Shutdown dose rate benchmark experiment at JET to validate the three-dimensional Advanced-D1S method

The paper describes a new benchmark, performed as a preliminary experiment on JET tokamak during the last shutdown. Dose rate has been measured with different dosimeters along the axis of the main horizontal port of Octant 1, from the plasma centre to 1 m outside the port at various times after shutdown. The activation dose from the horizontal neutron camera, moved outside the torus hall during the shutdown, has also been assessed. The measured values have been compared with dose rates calculated using an Advanced-D1S method in which new computation capabilities have been introduced, such as dose rate spatial mesh map and automated time behaviour.Measurements along the axis of the horizontal port are well predicted by the calculation. With few exceptions, the D1S estimation is within the error of the measurements. The activation of the horizontal camera is underestimated by a factor of 2. However, more accurate measurements are needed to reduce the uncertainties.The Advanced-D1S method, the results and implications of the benchmark are presented and discussed.

► Shutdown dose rate benchmark experiment has been conducted at JET.
► First experiment so long after shutdown.
► Measurements along the middle axis of horizontal port and survey of KN3 system.
► Advanced-D1S method has been developed and applied to calculate shutdown dose rate.
► Advanced-D1S well reproduces the measured quantities in the examined temporal range.