The Japanese Journal of Health Physics, which is the journal of the Japan Health Physics Society (JHPS), has so far published many articles related to the severe accident at Tokyo Electric Power Company (TEPCO)’s Fukushima Daiichi Nuclear Power Station (1F) that occurred in 2011 [1]. This paper provides an overview of the 39 articles: (1) three special articles, (2) nine original papers and three notes, (3) three reviews and five technical data articles, and (4) 16 reports, letters, topics, and Japan to the World (J to W). This review provides an outline of these 39 articles.

The three special articles were: ‘Radiocaesium contamination in Fukushima prefecture’ (2011) by Kawata [2]; ‘Detailed investigation on contamination around the Fukushima site’ (2011) by Saito [3]; and ‘Analysis on the atmospheric dispersion of radioactive materials’ (2012) by Nagai [4]. Kawata’s article [2], in addition to reporting on the contamination situation, suggested that a comprehensive balance between residents’ desires and the limits and distribution of financial resources was important for environmental restoration, and that the active participation of local governments and residents was necessary to make decisions and establish a system that could facilitate such decisions. Kawata [2] also expressed expectations for the JHPS to contribute to the presentation of guidelines for the specific application of International Commission on Radiological Protection (ICRP) Publication 111 [5] and the realization of sharing the concept of the recommendations with local residents and the public. Saito’s article [3] reported on the work of soil survey and contamination mapping by car-borne surveys conducted mainly by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), and the generation of a database. Expectations were also indicated for the use of these data in dose assessment, environmental impact evaluation, development of transfer models, and future predictions. Nagai’s article [4] outlined the estimation of atmospheric emissions and atmospheric dispersion analysis using the Worldwide version of System for Prediction of Environmental Emergency Dose Information (WSPEEDI-II) atmospheric dispersion prediction system.

The nine original papers were: ‘Estimation of dose from the measurement results of airborne radionuclide concentrations following the Fukushima Dai-ichi Nuclear Power Plant accident’ (2013) by Takeyasu et al. [6]; ‘¹³⁷Cs Environmental half-life without remediation: impact on radiation dose’ (2016) by Brooks et al. [7]; ‘Environmental radiation monitoring and external dose estimation in Aomori prefecture after the Fukushima Daiichi Nuclear Power Plant accident’ (2016) by Hosoda et al. [8]; ‘Performance evaluation and usage guidelines for iodine adsorption cartridges for gas respirators under similar environmental conditions to those of the accident at the Fukushima Daiichi Nuclear Power Station’ (2016) by Nakayama et al. [9]; ‘Evaluation of gamma-ray spectra measured inside and outside a house in Fukushima’ (2016) by Tanimura et al. [10]; ‘Radiochemical analysis of rubble collected from Fukushima Daiichi Nuclear Power Station’ (2016) by Sato et al. [11]; ‘Transfer factors of tellurium and cesium from soil to radish (Raphanus sativus var. sativus) and komatsuna (Brassica rapa var. perviridis)’ (2017) by Fujiwara et al. [12]; ‘Improvement of estimation of 131I concentrations in the air using data measured by monitoring posts applied by determination of passing-through time of plume using noble gas counts’ (2017) by Yamada et al. [13]; and ‘Gastrointestinal absorption rate in rats for radiocesium in soil collected near Fukushima Power Plant or doped artificially with ¹³⁴CsCl’ (2019) by Iwata et al. [14].

The study by Takeyasu et al. [6] estimated the committed effective dose doses for adults and committed equivalent dose to thyroid of infants in the vicinity of Tokai village using the measured results and considering realistic parameters. The estimated committed effective dose doses for adults and committed equivalent dose to thyroid of infants were approximately one-sixth and one-ninth of the provisional values estimated according to a method similar to that used to calculate predicted doses (staying outdoors and taking no protective measures). The study by Brooks et al. [7] discussed how historical data on the environmental half-life of ¹³⁷Cs in milk and humans from fallout during nuclear testing would change and affect dose in the absence of remedial action. These authors noted that if decontamination, etc., had been implemented, the dose to Utah farmers would have been reduced by almost a factor of 10 as a function of the effective ¹³⁷Cs half-life of 104 days. Hosoda et al. [8] conducted a survey of Aomori prefecture after the accident at 1F using a vehicle equipped with a NaI(Tl) scintillation spectrometer and found that the contribution of ¹³⁴Cs and ¹³⁷Cs to the absorbed dose rate in air was negligible. The study by Nakayama et al. [9] evaluated the performance of iodine adsorption cartridges installed in gas respirators and powered air purifier respirators under conditions simulating those after the 1F accident. Some cartridges maintained effective removal of radioactive iodine for more than 10 hours, whereas the performance of other cartridges decreased as relative humidity increased. The study clearly presented the measured concentrations after purification for each cartridge. The study by Tanimura et al. [10] examined a simple method for evaluating γ-ray spectra that evaluated the effectiveness of shielding by actual measurements, and measured γ-ray spectra inside and outside a house in the Baba district of Minami-Soma city. The authors stated that scattered rays were more abundant indoors than outdoors, and the dose contribution tended to exceed 50%. The study by Sato et al. [11] conducted radiochemical analysis of debris collected in the 1F reactor buildings (unit 1, unit 2, and unit 3), and based on the radioactivity data of ³H, ¹⁴C, ⁶⁰Co, ⁹⁰Sr, ⁹⁴Nb, ⁹⁹Tc, ¹³⁷Cs, ¹⁵²Eu, ¹⁵⁴Eu, ²³⁸Pu, ^239+240Pu, ²⁴¹Am, and ²⁴⁴Cm, they reported a comparison for each reactor unit and discussed the status of each unit based on the radioactivity data. The study by Fujiwara et al. [12] investigated soil retention of Te and its transfer from soil to plant, and values of transfer factors of Te from various soils to radish and komatsuna were presented. Yamada et al. [13] devised a new method to determine the time period of plume passage from the time variation of the noble gas ¹³³Xe counts that does not require consideration of deposition processes. Application of this method allowed estimation of the ¹³¹I concentration in the air, which was within a factor of three of the measured values. Iwata et al.’s study [14] investigated the systemic retention of soil-derived radioactive Cs in rats using three types of soil and other materials containing ¹³⁴Cs and ¹³⁷Cs collected in Fukushima prefecture. The biological half-life of radioactive Cs was determined to be 2.9– 7.9 hours.

The three notes were: ‘Root uptake of radiocesium by a mini cabbage growing on various potting soils’ (2013) by Ishii et al. [15]; ‘Investigation of absorbed dose rate in air by a carborne survey in Namie town, Fukushima prefecture’ (2016) by Pornnumpa et al. [16]; and ‘Elution suppression treatment of radioactive cesium in municipal solid waste incineration fly ash using water-repellent spray’ (2021) by Koike et al. [17]. Ishii et al. [15] investigated the transfer of ¹³⁷Cs from soil contaminated with radioactive Cs, including Akadama soil, leafmold soil, and sludge soil generated from water purification to mini cabbages. The authors stated that ¹³⁷Cs was easily transferred to mini cabbages if the Akadama soil was contaminated. Pornnumpa et al. [16] examined absorbed dose rates from car-borne surveys in the town of Namie town and noted that the averages were 3.7 μGy/hr in 2011, 1.2 μGy/hr in 2014, and 0.9 μGy/hr in 2015. Koike et al.’s note [17] examined whether the elution of water-soluble radioactive Cs could be suppressed by simply spraying a commercially available waterproof spray (water repellent) on municipal solid waste incineration fly ash containing radioactive Cs. They found that the elution rate of water-soluble radioactive Cs in incineration fly ash was reduced by about half by simply spraying with the commercially available water repellent.

The three reviews were: ‘Resuspension and transfer of radioactive particulate matter and subsequent secondary contamination’ (2014) by Akimoto [18]; ‘Development of GPSlinked radiation measurement systems KURAMA/KURAMAII’ (2015) by Tanigaki [19]; and ‘Development and issues of air dose rate monitoring systems in Fukushima prefecture with emphasis on portable monitoring posts’ (2017) by Akimoto [20]. Akimoto [18] reviewed the resuspension and eolian transfer of terrestrial particulate matter, one of the dominant processes of radioactive material transfer, with a focus on windoriginated mechanisms. Tanigaki [19] introduced an overview of KURAMA/KURAMA-II, which was developed to rapidly and precisely determine the distribution of air dose rates. His review covered the development of the systems, testing, and operation status, and findings obtained to date. Akimoto [20] provided a detailed review of the evolution of the air dose rate monitoring system for terrestrial areas of Fukushima prefecture before and after the accident, and clearly identified the issues of the system.

The three technical data articles published in Japanese were: ‘The result of radionuclide concentrations in fallout around Tokai reprocessing plant after Fukushima Daiichi Nuclear Power Plant accident’ (2013) by Nagaoka et al. [21]; ‘Distribution of ¹²⁹I, ¹³⁴Cs, and ¹³⁷Cs in the Eastern area off Cape Shiriya, Aomori prefecture’ (2017) by Gasa et al. [22]; and ‘Setting of the normal variation range for the environmental radiation monitoring around the Tokai reprocessing plant after the TEPCO’s nuclear accident’ (2017) by Nakano et al. [23].

Nagaoka et al. [21] reported the results for total beta activity and γ-ray nuclide analysis of fallout dust around the Tokai reprocessing plant for a year and a half after the 2011 accident, and provided 90Sr and Pu analyses of some samples. Gasa et al. [22] analyzed the distributions of ¹²⁹I, ¹³⁴Cs, and ¹³⁷Cs in the sea area east of Cape Shiriya and presented the results of their study on the water mass structure. Nakano et al. [23] evaluated the normal variation range after the 1F accident to help identify whether observed activity concentrations were due to the accident or to releases from the Tokai reprocessing plant. This method was necessary because the 1F accident prevented updating the normal range used in evaluating environmental radiation monitoring results around the Tokai reprocessing plant.

The two technical data articles published in English were: ‘In situ gamma spectrometry intercomparison in Fukushima, Japan’ (2015) by Mikami et al. [24]; and ‘Using experimental transfer factors to estimate the ratio between the committed effective dose from ingestion of radio-tellurium to that of radio-cesium released by the Fukushima Daiichi Nuclear Power Plant accident’ (2018) by Takahashi et al. [25]. Mikami et al. [24] reported the results of an intercomparison of in situ gamma spectrometry in contaminated areas by teams participating in a government-led project to map the distribution of radionuclides. Takahashi et al. [25] presented the calculated ratio of committed effective doses of radioactive Te and radioactive Cs using experimental transfer factors to estimate the ratio of the effective dose from the intake of radioactive Te to the effective dose from the intake of radioactive Cs released due to the 1F accident, and they compared the results with those calculated using transfer factors estimated in an International Atomic Energy Agency (IAEA) report [26].

The five reports were: ‘Radioactive contamination of towels with the soil containing radioactive cesium and its removal by washing’ (2012) by Fujiwara et al. [27]; ‘Transfer of tellurium and cesium from nutrient solution to radish (Raphanus sativus var. sativus) and their distribution in the plant’ (2015) by Fujiwara et al. [28]; ‘The effect of soil sterilization on the ¹³⁷Cs transfer from soil to radish (Raphanus sativus var. sativus)’ (2015) by Hattori et al. [29]; ‘Investigation of removal factors of various materials inside houses after nuclear power station accident’ (2019) by Mori et al. [30]; and ‘A knowledge-sharing activity on the environmental radiation monitoring results affected by Fukushima-Daiichi Nuclear Power Plant accident at Tokai-Oarai area in Ibaraki prefecture’ (2020) by Nakano et al. [31].

Fujiwara et al. [27] reported on their investigation results for the rate of adhesion of contaminated soil and the rate of removal by washing on several types of standard toweling fabrics. In a second later report Fujiwara et al. [28] looked at the transfer of Te and Cs from nutrient solution to radish and the distribution of radioactivity in the plant. Hattori et al. [29] studied the effect of soil sterilization on the transfer of ¹³⁷Cs from soil to radish and found that the concentration of ¹³⁷Cs in radish grown in sterilized soil was significantly higher. Mori et al. [30] presented results of a survey on the wiping efficiency of various materials inside houses in Okuma, Futaba, and Namie towns. Nakano et al. [31] summarized results from ‘The review meetings of environmental effects from the 1F accident’ established after the accident as a forum for experts from related facilities within the Japan Atomic Energy Agency (JAEA) to exchange opinions on environmental radiation (radioactivity) fluctuations due to the accident from a technical perspective, to exchange other information, collect data, and to study various issues.

One letter appeared: ‘Supplementary explanation to “The result of radionuclide concentrations in fallout around Tokai reprocessing plant after Fukushima Daiichi Nuclear Power Plant accident’ (2013) by Nagaoka et al. [32]. The supplemental explanation was provided in response to a reader’s question about the results of a survey on the concentration of radioactive materials in fallout after the accident at 1F in the vicinity of the Tokai reprocessing plant; the reader stated that the radioactivity ratios were too low.

One topics was published: ‘The report of the ICRU expert workshop on radiation monitoring for protection of the public after major radioactive releases to the environment: feedback from the accident at the Fukushima Daiichi NPS’ (2017) by Kanda et al. [33]. This topics article described the Chair’s report in the keynote session on the International Commission on Radiation Units and Measurements (ICRU) report that was then under preparation, and the programs and systems of radiation monitoring in session III and the summary of reports in post-accident monitoring at Chernobyl and Fukushima in session V were also described.

The nine from J to W articles were: ‘Radiation dose map of Japan using an aircraft: visually grasping the influence of the accident’ (2013) by the JAEA [34]; ‘Decontamination of playground lot: trial decontamination and its effects on air radiation dose rate’ (2013) by the JAEA [35]; ‘Measures against radiation and Fukushima prefecture’s environmental creation centre’ (2013) by Katayose [36]; ‘Effects of forest decontamination on the reduction in external exposure doses: field demonstration of forest decontamination’ (2014) by the JAEA [37]; ‘Development of a depth distribution monitor of radioactivity concentration in the soil’ (2015) by Hora et al. [38]; ‘Visualization of the distribution of radiocesium concentration at the bottom of irrigation ponds: measurement of irrigation ponds using the plastic scintillation fiber’ (2015) by the JAEA [39]; ‘Investigation of the concentrations of radionuclides in seabed sediments: the spatial distribution of radionuclides in seabed sediments off the Ibaraki coast’ (2017) by the JAEA [40]; ‘New technology for suppressing cesium migration from forests: mild regeneration of village forests with polymers and clay’ (2018) by the JAEA [41]; and ‘Organizations and activities of Fukushima prefectural centre for environmental creation’ (2018) by the Fukushima prefectural center for environmental creation [42].

The JAEA conducted a survey using a helicopter equipped with NaI(Tl) and global positioning system (GPS), and produced a map of dose rates converted to those at 1 m above ground level [34]. Furthermore, the JAEA reported results of a pilot decontamination of parks and playgrounds in residential areas to expand outdoor activity areas for children [35]. Katayose [36] gave an overview of environmental monitoring activities conducted by Fukushima prefecture immediately after the accident and the prefecture’s efforts to improve the environment. In the fourth from J to W article, the JAEA reported that removal of the deciduous layer of leaves and branches within 10 m from a forest boundary was the most effective way to reduce residents’ radiation dose based on the result of a forest decontamination demonstration [37]. Hora et al. [38] developed a monitor to measure Cs concentration depth distribution in contaminated soil and introduced the monitor configuration and estimation method. The JAEA visualized the radiocesium concentration at the bottom of an irrigation pond obtained using a plastic scintillation fiber detector [39]. JAEA also continuously investigated radioactivity concentrations in seabed sediments, seawater, and marine organisms along the coast of Ibaraki prefecture in the period prior to the accident and leading up to the J to W report publication [40]. Finally, in collaboration with Ibaraki University, Kumagaigumi Co., Ltd. and its group of companies, JAEA developed a new technology using polyelectrolytes (with are polymers electric charges and clay minerals) to control Cs migration using natural forces such as rainfall and rainwater runoff [41]. The ninth from J to W report was made by the Fukushima prefectural center for environmental creation, and the organization and its activities were introduced [42].

This paper presented an overview of 39 articles on environmental monitoring published in the Japanese Journal of Health Physics from 2011 through March 2022. The articles covered the systems that were put in place following the 1F severe accident and the development of environmental monitoring and decontamination techniques, and it summarized the valuable experiences of the time. It is the hope of the authors that readers use this review as a starting point from which they move on to the original articles of interest to them.