Analysis of the use of flux suppression fixtures for Indian Point unit 3, cycle 7, and future cycles

The CASMO-2E and MBS programs have been used to obtain a qualitative evaluation of several means of reducing the fast neutron flux incident on the reactor vessel and thus increasing its useful life. A more detailed calculation using the DOT program will be performed to provide a quantitative evaluation at New York Power Authority (NYPA). The work described in this paper examined the effect of introducing different neutron absorbers into the assemblies closet to the reactor vessel. These are the eight twice-burned assemblies located in the northeast, northwest, southeast, and southwest corners of the reactor core. The absorbers considered were Ag-In-Cd (20 rods per assembly), hafnium (20 rods per assembly), stainless steel (20 rods per assembly), fresh wet annular burnable absorbers (WABA) (20 and 16 rods per assembly). These corner assemblies each have an average exposure just over 30 MWd/kg U so that the CASMO-2E depletion calculations with the absorbers inserted were started at 30 MWd/kg U