Neutron Fluence and Atomic Displacement Rates for Graphite Irradiations

A brief review of the theoretical and practical bases for the correlation of graphite irradiation data obtained in different experimental facilities has been used in the derivation of relationships for conversion of the fluence units Φ_{(E> 0.18MeV)} and Φ_{(DIDO eq.)}, which have previously been most widely used for reporting graphite irradiation data, to the new international unit, Φ_G, “equivalent fission fluence for damage in graphite.” Using the Thompson and Wright form of the atomic displacement function and the activation cross sections recommended by the International Nuclear Data Committee, with appropriate corrections for differences in cross sections used previously, the recommended conversion relationships are as follows:Φ_G = <1.18 Φ _{(E > <0.18 MeV)} <and Φ_G = <1.77 Φ_{(<DIDO eq.)}.