Load Follow Simulations for the LDR-50 District Heating Reactor Using the Kraken Computational Framework

In 2020 VTT Technical Research Centre of Finland launched the development of a new low-temperature, low-pressure SMR, designed to produce heat at 65-120 ^◦C temperature for the purpose of district heating. The work is part of an effort to de-carbonize the Finnish heating sector, which is currently a major source of CO ₂ emissions. Reactor design has been carried out using computational tools developed at VTT, most importantly the Apros process simulator and the Kraken core physics framework. This paper presents load follow simulations carried out for the most recent core design. The core physics calculations also serve as an important test case for new features implemented in the Ants nodal neutronics code. It is shown that the reactor performs as expected in a calculation case where the boundary conditions are constantly changing, following historical operating data of a real district heating network. However, the results do suggest certain improvements in the methodology used for control rod movement and the calculation of reactivity coefficients.