Fast-neutron nuclear reactor in which at least one moderator element is incorporated in assemblies of the reactor

摘要

In a fast-neutron nuclear reactor, it is proposed to introduce a moderator element such as B<11>4C. The neutron spectrum is thus softened, which makes it possible to reduce the vacuum coefficient and increase the Doppler constant. The increase in reactivity which occurs in the event of coolant loss is thus reduced at all points of the core of the reactor. The moderator element can be mixed with the nuclear fuel, or with a material of a different nature, in a homogenous form or placed, in heterogenous form, in specific rods (needles) (14) distributed among the rods (12) containing the nuclear fuel or another material.