Recent developments in nuclear heating measurement methods inside the OSIRIS reactor

摘要

Nuclear heating inside a Material Testing Reactor (MTR) needs to be known in order to design and to run irradiation experiments that have to fulfill target temperature constraints. To improve the incore nuclear heating knowledge of the French OSIRIS reactor operated by CEA, an innovative calorimetric system CALMOS (French acronym for CALorimetre Mobile OSiris) has been studied, manufactured and tested. This device can be inserted in any in-core experimental location. It is based on a mobile probe moving axially along the core height. First tests of this new probe, offering several ways for the heating evaluation, were performed in the reactor periphery. Then, two complete prototypes dedicated to incore measurements (calorimeter and the associated displacement system) were designed and tested during several reactor cycles. This paper presents a comprehensive analysis of all the results collected during the measurement campaigns carried out between 2013 and 2015 with these new prototypes in various reactor conditions. A comparison is made with previous calorimeters and obtained advantages are emphasized. This new calorimeter has been designed as a real operational measurement system, well suited to characterize the radiation field inside an MTR reactor.