Conclusion
Graphites and C/C Composites for Generation IV Nuclear Reactors

Graphite has been used right from the start of the nuclear industry, both in research reactors and in power generation applications (1^re and 2^nde generation reactors), as it is a good neutron moderator, has good mechanical and thermal properties even at high temperatures, and resists neutron damage (irradiation) well. Of the six 4th generation reactor concepts, two use graphite for neutron moderation and core structure: the VHTR (Very High Temperature Reactor) and the MSR (Molten Salt Reactor).

Despite its good resistance to irradiation, the properties of graphite nevertheless evolve with neutron damage: mechanical properties (modulus and strength) increase, then fall, thermal conductivity decreases and dimensional changes occur in graphite blocks, which generally begin to contract in one or more directions, before exhibiting volume expansion in the case of severe damage...