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Journal Articles

Measurement of ambient dose equivalent rates by walk survey around Fukushima Dai-ichi Nuclear Power Plant using KURAMA-II until 2016

Ando, Masaki; Yamamoto, Hideaki*; Kanno, Takashi*; Saito, Kimiaki

Journal of Environmental Radioactivity, 190-191, p.111 - 121, 2018/10

 Times Cited Count:12 Percentile:54.36(Environmental Sciences)

Ambient dose equivalent rates in various environments related to human lives were measured by walk surveys using the KURAMA-II systems from 2013 to 2016 around the Fukushima Dai-ichi Nuclear Power Plant. The dose rate of the locations where the walk survey was performed decreased to about 38% of its initial value in the 42 months, which was beyond that attributable to the physical decay. The air dose rates decreased depending on the level of the evacuation areas, and the decrease was slightly larger in populated areas where humans are active. The comparison of walk survey data with car-borne survey data indicated that the air dose rate varies largely even within a 100 m square area. The dose rates measured by the walk surveys were estimated to be medial of those along roads and those of undisturbed flat ground. The air dose rates measured by the walk surveys decreased quickly compared with the air dose rate from the flat ground measurement.

JAEA Reports

Development of elemental components in NDA systems for certifying radioactive wastes with the clearance level

Tsutsumi, Masahiro; Oishi, Tetsuya*; Yamasoto, Kotaro; Yoshida, Makoto

JAERI-Research 2004-021, 43 Pages, 2004/12

JAERI-Research-2004-021.pdf:8.55MB

We have designed and developed a $$gamma$$ measurement system to certify radioactive wastes below the clearance level. By advancing non-destructive $$gamma$$-ray assay technology, it aims at quantitative determination of radionuclides contained in 200 litter drum/container wastes. Unlike the waste from a nuclear power plant, you have to assume that the waste originating from radioisotope usage and nuclear research laboratory have a variety of contents and a complex mixture of radionuclides, and furthermore the uniformity of activity concentration is unknown. To cope with the problems, we have developed the $$gamma$$-ray measuring instruments (units) with effective improvement of capability against each problem. They are (1) germanium $$gamma$$ spectrometry unit for enhanced peak identification, (2) positioning detection unit for positioning of $$gamma$$ interactions and (3)high-efficiency detection unit for separation of low-energy component. This report summarizes the direction of the clearance level measuring system and the three developed measuring units with their performances.

Journal Articles

Design of an anti-compton spectrometer for low-level radioactive wastes using Monte Carlo techniques

Tsutsumi, Masahiro; Oishi, Tetsuya; Kinouchi, Nobuyuki; Sakamoto, Ryuichi; Yoshida, Makoto

Journal of Nuclear Science and Technology, 39(9), p.957 - 963, 2002/09

 Times Cited Count:3 Percentile:24.08(Nuclear Science & Technology)

An anti-Compton spectrometer with semi-2$$pi$$ Compton suppression is designed to identify the photons emitted from low-level radioactive wastes from radioisotope usage and nuclear research laboratory. Since the objective sample is massive and large, the system has a full opening towards the sample position. The characteristics and features of the system concerning Compton suppression and reduction of the background component due to natural radioactive source are estimated by the Monte Carlo simulations. The anti-Compton technique is shown to be quite advantageous for the reduction of the surrounding natural background radiation, as well as the suppression of the background for the higher energy photons.

Journal Articles

Simultaneous counting of $$alpha$$,$$beta$$ and $$gamma$$ rays with phoswich detectors

Usuda, Shigekazu; Abe, Hitoshi; Mihara, Akira

Journal of Alloys and Compounds, 213-214, p.437 - 439, 1994/00

 Times Cited Count:11 Percentile:64.86(Chemistry, Physical)

no abstracts in English

Journal Articles

Phoswich detectors combining doubly or triply ZnS(Ag), NE102A, BGO and/or NaI(Tl) scintillators for simultaneous counting of $$alpha$$, $$beta$$ and $$gamma$$ rays

Usuda, Shigekazu; Abe, Hitoshi; Mihara, Akira

Nuclear Instruments and Methods in Physics Research A, 340, p.540 - 545, 1994/00

 Times Cited Count:26 Percentile:88.43(Instruments & Instrumentation)

no abstracts in English

JAEA Reports

Data catalog of gamma ray response function for NaI(Tl) scintillation detectors by the Monte Carlo calculation

Saito, Kimiaki; Moriuchi, Shigeru

JAERI 1306, 121 Pages, 1987/08

JAERI-1306.pdf:4.02MB

no abstracts in English

Journal Articles

Distribution of $$gamma$$ and cosmic ray exposure rates in a 12-storied concrete building

Radiat.Prot.Dosim., 18(4), p.221 - 228, 1987/04

 Times Cited Count:6 Percentile:56.3(Environmental Sciences)

no abstracts in English

Journal Articles

Intercomparison between EML method and JAERI method for the measurements of environmental $$gamma$$-ray exposure rates

Radiat.Prot.Dosim., 18(2), p.81 - 87, 1987/02

 Times Cited Count:5 Percentile:51.22(Environmental Sciences)

no abstracts in English

Journal Articles

Monte Carlo calculation of NaI(Tl)detector response functions for low energy gamma rays

;

Nuclear Instruments and Methods in Physics Research A, 226(2-3), p.449 - 454, 1984/00

 Times Cited Count:11 Percentile:78.67(Instruments & Instrumentation)

no abstracts in English

JAEA Reports

JAEA Reports

JAEA Reports

Journal Articles

Monte Carlo calculation of accurate response functions of a NaI(Tl) detector for gamma rays

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Nuclear Instruments and Methods, 185(1), p.299 - 308, 1981/00

no abstracts in English

Journal Articles

A Method of computer analysis of a NaI(Tl) $$gamma$$-ray spectrum

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Nuclear Instruments and Methods, 127(2), p.261 - 263, 1975/02

no abstracts in English

Oral presentation

Development of a method for discriminating the influence of the radon progenies in air from aerial radiation monitoring data

Hirouchi, Jun; Nishizawa, Yukiyasu*; Urabe, Yoshimi*; Shimada, Kazumasa; Sanada, Yukihisa; Munakata, Masahiro

no journal, , 

After the Fukushima Dai-ichi Nuclear Power Station (NPS) accident, a series of aerial radiation monitoring (ARM) was conducted as a national project to map the ground surface distribution of radiocesium. The influence of $$gamma$$-rays from natural nuclides, especially the radon progenies (Pb-214 and Bi-214) should be excluded from the ARM measurement data to accurately estimate deposition of artificial radionuclides. Therefore, the aim of this study is to develop a method for discriminating the influence of the radon progenies in air from the measurement data. The discrimination method was applied to the ARM data around Sendai NPS and we compared the dose rate at a height of 1 m above the ground measured by NaI survey meter with the ARM data. The coefficient of determination (R2) and normalized mean square error (NMSE) were improved by applying the method, showing that the validity of the method was confirmed.

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