3Research and Development on Geological Disposal of High-Level Radioactive Waste

R&D Supporting the Technology and Reliability of Geological Disposal in Japan
Overpack(e.g. carbon steel)

Stable Geological
Environment(Natural Barrier)(greater than 300 m
below surface)

BufferMaterial(e.g. bentonite)

Fig.3-1 Basic concept of geological disposal of high-level
radioactive waste in Japanin earnest (Topics 3-1, 3-2, 3-3, 3-4). Underground tunnels
serve as a place for the public to experience deep geologicalenvironments first-hand and appreciate our R&D activities. In
addition, studies on tectonics, volcanic and faulting activities,
and so on have been underway for evaluating the long-term
stability of geological environments in Japan (Topic 3-5).
In parallel with this geoscientific research, we are conducting
an extensive study for performance assessment of multibarriersystems, engineered barrier systems, and long-term chemicaland migration behavior of radionuclides at Tokai to improvegeological disposal technology (Topics 3-6, 3-7, 3-8).
These studies involve the use of geological environment dataobtained at both URLs. A prototype knowledge management
system that was developed in 2009 has been improved tosystematically provide multiple lines of evidence and R&Dresults. In 2012, the Information Synthesis and Interpretation
System (ISIS), which supports the implementer in planning,performing, and evaluating the preliminary investigation,
was developed by integrating each expert system, using theexperience and know-how that experts have garnered throughR&D activities.
Horonobe UndergroundResearch Center(Horonobe, Hokkaido)

Tono Geoscience Center(Toki & Mizunami, Gifu)● Horonobe URL*(Sedimentary Rock )Cooperation andCollaboration● Mizunami URL*(Crystalline Rock)

Other Organizations

VitrifiedWaste

JAEA Knowledge
Management System

Knowledge Base
Concept image

Tokai R&D Center(Tokai, Ibaraki)

・Data・Documents
・Software・Experience and Expertise・Simulations
・Evidence・Expert Systems● Engineering Scale Test & Research Facility (ENTRY)● Quantitative Assessment Radionuclide

Concept image

Migration Experimental Facility (QUALITY)

ENTRY*URL: UndergroundResearch Laboratory

Fig.3-2 Japan Atomic Energy Agency’s R&D activities

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JAEA R&D Review 2013

Engineered Barrier System

Geological disposal is one of the options for isolating highlevel radioactive waste (HLW) produced during nuclear power
generation from human environments over a long period oftime. This is an issue that remains critical in spite of the revisionof the national nuclear energy policy and one that must now be
dealt with by the present generation. In Japan, spent fuel frompower reactors is reprocessed to extract reusable uranium andplutonium for power generation purposes. The liquids separated
from the spent fuel during chemical reprocessing are solidified
into a stable glass form. According to the Japanese concept,
vitrified wastes are encapsulated in a thick steel overpack,which is surrounded by highly compacted bentonite and placedin a stable geological environment below 300 m (Fig.3-1).
Geological disposal of HLW will be a long-term project lasting
more than 100 years. The project begins with site selection,
continues to repository construction and operation, which
will be followed by post-closure monitoring. It is thus very
important to proceed with the project efficiently, as a nationalresponsibility, by continuously reinforcing the technical baseand, more importantly, building public confidence. To this end,
we have made and continue to make steady progress in researchand development (R&D) in various fields, such as geoscientificresearch, engineering technology, and safety assessment, toimprove the technology used for and reliability of geologicaldisposal in Japan. Our efforts are also focused on promoting
public understanding through the dissemination of relevant
information and on opening our R&D facilities to the public.
A particular focus of our current R&D is on projects at two
underground research laboratories (URLs)—one at Mizunami
for research on crystalline rocks and the other at Horonobe forresearch on sedimentary formations (Fig.3-2)—with the main
aim of developing a sound technical basis for the formulationand implementation of safety regulations. In March 2013,
shaft excavation reached a depth of 500 m at Mizunami and350 m at Horonobe, and some research galleries were madeavailable for use. Multidisciplinary investigations are ongoing,as the reliability of a variety of investigative techniques shouldbe tested and confirmed before site characterization begins

QUALITY

ImplementerRegulator

Public Understanding
and Confidence