As part of the GIROSCOPE EU-funded project we have undertaken to perform source term calculations. To do so reliably suggests running long series of Monte Carlo computations for radiation field dynamics, with as small time steps as possible. The proposed operational scheme for the reactor, where a advanced new fuel technologies are to be used, means that a set of extra series need to run in order to reach steady operational state. We estimate that we need to run in the order of 5 time steps per month, with 18 months in a fuel cycle. To reach steady state operations of a reactor, we would have to run 4 cycles. For reliable statistics we require computational resources, beyond what a workstation can provide. Our previous performance test project naiss 2025/22-1015 has shown Dardel to be a reliable and fitting machine for our needs. We have an established procedure to compile required software, and run-scripts are setup and done. The algorithm we use is a essentially a loop over a two-step process: 1. A series of fixed time MC-transport runs are performed which emulate the active control of a reactor keeping it running. This yields a radiation field. 2. Using the radiation field we may estimate transmutation, fission product generation, radioactive decay etc. through solving a set of 1st order differential equations.