ML20117M550
| ML20117M550 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 09/09/1996 |
| From: | Adney R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-86-10, GL-92-08, GL-92-8, TAC-M85604, TAC-M85605, NUDOCS 9609170509 | |
| Download: ML20117M550 (30) | |
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Tennessee Valley Authority, Post Offee Box 2000, Soddy Daisy, Tennessee 37379-2000 R.J. Adney Site Vce President Sequoyah Nuclear Plant September 9,'1996 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555 Gentlemen:
In the Matter of ) Docket Nos. 50-327 Tennessee Valley Authority ) 50-328 SEQUOYAH NUCLEAR PLANT (SON) - UPDATE OF TVA'S JUNE 15,1995, '
RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION REGARDING GENERIC LETTER (GL) 92-08, "THERMO-LAG 330-1 FIRE BARRIERS"
References:
- 1. TVA letter to NRC dated February 10,1994, "Sequoyah Nuclear Plant (SON)- Request for AdditionalInformation Regarding Generic Letter 92-08, 'Thermo-Lag 330-1 Fire Barriers,' Pursuant to 10 CFR 50.54(f) - Sequoyah Nuclear Plant, Units 1 and 2 (TAC Nos. M85604 and M85605)"
- 2. TVA letter to NRC dated March 22,1995, "Sequoyah Nuclear Plant (SON) - Response to the Follow-Up Request for Additional Information (RAI) Regarding Generic Letter (GL) 92-08, Thermo-Lag 330-1 Fire t Barriers"
- 3. TVA letter to NRC dated June 15,1995, "Sequoyah (SON) and Watts { i Bar (WBN) Nuclear Plants - Update of TVA's March 22,1995, Resp 3:,o *v NdC Request for Additionalinformation Regarding {
Generic Letter (GL) 92-08, Thermo-Lag 330-1 Fire Barriers" The purpose of this letter is to provide additionalinformation and an update to the NRC 0l concerning the ongoing activities pursuant to GL 92-08 related to Thermo-Lag 330-1 Electrical Raceway Fire Barrier Systems (ERFBS) installed at SON. Reference 1 described the plan for addressing the Thermo-Lag 330-1 ERFBS installed at SON. This plan was updated by Reference 2.
9609170509 960909 POR. ADOCK 05000327 P PDR
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. U.S. Nuclear Regulatory Commission Page 2 - .
September 9,1996' l
TVA has performed Thermogravimetric Analysis (TGA) chemical testing on the Thermo-Lag 330-1 material. Based on this testing, TVA determined there was a difference between the TGA curves obtained from some of the older materialinstalled at SON and the more recent material used in qualification testing and installed at WBN.
This difference was described in Reference 3, which reported that additional I
evaluations would be performed on this material to determine its acceptability.
Reference 3 also indicated that the results of +his evaluation would be contained in a future submittal, j TVA's further evaluation of the older material with differing TGA curves included the ]
. performance of a full scale fire test on January 17,1996, at Omega Point >
Laboratories, San' Antonio, Texas. The purpose of this test was to determine whether the older material would perform in a manner similar to the material which was used in TVA's other fire endurance testing. The test demonstrated that there is no difference ,
l in' material performance and that the older material can be considered qualified by the )
TVA test program. Enclosure 1 provides a more detailed summary of the test results.
Enclosure 2 provides TVA's disposition of issues to resolve Thermo-Lag 330-1 ERFBS j applications at SON.
The question regarding acceptability of the installed materialintroduced an uncertainty into TVA's program for addressing Thermo-Lag 330-1 ERFBS at SON which was not ,
foreseen in Reference 1. Walkdowns, evaluations, and modifications now necessary ;
3 to resolve the Thermo-Lag 330-1 issues are scheduled for completion by October 1, ;
1999. . This schedule is based upon competing resources from the overall site budget for other regulatory and reliability issues. Compensatory measures will remain in place pending final TVA resolution.
Enclosure 3 contains the commitments discussed in Enclosure 2. These commitments ,
replace the commitments previously contained in Reference 1 (and supplemented by ;
Reference 2). I l
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or U.S. Nuclear _ Regulatory Commission Page 3' September 9, 1996 Please direct questions concerning this issue to W. C. Ludwig at (423) 843-7460.
. Sincerely, R.J.Adney d b for me A w 1M 2' [-..
thi ' *.
orday of subscri tp and 1996
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T40tayPLblic My Commission Expires 8 O/- [
Enclosures cc (Enclosures):
Mr. R. W. Hernan, Project Manager Nuclear Regulatory Commission
' One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852-2739
- NRC Resident inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy-Daisy, Tennessee 37379-3624 Regional Administrator U.S. Nuclear Regulatory Commission Region 11 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323-2711
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ENCLOSURE 1 I
SUMMARY
RESULTS OF THE TENNESSEE VALLEY AUTHORITY .
I SEQUOYAH NUCLEAR PLANT (SON) JANUARY 17,1996, j FULL SCALE, ONE-HOUR FIRE ENDURANCE TEST OF THERMO-LAG 330-1 ELECTRICAL RACEWAY FIRE BARRIER SYSTEM i
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BACKGROUND i
During the installation of the Thermo-Lag 330-1 Electrical Raceway Fire Barrier ;
Systems (ERFBS) at Watts Bar (WBN) in the summer of 1995, TVA located a large stock of previously procured Thermo-Lag materials in storage at the TVA Hartsville Distribution Center. This material was procured over approximately a 10-year period and used in numerous Appendix R projects at Browns Ferry (BFN), Sequoyah (SON), {
and WBN. Prior to using this New Old Stock (NOS) material at WBN, each piece was - 1 subjected to the Quality Assurance (QA) acceptance testing requirements of TVA 'j General Engineering Specification (G-Spec) G-98, " Installation, Modification, and .
Maintenance of Electrical Raceway Fire Barrier Systems." As a part of the QA :
requirements, a sample from each lot of material was also subjected to l Thermogravimetric Analysis (TGA) and Infrared (IR) Spectroscopy to verify chemical composition. The majority of this material was found to be similar to materials used in !
the TVA Thermo-Lag qualification testing. However, in the process of performing the TGA, TVA determined there was a potential difference between the circa 1985 vintage y materials and those used in the TVA Thermo-Lag 330-1 ERFBS qualification and rating j fire tests. This material was not used for new installations at any TVA facility pending ,
additional evaluation. Further review of these lot numbers indicated that some of these same lot numbers had been previously installed at SON. .
RESOLUrlON The original TGA acceptance profile for Thermo-Lag 330-1 was developed by collecting i and analyzing TGA profiles from over thirty lots of material used in the TVA l qualification fire endurance testing program. This methodology provided a direct - ;
correlation between the TGA profile and Thermo-Lag 330-1 lots that had demonstrated i acceptable performance in the TVA qualification testing (fire, ampacity, seismic). This ,
profile demonstrated a consistent bandwidth which was translated into the material !
acceptance profile. In order to determine if the Thermo-Lag 330-1 materials that produced a TGA profile outside this acceptance profile were acceptable for installation, !
TVA determined that an additional full scale one-hour fire endurance test using the material with the differing TGA profile was necessary. This additional fire test was also designed to focus on two additional factors. They were: !
- 1. Determine the effects of cable mass in conduits protected w!th Thermo-Lag 330-1 i
. ERFBS, t
- 2. Determine the effects of minor variations in installation techniques on the i Thermo-Lag 330-1 ERFBS performance (e.g., stainless steel banding, no external !
stress skin reinforcement on mitered radius). [
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TEST CONFIGURATIONS The test consisted of six comparable conduit configurations. Each of the six conduit !
configurations was assembled into an "L-shaped" configuration having a horizontal ;
dimension of approximately 70 inches and an approximate vertical dimension of ;
36 inches inside the furnace (see Figures 1 and 2). Each vertical section transitioned !
l through the top of the test deck into a standard radius 90-degree elbow and continued ;
horizontally out through the front of the test deck. Testing of multiple configurations l
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was not needed to demonstrate acceptable performance of the material. Tests qualifying acceptable material for many configurations have been performed. These tests have been well documented as a part of the WBN licensing process and their .i results are reflectea in TVA Mechanical Design Standard DS-M17.2.2 " Electrical ;
Raceway Fire Barrier Systems," and NRC NUREG-0847, Supplement 18. Listed below ;
is a summary description of each ERFBS configuration tested and the variables j included.' All the conduits used in this test were aluminum since previous tests identified that aluminum conduits were worst case (i.e., experienced the highest internal temperature for a single-layer Thermo-Lag 330-1 design) and would bound -
similar ERFBS installed on steel conduits.
~ Con' duit A Size = 1 inch, cable fill = none o
This conduit configuration determined the acceptability of installing an upgrade M consisting of new nominal 3/8-inch Thermo-Lag 330-1 (that has demonstrated [
acceptable TGA results) over an older installation of minimum 1/2-inch ,
Thermo-Lag 330-1 (that has demonstrated a variance in TGA results). Material from +
lot numbers that produced the greatest TGA variation from the requirements of G Spec G-98 were used wherever practical. TVA had previously tested this two-layer design t (nominal 5/8 inch + 3/8 inch on a 1-inch steel conduit) using materials meeting TGA !
QA requirements and determined the ERFBS will maintain acceptable temperatures (Reference TVA Design Standard DS-M17.2.2 Test 6.1.3 / Omega Point Laboratories j Project No. 11210-94943a).
i Conduit B i
Size = 3 inches, cable fill = none i This conduit configuration determined the acceptability of Thermo-Lag 330-1 materials
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that have demonstrated a minor variance in TGA profiles. The lots of i Thermo-Lag 330-1 material used for this conduit ERFBS are new nominal 5/8-inch i material that was restricted from installation at WBN due to a minor variation in the j TGA profile. The ERFBS was a single-layer design. TVA had previously tested this i arrangement using materials meeting TGA QA requirements and determined the ERFBS l should maintain acceptable temperatures for approximately 54 minutes (Reference ,
TVA Design Standard DS-M17.2.2, Test 6.1.4 / Omega Point Laboratories Project No.11210-94943b).The results of this ERFBS performance were also evaluated against Conduits C and D. ,
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' Conduit C - l l
Size = 3 inches, cable fill = five cables, each 7/C #16 AWG,12.33% fill,0.85 lb./ft. .;
i This conduit configuration determined the acceptability of Thermo-Lag 330-1 materials that have demonstrated a variance in TGA profiles when tested in accordance with
' .G Spec G-98. '.The lots of Thermo-Lag 330-1 used for this conduit ERFBS were
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3-minimum 1/2-inch material available in TVA stock (referred to as "New Old Stock" or NOS). Material from lot numbers that produced the greatest TGA variation from the requirements of G-Spec G-98 were used wherever practical. This conduit also incorporated an offset to test installation techniques involving soaking the
.Thermo-Lag 330-1 materiaiin water to soften prior to installation. The ERFBS was a single-layer design. The results of this ERFBS performance were evaluated against Conduit Configurations B and D.
Conduit D Size = 3 inches, cable fill = sixteen cables, each 7/C #16 AWG,39.45% fill, _
2.70 lb./ft.
This conduit configuration determined the acceptability of Thermo-Lag 330-1 materials
' that have demonstrated a variance in TGA profiles when tested in accordance with
- G Spec G-98. The lots of Thermo-Lag 330-1 materia! used for this conduit ERFBS are NOS minimum 1/2 inch available in TVA stock. Material from lot numbers that produced the greatest TGA variation from the requirements of G-Spec G-98 were used wherever practical. The ERFBS was a single-layer design. The results of this ERFBS performance were evaluated against Conduit Configurations B and C.
' Conduit E Size = 4 inches, cable fill = none
- This conduit configuration determined the acceptability of Thermo-Lag 330-1 materials
.that have demonstrated a variance in TGA profiles when tested in accordance with G-Spec G-98. The lots of Thermo-Lag 330-1 materials used for this conduit ERFBS were NOS minimum 1/2 inch available in TVA stock. The ERFBS was a single-layer design'. Material from lot numbers that produced the greatest TGA variation from the requirements of G Spec G-98 were used wherever practical. The results of this ERFBS
. performance were evaluated against Conduit Configuration F.
Conduit F Size = 4 inches, cable fill = none This conduit configuration served as the control sample for Conduit E. Materials that have demonstrated an acceptable TGA profile when tested in accordance with G-Spec G 98 were used. The lots of Thermo-Lag 330-1 materials used for this conduit ERFBS are NOS minimum 1/2 inch available in TVA stock. The ERFBS was a single-layer design. The results of this ERFBS performance were evaluated against Conduit
. Configuration E.
Each conduit contained an instrumented bare copper #8 AWG to record the internal
. temperatures inside the conduit during the test. The test assemblies wero-instrumented, and the test was performed in accordance with the guidance provided by Supplement 1 to Generic Letter (GL) 86-10' A senior fire protection engineer from the
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NRC/NRR was present to witness the test.
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RESULTS.
. All six Thermo-Lag 330-1 ERFBS described above met the thermal acceptance criteria and passed the hose stream test as defined in Supplement 1 to GL 86-10. Listed below is a summary table of the thermal performance.
THERMAL PERFORMANCE OF THERMO-LAG 330-1 ERFBS 1
, Conduit Conduit Conduit Bare #8 Bare #8 c onfiguration AT ave.( F) AT max.(0F) AT ave.( F) AT max.( F) d' A- 157 161 151 159 B 248 300 215 258 :
C 221' 275 156 239 Y
! D. 199 238 112 166 E 178 210 151 173 F 189 230 164 192 1
Conduits E and F were both constructed of NOS materials of similar thickness and texture. The TGA of material used on Conduit F produced an acceptable profile i equivalent to all previous Thermo-Lag 330-1 used throughout the TVA testing program.
The TGA of Conduit E was outside the profile, and prior to this test, would not be installed in a new TVA installation. Evaluating the thermal results of Conduit j Configurations E and F shows that the older vintage SON Thermo-Lag 330-1 materials
- with the variance in TGA performed slightly better than the material bounded by previous TGA testing. The temperature profiles were uniform and consistent across I the conduit and bare No. 8. Conduits B, C, and D also demonstrated acceptable results. Disassembly of Conduit E and F, after the completion of the fire endurance and hose stream test, documents their similar physical performance. On both ERFBS, there was between 1/2 to 1 inch of char on the outside surface with approximately
- 1/4 inch of uncharred material remaining on the conduit. !t should also be noted that
- Conduit Configuration B (i.e., no cable filt) maintained acceptable temperatures for the
, one-hour rating period. This performance exceeds that of earlier TVA tests (Omega Point Laboratories Project No. .11210-94943b)and further supports the results .
. obtained in the comparison between Conduits Configurations E and F. Conduit ,
Configuration A demonstrated the acceptability of installing new Thermo-Lag 330-1 over SON vintage NOS materials with no compromise in overall ERFBS performance.
Based upon these test results, TVA has redefined and expanded the acceptable TGA profile for Thermo-Lag 330-1 QA requirements.
, . Evaluating the results of Conduit Configurations B, C, and D show that cable mass
. inside the ERFBS does provide a significant heat sink that enhances the system's thermal performance. Listed be!ow is a summary table describing the effects of cable fill on the thermal performance of the ERFBS.
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5-EFFECTS OF CABLE ON ERFBS PERFORMANCE Conduit ~ Conduit Conduit Bare #8 Bare #8 Confiauration AT ave.(*F) AT max.(0F) - AT ave.( F) AT max.( F) l B - (0 % fill) 248 300 215 258 D - (40% fill)- 199 238 112 166 l AT attributed 49 62 103 92 ;
to cable fill ( F)
Evaluating the results of the 1/2 inch stainless steel banding (both exposed and.
protected with approximately 3/8-inch skim coat of Thermo-Lag 330-1 trowel grade material) show that such installations experience slightly higher internal temperatures,
'but are acceptable for continued use on existing conduits 3 inches and larger. The highest temperature rise recorded on the back side of the Thermo-Lag 330-1 preformed sections directly under the band was (365 degrees Fehrenheit [F] - 65 degrees F _ l ambient) = 300 degrees F. This worst-case, maximum single-point temperature rise .
was 25 degrees F below the maximum allowable. The best performance for a ;
protected band was (247 degrees F - 65 degrees F) = 182 degrees F. The best j performance for an unprotected band was (254 degrees F - 65 degrees F) j
- = 189 degrees F.
The 90-degree radius conduit bends were constructed using the mitered piece technique. This technique involves cutting the preformed Thermo-Lag 330-1 conduit .
sections into small pie shaped pieces (approximately 1 to 3 laches) to conform to the conduit radius. In the majority of the previous TVA tests, a layer of reinforcing
- external stress skin was added to these sections. In an effort to replicate a typical SON configuration, this additional reinforcement upgrade was not used in this test.
, This test demonstrated that there were no thermal or mechanical structural failures even without this additional reinforcement.
I All six conduit ERFBS were constructed using Thermo-Lag 330-1 trowel grade material
.that had exceeded the vendors recommended six-month shelf life and has been !
- recertified using the TVA developed methods and procedures as required by G-Spec
- G 98. There was no ' noticeable difference in performance of the new versus recertified .
- trowel grade .naterial when compared to other TVA fire tests. ;
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- Thickness measurements were performed and documented for all Thermo-Lag 330-1 ;
'- materials used in the test. The NOS material thickness consistently ranged between a
- minimum 1/2 inch to a maximum 3/4 inch with the average being nominal 5/8 inch. l
- This is based on samples taken from 15 different NOS lots. ;
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6-CONCLUSIONS:
Based upon the results of this fire test, TVA has concluded the following:
- 1. The chemical' composition of the Thermo-Lag 3301 materialinstalled at SON is acceptable and bounded by the TVA Thermo-Lag testing program.
2.' The nominal thickness of the Thermo-Lag 330-1 materials installed at SON can be approximated as nominal 5/8 inch with a tolerance of +/- 1/8 inch.
- 3. Nominal 5/8-inch Thermo-Lag 330-1 properly installed on a 3-inch conduit will provide a rated one-hour ERFBS regardless of cable fill.
- 4. The use of 1/2-inch stainless steel banding installed on 3 inch and larger conduits with nominal 5/8-inch Thermo-Lag 330-1 ERFBS is acceptable.
- 5. The TVA developed methods and procedures for. extending the shelf life of properly controlled Thermo-Lag 330-1 trowel grade material is acceptable and has been verified by full scale fire testing.
- 6. New Thermo-Lag 330-1 materialis compatible with older Thermo-Lag 330-1 material in performing upgrades.
- 7. External stress skin reinforcement is not required on properly installed mitered radius sections for 3 inch and larger conduits.
These test results are to be included in Mechanical Design Standard DS-M17.2.2,
" Electrical Raceway Fire Barrier Systems." A copy of the Omega Point Laboratories test report, " Fire Endurance Test of Thermo-Lag 3301 Fire Protective Envelopes (1-inch,3-inch, and 4-inch diameter aluminum conduit) Project No. 11210-98892"is available at SON for review.
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FIGURE 1 PLAN VIEW - (BELOW TEST DECK) l w, -
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ENCLOSURE 2 SEQUOYAH NUCLEAR PLANT (SON) - REVISED RESPONSE TO THE NRC FOLLOW-UP REQUEST FOR ADDITIONAL INFORMATION (RAI)
REGARDING GENERIC LETTER (GL) 92-08 l
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DATED DECEMBER 22,1994 J l
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BACKGROUND Since the original response was submitted to NRC, TVA has completed qualification '
testing (i.e., fire, ampacity, and seismic) that addresses TVA Thermo-Lag 330-1 configurations. This testing was documented for Watts Bar Nuclear Plant (WBN)in NUREG-0847, Supplement 18. The scope of the testing was twofold: (1) To prcvide the design bases for the new Thermo-Lag 330-1 installations at WBN, and (2) to provide a qualification basis, or determine acceptable upgrades, for existing installations at other .
TVA nuclear plants (e.g., SON). The detailed test information has been incorporated .
into, and is controlled by, upper tier TVA nuclear documents (i.e., General Engineering i Specification [G Speci and Design Standards (DS]), which all TVA nuclear sites are !
required to use.
Based on results from the TVA Thermo-Lag Fire Test Program, SON will upgrade
.Thermo-Lag 330-1 installation on conduits smaller than three inches, junction boxes, a cable tray, and other applicable unique configurations. Until upgrades are completed, ,
appropriate compensatory measures will remain in place. SON does not expect to upgrade conduits three inches and larger since testing demonstrated that current ,
installations on these conduit sizes are qualified (see Enclosure 1 of this submittal for ,
details). .
In order to resolve the material property discrepancies discovered by TVA in June 1995, !
another full scale, one-hour fire endurance test was necessary. The following response ;
- includes information gained in the January 1996 full-scale fire test and updates !
information previously submitted in the March 22,1995, RAI response.
Thermo-Lag 330-1 MATERIALS ;
NRC Reauest la Describe the specific tests and analyses that will be performed to verify that
, Thermo-Lag 330-1 fire barrier materials that are currently installed at SQN Units 1 and 2, or that will be installed in the future, are representative of the materials that were ;
used to address the technicalissues associated with Thermo-Lag 330-1 barriers and to 1
construct the fire endurance and ampacity derating test specimens. The test and >
I analyses shall address the material properties and attributes that were determined or controlled by Thermal Science incorporated (TSI) during the manufacturing process and t the_ quality assurance program. The test and analyses shall also address the material ,
properties and attributes that contribute to conclusions that Thermo-Lag 330-1 materials and barriers conform to NRC regulations. These include: ;
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- 1. Chemical Composition 2.- Material Thickness -
h 3. Material Weight and Density:
~4.. Presence of Voids, Cracks, and Delaminations
- 5. Fire Endurance Capabilities
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- 6. Combustibility 1 7e Flame Spread Rating -
- 8. Ampacity Derating
- 9. Mechanical Properties Such as Tensile Strength, Compressive Strength, Shear Strength, and Flexural Strength.'
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TVA RESPONSE The following tests and analyses will be performed to provide assurance that Thermo-Lag 330-1 materials and barriers conform to NRC regulations:
L ' Chemical Composition
- TVA has completed extensive chemical composition testing on Thermo-Lag 330-1 materials. Infrared (IR) Spectroscopy and Thermogravimetric Analysis (TGA) were
. performed to verify that Thermo-Lag 330-1 fire barrier materials installed at SON Units 1 and 2 are representative of the materials used in the fire endurance,_
ampacity derating, and seismic tests. IR Spectroscopy was conducted in accordance with TVA procedures derived from American Society for Testing and Materials (ASTM) E 1252-88," Standard Practice for General Techniques for
- Qualitative Infrared Analysis." TGA was performed in accordance with procedures derived from ASTM E 1131-93," Standard Test Method for Compositional Analysis by Thermogravimetry," to the extent practical for the equipment used by TVA.
IR and TGA testing was performed on samples taken from the production lots used to upgrade existing Thermo-Lag 330-1 installations to comply with the TVA tested configurations.
Baseline testing (i.e., IR ar;d TGA analysis) was performed for WBN on samples taken from production lots used for testing. Testing of three lots to verify homogeneity was also conducted at WBN.
In the process of performing the TGA and IR testing for all Thermo-Lag 330-1 materials installed at WBN, lots of New Old Stock (NOS) Thermo-Lag 3301 materials were tested. A discrepancy in the TGA was found in some of the NOS materials. It was also determined that Thermo-Lag 330-1 materials exhibiting this
' discrepancy were installed at SON. TVA notified NRC about the discrepancy by letter dated June 15,1995. In order to resolve this issue, TVA conducted a
' full-scale, one-hour fire endurance test on January 17,1996 (Reference 6). The test consisted of control materials (i.e. materials previously qualified by single-layer i fire testing) and materials exhibiting this anomaly. The testing demonstrated that the NOS material exhibiting this anomaly (i.e., Thermo-Lag 330-1 material currently
' installed at SON) performed equal to or better than the new qualified production l'* materials used extensively throughout the TVA testing program. Accordingly, TVA expanded the acceptance curves for TGA in G-Spec G-98. Based upon the results is of this testing, TVA considers the Chemical Composition issue closed.
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- 2. Material Thickness
.TVA did not manufacture or fabricate any Thermo-Lag 330-1 panels or shapes at SON. Thermo-Lag 3301 material originally procured for SON had a specified minimum thickness of 1/2 inch for a 1-hour fire rating. The testing that was performed to support the WBN Thermo-Lag 3301 testing program had a specified thickness of 5/8 inch plus or minus 1/8 inch. .The requirements for material thickness are identified in G-Spec G 98. SON will perform upgrades to conduits less than 3 inches in diameter to comply with the upgrade requirements of G-Spec G 98. Thickness of upgrade materials will be verified during TVA quality control
. inspections. These upgrade activities will eliminate potential thickness concerns for installed conduits. For conduits with diameters greater than or equal to --
3 inches, no upgrade is required or planned. During the construction of the January 17,1996, full-scale, one-hour fire endurance test assembly, TVA measured and recorded the thickness of all 19 :ots of material used. At least 15 -
lots of material used was SON vintage NOS material. The NOS material thickness was consistently between 1/2-inch to 3/4-inch thick. This further supports TVA
' definition of " Nominal 5/8 inch" material with the tolerance of plus or minus 1/8 inch. Based on this information gathered during the construction of the test
-assembly with SON vintage material, TVA considers this issue closed. ;
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- 3. Material Weight and Density Density acceptance criteria was established based on the results of weighing and ;
measuring samples from the lots used during TVA fire endurance, ampacity derating, and seismic testing. For installation of new Thermo-Lag 330-1 material, a sample from each lot being installed at SON will be measured to ensure that Thermo-Lag 3301 conforms to the density acceptance criteria. Based upon the ,
satisfactory performance of the vintago NOS material used in the January 17,1996, full-scale, one-hour fire endurance test, and the fact that the density of this material was found to meet the G Spec G-98 acceptance requirements, no additional density testing will be required for the existing Thermo-Lag 330-1 material that will remain in place. l i
L Based on lessons learned during installation at WBN, the installed thickness of the ERFBS tends to run on the high side relative to the minimal requirements of G-Spec l 4 G 98. Thus, the weights used for the seismic / structural qualification of the ERFBS will be based on field measurements of representative ERFBS at SON. The density used will be in accordance with Civil Engineering Design Standard DS-C1.6.16.
e 4. Presence of Voids, Cracks, and Delaminations During the upgrade of Thermo-Lag 3301 material for conduits less than 3 inches in
- diameter, G-Spec G 98 will be used as the governing document for acceptable 4
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i configurations G-Spec G-98, " Installation Modification, and Maintenance of-Electrical Raceway Fire Barrier Systems," defines acceptance criteria for voids, cracks, and delaminations as follows:
- 1. Surface voids - Surface voids are unacceptable.
- 2. Cracks - Surf ace cracks that exceed 2 inches in length and 1/16 inch in depth are unacceptable.
.3. Delaminations - No observable separation of materialis allowed, i
$ All upgrades will be inspected to the acceptance criteria provided in G-Spec G-98.
For the existing conduits greater than or equal to 3 inches in diameter that do not require upgrades, the acceptance criteria of G-Spec G 98 will be verified by i inspecting the Thermo-Lag 330-1 ERFBS.
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^TVA will not inspect for internal voids. During qualification testing for WBN, TVA used standard production Thermo-Lag 330-1 materials manufactured and inspected to the TVA specifications and tolerances described above. While preparing the '
material for testing, internal voids were discovered during cutting operations for i installation. The material containing voids was used during testing. No problems resulting from the internal. voids were discovered in any of the single-layer fire tests q l
including the most recent January 17,1996, test. This may be attributed to the d- fact that Thermo Lag 330-1 swells during its sublimation process and closes the l
. internal voids. Therefore, the internal voHs that are inherent in the manufacturing process of the Thermo-Lag 330-1 prefabricabd boards and conduit sections are )
considered to be acceptable, in the construction of the January 17,1996, test assembly, some " worst-case" damaged, cracked, cod delaminated (i.e., the stress e skin separated from the Thermo-Lag material) preformed sections were used. The purpose of using this worst-case material was to demonstrate the acceptability of the material when installed in accordance with TVA procedures. Also, note that the three craftsmen who performed the installation of the ERF8S on the test assembly worked on the original SON installations. No failures occurred during the testing.
1 Additionally, the effect of voids has been adequately considered in the j e
t seismic / structural qualification requirements described in DS-C1.6.16. i
)
- 5. Fire Endurance Capabilities TVA performed two phases of fire testing to demonstrate the fire endurance capabilities of Thermo-Lag 330-1. The first phase of testing consisted of six, single-layer one-hour fire tests for Thermo-Lag 330-1. These tests were submitted to NRC by Reference 3. The second phase of fire testing consisted of seven, full-scale, one-hour fire tests for Thermo-Lag 330-1 and were submitted to NRC by Reference 4. TVA performed an additional full-scale, one-hour fire endurance test !
- _ on January 17,1996, to document the performance of SON vintage NOS materials
- - and installation. -These fourteen fire tests document the fire endurance capabilities of Thermo Lag 330-1 when installed in accordance with TVA procedures. ;
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5-The fire endurance capabilities of Thermo-Lag 330-1 fire barriers are dependant on the materials being used and the manner in which the Thermo-Lag 330-1 material is installed. The material verification measures described earlier ensure that consistent materialis used. The installation procedures governed by TVA's G-Specs and dss ensure that Thermo-Lag 3301 will be installed in an acceptable manner similar to that used during the TVA testing' program. Upgrades to conduits less than three inches will use the upgraded requirements of G-Spec G 98, while the conduits not being upgraded will be evaluated by reviewing samples from the material that is removed during the Thermo-Lag 330-1 reduction program. The methods used for the preparation of the test samples were comparable to those used during SON's originalinstallation. These measures are adequate to ensure that the fire endurance capabilities of Thermo-Lag 330-1 fire barrier assemblies installed at SON are consistent with those used in the fire endurance tests.
~
- 6. Combustibility No combustibility tests or analyses are planned. TVA will define Thermo-Lag 330-1 as a " Combustible." This is based upon the test results described in NRC Information Notice 92-82; Nuclear Utility Management and Resource Council (NUMARC), "Thermo-Lag 330-1 Combustibility Evaluation Methodology Plant Screening Guide," ASTM E136, D1929, E1321, and E1354 test results; and Underwriters Laboratory Inc. (UL) 723 test report, File R6076 Project 81NK3238 dated June 16,1981. The definition has been included in the latest revision of TVA DS-M17.2.2," Electrical Raceway Fire Barrier Systems." The weights of the material used for calculating the combustible loading will be compatible with that used for the seismic / structural qualifications.
SON does not use Thermo-Lag 330-1 as noncombustible radiant energy shields.
Additionally, SON does not use Thermo-Lag 330-1 to create combustible free zones.
l l
- 7. Flame Spread Rating No flame spread rating tests or analyses are planned. Thermo-Lag 330-1 was tested by UL in 1981 (UL test 723 File R6076 Project 81NK3238 dated June 16,1981). UL indicates a flame spread value of 5, fuel contribution value of )
O and smoke developed value of 15. Additional tests were conducted by NUMARC
("Thermo-Lag 330-1 Combustibility Evaluation Methodology Plant Screening l Guide") and ASTM (D1929, E1321, and E1354 test results). NRC has also l conducted flame spread testing and issued their findings in Information l Notice 95-32. TVA has reviewed the results of these tests and established values j for flame spread ratings. They are contained in DS-M17.2.2. j l
- 8. Ampacity Derating TVA performed two phases of ampacity derating tests that are applicable to SON.
The first phase ampacity derating test results (Thermo-Lag 330-1) were submitted l to NRC by Reference 3. WBN has submitted the second phase of 1 Thermo-Lag 3301 ampacity test reports to NRC (Reference 7). l 1
.'y i
1 6-I Ampacity derating associated with a Thermo-Lag 330-1 fire barrier is dependant on -f the materials being used and the manner in which Thermo-Lag 330-1 is installed.
The material verification measures described herein (e.g., chemical testing, weight
- and density measurements) ensure that consistent materialis used. The installation procedures governed by the G-Specs and dss ensure that Thermo-Lag 330-1 used in the plant is installed in the same manner as the Thermo-Lag 330-1 used during testing. These measures are adequate to' ensure f
that the ampacity derating factors used for the Thermo-Lag 330-1 fire barrier l
. materials installed at SON are consistent with the derating factors developed during ,
the ampacity derating tests.
- 9. Mechanical Properties Such as Tensile Strength, Compressive Strength, Shear Strength, and Flexural Strength TVA has performed mechanical property (static) testing of the materials used to ,
construct the TVA Thermo-Lag 330-1 fire barriers. Seismic (static and dynamic) test results were submitted to NRC by Reference 5.
To provide additional assurance of reliable mechanical properties for seismic ,
qualification, board shear strength acceptance criteria has been determined, in accordance with ASTM D.4255, using samples from the lots used in the TVA i testing programs. For installation of new Thermo-Lag 330-1 material as part of the upgrades, a sample from each lot of board material being installed at SON will be tested to ensure that Thermo-Lag 330-1 conforms to the board shear strength acceptance criteria. TVA will evaluate the existing installed Thermo-Lag 330-1 ERFBS that will remain in place, in accordance with the requirements of .
1 DS-C1.6.16, which reflects the results of the extensive material property testing performed by TVA to date. Shear tests performed on existing NOS material demonstrated that it meets the acceptance criteria stated in G-Spec G 98.
Other mechanical properties such as tensile strength, compressive strength, and i flexural stiength do not need to be tested further. In TVA's designs, the stainless l and carbon steel mesh (stress skin) bonded to the Thermo-Lag 330-1 board is the i principal material used to ensure that Thermo-Lag 330-1 remains in place under l postulated design-basis seismic events. Tensile strength, compressive strength, and flexural strength of Thermo-Lag 330-1 depend primarily on the physical ]
properties of the steel mesh. Since steel properties are relatively consistent and not controlled by TSI, no confirmatory test program is needed to establish the -
consistency of those properties.
NRC Reauest 1b -
Describe the methodology that will be used to determine the sample size and <
demonstrate that sample size will be large enough to ensure that the information and j
. data obtained will be sufficient to assess the total population of in-plant 1 Thermo Lag 330-1 barriers and the materials that will be installed in the future. In determining the sample size, consider the time of installation and manufacture of the various in-plant materials and barrier installations. Give the number and types (e.g.,
panels, conduit preshapes, trowel-grade material, stress skin) of samples that will be tested or analyzed.
i .
TVA RESPONSE Based on the successful January 17,1996, full-scale, one-hour fire endurance test and the extensive material property information gained at WBN, TVA considers it sufficient - !
to take a sample from each lot of the new Thermo-Lag 330-1 material that will be used to upgrade or replace Thermo-Lag 330-1 fire barriers at SON. The January 17,1996, full-scale, one-hour fire endurance qualification test was constructed from NOS material presently held at Hartsville, Tennessee. The materials obtained from the Hartsville warehouse were procured at approximately the same time as that installed at SON.
Based on the extensive testing performed, TVA has an established methodology that
- requires sampling of each new lot, but will not require sampling of presently installed -
material.
NRC Reauest - 1c Submit the schedule for verifying the Thermo-Lag 330-1 materials.
TVA RESPONSE TVA's proposed schedule is as shown below:
Based on the successful January 17,1996, single-layer fire test and the extensive material property testing performed by TVA for the completion of WBN, TVA considers .
the material properties issue closed. TVA maintains the requirements for material l property testing for all new lots of Thermo-Lag 330-1 materials used in upgrades in j G-Spec G-98.
NRC Reauest - 1d
'After the analyses and tests have been completed, submit a written supplemental report that confirms that this effort has been completed and provide the results of the tests and analyses. Describe any changes to previously submitted plans or schedules that result from the tests or analyses. -l l
TVA RESPONSE l 1
TVA is providing an updated response with this submittal (see Enclosure 1). This response contains the appropriate information committed to in TVA's letter dated March 22,1995, to NRC.. Schedule changes are discussed in TVA's new response to
- NRC Request 2c.
- i. IMPORTANT BARRIER PARAMETERS ,
l
' NRC Reauest - 2a Describe the cxaminations and inspections that will be performed to obtain the L !important barrier parameters given in Section ll of the RAI of December 21,1993, for the Thermo-Lag 3301 fire barrier configurations installed at SON Units 1 and 2.
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- TVA RESPONSE l r '
Thermo-Lag-330-1 ERFBS installations at SON will ne upgraded, in accordance with l
- G-Spec G 98 and site specific drawings and instructions. Additionally, during the upgrade, existing installations will be verified by physical inspection, where practical. -
l The importance of. variations of Thermo-Lag 330-1 ERFBS parameters has been ]
i determined from TVA's fire endurance, seismic, and ampacity test programs. The !
1 additional information gained by the January 17,1996, single-layer fire testing will also l
. be included. The important design parameters are controlled in TVA dss as follows 1
- 1. DS-M17.2.2, " Electrical Raceway Fire Barrier Systems."
- 2. DS-C1.6.16," Structural Evaluation of Electrical Raceway Fire Barrier Systems."
' 3.' DS-E12.6.3," Auxiliary and Control Power Cable Sizing Up To 15,000 Volts."
l These dss, and the applicable SON design criteria, will be the basis for the site specific . ;
- - drawings and design change documents, which will define the specific upgrades. J J
G-Spec G-98 describes the engineering requirements for installation, modification, and !
- maintenance of ERFBS. It also reflects lessons learned from TVA's fire endurance, seismic, and ampacity test programs, and the WBN/BFN installation experience.
i G-Spec G-98, in addition to the site specific drawings and design change documents, will provide the complete design output for control of the SON Thermo-Lag 330-1 ERFBS upgrades, b The following 32 sections correspond to the specific parameters identified in the December 21,1993, NRC RAl. In each case, a brief description is given of the basis for the associated inspections and examinations to be performed for the SON upgrades, as justified by TVA's testing program and dss. 1 L 1. Raceway Orientation (horizontal, vertical, radial bends)
TVA varied raceway orientation as a part of the fire endurance testing. Typically, i fire test assemblies had the raceway running both horizontally and vertically in the j
', same test. Items used to change direction, such as radial bends and condulets i (lateral bends), were included in the testing. TVA also tested assemblies running l vertical in a wall furnace to ensure our designs were not position dependent. j important fire barrier parameters for different raceway orientations are documented in TVA DS-M17.2.2.
Additionally, TVA considered potential raceway orientations and locations when defining Required Response Spectra (RRS) for seismic qualification tests. TVA DS-C1.6.16 provides the associated methods for seismic qualification. Installation, examination, and inspection will be in accordance with corresponding installation and inspection documents (e.g., G-Spec G-98) and SON site specific drawings of typical enclosures.
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- 2. Conduit TVA varied the sizes of conduits to determine the number of layers and thickness of Thermo-Lag 330-1 required for each size during fire endurance testing. Important fire barrier parameters for conduits are documented in DS-M17.2.2. Installation, examination, and inspection for conduit parameters will be in accordance with corresponding installation and inspection documents.
- 3. Junction Boxes and Lateral Bends TVA performed fire endurance testing on the smaliest and largest anticipated junction boxes and lateral bends expected to be encountered at SON. Important fire barrier parameters are documented in DS-M17.2.2. DS-C1.6.16 provides methods for seismic qualification. Installation, examination, and inspection for junction box and lateral bend parameters will be in accordance with corresponding installation and inspection documents.
- 4. Ladder-back Cable Yray With Single-layer Cable Fill TVA performed a fire endurance test on a ladder-backed cable tray with a single layer of cable fill to compare the results with other amounts of cable fill. Important barrier parametecs for this attribute are documented in DS-M17.2.2. Installation, examination, and inspection for cable fill parameters will be in accordance with corresponding installation and inspection documents.
1
- 5. Cable Tray With T-Section TVA performed a fire endurance test on the largest expected cable tray T-Section. )
Important fire barrier parameters are documented in DS-M17.2.2. DS-C1.6.16 provides associated allowable stresses and analysis methods for seismic qualification. Installation, examination, and inspection for T-section parameters will be in accordance with corresponding installation and inspection documents.
- 6. Raceway Material (Aluminum, Steel)
TVA tests used steel and aluminum conduits. The cable trays used in the fire endurance and seismic testing were steel, which is representative of the cable tray to be protected at SON. Important fire barrier parameters are documented in DS-M17.2.2. DS-C1.6.16 provides associated methods for seismic qualification.
installation, examination, and inspection for raceway material parameters will be in accordance with corresponding installation and inspection documents.
- 7. Support Protection, Thermal Shorts (Penetrating Elements) !
Both phases of the TVA test program included tests using steel supports to determine support protection and thermal short parameters. The supports in the testing were steel, which is representative of the supports to be protected at SON.
Important barrier parameters are documented in DS-M17.2.2. SON raceway supports will be protected such that the supports will retain sufficient strength to ensure raceway functionality during the postulated fire event. Installation, examination, and inspection support protection parameters will be in accordance
.with corresponding installation and inspection documents.
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- 8. Air Drops TVA tests included air-drop cables to determine their protection parameters. As previously reported in Reference 1, SON has one cable air-drop fire barrier installed inside a pull box in the 480-volt shutdown transformer room on Elevation 749 of the e, auxiliary building. This configuration was installed because of support problems ;
associated with the protection of the pull box. TVA now has a tested and qualified 3
- junction box fire barrier configuration that involves a free-standing frame that will not add load to the box.
- 9. Baseline Fire Barrier Panel Thickness Baseline fire barrier panel thickness tolerances were determined prior to the construction of the test assemblies. TVA has defined the thickness as nominal 3/8 and 5/8 inch. The tolerances for these nominal sizes of materials are plus or minus 1/8 inch. This requirement corresponds to the Thermo-Lag 330-1 material -
used in the TVA testing. This barrier parameter will be verified during inspections at SON. New materials will comply with G-Spec G-98. !
- 10. Preformed Conduit Panels Baseline preformed conduit fire barrier panel thickness tolerances were determined l prior to the construction of TVA's test assemblies. TVA has defined the thickness :
1 as nominal 3/8 and 5/8 inch. The tolerances for these nominal sizes of materia!s i
are plus or minus 1/8 inch. This requirement corresponds to the Thermo-Lag 330- l 1 material used in the TVA testing program. This tolerance was reconfirmed during j
' the construction of the January 17,1996, single-layer fire endurance test assembly.
- 11. Panel Rib Orientation Panel rib orientation is not considered to be a critical attribute since seismic and fire endurance qualification did not rely on the presence of panel ribs.
- 12. Unsupported Spans TVA evaluates and seismically qualifies each SON Thermo-Lag 330-1 installation unsupported span in accordance with DS-C1.6.16. Typical qualified unsupported span configurations are to be shown on SON site specific drawings.
- 13. Stress Skin Orientation (Inside or Outside)
~
4 Standard production Thermo-Lag 330-1 boards and preformed conduit sections are manufactured with internal stress skin. In addition to the internal stress skin,' a number of SON design upgrades will use external stress skin. External stress skin E is an important parameter for fire endurance and seismic qualification. The designs ,
specifying stress skin orientation will be documented in DS-M17.2.2 and l l
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SON site specific drawings. For installat;ons that will be upgraded at SON, the l installation, examination, and inspection for stress skin orientation parameters will i be in accordance with corresponding installation and inspection documents. [
- 14. Stress Skin Over Joints or No Stress Skin Over' Joints ;
TVA fire tested a number of external applications of stress skin that could be used as upgrades at SON. .The designs specifying stress skin orientation will be J documented in DS-M17.2.2 and SON site specific drawings. For installations that will be upgraded at SON, the installation, examination, and inspection for stress
. skin over joints parameters will be in accordance with corresponding installation l and inspection documents. <
- r
.15. Stms Skin Ties or No Stress Skin Ties
- TVA tested a number of designs using stress skin ties (stitching) that could be j ~ used as upgrades at SON. The designs specifying stress skin tie placement are documented in DS-M17.2.2. ' installation, examination, and inspection of stress :
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- documents.
- 16. Dry-fit, Postbuttered Joints or Prebuttered Joints y J
TVA design and testing uses complete prebuttered joints. This fire barrier parameter will be documented in DS-M17.2.2 and SON site specific drawings.
installation, examination, and inspection for buttered joints will be in accordance with corresponding installation and inspection documents.
- 17. Joint Gap Width &
Joint gap width is specified in DS-M17.2.2. Installation, examination, and '
inspection for joint gap widths will be in accordance with corresponding installation
[ and inspection documents.
- 18. Butt Joints or Grooved and Scored Joints TVA's fire endurance testing program tested a number of designs using both butt ;
joints and grooved and scored (score and fold) joints. - The designs specifying the type of joint will be documented in DS-M17.2.2 and site specific drawings.
Installation, examination, and inspection for joints will be in accordance with corresponding installation and inspection documents.
a L19. Steel Bands or Wire Ties
'One-hour fire barrier systems at SON will use tie wires and/or bands where
. qualified 'per DS-M17.2.2 and DS-C1.6.16. The designs specifying this barrier .
-parameter will be documented in DS-M17.2.2 and SON site specific drawings.
The presence of tie wires or steel bands is an important parameter for seismic qualification of enclosures requiring them, Installation, examination, and inspection for tie wire / band parameters will be in accordance with corresponding installation and inspection documents.
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- 20. Band / Wire Spacing Band or tie wire spacing requirements were determined by TVA fire endurance testing and seismic' qualification evaluations. The designs specifying band or tie wire spacing will be documented in DS-M17.2.2 and SON site-specific drawings.
Approximate band or tie wire placement is a significant parameter for seismic l qualification of the enclosures requiring them and is addressed in DS-C1.6.16.
Installation, examination, and inspection for tie wire / band parameters will be in accordance with corresponding installation and inspection documents.
- 21. Band / Wire Distance to Joints Band or tie wire distance from joint requirements were determined in the TVA testing. The designs specifying wire distance to joints will be documented in DS-M17.2.2 and SON site specific drawings. Band or tie wire placement from jo'ints is a significant parameter for seismic qualification of the enclosures and is addressed in DS-C1.6.16. Installation, examination, and inspection for bsnd of tie wire parameters will be in accordance with corresponding installation and inspection documents.
- 22. No Internal Bands in Trays Internal bands will not be used inside SON cable trays. The cable tray design will be evaluated in accordance with DS-M17.2.2. Installation, examination, and inspection for internal tie wires will be in accordance with corresponding installation and inspection documents.
l l 23. No Additional Trowel Material Over Sections and Joints or Additional Trowel l
Material Applied TVA installations at SON used additional trowel grade in the finishing process over sections and joints. The designs specifying use of trowel grade material are acceptable as documented in DS-M17.2.2. Installation, examination, and inspection for added trowel grade material will be in accordance with corresponding installation and inspection documents.
- 24. No Edge Guards or Edge Guards Stainless steel edge guards will remain at SQN where qualified per DS-M17.2.2 and DS-C1,6.16. Examination and inspection will be performed to ensure proper installation in accordance with corresponding inspection documents.
- 25. Cable Size and Type (Power, Control, or Instrumentation)
Cable size and type are not considered to be critical attributes because the TVA _
designs used at SON meet the 250-degree F average temperature rise /325-degree F maximum temperature rise acceptance criteria provided in Supplement 1 to GL S6-10. The January 17,1996 TVA fire test constructed with-
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SON vintage Thermo-Lag 330-1 materials and conducted at Omega Point l Laboratories, documents temperatures measured on the exterior of the 3-inch conduit and the bare #8 AWG wire installed in 3-inch conduits also meet the i 250-degrees F average temperature rise /325-degrees F maximum temperature rise
! acceptance criteria provided in Supplement 1 to GL 86-10.
I I Cable size and type is a consideration when determining the effects of ampacity qualification. Ampacity derating factors are assigned depending on the type of Thermo Lag 330-1 enclosure used. TVA design control measures ensure that the
! appropriate ampacity derating factor is used where a Thermo-Lag 330-1 enclosure is specified.
I l
- 26. Cable Jacket Type (Thermoplastic, Thermoset) and Materials Cable jacket type is not considered to be a critical attribute since the TVA designs l used at SON will meet the 250-degree F average temperature rise /325-degree F maximum temperature rise acceptance criteria provided in Supplement 1 to l GL 86-10. Therefore, no examinations or inspections are needed to identify cable l Jacket type.
- 27. Cable Conductor Insulation Type (Thermoplastic, Thermoset Plastic) and Materials Cable insulation type is not considered to be a critical attribute because the designs used at SON shall meet the 250-degree F average temperature rise /325-degree F maximum temperature rise acceptance criteria provided in Supplement 1 to GL 86-10. Theiefore, no examinations or inspections are needed to identify cable
~ insulation type.
- 28. Cable Fill and Distribution of Cables Within the Protected Conduit or Cable Tray in conduits, cable fill and distribution are not considered to be critical attributes because the designs used at SON will meet the 250-degree F average temperature l rise /325-degree F maximum temperature rise acceptance criteria provided in Supplement 1 to GL 86-10. TVA testing to establish the acceptable designs was performed with no cables installed. Installed cable willincrease the interior thermal mass and result in improved performance (i.e., inside temperatures will be lower than those which occurred during the tests). Therefore, no examinations or inspections are needed to identify cable fill and distribution in conduits.
In cable trays, TVA determined that a minimum mass of 1.33 pounds-per-linear foot must be present in the cable tray to meet the 250-degree F average temperature rise /325-degree F maximum temperature rise acceptance criteria l provided in Supplement 1 to GL 86-10. Where insufficient mass exists, additional !
cable is installed to meet the mass requirements specified in TVA designs, l Minimum mass requirements are specified in DS-M17.2.2. Installation, ]
examination, and inspection will be in accordance with corresponding installation ;
and inspection documents.
]
Seismic qualification is based on a predetermined cable weight. Cable fill and cable weight is tracked and maintained in the SON Consolidated Cable Routing System (CCRS) database and is considered when evaluating the seismic adequacy by DS-C1.6.16.
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- 29. Proximity'of Cables to the Unexposed (Inside) Surfaces of the Fire Barrier.
Cable proximity to the surface of the fire barrier is not considered to be a critical attribute at SON. Cables in cable trays and conduits do not come into contact with the fire barrier. Therefore, no examinations or inspections are needed to identify cable proximity to the fire barrier. ;
- 30. Presence of Materials Between ti.e Cables and the Unexposed Side of the Fire
-Barrier Material (for example, seaftemp cloth, which is used in the NUMARC test specimens).
- Material presence is not considered to be a critical attribute because the TVA j designs used at SON will meet the 250-degree F average temperature !
rise /325-degree F maximum temperature rise acceptance criteria provided in Supplement 1 to GL 86-10 without specifying additional material. Therefore, nc examinations or inspections are needed to ensure the presence of additional materials. It should be noted that many cables at SON have been coated with the fire retardant "Flamemastic." This coating was applied before the Appendix R requirements were promulgated, and no credit is taken for its presence.
1
- 31. Cable Operating Temperature )
l Cable operating temperature is not considered to be a critical attribute because the i designs used at SON will meet the 250-degree F average temperature i rise /325-degree F maximum temperature rise criteria provided in Supplement 1 to i
.GL 86-10. As a result of their insignificant loading, control and instrumentation I cables are assumed to be operating at the maximum normal ambient temperature ]
for their respective environments. Therefore, no examinations or inspections are needed to identify the cable operating temperature.
- 32. Temperatures at Which the Cables Can No Longer Perform Their intended Function When Energized at Rated Voltage and Current Those temperatures are not considered to be a critical attribute because the designs used at SON will meet the 250-degree F average temperature rise /325-degree F maximum temperature rise criteria provided in Supplement 1 to GL 86-10. Therefore, no examinations or inspections are needed to identify the temperatures at which cables can no longer perform their intended function when energized at rated voltage and current.
NRC Reauest - 2b-Describe the methodology that will be applied to determine the number and type of representative in-plant fire barrier configurations that will be examined in detail and demonstrate that the sample size is adequate to ensure that the information and data that.will be obtained are adequate to assess the total population of in-plant Thermo-Lag barriers. A large enough sample of the total population of configurations should be .
examined to provide reasonable assurance that the materials and important barrier parameters used to construct the in-plant barriers and any future barrier installations or modifications, are representative of the parameters used to construct the fire endurance test specimens.
--_ .--_=_-__________-___-________-_____--____-_-___ _-
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TVA RESPONSE As previously discussed in TVA's response to item 1c above, the materials property issue is closed and no sampling of existing installed material will be performed. SON will be performing upgrades on conduit less than three inches in diameter and other unique configurations. These upgrades will be performed in accordance with G-Spec G-98. SON does not expect to be performing upgrades to conduits with three inch and greater diameters since testing performed by TVA has qualified these installations. Since installation documentation does not exist pertaining to important barrier parameters used to construct the presently installed Thermo-Lag 330-1, TVA will be performing walkdowns to verify and document these installations. Allinstailations, where practical, will be visually inspected. This will provide a sample size of almost all the installed Thermo-Lag 3301 at SON.
NRC Reauest - 2c Submit the schedule for obtaining and verifying all of the important barrier parameters.
TVA RESPONSE TVA will perform the field walkdowns and evaluations of the important barrier parameters of ti e existing Thermo-Lag 330-1 ERFBS by October 1,1997. The walkdowns and evaluations will be performed in accordance with the criteria described in TVA's response to NRC Request - 2a.
NRC Reauest - 2d i
After the information has been obtained and verified, submit a written supplemental I report that confirms that this effort has been completed and provides the results of the examinations and inspections. Verify that the parameters of the in-plant configurations are representative of the parameters of the fire endurance test specimens. Describe any changes to previously submitted plans or schedules that result from the examinations.
TVA RESPONSE TVA will submit a supplemental report providing the requested information for Request - 2d by January 14,2000.
Commitments contained in this letter supersede all previous commitments pertaining to
.this subject.
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16 - l
'y i References TVA letter to NRC dated April 15,1993, "Sequoyah Nuclear Plant (SON) - Generic
~
- 1. l
- Letter (GL) 92 Thermo-Lag 330-1 Fire Barriers"
- 2. TVA letter to NRC dated February 10,1994, "Sequoyah Nuclear Plant (SON) -
Request for Additional Informaticn Regarding Generic Letter 92-08,'Thermo-Lag . l
' 330-1 Fire Barriers,' Pursuant to 10 CFR 50.54(f)- Sequoyah Nuclear Plant, ,
i
- - Units 1 and 2 (TAC Nos. M85604 and M85605)"
i
- of Qualification Testing for Thermo-Lag 330 Fire Barriers (TAC M63648)" i
- 0 Response to NRC Questions Regarding the Use of Thermo-Lag Fire Barrier Systems i j_ at WBN (TAC M63648)" ,
i
i Response to NRC Request for Additional Information Related to Thermo-Lag Fire ,
Barrier Assembly Seismic Capabilities (TAC M61648)" j
- 6. Omega Point Laboratories' Test Report, " Fire Endurance Test of Thermo-Lag 330-1
< Fire Protective Envelopes (1 inch,3-inch, and 4-inch Diameter Aluminum Conduits) ,
Project No. 11210-98892" dated February 9,1996.
l 7. TVA letter to NRC dated April 25,1995," Watts Bar Nu:: lear Plant (WBN) - Results !
of Phase 2 Ampacity Testing For Thermo-Lag Fire barriers (TAC M63648)"
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, i I1 ENCLOSURE 3 ,
i Commitments Commitments contained in this letter supersede all previous commitments pertaining to ,
this subject.- !
'1. . Based on results from the TVA Thermo-Lag test program, SON will upgrade ~
. Thermo-Lag 330-1 installation on conduits smaller than three inches, junction i i
boxes, a cable tray, and other applicable unicue configurations, included in the j upgrade program will bs the revision to the appropriate design standards and 3 documents prior to initiation of design activities. TVA will perform the field i
- - walkdowns and evaluations of the important barrier parameters of the existing '
s Thermo-Lag 330-1 Electrical Raceway Fire Barrier System. The walkdowns, i evaluations, and modifications will be performed in accordance with the criteria' ;
i described in TVA's response to NRC Request - 2a. The walkdowns, evaluations, l and upgrades necessary to resolve the Thermo-Lag issue will be completed by October 1,1999. Until upgrades are completed, appropriate compensatory measures will remain in place. :
?
l 2. TVA will submit a supplemental report pre Ming the requested information for }
4' Request - 2d by January 14,2000. l'
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