ML20027D617

Forwards Environ Qualification Evaluation of Cable Splices Inside Containment for OPPD for Use in Ft Calhoun Nuclear Generating Station,Unit 1. Cable Splices Will Operate as Required During & After Accident

ML20027D617
Person / Time
Site:	Fort Calhoun
Issue date:	11/01/1982
From:	William Jones OMAHA PUBLIC POWER DISTRICT
To:	Clark R Office of Nuclear Reactor Regulation
Shared Package
ML20027D618	List: ML20027D617 ML20027D627
References
LIC-82-299, NUDOCS 8211080164
Download: ML20027D617 (8)

Text

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Ornaha Public Power District

" OMAHA, NEBRASKA 68102 ' TELEPHONE S36-4000 AREA CODE 402 1623 HARNEY November 1, 1982 LIC-82-299 Mr. Robert A. Clark, Chief U. S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Division of Licensing Operating Reactors Branch No. 3 Washington, D.C. 20555

Reference:

Docket No. 50-285

Dear Mr. Clark:

l Environmental Qualification of Safety-Related Electrical Equipment at the Fort Calhoun Station Omaha Public Power District's letter to the Commission, dated May 18, 1982, identified three qualification reports that remained to be l provided to Franklin Research Center (FRC). These qualification reports are required to provide all information requested in the Commission's letter dated February 18, 1982. One of the three reports is the Wyle Laboratories final report for electrical cable splices located inside containment. The purpose of this letter is to inform the Commission that the subject qualification report has been received by the District and that a copy has been forwarded directly to FRC, as specified by the February 18, 1982 letter.

The Commission should note that the subject report concludes that, based upon an engineering and materials analysis evaluation, the Fort Calhoun Station cable splices will operate as required during and af ter postulated accident conditions. The report also states that insufficient accident test data exists to actually demonstrate this full qualifi-cation for several cable splices identified in Section 5.0, "Conclusins",

of the report. Item 11 of Attachment 1 to the District's letter dated September 9,1982 identified modifications and remaining testing that will be completed for the cable splices identified by Items 1(c),1(d),

2, and 3 in Section 5.0 of the report to eliminate this splice concern.

.p Q However, the District believes the containment vent fan motor lead wire 8211080164 821101 PDR ADOCK 05000285 P PDR

Mr. Robert A. C1drk .

LIC-82-299 Page Two e

and electrical penetration cable splices (Items 1(a) and 1(b) of Section 5.0) are fully environmentally qualified and no further action is planned. Justification.for this conclusion is provided in the attach-ment. A copy of the subject Wyle report is also enclosed for reference and use by the Connission.

Sincerely, l hi Jones W. C.j'on Manager Divisi Production Operations WCJ/TLP:jmm Attachments t

cc: LeBoeuf, Lamb, Leiby & MacRae 1333 New Hampshire Avenue, N.W.

- Washington, D.C. 20036 Mr. Cyril J. Crane Franklin Research Center The Parkway at Twentieth Street Philadelphia, Pennsylvania 19103 l

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. . Attachment ENVIRONMENTAL QtlALIFICATION OF THE CONTAINMENT VENTILATION FAN MOTOR (VA-3A, VA-3B, AND VA-70)

CABLE SPLICES LOCATED AT THE MOTOR LEADS AND ELECTRICAL PENETRATIONS Based on the results of the Wyle Laboratories evaluation of the Fort Calhoun Station cable splices and the District's engineering -

judgment, the 480 VAC vent fan motor cable splices at the motor leads and on ooth sides of the containment electrical penetration are ade-quately qualified for both LOCA and post-LOCA environments. The key to full qualification of these splices involves the consideration that the splice is a system in which the inner layers of tape ensure the electrical integrity of the circuit. The outer layer of RTV sealant (Dow Corning 3144 or 3145 clear) provides the protection and electrical insulation from normal and potential harsh environment parameters. A complete description of the motor lead cable splice system is detailed in En-closure 9 to the District's letter dated August 26,1981~ (a copy of this enclosure is attached for convenience). A description of the cable splice system at the electrical penetrations is provided as Figure 1, page 22 of the enclosed Wyle Laboratories report.

To substantiate the District's engineering judgment, each of the applicable environmental stress parameters (pressure, humidity, steam, temperature, chemical spray, radiation, and aging) were evaluated to determine their impact on the splice systems. The results of the investigation are as follows:

1. Pressure: The splices are a mechanically passive system which provide electrical insulation and protection for the con-nection. Insulation has been placed over the connector and wire jacket in such a fashion as to minimize voids and a layer of RTV covers all of this. With this configuration and the small surface area of the splice, only a small mechanical force can be exerted. The District believes this small compression could not cause mechanical damage that would lead l

to splice failure. In addition, this force tends to compress the splice, ensuring water tightness. Aging information indicates that the material should remain functional through-out the life of the plant, indicating that a pressure transient should not cause splice failure. This conclusion is also substantiated by the fact that the splices have remained i functional throughout three containment integrated leak rate l tests in which the fans operated at accident pressure.

2. Humidity: The RTV and various tapes provide an adequate barrier which is substantiated by almost 10 years of suc-cessful operation. (NOTE: The RTV was applied to the elec-trical penetration splices in 1980.)

3. Steam: The District believes the protection provided by the RTV is an adequate barrier to steam.

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4. Temperature: Wyle Laboratories Report No. 26333-26 concludes that the splices and their material constituents can withstand the effects of exposure to the peak accident temperature of 3050F. Plea:e refer to Section 4.3.3.3 of the subject report.

5. Chemical Spray: The only splices which potentially could be exposed to chemical spray are the containment side electrical penetration splices. The motor lead splices are protected by a junction box, and the penetration splices in Room 81 cannot be exposed to chemical spray. Nevertheless, RTV is not af-fected by mild basic solutions and should preclude damage by chemical spray.

6. Radiation: For radiation qualification, three categories of splices were evaluated and the results are presented below.

The first splice of concern is the electrical penetration cable splice located in Room 81 cf the auxiliary building.

These splices are outside the containment and are not expected to be affected by radiation. 'No further evaluation is re-quired for these splices.

The second splice category includes the vent fan motor lead wire splices inside containment. These splices are protected by a junction box which eliminates the effect of beta radi-ation on the splice. Calculations indicate that VA-3A and VA-3Bcouldbeexposedtoamaximumgammadoseof8.64xig6 rads, and VA-7C and VA-7D could be exposed to 1.92 x 10 rads gamma. Both of these exposures are less than the 1.0 x 108 rads _tnreshold level for these splices which is summarized in Table 5 of the Wyle report.e The third category of splice evaluated was the electrical penetration cable splices located inside containment. The radiation exposures to these splices would be as follows:

Maximum Exposure at Maximum Exposure at I.D. of RTV & 0.D. of 0.D. of RTV (Rads) , Splice Insulation (Rads)

Ganina Radi- 1.475 x 107 (1) 1.475 x 107 ation Beta Radi- 2.0 x 108 (2) 2.0 x 105 (3) ation l

Total Inte- 2.148 x 108 1.495 x 107 )

grated Dose  !

(TID)  !

NOTES:

(1) Includes a normal exposure of 3.5 x 105 rads (i.e., a conservative 1 R/hr for a 40 year operating life) and an accident exposure of 1.44 x 107 rads.

(2) Combined normal and accident exposure as recommended by the 00R guidelines.

(3) RTV of approximately 1/8" thickness (125 mils) reduces the beta radiation by a factor of 10 ducingthebetaexposureto2.0x10g0,thereforere-rads at the outer layer of splice tape.

As indicated in the table above and in the Wyle Laboratories report, the RTV is a nominal 1/8" thick on the splice and attentuates the beta exposure to approximately 2.0 x 105 rads at the splice RTV/ tape interface. This res the tape surrounding the splice of 1.5 x 10ylts in aInTID

. rads. re-to viewing the effect of this radiation exposure on the splice electrical insulation (i.e., tape), a system review is neces-sary. The insulation consists of inner layers of Irrathene SPT tape, and Irrasil and Scotch 33 tape are utilized for protection and to hold the Irrathene SPT tape. Item 3 of Table 3 on page 29 of Wyle Report No. 26333-26 demonstrates that the Scotch 33 and Irrathene SPT tape provide adequate radiation resistance to the maximum expected exposure. The Irrasil tape could be expected to degrade after approximately one hour of accident operation; however, since its purpose is to hold the qualified Irrathene SPT tape and is itself sup-ported by the Scotch 33 tape, the District believes the Irrasil tape would not contribute to failure of the splice system.

Additionally, in reviewing radiation test information (at-tached) provided by Dow Corning, both RTV 3144 and 3145 clear are known to embrittle with radiation exposurg. However, RTV 3144 did not fail at an exposure of 1.94 x 10 rads and failure only occurred after mechanical stress was applied at 4.55 x 108 rads. Based on this embrittling test information, and the fact that each 30-40 n.ils of RTV reduces the beta radiation by a factor of ten, the District is confident that at a minimum the inner thickress of RTV will maintain its integrity and ensure operability of the splice.

7. Aging: Wyle Laboratories Report No. 26333-26 indicates that ,

no aging related failures should be encountered. Please refer to Section 3.0 of the subject report'for details.

Conclusion The District believes these splices are fully protected and quali-fied based on the results of the testing completed for RTV and the fact that RTV protects the electrical insulation. Based on this analysis and the supporting documents, no further action is required.

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S ENCLOSURE 9

- Contain=ent Fin Cceler Meter Solices d%l The e--- '---~~ cooler fan =cter lead splices (7A-3A, 33, TC, and TD

=ctor lead splices) are, in OPPD's engineering judg=ent, envirer.=entally qualified for the adverse conditions of a LOCA. Reasons for this judsnent ete= fres the fcilev1ng: .

) 1) First, eignt half-laps of Sectch 3 rand #70 tape are applied to the bare joint / splice. Second, eight half-laps of Bishop 3 rand #3 high voltage tape are applied over the splice sur-face. Third, the joint / splice. area is then covered with eight half-laps of Sectch 3 rand i88 tape. Fourth, an additional two half-laps of Scotch 3 rand #70 tape ,is then applied over the general splice / joint area. Lastly, the entire splice /jcint area is covered with Dev Corning RTV #31kh ce= pound at least 1/8" thich er.d at least 1" beyond all applied tape. The RT7 is s=cothed to ec=pletely seal the splice / joint and then the

• RT7 is a11 cued to cure in acccrdance with instrue:1or.s.

2) Recent conversaticas with the =anufacturer of Sectch Brand #TO and #88 tapes have revealed satisfactory test results were ob-tained for sa=ples of' the two afore=entioned tapes when sub ,

jected to radiatica fields in the neighborhood of 50-100 x 100 rads.

Due to the RT7 sealant, this tape vill not be subjected to the pressure, toisture (1005 R.R. ), beric acid conditions present in a LOCA. In addition, both tapes centiened above are capable of cperating in te=peratures in excess of 3500F vith ne subse-

• Sh quent da= age. ,

3) The entire splice / joint is covered with a layer of RT7 #31hh adhesive / sealant. Conversations with the =anufacturer of the RTY, Dov Corning, revealed that several laboratory tests were run en the afore=entioned'RT7. Results of these tests revesled that the Dov Cerning RT7 #31hh ves capable of operating in en-viren=ents greater than 102 x 10 5 rads (total integrated dose) vith no appreciable deficiencies. In additica, the #31hh RTY reacts with water vapor in the air to cure. Upcn curing, the ,

adhesive / sealant beco=es resistant to hu=idity and temperatures up to k82cr over long perieds of ti=e. The RT7 #31hk sealant vill effectively seal off all enviren=ents fro = the underlying Scotch 3 rand tapes and the' splice except for radiation. The

1. 31kk RT7 is also not adversely affected by boric acid solutions in excess of 55.

Further evidence of Dow Corning #31hk RTV sealant / adhesive's ability to stand up to the adverse conditions of a LOCA is decu=ented by the Fisher Centrols Cc=pany valve actuator tests .

, In these tests, Dov Corning #31kk adhesive / sealant was used to cover all bare ter=inations. Results of the tests provided evidence that throughout the si=ulated LOCA environ =ent no ter=ination covered with #314h RT7 vas found to be shorted or dansged. Test para =eters included te=peratures in excess of 2SSCF, pressure in excess of 60 psig, and a 100% saturated y stea= envirencent.

No credit is taken for the 31 shop #3 high voltage tape.

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