Sensitivity Studies on the Influence of Shutdown Control Assembly Banks Arrangement in Rod Control Assembly Banks Withdrawal From a Subcritical Condition

A rod cluster control assembly (RCCA) withdrawal from a subcritical condition (RWFS) will lead to an uncontrolled reactivity addition to the core resulting in a power excursion. Such a transient is a limiting case among the moderate frequency incidents in CPR1000 power plant. In this paper a sensitivity study on the arrangement of shutdown control assembly banks which may be have some differences between two power plants have been preformed. The calculation method and main hypothesis used are also briefly presented. The study shows that if all the shutdown assembly banks are located outside the core in hot shutdown state, the radial enthalpy rise factor (FΔH), the maximal reactivity insertion rate and maximal thermal power in RWFS accident is lower than the base case defined as the one with some shutdown banks in the core, while the trip reactivity insertion rate values introduced when trigger reactor trip is bigger than the base case.Copyright © 2013 by ASME