ML20035H052
| ML20035H052 | |
| Person / Time | |
|---|---|
| Issue date: | 01/27/1993 |
| From: | Thadani A Office of Nuclear Reactor Regulation |
| To: | Roe J, Travers W, Varga S Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20034D513 | List: |
| References | |
| GL-88-07, GL-88-7, IEIN-92-081, IEIN-92-81, NUDOCS 9305030038 | |
| Download: ML20035H052 (3) | |
Text
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January 27, 1993 MEMORANDUM FOR:
Steven A. Varga, Director Division of Reactor Projects I/II, NRR Jack W. Roe, Director Division of Reactor Projects III/lV/V, NRR William D. Travers, Deputy Associate Director for Advanced Reactors and License Renewal, NRR FROM:
Ashok C. Thadani, Director Division of Systems Safety and Analysis, NRR STAFF ACTIONS FOR THE RESOLUTION OF A POTENTIAL DEFICIENC
SUBJECT:
IN THE ENVIRONMENTAL QUALIFICATION OF BONDED-JACKET CABL The purpose of this memorandum is to inform you of recent developments As regarding failures of Okonite and other bonded-jacket electrical cables.
discussed in recent Director's Highlights, cable failures during testing conducted by Sandia National Laboratories have identified a potential deficiency in that bonded-jacket cables have a potential for failure during a LOCA before 40 years, if these cables are used at temperatures greater than 50 "C (122 "F).
Based on the results of the Sandia testing and reviews of environmental
" Potential qualification test reports, Information Notice (IN) 92-81:
Deficiency of Electrical Cables with Bonded Hypalon Jackets" (Enclosure 1) was issued on December 11, 1992, to inform licensees of the staff's concerns related to the use of bonded-jacket cables at temperatures greater th.n 50 "C Additionally a memorandum, subject, " Failures of Okonite Electrical (122 "F).
Cables with Bonded Hypalon Jacket During Tests Performed by Sandia National 10, 1992 (Enclosure 2), was sent to the Laboratories," dated December This memorandum discussed safety concerns and planned actions Commission.
regarding this issue.
The Plant Systems Branch has been assigned the lead for this issue and has It should-be developed a preliminary task action plan outline (Enclosure 3).
noted that the dates and activities are subject to change as information is obtained and a detailed action plan is developed.
While the staff has determined that there is no immediate safety concern, the staff is evaluating the long term safety significance of this potential In its evaluation, the staff will include any information deficiency.
obtained from the licensees which may have been developed in response to In particular, this information may be developed when licensees IN 92-81.
take any necessary actions described in Generic Letter 88-07, " Modified Enforcement Policy Relating to 10 CFR 50.49, " Environmental Qualification of
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9305030038 930127 PDR REVGP ERGNUMRC PDR
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. January 27, 1993 Directors Electrical Equipment Important to Safety for Nuclear Power Plants,'" if the licensees determine they have the potential deficiency described in the IN.
As part of this evaluation and in accordance with the letter to the Commission, a letter identifying the concerns has been sent to NUMARC In addition, the letter reeks to determine if NUMARC is (Enclosure 4).
interested in assisting industry in resolving the concerns identified in the Suggested areas where NUMARC could assist industry were (1) coordinating IN.
the collection of information that identifies where bonded-jacket cables are used in nuclear plants and their installed environmental conditions and (2) developing and coordinating a licensee inspection effort to determine the
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NUMARC has not yet material condition of installed bonoed-jacket cables.
responded to the staff's letter.
While the staff plans to work with NUMARC as the industry focal point on this issue. we are also taking steps to issue a Generic Letter, if it is needed, as a method to obtain information to ascertain the long term safety I
In order to provide background information for significance of this issue.
the Generic Letter, assistance from NRR Projects and Regions may be requested.
If assistance is required, Projects and/or Regions will be contacted as appropriate.
504-2870.
If there are questions about this issue, contact George Hubbard at L
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,/gktAshokC..Thadani, Director Division of Systems Safety and Analysis Office of Nuclear Reactor Regulation t
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Enclosures:
As stated cc w/ enclosures:
W. Russell J. Partlow
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NUCLEAR REGULATORY COMMISSICN FFICE OF NUCLEAR REACTOR REGULATION WASHINGTON, D.C.
20555 Decemoer 11, 1992 POTENTIAL DEFICIENCY OF ELECTRIC NRC :NFGRMATION NOTICE 92-81:
BONDED HYPALON JACKETS Addressees l
all holders of coerating licenses or construction permits for nu reactors.
Ourcose NRC) 1s issuing this information in the environmental 1e U.S. Nuclear Regulatory Commission (
notice to alert accressees to a cotential ceficiency i
jackets.
It is
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cualification of electrical caoles with bonced Hypa onfor applicability to exoecteo that rectoients will review the information However, suggestions i te.
tneir facilities ano consider actions, as appropr ai ents; therefore, no contained in this information notice are not NRC requ rem quired.
specific action or written response to this notice is re Descriction of Circumstances has been conducting Sancia National Lacoratories (SNL), under centract to NRC,ufac tests en cables manufactured by three different manThe t l
i thickness necessary for installed cable to per o aintenance, or other Okonite.
- nould ne insulation ce camageo during installation, mT f
lant-acc1 cent (LOCA) testing for the caoles were performeo wThe activities.
h ethylene 12 American Wire Gauge (AWG) control caoles insulat insulation thicknesses.
ite-0kolon). During rooyiene rueber (EPR) with a bonoed Hypalon jacket (Okon l s failed. The other 500-volt, LOCA testing, all 10 of the Okonite-0kolon cable samp e d did not experience caoles in this test orogram did not have bonded jackets an unexpecteo failures.
to 130 megarads of Ouring this test ;rogram, the cables were first subjectedfor 433
-aoiation at the rate of 300 kilorads per hour Based on the Arrhenius d temperature is eouivalent thermally ageo at 153 *C (315 *F) for 336 hours0.00389 days <br />0.0933 hours <br />5.555556e-4 weeks <br />1.27848e-4 months <br />.
ecuation, accelerateo thermal aging at this time annd 76 *C (169 *F) 4 o a 40-year caole life at 69 *C (155 *F) for the Jacket a t a on tfter thermal aging, througn-wail cracks we for the insulati:n.
most cf the Okonite-Gkolon caoles.
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IN 92-81 Decemoer 11, ;992 Page 2 of 3 l
in a
- acles from passing an insuiation resistance (IR) test that was conouctea ory environment.
The i
'fter the aging and IR tests, the cables were subjected to a LC.A test.
A environmerit test secuence 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 LOC l
- efinea in Appendix A to Institute of Electrical and Electro (IEEE) Standard
" ana (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 Nuclear Power Generating Stations,No enemical spray was used.
One cable with The cables were the remainder of the test.
energizea by 110-volt DC power curing the test with no lo l
By the fifth day of the test, all saturated at 11-1/2 hours into the test.
The test he Okontte cables had failed, as indicated by blown 1-ampere fuses.an 24, 1992, cnaccer was opened on OctocerThe insulation and jacket on the Okonite cables nad insoected.
'.engtn of the cable. ano bare conouctor was visible.
the NRC staff visitea SNL to evaluate the test failures.
- uring that visit SNL personnel informea the staff that other Okontte caole On Ccteoer 28, 1992, h
NRC-with conced Hypalon jackets hao f ailed similarly at SNL under anot erFor this test, the
- cnsorea test program (license renewal test program).
caoles were thermally agea to the ecu1 valent of a 40-year life at 56 *C One out of four Okonite-0kolon cables failed during LOCA testing.
Another group of Okonite caoles that nac been aged to a 40-year life at 5 (133 *F).
(122 'F) passed this testing.
In addition to the Okontte failures in the license renewal test program, These l
caoles manufactured by Samuel Moore also failed durin 1
ciene monomer (a type
- 5 AWG instrument caoles coverea with ethylene-prooyler<
- f EPR) insulation with a bonaed Hypalon Jacket ano 20-year life at 55 'C (131 'F),
nile the otner caole in wnicn both conductors "ypalon.
These
'alieo had been thermally ageo to a 40-year life at 55 Other samples of Samuel Moore nsuiation and banced jacket had split open.
caole survived aging and accident testing under similar concitions.
Discussion
~he SNL test results from NRC-sponsored programs raise questions with r l
to the environmental cualification of Okonite cables with benced Hypa on Jackets that have not teen specifically cualified for service conoitions 4
- ata cevelooed by the Okonite Comoany and noted that Okonite 2 kV exceecing 50 'C (122 'F) for 40 years.
0.75 mm [30 m11] bonced Hypalon jackets and 600-voit caoles with d 600-EPR insulation were previously testea.
mil) tonced Hypaion jackets were cualified based on the previous 2 kV It was believea tnat if the unjacketec EPR insulation
- assea cualification testing, then EPR insulation with a conced jac
.oit test results.
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IN 92-81 Decemoer 11, ;992 Page 3 of 3 9
However, the Sancia test results inoicatetible to failure also pass cualification testing.inat Okonite caDie with bonoed Hypalon l Moore cables
'he cualification data reviewed by the staff for the Samue viously tested by
- nowea that caoles with benced Hypalon jackets had bee ditions of 52 *:
- sole to a qualified life of 40 years at plant service conThe t
- someaix, Inc.
Dekoren Oekorad jNL raise questions about the qualification of Samuel Moore
- 126 'F) or less.
iype 1952 cables when used at higher temperatures.*F) applications as Other tonced-jacket cables, qualified for up to 90 type of failures if tion.
not specifically tested in the boncea confirgurabe a factor in the failure of rates between the jacket and the insulation mayTherefore. :aalification te l cable performance.
- acKetea configuration may not te representative of actua
- nceo-Jacket caoles.
ffect the
- ecenoing on the application. failure of these cables could a The functional
- erformance of safety functions in nuclear power sed inside d with power cables, or containment, used in continuous power circuits, routeGeneric Let Relating to 10 CFR 50.49, ' Environmental Qualifi routed close to hot pipes.
information deficiencies.
en dealing with potential environmental qualification sponse.
If
~his :nformation notice recuires no specific action or written re ice, please contact jou have any cuestions about the information in thi t Office of Nuciear Reactor Reguiation (NRR) project manager.
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erian K. Grimes, Director Division of Operating Reactor Support Office of Nuclear Reactor Regulation Hukam C. Garg, NRR Tecnnical contacts:
(301) 504-2929
- nn M. Cummer, NRR (301) 504-2831 List of Recently Issueo NRC Information Notices tt;cnment: