IR 05000445/1993034
| ML20056G760 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 08/27/1993 |
| From: | Constable G NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| Shared Package | |
| ML20056G756 | List: |
| References | |
| 50-445-93-34, 50-446-93-34, NUDOCS 9309070133 | |
| Download: ML20056G760 (6) | |
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APPENDIX
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t U.S. NUCLEAR REGULATORY COMMISSION
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REGION IV
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. Inspection Report:
50-445/93-34 i
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50-446/93-34 l
Licenses: NPF-87 NPF-89 i
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Licensee: TU Electric
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Skyway Tower l
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400 North Olive Street, L.B. 81
Dallas, Texas Facility Name:
Comanche Peak Steam Electric Station, Units 1 and 2, (CPSES)
l Inspection At:. Omega Point Laboratories, San Antonio, Texas
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Inspection Conducted: August 16-17, 1993
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I Inspector:
M. E. Murphy, Reactor Inspector, Plant Support Section
Division of Reactor Safety Appro
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(G. L. Constable, Chief Plant Support Section Dale i
)ivision of Reactor Safety
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Inspection Summary
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Areas Inspected (Unit'l):
Routine, announced inspection of Thermo-Lag fire
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tests.
Areas Inspected (Unit 21: No inspection of Unit 2 was performed.
-Results (Unit 1):
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Test of Scheme No.11-4 apparently failed, when the fire barrier opened
up during the hose stream test, exposing the cable tray and cables on r
the bottom tray.
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Test of Scheme No.15-2 was an apparent partial pass. One method of
- i Thermo-Lag flexi-blanket installation failed when the cable jacket was charred for about 3 to 4 feet, although no fire barrier burn-through was
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noted and the cable function was not' affected.
i The licensee plans to address the apparent excessive moisture in the e-flexi-blanket wrap used. for Scheme No.15-2.
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9309070133 930830-
_PDR ADOCK 05000445
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The licensee plans to evaluate the potential effect on the test results
of excessive moisture in the power cable used for all of the test
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configurations.
Results (Unit 2): Not applicable.
Sumary of Inspection Findinos:
Inspection Followup Item 50-445/9334-01 was opened (Section 1.4).
- Attachment:
Attachment - Persons Contacted and Exit Meeting
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-3-DETAILS
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1 THERMO-LAG FIRE BARRIER FIRE TEST INSPECTION (64100)
The objectives of this. inspection were to compare the licensee's test configurations and construction detail to requirements specified in the installation procedure; verify location of thermocouples; observe that the oven and test rig' temperatures met the specified test criteria; observe the
application of the proper spray angle, pressure, and flow rate during the fire hose test; and observe post fire cable checks and test specimen disassembly to verify no burn-through ~ or cable damage. The approved acceptance criteria are contained in the licensee's letter logged TXX-92466 dated September 24, 1992, and an NRC letter to the licensee dated October 29, 1992.
i 1.1 Backcround
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The. licensee took the lead in resolving industry Thermo-Lag issues in order to support a NRC decision to issue an operating license for Comanche Peak Unit 2.
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As a result of licensee sponsored fire tests at an independent testing facility the licensee was able to complete both qualified upgrades on installed configurations and initial configuration installations in Unit 2 prior to the issuance of the operating license.
This allowed the commencement
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of operations of Unit.2 without any required fire watches to monitor Thermo-Lag installations in Unit 2.
Since Unit I was in operation before the discovery of the Thermo-lag problem, the licensee has complied with the requirements of NRC Bulletin 92-01 Supplement 1, and has in place the required fire watches as a compensatory measure. The licensee, in continuation of-the program to resolve any
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questionable configurations presently installed in Unit 1, planned to conduct i
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fire tests of five test schemes in mid-August 1993. These schemes were designed to provide approved upgrade techniques for Unit 1 installations.
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tests were conducted at Omega Point Laboratories in San Antonio, Texas, an independent testing facility. Three of the schemes were tested during the week of August'9, 1993, and were observed by an NRC representative from headquarters. The remaining two tests were conducted on August 16 and 17, 1993, and were the subjects of this inspection.
1.2 Construction Construction of the test schemes was performed by CPSES employees during the period of July 18-30, 1993. Observation of the fabrication of the test specimens was conducted by NRC representatives from headquarters and documented in two trip reports dated August 6 and 16, 1993, respectively. The observers compared the licensee's normal fabrication procedures to the actual construction techniques and reported no problems.
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I 1.3 Testino J
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The'two tests observed by the inspector during this inspection were designated by the licensee as Scheme No. 11-4 and No. 15-2.
Scheme No. 11-4 tested a box
' configuration that enclosed cable airdrops from embedded wall sleeves into two stacked 24" x 4" ladder back trays. The remainder of the cable trays not included within the box coverage were protected by normal Thermo-Lag fire l
barrier, upgraded with a layer of stress skin and trowel grade-Thermo-Lag material reinforcing the vertical and bottom butt joints ~. The inspector had
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inspected, during a previous inspection, the same installed configuration in
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the plant' and verified that the test assembly was representative of the actual l
installation. Scheme-No. 15-2 tested Thermo-Lag 330-660 flexi-blanket wrapped
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i cables in a bare, exposed cable tray.
Each cable was wrapped in two layers of j
L the flexi-blanket, one banded with tie wraps, the other with banding. A bundle of three cables was wrapped-in siltemp material and placed in the
. center of the tray between the protected cables. This was done to duplicate l
actual plant installations.
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- 1,3. I' Test of Scheme No. 11-4
.The test commenced at 2243 on August 16, 1993. The ambient temperature was 92*F.
Thirty minutes into the test, no maximum temperatures in the air drop area had exceeded 200*F. At the end of the test, all temperatures were l
uniform, with. a maximum rail temperature of 312*F 'and a maximum cable
. temperature of 297aF. The' test scheme was subjected to the required hose
' stream' by laboratory personnel. The hose' stream was applied from an adjustable 1 1/2" hose nozzle set at approximately 30 degrees from'a distance i
of 5 feet, with.a flow of 75 gpm at 75 psig. There was an installed
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calibrated pressure gauge at the hose nozzle, and the calculated nozzle flow for 75 psig was 75 gpm.
During the hose stream test, a sagging section of stress skin under the middle of the bottom tray allowed peel back and erosion of the base Thermo-Lag, l
. exposing the cable tray and cable in this area. The cable megger readings L
were satisfactory. Subsequent dissection of the assembly revealed no evidence of-burn-through or cable damage. There was some swelling or ballooning of the power cable jacket in the' vertical runs of the bottom cable tray.
The ballooning phenomenon had been noted during the earlier test of-Scheme No; 11-5. ' There was speculation by licensee representatives that this may have been caused by moisture in the cable from a long period of exposure to the. elements, since this particular reel had been stored in the open for a long; period without.any protection. The installation was conducive to this effect since the cable.was tightly banded by cable wraps, preventing any venting of moisture during the heatup and subsequent test.
1.3.2 Test of Scheme No. 15-2 The test commenced at 2059 on August 17, 1993. The ambient temperature was 92*F.
During the first five minutes of the test, the center unprotected cable i
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bundle began discharging a significant amount of hot water and steam.
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was the same No. 6 gauge, 3 conductor power cable that had evidenced jacket l
ballooning during previous tests.
Thirty minutes into the test, temperatures were nominal and increasing at the I
expected rate. There were no indicated hot spots. The center bundle r
continued to discharge a small quantity of fluid, and the front protected
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cable had begun to show evidence of steam and fluid discharge. This i
L discharge, however, was from between the cable and the flexi-blanket wrap, not i
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from within the cable itself.
Forty minutes into'the test, the front protected bundle was still discharging
. steam and fluid. The rear protected bundle had begun to discharge steam and
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fluid also. At.the end of the 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> test,. both bundles were discharging much
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l larger quantities.of steam and fluid.
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I Laboratory-personnel' conducted the hose stream test, using the appropriate l
nozzle setting and discharge pressure.
Visual inspection of the assembly
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disclosed.no damage. to the barrier material and no indications of burn-
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through.. The cable megger tests were satisfactory.
Post test dissection of the assembly confirmed that there was no burn-through; however, there was a
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section of about 3 to 4 feet of apparent heat-affected cable jacket on the front cable. A review of the raw temperature data for this section of cable j
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did not disclose any unusual heating or hot spots. A licensee representative speculated that the difference in barrier wrap may account for the damage.
l 1.4 Conclusions l
l Test of Scheme No.11-4 apparently failed when the fire barrier opened up l-during the hose stream test, exposing the cable tray and cables on the bottom I
tray. Test of Scheme No.15-2 was an apparent partial pass. One method of Thermo-Lag flexi-blanket installation failed when the cable jacket was charred
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for;about 3 to 4 feet, although no-fire barrier burn-through was noted, and the cable function was not affected.
' Final overall conclusions cannot be made until the licensee completes their i
formal report. However, the licensee stated that they would address, in their I
final' report, certain observed conditions that ce ld affect the acceptability of the tests. These-are:
(1) the effect of the moisture contained in some of
.the test cables on cable bundle temperatures, and the tray heat load l
characteristics; (2) the effect of the high moisture content in the flexi-blanket material on the overall test results and the consequences to the
. protected cables if this moisture could not vent and caused a rupture in the barrier; (3)- the cause of the localized heat-affected areas on the single cable in Scheme No.15-2. The licensee's response to the observed conditions and the potential test affect will be considered an inspection followup item pending completion of the licensee's report and review and approval by the j
Office:of Nuclear Reactor Regulation (Inspection Followup Item 445/9334-01).
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ATTACHMENT i
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L 1.-PERSONS CONTACTED l
licensee
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l 0. Bhatty, TU Electric Licensing l
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G. Beckett, TU Electric Engineering.
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F. Madden, TU Electric Engineering i
l C. Pruett, TU Electric' Quality Assurance (Fluor Daniel)
i R. Dible, ABB 'Impell i
.C.. Banning, ABB Impell l
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Omega Point Laboratory i
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l D. Priest, President l
C. Humphrey, Vice President and Quality' Assurance Manager i
.In addition _to the personnel listed above, the inspector contacted other
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personnel during this inspection period.
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2 EXIT MEETING
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A telephone exit was conducted with Mr. Obaid Bhatty on August 24, 1993. The i
inspector reviewed the scope and findings of the inspection. The licensee did
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not identify as proprietary any information provided to, or reviewed by, the inspector.
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