In 2019 JET carried out a very successful Deuterium-Deuterium campaign, referred to as C38, producing a total of 3.751019 DD neutrons. During this campaign, a series of experiments were implemented to record the neutron fluence at positions close and far from the source and along shielding penetrations. Measurements were performed using LiF Thermoluminescence Detectors (TLDs) and sets of high purity cobalt, silver and tantalum disc-shaped activation foils, placed inside high-density polyethylene moderators.
Monte Carlo N-Particle (MCNPv6.1) code was used by CCFE to calculate the neutron fluence at 22 detector locations in JET hall. The neutron fluence was calculated for each individual TLD and activation foil as positioned inside the polyethylene moderator, using a detailed JET 360-degree model. These demanding calculations were made computationally feasible due to the employment of AutomateD VAriaNce reducTion Generator (ADVANTG) code developed by ORNL.
The results of the calculations were compared against the experimental results derived from the TLDs and the activation foils, in terms of neutron fluence and reaction rates, and a satisfactory agreement was observed.
The results of the present work contribute to the verification of ADVANTG software for Monte Carlo simulations of complex geometries, such as those encountered in a tokamak, most particularly at positions far from the plasma source, where no other computation method can provide reliable results. The experiments and calculations will be repeated for the upcoming Tritium-Tritium and Deuterium- Tritium JET campaigns.