Purpose of experiment

The void coefficient of reactivity is one of the most important coefficients of reactivity for safe reactor operation. The JSI TRIGA reactor is equipped with an electro-pneumatic system with which air can be injected into the reactor core to simulate void formation through boiling. The purpose of the experiment is the measurement of the magnitude of the void coefficient as a function of the radial location in the reactor core.

Outcome / What you will learn
Students will:
  1. observe the change in reactivity caused by the presence of air bubbles in the reactor core
  2. understand the magnitude and sign of the reactivity coefficient, depending on the location in the reactor core where air bubbles are injected

The task of the exercise is to measure the void coefficient of reactivity by introduction of void into several different positions in the core. The total volume of the voids is estimated on the basis of the flow rate, which is measured by the electro-pneumatic system. The magnitude and sign of the void coefficient of reactivity is determined and visualized on the spot, in dependence on the position on the reactor core.

Exercise No. 6: Control rod worth calibration