Pulse neutron subcritical K/sub EFF/ measurements on water flooded arrays of fuel rods

The pulsed neutron source technique has been utilized at the Pacific Northwest Laboratory for some twenty years for measurement of subcritical reactivities of a variety of fuel systems. One area of application has included measurements of subcritical reactivities of water flooded arrays of fuel rods. This report summarizes these measurements. The theory behind the measurement process is reviewed and the instrumentation of the measurement system discussed. Also, four experiment programs are described in detail, illustrating system use and flexibility. Some changes are suggested for system improvements to speed up data collection and data reduction, and some possible areas of future application of the method are described