Designing an Irradiator for the In-Reactor Testing of Absorbing Materials of Nuclear Reactor Control Bodies

The Atomic Reactor Research Institute is developing the design of an irradiator for conducting in-reactor tests of neutron-absorbing materials in nuclear reactor control systems. Dysprosium titanate is chosen as the absorbing material due to its high chemical and thermal stability, along with its enhanced corrosion and radiation resistance. The irradiator’s design consists of a suspension with a flange, a working section where the sample with the absorbing material is placed, a flow separator, and an absorbing screen. The flow separator is made of 12Kh18N10T stainless steel. The absorbing screen, designed to reduce the proportion of thermal neutrons in the spectrum, consists of two cylinders made of boron steel and aluminum, encased in 12Kh18N10T stainless steel. Neutron-physical calculations are made using the MCU-FR code, in addition to thermal-hydraulic calculations of the RD design obtained using the SolidWorks software. The calculations show that using a screen made of boron steel and aluminum allows the ratio of fast and thermal neutron flux to be adjusted during in-reactor tests of the absorbing materials. Results from thermal-hydraulic calculations show that using high-temperature loop installation VP-3 of the SM-3 reactor under conditions of forced circulation ensures the required temperature regime for irradiating a sample with dysprosium titanate in the third row of the SM-3 reflector.