ML20105C012

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Discusses Visconorust 2090 P-4 Casing Filler Inservice Tendon Surveillance.Key to Sys Is Fully Coating Tendon & Some Initial Penetration Into Tendon Bundle During Original Pumping
ML20105C012
Person / Time
Site: Vogtle Southern Nuclear icon.png
Issue date: 04/19/1990
From: Novak C
TENNECO, INC.
To: Ashar H
Office of Nuclear Reactor Regulation
Shared Package
ML20105C009 List:
References
NUDOCS 9209220012
Download: ML20105C012 (3)
v • d • e


Text

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FEB-17-1992 11:55 FRCM VCGTLE-TEi.rt41Cft. 959CRT' TO 9C OG4.1C= P.11

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April 19,1990

- Mr. Hans Ashar Ottice of Nuclear Reactor Regulation U.S. Regu! story Commission Mail Stop WF18022

- Washington, D.C. 20555

Subject:

Visconorust 2090 P-4 Casing Filler insarvice Tondon Survellianco

Dear Mr. Asbar:

We are wrning you those following comments on some inservice Tencon Survail'ance requirements that have recentl

- with the NRC for many years. y come to our attention as you have been our contact In September of 1985, a Mr. Andrevy P. Neuhalf6n, Union Electric Co., wrota a letter to Mr. James G. Ke aplar, Regiona! Admirds'ratcr, U.S. NRC, Glen Ellyn, IL. a copy of A

which is attachec, that we thought certainly addressed the rnatter of voids in the ducts in Survemance and the action of our corrosion preventive very well.

We weie never questioned on this matter, nor asked to visit any comrpittees that were revie,ving Tendon Survelllance after the original committee meetings years ago.

The point of our letter is that the statements comming from the NRC requiring that the void area in a tendon be less than 5% is an impossible situation, as also noted by the comments in Mr. Neuhalfen's letter.

The origina; design of our system took into account that there would be voids, and a total 20% void mado up of the different variab'ws could happen. This is one of the.

reasons each member of the tendor was coawd with our initial coatings - Visconorust 1001 Amber or both the Viscornrust 1601 Amber and 1702 to be sure i.no intema!

members of the tendon were coated until the Visconorust 2090 P 4 Casing i' iller had a -

chance to graJually seep into the internal vo;ds of the tendon.

The key to the whole system is the fully coating of the tendon and some initial penetration into the tenden bundle during the original pumping. Once the tendon is copted hot in this manner the Visconorust 2090 P-4, rso cooling 1 contracts but leaves a heavy film up to 20 mils or more on the tendon surface. This provides ample extended corrosion protection as seen now with over 20 years of Surveillance history without

, tondon corrosion problems.

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FEB-17-1932 11 FPm MG-gm NT E E NN it is recognized that during the surveillance operation there is a good chance of trapping air pockets in the trumpet when they refil: the tendon with the corrosion proventive, but again the tondon is coated. Trying to pump the Visconorust 2090 P 4 in one end of the tendon and out the other end, probably causes more harm then .

good, as the system was well coated ini+Jally and pressur! zing the system.to try and break through the solid Visconorust 2060 P-4 can possib!y force product through weak locations in the tendon sheathing and into the containment building, or blow vent caps or seats. Also pumping excessive product into the tendon could over till the system and not leave room for expansion when the whole system is heated up again during plant operation.

We thereio.e suggest that no att6ngt ce made to consider volds unless there definhely has been extensive leakage, The volume of casing iillor lost during surveillance should be pumped back into the systems from bcth ends of the tendon.

On tho 'U' shaped tendon of the hemispherical plants the dome vents should only be topped off onco, if needed, by pouririg in the casin overfill the system leaving no room for expans;on. g filter. Continually doing this would Allintroduction of Visconorust 2090 P 4 Cesing Filler back into the tendon system should be done with heated material at 15CfF minimum.

^ We would be very happy to further review the above discussion regarding the matter of volds, the operability cf the system, and the possible passags of casing fdier into the concreto t.wrounding the tendons. ot an ASME Committee meeting.

For your immediato Interest please note that the Visconorust 2090 P 4 Casing Filler, in i

use since 1974, has a considerably higher molting point (140'F) compared with the l original typo casing filler that flowed at 10$'F. Also since that time all surveillance work has used the Visconorust 2090 P 4 to replace the lower n,etting point casing tiller for refdl, which greatly assisted in raising the flow peint of the casing fiUar in the older systems. These factors havo helped in alleviating the leakags potential.

Sincerely, h)+!i' C.W. Novak CWN/rac n

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4 ENCLOSUCE 2 V0GTLE ELECTRIC GENERATING PLANT REQUEST TO REVISE TECHNICAL SPECIFICATION 4.6.1.6.1.d.2 10 CFR 50.92 EVALUATION Pursuant to 10 CFR 50.92, GPC has evaluated the proposed amendment and has determined that operation of the facility in accordance with the proposed amer,'nent would not involve a significant hazards consideration. The basis for this determination is as follows:

1. The proposed change does not involve a significant increase in the probabilitv c' co .mauences of an accident previously evaluated. -The proposed change only affects the requirement to measure the grease void fraction of the containment sheathing filler greasc, and therefore, will have no effect on the probability of any accident previously evaluated.

Furthermore, the remaining tendon surveillance requirements plus the proposed new requirement to replace at a minimum the grease removed during a surveillance will continue to ensure the capability of the tendcas to perform their safety function. Therefore, containment integrity will be maintained during and following any previously evaluated accident, trd the preposed change will have no effect on the consequences of such an accident.

2. The proposed change does not creat? the possibility of a new or different kind of accident from any accident previously evaluated. The proposed change Joes not introduce any new equipment it,to the plant or require any existing equipment to be operated in a manner different than that for which it was designed. Containment integrity will continue-to be maintained, and all initial and boundary conditions assumed for the accident analyses will remain the same.

3 The proposed change does 1ot involve a significaat reduction in a margin of safety. The basis for the exis+ing requirement is to ensure that the containment tendons are protected frem corrosion. However, the initial installation of the tendons plus the remaining surveillance requirements are adequate to ensure that the tendons are protected from degradation due to corrosion. Furthermore, considering the potential for damage-as a-result.of trying to measure the grease void fiaction, the margia of safety will be maintained under the proposed change.

Based on the above analysis, GPC has deternined that the proposed change to the Technical Specifications will not significantly increase the probability or consequences of ar accident previously evaluated, create the possibility of a new cr different (ind of accident from any accident previously evaluated, or involve a significant reduction in a margin of safety. Georgia Power Company therefore concl; des that the proposed change meets the requirements of 10 CFR 50.92(c) and does not involve a significant hazards consideration.

C2-1 a.

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