| Title | Investigation of radiocesium volatilization from soil by in-situ ground heating |
| Alternative title | 土壌の原位置加熱による放射性セシウムの除去可能性の検討 |
| Publisher | JAEA |
| Author | Department of Partnership Operations for Environmental Remediation, Headquarters of Fukushima Partne |
| Author | Nigyo-Toge Environmental Engineering Center |
| Author | Vitrification Technology Development Department, Tokai Reprocessing Technology Development Center |
| Author | Environmental Protection Section, Radiation Protection Department |
| Issued date | 2011-11 |
| Language | jpn |
| Page | 1p.-74p. |
| Type | report |
| Description | 福島第一原子力発電所の事故に伴い放射性核種によって広範囲の土壌が汚染され、さまざまな環境修復策が検討されている。セシウム(Cs)の揮発性を利用した原位置土壌加熱によるCs除去方法の有効性を確認するため、バーナーを用いた土壌加熱による土壌温度の上昇確認,加熱時の放射性Csの揮発挙動を調べた。草焼バーナーで土壌表面をCs化合物の融点まで加熱するには15分以上の加熱が必要であり、最大温度は700circCであった。また、土壌表面が約600circCまで加熱されても表面から1cmの深さでは約300circCまでしか上昇せず、5cmの深さでは50sim60circC程度であった。600circCsim1300circC及び5分sim60分とした加熱試験の結果、Cs-134並びにCs-137の加熱前後の放射能量変化率は-9.8%sim+14.0%の範囲でばらついている程度であり、顕著な揮発挙動は見られなかった。放射性Csの化学形態と揮発挙動を検討するため、Cs2CO3試薬を土壌又は模擬土壌のモルデナイト型ゼオライトと混合させたものについて、TG/DTA分析等を実施した。結論として、放射性CsがCs2CO3単体で存在した場合、加熱によって揮発除去できるが、SiO2とAl2O3が共存した場合、加熱によってCsAlSiO4等の化合物が生成され、放射性Csは土壌中に留まると推定される。 |
| Description | After the Fukushima nuclear accident, extensive area was contaminated with radionuclides from the Fukushima Daiichi Nuclear Power Plant and various methods have been investigated to remedy such contamination. To understand potential of in-situ ground heating and radionuclide desorption, behaviors of ground temperature and of radiocesium volatility by in-situ heating was investigated. More than 15 minutes was necessary to accomplish melting temperature of several cesium compounds by heating using portable burner and maximum temperature was about 700 degree in Celsius. At the time ground surface temperature was about 600 degree, the temperature at 1cm depth was about 300 degree, whereas the temperature at 5cm depth was 50-60 degree. Under the condition of heating temperature of 600-1,300 degree and heating period of 5-60 minutes, activity of Cs-134 and Cs-137 varied in the range of -9.8 to +14.0% after heating using electric furnace and any volatility of radiocesium was not recognized. TG/DTA analysis for soil and zeolite (mordenite) which mixed with nonradioactive Cs compound each were also carried out to understand chemical form and volatility behavior of radiocesium. It is suggested that chemical compound e.g., CsAlSiO4 would be formed when SiO2 and Al2O33 were composed in the system and radiocesium would remain in soil under the high temperature condition, whereas Cs in CsCO3 would be volatized in the SiO2 and/or Al2O3 free system. |
| Description | 著者所属: 日本原子力研究開発機構(JAEA) |
| Information source |  JOPSS Relation URLRelation URL |
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| URI | https://f-archive.jaea.go.jp/dspace/handle/faa/211524 |
