In-vessel calibration of JET neutron detectors: Comparison of methods of neutron emission rate determination

Highlights: • Two methods of neutron emission rate determination have been described. • The neutron emission rates of neutron generator have been cross-checked. • The impact of using different cross section libraries has been investigated. -- Abstract: A second Deuterium-Tritium Experimental Campaign (DTE2) at JET is planned for 2020 in which up to 1.7∙10²¹ DT neutrons could be produced. They will be measured by two neutron yield monitoring systems installed at JET: firstly a fission chamber system (KN1) and secondly the activation system (KN2). These systems were absolutely calibrated in 2017 using a characterized ING-17 DT neutron generator (NG) as the calibration neutron source. The neutron yield of the NG during this calibration experiment was measured at defined positions from a number of dosimetric foil activation measurements. The neutron emission rates of the NG were derived using these measurements together with results from a detailed MCNP model of the NG and its neutron source properties, and from two calculation methodologies to account for nuclide creation and decay during irradiation and cooling times. The method of neutron emission rate determination based on activation measurements and FISPACT-II simulations is described here. The comparison of results obtained for two methods of neutron emission rate determination is also presented and discussed. The impact of the applied cross section library on the computed neutron emission rate of the NG has been investigated and presented in this paper.