In this project the focus has been on the system for recombination at Oskarshamn 2. The recombining systems have on several occasions switched paths due to low pressure before the last ejector that?s feeding the recombiner. Of the mentioned reason, events and several measuring points have been analyzed in this report since the installation of the recombining systems.In order to prove theories and demonstrate what may be the cause of this problem, we used heat balance calculations by the program Probera. Using the program, we can demonstrate that the catalytic process does not reach the desired temperature with the amount of combustible substance.