Speaker
Description
To determine the power produced in a fusion device, an accurate estimation of the neutron yield is necessary. It is a fundamental operational quantity and, being linked to plasma performance parameters, it is an important measure of fusion success. The neutron yield is also needed to support the operational safety case and is the prime input to operational and maintenance doses.
A second Deuterium-Tritium Experimental Campaign at JET is planned for 2020; in which up to 1.7∙1021, 14.1 MeV neutrons will be produced. They will be measured by two neutron yield monitoring systems installed at JET: fission chambers (KN1) and activation system (KN2). These systems were absolutely calibrated in 2017 using a characterized ING-17 14 MeV neutron generator (NG) as the calibration neutron source. The neutron emission rate of the NG was measured based on monitoring foil activation measurements. For the NG characterization campaign, the absolute neutron emission rate of the NG was estimated with a total uncertainty equal to ±4.0%, while the neutron emission rate during the in-vessel calibration was assessed with an uncertainty ranging from 4.7% for Nb to 6.9% for Al.
An independent analysis of the activation measurements used to determine the neutron emission rate of the NG is presented in this paper. The neutron emission rates of NG from monitoring activation results were obtained using a detailed MCNP model of the NG and its neutron source properties. In the second case they were calculated using the FISPACT-II code with neutron flux spectra calculated by MCNP code. Calculated values of neutron emission rate were compared to values estimated based on the activation measurements. In the case of a NG characterization campaign the discrepancy between calculated and measured values of neutron emission rate was 3%. This discrepancy was lower for the in-vessel calibration, in the region of 1%.
