Experimental investigation of thermal hydraulic limits of BWR RCIC system operation under long-term operation Conference Paper uri icon

abstract

  • © Copyright (2015) by American Nuclcar Society All rights reserved. The Reactor Core Isolation Cooling (RCIC) System in Boiling Water Reactors with the Mark I containment uses a turbine-driven pump to provide makeup water to the reactor core in containment isolation events. It requires minimal electrical power in order for the controller to operate the system. As a result, it had previously been expected to fail when the station batteries deplete during Station Blackout scenarios - nominally by 4-8 hours in current safety analyses. However, the system has been observed to operate beyond battery depletion; in the accidents at Fukushima Daiichi, the RCIC System was able to operate long after the loss of all AC and DC power. To obtain a better understanding of the RCIC System's operational limits, an experimental facility was constructed and operated at the Laboratory for Nuclear Heat Transfer Systems at Texas A&M University. The capacity for significant, perhaps limiting, thermal stratification to occur in the Suppression Pool as a result of prolonged RCIC System operations was confirmed. Such stratification is highly dependent upon operational conditions and turbine exhaust sparger design. In cases of severe thermal stratification, the apparent thermal capacity of the Suppression Pool can be effectively reduced, and lower regions of the pool would have limited - if any - heat absorption. With reduced steam condensation from the RCIC turbine, the containment could pressurize before the bulk of the pool is saturated.

author list (cited authors)

  • Solom, M., Vierow, K., & Nosek, A.

publication date

  • January 2015