Impact of Corrosion Product Deposition on CANDU-SCWR Lattice Physics

Abstract

The CANDU(R) supercritical water-cooled reactor (CANDU-SCWR) is a pressure tube reactor intended to operate with a coolant pressure of 25 MPa and temperatures ranging between 350°C (core inlet) and 625°C (core outlet). Along the length of a fuel channel, there is a drastic decrease in the coolant density and dielectric constant, which is expected to result in a rapid decrease in the solubility of corrosion products. Therefore, it is anticipated that corrosion product deposition onto the cladding and liner in an SCWR fuel channel will be much greater than in conventional water-cooled reactors operating below the critical point of water. While optimized materials selection and chemistry control strategies may mitigate corrosion and corrosion product deposition to some degree, it may not be possible to completely eliminate corrosion product deposition within SCWR fuel channels. Corrosion product deposition on fuel cladding will have a negative impact on the neutron economy of the CANDU-SCWR because of parasitic absorption of neutrons within the deposited material. In this paper, lattice physics calculations are used to assess the impact of corrosion product deposition on fuel exit burnup, based on corrosion product deposition rates estimated for prototypical SCWR conditions.