The 14 MeV Frascati neutron generator
Abstract
The 14-MeV Frascati neutron generator (FNG) uses the T(d, n)α fusion reaction to produce 5.0 × 1011 n/s. In FNG a beam of deuterons is accelerated up to 300 keV by means of a linear electrostatic tube and directed onto a tritiated-titanium target containing 37 × 1010 Bq of tritium. This paper describes the FNG facility and its auxiliary apparatus as well as the neutron source calibration performed using the associated α-particle method.
References (7)
- P. Batistoni
- T.S. Green
Rep. Prog. Phys.
(1974) - J.R. Pierce
J. Appl. Phys.
(1940)
Cited by (140)
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FENDL: A library for fusion research and applications
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The results of the validation using computational benchmarks showed generally good agreement among the tested neutron cross section libraries for neutron flux, nuclear heating, and primary displacement damage (dpa). Gas production (H/He) in structural materials showed substantial differences to the reference FENDL-2.1 library. The results of the experimental validation showed that the performance of FENDL-3.2b is at least as good and in most cases better than FENDL-2.1.
Future work will consider improved evaluations developed by the International Nuclear Data Evaluation Network (INDEN) for materials such as O, Cu, W, Li, B, and F. Additionally, work will need to be done to investigate differences in gas production in structural materials. Covariance matrices will need to be developed or updated as availability of consistent and comprehensive uncertainty information will be needed as fusion technology and facility construction matures. Finally, additional validation work for high energy neutrons, protons and deuterons, as well as validation work for the activation library will be needed.
Partially depleted operation of 250 μm-thick silicon carbide neutron detectors
2024, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentFusion experiments put many challenges on the neutron detection methods, since they require fast neutron counters and spectrometers with good energy resolution capable of operating in harsh environments under a large range of neutron flux intensities. Recently, SiC detectors were proposed for these roles due to their outstanding properties. Among those, the operation of SiC with partial polarization is of interest since it might allow for a fast neutron detector with efficiency tunable online, which would allow a good functionality under a large range of flux intensities.
This paper describes the characterization of a series of SiC detectors operated with a fraction of the polarization needed to achieve full depletion. The characterization is performed through I/V measurements, alpha irradiation in vacuum and neutron irradiation. A functionality with excellent detection characteristics is demonstrated, reaching an energy resolution of 1.05 % for 5.5 MeV alphas and 2.05 % for 14 MeV neutrons. Some limitations on the maximum bias will be also discussed, pointing out some challenges for the manufacturing of thick SiCs in the future.
Development and validation in water of FLUNED, an open-source tool for fluid activation calculations
2023, Computer Physics CommunicationsIn nuclear fusion installations, high-energy plasma neutron activates the cooling and breeding fluids, generating a mobile and distributed source of radiation. In water-cooled fusion reactors, such as ITER and DEMO, the most concerning radioisotopes present in the coolant are the 16N and 17N. Their prompt emission impacts the design, safety, and, ultimately, the economics of the plant as it can be the dominant source of radiation in regions far from the plasma. The flowing condition makes the calculation of radioisotope concentrations within an irradiated cooling circuit particularly challenging as it requires the coupling of the neutronics and fluid dynamics characteristics of the problem. Recent works showed that, except for simple and limited cases, the coupling requires the implementation of Computational Fluid Dynamics (CFD) methods. Nevertheless, the use of ad-hoc methodologies or the application of proprietary codes has hampered the participation and formation of common benchmarks among the neutronics community. In this work, we present the development of an open-source tool called FLUNED that studies the evolution of the concentration of radioactive species inside a fluid and that considers the fluid dynamics of the carrier. The tool is based on the open-source CFD code OpenFOAM and makes use of its modular nature to complement the fluid continuity equation with the radioisotope decay and production terms. In the second part of this work, we show the code validation using experimental data from the water activation experiment performed at FNG in Frascati in December 2019. The validation was performed by producing a computational chain that simulated the main components of the water circuit and estimated the counts in the two experimental detectors caused by the decay of the 16N and 17N isotopes. Finally, the positive comparison between the calculated and the experimental values allowed us to establish the validation of FLUNED for studies of fluid activation in water-cooled fusion experiments and reactors.
Design optimization of the closed-water activation loop at the JSI irradiation facility
2023, Fusion Engineering and DesignA closed-water activation loop is being built at the research reactor TRIGA at the Jožef Stefan Institute, Slovenia, which will serve as a well-defined and stable high energy gamma-ray and neutron source. The main focus of this work is to analyse and optimise the main components of the water activation loop to achieve the highest activity at reasonably low pressure drop. Both neutronic and hydraulic aspects were considered. The results show that the desired configuration consists of a high effective water volume of the inner activation part, outer observation part and narrow transport pipes connecting both parts. The complex snail-shape design of the inner part systematically outperformed other simplified designs by more than a factor of two for the main water activated isotopes (16N, 17N and 19O). The activity values increase strongly with increasing flow rate, but reach saturation at about 0.5 l/s. On this basis, the snail configuration was selected as the main candidate for both the inner activation and outer observation part. To not exceed the pressure drop of 3 bar within the closed-water loop, the nominal water flow rate and the inner diameter of the transport pipes were set to 0.5 l/s and 1.2 cm, respectively.
Application of an algebraic methodology for the combination of Berthold LB6411 and WENDI-II for neutron area monitoring in D-T neutron generators and fusion facilities
2022, Applied Radiation and IsotopesNeutron area monitors do not often have a good adjustment of their dose response functions to the ICRP74 neutron fluence-to-H*(10) conversion function between 10 and 20 MeV. The objective of this work is to establish a methodology to combine the dose response functions of Berthold LB6411 and WENDI-II, adjusting this combined function to the ICRP74 conversion function: this combination shows an almost perfect adjustment between 0.5 and 20 MeV. Thus, this article presents an easy and cheap alternative to the recalibration in D-T generators.