ML20087G226
| ML20087G226 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 03/29/1995 |
| From: | Graesser K COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| BYRON-95-5033, GL-92-08, GL-92-8, NUDOCS 9504040017 | |
| Download: ML20087G226 (5) | |
Text
r Commonw rahh Idiwn Company
.15yron Generating $tation 1 MO Nonh German Chmth Itoad
' flyron, IL 61nl49791 Tel 815-23 4-$ 14 l March 29,1995 LTR:
BYRON 95-5033 FILE:
1.10.0101 U.S. Nuclear Regulatory Commission Washington, DC 20555 Attention:
Document Control Desk
SUBJECT:
Byron Station Units 1 and 2 Byron Station Response: " Request for AdditionalInformation Regarding Generic -
Letter 92-08, "Thermo-Lag Fire Barriers" Pursuant to 10CFR50.54(f)"
REFERENCES:
NRC Dockets 50-454 and 50-455 1)
USNRC Generic Letter 92-08, "Thermo-Lag Fire Barriers" 2)
USNRC Letter to D. L. Farrar dated December 29,1994, " Followup to the Request for Additional Information Regarding Generic Letter 92-08, issued Pursuant to 10CFR50.54(f), Byron Nuclear Power Station" The purpose of this letter is to provide Byron Station response to the Nuclear Regulatory Commission's Requests for Additional Information pursuant to 10CFR50.54(f) dated December 29, 1994 for those nuclear plants relying on Thermo-Lag 330-01 as Fire Protection Barriers.
This submittal provides information about the planned disposition of Thermo-Lag at Byron Station. Existing Thermo-Lag will be abandoned-in-place and no credit will be taken for it as a fire barrier. Byron Station is reevaluating previously selected barrier solutions. Rerouting of cab!es is being reconsidered as a solution in many instances. Byron will provide a final listing of the solutions being applied to each cable and any schedule revisions in September,1995, as was previously stated in the Comed response dated December 16,1994.
To the best of my knowledge and belief, the statements contained in this document are true and correct. In some respects these statements are not based on my personal knowledge, but on information furnished by other Comed employees, contractor employees, and/or consultants. Such information has been reviewed in accordance with company practice, and I believe it to be reliable.
Sincer ly,
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STATE OF ILLINOIS
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MI COUNTY OF OGLE
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Kenneth L. Graesser Subscribed & sworn to before me Site Vice President Byron Nuclear Power Station this 29th day March, 1995.
M1 cc:
J. Martin, Regional Administrator-Rill R. Capra, Director of Directorate ill-2, NRR
$ tary Public G. Dick, Project Manager, Byron, NRR H. Peterson, Senior Resident inspector (Byron)
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.,1 Byron' Station Response to the "NRC' Request-for Additional-Inforanation'regarding Generic. Letter 92-08,
'Thermo-Lag 330-1. Fire. Barriers',.
Pursuant to 10CFR50.54(f)"
1.
Thermo-Lag Materials Describe the specipe tests and analyses that will be performed to venjy that a.
the Thermo-Lagpre barrier materials that are currently installed at Byron :..
Station (Byron), or that will be installed in thefuture, are representative of the materials that were used to address the technical issues associated with I Thermo-Lag barriers and to construct thepre endurance and ampacity derating test specimens. The tests and analyses shall address the material properties and attributes that were determined or controlled by TSI during the manufacturing process and the quality assurance program. The tests and analyses shall also address the materialproperties and attributes that contribute to conclusions that the Thermo-lag materials and barriers conform.
to NRC regulations. These include:
(1) chemical composition (2) material thickness.
(3) material weight and density (4) the presence of voids, cracks, and delaminations (5) pre endurance capabilities (6) combustibility (7) fame spread rating (8).ampacity derating (9) mechanicalproperties such as tensile strength, compressive strength, shear strength, andpexural strength.'
b.
Describe the methodology that will be used to determine the sample size and demonstrate that the sample size will be large enough to ensure that the information and data obtained will be suficient to assess the totalpopulation ofin-plant Thermo-Lag barriers and the materials that will be installed in the future. In determining the sample size, consider the time ofinstallation 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.
c.
Submit the schedulefor venfying the Thermo-Lag materials d.
After the analysis and tests have been completed, submit a written 1
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' supplemental repon that conprms that this efort has been completed and ~
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. provide the results of the tests and analyses. Describe any changes to previously submittedplans or schedules that resultfrom the tests or analyses.
.i 2.
Important Barrier Parameters a.
Describe the examinations and inspections that will be performed to obtain the j
important barrierparameters given in Section 11 of the RAI of December 1993
. for the Thermo-Lagpre barrier confgurations installed at Byron.
b.
Describe the methodology that will be applied to determine the number and type of representative in-plantpre barrier confgurations 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 ofin-plant Thermo-Lag barriers. A large enough sample'of the
- totalpopulation of confgurations should be examined to provide reasonable.
'i assurance that the materials and important barrierparameters used to i
construct the in-plant barriers and anyfuture barrier installations or q
1 modtfications, are representative of the parameters used to construct thepre endurance test specimens.
l c.
Submit the schedulefor obtaining and venfying all of the imponant barrier n
parameters.
i d.
After the infonnation has been obtained and venped, submit a written supplemental report that conprms that this efort has been completed and provides the results of the examinations and inspections. Venfy that the l
parameters of the in-plant confgurations are representative of the parameters of thefire endurance test specimens. Describe any changes to previously l
submittedplans or schedules that resultfrom the examinations.
RESPONSE
In Byron Station's response dated December 16,1994, a plan and schedule for the resolution of the Thermo-Lag issue at Byron was provided. This plan utilized four of-nine available options for restoring required fire protection to electrical cables. These four options included:
1.
Reanalyzing the Fire Protection Report Safe Shutdown Analysis; 2.
Replacing the installed Thermo-Lag fire barrier with Darmatt KM-1 material;
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3.
Developing Appendix R Exemption requests where sufficient justification exists; 2
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4.
Downgrade an existing 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> barrier to a 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> rating.
The scope of the plan included cable trays and conduits in all fire zones, except Zone 11.5-0, requiring fire protection per the Byron Safe Shutdown Analysis. Each conduit or tray configuration was individually evaluated to identify the best option based on technical acceptability and economics.
r Option 4 (Downgrade) is no longer being pursued at Byron. None of the three remaining selected options involve taking credit for existing or newly-installed Thermo-Lag material as a fire barrier. Options 1 and 3 require documenting technical justification that eliminates the need for fire wrap on the cable trays and conduits.
For both options, the existing Thermo-Lag material would be abandoned-in-place.
Option 2 involves removal of the existing Thermo-Lag material and replacing it with a Darmatt KM-1 material qualified to meet the 1 or 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> fire barrier requirements.
No credit will be taken for the Thermo-Lag material abandoned-in-place as a fire barrier. Only those material properties and barrier parameters important to its abandonment must be assessed. Byron Station considers those material properties to be " combustibility" and "ampacity derating". There are no other barrier parameters of Thermo-Lag pertinent to leaving it abandoned-in-place.
Combustibility of Thermo-Lag material abandoned-in-place has been established through NEl testing. Byron will incorporate the appropriate values of combustibility into the fire hazards analyses for fire zones where the Thermo-Lag material is abandoned. No additional combustibility testing is planned at this time.
Ampacity derating concerns were addressed in the December 16,1994 submittal and established by the methods described in previous responses. The original Thermo-Lag design for Byron used an analytical method to evaluate ampacity derating.
Deratings generated with this method have been shown to be conservative compared to actual ampadty test results. At this time, no additional ampacity testing is planned for the nbandoned Thermo-Lag material.
In late 1994, Byron and Braidwood Stations began reevaluating the corrective actions planned for the cable trays and conduit configurations in Fire Zone 11.5-0. The purpose of the reevaluation was to determine the feasibility of rerouting the affected safe-shutdown cables to eliminate the need for fire-rated barriers. Experience from installation of DARMATT in 1994 showed initial cost projections were low. Therefore, the reevaluation (of rerouting versus replacing) was expanded to include all fire zones containing Thermo-Lag. A detailed cost comparison between the cable rerouting and Darmatt installation is in progress. The advantages of cable rerouting, as compared to Darmatt installation, include the elimination of the fire endurance test program and the need to dispose of the existing Thermo-Lag material as radwaste.
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1 The reevaluation project has started and the preliminary estimates show that the cost -
for cable rerouting is favorable to the revised cost for Darmatt installation. These estimates are currently being refined and work schedules are being developed.
Byron will provide a specific listing of the solutions being applied to each cable and any schedule revisions in September 1995, as was stated in the previous Comed response dated December 16,1994.
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