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Sorption Behavior of Radionuclides on Calcium-Leached Mortar

Published online by Cambridge University Press:  21 March 2011

Nobuo Ashikawa ,
Takatoshi Tajima ,
Hiroshi Saito  and
Ai Fujiwara
Nobuo Ashikawa
Affiliation:
Kyushu Environmental Evaluation Association, 1-10-1 Matsukadai, Fukuoka 813-0004, Japan
Takatoshi Tajima
Affiliation:
Obayashi Corporation, 640 Shimokiyoto 4-chome, Kiyose-shi Tokyo 204-8558, Japan
Hiroshi Saito
Affiliation:
Obayashi Corporation, 640 Shimokiyoto 4-chome, Kiyose-shi Tokyo 204-8558, Japan
Ai Fujiwara
Affiliation:
Radioactive Waste Management Center, No.15 Mori Bldg. 2-8-10 Toranomon, Minato-ku Tokyo 105-0001, Japan
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Abstract

Low-level radioactive waste (LLRW) is disposed of by shallow land burial. Reinforced concrete is used as the radioactive waste repository. However, the concrete structure is in contact with water and will gradually degrade over an extended period of time due to leaching.

It is important to investigate the interaction between radionuclides and degraded concrete in the safety assessment of nuclear waste disposal. The authors measured the distribution coefficients (Kd) of various radionuclides for calcium-leached mortars. The calcium-leached mortars were prepared by an accelerated leaching test for mortar based on the electrical potential gradient. These degraded conditions are similar to that of degraded concrete in contact with water for a long period of time. The degradation degree of calcium-leached mortar is evaluated by the CaO/SiO2 molarratio (Ca/Si ratio) of calcium silicate hydrate (C-S-H).

As a result, the relationship between Kd and the Ca/Si ratio in C-S-H can be roughly grouped into the following three types:

1.137Cs and 85Sr – Kd decreases with an increase in the Ca/Si ratio.

2. 95mTc and 110mAg – There is no correlation between Kd and the Ca/Si ratio.

3. 14C, 241Am and 125I – Kd increases with an increase in the Ca/Si ratio.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 663: Symposium – Scientific Basis for Nuclear Waste management XXIV , 2000 , 97
Copyright
Copyright © Materials Research Society 2001

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References

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