ASME Message

Abstracts
In the current concept of repository for radioactive waste disposal, compacted bentonite will be used as an
engineered barrier mainly for inhibiting migration of radioactive nuclides. Hydrogen gas can be generated inside of the
engineered barrier by anaerobic corrosion of metals used for containers, etc. It is expected to be not easy for gas to
entering into the bentonite as a discrete gaseous phase because the pore of compacted bentonite is so minute. Therefore it
is necessary to investigate the effect of gas pressure generation and gas migration on the engineered barrier, peripheral
facilities and ground. In this study, a method for simulating gas migration through the compacted bentonite is proposed.
The proposed method can analyze coupled hydrological-mechanical processes using the model of two-phase flow
through deformable porous media. Validity of the proposed analytical method is examined by comparing gas migration
test results with the calculated results, which revealed that the proposed method can simulate gas migration behavior
through compacted bentonite with accuracy.
4) 40020 – Planning of Large-scale In-situ Gas Generation Experiment in Korean Radioactive Waste Repository
Juyoul Kim, Sukhoon Kim, FNC Technology Co.(Korea Rep.);
Jinbeak Park, Sungjoung Lee, KRMC (Korea Rep.)
In the Korean LILW (Low- and Intermediate-Level radioactive Waste) repository at the Gyeongju site, the
degradation of organic wastes and the corrosion of metallic wastes and steel containers would be important processes that
a?ect repository geochemistry, speciation and transport of radionuclides during the lifetime of a radioactive waste
disposal facility.
Gas is generated in association with these processes and has the potential to pressurize the repository, which can
promote the transport of groundwater and gas, and consequently radionuclide transport. Microbial activity plays an
important role in organic degradation, corrosion and gas generation through the mediation of reduction–oxidation
reactions.
The Korean research project on gas generation will be performed by Korea Radioactive Waste Management
Corporation (KRMC). A large-scale in-situ experiment will form a central part of the project, where gas generation in
real radioactive low-level maintenance waste from nuclear power plants will be studied.
In order to examine gas generation from an LILW repository which is being constructed at present by 2012, two
large-scale facilities for the gas generation experiment (GGE) will be established, each equipped with a concrete
container for 16 or 9 drums of LILW from Korean nuclear power plants. Each container will be enclosed within a
gas-tight and acid-proof steel tank. The experiment facility will be filled with ground water that provides representative
chemical conditions and microbial inoculation in the repository near field.
In the experiment, the design includes long-term monitoring for the rate and composition of gas generated, and
aqueous geochemistry and microbe populations present at various locations through on-line analyzers and manual
sampling.
A main schedule for establishing the experiment facility is as follows: Completion of the detailed design until the
second quarter of the year 2010; Completion of the manufacture and on-site installation until the second quarter of the
year 2011; Start of the operation and monitoring from the third quarter of the year 2011.
5) 40024 – Estimation and measurement of porosity change in cement paste
Eunyong Lee, Haeryojng Jung, Ki-jung Kwon, KRMC (Korea Rep.);
Do-Gyeum Kim, Korea Institute of Construction Technology (Korea Rep.)
Laboratory-scale experiments were performed to understand the porosity change of cement pastes. The cement
pastes were prepared using commercially available Type-I ordinary Portland cement (OPC). As the cement pastes were
exposed in water, the porosity of the cement pastes sharply increased; however, the slow decrease of porosity was
observed as the dissolution period was extended more than 50 days. As expected, the dissolution reaction was
significantly influenced by w/c raito and the ionic strength of solution. A thermodynamic model was applied to simulate
the porosity change of the cement pastes. It was highly influenced by the depth of the cement pastes. There was porosity
increase on the surface of the cement pastes due to dissolution of hydration products, such as portlandite, ettringite, and
CSH. However, the decrease of porosity was estimated inside the cement pastes due to the precipitation of cement
minerals.
6) 40082 – Separation and Recovery of Sodium Nitrate from Low-level Radioactive Liquid Waste by
Electrodialysis
Yoshihiro Meguro, A Kato, Y Watanabe, Kuniaki Takahashi, JAEA (Japan)
Low-level radioactive liquid wastes including TRU elements have been generated from several treatments in
reprocessing facilities. These wastes usually include highly concentrated sodium nitrate. In Japan the liquid wastes are
planned to dispose in geological layer with HLW following solidification of them and in this plan it is considered that
leached nitrate from the solidified materials and its decomposition products would change sorption coefficients of
radionuclides and then their migration in the long-term would be influenced. Therefore a method to remove the nitrate
ions prior to the solidification is required. The authors have been developed a separation and recovery method of sodium
nitrate from the low-level radioactive liquid waste by using an electrodialysis method not only to remove the nitrate but
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