DERMAGA - An alternative tool to generate random patterned-channel-age in CANDU fuel management analyses part I: Method development

In any reactor physics analysis, the instantaneous power distribution in the reactor core of any power reactor, including CANDU-type reactor, can be calculated when the actual bundle-wise burnup distribution is known. Considering the fact that CANDU utilizes the on-power refuelling to compensate for the reduction in reactivity due to fuel burnup, in the CANDU fuel management analysis, snapshots of power and burnup distributions can be obtained by simulating and tracking reactor operation over an extended period using various tools such as the *SIMULATE module of the reactor fuelling simulation program (RFSP) code. However, for some studies, such as an evaluation of a conceptual design of a next generation CANDU reactor, the preferred approach to obtain a snapshot of the power distribution in the core is based on the patterned-channel-age model implemented in the *INSTANTAN module of the RFSP code. The objective of this approach is to obtain a representative snapshot of core conditions quickly. Presently such patterns could be generated by a program called RANDIS which is implemented within the *INSTANTAN module. Presented in this paper is an alternative approach to derive the patterned-channel-age model where an optimization algorithm is utilized to find patterns which produce representative power distributions in the core. In the present analysis, the genetic algorithm (GA) technique has been successfully utilized to find a quasi-optimal patterned-channel-age. This paper is Part I of a two-part paper which highlights the development of this alternative method for generating patterned-channel-ages.