Neutronic analysis for detail design of the microfission chamber for ITER neutron flux monitor

Ishikawa, Masao; Takeda, Keigo*; Kondoh, Takashi; Shimada, Takahiko

A Microfission Chamber (MFC) provides time-resolved measurements of global neutron source strength and fusion power in ITER. MFCs will be installed behind blanket modules at upper and lower outboard position due to interface considerations with other equipment and the vacuum vessel. Since the location of the MFC is close to the Plasma, sensitivities of MFCs vary due to the change of the plasma position. In this study, a method to obtain neutron source strength accurately has been investigated using Neutron Transport Analysis Code (MCNP) if the plasma position would be changed. As a result, it was found that the linear combination of the MFCs at the upper and lower outboard position, in which weight of change of sensitivity of each MFC due to the change of the plasma position, can keep the output consist within error of 3%.