ML20210B502

SER Concluding That Fuel Transfer Tube Expansion Joints Subj to Type B Testing When Part of Containment Pressure Boundary

ML20210B502
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	09/15/1986
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20210B500	List: ML20210B495 ML20210B502
References
TAC-61018, NUDOCS 8609180098
Download: ML20210B502 (2)

Text

-__ - _ _ _ -_ _ _ _ _ - _ _ - -_-_ -

..  ; Enclosura SAFETY EVALUATION REPORT ENGINEERING BRANCH TYPE B LEAK TESTING OF FUEL TRANSFER TUBE EXPANSION JOINTS By memorandum dated March 17, 1986, Region V requested a clarification of the requirements for local leak rate testing of fuel transfer tube expansion joints at PWR plants. The specific example cited was the Trojan Plant.

Appendix J to 10 CFR 50, paragraph II. G., states, in part, that Type B (local g leakage rate) tests include piping penetrations fitted with expansion bellows.i.

Although there may be some argument as to whether or not the fuel transfer tube penetration in a typical PWR is a " piping penetration," the staff takes the position that the fuel transfer tube expansion joints are included in the definition and should be subjected to Type B testing, when the expansion joints form part of the containment pressure boundary. The general intent of the Appendix J Type B and C testing program is to locally test all contair. ment penetrations, as they are the most likely paths for containment leakage during an accident. Certain penetrations are excluded, such as spare penetrations

. and seal-welded doors, when these are completely welded shut, because they offer the same low-leakage barrier as a welded steel containment liner or (for a free-standing steel containment) containment wall. Since containment penetrations are more likely to leak than the containment wall, they are tested more frequently (every two years as opposed to approximately every 31/3 years i for Type A (integrated leak rate) tests).

1 8609180098 860915 PDR ADOCK 05000344 P PDR

. . 2

., .1

. 2 ,

Furthermore, in a case like the Trojan plant, absent a Type B test, the expansion joint ins!de containment may be leaking freely, and the Type A test wcuid not . detect this if the expansion joints outside containroent were leak-tight. Cepending solely en the cuter joirts is unacceptable, as they ciay not be fully qualified as contain;nent isolation barriers. Thus, only a Type B test will properly test the assembly. In addition, if the inner joint were to fail, the two expansion joints outside containment could limit containment o 6

$ leakage if they were leak-tight. A Type 8 test of1 the innee joint vould 4

presumably be performed by pressurizing the voluine between the inner and outer pipes of the penetration; this would also test the out'er joints at the same time. Although the cuter joints are not required to be considered to be containment isolaticn barriers, it would be prudent to check their integrity along with testing the inner joint. The outer joints afght otherwise never be tested, as they are not normally : exposed to the Type A test pNsecre, ar Therefore, the staff concludes that fuel transfer tube expansion joints are recuired to be-Type B tested, when the expansion joints form part of the containmer,t pressure boundary. In the case of the Trojan plant, the expansion joint inside containmer.t would thus be subject to Type 2 testing.

I _