SPECTRAL SHIFT ROD FOR THE BOILING WATER-REACTOR

A Boiling Water Reactor core concept has been proposed using a new fue l component called spectral shift rod (SSR). The SSR is a new type of water rod in which a water level is formed during core operation. The water level can be controlled by the core recirculation flow rate. By using SSRs, the reactor can be operated with all control rods withdraw n through the operation cycle as well as that a much larger natural ur anium saving is possible due to spectral shift operation than in curre nt BWRs. The steady state and transient characteristics of the SSRs ha ve been examined by experiments and analyses to certify the feasibilit y. In a reference design, a four times larger spectral shift width as for the current BWR has been obtained.