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Owada, Hitoshi*; Mihara, Morihiro; Iriya, Keishiro*; *
JNC TN8400 99-057, 43 Pages, 2000/03
Cementitious materials are considered as candidate materials for the geological disposal of high-level radioactive waste and TRU waste. As the pH and the Ca content of leachate from the cementitious materials are high, the host rock and the buffer-material would be degraded by the leachate in the long-term. Therefore, transport properties and parameters such as solubilities and distribution coefficients of radionuclides would be changed and affect the performance of the repository. In order to dissolve this "High pH plobrem", the use of a low alkalinity cement is considered for the disposal. In this study, we summarized the necessity of the low alkalinity cement, and developed the approach of the low alkalinization of cement. And, the following were carried out in this study : A leaching test of cement paste, a fluid test of the mortar and a installation test of the concrete to the trial structure. From the leaching test using the cement paste, we confirmed that we were able to obtain the low alkalinity cement (HFSC) by addition of pozzolanic materials such as silica-fume and flyash. From the result of the fluid test of the mortar, we chose the cement for the practicability evaluation. The practicability of low alkalinity concrete was evaluated by installation test to the trial structure.As a result of these examinations, we proved that the pH value of the leachate from the cementitious material was reduced by adding SF and FA to Portland cement. Simultaneously, SF and FA had to be added in order to obtain the good workability. In addition, workability and mechanical strength of the cement which SF and FA were added are almost equivalent to the ordinary Portland cement. The results shows that the HFSC has high practicability.
Bottcher, J. T.
PNC TN9440 97-011, 215 Pages, 1997/06
J.H.Bottcher started his intemational Fellow position at PNC on March 25, 1996.During his 15 months in PNC he worked in the Irradiation Section of the Experimental Reactor Division. There he worked on conceptual design reviews and related the US irradiations methodology to the members. His work extended to other Divisions at OEC and Tokai Works, mainly related to fuel development and irradiation performance. In these efforts he published two papers, wrote a desip review document, and presented six lectures on irradiated fuels and materials. In addition he participated in coordinating a new four year PNC/DOE collaborative program on irradiated steels characterization.
