Control drums, placed around the perimeter of the reactor core, are being evaluated as an alternative to the traditional use of control rods for active reactivity control. With the smaller effective core diameter, drums accomplish through rotary actuation what control rods do through vertical manipulation; and, with a soluble chemical neutron absorber (boron based) in the reactor coolant, provide an overall reactivity control program. The cost benefit in using drums could be significant for the reactor vessel.