Fusion yield measurements on JET and their calibration

• Published in: Nuclear engineering and design Vol. 246; pp. 185 - 190
• Main Authors: Syme, D.B., Popovichev, S., Conroy, S., Lengar, I., Snoj, L.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2012
• Subjects: Activation; Calibration; Mathematical models; Neutron detectors; Neutron emission; Nuclear engineering; Nuclear fusion; Nuclear power generation; AS; TF; OS; RH; JET; ITER; FC
• ISSN: 0029-5493; 1872-759X; 1872-759X
• DOI: 10.1016/j.nucengdes.2011.08.003

► JET neutron calibrations – methods and status. ► New calibrations – methods, deployments and contingency arrangements. ► Neutronics calculations in support – models and examples. The power output of fusion experiments and fusion reactor-like devices is measured in terms of the neutron emission rates which relate directly to the fusion yield rate. Determination of such parameters requires a set of absolutely calibrated neutron detectors. At JET, the Fission Chamber neutron detectors were originally calibrated some 20 years ago by performing a set of in-situ calibrations using neutron sources and the absolute calibration has been maintained since then by cross calibrations against Activation System measurements. After this elapsed time and a succession of changes to the internal and external JET structures, the JET neutron yield calibration needs re-measurement. The purpose of this paper is to give an overview of the arrangements being developed to allow a new calibration to be made. A new, more detailed, calibration is being provided by means of an engineering programme of development of the robotic tools which will allow safe and accurate deployment of a strong 252Cf source for the measurements. It is led by a scientific programme which seeks to better understand the limitations of the calibration, to optimise the measurements and other provisions, to provide corrections for perturbing factors and to ensure personnel safety and safe working conditions. Much of this work is based on an extensive programme of Monte-Carlo calculations. These include the updating of previous JET models to provide continuity of comparison with previous understanding, the provision of fast models for side effect estimation and the development of a new more detailed JET model which will allow comparisons with the older more homogeneous model while coping with the demands of the new calibration.