Fusion Neutronics Experiments Research Articles

Benchmark test of TRIPOLI-4 code through simple model calculation and analysis of fusion neutronics experiments at JAEA/FNS

In order to examine a basic performance of the TRIPOLI code, two types of analyses were carried out with TRIPOLI-4.4 and MCNP5-1.40; one is a simple model calculation and the other is an analysis of iron fusion neutronics experiments with DT neutrons at the Fusion Neutronics Source (FNS) facility in Japan Atomic Energy Agency (JAEA). In the simple model calculation, we adopted a sphere of 0.5m in radius with a 20MeV neutron source in the center and calculated leakage neutron spectra from the sphere. We also analyzed in situ and Time-of-Flight (TOF) experiments for iron at JAEA/FNS. For the in situ experiment, neutron spectra and reaction rates for dosimetry reactions were calculated for several points inside the assembly. For the TOF experiment, angular neutron leakage spectra from the assembly were calculated. Results with TRIPOLI were comparable to those with MCNP in most calculations, but a difference between TRIPOLI and MCNP calculation results, probably caused by inadequate treatment of inelastic scattering data in TRIPOLI, appears in some calculations.

Sensitivity and uncertainty analyses of the HCLL mock-up experiment

Within the European Fusion Technology Programme dedicated computational methods, tools and data have been developed and validated for sensitivity and uncertainty analyses of fusion neutronics experiments. The present paper is devoted to this kind of analyses on the recent neutronics experiment on a mock-up of the Helium-Cooled Lithium Lead Test Blanket Module for ITER at the Frascati neutron generator. They comprise both probabilistic and deterministic methodologies for the assessment of uncertainties of nuclear responses due to nuclear data uncertainties and their sensitivities to the involved reaction cross-section data. We have used MCNP and MCSEN codes in the Monte Carlo approach and DORT and SUSD3D in the deterministic approach for transport and sensitivity calculations, respectively. In both cases JEFF-3.1 and FENDL-2.1 libraries for the transport data and mainly ENDF/B-VI.8 and SCALE6.0 libraries for the relevant covariance data have been used. With a few exceptions, the two different methodological approaches were shown to provide consistent results. A total nuclear data related uncertainty in the range of 1–2% (1σ confidence level) was assessed for the tritium production in the HCLL mock-up experiment.

International comparison of measuring techniques of tritium production for fusion neutronics experiments: Status and preliminary results

A neutronics experiment has been launched in the European fusion technology program on a mock-up of a test blanket module with the objective to validate the capability of nuclear data to predict nuclear responses with qualified uncertainties. In the experiment, the mock-up will be irradiated with a 14-MeV neutron source and the tritium production rate will be measured and compared with the calculated value by neutron cross sections from the European Fusion File. Given the difficulty of performing a reliable measurement of tritium production rate in such experiments, an international benchmark comparison on tritium measurement techniques has been carried out in collaboration between ENEA, TUD/VKTA and also JAERI that has already performed such experiments. The main purpose of the comparison is to establish the reference technique of TPR measurements to be used later in the TBM experiment. Three steps of the comparison procedure are presented in the paper as well as the preliminary results. The implications for the TBM experiment are also discussed.

Neutronics experiments for ITER at JAERI/FNS

A series of fusion neutronics experiments has been performed at the Fusion Neutronics Source facility at Japan Atomic Energy Research Institute as ITER EDA R&D tasks to find ways of dealing with various nuclear problems originating from 14 MeV neutrons in ITER. Recently three groups of experiments were carried out: (1) straight duct streaming experiments, (2) decay heat experiments, and (3) development of a fusion power monitor utilizing activation of water. The straight duct streaming experiments suggest that the calculation accuracy for straight duct streaming analyses in ITER nuclear designs is ±40%. The decay heat experiments show that the accuracy of the decay heat calculation is within 10% for copper and type 316 stainless steel, while it is ∼30% for tungsten. It is demonstrated that a fusion power monitor utilizing activation of water is applicable to ITER.

Neutronics Integral Experiments of Simulated Fusion Reactor Blanket with Various Beryllium Configurations Using Deuterium-Tritium Neutrons

Fusion neutronics experiments are performed on a full-coverage blanket with various configurations of a beryllium neutron multiplier. In the basic experimental system, a lithium carbonate enclosure contains a lithium oxide test zone and a deuterium-tritium neutron source to simulate a neutron spectrum in a fusion reactor. Five beryllium configurations are adopted to examine the effects of neutron multiplication and reflection by beryllium. The measurements are carried out along the central line in the test zone. Various measurement techniques are applied to obtain the tritium production rate distribution, which is one of the most important parameters for assessing the total tritium breeding ratio in a fusion blanket. In addition, the reaction rates and the neutron spectrum are measured to provide test data for confirmation of calculation results. These data are compared among six different configurations of the experimental system. Consistency between the different techniques for each measured parameter is also tested among different experimental systems. The experimental results are compared with the calculations by DOT 3.5 using JENDL-3/PRI and /PR2. The calculation differs from the experimental data by <10%, except for the beryllium zone.

Spectrum Weighting Function Method for In-Situ Fast Neutron and Gamma-Ray Response Measurements in Fusion Integral Experiments with an NE213 Scintillation Detector

Spectrum weighting function method with an NE213 scintillation detector has been applied to measurements of integral parameters such as tritium production rate from {sup 7}Li, in-system neutron integral flux and gamma-ray heating rate in fusion neutronics experiments. The NE213 scintillation detector can separate neutron and gamma-ray responses from each other, and those detector responses give energy information of both neutron and photon from recoil-proton and recoil-electron spectra, respectively. Connecting these energy responses with the energy responses of the nuclear parameters of interest such as {sup 7}Li(n,n{prime}{alpha}){sup 3}T reaction cross section, step function response of neutron energy and mass energy absorption coefficiency of gamma-ray, the corresponding nuclear parameters are obtained indirectly. The conversion method from the raw response of the detector is introduced by a spectrum weighting function.

Analysis of Induced Activities Measurements Related to Decay Heat in Phase IIC Experimental Assembly: USDOE/JAERI Collaborative Program on Fusion Neutronics Experiments

Analysis of Induced Activities Measurements Related to Decay Heat in Phase IIC Experimental Assembly: USDOE/JAERI Collaborative Program on Fusion Neutronics Experiments

Experimental Measurements and Analysis of Nuclear Heat Deposition Rates in Simulated D-T Neutron Environment: JAERI/USDOE Collaborative Program on Fusion Neutronics Experiments

The experimental measurement of nuclear heat deposition rates in a simulated D-T fusion neutron environment has assumed importance due to untested nature of large body of kerma factor libraries. An...

Experimental Techniques and Measurement Accuracies

A brief description of the experimental tools available for fusion neutronics experiments is given. Attention is paid to error estimates mainly for the measurement of tritium breeding ratio in simulated blankets using various techniques.