Abstract

An accelerator-driven subcritical breeding reactor is operated with a neutron multiplication coefficient as large as possible in order to require a small input power from the accelerator, reducing its dimension and hence its cost and complexity. The beam-generated spallation neutron yield then becomes comparable to the fraction of delayed neutrons from the fissioned elements. This can be exploited to ensure an accurate on-line determination of the reactivity. Resulting changes can be adjusted with the help of neutron absorbing control rods and/or variations of the proton current. In addition, the temperature variations during operation can be continuously monitored and adjusted in order to avoid that the subcritical systems approaches too closely the (delayed) criticality condition and that the neutron multiplication coefficient remains within acceptable limits.

IPC Classes  ?

• G21C 1/30 - Subcritical reactors
• G21C 7/34 - Control of nuclear reaction by utilisation of a primary neutron source
• G21D 3/10 - Regulation of any parameters in the plant by a combination of a variable derived from neutron flux with other controlling variables, e.g. derived from temperature, cooling flow, pressure