Neutronics experiments and analyses in preparation of DT operations at JET

Shutdown dose rate neutronics experiment during high performances DD operations at JET

“…During the last decades, Rigorous Two-Step (R2S) [4][5][6] and Direct One-Step (D1S) [7] tools based on MCNP Monte Carlo code [8] have been developed and extensively applied for ITER assessment. The prediction capabilities of these tools have been verified through several computational and experimental benchmarks and in particular, SDR benchmark experiments have been conducted at JET since 2005 [2,[9][10][11]. The results of the past benchmark experiments confirmed that the available calculation methodologies for shutdown dose rate assessments were in good agreement and capable of reproducing the measured quantities in the examined temporal range in a tokamak configuration within the experimental uncertainty margin.…”

“…Shutdown dose rate was measured using commercial spherical air-vented ionization chambers (PTW type TM32002,  140 mm) procured by ENEA and KIT. These dosimeters were selected on the basis of the following requirements and operative conditions: low activation, large range of operation (from background to 30 mSv/h, according to pre-analysis), high efficiency, long term stability, flat energy and dose response, isotropic angular response, radiation resistance (up to 10 15 n/cm 2 total fluence), compact dimensions, remote control and acquisition and compliancy with JET regulation [2]. Before the installation at JET, accurate calibration under X and gamma sources and preliminary irradiation tests under DT neutrons at the Frascati Neutron Generator (FNG) were performed [12].…”

“…In the frame of the EUROfusion Consortium, the Work Package DT Technology (WPJET3) was launched in 2014 to exploit the unique 14-MeV neutron yields produced in DTE2 (up to 1.7 × 10 21 neutrons) at Joint European Torus (JET) and the use of tritium to validate codes, assumptions, models, procedures and data currently used for ITER [1]. The NEXP subproject is devoted to the preparation of neutronics benchmark experiments for validating the neutronics codes and tools for ITER nuclear analyses to predict the neutron flux along streaming paths and dose rates at the shutdown due to activated components [2,3]. In particular, the shutdown dose rate (SDR) assessments is a key issue for ITER design and the use of qualified and validated codes and nuclear data are essential to ensure the reliability of shutdown dose rate predictions.…”

“…The efforts recently carried-out in the new experiment during Deuterium-Deuterium (DD) campaign in preparation for future DTE2 are mainly devoted to reduce the experimental uncertainties and improve modelling accuracy. Furthermore dose rate measurements are now complemented with neutron fluence measurements during operation and gamma spectra at shutdown so as to identify the dominant radionuclides [2]. The experimental assembly and measurements analyses performed in the last 2016 DD benchmark are presented and discussed in this paper.…”

Rigorous-two-Steps scheme of TRIPOLI-4® Monte Carlo code validation for shutdown dose rate calculation

“…Improvement of the R2S scheme are planned: to accelerate the calculation (MENDEL parallelization), to propagate the statistical error of the first step and to handle different materials in a mesh-cell. Extended validation exercises will be carried out with the Frascati Neutron source Generator SDR experiment [11] and the JET SDR measurement [23]. TRIPOLI-4 ® R2S should be used in near-term for ITER neutronic analysis at CEA [24].…”