3F0296-26, Requests Exemption from Section III.G.2 of 10CFR50,App R,As Applies to Certain Redundant Cables & Equipment in Reactor Containment Bldg

Requests Exemption from Section III.G.2 of 10CFR50,App R,As Applies to Certain Redundant Cables & Equipment in Reactor Containment Bldg

ML20100J744
Person / Time
Site:	Crystal River
Issue date:	02/26/1996
From:	Boldt G FLORIDA POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
3F0296-26, 3F296-26, NUDOCS 9602290238
Download: ML20100J744 (23)

Text

.______ ______-__ - ___

4 Florida Power CORPORATION 07eE February 26, 1996 3F0296-26 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555

Subject:

Appendix R Revised Exemption Request, Reactor Containment Building

References:

A. FPC to NRC letter, 3F0195-03, dated January 6, 1995 B. FPC to NRC letter, 3F0296-09, dated February 15, 1996

Dear Sir:

Pursuant to 10 CFR 50.12(a), Florida Power Corporation (FPC) requests an exemption from Section III.G.2 of 10 CFR 50, Appendix R as it applies to certain redundant cables and equipment in the Reactor Containment Building at Crystal River Unit 3 (CR-3). This request is supported by an attached analysis which includes (1) the specific exemption requested, (2) information on fire protection systems at CR-3 for the area where the exemption request applies, (3) the bases for the exemption, and (4) a technical evaluation of the request. The attached analysis demonstrates that the combination of existing conditions and fire protection features provides adequate protection of the public health and safety and satisfies the exemption criteria of 10 CFR 50.12(a). Accordingly, the exemption should be granted.

FPC committed to having an action plan for resolution of the Thermo-Lag radiant energy shields and containment penetration barriers inside the Reactor Containment Building in Reference A. This was stated in "FPC Response to VI.B.2," item 4. Reference B is a previous exemption request for the same fire areas. This exemption request replaces Reference B in its entirety and constitutes FPC's action plan for the Thermo-Lag radiant energy shields and containment penetration barriers noted in Reference A.

9602290238 960226 PDR ADOCK 05000302 P PDR CRYSTAL RIVER ENEH3Y COMPLEX: 15700 W. Power une Street . Crystal River, Floride 344284708 e (352) 795 6486 A Rorida Progress Company 290061 p60 Ili

+ U. S. Nuclear R:gulatory Commission 3F0296-26 Page 2 of 14 Should you have any questions concerning this request, please call Mr. Bill Rossfeld at (% 2) 563-4374.

Sincerely, M

G. L. oldt Vice President Nuclear Production GLB/SCP:ff Attachment xc: Regional Administrator, Region II NRR Project Manager Senior Resident Inspector 1

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STATE OF FLORIDA 1

COUNTY OF CITRUS I l

1 l

G. L. Boldt states that he is the Vice President, Nuclear Production for Florida '

Power Corporation; that he is authorized on the part of said company to sign and file with the Nuclear Regulatory Commission the information attached hereto; and that all such statements made and matters set forth therein are true and correct to the best of his knowledge, information, and belief.

G. L. Bo t Vice President  !

Nuclear Production G. L. Boldt, personally known to me. Subscribed and sworn to before me, a Notary Public in and for the State and County above named, this 26th day of February, 1996.

l Lyar S Smd

- y dJ&h&r ..v Notary Public (print) Notary Public (signature) i LYNNE S. S4ITH My rmaanauw # CC 614300 '

l EXPNES: Deesmber 18,1980 sons fivu Netsy Piete unconsters '

l l U. S. Nuclear Regulatory Commission 3F0296-26 Page 3 of 14 ATTACHMENT

, APPENDIX R EXEMPTION REQUEST l REACTOR CONTAINMENT BUILDING l

1. Summary Florida Power Corporation (FPC) requests an exemption from the requirements of i 10 CFR 50, Appendix R, III.G.2, for certain redundant safe shutdown cables in the '

Reactor Containment Building (RB) Elevations 95 and 119. The cables are for i pressure and level instrumentation for the Reactor Coolant System and Steam '

Generators. To protect these cables from fire in accordance with Appendix R, FPC installed Thermo-Lag fire barriers to enclose one train of redundant safe i shutdown equipment and cables inside the RB. Based on vendor information l available at the time, these barriers were considered to be non-combustible radiant energy shields. FPC considers that the existing design and separation of the safe shutdown equipment and circuits inside the RB, protection of one train of redundant circuits with Thermo-Lag fire barriers within 20 feet of the RB penetration area, and fire detection not previously taken credit for, ensure an adequate level of fire protection. These features, plus strong administrative controls, together provide defense in depth protection which justifies this exemption request. Accordingly, the granting of this exemption will continue to '

ensure an adequate level of fire protection inside the Reactor Containment Building.

2. Backaround Crystal River Unit 3 (CR-3) was licensed to operate in December 1976. All plants licensed to operate before January 1,1979 are required to comply with, inter alia,10 CFR 50, Appendix R, Section III.G and 10 CFR 50.48(b). FPC modified CR-3 by adding fire protection features that, taken together, were considered adequate to comply with Section III.G of Appendix R. Those modifications included installation of Thermo-Lag fire barriers at CR-3. These were installed in 1984 and 1985 in support of FPC's due date for implementation of Appendix R in July 1985. An NRC Team Inspection was performed at CR-3 in July and August of 1985 in the areas of fire protection and FPC actions regarding the implementation of the requirements of Appendix R, Sections III.G, III.J, III.L, and 111.0. No violations or deviations were identified.

FPC continues to maintain a strong program of administrative controls over fire protection activities. Particular strengths include effective housekeeping, control of fire barrier breaches, control of hot work, control of transient combustible materials, and control of chemicals and flammable liquids. NRC i inspection reports have recognized effective FPC fire brigade performance during l drills and the effectiveness of CR-3 Pre-Fire Plans. The history of fire l protection inspections at CR-3 shows that although some minor violations and deviations have occurred, overall performance has been very good. This trend of continued good performance is reflected in the consistently positive evaluations during NRC Systematic Assessment of Licensee Performance (SALP), as reported in SALP Inspection Reports for CR-3.

Problems with the manufacturer's rating of Thermo-Lag fire barriers have resulted I in a re-evaluation of our basis for Appendix R compliance, and our use of Thermo-Lag to achieve compliance. FPC is now completing our re-evaluation, and determining the most effective measures to return to compliance. These measures

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U. S. Nuclear Regulatory Commission 3F0296-26 Page 4 of 14 include plant modifications, plant operations changes, installation of other fire barrier material over Thermo-Lag, replacement of Thermo-Lag, and submittal of exemption requests where justified.

FPC was granted approval for one exemption to Appendix R criteria in 1983, and six in 1985 which were important in establishing initial compliance. We anticipate that two of these will be determined to be unnecessary and two others will be modified. We further anticipate that up to four additional exemption requests will be submitted.

3. SDecific Exemotion Reauested 10 CFR 50 Appendix R, Section III.G.2 provides acceptable means for assuring that one train of safe shutdown cables and equipment will remain free of fire damage.

Three options are provided specifically for fire protection of cables and equipment of redundant safe shutdown trains inside non-inerted containments. The three options available only for areas inside containment as stated in Section III.G.2. paragraphs d, e, and f are:

d. Separation of cables and equipment and associated non-safety circuits of redundant trains by a horizontal distance of more than 20 feet with no intervening combustible or fire hazards;

e. Installation of fire detectors and an automatic fire suppression system in the fire area; or

f. Separation of cables and equipment and associated non-safety circuits of redundant trains by a noncombustible radiant energy shield.

Pursuant to 10 CFR 50.12(a), FPC requests an exemption from 10 CFR 50 Appendix R, Section III.G.2. d, e, and f. The request for exemption applies to redundant i trains of safe shutdown cables and equipment for pressurizer level, reactor l coolant system pressure, and steam generator level' in the Reactor Containment i Building on elevations 95 and 119. In lieu of the options defined in Section l III.G.2. d, e, and f, FPC proposes an alternative fire protection configuration that takes into account the special features of the CR-3 Reactor Containment Building. The proposed alternative fire protection configuration will ensure that one train of equipment necessary to achieve safe shutdown remains free of fire damage. The proposed alternate fire protection configuration will consist of:

(1) separation of cables and equipment of redundant safe shutdown trains in most locations by a horizontal distance of more than 20 feet with negligible intervening combustibles and fire hazards; and 1

(2) enclosure of one train of redundant circuits within 20 feet of the l northwest RB penetration area with 5/8" Thermo-Lag fire barriers; and (3) routing cables for redundant safe shutdown instrument strings in conduit (steel or black iron); and (4) use of IEEE 383 rated cables with EPR/hypalon thermoset material for insulation and jacket, which remains free of fire damage well beyond the fire barrier endurance rating temperature specified in Generic Letter 86-10 Supplement 1; and

U. S. Nuclear Regulatory Commission 3F.0296-26 Page 5 of 14 (5) partial area fire detection consisting of thermal fire detection in the cable tray system in both fire areas and in the vicinity of the Reactor Coolant Pumps which alarms in the CR-3 Control Room.

The enclosed detailed analysis of this alternative configuration shows that under the specific circumstances in these fire areas, the public health and safety goals of Appendix R are met.

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4. Satisfaction of Exemption Criteria Exemptions from the NRC's requirements are authorized by 10 CFR Section 50.12.

An exemption will be granted if it is authorized by law, will not present an undue risk to the public health and safety, is consistent with the common defense and security, and is supported by one or more of the special circumstances in 10 CFR 50.12(a)(2). All of those criteria are satisfied here.

The exemption is authorized by law because the underlying requirement is established by an NRC rule for which an exemption may be granted under 10 CFR. 50.12. The following evaluation of safety significance shows that the exemption will not result in undue risk to the public health and safety because an adequate level of fire protection is maintained. Common defense and security are not implicated because the equipment in question is unrelated to safeguards. Thus, the criteria in 10 CFR Section 50.12(a)(1) are met.

One of the special circumstances recognized by the Commission, as identified in 10 CFR 50.12(a)(2)(ii), is applicable here. Strict application of the rule in this situation is not necessary to achieve the underlying purpose of the rule.

Compliance with the specific requirements of Appendix R III.G.2. d, e, or f would not improve the protection for safe shutdown equipment from damage due to a realistically expected fire over the protection that exists. As the safety evaluation shows, the specific circumstances, including the presence of additional fire protection features, would not be measurably improved by strict application of the rule.

For these reasons, the NRC's criteria for issuance of this exemption are amply satisfied and the exemption should be granted.

5. General Information on Fire Protection Systems at CR-3 Fire Protection has been provided at CR-3 using a " defense-in-depth" philosophy.

The obpctives are (1) to prevent fires from starting, (2) to rapidly detect and suppress those fires which do occur, while limiting their damage, and (3) to design plant systems such that essential plant functions will not be damaged from the effects of fires.

Administrative Contrgh Since the RB is unoccupied during power operation, and only limited entries are allowed, the principal means of limiting fire hazards is by limiting the materials allowed to remain in the building and assuring equipment and systems are returned to 'as designed' status following maintenance. This control is enforced by the performance of two procedures. Prior to plant start-up following a major outage at cold shutdown conditions, Administrative Instruction AI-1305,

" Administrative Inspection of Reactor Containment" is performed. Following any outage or reactor containment entry for maintenance or inspection, Surveillance Procedure, SP-324, " Containment Inspection" is performed.

. U. S. Nuclear Regulatory Commission SF0296-26 Page 6 of 14 AI-1305 inspections are performed by designated plant managers who execute detailed walkdowns of assigned areas following specific instructions and cb M "ists. Managers are assigned areas by procedure, according to their ewrtise and functional responsibilities. In general, all inspectors have responsibility for inspecting areas for housekeeping and for ensuring equipment, piping, insulation, valves, pumps, cable trays, wiring, etc., are in good working condition. A specific checklist for fire protection includes instructions for fire detection systems, transient combustibles, and fire fighting equipment.

Other checklists include Reactor Coolant Pump oil collection enclosures and collection aanks inspections. A specific acceptance criterion in the procedure is that "All transient combustible material will be removed from Reactor Containnient. "

SP-324 is designed to confirm, in part, that no loose materials or debris are present in the containment that could be carried to the RB sump. To perform this inspection, the plant operations staff walks down all RB levels inside and outside of the secondary shield walls prior to ascending to power following an outage. When RB entries are made at power, limited inspections are performed and documented for the areas that were occupied ,. ssure that nothing was left in the work areas or pathways. The inspv tars 1 i for plastics, wood, tools, or other materials that could interfere with the capability to recirculate water from the sump. This criterion effectively eliminates materials that may also be considered transient combustibles. Our experience with these two procedures show that together, they effectively establish safe conditions in the RB and assure that they are maintained during operation.

6. Cables and EauiDment for Which an Exemption is Recuested I The cables and equipment for which an exemption is sought are located in the Reactor Containment Building. This exemption covers cables for Reactor Coolant System (RCS) and Steam Generator (SG) instrumentation. Specifically the circuits are associated with the following functions:

Pressurizer Level i RCS Pressure l Steam Generator Level l i

The primary .nstruments and transmitters for these signals are separated by more than 20 feet with negligible intervening combustibles, however, signal cables are not separated by 20 feet in all areas as discussed in the following paragraphs.

l Instrumentation differs from equipment such as pumps or power sources in that each train of instruments may be composed of many redundant individual instruments measuring the same parameter. Also, since no power sources for any of the instruments are threatened by a ii.e within the RB, instruments of the same train may be considered to be redundant to each other. This offers multiple combinations of redundancy providing high assurance of the survival of sufficient instrumentation for safe shutdown.

7. REACT 6R CONTAINMENT BUILDING FIRE AREAS RB-95-301 and RB-119-302 l

Locat. ion and Construction l Fire Areas RB-95-301 and RB-119-302 are the lowest two levels of the RB located outst of the biological or secondary shield walls. The areas are shown in rigees 1 and 2. The secondary shield wall is a four foot thick concrete wall

U. S. Nuclear Regulatory Commission 3F0296-26 Page 7 of 14 with unsealed penetrations. The only combustible material that is in the vicinity of the penetrations or passing through them is IEEE 383 rated cable.

The thickness of the wall and the lack of combustible materials provides significant resistance to fire propagation. The inner liner of the containment building is welded steel construction inside a reinforced concrete shell. The ceiling / Poor that separates the two areas is constr%ted of reinforced concrete and has numerous unsealed penetrations. This ceiling / floor is not credited as a rated three hour fire barrier. i l

Fire Protection Eauioment These fire areas are equipped with thermal line type heat detectors which are located within cable trays in both areas and which alarm in the Control Room.  :

Fire suppression equipment in the area consists of a Class III Standpipe system. l The RB standpipe system can uUlize both 1 1/2" and 21/2" hoses. Dedicated j hoses are staged at the RB per: onel hatch fee manual suppression inside. l 1

Layout and Contents of Fire Area RB-95-301 l The layout of this fire area h shown on Figure 1. It encompasses the space within the reactor containment > Iding outside the secondary shield wall, above elevation 95 and below the floor at elevation 119. One room in the area extends 1 above the 119 elevation. It is located in the northeast quadrant of the area, '

but is not open to the elevation above. Figure 1 shows the reactor coolant drain room in the northwest quadrant of the building adjacent to the secondary shield wall. This is shaped similar to the core flood tank room on the elevation above, however they are separated by the 119 elevation floor.

J The area inside the secondary shield wall contains the reactor vessel, the once through steam generators, the pressurizer, the 4 reactor coolant pumps, and the i reactor coolant pump oil collection tanks. There are some unsealed penetrations l at floor level, but these would not be paths for fire propagation. The only ;

combustible that could be present at this level inside the shield wall is reactor  ;

coolant pump oil leakage that may have bypassed the oil collection system (which i is anticipated to be minor.) Significant quantities of oil are not expected to j accumulate at this level because most of the oil reaching the floor would be drained away to the RB sump by floor drains. i A fire occurring at or near a reactor coolant pump would not damage safe shutdown circuits or equipment. One train of reactor coolant temperature instruments and all of the pressure and level transmitters and circuits are located outside of the secondary shield wall. Some pressurizer level temperature compensation circuits are located within the shield wall, but they are roded approximately 15 feet from the nearest reactor coolant pump motor and are shielded by the pressurizer vessel . The threat of a significant reactor coolant pump motor oil fire is small since only minor amounts of oil can bypass the oil collection system, and reflective insulation is used on hot piping in the area. As stated in NRC Information Notice 94-58, reflective insulation would prevent oil from coming in contact with, and igniting on, the high temperature piping it insulates. If a fire were to occur, it would be small with limited potential for damage.

Fire area RB-95-301 contains 44,802 pounds of cable, 332 pounds of Thermo-Lag, and 60 pounds of plastics. (Note that for conservatism the total amount of Thermo-Lag in these fire areas has been included as a combustible.) The cable is IEEE 383 rated cable with demonstrated resistance to ignition and fire

U. S. Nuclear Regulatory Commission 3F0296-26 Page 8 of 14 propagation. It is a design objective at CR-3 to use only IEEE 383 rated cable in all applications. When special applications have prevented the use of this cable, the specific cables are routed in conduit. Transient combustibles are strictly limited during power operation as noted above. There is a possibility that oil leakage bypassing the reactor coolant pump oil collection system can collect in the RB sump. The sump is open to this area through its cover grate, however oil collected in the sump would be floating on the surface of the water in the sump and is not considered an ignition threat.

There are a limited number of possible ignition sources b this fire area. As discussed below, most are not realistic concerns:

AHF-1B & IC Reactor building cooling fans. These are driven by 480VAC 3 phase motors with the fan and motor enclosed within a heavy gage steel enclosure.

AHF-4A & 4B Steam generator cooling fans. These are driven by 480VAC 3 phase motors with the fan and motor enclosed within a heavy gage steel enclosure.

WDP-2A & 2B Reactor building sump pumps. These are submersible pump and motor combinations which are sealed and do not represent a threat as an ignition source.

WDP-7 & 8 Reactor coolant drain tank pumps. These small pumps and motors are located within a concrete walled room with a labyrinth entry way designed to shield the reactor coolant drain tank. There are insignificant combustibles in this room and due to the design of the entry there is no possibility that these motors would be a credible ignition source for combustibles in the larger area.

Lavout and Contents of Fire Area RB-119-302 The layout of this fire area is shown on Figure 2. It encompasses the space within the reactor containment building, outside the secondary shield wall, above elevation 119 and below the floor at elevation 160. There is no floor at this elevation within the secondary shield wall.

Fire area RB-119-302 contains 43,531 pounds of cable and 1731 pounds of Thermo-Lag. The cable is IEEE 383 rated cable with demonstrated resistance to ignition and fire propagation. (See additional information above on use of IEEE 383 cable.) Transient combustibles are strictly controlled during power operation as noted above. Reactor coolant pump oil is added to the pumps periodically from stations located in this area. No more than 15 gallons of oil is taken in at a time, it is constantly attended while oil addition is proceeding, and none is allowed to remain when personnel leave.

There are a limited number of possible ignition sources in this fire area. As discussed below most are not realistic concerns:

AHF-1A Reactor buiMmg cooling fan. This is driven by a 480VAC 3 phase motor with the fan and motor enclosed within a heavy gage steel enclosure.

V. S. Nuclear Regulatory Commission 3F0296-26 Page 9 of 14 AHF-2A & 2B Reactor cavity cooling fans. These are driven by 480VAC 3 phase motors with the fan and motor enclosed within a heavy gage steel enclosure.

AHF-3A & 3B Reactor building air supply fans. These are driven by 480VAC 3 phase motors with the fan and motor enclosed within a heavy gage steel enclosure.

RCDP-1 = 7 Pressurizer heater breaker panels. These are 480VAC breaker panels which supply power to the pressurizer heaters. These panels are mounted on a raised platform eight feet above the 119 elevation floor. Safe shutdown cables for one RCS pressure instrument is routed below the platform, and cables for three 'A' SG level instruments are routed high above these panels.

Confiauration of Safety Trains The following information describes the layout of safe shutdown instruments and circuits inside the RB. It also illustrates the high level of redundancy that exists in the capability to monitor RCS and SG parameters during post fire safe shutdown. Figures I and 2 depict the circuit routings for the various instrument functions. These are not exact routings, but rather show the general paths of the various circuits between the signal trar..mitters and their containment penetrations. As noted, below most of the safe shutdown circuits are routed in rigid conduit, however at the penetrations and at the transmitters, short runs of flexible steel conduit are used.

In the vicinity of the northwest penetration area Thermo-Lag encloses one train of penetration assemblies and cables. Thermo-Lag protects the circuits routed away from the penetrations for a distance of at least 20 feet from the containment wall.

Pressurizer Level There are three pressurizer 1.' vel instruments capable of providing the required level indication. The cables for all three enter the RB through the same penetration area in the northwest quadrant of the building. These circuits enter on the 119 elevation, and after a short horizontal run, turn down to the 95 elevation where they are routed to their respective instruments. The circuits for RC-1-LT1 and RC-1-LT3 are both routed in conduit and follow pai allel paths for a distance. The circuit for RC-1-LT2 is routed partially in tray and partially in conduit. The transmitter for RC-1-LT3 is mot:nted on the northwest portion of the secondary shield wall, and transmitters for RC-1-LTl and RC-1-LT2 are mounted on the northeast portion,and are separated from RC-1-LT3 by greater than 20 feet with negligible intervening combustibles. There are no credible ignition sources in this area of the 95 elevation.

RCS Pressure There are four reactor coolant system instruments capable of providing wide range pressure indication (RC-3A-PT3, RC-38-PT3, RC-158-PT, and RC-159-PT. ) The pressure transmitters for these are mounted on the outside of the secondary shield wall, with one located in each quadrant. The circuits for RC-3A-PT3, RC-38-PT3, and RC-158-PT all penetrate the RB through the northwest penetration area at the 119 elevation. The three circuits are run in conduit for a short distance

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1 U. S. Nuclear Regulatory Comrission -

3F0296-26 Page 10 of 14 on the 119 elevation, and then penetrate to the 95 elevation enroute to their respective pressure transmitters. The circuits for RC-159-PT enter the RB through the northeast penetration area on the 119 elevation and from there the circuits, routed in conduit, run west and then south. Subsequently, the conduit ,

passes down to the 95 elevation to the pressure transmitter in the southeast  !

quadrant of the secondary shield wall. The closest approach of this circuit to redundant circuits in the north half of the RB is between the core flood tank )

room and the northwest penetration area. This distance is greater than 20 feet, l however there are intervening IEEE 383 qualified cables located high overhead.

For a fire in the south half of the building, circuits for the two instruments located in the north oortion of the building would be unaffected. I Steam Generator Level  !

There are 22 SG level instruments (SP-XX-DPT or SP-XX-LTX). Half of these are for the 'A' SG located in the north end of the RB and half are for the 'B' SG in the south end. All of the SG level transmitters are mounted on the outside of the secondary shield wall at either the north or south end according to the i location of the associated SG. l All of the SG level instrument cables enter the RB through the northwest l penetration area at the 119 elevation. Cables for two of the ' A' SG instruments '

route east and north from the penetration area on the 119 elevation to the area near AHF-3A and then penetrate down to the 95 elevation. The cables then run ,

south to the transmitters on the shield wall. These are run entirely in conduit.

The remaining cables for the 'A' SG exit the penetration on the 119 elevation and immediately descend to the 95 elevation where they route east to the shield wall and terminate at their respective transmitters. Six of these circuits are run entirely in conduit; three run partially in cable tray and partially in conduit.

There are only two locations where these two groups of circuits are in close proximity. These are at the penetration area on elevation 119, and where the conduits cross near the shield wall on the 95 elevation. There are no credible ignition sources in either of these areas.

Cables for seven of the 'B' SG level instruments immediately descend from the penetration area in the northwest of the building on the 119 elevation to the 95 elevation. These run southward on the 95 elevation to the south end of the secondary shield wall where they terminate at the level transmitters. Four of i these are run entirely in conduit; three run partially in cable tray and partially in conduit. Cables for the remaining four 'B' SG instruments are routed on the 119 elevation from the penetration area to a point south of the secondary shield wall where they descend to the 95 elevation and route north for a short distance to the transmitters on the shield wall. These are run entirely in conduit.

The only areas where less than 20 feet of separation exists between the two groups of 'B' SG instruments circuits are at the penetration area and between selected instruments at the south end of the shield wall. There are no credible ignition sources in either of these areas.

Only the instruments for one SG are required for safe shutdown. The only area common to all SG level circuits in the RB is at the penetration area. There are i no ignition sources near the penetration area. The closest ignition sources would be the pressurizer heater breaker panels, however these are not a credible threat since they are located 6 feet above the penetrations and approximately 20 feet horizontally away.

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. U. S. Nuclear Regulatory Commission 3F0296-26 Page 11 of 14 If a fire were to occur in either the north half of the building or the south half, there are insufficient' combustible materials for it to propagate to the opposite end. The only combustible material available is IEEE 383 rated cable which has been tested and demonstrated to be resistant to fire propagation.

Therefore, for a fire in any location, assurance is provided that sufficient SG 1evel instrument signals would remain available to achieve safe shutdown.

Fire loadino and Calculated Fire Severity The fire loading for fire area PM5-301 is 41,282 BTUs/sq. ft. with a calculated fire duration of 0.51 hours5.902778e-4 days <br />0.0142 hours <br />8.43254e-5 weeks <br />1.94055e-5 months <br /> or 31 minutes. The fire loading for fire area RB-119-302 is calculated to be 05,310 BTUs/sq. ft. with a calculated fire duration of 0.57 hours6.597222e-4 days <br />0.0158 hours <br />9.424603e-5 weeks <br />2.16885e-5 months <br /> or 34 minutes. Calculation of fire loading and duration in the Fire Hazards Analysis is extr m ly conservative in that it assumes every cable tray is filled to at least 50%, and actual fill is used where it is greater than 50%. The combustible load is almost completely IEEE 383 qualified cable insulation, except for 60 pounds of plastics.

8. Bases and Technical Evaluation of Exemption Reauest Bases The design of the fire protection system inside the RB meets the Appendix R objective of protecting one train of safe shutdown equipment. FPC meets the Appendix R option for separation of redundant circuits and equipment by greater than 20 feet with negligible intervening combustibles in most' portions of these two fire areas. In the vicinity of the northwest penetration area, a Thermo-Lag fire barrier encloses one train of penetration assemblies and cables. Thermo-Lag protects the circuits routed away from the penetrations for a distance of at least 20 feet from the containment wall. Figures 3 and 4 are sketches slowing the approximate Thermo-Lag protection. There are no ignition sources in the vicinity of the Thermo-Lag barriers, therefore the ignition of the Thermo-Lag or damage to protected circuits is not credible.

Additionally, CR-3 has a partial automatic fire detection system installed in the RB, The system uses linear thermal detection in the cable tray system (Protect-0-Wire) and spot thermal detectors in the vicinity of the Reactor Coolant Pumps.

These alarm in the Control Room and would provide early warning to Control Room Operators to initiate fire fighting response of the Fire Brigade. The existence of automatic fire detection is in excess of the Appendix R requirements for protection inside non-inerted containments where protection is provided by a combination of separation and radiant energy shields.

The alternatives to the existing Thermo-Lag barriers in the RB include:

a) removal and replacement of barriers with radiant energy shields constructed of a non-combustible material, b) overlaying existing barriers with a non-combustible material thereby making them non-combustible radiant energy shields, or c) installation of sprinklers inside the RB.

FPC's analysis has shown that the protection provided by any of these alternatives would not be a significant imorovement over the existing protection.

4 V. S. Nuclear Regulatory Commission 3F0296-26 Page 12 of 14 However, the implementation cost of any of these alternatives would be significant. <

Technical Evaluation The design of the Thermo-Lag fire barrier system inside the RB meets the Appendix R objective of protecting one train of safe shutdown equipment hy a radiant energy shield. In reality the enclosure of one train of safe shutdown cable in a Thermo-Lag fire barrier is superior to separation of redundant cables by l radiant energy shields. In Generic Letter (GL) 86-10, Enclosure 2, Question 3.7, I acceptable radiant energy shields are described which are placed between redundant divisions so that a fire involving the cables of one division would not

degrade or ignite cables of the other division. This configuration would not provide protection from an exposure fire which could damage both divisions. The l enclosure of one division of cables such as the barriers at CR-3 would provide j protection from a fire in the other division and from an exposure fire in another  ;

location. 1 An evaluation was performed which assessed the fire endurance capability of the subject Thermo-Lag fire barriers. The evaluation was performed by the CR-3 Fire Protection Engineer using fire endurance test data from recent industry E-119

fire tests compiled in the Nuclear Energy Institute Application Guide. The evaluation compared our installations to tests of non-upgraded configurations represented in fire test numbers NEI 1-6, NEI 2-2, and TVA 6.1.4. The Mecatiss/FPC Test of December 1994 was also used for comparison. A barrier rating of between 26 and 32 minutes was established. This is essentially equivalent to the guidance for radiant energy shield fire endurance given in GL- l 86-10 of 1/2 hour. The Thermo-Lag barriers will be wrapped with a stainless l steel screen mesh which will provide additional structural integrity.

, FPC considers that the cable test data presented in NUREG/CR-55d6 (SAND 90-0696) can be used to demonstrate cable functionality for temperatures in excess of the radiant energy shield fire endurance guidance of Generic Letter 86-10 Supplement

1. While this data would not apply for cable in general, it is applicable for

low voltage, low current instrument circuits which are the subject of this

, exemption request.

The NUREG/CR-5546 test configuration applied 208 VAC between the individual ,

conductors and ground and then measured leakage current during an exposure at  !

elevated temperatures. With this configuration, either conductor to conductor or conductor to ground (supporting tray or conduit) faults would be detected.

This voltage level is higher than the operating voltage of the Thermo-Lag protected safe shutdown instrument circuits in the CR-3 RB. The protected safe shutdown circuits operate at a maximum voltage of 32 VDC, so dielectric failures of the test conductors would be expected to occur prior to these lower voltage circuits. There was no current flow in the test conductors, however the current flow in the instrument circuits is very low, 4 to 20 milliamps, so self heating i of the safe shutdown conductors would be negligible.

CR-3 cable is EPR insulated, Hypalon jacketed and similar to the BlW Bostrad cable tested in NUREG/CR-5546. This cable showed no failures below 345*C (653*F) for an exposure time of 80 minutes. Therefore it is fully ' xpected e that the CR-3 cable would remain functional for the expected exposure in the CR-3 RB.

FPC concludes that the protection for safe shutdown cables inside the CR-3 RB provided by well separated routing of the circuits, routing in conduit and I

U. S. Nuclear Regulatory Commission 3F0296-26 Page 13 of 14 enclosure of one train of redundant circuits in Thermo-Lag in the vicinity of the penetration area, is equivalent to protection which would be provided by non-combustible radiant energy shields. The relatively low combustible loading, the type of combustible material in the building, and the scarcity of ignition sources all contribute to a low probability that fire would damage safe shutdown cables.

The CR-3 Fire Hazards Analysis estimates the amounts of combustibles in fire areas RB-95-301 and RB-119-302 to be 41,033 and 43,880 BTU /sq. ft., respectively.

These are conservative estimates as noted above and the combustible material is virtually all IEEE 383 rated cable insulation. Therefore, the principal fuel source in the RB is material that is difficult to ignite.

The ignition sources listed above have a low potential for igniting the combustible materials in these two fire areas. The fan motors listed are all contained inside heavy gage steel enclosures which provide both structural support and air flow intake and distribution. If a fire were initiated in one of these motors, it would be contained within the enclosure and would not propagate to outside combustibles. The small pump motors for WDP-2A & 2B are sealed submersible motors located well away from safe shutdown circuits. The small motors for WDP-7 & 8 are located inside a concrete walled room and no safe shutdown cables are routed through the enclosure.

The pressurizer heater breaker panels, RCDP-1 through 7, contain very few internal cables to allow fire to propagate within the cabinet and the contained cables are IEEE 383 rated. These panels are not fully enclosed but have wire mesh on the front to facilitate cooling. Cables entering and exiting these panels are all run in conduit so they would not be a pathway for fire l propagation. The panels are fed from breakers outside the RB so they would '

automatically clear in the event of a short circuit, or could readily be de-energized in the event of a fire.

A fire involving the lubricating oil for the reactor coolant pump motors (RCPMs) l 1s not a threat to safe shutdown cables or equipment in the RB. The RCPMs are l located inside the secondary shield wall. Any leakage from the RCPMs will either l be contained within the RCPM oil collection system, or would be prevented from reaching the hot piping surfaces due to the use of reflective insulation. Oil which may reach the RB floo'r will either remain on the floor within the secondary shield wall, or will migrate to the RB sump. The unlikely occurrence of a fire in any of these locations will not damage safe shutdown equipment or circuits.

If a fire was to start within the RB, the huge volume of the building and the unsealed openings between floors would preclude the formation of a hot gas layer at any elevation where it would affect safe shutdown cables. Considering1)the proximity and geometry of the limited amount of fuel, 2) the equally limited number of ignition sources, and 3) the low flammability of the principal fuel source, the conditions to which safe shutdown cables will be exposed are ,

insufficient to cause anything but minor cable damage to limited numbers of '

circuits.

CR-3 has a partial automatic fire detection system installed in the RB. The system uses linear thermal detection in the cable tray system (Protect-0-Wire) and spot thermal detectors in the vicinity of the Reactor Coolant Pumps. These alann in the Control Room and would provide early warning to Control Operators to initiate fire fighting response of the Fire Brigade. The existence of automatic fire detection is in excess of the Appendix R requirements for

. U. S. Nuclear Regulatory Commission 3F0296-26 Page 14 of 14 protection inside non-inerted containments where circuit protection is provided by separation.

4

9. Conclusion FPC has Thermo-Lag fire barriers constructed at 5/8" thick material protecting one train of safe shutdown cables inside the CR-3 RB. These barriers were 4

installed in 1985 during our plant upgrade to implement Appendix R requirements.

FPC chose Thermo-Lag enclosures over traditional radiant energy shields because these were believed to provide more effective protection. Also, installation d

required less labor, therefore lower radiation exposure. These barriers were found to be acceptable to the NRC. Since that time, information on the behavior of Thermo-Lag has shown that when exposed to a significantly challenging fire Thermo-Lag will burn.

Considering the factors described above relating to the type and amount of fixed

combustibles, the absence of transient combustibles, and the limited number of e

ignition sources, it is extremely unlikely that a fire would start in any area that contains safe shutdown circuits. If a fire were to start, it would not grow to any significant size or propagate to involve more than a small localized area.

FPC has evaluated the Thermo-Lag barriers inside the CR-3 RB and considers that -

they will provide protection equivalent to non-combustible radiant energy shields. In addition, FPC has partial coverage automatic fire detection systems

in the RB to provide early warning of a fire. FPC has concluded that these

factors taken together demonstrate sufficient defense in depth to meet the intended protection of safe shutdown circuits inside the RB. These factors are deemed to be sufficient justification for an exemption to Appendix R Section j III.G.2, as equivalent to the protection provided by one of the specific options ,

of Appendix R. Therefore, this exemption should be granted.

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