reaction occurring as there are more neutrons going through an area per unit time. Reactor vessel wall neutron fluence A reactor vessel of a typical nuclear power plant (PWR) endures in 40 years (32 full reactor years) of operation approximately 6.5×1019 cm−2 (E > 1 MeV) of neutron fluence. Neutron flux causes reactor vessels to suffer from neutron embrittlement. See also Neutron radiation Neutron transport References Flux