Horonobe Underground Research Laboratory project synthesis of phase I investigation 2001-2005 volume "Geological Disposal Research"

Fujita, Tomoo; Taniguchi, Naoki; Matsui, Hiroya; Tanai, Kenji; Nishimura, Mayuka; Kobayashi, Yasushi; Hiramoto, Masayuki; Maekawa, Keisuke; Sawada, Atsushi; Makino, Hitoshi; et al.

JAEA-Research 2007-045, 140 Pages, 2007/03

JAEA-Research-2007-045-1.pdf:38.33MB
JAEA-Research-2007-045-2.pdf:44.62MB

This report summarizes the progress of research and development on geological disposal during the surface-based investigation phase (2001-2005) in the Horonobe Underground Research Laboratory project (HOR), of which aims are to apply the design methods of geological disposal and mass transport analysis to actual geological environments and derive future subjects based on the results. The design methods of geological disposal were reviewed based on the recent knowledge and the advertences were identified. Then the parameters for virtual design of engineered barrier system, backfill deposition hole and tunnel were set up based on actual geological conditions obtained from the surface-based investigations in HOR as an example of actual geological environment. The conceptual structure from site investigation and evaluation to mass transport analysis was represented as a work flow at first. Then following this work flow a series of procedures for mass transport analysis were carried out based on actual geological conditions obtained from the surface-based investigations in HOR to illustrate the functioning of the work flow and the applicability of this methodology. Consequently, knowledge that will help follow-up or future execution and planning activities was obtained.

Study on Radiation Dose from Vitrified Waste

WAKASUGI, Keiichiro; Miyahara, Kaname; Makino, Hitoshi; Ishiguro, Katsuhiko; Sawamura, Hidenori*; Neyama, Atsushi*; Nishimura, Kazuya*

JNC TN8400 2003-022, 84 Pages, 2003/11

JNC-TN8400-2003-022.pdf:9.58MB

The radiation dose from the vitrified waste which is the same specification set in the Reference Case of the second progress report (H12 report) was evaluated quantitatively taking into account of the shield of the canister and the overpack. In order to understand the feature of radiation dose from the vitrified waste in terms of shielding, the thickness of the concrete shield to decrease less than safety standard for a radiation controlled zone was evaluated. Main results are summarized as follows. (1)The effective dose rates in the case considering the vitrified waste and the canister decrease approximate 45 orders of magnitude during the period of 1,000 years after vitrification due to decay of short half-life radionuclides. The effective dose rate doesn't decrease from 1,000 to 10,000 years. (2)The effective dose rates at the outside of overpack in the case considering the vitrified waste, canister and overpack are smaller than those inside of overpack approximate 5 orders of magnitude during the period of 100 years due to shielding effect of the overpack. However this difference is relatively small after 100 years since the contribution of radiation to total effective dose rates decrease due to decay of fission products. (3)Excepting a few cases, the result using the old law (dose equivalent rate) is larger than the result using the new law (effective dose rate). However the difference between these results is less than factor of 1.2. (4)The thickness of the concrete shield required to attenuate the effective dose during the period of 50 years less than safety standard for a radiation controlled zone is calculated as approximate 0.8m1.5m. The important factors to determine the thickness of the concrete shield are the radiation in the case of vitrified waste and the canister, and the neutron radiation in the case of vitrified waste, canister and overpack.

Polarized neutron scattering study of spin chirality in multiferroic material HoMnO under electric field

Kimura, Hiroyuki*; Wakimoto, Shuichi; Nishihata, Keisuke*; Noda, Yukio*; Kakurai, Kazuhisa; Kon, Keiichiro*

no journal, , 

Multiferroic materials are known to show gigantic magnetoelectric effects. One of the microscopic models for polarization in such systems is based on spin chirality. We have perfoermed polarized neutron scattering experiments using HoMnO single crystal to study correlation between the spin chirality and ferroelectric polarization. We found that the spin chirality is absent in the high temperature paraelectric HT-ICM phase whereas it appears in the ferroelectric LT-ICM phase. This fact demonstrates a strong coupling between the spin chirality and the ferroelctric polarization.

SR measurement of single-crystalline SmS

Ito, Takashi; Higemoto, Wataru; Suzuki, Hiroyuki*; Imura, Keiichiro*; Sato, Noriaki*

no journal, , 

no abstracts in English