Nuclear data for fusion applications

Abstract

Abstract. Achieving the economically viable release of energy by the fusion process has proved a major scientific and technological challenge. The nuclear reactions involved in the fusion process are well understood, but the interaction of the neutrons with the materials surrounding the plasma is an area of current research. The neutrons have energies larger than those experienced in fission and this has been a driver to extend the types and amounts of nuclear data. Designs for fusion devices require neutron and photon transport calculations to generate the spectra required to provide the nuclear responses. Such calculations require cross section data for all elements present in the device. ITER is the next step on the road to demonstrating the commercial generation of electricity. The importance of nuclear data for ITER was realized many years ago, which led to the release of FENDL-1 in 1995. This contained both general and special purpose files; an example of the latter is activation. Development of these files focused on completeness -including γ production and covariances; the files generally had an upper energy limit of 20 MeV. The types of data in the fusion relevant libraries are sufficient for all foreseeable fusion devices. However, the transition in fusion research from plasma physics towards technology requires an understanding of the materials damage caused by the intense fluxes of neutrons that will be found in power plants. To gain this knowledge a materials test facility, IFMIF, is required. This is planned to operate in parallel with ITER and will use accelerated beams of deuterons striking a flowing lithium target to generating an intense neutron field. The neutrons will mostly be fusion relevant, but there will be a high-energy tail extending up to ∼55 MeV. These high energy neutrons further extend the amount of nuclear data required and have stimulated much theoretical and experimental work covering the energy range >20 MeV. Examples of recent general purpose evaluations, new activation libraries and benchmarking are described and the challenges for nuclear data for fusion discussed.

Performance of the neutron time-of-flight facility n_TOF at CERN

“…At present there are several neutron ToF facilities in the world devoted to the measurement of neutron-induced reactions cross sections. These use different methods for neutron production and have flight path lengths ranging between less than one meter to 400 m. Among these, the most active in the recent years are (flight paths are given in parenthesis) the n TOF facility [11][12][13][14] (185 m) discussed further in this paper, GELINA at JRC-IRMM in Belgium [15] (10,30,50,60,100,200, 300 and 400 m), DANCE at LANSCE in the USA [16] (20 m) and AN-NRI at J-PARK in Japan [17] (22 and 28 m). In addition, two new facilities will soon become operational in Europe: n TOF-EAR2 at CERN in Switzerland [18] (20 m) and FRANZ in Germany [19] (0.8 m).…”

“…Nevertheless, the cross sections given in different evaluations are frequently incompatible and their accuracy is lower than needed. This makes it necessary to perform new and more accurate measurements of many isotopes and reactions, which are summarized for instance by the Nuclear Energy Agency in its High Priority Request List [9], but also in review papers on data needs for fusion [10] and astrophysics [1].…”

A Study on the Establishment of Radiation Dose Estimation Procedure for Accumulated Radioactive Ions for RAON ISOL System

“…The general procedure of FISPACT code is briefly reviewed in section 2.2.1. To estimate our case, a process was proposed in section 2.2.2 using modified FISPACT 2010 [3][4] code.…”

Prompt gamma-rays from fast neutron capture in nat-Ni

“…The γ-ray yield induced by interaction of fast neutrons with atomic nuclei of the reactor materials are of great importance for the reactor core calculations [1]. It is, for example, requested for the estimation of energy release, γ-ray shielding and radiation swelling of the reactor pressure vessel internals.…”