ML20206D420
| ML20206D420 | |
| Person / Time | |
|---|---|
| Site: | Three Mile Island  |
| Issue date: | 04/20/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20206D405 | List: |
| References | |
| NUDOCS 9905040104 | |
| Download: ML20206D420 (22) | |
Text
o asog j p k UNITED STATES
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j NUCLEAR REGULATORY COMMISSION g WASHINGTON, D.C. enana ann,
- A5ETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION GPU NUCLEAR. INC. REQUEST FOR EXEMPTION FROM SECTION lli.G.2.c OF APPENDlX R TO 10 CFR PART 50 THREE MILE ISLAND NUCLEAR GENERATING STATION. UNIT 1 DOCKET NO 50289 Appendix R, " Fire Protection Program for Nuclear Power Facilities Operating Prior to January 1,1979," to Title 10 of the Code of Federal Reaulations (10 CFR) Part 50, establishes fire protection features required to satisfy General Design Criterion 3, " Fire protection," of Appendix A to 10 CFR Part 50,' with respect to certain generic issues for nuclear power plants licensed to operate prior to January 1,1979. TMl was licensed to operate prior to January 1, 1979, and thus, is subject to Appendix R requirements. By letter dated December 31,1996, as supplemented by letters dated September 8 and December 30,1997; May 21, October 14, November 25, and December 23,1998, GPU Nuclear, Inc., (licensee) requested an exemption for Three Mile Island Nuclear Generating Station, Unit 1 (TMI-1) from the technical requirements of Section Ill.G.2.c of Appendix R to 10 CFR 50, to the extent that they specify the separation of certain redundant safe shutdown circuits with 1-hour fire-rated barriers. This request was made for 10 fire areas / zones at TMI-1.
The licensee based its request for exemption, in part, on a cable functionality assessment it ;
performed for the cables in question. The licensee determined a cable qualification rating that it assigned to the cables based upon an extrapolation of test results from a Nuclear Energy Institute (NEI) Test Scheme 21. The licensee stated that the cable qualification rating is the fire endurance rating of the barrier when considering the cable qualification temperature or the maximum temperature inside the fire barrier envelope that is considered acceptable in demonstrating cable functionality for a specific set of installed fire barriers at TMI-1. For the i purpose of the staffs review, those fire endurance performance criteria are located in Generic l Letter 86-10, Supplement 1. The NRC staff, in conjunction with its contractor, Sandia National l Laboratories (SNL), has completed its review of the licensee's analytical approach for cable l' functionality detent.! nations. The results of the staffs review of the licensee's cable functionality assessment are documented in Part 1 of this S1fety Evaluation and the attached SNL Technical Letter Report (TLR), "A Technical Review of The GPU Nuclear Three Mile Island Unit 1 Cable Functionality Assessments," dated February 26,1998. The evaluation of ,
the licensee's specific exemption requests for the 10 fire areas / zones is contained in Part 2 of this Safety Evaluation.
1 Part 1 - Cable Functionality Assessment
1.0 INTRODUCTION
For a subset of the fire barriers at TMl-1, the licensee has performed a cable functionality analysis in order to demonstrate an estimated fire rating equivalent to the American Society for Testing and Materials (ASTM) and/or National Fire Protection Association (NFPA) fire 9905040104 990420 "
i endurance rating denoted as a ' cable qualification rating (CQR)." The CQR is based on an assessment of cable functionciity during an exposure time period beyond the time interval of the actual test for the applicable fire barrier configuration. These evaluations involve installations for which a 1-hour ASTM and/or NFPA fire endurance rating of at least 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> cannot be demonstrated by test. For these applications the licensee is requesting approval of a change from the ASTM and/or NFPA fire performance evaluation criteria based upon altamative " ratings" which were derived from the functionality assessments.
Specifically, the licensee has utilized the cable functionality approach for fire barriers in 10 specific fire areas / zones. Some of these areas / zones contain numerous individual barrier systems. All of the cable functionality evaluations are associated either with cables in conduits
- (including straight sections of conduits, radial bonds, and condulets) or with armored cables.
All of the functionality assessments have been based on the extrapolation of test results from a single fire endurance test; namely NEl Test 2-1.
The overall licensee functionality assessment process can be summarized as follows:
The 1,consee has estimated the " Cable Functionality Temperature" (CFT) for its cables to be 698'F (370'C). The licensee assumes that this value represents a reasonable bounding estimate of the thermal failure threshold of its installed cables. This value is based on the results of SNL testing of cables as referenced in the licensee's submittal of December 31,1996.
The licensee has compared its installed, non-upgraded fire barrier systems to those described in the NEl Application Guide. The licensee has concluded that the installations used in NEl Test 2-1 are representative of all of the conduit and armored cable base installations. This single NEl test is then used as the basis for all of the subsequent cable functionality evaluations.
The licensee utilized the NEl Test 2-1 data to make a direct assessment of the " actual rating" for the subject barriers. This " actual rating" is based only on the nominal single point temperature rise criteria established in the ASTM E-119 and NFPA 251 fire test standards (i.e.,325'F rise above ambient). In all cases relevant to the functionality based exemption requests, these " actual" endurance times are less than the required 1-hour rating for the TMI-1 installations. In particular, in NEl Test 2-1 the conduits exceeded the nominal temperature criteria in 27-50 minutes depending on the individual conduit.
In order to assess the cable functionality beyond the time interval of the actual rating, the licensee extrapolated the measured temperature response from NEl Test 2-1 beyond the range of actual test data. That is, NEl test 21 was terminated after a 50 minute exposure, and no temperature data beyond this time is available. Therefore, the licensee has extrapolated the test data out beyond the actual test duration to estimate what the temperature response might have been had the test been continued for a full hour.
The resulting temperature response is then compared directly to the CFT with some modification for margin factors (for plant ambient and cable temperature). Based on this comparison, the licensee determines a duration time that it defines as the " Cable
o 3-Qualification Rating" (CQR). That is, the time period at which the sctual or estimated thermal response, plus some margin factors, equals the CFT, is cited as the CQR. This represents the licensee's assessment of the estimated time threshold when installed cables would have actually reached a potential failure threshold within the context of cable functionality for the barrier configuratm l
For those cases where a CQR of 57 minutes or greater is determined, the licensee i
requests an exemption from the requirements of 10 CFR 50, Appendix R, Section Ill.G.2.c.
In each case the assessments are also supported by a discussion of the local fire hazard conditions.
The NRC staff, in conjunction with its contractor, SNL, has completed its review of the licensee's analytical approach for cable funchonality determinations. The results of the re': ew are documented in the following evaluation and attached SNL TLR.
l 2.0 EVALUATION After reviewing the licensee's submittals and the SNL TLF to staff agrees with the SNL analyses and conclusions. The cable functionality review ..tions, the licensee's responses, and the staff's evaluation of the responses follow.
2.1 Cable Functionality Questions l 1. SNL made the following finding after a review of the licensee's c.able functionality assessment method:
The licensee basis for its determination of the temperature response measured during the fire endurance tests has not been adequately established. Of particular concem to SNL in this regard is the fact that the licensee nas taken fire test data from a test that l lasted for less than one hour (i.e., 50 minutes) and has extrapolated that data to a 1-l hour exposure period using a thermal model that was not included in the submittal.
l The extrapolation of fire endurance data beyond thu actual test duration is, at best, an
- uncertain practice. Mr.ny faciors can influence the thermal response of a fire .
i endurance test, and certain of these factors may not be amenable to analysis or edi.polet;on.
Further, although Supplement 1 of GL 86-10 states that cable functionality assessments l can be made if they are " based on a comparison of the fire barrier intamal temperature
! profile measured during the fire endurance test to existing cable specific performance data," J9mative methodologies can be used provided that the technical basis can be established for the assessment of the thermal exposure conditions.
Given the above finding the licensee is requested to provide the supporting document, Calculation C-9000-814-5310-002 and a detailed explanation of both the uncertainties and conservatiems in these extrapolations. Specifically, the licensee should address the following points:
4 How has the analysis treated the potential for material bum-through in extrapolating the NEl test data assessment?
On what basis has the licensee thermal extrapolation model been validated?
Documentation of the extrapolation model should be in detail so as to allow independent implementation and verification. The licensee is requested to provide the coiresponding validation results and studies for staff review.
Licensee Response in its submittal dated December 30,1997, the licensee provided the subject calculation for staff review. In addition, the licensee also discussed the basis and validation of its thermal extrapolation model including the issue of material bum through. On the issue of material bum-through, the licensee cites two arguments to discount occurrence during the extrapolation period: (1) No evidence fro. : the NEl Test 2-1 temperature data, post exposure test obsentations or from extrapolated Thermo Lag barrier temperatures suggest a barrior bum-through during the extrapolation period (i.e., 50 - 60 minutes), and (2) NEl Test 1-6, which was similar to NEl Test 2-1, survived for the full 60-minute period with an absence of bum-through observed; therefore, by implication bum-through would have not occurred during the j extrapolated time period for Test 2-1.
Staff Evaluation As noted in the SNL TLR, there are sp tcific weaknesses in the licensee's extrapolations of the thermal performance of NEl Test 2-1 fu the time period beyond actual test performance.
Given that affirmative data was not prov.ded and industry test data indicates that bum-through usually occurs in the last minutes of the fire endurance test for marginal fire barrier configurations the staff cannot support the licensee's assertion regarding NEl Test 2-1 in the extrapolated time period.
- 2. Many of the fire banier tests performed by the industry have failed due to bum-through.
SNL would consider bum-through to be a case where the virgin Thermo-lag barrier material is fully consumed at any given location during the test leaving only a fragile char layer visible. It appears that the NEl tests were evaluated using a different interpretation of bum-through.
Specifically, SNL makes the following observations:
SNL has reviewed the documentation for NEl test 2-1 as presented in the NEl Application Guide. Particularly troubling to SNL are certain passages included in the post test inspechons of the test articles. The licensee applications involve 2" or larger conduits; hence, only the corresponding 2" and larger test results are of direct interest. Consider for example the description for the 2" conduit. The NEl/ Omega Point Laboratories (OPL) test report cites the following:'
'See page 14 of the OPL/NUMAfiC Fleport No. 13890-96141 as presented in Appendix 1 of the NEl Application Guide.
l 5-For the vertical section: "Several araas having 0 in. uncharred material remaining."
for the horizontal section "Several areas in section having 0 in. uncharred material remaining."
Similar descriptions are given for the 4" and 6" conduits as well, particularly in the case of each horizontal section. This condition is not described as a " bum-through" in the report, but it is unclear how NEl/OPL defined a " bum-through." SNL finds that this physical description is a clear indication that bum-through was, at the very least, imminent at the time of test termination. Once the virgin Thermo-Lag has been consumed and there is no remaining uncharred material, bum-through is all but inevitable unless the test is stopped.
' The statements of no remaining virgin materialin "several areas" raises troubling questions for the TMI-i analysis and in particular the validity of any data extrapolations.
Thermo-Lag 330-1 material is supposed to derive its primary fire protective ability through sublimation (direct solid-to-gaseous phase transition) and intumescent (the swelling and formation of a char layer as a result of the combustion process) behavior. Once the virgin material has been consumed, the only protective mechanism left active is the modest I
insulating power of the char layer. The charred material is relatively fragile, and may be dislodged from the cables during fire exposure. Unlike the virgin material, the char layer is porous and significant heat transfer through the char layer would be expected with the rate of temperature rise experiencing a sudden increase. Therefore, an understanding of bum-through behavior is critical for predicting the ultimate thermal response of the protected commodity to the exposure fire.
The licensee was requested to discuss the post-test physical inspection results for the relevant test items from the NEl test report and specifically to address the implications of the statements such as "several areas having 0 inches of uncharred material remaining" 4 with regards to the application of the NEl test results for extrapol.stion purposes such that I the subject cables will be able to continue to function during the full 1-hour period. I Licensee Response in its submittal dated December 30,1997, the licensee reiterated its arguments discounting bum-through as cited in the response to Question 1 and stated that observations such as 0 inches of unbumed material remairang are not indicative of a bum-through but the presence of a char layer. The licensee stated that the char layer was an important factor in fire barrier performance.
Staff Evaluation The licensee's response regarding the occurrence of bum-through does not resolve staff concems in this area for the reasons stated in Question 1.
- 3. SNL noted that the licensee's cable functionality assessments as contained in the December 31,1996, submittal require ariditionel clarification or justification in the following areas:
l 1
- a. SNL found that the licensee submittal has not established an adequate basis for the assumed cable damage or failure threshold. SNL does not question the acceptability of the cited NUREG/CR test results in general, but rather, the applicability of the cited result to the licensee's cables. The licensee is requested to provide the cited GPUN memo 5350-95-063 for review along with any supporting documentation.
- b. SNL found that the licensee has not established an adequate basis for the assessment of individual circuit performance requirements. While the cited cable performance results are appropriate for low-to-medium voltage power and control applications, they may not be appropriate for higher voltage power nor instrument circuits. The licensee is requested to: (1) identify each of the analyzed circuits as either power, control, or
- instrumentation along with the corresponding voltage and ampacity loads for all pov er 1 cables; and (2) provide an assessment of circuit performance requirements for both a limiting voltage power cable application and for a limiting instrumentation case. This assessment should ir.clude a direct link between circuit functionality requirements and the cited damage threshold.
- c. SNL found that the licensee analyses have not adequately addressed the issue of power cable self-heating effects, and in particular, that the cited cable performance tests upon which the cited functionality limits are based have ngj bounded this effect.
Hence, the submittal is deficient in this regard.
Specifically, SNL makes the following observations:
SNL finds that the licensee inclusion of an additional 7'F increment to allow for cable self-heating effects is not adequate to address the concem. It would appear that the licensee is attempting to address self-heating effects by simply incrementing the 1 ambient exposure to reflect the ambient temperature within the fire barrier. The specific j question is what is the additional temperature increment between the cable itself and the ambient temperature at the onset of the fire, not what is the temperature of air immediately around the cable. A second factor to be considered is the fact that the J
cited licensee documents (
Reference:
Letter from J. Brendien to J. W. Langenbach, l "TSI Derating Check,'G/C/TMI-1CS/16503 dated September 15,1988) supporting this l value were reviewed separately as a part of the licensee ampacity assessments. As a !
result of this separate review, the licensee has agreed that the cited tests were not of i adequate quality to be used in the context of the regulatory process, and hence, has i withdrawn their reliance on those results for ampacity dorating process. The exact same objections would apply in this application. in particular, the licensee has not demonstrated an adequate level of quality assurance for these tests, nor has the licensee demonstrated that the cited tests actually measured a limiting case for the electrical raceways installed in TMI-1.
As noted by the licensee on page 11 of the Topical Report #094 attached to the licensee's submittal, the SNL test cited as the basis for the licensee assumed cable damage limits did involve an imposed voltage potential, but did not involve imposed current flows during the tests. It is not correct to infer that cable self-heating is bounded by tests such as those performed by SNL.
Therefore, the licensee assessments should independently allow for the ohmic effect for energized power cables.
l The licensee is requested to: (1) identify each of the barrier envelopes that includes i
power cables within the protected envelope; (2) for each power cable circuit, determine whether or not it is reasonable to postulate that the circuit might be energized at the outset of a fire; (3) for all energized power cables assess the temperature increment that characterizes the rise in temperature of the cable above the surrounding ambient temperature due to ohmic heating effects consistent with the licensee's own ampacity assessments; and (4) for each impacted envelope explicitly include the power cable self-
) heating effect in the functionality assessment including consideration of the mutual heating effect for collocated but non-energized cables.
- d. As a final point of note, the licensee has apparently assumed that an equivalent cable qualification rating of *at least 57 minutes"is sufficient to meet the intent of the '
l Appendix R requirement for a 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> barrier system. The licensee is requested to l provide justification for the above assumption.
Licensee Response In its submittal dated December 30,1997, the licensee provided the following response:
3.a The cited memorandum was provided by the licensee.
3.b. The licensee stated that there are no instrumentation circuits impacted by the exemption request. The licensee contends that the damage thresholds l
which are applicable to control and power cables ranging from 600 - 5000 volts were consistent with the referenced SNL test findings.
3.c. The licensee provided the updated calculations which include appropriate I
consideration of ampacity limits, actual cable loads and ambient temperatures.
l 3.d. The licensee has performed an analysis demonstrating the adequacy of a 57-minute fire rating based upon its fire hazards analysis.
l Staff Evaluation The information provided by the licensee fully resolves the staff's concems.
2.2 Acceptability of Cable Functionality Analytical Methodoloav l 1
\
The licensee functionality assessments are dependent on the simulation of the expected l thermal environment for NEl Test 2-1 extended beyond the period of actual test performance.
l SNL identified the following specific technical wealmesses in the licensee calculations: (1) An inappropriate application of thermal conductance values for larger conduits to the simulation of j smaller conduit thermal response; (2) An inappropriate application of thermal conductance j values from an upgraded barrier system to the simulation of a non-upgraded barrier; and (3) l l
l
8-An optimistic treatment of the conduit to cable heat transfer, Given the inherent uncertainties involved with predicting the thermal response of marginally acceptable fire barriers the staff finds that items 1 and 2 can only be resolved through the validation of model parameters against actual test data.
On the question of whether material bum-through would have occurred beyond the performance period (e.g., greater than 50-minute period for 2-inch conduits in NEl Test 2-1) the staff's experience v*h the Texas Utilities Electric (TUE) and Tennessee Valley Authority .
(TVA) fire endurance test programs reinforces the arguments presented by SNL (see attachment) that material bum-through represents a potential safety concem. The licensee's assertion that the absence of bum-through in NEl Test 14 implies evidence that NEl Test 2-1 would not experience bum-through clearty discounts the significance of the structural upgrades which is the difference between the two test configurations. Both the TVA and TUE test programs clearly demonstrate tne fact that structural upgrades can mean the difference between a successful or failed test. Further, the absence of indications of bum-through in one test configuration does not constitute evidence regarding the performance of a different test configuration it should be noted that the licensee submittals have provided a technical basis to take credit for the " actual rating" of NEl Test 2-1 raceway configurations (i.e. equivalent ratings within the tested time period) provided that the TMl-1 installed raceway configurations are representative in construction and design of their NEl Test 2-1 counterparts.
3.0 CONCLUSION
S On the basis of the above evaluation, the staff concludes that the specific set of fire barriers have not demonstrated adequate basis to meet the cable functionality requirements as specified in GL 86-10, Supplement 1 using the licensee's analytical methodology, nor have they proposed an acceptable altemative. However, the licensee has demonstrated a technical basis for a fire rating period equivalent to the time period prior to temperature criteria exceedance (denoted " actual rating" by the licensee) for the tested NEl Test Scheme 2-1 provided that the installed fire barriers are representative of the construction and design of the subject NEl test specimen.
Part 2 - Staff Evaluation of Specific Exemption Ree==**
1.0 INTRODUCTION
Appendix R, " Fire Protection Program for Nuclear Power Facilities Operating Prior to January 1,1979," to Title 10 of the Code of Federal Reaulations (10 CFR) Part 50, establishes fire protection features required to satisfy General Design Criterion 3, " Fire protection," of Appendix A to 10 CFR Part 50, with respect to certain generic issues for nuclear power plants licensed to operate prior to January 1,1979. By letter dated December 31,1996, as supplemented by letters dated September 8,1997, December 30,1997, May 21,1998, October 14,1998, November 25,1998, and December 23,1998, GPU Nuclear, Inc., the licensee for TMI-1 requested an exemption from the technical requirements of Section Ill.G.2.c of Appendix R to 10 CFR, Part 50, to the extent that it specifies the separation of certain redundant safe shutdown circuits with 1-hour fire-rated barriers.
s 9
2.0 DISCUSSION The licensee's request encompasses ten fire zones / areas where Thermo-Lag is installed on electncal raceways and was originally installed to provide 1-hour separation between redundant circuits located in the same fire area in accordance with Sechon Ill.G.2.c of Appendix R. In a letter of December 31,1996, the licenses presented information which indicated that the Thermo-Lag envelopes in the zones / areas mentioned below have actual fire endurance ratmos of less than 1-hour.
The licensee has requested the exemption for the following fire areas / zones:
AB-FZ-3, AB-FZ-4, AB-FZ-5, AB-FZ-7, CB-FA-1, FH-FZ-1, FH-FZ-2, FH-FZ-6, ISPH-FZ-1, ISPH-FZ-2.
The licensee has administrative controls in place over transient combustibles and work in the plant in accordance with 10 CFR Part 50 Part Appendix R, items Ill.K, items 1-8, as discussed !
in an NRC safety evaluation dated June 4,1984. These controls require total in situ plus allowable transient fire load in a fire area / zone (or cumulative load) to be half of that which would challenge the lowest rated barrier in the zone based on equivalent fire severity. These limits are documented in licensee procedures that are referenced in, and implement, the licensee's Fire Protection Program under license condition 2.c(4).
The licensee completed an evaluation of all the Thermo-Lag fire barriers which are subject in I this exemption request in Topical Report #094, Revision 2, "TMl 1 Evaluation of Thermo-Lag Fire Barriers," dated December 20,1996, provided in a letter dated December 31,1996. The licensee found that most of the barriers currently have a fire rat:ng of loss than 1-hour (when tested in accordance with the American Socoty for Testing and Materials (ASTM) E-119 fire test standard). In addition, in a letter dated November 25,1998, the licensee committed to inspect all the material and seams on each Thermo Lag fire barrier installed at TMI Unit 1.
This inspection will resolve the deficiencies in the Thermo-Lag barriers reported by the licensee in several 10 CFR 50.72 and 10 CFR 50.73 reports submitted in August, September, and October 1998. In each of the areas / zones where automatic suppression and/or auttmatic detection is provided, the systems installed in the plant meet all applicable NFPA codes, specifically the enteria for a Class 1 detection specified in NFPA 72D and NFPA 13 or NFPA 15 for suppression systems. A summary of the physicallayout, fire hazards, fire protection features, and protected circuits for each of the 10 fire areas / zones is presented below.
2.1 Fire Area AB-FZ-3 Thir, area is located on elevations 281 and 295 of the auxiliary building and measures a0 proximately 40 feet x 7 feet x 23 feet high. The principal combustibles in the area are
' exposed cable insulation. Most of the cable insulation in the area meets the Institute of Electncil and Electronics Engineers (IEEE) 383 standard for flammability. The fire loading in this area is low. This area is a high radiation area, and therefore is not normally occupied. A concrete ceiling at the 295 elevation separates the Thermo-Lag envelope from the rest of the fire zone.
Fire protection features for this zone include a zone-wide ionization smoke detection system
- which actuates an alarm in the control room A fire hose station is available in an adjacent fire zone. It is estimated by the licensee that the full fire brigade complement could bring manual .
suppression to bear on a fire in this fire area in 15 minutes. An exemption was previously granted by the NRC from the requirement for a zone-wide fire suppression system.
The specific safe shutdown circuit and equipment protected by the existing Thermo-Lag fire barriers in this fire area are associated with the following function:
e Make-up Suppo-ting Funchon This function requires fire banier protection in order to insure a safe shutdown path is available if a fire damages the redundant unprotected circuits and equipment in this fire area. Cables for the above functions are protected in one fire barrier envelope protecting a 2-inch conduit.
The envelope is not located near in situ combustibles or ignition sources. The actual fire endurance rating for this envelope is 39 minutes, as determined in a fire endurance test conc ucted in accordance with ASTM E-119.
2.2 Fire Zone AB-FZ-4
- This zone is located on elevation 281 of the auxiliary building and measures approximately 45 feet x 30 feet x 23 feet high. The principal combustible in the area is exposed cable insulation. Most of the cable insulation in the area meets the IEEE 383 standard for flammability. The fire loading for this area is considered to be low.
Fire protection features for this zone include an automatic pre-action sprinkier system and a hose station, as well as a zone-wide ionization smoke detection system which actuates an alarm in the control room. A fire hose station is available in an adjacent fire zone as well, and is capable of bringing a hose stream to bear on any location within this fire area. It is estimated by the licensee that the full fire brigade complement could bring manual suppression 3 to bear on a fire in this fire area in 15 minutes. '
The specific safe shutdown circuits and equipment protected by the existing Thermo-Lag fire barriers in this fire area are associated with the following functions- i i
e Reactor Coolant Pump (RCP) Seal Injection e Nuclear Services River Water (RCP Thermal Barrier Cooling)
These circuits require fire barrier protectiori in order to insure a safe shutdown path is available if a fire damages the other unprotected circuits and equipment in this fire area. Cables for the above functions are protected in three different banier envelopes of 2-inch conduit. The actual ,
fire endurance rating for these envelopes is 39 minutes as determined in a fire endurance test '
conducted in accordance with ASTM E-119.
2.3 Fire Zone AB-FZ-5 This zone is located on elevation 281 of the auxiliary building and measures approximately 110 feet x 160 feet x 23 feet high. The principal combustible in the area is exposed cable
p i
i 11 insulation. Most of the cable insulation in the area meets the IEEE 383 standard for flammability. The fire loading for this area is considered to be low. 1 Fire protechon features for this zone include an ionization smoke detechon system (which t
actuates an alarm in the control room) in the immediate vicinity of the Thermo-Lag envelopes, but not zone wide, as well as a hose station and a dry chemical fire extinguisher. A fire hose l stabon is avtilable in an adjacent fire zone as well. It is estimated by the licensee that the full fire brigade complement could bring manual suppression to bear on a fire in this fire area in 15 minutes. An exemption was previously granted by the NRC from the requirements for zone-wide fire suppression and zone-wide smoke detection systems.
The specific safe shutdown circuits and equipment protected by the existing Thermo-Lag fire barriers in this fire area are associated with the followmg functions:
l e Make-up Supporting Function e Make-up (Inventory)
These circuits require fire barrier protechon in order to insure a letdown cooling, adequate minimum recirculation flow for make-up, and a controllable valve to prevent contents of the Borated Water Storage Tank (BWST) from draining to the reactor building sump during hot shutdown, Cables for the above fun tions are protected in two different barrier envelopes of 2-inch and 2.5-inch conduit. The actual fire endurance rating for these envelopes is 39 minutes as determined in a fire endurance test conducted in accordance with ASTM E-119.
2.4 Fire Zone AB-FZ-7 l This zone is located on elevation 305 of the auxiliary building and measures approximately 3 i
64 feet x 20 feet x 20 feet high. The principal combustibles in the area are pump lobe oil l (approximately one quart per pump) and exposed cable insulation. Most of the cable insulation in the area meets the IEEE 383 standard for flammability. The fire loading for this area is considered to be low.
Fire piei.ct;0n features for this area include an ionization smoke detochon system which actuates an alarm in the control room and cross zoned ionization smoke detection which actuates an automatic pre-action spnnkler system to provide a water curtain for an open passageway to an adjacent fire area. A fire hose station is available in an adjacent fire zone as well as a dry chemical and CO, fire extinguisher. It is estimated by the licensee that the full fire brigade complement could bring manual suppression to bear on a fire in this fire area in 15 minutes. An exemption was previously granted by the NRC from the requirement for an area-wide fire suppression.
The speafic safe shutdown circuit protected by the existing Thermo-Lag fire barriers in this fire area is associated with the following function:
e Make-up Supporting Function (Nuclear Services Closed Cooling Water)
This function requires fire barrier protection in order to insure availability of at least one Nuclear Services Closed Couling Water pump by protecting two or three circuits. Cables for l
l
r i the above functions are protected in two different barrier envelopes of 2-inch conduit and armor cable and 3-inch and 4-inch conduit. There are no in situ combustibles near these envelopes. The actual fire endurance rating for these envelopes is 50 minutes for the 4-inch conduit and 39 minutes for all the others as determined in a fire endurance test conducted in accordance with ASTM E-119.
2.5 Fire Area CB-FA-1 This area is located on elevation 306 of the control building and measures approximately 100 feet x 60 feet x 15 feet high. The principal combustibles in the area are exposed cable insulation and transients typically consisting of rope, signs, radiation control support equipment, safety carts which contain emergency support equipment and ladders. In addition, there is one %-inch diameter acetylene gas line above the suspended ceiling running from an outdoor tanh through a pressure regulator and manualisolation valve to an indoor chemical lab. Most of the cable insulation in the area meets the IEEE 383 standard for flammability.
The fire loading for this area is considered moderate.
Fire protection features for this area include an automatic wet pipe sprinkler system which is located below the suspended ceiling in the area. Area-wide ionization detection which actuates an alarm in the control room is provided above the suspended ceiling. In a letter dated October 14,1998, and supplemented December 23,1998, the licensee committed to install combustible gas detectors in this fire area to detect and provide prompt notification in the event of an acetylene leak. In addition, a portable dry chemical extinguisher is available in the adjacent fire zone. it is estimated by the licensee that the full fire brigade complement could bring manual suppression to bear on a fire in this fire area in 15 minutes. An exemption was previously granted by the NRC from the requirement for an area-wide fire suppression system above the suspended ceiling in this zone.
The specific safe shutdown circuits and equipment protected by the existing Thermo-Lag fire barriers in this fire area are associated with the following functions:
- Make-up and Supporting Functions e RCS Pressure o Reactor Coolant Pump Thermal Barrier Cooling
- Nuclear Services Closed Cycle Cooling e Decay Heat Closed Cycle Cooling e Electrical Power System These circuits require fire barrier protection in order to insure a safe shutdown path is available if a f'"e damages the other unprotected circuits and equipment in this fire area. Cables for the abow functions are protected in 18 different fire barrier envelopes which contain 2-inch, 2.5-inch,3-inch,3.5-inch,4-inch and 5-inch conduit and 2-inch,2.5-inch, and 3-inch armor cable protected by Thermo-Lag. The envelopes have an actual fire endurance rating of 50 minutes for the 4-inch and 5-inch conduit and 39 minutes for all others as determined in a fire endurance test conducted in accordance with ASTM E-119. The envelopes all run above the suspended ceiling.
1
2.6 Fire Zone FH-FZ-1 This zone is located on elevstion 281 of the fuel handling building and measures approximately 54 feet x 144 feet x 23 feet high. The principal combustibles in the area are exposed cable insulation and transients (as described above). Most of the cable insulation in the stea meets the IEEE 383 standard for flammability. The fire loading for this area is considered low.-
Fire protechon features for this zone include an automatic wet pipe sprinkler system which protects the entire floor with sprinkler heads located above, below, and in between cable trays on elevation 281. lonization smoke detection which actuates an alarm in the control room is provided as well as a fire hose station, in addition, a portable dry chemical extinguisher and an additional hose station are available in an adjacent fire zone. It is estimated by the licensee that the full fire brigade complement could bring i tanual suppression to bear on a fire in this fire area in 15 minutes.
The specific safe shutdown circuits and equipment protected by the existing Thermo-Lag fire barriers in this fire area are associated with the following functions:
e Make-up and Supporting Functions e RCS Pressure e Reactor Coolant Pump Thermal Banier Cooling
- Nuclear Services River Water e Decay Heat River Water o Electncal Power System These circuits require fire barrier protectisn in order to insuce a safe shutdown path is available if a fire eliminates all other unprotected circuits and equipment in this fire zone. Cables for the above functions are protected in six different fire barrier envelopes which contain 3 inch and 4-inch conduit and 2.5-inch,3-inch, and 4-inch armor cable protected by Thermo-Lag. The envelopes have an actual fire endurance rating of 50 minutes for the 4-inch conduit and 39 minutes for all others as determined in a fire endurance test conducted in accordance with ASTM E-119.
2.7 Fire Zone FH-FZ-2 This zone is located on elevation 305 and 306 of the fuel handling building and measures approximately 150 feet x 50 feet x 21 feet high. The principal combustibles in the area are exposed cable insulation and transients. Most of the cable insulation in the area meets the IEEE 383 standard for flammability. The fire leading for this area is considered low.
Fire protechon features for this zone include an automatic wet pipe sprinkler system on elevation 306 adjacent to the control building. CO 2and dry chemical extinguishers are available in the fire zone, as well as in adjacent zones. A hose station is available immediately l outside the north wall of the zone, as well as in adjacent zones. It is estimated by the licensee that the full fire brigade complement could bring manual suppression to bear on a fire in this fire area in 15 minutes. Smoke detection is not provided in this zone. An exemption was ,
previously granted by the NRC from the requirement for a zone-wide fire detection system. j c
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The specific safe shutdown circuits and equipment protected by the existing Thermo-Lag fire baniers in this fire area are associated with the following functions:
e Make-up and Supporting Functions e Decay Heat e Reactor Coolant Pump Thermal Barrier Cooling These circuits require fire barrier protection in order to insure adequate minimum recirculation flow for make-up, and a controllable valve to prevent contents of the Borated Water Storage Tank (BWST) from draining to the reactor building sump during hot shutdown. Cables for the 1 above functions are protected in a fire barrier envelope which contains 2.5-inch conduit l protected by Thermo Lag. The envelope has an actual fire endurance rating of 39 minutes as determined in a fire endurance test conducted in accordance with ASTM E-119.
2.8 Fire Zone FH-FZ-6 This zone is located on elevation 281 of the fuel handling building and measures approximately 45 feet x 20 feet x 20 feet high. The principal combustibles in the area are approximately 20 gallons of lube oil. The Thermo-Lag present in this area contributes 70% of the fire loading. The fire loading for this area is considered low. l l
Fire protection features for this zone include a zone-wide ionization smoke detection system which actuates an alarm in the control room as well as a 2-inch drain connection for attaching a hose in addition, a portable dry chemical extinguisher is available in an adjacent stairwell. ;
in a letter dated December 23,1998, the licensee committed to install an area wide automatic wet pipe sprinkler system in this zone, it is estimated by the licensee that the full fire brigade complement could bring manual suppression to bear on a fire in this fire area in 15 minutes.
The specific safe shutdown circuits and equipment protected by the existing Thermo-Lag fire barriers in this fire area are associated with the following functions: !
e Make-up and Supporting Functions e RCS Pressure e Reactor Coolant Pump Thermal Barrier Cooling e Steam Generator Pressure and Level e Source Range Monitoring e Electrical Power System .
These functions require fire barrier protection in order to insure a safe shutdown path is available if a fire eliminates all other unprotected circuits and equipment in this fire zone.
Cables for the above functions are protected in five different fire barrier envelopes which all contain 4-inch conduit protected by Thermo-Lag. The envelopes have an actual fire endurance rating of 50 minutes as determined in a fire endurance test conducted in accordance with ASTM E-119.
2.9 Fire Zone ISPH-FZ-1
= This fire zone is located in the intake screen and pumphouse, elevation 308, with dimensions 48 feet x 42 feet x 21 feet high. The principal combustibles in the area are exposed cable insulation, electncal switchgear, approximately 2 gallons of lube oil, plastics, and transients.
Most of the cable insulation in the area meets the IEEE 383 standard for flammability. The fire loading in the area is low.
Fire protection features in this zons include a zone-wide automatic wet pipe sprinkler system and portable extinguishers (dry chemical and CO2 ). Hose protection is available from a yard hydrant located outside the building. A zone-wide ionization smoke detection system will actuate alarms in the main control room. it is estimated by the licensee that the full fire brigade complement could bring manual suppression to bear on a fire in this fire area in 25 minutes.
The specific safe shutdown circuits and equipment protected by the existing Thermo-Lag fire barriers in this fire area are associated with the following functions:
e Nuclear Services River Water e Electrical Power System These circuits require fire barrier protection in order to insure a safe shutdown path is available if a fire damages the other unprotected circuits and equipment in this fire area. Cables for the above functions are protected in 2 fire barrier envelopes which contain 4-inch conduit and 3-inch armor cable protected by Thermo-Lag. The actual fire endurance rating of the 4-inch conduit is 50 minutes, while the 3-inch armored cable was given a rating of 39 minutes, based on the performance of a 2-inch diameter aluminum conduit in a fire endurance test conducted in accordance with ASTM E-119. One envelope passes 2 feet over a loaded cable tray in one location.
2.10 Fire Zone ISPH-FZ-2 This fire zone is located in the intake screen and pumphouse, elevation 308, with dimensions 48 feet x 42 feet x 21 feet high. The principal combustibles in the area are exposed cable insulation, minor amounts of lube oil, plastics, and transients. Most of the cable insulation in the area meets the IEEE 383 standard for flammability. The fire loading in the area is low.
Fire protection features in this zone include a 7one-wide automatic wet pipe sprinkler system and a portable CO2 extinguisher. Additional portable extinguishers are located in adjacent fire zones. Hose protection is available from a yard hydrant located outside the building. A zone-wide ionization smoke detection system will actuate alarms in the main control room, it is estimated by the licensee that the full fire brigade complement could bring manual suppression to bear on a fire in this fire area in 25 minutes.
The specific safe shutdown circuits and equipment protected by the existing Thermo-Lag fire barriers in this fire area are associated with the following functions:
e Nuclear Services River Water o Electrical Power System
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l These circuits require fire barrier protection in order to insure a safe shutdown path is available l
- if a fire damages the other unprotected circuits and equipment in this fire area. Cables for the above functions are protected in 2 fire barrier envelopes which contain 4-inch conduit and 3-inen armor cable protected by Thermo-Lag. The actual fire endurance rating of the 4-inch l
conduit is 50 minutes, while the 3-inch armored cable was given a rating of 39 minutes, based !
on the performance of a 2-inch diameter aluminum conduit in a fire endurance test conducted l
in accordance with ASTM E-119. These envelopes pass 2 feet over a loaded cable tray in two places, but are not directly over any electrical switchgear.
3.0 EVALUATION '
These fire areas / zones do not currently meet the technical requirements of Section Ill.G.2.c of Appendix R because the Thermo-Lag electrical raceway fire barrier envelopes for the fire areas / zones discussed above are not rated at 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> as per the requirements of NRC Generic Letter 86-10 Supplement 1. Section Ill.G.2.c of Appendix R could only be satisfied by protecting each envelope with a 1-hour fire rated barrier.
In its submittal, the licensee states that modification of the identified fire barriers to achieve a 1-hour fire rating per ASTM E-119 would cost approximately $1.0 million which represents a substantial cost hardship with minimal safety enhancement.
The staff holds to a defense-in-depth philosophy when determining adequate fire protection.
In areas where fire barriers are required to be rated at 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, barriers that have actual fire endurance ratings of less than 1-hour are acceptable only if the fire area / zone also has automatic detection and fire suppression systems provided in accordance with applicable NFPA standards and if the fire hazard to the Thermo-Lag protected envelope is minimal. The fire zones / areas reviewed above do not have any Therme Lag envelopes rated at 1-hour or greater, and therefore, the criteria for granting an exemption, for the most part, will be based on the availability of automatic detection and suppression systems and the fire hazards present in each fire area / zone. These systems and minimizing fire hazards provide systems defense in depth.
Due to the variations between the different fire zones and areas, an individual evaluation of postulated fires and fire protection features is presented for each of the 10 fire zones / areas below:
3.1 Fire Zone AB-FZ-3 For a postulated fire in fire zone AB-FZ-3, redundant trains of safe shutdown circuits for make-up and supporting fcnctions could be lost. These circuits must be mainained functional and free from fire damage to assure safe shutdown of the plant.
If a fire were to .accur in this fire zone, indication of the fire would be received in the control room, through the ionization smoke detection system, and if necessary, the fire brigade would be dispatched soon thereafter. Fire brigade response to this fire zone upon receipt of an ,
alarm has been estimated by the licensee at 15 minutes. Manual fire fighting equipment (hand !
held fire extinguishers and hose stations) is available in or adjacent to this fire zone.
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This zone is provided with automatic detection but is not provided with automatic suppression, and therefore reasonable assurance has not been provided by the licensee that the Thermo-Lag protected cables will remain free from fire damage following a fire in this zone.
3.2 Fire Zone AB-FZ-4 For a postulated fire in fire zone AB-FZ-4, redundant trains of safe shutdown circuits for reactor coolant pump seal injection and reactor coolant pump thermal barrier cooling could be lost. These circuits must be mair'tained functional and free from fire damage to assure safe shutdown of the plant.
A fire in this fire zone is postulated to be a slowly developing cable fire, with possible ignition sources including cable overioad or transient combustibles. Exposure of the protected envelope to fire is possible through the ignition of cable insulation.
If a fire were to occur in this fire zone, indication of the fire would be received in the control room, through the ionization smoke detection system, and the automatic pre-action system
..ould initiate suppression if the fire continued to grow. If necessary, the fire brigsde would be dispatched soon thereafter. Fire brigade response to this fire zone upon receipt of an alarm has been estimated by the licensee at 15 minutes. Manual fire fighting equipment (hand held fire extinguishers and hose stations) is available in or adjacent to this fire zone.
This zone is provided with both automatic detection and suppression, and therefore ;
reasonable assurance is provided that the Thermo-Lag protected cables will remain free from l fire damage. l 3.3 Fire Zone AB-FZ-5 For a postulated fire in fire zone AB-FZ-5, redundant trains of safe shutdown circuits for make-up supporting function and make-up could be lost. These circuits must be maintained functional and free from fire damage to assure safe shutdown of the plant.
A fire in this fire zone is postulated to be a slowly developing cable fire, with possible ignition sources being transient combustibles. Exposure of the protected envelope to fire is possible through the ignition of cable insulation.
If a fire were to occur in the vicinity of the Thermo-Lag envelope in this fire zone, indication of the fire would be received in the control room, tnrough the localized ionization smoke detection system. If necessary, the fire brigade would be dispatched soon thereafter. Fire brigade response to this fire zone upon receipt of an alarm has been estimated by the licensee at 15 minutes. Manual fire fighting equipment (hand held fire extinguisher and a hose station) is available in this fire zone.
This zone offers automatic detection in the area of the Thermo-Lag envelope but is not provided with automatic suppression, and therefore reasonable assurance has not been provided by the licensee that the Thermo-Lag protected cables will remain free from fire damage following a fire in this zone.
3.4 Fire Zone AB-FZ-7 For a postulated fire in fire zone AB-FZ-7, redundant trains of safe shutdown circuits for make-up supporting function (nuclear services closed cooling water) could be lost. These circuits must be maintained functional and free from fire damage to assure safe shutdown of the plant.
A fire in this fire zone is postulated to be a slowly developing cable fire, with possible ignition sources being an overload or a pump lube oil fire. Exposure of the protected envelope to fire is possible through the ignition of cable insulation.
If a fire were to occur in this fire zone, indication of the fire would be received in the control room, through the ionization smoke detection system. This would actuate an automatic pre-action sprinkler system to provide a water curtain for the open passageway to an adjacent fire zone. The fire zone in question does not have automatic suppression installed. If necessary, the fire brigade would be dispatched soon thereafter. Fire brigade response to this fire zone upon receipt of an alarm has been estimated by the licensee at 15 minutes. Manual fire fighting equipment (hand held fire extiriguishers and a hose station) is available adjacent to this fire zone.
This zone offers automatic detection but is not provided with automatic suppression, and therefore adequate assurance has not been provided by the licensee that the Thermo-Lag protected cables will remain free from fire damage following a fire in this zone.
3.5 Fire Zone CB-FA-1 For a postulated fire in fire area CB-FA-1, redundant trains of safe shutdown circuits for make-up and supporting fundions, RCS pressure control, RCP thermal barrier cooling functions, nuclear services closed cycle cooling, decay heat closed cycle cooling, and electrical power system function could be lost. These circuits must be maintained functional and free from fire de nage to assure safe shutdown of the plant.
A fire in this fire zone is postulated to be a slowly developing cable fire, with possible ignition sources being overload or transient combustibles. Exposure of the protected envelope to fire is possible through the ignition of cable insulation.
If a fire were to occur in this fire zone, indication of the fire would be received in the control room, through the ionization smoke detection system which is present above the suspended ceiling. An automatic wet pipe sprinkler system which is below the suspended ceiling, would actuate to suppress a fire should it continue to form. If necessary, the fire brigade would be dispatched soon thereafter. Fire brigade response to this fire zone upon receipt of an alarm has been estimated by the licensee at 15 minutes. A hand held dry chemical fire extinguisher is available adjacent to this fire zone.
The gas detection to be provided in the radiochemistry lab and the concealed spaces above the suspended ceiling where the acetylene gas line is routed provides reasonable assurance that a gas leak will be detected promptly by licensee personnel and the acetylene can be isolated at the source prior to reaching the lower explosive limit. This area is also provided with automatic detectior, eove the suspended ceiling and automatic suppression below the
suspended ceiling and therefore there is reasonable assurance that the safe shutdown circuits in this fire zone will remain free of fire damage.
3.6 Fire Zone FH-FZ-1 m 's postulated fire in fire zone FH-FZ-1, redundant trains of safe shutdown circuits for ir.ske-up and supporting funcbons, RCS pressure control, RCP thermal barrier cooling functions, nuclear services river water, decay heat river water, and electrical power system funcbon could be lost. These circuits must be maintained functional and free from fire damage to assure safe shutdown of the plant.
A fke in this fire zone is postulated to be a slowly developing cable fire, with possible ignition sources being transient combustibles. Exposure of the protected envelope to fire is possible through the ignition of cable insulation.
If a fire were to occur in this fire zone, indication of the fire would be received in the control room, through the ionization smoke detection system. An automatic wet pipe sprinkler system would actuate to suppress a fire should it continue to form. If necessary, the fire brigade would be dispatched soon thereafter. Fire brigade response to this fire zone upon receipt of an alarm has been estimated by the licensee at 15 minutes. A fire hose station is available in this fire zone and hand-held dry chemical fire extinguishers and an additional hose station are available adjacent to this fire zone.
This zone is provided with both automatic detochon and suppression, and therefore reasonable assurance is provided that the Thermo-Lag protected cables will remain free from fire damage.
3.7 Fire Zone FH-FZ-2 For a postulated fire in fire zone FH-FZ-2, redundant trains of safe shutdown circuits for make-up and supporting functions, decay heat, and RCP thermal barrier cooling could be lost.
These circuits must be maintained functional and free from fire damage to assure safe shutdown of the plant.
A fire in this fire zone is postulated to be a slowly developing cable fire, with possible !gnition sources beir.g transient combustibles. Exposure of the protected envelope to fire is possible through the ignition of cable insulation.
If a fire of significant magnitude were to occur in this fire zone, indication of the fire would be received in the control room, through the automatic wet pipe sprinkler system actuation. If necessary, the fire brigade would be dispatched soon thereafter. Fire brigade response to this fire zone upon receipt of an alami has been estimated by the licensee at 15 minutes. A fire hose stabon and hand-held dry chemical and CO, fire extinguishers are available adjacent to this fire zone as well as an additional hose station in the vicinity of the fire zone. Manual suppression could be brought to bear on a fire within this zone in 15 minutes or less.
This zone offers automatic suppression but is not provided with automatic detection, and therefore adequats assurance has not been provided by the licensee that the Thermo-Lag protected cables will remain free from fire damage following a fire in this zone.
3.8 Fire Zone FH-FZ-6 For a postulated fire in fire zone FH-FZ 6, redundant trains of safe shutdown circuits for make-up and supporting functions, RCS pressure control, steam generator pressure and level functions, source range monitoring, electrical power system function, and RCP thermal barrier cooling functions could be lost. These circuits must be maintained functional and free from fire damage to assure safe shutdown of the plant. A firs in this fire zone is postulated to be a slowly developing cable fire, with possible ignition sources being transient combustibles.
Exposure of the protected envelope to fire is possible through the ignition of cable insulation.
If a fire were to occur in this fire zone, indication of the fire would be received in the control room by the ionization smoke detection system or through the actuation of the wet pipe sprinkler system to be installed. If necessary, the fire brigade would be dispatched soon thereafter. Fire brigade response to this fire zone upon receipt of an alarm has been estimated by the licensee at 15 minutes. A 2-inch drain connection is provided to attach a fire hose to, and a hand-held dry-chemical fire extinguisher is available adjacent to this fire zone.
Manual suppression could be brought to bear on a fire within this zone in 15 minutes or less.
This zone is provided with automatic detection and will be provided with automatic suppression. Therefore, subject to the installation of an automatic suppression system discussed above, there is reasonable assurance that the Thermo-Lag protected cables will remain free from fire damage following a fire in this zone.
3.9 Fire Zone ISPH-FZ-1 For a postulated fire in fire zone ISPH-FZ-1, redundant trains of safe shutdown circuits for nuclear services river water and electrical power system function could be lost. These circuits must be maintained functional and free from fire damage to assure safe shutdown of the plant.
A fire in this fire zone is postulated to be a slowly developing cable fire, with possible ignition l source being the electrical switchgear. Exposure of the protected envelope to fire is possible l through the ignition of cable insulation.
If a fire were to occur in this fire zone, indication of the fire would be received in the control room by the ionization smoke detection system. A zone-wide automatic wet pipe sprinkler system is available to suppress a fire should it develop, and portable extinguishers (dry chemical and CO2 ) are available in the fire zone if necessary, the fire brigade would be dispatched soon thereafter. Fire brigade response to this fire zone upon receipt of an alarm has been estimated by the licensee at 25 minutes. A portable extinguisher and yard hydrant are located outside the area and are available for fire fighting in this zone.
Envelope 1SHD-FB01 is a 4-inch diameter conduit that passes through the area, has an actual fire rating of 50 minutes, and does not pass in the vicinity of any in-situ combustibles.
Envelope 1SHD-FB05, containing the 3-inch diameter armor cable, passes directly over a j
loaded cable tray in one location. The licensee has rated this envelope at 39 minutes, based on fire tests of Thermo-lag protected 2 inch aluminum conduit.
Based on the above, reasonable assurance has been provided that the Thermo-Lag protected cables in this zone will remain free from fire damage.
3.10 Fire Zone ISPH-FZ-2 For a postulated fire in fire zone ISPH-FZ-2, redundant trains of safe shutdown circuits for nuclear services river water and electrical power system function could be lost. These circuits must be maintained functional and free from fire damage to assure safe shutdown of the plant.
A fire in this fire zone is postulated to be a slowly developing cable fire, with a possible ignition source being the electrical switchgear. Exposure of the protected envelope to fire is possible through the ignition of cable insulation.
If a fire were to occur in this fire zone, indication of the fire would be received in the control room by the ionization smoke detection system. An area-wide automatic wet pipe sprinkler system is available to suppress a fire should it develop, and a portable CO2 extinguisher is available in the fire zone if necessary, the fire brigade would be dispatched soon thereafter.
, Fire brigade response to this fire zone upon receipt of an alarm has been estimated by the licensee at 25 minutes. A portable extinguisher und yard hydrant are located outside the area and ere available for fire fighting in this zone.
Envelope 1SHD FB03 is a 4-inch diameter conduit that passes through the area, has an actual fire rating of 50 minutes, and does pass over a loaded cable tray in two places. Envelope i 1SHD-FB06, containing the 3-inch diameter armor cable, also passes directly over a loaded l
cable tray in two places. The licensee has rated this envelope at 39 minutes, based on fire tests of Thermo Lag protected 2-inch aluminum conduit.
l Based on the above, reasonable assurance has been provided that the Thermo-Lag protected l cables in this zone will remain free from fire damage.
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4.0 CONCLUSION
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4.1 Fire Zones AB-FZ-4, CB-FA-1, FH-FZ-1, FH FZ 6, IPSH-FZ-1 and IPSH-FZ-2 The staff believes that reasonable assurance has been provided through the availability of automatic suppression and detection in these fire areas / zones to ensure that one division of safe shutdown components necessary to achieve safe shutdown will remain free of fire damage in the event of a fire. Therefore, the underlying purpose of the rule is satisfied.
Accordingly, the request for an exemption from the requirements of 10 CFR 50 Appendix R, Section Ill.G.2.c with respect to these fire zones meets the special circumstances delineated in 10 CFR 50.12(a)(2)(ii), i.e., the application of the regulation in these particular circumstances is not necessary to achieve the underlying purpose of the rule. While the installed Thermo-Lag barriers in the fire zones listed above have less than a 1-hour fire endurance rating, they provide some resistance to fire. The areas where the Thermo-Lag envelopes are located have
, a low combustible loading in the area of the envelopes, have available manual suppression l
i capability, and are equipped with automatic suppression and detection. Under these circumstances, there is an adequate level of fire safety such that one safe shutdown train will be free of fire damage, and therefore, the underiying purpose of the rule is met.
On the basis of the NRC staff evaluation, and circumstances described above, the staff has concluded that an exemption from the technical requirements of Section Ill.G.2.c of Appendix R to the extent that it requires the enclosure of cables of one redundant train of safe shutdown equipment in a 1-hour fire rated barrier, should be granted for fire areas / zones AB-FZ 4, CB-FA-1, FH-FZ-1, FH FZ-6, IPSH-FZ-1 and IPSH-FZ-2.
4.2 Fire Areas / Zones AB-FZ-3, AB FZ-5, AB-FZ-7, and FH-FZ-2 Fire zones AB-FZ-3, AB FZ-5, and AB-FZ-7, are not provided with automatic suppression and automatic detection. FH FZ-2 has automatic suppression, but not detection.
The licensee has failed to provide reasonable assurance that one division of safe shutdown components necessary to achieve safe shutdown will remain free of fire damage in the above zones. On the basis of this evaluation, the staff has concluded that the licensee's request for an exemption from the technical requirements of Section Ill.G.2.c of Appendix R should be denied for fire zones AB-FZ-3, AB-FZ-5, AB-FZ-7, and FH-FZ-2.
Principal Contributors: C. S. Bajwa E. Connell R. Jenkins T. Colbum Date: April 20,1999
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