Embrittlement of Steels in Neutron Irradiation Environments

ONR is seeking to engage one of the Technical Support Contractors (TSC) appointed on Lot 2 of its Technical Support Framework. DDRs developed using data compilations from reactors in different countries show apparently national biases in the effects of irradiation in that a DDR developed from surveillance data from that country's fleet will predict the behaviour of that fleet well, but will show both increased uncertainty and bias with respect to another country's fleet. An understanding of the causes underlying these apparently national biases is essential in developing and maintaining Safety Cases for RPV materials. This is already the case for SZB, but will become more acute as GDA designs begin construction. This will become still more of a pressing problem with Advanced Reactor Designs which utilise materials outside of the current operating experience in terms of doses, neutron energy spectra and irradiation.

There is a need for the UK regulator, therefore, to develop an understanding of the irradiation embrittlement to maintain understanding for operating fleet and to develop understanding for future foreseeable challenges.