4/Describe the difference between a grey neutron absorbing material and a black neutron absorbing material. Why could a grey neutron absorbing material control rod be preferred over a black neutron absorbing material control rod?

5/ The experimental determined differential rod worth of a control rod is represented by DRW = -x²/36 + (5/3)x pcm/in where X=0 is the bottom of the core and 60 inches is the top of the core.

Determine the amount of reactivity added when the control rod is inserted from 45 to 30 inches.

6/The total amount of reactivity added when moving a control rod from 5 inches to 15 inches was 120 pcm. Find the equation for Differential Rod Worth (DRW) in this region, assuming the DRW is a linear function of rod height, x, where X=0 is the bottom of the core.