Time-resolved triton burn-up measurements have been performed using a new type of 14 MeV neutron detector based on scintillating fibres. The shot-integrated triton burn-up ratio was measured to be in the range 0.3-2.0%. Time histories of 14 MeV emission after NB turn-off have been analysed based on the classical slowing-down theory. Assuming the loss of fast tritons can be represented as a diffusivity, values increasing with increasing toroidal ripple were determined between 0.05 and 0.15 m 2 s −1 , from the modelling of the time histories of the 14 MeV emission after the NB turn-off.

Photoneutron cross sections were measured for 91Zr, 92Zr, and 94Zr near the neutron separation energy with quasimonochromatic gamma rays. The data exhibit some extra components around the neutron threshold. A coherent analysis of the photoneutron data for 92Zr together with the neutron capture on 91Zr based on the microscopic Hartree-Fock-Bogoliubov plus quasiparticle random-phase approximation model for the E1 strength has revealed the presence of an M1 resonance at 9 MeV. The microscopic approach systematically shows the same M1 strength in the photoneutron cross section for 91Zr and 94Zr. The total M1 strength is about 75% larger than the strength predicted by the systematics, being qualitatively consistent with the giant M1 resonance observed in the inelastic proton scattering.

In reversed magnetic sheaf-plasmas, fast ion confinement is anticipated to deteriorate because of a weak poloidal magnetic field in the core. In fact, in experiments at JT-6OU considerable depletion of triton burnup in reversed magnetic shear has been observed, compared with normal (positive) magnetic shear. The experimental triton burnup in the reversed shear was 11 to 39% of that expected, while that in the normal shear was 64 to 87%. Here, the expected burnup is based on one dimensional (1-D) calculations that assume classical slowing down and no diffusion of fast tritons. Orbit following Monte Carlo simulations, which treat finite orbit effects and ripple transport processes properly, match the experimental depletion and indicate that ripple loss is responsible for the enhanced triton loss in reversed shear operations. The results raise concerns about serious megaelectronvolt ion loss in reversed shear operations in steady state tokamak reactors

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To ensure the validity of their national standards, National Metrology Institutes (NMIs) participate regularly in international comparisons. In the area of neutron metrology, Section III of the Consultative Committee for Ionizing Radiation is in charge of the organization of these comparisons. From September 2011 to October 2012, the eleventh key comparison, named CCRI(III)-K11, took place at the AMANDE facility of the LNE-IRSN, in France. Participants from nine NMIs came with their own primary reference instruments, or instruments traceable to primary standards, with the aim of determining the neutron fluence, at 1 m distance from the target in vacuum, per monitor count at four monoenergetic neutron fields: 27 keV, 565 keV, 2.5 MeV and 17 MeV.The key comparison reference values (KCRV) were evaluated as the weighted mean values of the results provided by seven participants. The uncertainties of each KCRV are between 0.9% and 1.7%. The degree of equivalence (DoE), defined as the deviation of the result reported by the laboratories for each energy from the corresponding KCRV, and the associated expanded uncertainty are also reported and discussed.Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

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