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[en] Distributions of radioactivities and dose rates inside nuclear facilities are estimated using a simulation code as well as radiation measurements. Concentrations of trace elements in aggregates are different more than those of major elements among the aggregates collected from different location. Hence, actual analyzed data of the relevant elements in aggregates give more accurate estimation on the activation. The analysis using an x-ray fluorescence (XRF) is not recommended for the trace elements but for the major elements. An activation analysis is suitable for the trace elements but not for the major elements. An instrumental analysis accompanied by sample digestion requires specific procedures for elements analyzed; but it can be used for most of elements. According to the geochemical standard data, the discrepancy of analytical values determined with different methods is negligible small when a suitable procedure is selected; most of elements can be determined with approximately 5% for an uncertainty. (author)
Journal
Shimizu Kensetsu Kenkyu Hokoku; ISSN 0289-8330; 
; (no.93); p. 5-10
; (no.93); p. 5-10
[en] A thermal treatment will be applied to reduce amount of high-level radioactive waste contaminated by radio-cesium from the Fukushima nuclear power plant accident. A chlorination vaporization process allows us to decrease the radiation level in the waste. Elements of the chloride produced by chemical reactions are vaporized in the process. We investigated the vaporization rates of various elements from ash samples treated with CaCl2 as an additive. In addition, we investigated the vaporization rates of the Cs and its processes of chemical reactions by interacting with CaCl2, MgCl2, or mixture of CaCl2 and CaO. (author)
[ja]
福島原発事故により発生した放射性セシウムを含む莫大な量の廃棄物の中で、放射能レベルの高いものには何らかの熱処理が適用され、生石灰等を用いた実証事業等が行われている。塩化揮発法は、化学反応を用いて塩化物になった目的元素を揮発させることにより濃度低減する手法である。本研究では、小型の炉を用いて、石炭灰に塩化揮発法を適用し、添加剤にCaCl2 を用いたときの様々な元素の揮発率を測定した。また、添加剤としてCaCl2、MgCl2、CaCl2 とCaOの混合物を用いたときの、Cs 揮発率とCs が揮発するまでの化学反応過程を明らかにした。(著者)Journal
Shimizu Kensetsu Kenkyu Hokoku; ISSN 0289-8330; ; (no.95); p. 145-152
; (no.95); p. 145-152
[en] Lands that were contaminated with radioactive elements following the Fukushima Daiichi Nuclear Power Plant accident in 2011 have been decontaminated, and the construction of an interim storage facility for radioactive waste is planned. A GPS monitoring system was developed to concomitantly determine a location and measure the radiation level at the location. Moreover, a mapping system that produces radiation maps at the measurement locations and also predicts post-decontamination radiation maps using the compiled Monte Carlo simulation program was constructed. These systems were used for decontamination planning and estimation of the decontamination effect. An LED-coupled scintillating fiber detector was developed for visually monitoring radiation in real time at the interim storage facility. The LEDs display different colors corresponding to different radiation levels at the measurement locations along the fiber detector, the maximum length of which is 50 m. Thus, the radiation levels at all positions along the length of the detector can be visually monitored in real time. Moreover, it is useful for radiation safety and for risk communication with radiation workers and residents close to the site. (author)
Journal
Shimizu Kensetsu Kenkyu Hokoku; ISSN 0289-8330; ; (no.93); p. 11-18
; (no.93); p. 11-18
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