scholarly journals Investigations of radiation exposures in the aftermath of the Chernobyl accident

2021 ◽  
pp. 198-205
Author(s):  
R. Michel ◽  
L. Romanchuk
Keyword(s):  
Thyroid Gland ◽  
Radiation Exposure ◽  
Half Life ◽  
Nuclear Power ◽  
Power Plants ◽  
Exposure Dose ◽  
Radioactive Fallout ◽  
Inert Gases ◽  
Human Thyroid ◽  
Natural Radiation

Long-term assessment of the aftermath of the Chernobyl and Fukushima accidents deals with the study of radionuclide emissions and radiation exposure in heavily polluted regions. A signifcant difference in the composition and nature of radionuclide emissions during accidents at nuclear power plants is considered in the study - a largescale radioactive fallout transfer and precipitation over the USSR and Europe took place in Chernobyl due to the uncovered core of the reactor while at Fukushima a massive emission of inert gases occurred. It is noted that based on the density of precipitation, the data indicating that the vital doses of 137Cs remain signifcantly lower or within the range of natural radiation exposure were obtained. However, due to a short half-life (8.0 days) of 131I, there are no available comprehensive measurements of 131I exposure after the accident. It is noted that retrospective dosimetry of the effect of 131I on the thyroid gland through 129I with a half-life of 15.7 Ma allows to fll the gap in this issue. 137Cs precipitation was analyzed by gamma spectrometry, 129I was studied by accelerating mass spectrometry in soil samples from 60 places in zones II and III in the north of Ukraine and the thyroid gland radiation dose in the population. Critical comparing of the results obtained with those of rare direct measurements of 131I activity in the human thyroid gland reveal that the doses are at the lower limit. The actual radiation exposure in the contaminated regions of Northern Ukraine was considered by estimating the exposure dose in returnees in the village of Khrystynivka where 30 families live and consume locally produced products in the evacuated zone II, 75 km from the Chernobyl NPP. The results show that the additional irradiation with 137Cs the returnees received was low. The possibility of safe living in heavily polluted areas is noted. Under the normal way of life, the total radiation exposure of Khrystynivka village residents was within the natural radiation exposure range. Key words: radioactive fallout, radiation exposure, radiation pollution, irradiation of returnees.

scholarly journals Occupational ALARA Planning for Reactor Pressure Vessel Dismantling at Kori Unit 1

2020 ◽  
Vol 17 (15) ◽  
pp. 5346
Author(s):  
Juyoul Kim ◽  
Batbuyan Tseren
Keyword(s):  
Radiation Exposure ◽  
Pressure Vessel ◽  
Nuclear Power ◽  
Power Plants ◽  
Occupational Safety ◽  
Health Management ◽  
Primary Component ◽  
Reactor Pressure Vessel ◽  
Safety And Health ◽  
Reactor Pressure

Assessing workers’ safety and health during the decommissioning of nuclear power plants (NPPs) is an important procedure in terms of occupational radiation exposure (ORE). Optimizing the radiation exposure through the “As Low As Reasonably Achievable (ALARA)” principle is a very important procedure in the phase of nuclear decommissioning. Using the VISIPLAN 3D ALARA planning tool, this study aimed at assessing the radiological doses to workers during the dismantling of the reactor pressure vessel (RPV) at Kori NPP unit 1. Fragmentation and segmentation cutting processes were applied to cut the primary component. Using a simulation function in VISIPLAN, the external exposure doses were calculated for each work operation. Fragmentation involved 18 operations, whereas segmentation comprised 32 operations for each fragment. Six operations were additionally performed for both hot and cold legs of the RPV. The operations were conducted based on the radioactive waste drum’s dimensions. The results in this study indicated that the collective doses decreased as the components were cut into smaller segments. The fragmentation process showed a relatively higher collective dose compared to the segmentation operation. The active part of the RPV significantly contributed to the exposure dose and thus the shielding of workers and reduced working hours need to be considered. It was found that 60Co contained in the stainless steel of the reactor vessel greatly contributed to the dose as an activation material. The sensitivity analysis, which was conducted for different cutting methods, showed that laser cutting took a much longer time than plasma cutting and contributed higher doses to the workers. This study will be helpful in carrying out the occupational safety and health management of decommissioning workers at Kori NPP unit 1 in the near future.

The Development of Radiation-Resistant RF Tags for Use at Nuclear Power Plants

2013 ◽  
Author(s):  
Nobuyuki Teraura ◽  
Kunio Ito ◽  
Naoki Takahashi ◽  
Kouichi Sakurai
Keyword(s):  
Radiation Exposure ◽  
Radiation Damage ◽  
Radio Frequency Identification ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Automatic Data ◽  
Radiation Resistant ◽  
Rf Tags ◽  
Rf Tag

RF tags based on RFID (Radio-frequency Identification) technology have been widely used in various fields including power plant construction and maintenance for the purpose of improving the identification and traceability of the many components in the facility. To date, various types of tags have been developed, including tags that are resistant to chemicals or high-temperature environments, which are used in specialized fields. When considering widespread use of RF tags in nuclear power plants, there is a concern about the effects of radiation on the RF tags, because the data stored in the tag may receive radiation damage, resulting in corruption of data. Here, we describe a newly designed RF tag that achieves resistance to radiation damage by attaching a radiation shield layer and incorporating automatic data-correction software. This radiation-resistant RF tag has been tested under real radiation exposure fields to verify the intended radiation-resistant functions. It is expected that the use of these radiation-resistant RF tags with a data reader and database system will increase the capabilities of RF tags applied to nuclear power plants and it is also expected to lead to reductions in worker radiation exposure doses.

scholarly journals Evaluation of Environmental Contamination and Estimated Radiation Exposure Dose Rates among Residents Immediately after Returning Home to Tomioka Town, Fukushima Prefecture

2019 ◽  
Vol 16 (9) ◽  
pp. 1481 ◽  
Author(s):  
Masahiko Matsuo ◽  
Yasuyuki Taira ◽  
Makiko Orita ◽  
Yumiko Yamada ◽  
Juichi Ide ◽  
...  
Keyword(s):  
Radiation Exposure ◽  
Dose Rate ◽  
Environmental Contamination ◽  
Nuclear Power ◽  
Exposure Dose ◽  
Artificial Radionuclides ◽  
Fukushima Prefecture ◽  
Dose Rates ◽  
Living Space ◽  
Radiation Exposure Dose

On 1 April 2017, six years have passed since the Fukushima Daiichi Nuclear Power Station (FDNPS) accident, and the Japanese government declared that some residents who lived in Tomioka Town, Fukushima Prefecture could return to their homes. We evaluated environmental contamination and radiation exposure dose rates due to artificial radionuclides in the livelihood zone of residents (living space such as housing sites), including a restricted area located within a 10-km radius from the FDNPS, immediately after residents had returned home in Tomioka town. In areas where the evacuation orders had been lifted, the median air dose rates were 0.20 μSv/h indoors and 0.26 μSv/h outdoors, and the radiation exposure dose rate was 1.6 mSv/y. By contrast, in the “difficult-to-return zone,” the median air dose rate was 2.3 μSv/h (20 mSv/y) outdoors. Moreover, the dose-forming artificial radionuclides (radiocesium) in the surface soil were 0.018 μSv/h (0.17 mSv/y) in the evacuation order-lifted areas and 0.73 μSv/h (6.4 mSv/y) in the difficult-to-return zone. These findings indicate that current concentrations of artificial radionuclides in soil samples have been decreasing in the evacuation order-lifted areas of Tomioka town; however, a significant external exposure risk still exists in the difficult-to-return zone. The case of Tomioka town is expected to be the first reconstruction model including the difficult-to-return zone.

Remote-Controlled Inspection Robot for Nuclear Facilities in Underwater Environment

2009 ◽  
Author(s):  
Harunobu Okihana ◽  
Keiji Iwata ◽  
Yasuhiro Miwa
Keyword(s):  
Radiation Exposure ◽  
Nuclear Power ◽  
Power Plants ◽  
Ccd Camera ◽  
High Dose ◽  
Nuclear Facilities ◽  
Original Design ◽  
Inspection Robot ◽  
Manual Inspection ◽  
Underwater Environment

A remote-controlled inspection robot for nuclear facilities in underwater environment was developed. The Array system of Eddy Current Testing (Array-ECT) is installed on the existing robot that consists of the driving unit and the inspection unit with enlarged Charge-Coupled Device (CCD) camera. It can swim in the tank, crawl on the inner surface of the tank, stay on the inspection area and by its two devices, Array-ECT and enlarged CCD camera, start inspection. Array-ECT can record the color contour image, and also can display oscillograph. This technology had been developed in order to reduce worker’s radiation exposure and improve inspection-ability in nuclear power plants for some Radioactive Waste (RW) tanks. With conventional manual inspection, RW tanks must be examined with the sequence of (a) full drainage and decontamination, (b) scaffolding set-up with workers under high dose, and (c) manual inspection. As such, the inspection is time consuming and workers should have high radiation exposure. With the original robot that has only enlarged CCD camera, inspection can be performed without tank drainage and with minimum worker’s radiation exposure. However, it needs experienced inspector for interpretation of visual examination using enlarged CCD camera. Newly developed robot with Array-ECT and enlarged CCD camera can achieve the same performance using the original robot and an experienced inspector for visual inspection using enlarged CCD camera. The new feature added to the original design (i.e. Array-ECT) eliminates the need for an experienced inspector.

Using Probabilistic Criteria in an Assessment of the Potential Radiological Consequences of the Decommissioning of a Nuclear Research Reactor

2013 ◽  
Author(s):  
Christian Wallner ◽  
Anna-Maria Rall ◽  
Severin Thummerer
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Research Reactor ◽  
Nuclear Research ◽  
Exposure Dose ◽  
Occurrence Frequency ◽  
Normal Operation ◽  
Nuclear Facilities ◽  
Nuclear Research Reactor

In order to assess the risk of radiological consequences of incidents and accidents in nuclear facilities it is important to contemplate their frequency of occurrence. It has to be shown that incidents and accidents occur sufficiently seldom according to their radiological consequences i. e. the occurrence frequency of radiological doses has to be limited. This is even demanded by the German radiation protection ordinance (StrlSchV), which says that in nuclear facilities other than nuclear power plants (NPP) in operation and for decommissioning, the occurrence frequency of incidents and accidents shall be contemplated in order to prove the design of safety measures and safety installations. Based on the ideas of the ICRP64, we developed a risk based assessment concept for nuclear facilities, which fulfils the requirements of the German regulations concerning dose limits in normal operation and design basis accidents. The general use of the concept is dedicated to nuclear facilities other than nuclear power plants (NPP) in operation and for decommissioning, where the regulation of risk assessment is less sophisticated. The concept specifies occurrence frequency limits for radiation exposure dose ranges, i. e. the occurrence frequency of incidents and accidents has to be limited according to their radiological effects. To apply this concept, scenarios of incidents and accidents are grouped in exposition classes according to their resulting potential effective dose to members of the general public. The occurrence frequencies of the incidents and accidents are summarized in each exposition class whereas the sum must not exceed the frequency limits mentioned above. In the following we introduce the application of this concept in the assessment of the potential radiological consequences of the decommissioning of a nuclear research reactor. We carried out this assessment for the licensing process of the decommissioning on behalf of German authorities.

THE VALIDATION OF COMPREHENSIVE SOFTWARE FOR THE ASSESSMENT OF RADIOLOGICAL IMPACTS ON HUMANS THROUGH BENCHMARK ANALYSIS WITH RADIOLOGICAL CODES

2020 ◽  
Vol 190 (3) ◽  
pp. 250-268
Author(s):  
Ali Haghighi Shad ◽  
Mitra Athari Allaf ◽  
Darioush Masti ◽  
Kamran Sepanloo ◽  
Seyed Amir Hossein Feghhi
Keyword(s):  
Thyroid Gland ◽  
Effective Dose ◽  
Nuclear Power ◽  
Power Plants ◽  
Whole Body ◽  
The Public ◽  
Loss Of Coolant Accident ◽  
Initial Stage ◽  
Loss Of Coolant ◽  
Accident Conditions

Abstract In this paper, a novel domestic code called KIANA was developed for the assessment of radiological impacts on the population in normal and accident conditions including design basis accident (DBA) and beyond DBA (BDBA) for the nuclear power plants. The validation process of the KIANA code was performed using the results of the DOZA_M radiological code, whose results are presented in the Final Safety Analysis Report (FSAR) of the Bushehr Nuclear Power Plant Unit One (BNPP-1). The calculations of KIANA are performed based on the Gaussian diffusion model. The developed KIANA code has the potential of calculating the concentration and radionuclide doses due to the pathways such as airborne, foodstuff, marine (both one and two boxes models), soils, animals, vegetation (with and without tritium) and other pathways without any restriction. In the current research, the individual dose from a cloud to the member of the public in the region of BNPP-1 in normal condition was calculated. Moreover, the total effective dose to the member of the public from the primary to the secondary leakage inside steam generators, large break loss-of-coolant accident (LBLOCA) and small break loss-of-coolant accident was calculated. Thyroid gland equivalent dose for the infant (1–8 years) in the case of LBLOCA at the BNPP in DBA conditions was also evaluated. Finally, the prevented dose at the initial stage for the whole body of adults after BDBA, prevented dose at the initial stage for the thyroid gland of children after BDBA and the effective dose during the first year after the accident (external body irradiation from presence in the area) in the case of BDBA are assessed. The KIANA simulation results showed a good agreement with the FSAR data of BNPP.

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