The stellarator Wendelstein 7-X (W7-X), presently under construction at the Max-Planck-Institute for Plasma Physics in Greifswald, will be equipped with a set of neutron monitors to measure the total annual neutron emission for official documentation and to provide information for plasma diagnostics purposes. The authors performed MCNP calculations to design and optimise the moderator geometry of the monitors to exhibit a nearly energy-independent response as well as particular angular responses for one central and two peripheral monitors. The monitors were designed with up to five neutron detector tubes with different sensitivity to thermal neutrons to cover the expected neutron emission rates of W7-X from 10(11) s(-1) to 10(16) s(-1). A prerequisite for the determination of the neutron emission produced by a D-D plasma is an in-situ calibration of the neutron monitors. Such a procedure requires a MCNP simulation of the entire geometry of the W7-X stellarator. In a first benchmark experiment during the assembly phase of W7-X, the validity of the W7-X MCNP model was tested.
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