Fusion Power Measurement Based on16O(n, p)16N Reaction in Flowing Water

A fusion power monitor with water flow based on 16O(n, p)16N reaction has been designed for ITER. Irradiation ends will be installed in the filler shielding module between the blanket modules at the horizontal ports. The Uγ-ray counting stations will be installed on the upstairs of the pit. The distance between the irradiation end and the counting station is ~20 m. We evaluated the performance of this fusion monitor using by MCNP-4b code with the JENDL 3.2 library, where the vacuum vessel, blanket modules, filler shielding modules and first walls were modeled 3-dimensionally. The reaction rate of l6O(n, p)16N was calculated not only at the irradiation end but also along the transfer line, which showed that the temporal resolution would be less than 100 ms including turbulent diffusion effect for the flow velocity of 10 m/s. With the flow velocity of 10 m/s, this system can measure the fusion power from 50 kW to 1000 MW of the ITER operation. Also the calculation shows that the reaction rate is relatively insensitive to the change of the plasma position.