Radiocaesium contamination of bamboo shoots in Fukushima and surrounding regions after the Fukushima nuclear accident

Journal of Radioanalytical and Nuclear Chemistry - Radiocaesium contamination of bamboo shoots was characterised using food monitoring data from 2011 to 2015 in Fukushima and surrounding...     

Evaluation of radionuclide concentration in agricultural food produced in Fukushima Prefecture following Fukushima accident using a terrestrial food chain model

Journal of Radioanalytical and Nuclear Chemistry - Ingestion of radionuclide contaminated food is one of the major concerns in long-term exposure following a nuclear accident. A terrestrial food...     

Removal of Radionuclides from Fukushima Daiichi Waste Effluents

This paper describes the processes used at the Fukushima Daiichi plant, Japan, to purify the waste effluents generated in the cooling of damaged reactors. These include primary cesium removal with the Kurion zeolite system and the SARRY system utilizing silicotitanate to remove radiocesium from water recirculated to reactors for cooling. Another process is the ALPS system to purify the retentates of the reverse osmosis plant to further purify the water from radionuclides after primary cesium separation. In ALPS, a major role is played by the transition metal hexacyanoferrate product CsTreat and sodium titanate SrTreat in the removal of radiocesium and radiostrontium, respectively. The performance of these four exchangers (zeolite, silicotitanate, hexacyanoferrate, and sodium titanate) is critically analyzed with respect to processing capacities and the decontamination factors obtained in the processes. Furthermore, general information on preparation, structure and ion exchange of these ion-exchanger categories is given with additional information on their use in nuclear waste effluent treatment processes. Finally, the importance of selectivity and associated factors are discussed.     

The Nuclear Fuel Cycle Back-End after Fukushima

The impact of the Fukushima accident on the nuclear fuel cycle back-end is obvious. In the present paper the various back-end options and their impact on the environment will be presented in view of this new perspective. The partitioning and transmutation (P&T) concept and the direct disposal of nuclear fuel including a very long intermediate storage will certainly be revisited with respect to safety considerations; here the instant release fraction (IRF) and the long-term stability of the fuel matrix under real repository conditions are highly relevant. Furthermore the impact of released radionuclides to the environment will have a higher attention.     

Long-term behavior of 137Cs and 3H activities from TEPCO Fukushima NPP1 accident in the coastal region off Fukushima,Japan

Journal of Radioanalytical and Nuclear Chemistry - Decreasing trends of both 137Cs and 3H activity concentrations and an increasing trend of 3H/137Cs activity ratio at Fukushima Dai-ichi Nuclear...     

Airborne gamma-ray emitters from Fukushima detected in New York State

An air-sampling network that operates continuously as part of New York State’s environmental surveillance program collected radionuclides emitted as a result of the Fukushima nuclear accident. Samples were collected, typically for 7 days each, by drawing ~600 m³ of air through a particulate-collecting filter followed in series by a canister containing activated charcoal. Additional air sampling was implemented at ~3-day intervals at two locations. Gamma-ray spectroscopy was used to confirm the detection of ¹³¹I, ¹³⁷Cs, ¹³⁴Cs, and ⁷Be in the particulate phase at all sites, with maximum concentrations near 1,260, 160, 160, and 5,200 μBq/m³, respectively. Gas-phase ¹³¹I, collected on activated charcoal, exhibited a maximum concentration of 3,400 μBq/m³ at the sites. Assessment of radionuclide levels in the air samples suggests that there were minimal health impacts from the airborne radionuclides as the activities contributed an insignificant amount to the annual human dose.     

Cesium concentrations in various environmental media at Namie,Fukushima

Journal of Radioanalytical and Nuclear Chemistry - The radioactivity of cesium in the water and sediments of two major rivers was measured along with airborne radioactivity in Namie Town, after the...     

Fukushima event reconstruction using modelling and isotope relationships

Using particulate and noble gas raw data analysed from Comprehensive Nuclear Test-Ban-Treaty (CTBT) monitoring sites, Canadian National Surveillance networks and atmospheric transport modelling, it is possible to associate some of the main events in the Fukushima accident timeline with observations, and perturbations in isotopic ratios in Japan, through the Pacific and into North America. Additional sources identified during the accident period will be commented upon in the context of CTBT treaty verification.     

Should we measure plutonium concentrations in marine sediments near Fukushima?

Pu contamination originating from Fukushima accident has not been detected in marine sediment samples collected outside a 30 km circle around the plant. It is shown, by means of numerical modelling, that if any impact from the accident has occurred, this would remain in a very close area to Fukushima because of the low Pu mobility in the marine environment. Since the situation inside the 30 km zone remains unknown, further studies on the determination of Pu isotopes in sediments within this area are required.     

Parallel radioisotope collection and analysis in response to the Fukushima release

In order to co-recycle neptunium, uranium and plutonium using the PUREX process, numerical simulations were used to investigate the behaviors of neptunium in the first solvent extraction cycle. Counter-current extraction experiments using a miniature mixer-settler were performed to verify the simulation. Calculated results based on experiments show that the concentrations of nitric and nitrous acid, saturation of uranium, flow ratio and residence time have important effects on the pathway of neptunium, and accumulation of neptunium may appear with the presence of uranium and plutonium.     

Radio-microanalytical particle measurements method and application to Fukushima aerosols collected in Japan

A nondestructive analytical method based on autoradiography and gamma spectrometry was developed to perform activity distribution analysis for particulate samples. This was applied to aerosols collected in Fukushima Japan, 40 km north of the Daiichi nuclear power plant for a 6 week period beginning shortly after the March 2011 tsunami. For an activity distribution of 990 “hot particles” from a small filter area, the hottest particle was nearly one Bq ^137+134Cs but most of the activity in the filter was produced by particles having <50 mBq each. ¹³⁴Cs/¹³⁷Cs activity ratios corrected to March 20, 2011 ranged from 0.68 (u _c = 28 %) to 1.3 (u _c = 15 %). The average ratio for a large quantity of particles was 0.92 (u _c = 4 %). Virtually all activity collected was beta and not alpha, suggesting little if any direct fuel debris was present at this site and time. These findings are expected to assist with separate efforts to better understand the emission events, radionuclide transport and potential environmental or biological uptake. The methods should be applicable to general environmental, radiotoxicological and similar studies for which activity distribution and particle chemistry are of importance.     

Separation of Zr in the rubble waste generated at the Fukushima Daiichi Nuclear Power Station

Separation method of Zr using trans uranium resin (TRU resin) and tetra valent actinide resin (TEVA resin) was developed for the analysis of ⁹³Zr contained in the rubble waste. Zr, Nb, and U were quantitatively extracted on the TRU resin from 3 M HNO₃ and striped with 0.01 M HF, in addition, some part of Mo, Hg, Bi, and Th were also included in the stripping solution. The stripping solution was evaporated to eliminate HNO₃ and the residue was dissolved in 0.1 M HF. Finally, Zr was separated from Nb and Mo with the TEVA resin.