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JAEA Reports

Clearance of concrete generated from modification activities of JRR-3; Results for measuring and evaluating radioactivity concentration

Ogoshi, Yurie; Satoyama, Tomonori; Kishimoto, Katsumi; Nanri, Tomohiro; Suzuki, Takeshi; Tomioka, Osamu; Takaizumi, Hirohide*; Kanno, Tomoyuki*; Maruyama, Tatsuya*

JAEA-Technology 2017-017, 152 Pages, 2017/08

JAEA-Technology-2017-017.pdf:15.97MB

At Nuclear Science Research Institute, clearance works for about 4,000 tons of extremely low-level radioactive concrete debris, which were generated from the modification activities of JRR-3 from FY 1985 to FY 1989 and stored in the waste storage facility NL, carried out. First of this clearance works, method for measuring and evaluating radioactivity concentration was approved by Minister of MEXT on July 25, 2008. And then, clearance works were started from FY 2009. Measuring and evaluating radioactivity concentration was achieved by using the approved method, and was confirmed by government. And then, clearance works were completed in FY 2014. The clearance concrete was recycled as a material for restoration works of the 2011 off the Pacific coast of Tohoku Earthquake. This report summarizes the results of measuring and evaluating radioactivity concentration, achievement of confirmation by government, recycling of cleared concrete and cost for clearance works.

Oral presentation

Synthesis and properties of novel cesium containing Lanthanide-organic framework

Nankawa, Takuya; Ogoshi, Yurie; Watanabe, Masayuki

no journal, , 

Removal of cesium by porous materials from various environments has recently attracted much attention because of the Fukushima crisis. The behavior of cesium in the presence of porous materials, such as Cs uptake selectivity and permeability, may depend on the sizes of porous materials but the relationship is not revealed yet because controlling the pore sizes were difficult. On the other hand, Metal-organic framework (MOF) materials that have highly-ordered pore and the pores sizes of which can be controlled by selecting appropriate ligands and metals have been investigated in these two decades. We synthesized novel lanthanide-organic framework containing cesium ions with the formula of LnCs(ox)$$_{2}$$ (Ln = La, Eu, Tb, Er, Yb, Lu), the pore sizes of which can be precisely controlled by changing lanthanide ions, to investigate the relationship between Cs permeability and pore sizes.

Oral presentation

Synthesis, structure, and cesium uptake properties of novel rare earth organic frameworks

Nankawa, Takuya; Ogoshi, Yurie

no journal, , 

Removal of cesium by porous materials from various environments has recently attracted much attention because of the Fukushima crisis. Among the porous materials, Prussian-blue has so high Cs selectivity that they can be used even in the sea water. But because they had a possibility to generate HCN gas by the radioactive decomposition, they were not used in Fukushima. We synthesized novel rare earth organic framework with the formula of Re(NH$$_{4}$$)(C$$_{2}$$O$$_{4}$$)$$_{2}$$(H$$_{2}$$O) (Re = Y, Eu, Tb, Dy, Ho, Er) by modifying the pores of Prussian blue. We used single crystal X-ray diffraction analysis to determine the molecular structures of Tb(NH$$_{4}$$)(C$$_{2}$$O$$_{4}$$)$$_{2}$$(H$$_{2}$$O). The diameter of the pore around NH4 is about the same size with the pores of Prussian blue. And it was revealed that the structures of MOFs are isostructural and their pore sizes of are precisely controlled by changing lanthanide ions. We demonstrated Cs uptake experiment in water solution and revealed that Cs was uptaken by the MOFs.

Oral presentation

Separation and recovery of radioactive cesium and strontium by metal-organic-frameworks

Nankawa, Takuya; Ogoshi, Yurie; Kuwahara, Akira; Yamada, Teppei*; Zanella, M.*; Jansat, S.*; Manning, T.*; Rosseinsky, M.*

no journal, , 

Radioactive Cesium(Cs) and Strontium(Sr) in liquid waste can be separated by porous materials such as zeolite. The pore sizes of these materials seems to identify metal ion radius or hydrated ion radius of Cs or Sr. But since it is very difficult to change the pore sizes of these materials, we cannot investigate the relationship between the pore sizes and Cs or Sr uptake behavior of these materials. And since the frameworks of these materials are rigid, it is very hard to recover Cs or Sr absorbed in the materials and we have to dispose Cs or Sr containing material as nuclear waste. But if Cs and Sr can be recovered from the materials, we can make use of these radioactive nuclides as radiation or heat source. On the other hand, metal-organic-frameworks (MOF) have attracted much interest in this two decades because of its fascinating characters such as gas absorption, catalytic or optical properties. The advantages of MOF over zeolites or other porous materials are a highly-ordered structure composed of metal ions and organic ligands, and highly controllable pore sizes that can be controlled by the length of ligand and ionic radii of metal ions. Moreover, structures of MOF can easily be influenced by solution phase. So, it becomes easy to recover guest ions from MOF. In this study, we synthesized a novel series of MOF, (NH$$_{4}$$)[Ln(C$$_{2}$$O$$_{4}$$)$$_{2}$$(H$$_{2}$$O)]. The structure is shown in Fig.1. All the structures the MOF are isostructural. The cell lengths and pore sizes tend to be decreased with the increase of atomic number in response to the decrease of ionic radius known as lanthanide contraction. And we investigated the behavior of Cs or Sr uptake by changing lanthanide ions in the MOF. Moreover, we found that Cs can be recovered from the MOF and we can reuse the MOF again. According to these results, we found a new material to recover Cs from radioactive liquid waste to decrease the amount of waste and make use of Cs as radiation source.

Oral presentation

Separation and recovery of radioactive ions by metal-organic-frameworks

Nankawa, Takuya; Yamada, Teppei*; Ogoshi, Yurie; Kuwahara, Akira; Alexandros, K.*; David, S.*; Marco, Z.*; Jansat, S.*; Troy, D. M.*; Matthew, J. R.*

no journal, , 

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