HTGR Knowledge Base

Conference Article: Application of A Leak Before Break Procedure To A HTGR CROSS-DUCT

Abstract

The application of Leak Before Break procedures to some components of High Temperature Gas cooled Reactors (HTGR) should allow to reduce the consequences of depressurization transients, in combination with the use of defect assessment methods and Non Destructive Controls for the pressure vessel. A first application of the RCC-MR A16 Leak Before Break (LBB) procedure to the cross-duct of a HTGR project is presented in this paper. A parametric study has been performed, taking into account several detectable flow rates and different in service and seismic stresses. It has been found that the length of detectable crack can be smaller than the critical crack, but the result depends on the hypotheses of the method, so that further validations are needed as well as improved seismic calculations. Some other planned improvements of the analysis are also described. In any cases, it is shown that the evaluated detectable crack should not lead to a rapid depressurization, even if a seism arises just before the shutdown of the reactor. Moreover, for this particular event, the crack appears to have an equivalent breach diameter of 2 mm during the seism. It means that the leak should be covered by helium auxiliary feeding system of the HTGR.

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Reference:

Proceedings of the Conference on High Temperature Reactors, Beijing, China, September, 22-24, 2004

International Atomic Energy Agency, Vienna (Austria)

HTR-2004, pp:1-9