Environmental remediation following the Fukushima-Daiichi accident

Conference · Mon Jul 01 04:00:00 EDT 2013

OSTI ID:22264135

Tagawa, A.; Miyahara, K.; Nakayama, S. ^[1]

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1. Japan Atomic Energy Agency - JAEA, 4-49 Muramatsu, Tokai-mura, Naka-gun, Ibaraki 319-1184 (Japan)

A wide area of Fukushima Prefecture was contaminated with radioactivity released by the Fukushima Daiichi nuclear accident. The decontamination pilot projects conducted by JAEA aimed at demonstrating the applicability of different techniques to rehabilitate affected areas. As most radioactive cesium is concentrated at the top of the soil column and strongly bound to mineral surfaces, there are 3 options left to decrease the gamma dose rate (usually measured 1 m above the ground surface): the stripping of the contaminated topsoil (i.e. direct removal of cesium), the dilution by mixing and the soil profile inversion. The last two options do not generate waste. As the half-distance of {sup 137}Cs gammas in soil is in the order of 5-6 cm (depending on density and water content), the shielding by 50 cm of uncontaminated deep soil would theoretically reduce gamma doses by about 3 orders of magnitude. Which option is employed depends basically on the Cesium concentration in the topsoil, averaged over a 15-cm thickness. The JAEA's decontamination pilot projects focus on soil profile inversion and topsoil stripping. Two different techniques have been tested for the soil profile inversion: one is the reversal tillage by which surface soil of thickness of several tens of cm is reversed by using a tractor plough and the other is the complete interchanging of contaminated topsoil with uncontaminated subsoil by using a back-hoe. Reversal tillage with a tractor plough cost about 30 yen/m{sup 2}, which is an order of magnitude lower than that of topsoil-subsoil interchange (about 300 yen/m{sup 2}). Topsoil stripping is significantly more costly (between 550 yen/m{sup 2} and 690 yen/m{sup 2} according to the equipment used)

• Research Organization: American Nuclear Society, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
• OSTI ID: 22264135
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
54 ENVIRONMENTAL SCIENCES
ABUNDANCE
CESIUM
CESIUM 137
CONCENTRATION RATIO
CULTIVATION TECHNIQUES
DECONTAMINATION
DOSE RATES
ECOLOGICAL CONCENTRATION
FUKUSHIMA DAIICHI NUCLEAR POWER STATION
HUMIDITY
JAEA
REACTOR ACCIDENTS
REMEDIAL ACTION
SOILS
STRIPPING
THICKNESS