ML20040B214

Forwards Revisions to Encls to Util 820826 Ltr Re Environ Qualification of safety-related Electrical Equipment. Revisions Consist of Changes to Encl 8 Re Cable Splice Evaluation & Encl 16 Re Main Steam Line Break Analysis

ML20040B214
Person / Time
Site:	Fort Calhoun
Issue date:	01/14/1982
From:	William Jones OMAHA PUBLIC POWER DISTRICT
To:	Clark R Office of Nuclear Reactor Regulation
References
LIC-82-019, LIC-82-19, NUDOCS 8201250274
Download: ML20040B214 (6)

Text

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.1 Omaha Public Power District 1623 HARNEY a OMAHA. NEBRASKA 68102 m TELEPHONE 536 4000 AREA CODE 402 January 14, 1982

• e g LIC-82-019 \

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Mr. Robert A. Clark, Chief 9: JAN 2 219825 G1 U. S. Nuclear Regulatory Commission Mica tenn.ra ,

Office of Nuclear Reactor Regulation y D juy m e p ,

Division of Licensing

Operating Reactors Branch No. 3 q, ,

Washington, D.C. 20555 N

Reference:

Docket No. 50-285

Subject:

Environmental Qualification of Safety-  :

Related Electrical Equipment  !

! The Omaha Public Power District's letter dated August 26, 1981 provided  !

the most recent, co,nplete submittal regarding the Fort Calhoun Station's  !

environmental qualification of safety-related electrical equipment in a i harsh environment. This letter transmits revisions to Enclosure 8,

" Cable Splice Evaluation," and Enclosure 16, " Main Steam Line Break Analysis," of Attachment 2 to the subject letter. These revisions [

reflect the receipt of further clarification information ard do not  !

change the conclusions as presented in the District's August 26, 1981  :

letter. [

l Attached to Enclosure 8 of the August 26, 1981 letter was a preliminary i i assessment report that provides the results of environmental qualifi- l l cation tests on the Fort Calhoun Station's electrical penetration cable [

splices. To conduct this preliminary analysis, five assumptions regard-ing cable splice design and construction were necessary because in- i containment verification was impossible during power operation. The i five assumptions are listed in Section 4.0 of the preliminary assessment i report. The District stated in-containment verification of the as-  !

sumptions was necessary and, during the recent 1981 refueling outage,  !

District personnel visually inspected the appropriate splices and con- f l firmed their validity. Since these assumptions are valid, the Franklin  !

Institute Report F-C-3348 (April 1972), which demonstrated environmental  :

qualification of similar cable splices, is applicable and encompasses l the Fort Calhoun Station electrical cable splices. A revised Enclosure  ;

8 discussion page, which includes this new information, is attached. A L final report on the environmental qualification of these cable splices l will be provided when the District's contractor completes additional i analyses. The District expects to provide the Commission with this  ;

report by June 30, 1982. t 8201250274 820114 r PDR ADOCK 05000285 5:

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Mr. Robert A. Clark LIC-82-019 Page Two Enclosure 16, " Main Steam Line Break Analysis," has been updated to revise the calculated peak temperature inside of containment during a main steam line break (MSLB) to 3550F, compared to the previous value of 4010F. The lower calculated peak temperature is the result of taking credit for containment spray in the MSLB analysis, which further reduces containment peak temperature. The District has also updated the minimum temperature profile for equipment qualification during a large break loss of coolant accident (LBLOCA) to the recongnended 3050F, from the previous 2880F. As a result, containment temperature during a MSLB exceeds the LBLOCA profile by 500F for a period of approximately thirty seconds, compared to the previous result of 1150F for two minutes. A revised Enclosure 16 (pages 16-1 through 16-3) is attached which in-corporates this new information. Enclosure 16 demonstrates the MSLB peak temperature of 3550F does not degrade the performance of safety-related electrical equipment in containment. Therefore, the presently installed electrical equipment is adequate and will perform its intended function following a MSLB.

Sincerely, b

W.C. jones Divis on Manager Production Operations 4

WCJ/KJM/Tl P/RWS:jnun Attachments cc: LeBoeuf, Lamb, Leiby & MacRae 1333 New Hampshire Avenue, N.W.

Washington, D.C. 20036 i

l l

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Enclosure 8 Cable Splice Evaluation In its November 1,1980 subnittal regarding IE Bulletin 79-01B, the District committed to providing beta radiation data for cable splices.

Attached is the Wyle Laboratories Preliminary Assessment Report on Cable Splices Inside Containment for Fort Calhoun Station Unit No.1.

The report provides a comprehensive preliminary summary of all harsh environmental parameters, including beta radiation effects.

The report is considered preliminary because a qualified life / radiation study is still being conducted to determine overall qualification.

The five assumptions included in the preliminary report have been confirmed by visual inspection of the in-containment cable splices during the 1981 refueling outage. The results of the inspection indi-cate the Fort Calhoun Station's safety-related electrical cable splices  !

conform to Franklin Institute Report F-C-3348, dated April 1972, which demonstrated environmental qualification for similar splices.

Based on infonnation in the report, the District feels that continued safe operaticn is justified. A final report will be issued after a qualified life / radiation study has been completed by the District's contractor.

8-1 R2 1/6/82

Enclosure 16 Main Steam Line Break (MSLB) Analysis The qualification criteria assumed to date includes a maximum temp-erature of 3050F based on conditions in containment due to Large Break LOCA. In response to the Containment Spray Header Work (Seismic Brac-ing), the District recently performed a MSLB analysis to confirm that the containme't pressure limit was not exceeded due to the addition of feedwater by the " control grade" (which bounds the safety grade) auxi-liary feedwater actuation system. A portion of the results of this analysis for the temperature transients are given on the attached figure (Figure 1) which shows a peak temperature of 3550F. These results show l the containment temperature exceeding the assumed qualification limit of i 3050F during the period of 25 seconds to 60 seconds following a MSLB. '

To insure the MSLB does not degrade electrical equipment performance, the District compiled a list of outer materials which could be exposed to temperature, then performed analyses to evaluate material heating as a resul t of the temperature transient.

The results of the analyses of each " type" of electrical equipment i installed is given below:

1. Limitorque valve operators are qualified to 3290F for 40 minutes. During the 30 seconds containment temperature is above 3290F, the outer steel cover should prevent heating which will damage the M0V's.

2. Rockbestos Cable is qualified by testing at 3400F for 500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br />. The non-metallic neoprule jacket is a poor heat conductor and it is probable the inner insulation would never be exposed for the short period of time above 3400F for the MSLB, no damage is likely to occur.

3. Penetration Splices - Similar to the cable splices, Pentube, tested 4820F for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> per catalog data. Therefore, the MSLB temperature transient does not impact splice integrity.

4. Transmitter Solenoid Valve Splices are protected by conduit fittings similar to penetration splices.

5. Containment Vent Fan Motor and Penetration Splices are non-metallic and covered with RTV 3145 which is tested at 3920F for 100,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />.

6. Conax Penetrations are of steel and teflon construction, tested at 3050F for 20 minutes. The Standard Handbook of Electrical Engineers shows a maximum service temperature of 5500F for Teflon. No problems should be encountered for the MSLC.

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l 16-1 R3 11/23/81

7. ASCO NPl type solenoids are tested 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> at 3400F. Con-versations with the manufacturers indicate no problem should be encountered for the short time exposure above 3400F.

8. Foxboro Transmitters - Steel Covers Test Report T4-6061 of transmitters similar to Fort Calhoun, indicates no internal heating would occur that could impair the transmitter func-tion. It should be noted that the older transmitters have aluminum covers and it is felt that the transient would not cause excessive internal heating. After the metal core had heated to approximately 3240F it required some 8 minutes for the output transistor to reach 1950F. This is well below the 3180F test temperature and even with 3550F input the short time duration will preclude any damage.

9. Valcor Solenoids are tested at 3460F for 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. It is not expected that the 26 second temperature transient will effect the solenoid's operation.

10. Raychem Breakout Kits are tested at 38E O F for 4 minutes. This test should insure the operability of the breakout kit on the Valcor Solenoid Valves.

11. Joy Manufacturing Containment Vent Fans are tested to 4000F.

This test, in addition to the heavy outer case, will insure motor operability.

12. The Terminal Blocks (States) were tested at 3400F for 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />.

This test plus the fact that the blocks are mounted in a metal junction box, covered with RTV, and that they are a passive device will insure operability in a MSLB transient.

13. NAMC0 Limit Switches are tested at 3400F for 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. The limit switches are for indication only. The temperature transient should not effect the internal operation, and will l not affect plant safety even with failure.

14. Allison Controls - Charcoal Filter Temperature. The device is built for ranges of greater than 10000F. The interface with the cable is similar to the terminal block description.

The MSLB pressure analysis was performed to verify the containment design pressure was not exceeded and contained a number of conservative assumptions. These included limited credit for known heat sinks within containment and failure of gravity operated main steam line reverse flow check valves. Credit for either or both of these would result in a less severe environment. The District has concluded the presently installed equipment is adequate for the MSLB environment. This conclusion is based upon the short duration (35 seconds) that the MSLB temperature exceeds the LOCA peak temperature, the heat transfer characteristics of protective coatings on safety-related electrical equipment, and the additional conservatism in the MSLB analysis. In addition, the Fort Calhoun Station is equipped with a containment spray system which meets single failure criteria.

16-2 R3 11/23/81

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FIGURE *.I FORT,CALHOUN CONTAINMENT MAIN STEAM LINE DJ BREAK TEMPERATURE (*F) VERSUS TIME AFTER g_

BREAK (SEC) FOR WORST CASE ENERGY RELEASE. m REF* MICROFICHE A05YEPK DATED 6 81 A

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@ 200 g

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, C0_NTAIN ME NT_SPR AY 10 0  !'

O 20 40 60 80 10 0 I20 TIME AFTER BREAK (SEC)

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