ML20034D517
| ML20034D517 | |
| Person / Time | |
|---|---|
| Issue date: | 12/22/1992 |
| From: | Russell W Office of Nuclear Reactor Regulation |
| To: | Rasin W NUCLEAR ENERGY INSTITUTE (FORMERLY NUCLEAR MGMT & |
| References | |
| IEIN-92-081, IEIN-92-81, NUDOCS 9301050208 | |
| Download: ML20034D517 (5) | |
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NUCLEAR REGULATORY COMMISSION i E WAF,HINGTON, D. C. 20555 py[/
ss-a December 22, 1992
'% '.V Mr. William Rasin Vice President and Director Technical Division Nuclear Management and Resources Council 1776 Eye Street, NW Suite 300 Washington, DC 20006-2496
Dear Mr. Rasin:
The purpose of this letter is to notify you of a potential deficiency in the environmental qualification of electrical cables with bonded jackets. The concerns of the U.S. Nuclear Regulatory Commission (NRC) regarding the qualification of bonded-jacket electrical cables are discussed in NRC Information Notice (IN) 92-81, " Failure of Electrical Cables with Bonded Hypalon Jackets," which is enclosed.
As stated in the IN, the potential deficiency was identified as the result of testing conducted for the NRC by Sandia National Laboratories. On the basis of test results for the electrical cables with Hypalon bonded jackets and the ensuing evaluations of available data, the NRC has concluded that Hypalon and other bonded-jacket cables in safety-related applications may be susceptible to failure when installed service conditions exceed temperatures of 50 *C (122' F) for 40 years.
While the NRC believes there is no immediate safety concern, the staff is evaluating the extent of this potential deficiency and developing actions necessary to resolve this issue. The staff is considering a Generic Letter as a means to gather information required to ascertain the long-term safety significance of this issue. The information needed includes:
the quantity of bonded-jacket cables being used in safety-related applications; the environmental qualification status of these cables; the actual service conditions of the cables; and the material condition of the installed cables.
The NRC is notifying you of this potential deficiency and the initial NRC actions to determine if NUMARC is interested in being the focal point for industry in resolving this issue.
Inifially, NUMARC may be able to assist industry by:
(1) coordinating the collection of information that identifies where bonded-jacket cables are used in nuclear plants and their installed l
i environmental conditions and (2) developing and coordinating a licensee inspection effort to determine the material condition of installed bonded-jacket cables.
l As you are probably aware, much of the Sandia test data that are the basis for
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the IN and the NRC concerns have not yet been published. Therefore, if NUMARC decides to assist industry in the resolution of this issue, we will notice a l
public meeting at Sandia with NUMARC as the industry focal point.
The meeting i
would be held at Sandia so that the test f acilities can be observed, test 290002 6l3
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Mr. William Rasin December 22, 1992 samples and test data can be inspected, and direct discussions can be held with the people who conducted the testing. By providing this opportunity to review the test data first hand, NUMARC and industry will be able to obtain an understanding of the Sandia test activities and the significance of the test results in order to better develop and coordinate an industry program to address the NRC's concerns with bonded-jacket cables.
If NUMARC is interested in assisting industry in the resolution of this issue, we would be happy to meet with you or members of your staff at your earliest convenience to discuss how NUMARC can best help industry and to provide more j
details on the staff's concerns relative to this matter.
If you have any questions regarding this letter or need further information on i
this issue, contact Conrad McCracken at (301) 504-28'1 or George Hubbard at (301) 504-2870.
Sincerely, M'
William T. Russell, Associate Director for Inspection and Technical Assessment Office of Nuclear Reactor Regulation
Enclosure:
As stated
. Enclosure-
- i UNITED STATES NUCLEAR REGULATORY COMMISSION 0FFICE OF NUCLEAR REACTOR REGULATION WASHINGTON, D.C.
20555 l
1 December 11, 1992 i
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NRC INFORMATION NOTICE 92-81: POTENTIAL DEFICIENCY OF ELECTRICA BONDED HYPALON JACKETS Addressees All holders of operating licenses or construction permits for nuclear power reactors.
I Purcose The U.S. Nuclear Regulatory Commission (NRC) is issuing.this information notice to alert addressees to a potential deficiency in the environmental It is qualification of electrical cables with bonded Hypalon ' jackets.
expected that recipients will review the information for applicability to their facilities and consider actions, as appropriate. However, suggestions contained in this information notice are not NRC. requirements; therefore, no specific action or written response to this notice is required.
Descriotion of Circumstances l
Sandia National Laboratories (SNL), under contract to NRC, has been conducting tests on cables manufactured by three different manufacturers, including The tests were performed to determine the minimum insulation Okonite.
thickness necessary for installed cable to perform its intended function should the insulation be damaged during installation, maintenance, or other Therefore, the thermal and radiation aging and. loss-of-coolant-activities.
accident (LOCA) testing for the cables were performed with reduced and full insulation thicknesses. The Okonite specimens tested were single-conductor, 500-volt,12 American Wire Gauge (AWG) control cables insulated with ethylene During propylene rubber (EPR) with a bonded Hypalon jacket (0konite-0kolon).
The other LOCA testing, all 10 of the Okonite-0kolon cable samples failed.
cables in this test program did not have bonded jackets and did not experience unexpected failures.
During this test program, the cables were first subjected to 130 megarads of radiation at the rate of 300 kilorads per hour for.433 hours0.00501 days <br />0.12 hours <br />7.159392e-4 weeks <br />1.647565e-4 months <br /> and were then Based on the Arrhenius-thermally aged at 158 *C (316 *F) for 336 hours0.00389 days <br />0.0933 hours <br />5.555556e-4 weeks <br />1.27848e-4 months <br />.
equation, accelerated thermal aging at this time and temperature is equivalent to a 40-year cable life at 69 *C (156 *F) for the jacket and 76 *C (169 'F) for the insulation. After thermal' aging, through-wall cracks were noted on most of the Okonite-0kolon cables. However, the cracks did not prevent the
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IN 92-81 December 11, 1992 Page 2 of 3 cables from passing an insulation resistance (IR) test that was conducted in a dry environment.
i The After the aging and IR tests, the cables were subjected to a LOCA test.
test sequence was (1) 94 hours0.00109 days <br />0.0261 hours <br />1.554233e-4 weeks <br />3.5767e-5 months <br /> of testing to simulate the LOCA environment defined in Appendix A to Institute of Electrical and Electronics Nuclear Power Generating Stations," and (2) 146 hours0.00169 days <br />0.0406 hours <br />2.414021e-4 weeks <br />5.5553e-5 months <br /> at 121 *C (250 *F) for (IEEE) Standard No chemical spray was used. The cables were One cable with the remainder of the test.
energized by 110-volt DC power during the test with no load By the fifth day of the test, all saturated at 11-1/2 hours into the test.
The test the Okonite cables had failed, as indicated by blown 1-ampere fuses.and the 24, 1992, chamber was opened on OctoberThe insulation and jacket on the Okonite cables had sp inspected.
length of the cable, and bare conductor was visible.
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the NRC staff visited SNL to evaluate the test failures, During that visit, SNL personnel informed the staff that other Okonite cables On October 28, 1992, with bonded Hypalon jackets had failed similarly at SNL under another_ NRC-For this test, the sponsored test program (license renewal test program). cables w l
One out of four Okonite-0kolon cables failed during LOCA testing.
Another group of Okonite cables that had been aged to a 40-year life at 50 *C (133 'F).
(122 *F) passed this testing.
I In addition to the Okonite failures in the license renewal test program, These cables manufactured by Samuel Moore also f ailed during LOCA testing.
cables were Dekoron Dekorad Type 1952, two-conductor, twisted, shielded pair, 16 AWG instrument cables covered with ethylene-propylene diene monomer (a type of EPR) insulation with a bonded Hypalon jacket and an ove 20-year life at 55 *C (131 'F), while the other cable in which both conductors Hypalon.
These f ailed had been thermally aged to a 40-year life at 56 *C (133 "F).
f ailures were similar to the failure of the Okonite-0kolon cable in th]
Other samples of Samuel Moore insulation and bonded jacket had split open.
cable survived aging and accident testing under similar conditions.
Discussion The SNL test results from NRC-sponsored programs raise questions with respect to the environmental qualification of Okonite cables with bonded Hypalon jackets that have not been specifically qualified for service conditionsThe exceeding 50 *C (122 *F) for 40 years.
data developed by the Okonite Company and noted that Okonite 2 kV cables w 0.76 mm (30 mil] bonded Hypalon jackets and 600-volt cables with un EPR insulation were previously tested.
mil] bonded Hypalon jackets were qualified based on the previous 2 kV a It was believed that if the unjacketed EPR insulation passed qualification testing, then EPR insulation with a bonded jacket w voit test results.
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IN 92-81 December 11, 1992 Page 3 of 3 However, the Sandia test results indicate also pass qualification testing.
that Okonite cable with bonded Hypalon jackets may be susceptible to failure.
The qualification data reviewed by the staff for the Samuel Moore cables showed that cables with bonded Hypalon jackets had been previously tested by The tests documented qualification of the Dekoron Dekorad Isomedix, Inc.
cable to a qualified life of 40 years at plant service conditions of 52 *C I
The test results from the license renewal test program at (126 *F) or less.
SNL raise questions about the qualification of Samuel Moore Dekoron Dekorad Type 1952 cables when used at higher temperatures.
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Other bonded-jacket cables, qualified for up to 90 *C (194 *F) applications as claimed by various vendors, may be susceptible to the same type of failures if The difference in aging not specifically tested in the bonded confirguration. rates between the ja Therefore, qualification testing that does not use the bonced-jacket cables.
jacketed configuration may not be representative of actual cable performance.
Depending on the ap;'; cation, failure of these cables could affect the The functional performance of safety functions in nuclear power plants.
integrity of the cables could be affected if the cables are used inside containment, used in continuous power circuits, routed with power cables, or Generic Letter 88-07, " Modified Enforcement Policy routed close to hot pipes.
Relating to 10 CFR 50.49, ' Environmental Qualification of Electrical Equipment Important to Safety for Nuclear Power Plants,'" provides relevant information on dealing with potential environmental qualification deficiencies.
If This information notice requires no specific action or written response.
you have any questions about the information in this notice, please contact one of the technical contacts listed below tr the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.
I
_.1 N rian K. Grimes, Director Division of Operating Reactor Support Office of Nuclear Reactor Regulation f
Technical contacts: Hukam C. Garg, NRR (301) 504-2929 l
Ann M. Dummer, NRR (301) 504-2831 1
List of Recently Issued NRC Information Notices
Attachment:
l l
i f
Attachment IN 92-81 December 11, 1992 Page 1 of 1 d
11 LIST OF RECENTLY ISSUED NRC INFORMATION NOTICES
-i Date or Information Issuance Issued to Notice No.
Subject l
92-80 Results of Thermo-Lag 12/07/92 All holders of OLs or cps for nuclear power reactors.
330-1 Combustibility Testing 12/01/92 All holders of Ols or cps 92-79 Non-Power Reactor for test and research Emergency Event Response reactors.
92-78 Piston to Cylinder 11/30/92 All holders of Ols or cps for nuclear power reactors.
Liner Tin Smearing on Cooper-Bessemer KSV Diesel Engines 92-77 Questionable Selection 11/17/92 All holders of Ols or cps I
for nuclear power reactors.
J and Review to Deter-mine Suitability of Electropneumatic Relays for Certain Applications 92-76 Issuance of Supple-11/13/92 All holders of OLs or cps for nuclear power reactors.
ment I to NUREG-1358, t
" Lessons Learned from the Special Inspection Program for Emergency Operating Procedures (Conducted October 1988 -
September 1991)"
92-75 Unplanned Intakes of 11/12/92 All holders of OLs or cps for nuclear power reactors.
Airborne Radioactive Material by Individuals at Nuclear Power Plants 92-74 Power Oscillations at 11/10/92 All holders of OLs or cps for nuclear power reactors.
Washington Nuclear Power Unit 2 92-61, Loss of High Head 11/06/92 All holders of OLs or cps for nuclear power reactors.
Supp. I Safety Injection OL = Operating' icense CP - Construction Permit
1 Mr. William Rasin environmental conditions and (2) developing and coordinating a licensee inspection effort to determine the material condition of installed bonded-jacket cables.
As more information on this issue becomes available and is evaluated, additional areas of concern may be identified.
If the information collected from licensees verifies that a deficiency exists in the qualification of bonded-jacket cable, additional generic communications may be appropriate.
In the event that a deficiency exists, NUMARC could further assist industry by coordinating the development and implementation of a long-term industry program to resolve the issue.
As you are probably aware, much of the Sandia test data that are the basis for the IN and the NRC concerns have not yet been published. Therefore, if NUMARC decides to assist industry in the resolution of this issue, we will notice a public meeting at Sandia with NUMARC as the industry focal point. The meeting would be held at Sandia so that the test facilities can be observed, test samples and test data can be inspected, and direct discussions can be held with the people who conducted the testing.
By providing this opportunity to review the test data first hand, NUMARC and industry will be able to obtain an understanding of the Sandia test activities and the significance of the test results in order to better develop and coordinate an industry program to address the NRC's concerns with bonded-jacket cables.
If NUMARC is interested in assisting industry in the resolution of this issue, we would be happy to meet with you or members of your staff at your earliest convenience to discuss how NUMARC can best help industry and to provide more details on the staff's concerns relative to this matter.
If you have any questions regarding this letter or need further information on this issue, contact Conrad McCracken at (301) 504-2873 or Cearge Hubbard at (301) 504-2870.
Sincerely, William T. Russell, Associate Director for Inspection and Technical Assessment Office of Nuclear Reactor Regulation
Enclosure:
As stated Distribution: See next page
- see previ,ous concurrence SPLB:DSSAjf@Q SPLB:DSSA Tech Ed.
SPLB:DSSA
- ADummer;cf
- GHubbard
- MMejac
- CMcCracken 12/7/9 12/
2 12/7/92 12/8/92 DRp9SSA
- tSSA AD:NRR GWolahan AThadani WTRussell 2 $ /92 12/%,/92 12/ /92
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t Mr. William Rasin able to obtain an understanding of the Sandia test activities and the significance of the test results to better coordinate the program.
If NUMARC is interested in assisting in the resolution of this issue, we would be happy to meet with you or members of your staff at your earliest convenience to discuss the scope and depth of NUMARC's involvement and to provide more details on the staff's concerns relative to this matter.
If you have any questions regarding this request or need further information on this issue, contact Conrad McCracken at (301) 504-2873 or George Hubbard at (301) 504-2870.
William T. Russell Associate Director for Inspection and Technical Assessment Office of Nuclear Reactor Regulation Enclosure As stated DISTRIBUTION:
Central File SPLB File TMurley JSniezek WBateman FMiraglia WRussell AThadani GHolahan CMcCracken GHubbard ADummer fDL 92.
SPLB:DSSA SPLB:DSSA Tech Ed.
B:DSSA ADummer;cf
- GHubbard
- MMejac CMcCracken 12/ /92 12/ /92 12/ /92 12/[/92 DD:DSSA D:DSSA AD:NRR GHolahan AThadani WTRussell 12/ /92 12/ /92 12/ /92
- see previous concurrence
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Mr. William Rasin.
able to have an understanding of the Sandia test activities and the significance of the test results to better coordinate the program.
If NUMARC is interested in assisting in the resolution of this issue we would
[
be willing to meet with you or members of your staff at your earliest convenience to discuss the scope and depth of NUMARC's involvement and to provide more details on the staff's concerns relative to this matter.
If you have any questions regarding this request or need further information on this issue contact Conrad McCracken at (301) 504-2873 or George Hubbard at (301) 504-2870.
P William T. Russell Associate Director for Inspection and Technical Assessment Office of Nuclear Reactor Regulation
Enclosure:
As stated DISTRIBUTION:
Central File SPLB File TMurley JSniezek WBateman FMiraglia WRussell AThadani GHolahan CMcCracken GHubbard ADummer SPLB:DSSA SPLB5 A
Tech Ed.
SPLB:DSSA JMain-p:.d g ;g-c, CMcCracken ADummer;cf[dI)
GHubbard 12/7/92 12/'7 /92 12/ 7 /92 12/ /92 j
DD:DSSA D:DSSA AD:NRR GHolahan AThadani WTRussell 12/ /92 12/ /92 12/ /92
[G:0KRASIN.AMD]
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