[en] Validity of the Ssub(n) approximation which is used for neutronics calculation of the fusion reactor blankets is confirmed by comparing the calculated tritium breeding ratio in the benchmark model with the recommended one. Effects of the following on accuracy of the calculated tritium breeding ratio were studied: The number of energy groups, the number of directional mesh points in the Ssub(n) approximation, anisotropy of neutron scattering, and selection of the spatial mesh number. (auth.)

[en] For the formal evauation of the JENDL series nuclear data files in fusion neutronics field, ''Subworking Group on Fusion Neutronics Integral Test'' was formed among the member of both the Subcommittee on Reactor Constants on the Japanese Nuclear Data Committee and the Subcommittee on Fusion Reactor of the Research Committee on Reactor Physics. The integral test was planned on the basis of results of an enquete. The results of integral tests were reported by seven groups at 24th meeting of Subcommittee on Fusion Reactor held on Oct. 30, 1987. This report is based on the presentations and discussions at the 24th meeting and made comments on the nuclear data of ¹H, ⁶Li, ⁷Li, ⁹Be, ¹²C, ¹⁶O, Si, Cr, Fe, Mn, Cu and Pb. (author)

No abstract available

No abstract available

[en] An experimental method of neutron angular spectrum measurement in a slab geometry with D-T neutrons has been developed and its characteristics were examined. This method separates collided flux from uncollided flux. A neutron collimator restricts the measuring area on the surface of a slab assembly and the detector-collimator response function was determined. The time-of-flight method with two discrimination levels was adopted using an NE213 scintillation detector with pulse shape discrimination to obtain an accurate efficiency. Such measurements provide useful information in fusion blanket research. The results of the spectrum measurement were compared with calculated neutron spectra. The estimated overall error of the spectrum was within 5%. (orig.)

[en] As the first blanket experiment using the Fusion Neutronics Source (FNS), the integral experiment on a Li₂O-C assembly was carried out. Measured items were as follows: 1) absolute fission-rate distributions, 2) tritium production-rate distributions, 3) response distributions of LiF TLD's, 4) induced activity of SUS316 stainless steel. The measured values were compared with calculated ones. (author)

[en] Two types of clean benchmark experiments have been carried out at the FNS (Fusion Neutronics Source) facility. They are integral experiments and time-of-flight experiments. The former includes integral experiments on cylindrical assemblies with: (1) 60-cm thick lithium oxide (Li₂O), (2) 60-cm thick graphite, and (3) 40-cm thick Li₂O followed by 20-cm thick graphite. Various reaction rates such as tritium production rate and neutron spectra were measured in these experiments. The time-of-flight experiments were conducted to measure angle-dependent neutron spectra leaking from: (1) Li₂O, (2) graphite, and (3) lithium-metal slab assemblies. These experiments were numerically analyzed by making use of the DOT3.5 transport code with newly processed 125-group cross-section sets, i.e., JENDL-3PR1, JENDL-3PR2, ENDF/B-IV, and ENDF/B-V (¹²C only). It was found that the calculations based on JENDL-3PR1 and JENDL-3PR2 predicted tritium production rates of ⁶Li and ⁷Li better than those based on ENDF/B-IV. These analytical results are expected to provide useful information for the future development of the JENDL-3 nuclear data file. (author)

[en] This issue is the collection of the papers presented at the title meeting. The 22 of the presented papers are indexed individually. (J.P.N.)

[en] A fast neutron source system (FNS) has been constructed at the Tokai Laboratory of Japan Atomic Energy Research Institute. The pulse width of d-d neutron from the FNS is 1.72 ns. The length of flight path is about 33 m. Prepared detectors are a NE-213 bank, a (B-10)₄C-NaI bank, and Li-6, Li-7 glass scintillators. Various electronic circuits are provided. A DEC VAX- 11/780 computer is used for the data processing. The experiment to measure the angle-dependent leak spectra by Li₂O and Li plate assemblies are designed and will be done in near future. (Kato, T.)

[en] The measurement of neutrons by self dosing method using a TLD is the same in principle as the measurement with an activated foil. It cleverly utilizes the property of a TLD, and measures the activated dose by using the TLD itself. Since the annealing of a TLD completely eliminates the TL generated by radiation including neutrons, neutron flux can be measured by making another TL generated by the self dosing of a certain nuclide for the appropriate time. The conditions under which the self dosing method is established are as follows. (1) The objective nuclide is contained as a component of a TLD, and its activation cross section is appropriately large. (2) The half life of the nuclide is comparatively larger or smaller than that of coexisting nuclides. (3) The self dosing radiation is β (α)-decay. As the examples of thermal neutron dose measurement, the TLD's of CaSO₄; Dy, CaF₂; Dy and CaF₂; natural were fabricated into the ampoules of each about 20 mg, and irradiated in a swimming-pool reactor. The dynamic range may be extended by using ⁴⁵Ca or ¹⁶⁵Dy properly. As the examples for fast neutron dose measurement, LiF and Mg₂SiO₄; Tb TLD's were used. The lower limit of detection is about 2 x 10⁸ n/cm² for 14 MeV neutrons. The TLD self dosing method may be used for the measurement of tritium production rate in the blanket of a D-T fusion reactor. Though its efficiency is low at present, its measurement will be achieved by taking the irradiation time and self dosing time long and increasing neutron source intensity. (Wakatsuki, Y.)