and, thereby, provide an equivalent level of fire protection as required by Section III.G of Appendix R. Additionally, the imposition of additional modifications simply to satisfy the methods specified by Appendix R of 10CFR50 represents an unwarranted burden on Toledo Edison Resources considering the resulting negligible safety benefit.
ATTACHMENT 2 Irglementation g of Previously Approved Exemptions i
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i Docket Number 50-346 j License Number NPF-3 l l
Serial Number 1694 !
Attachment 2 J Page 1 IMPLEMENTATION OF PREVIOUSLY APPROVED EXEMPTIONS Introduction The NRC has previcesly approved five Appendix R exemptions for Davis-Besse in letters dated December 3, 1982 (Log Number 1138) and August 20, 1984 (Log Number 1586). Since these exemptions were approved, Toledo Edison has been ,
implementing numerous Appendix R corrective actions and enhancements to the-Davis-Besse fire protection program. The following is a discussion of three of the five Appendix R exemptions.
CCV Pump Room This exemption was requested in Toledo Edison letter dated April 29, 1982 (Serial Number 815) and was approved by the NRC in letter dated December.3, 1982 (Log Number 1138).- Toledo Edison justified the alternative proposed by the exemption request, in part, by the following:
- 1. Selected conduits and valves which were required for safe shutdown are protected by a 1-hour fire barrier. Table 1 of the exemption request identifies the conduits and valves that are protected by the 1-hour fire barrier and were considered to be required for safe shutdown.in the event of a fire.
- 2. The fire loading in the CCV Pump Room based on fixed combustibles was 392 BTU /ft2 .
The current safe shutdown analysis for Appendix R has revised the list of equipment required to achieve safe shutdown in the event of a fire and no longer requires certain conduits and valves identified by Table 1 of Serial Number 815.
Although the 1-hour fire barriers are still required by the Davis-Besse fire protection program for conduits and vcives identified by Table 1 of Seriel Number 815, those fire barriers on conduits and valv>& that are no longer necessary to achieve and maintain safe shutdown'in the event of a fire are expected to be removed. Removal of unnecessary fire barriers vill' streamline fire barrier surveillance activities, maintenance and,other plant activities that require temporary removal of the fire barrier to access the underlying -
c.freuits, reduce congestion in the area, and contribute to improved housekeeping. Removal of the fire barriers vould be considered as a change in the Toledo Edison icense, which will be addressed in a later submittal.
The Davis-Besse Fire Hazards Analysis Report, Section 5.T documents that the current fixed fire loading in the CCW Pump Room,. Fire Area T, is 1332 BTU /ft8, which exceeds that previously stated in the approved' exemption request. The NRC approved the exemption for the CCV Pump Room based, in part, that, "The in-situ combustible loading is significantly less than that needed for a fire of one hour duration". The current fixed fire loading of 1332 BTU /ft2 is still
- r. significantly less than that required for a fire of one hour duration and, therefore, is consistent with the exemption approved by.the NRC.
-Docket Number 50-346 License Number NPF-3 Serial Number 1694 Attachment 2 Page 2 Door 215 This. exemption was requested in Toledo Edison Letter dated September 30, 1983 (Serial Number 991) and was approved in NRC letter dated August 20, 1984 (Log Number 1586). The exemption was necessary at the time'to address Door 215, I which was not a UL-rated fire door, but installed in a 3-hour fire vall separating the two auxiliary feedvater pump rooms. Toledo Edison has since replaced this Door 215 with another door that has been evaluated as being equivalent to a 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> rated door, although not labeled. The construction of the current door is different from the original, but is considered by Toledo Edison to be addressed by the existing exemption request.
RCP Oil Collection System This exemption was requested in Toledo Edison letter dated September 30, 1983 (Serial Number 991) and was approved in NRC letter dated August _20,1984 (Log ,
Number 1586). This exemption was necessary since the capacity of the tanks for the RCP Oil Collecticn System is not sufficient to hold the entire lube oil system. Toledo Edison description of the RCP Oil Collection System included a statement that, "The tank [of the RCP Oil Collection System] is periodically emptiec to assure adequate capacity for the oil contained in one [RCP] motor at all timas while the reactor is critical." Toledo Edison justified the limited capacity of the tanks of the RCP Oil Collection System by confirming that the tank votvid discharge via an air vent pipe to a floor drain to the containment sump.
The location of the tanks prevents access during power operation to perform draining, It should be noted that the tanks are inspected periodically and emptied when the level in the tank exceeds 5 inches at shutdown, which is still sufficient to collect the lube oil in one RCP motor. However, due to fluid accumulation from normal condensation, for example, the tanks may not be able to collect the lube oil from one RCP motor at all times between inspection and draining.
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Nonetheless, the justification and conclusion of the exemption is unchanged. As stated in Toledo t Mson's request for the exemption and the NRC's approval, any I overflow from the :1 collection tanks would be ultimately discharged to the containment sump an, away from the presence of ignition sources.
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