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Leak Before Break Design Methods and its application to Indian Nuclear Power Plants

November 16 @ 3:00 pm - 4:00 pm

One of the hypothetical design basis events considered in the design of Pressurized Heavy Water Reactor (PHWR) and Pressurized Water Reactor (PWR) is instantaneous Double Ended Guillotine Break (DEGB) of the largest heat transport piping. This concept was originally initiated for sizing of the PWR containments and Emergency Core Cooling System (ECCS). However , due to seismic considerations,regulatory philosophy for the design of piping system tended to shift the DEGB from a hypothetical accident to one having increasing credence requiring provisions of protection against DEGB. As a result of this DEGB criterion many pipe whip restraints have been installed to arrest the dynamic effects associated with catastrophic pipe rupture e.g. pipe whip , jet impingement and decompression waves. However,experience over the year have shown that these devices result in several problems e.g. ISI leading to additional radiation exposure to maintenance personnel , increased
heat loss and unanticipated thermal expansion stresses. Therefore, the additional protection provided by these devices was questioned. As a results , the concept of Leak Before Break emerged. The concept of LBB is now widely used to design the primary heat transport (PHT) piping system of nuclear power plants. This approach has been used in design of the 540 MW(e) , Tarapur Atomic Power Station ,operating in Tarapur Mumbai. The LBB concept demonstrates through fracture mechanics analysis that there is negligible chance of any catastrophic break of PHT piping without giving prior indication of leakage. This involves fracture mechanics testing of specimens, full scale testing of straight pipes, elbows ; branch pipes and elastic- plastic fracture mechanics analysis of PHT pipings.Discipline/Coordinating Entity: Mechanical Engineering


November 16
3:00 pm - 4:00 pm
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