ML19351F255

Forwards Addl Info on IE Bulletin 79-01B Re Environ Qualification of Class IE Equipment,In Response to 801113 Telcon.Info Details Splice Integrity Where RTV 3145 Used for Splice Environ Barrier

ML19351F255
Person / Time
Site:	Fort Calhoun
Issue date:	11/19/1980
From:	William Jones OMAHA PUBLIC POWER DISTRICT
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
IEB-79-01B, IEB-79-1B, NUDOCS 8101120072
Download: ML19351F255 (4)

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o Omaha Public Power District STATE 1623 MARNEY OMANA. NESRASMA 68102 TELEPHONE S36 4000 AREA CODE 402 November 19, 1980 Mr. K. V. Seyfrit, Director U. S. Nuclear Regulatory Comission Office of Inspection and Enforcement Region IV 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011

Reference:

Docket No. 50-285

Dear Mr. Seyfrit:

In response to a discussion by telephone on November 13, 1980, between Messrs. Patterson and Mehaffey of Omaha Public Power Dis-trict and Mr. Mcdonald of your staff, additional information in response to IE Bulletin 79-01B is attached.

The attached inform-ation details the District's evaluation of splice integrity where RTV 3145 has been used for the splice's environmental barrier.

Sincerely,

'.N ti:w..,

W. C. Jones Division Manager Production Operations WCJ/KJM/TLP:jmm Attachment cc:

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

Washington, D.C.

20036 81011P00 Q

LOCA/MSLB ELECTRIC SPLICE PROTECTION BY 00W CORNING 3145 CLEAR RTY ANALYSIS As discussed in Licensee Event Reports 80-06 and 80-07, and in a of the District's letter dated October 31, 1980, in response to IE Bulletin 79-01B, the District is using RTV 3145 clear to insure the electrical splice integrity during harsh environmental conditions.

In the splice configurations, as discussed, the substrates provide the electrical characteristics of the splice, and RTV is used to provide an environmental barrier to prevent splice degradation.

If undisturbed by stresses, the RTV with substrate provides adequate splice integrity.

However, stresses imposed on the RTV by movement of the cable or steam /

water impingement could degrade splice operability.

Therefore, the District has conducted additional evaluation of these concerns.

i Based on the above splicir.g methodology, several additional factors were evaluated to insure splice operability.

The effects of operating stresses on the splice were reviewed.

Since the splice is mechanically passive, no mechanical change of position or configuration is expected during an accident. The presence of any additional protection was also considered. The containment vent fan motor splices are contained within the motor connection head junction box, and the transmitter splices are contained within a conduit fitting.

At the request of the District, Dow Corning performed a subjective compatibility tc, provide some additional data to insure splice integrity.

In this test, the adhesion of the RTV was rated.

The strongest and best type of adhesion is cohesive failure and is defined as adhesion having an adhesive bond stronger than either the adhesive material or the substrate. Adhesive failure occurs when the adhesive bond is weaker than the adhesive material and the substrate.

There are several grades of adhesive failure:

Poor - when little mechanical effort is required to separate the adhesive from the sub-strate. Good - when some mechanical effort is required to separate the adhesive from the substrate.

Excellent - when considerable mechnical effort is required to separate the adhesive from the substrate.

A copy of the results are attached.

The as-installed RTV at Fort Calhoun is the " solvent cleaned" as listed in the attachment.

The outer layers of the splice system are as follows:

Containment Vent Fan Motor Lead - Items 1, 8 Containment Penetra?. ion Vent Fan Splices - Items 4, 7 (In Con-tainment)

Containment Penetration Fan Splice - Items 3, 7 (_In Room 81)

Transmitter Splices - Items 6, 7, 9

2 In discussing the results and the splice configurations, the con-clusion was reached by Dow Corning and Omaha Public Power District that the splices should withstand these installed environments.

This con-clusion is based upon consideration that the.only splices open to a high stress environment are the containment penetration vent fan splices in containment (types 4 and 7).

The fan splices in Room 81 are subject to a much smaller stress than a LOCA and should be adequately protected.

All other splices are protected, as discussed above, or are outside containment. The types 4 and 7 substrates with RTV are the most re-sistant to stress failures.

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TABLE I Adhesion Of Dow Corning 3145 Silicone RTV To Various Cable Splicing Materials ADHESI0N Solvent Solvent Cleaned Substrate As Received Cleaned and Primed 1 Scotch 27 Tape A - Poor A - Poor A - Excellent 2 Scotch 70 Silicone Tape C

C C

3 Scotch 88 Tape A - Poor A - Poor A - Excellent 4

G.E. Irrasil Silicone Tape C

C C

5 AMP L-79F Heat Shrink Tubing A - Poor A - Poor A - Poor 6 AMP Clear Plastic Tubing A - Poor A - Poor A - Poor 7 Rockestos Pyrotrol Cable (Neoprene)

A - Poor A - Poor C

8 Crosslinker Polyethylene Wire Jacket A - Poor A - Poor A - Good 9 Foxboro Transmitter Lead Wire A - Poor A - Poor A - Good C = Cohesive Failure (see earlier discussion)

A = Adhesive Failure (see earlier discussion)