2-D Evaluation of Bred Tritium Using Neutron Imaging Plate

Abstract

Tritium breeding performance of a fusion blanket is a key parameter for the self-sufficient fueling of a fusion reactor, and thus designed to validate the performance of a neutronics experiment. Measuring the 2-D distribution of bred tritium is challenging via conventional methods such as $\beta $ -ray counting from an irradiated lithium sample using a liquid scintillation counter (LSC) and a single-crystal diamond detector with a thin 6LiF film, because they are point detectors which require many measurements. In this article, 2-D distribution of the low quantity produced tritium was evaluated with a neutron imaging plate (NIP) with a Gd convertor by estimating the loss of neutrons via a capture reaction by Li. Deuterium–deuterium (DD) fusion neutrons were generated using a compact fusion device at an average neutron production rate of $1.5 \times 10 ^{5}$ n/s by applying high voltages. A neutron image with “shadows” projected by thermal neutron capture reactions of 6Li(n, $\alpha$ ) and 10B(n, $\alpha$ ) was successfully obtained. The experimentally evaluated values were confirmed to be consistent with the total number of capture reactions calculated using a neutron transport code. The results suggest that the approach could be a facile method for the 2-D evaluation of bred tritium.