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

Author(s):  
Christian Wallner ◽  
Anna-Maria Rall ◽  
Severin Thummerer

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.

ANRI ◽  
2020 ◽  
pp. 31-44
Author(s):  
Aleksey Ekidin ◽  
Aleksey Vasil'ev ◽  
Maksim Vasyanovich ◽  
Evgeniy Nazarov ◽  
Mariya Pyshkina ◽  
...  

The article presents the results of field studies in the area of the Belarusian NPP in the pre-operational period. The «background» contents of gamma-emitting radionuclides in individual components of the environment are determined. The main array of dose rate measurements in the area of the NPP construction site is in the range 0.048 ÷ 0.089 μSv/h. External radiation in the surveyed area is formed at 96% due to 40K, 226Ra and 232Th. The information obtained can be used to correctly interpret the data of future radiation monitoring during normal operation of nuclear power plants.


2019 ◽  
Vol 186 (4) ◽  
pp. 524-529
Author(s):  
Si Young Kim

Abstract The intercomparison test is a quality assurance activity performed for internal dose assessment. In Korea, the intercomparison test on internal dose assessment was carried out for nuclear facilities in May 2018. The test involved four nuclear facilities in Korea, and seven exposure scenarios were applied. These scenarios cover the intake of 131I, a uranium mixture, 60Co and tritium under various conditions. This paper only reviews the participant results of three scenarios pertinent to the operation of nuclear power plants and adopts the statistical evaluation method, used in international intercomparison tests, to determine the significance values of the results. Although no outliers were established in the test, improvements in the internal dose assessment procedure were derived. These included the selection of intake time, selection of lung absorption type according to the chemical form and consideration of the contribution of previous intake.


Author(s):  
Sangmyeon Ahn ◽  
Jungjoon Lee ◽  
Chanwoo Jeong ◽  
Kyungwoo Choi

We are having 23 units of nuclear power plants in operation and 5 units of nuclear power plants under construction in Korea as of September 2012. However, we don’t have any experience on shutdown permanently and decommissioning of nuclear power plants. There are only two research reactors being decommissioned since 1997. It is realized that improvement of the regulatory framework for decommissioning of nuclear facilities has been emphasized constantly from the point of view of IAEA’s safety standards. It is also known that IAEA will prepare the safety requirement on decommissioning of facilities; its title is the Safe Decommissioning of Facilities, General Safety Requirement Part 6. According to the result of IAEA’s Integrated Regulatory Review Service (IRRS) mission to Korea in 2011, it was recommended that the regulatory framework should require decommissioning plans for nuclear installations to be constructed and operated and these plans should be updated periodically. In addition, after the Fukushima nuclear disaster in Japan in March of 2011, preparedness for early decommissioning caused by an unexpected severe accident became important issues and concerns. In this respect, it is acknowledged that the regulatory framework for decommissioning of nuclear facilities in Korea need to be improved. First of all, we focus on identifying the current status and relevant issues of regulatory framework for decommissioning of nuclear power plants compared to the IAEA’s safety standards in order to achieve our goal. And then the plan is established for improvement of regulatory framework for decommissioning of nuclear power plants in Korea. It is expected that if the things will go forward as planned, the revised regulatory framework for decommissioning could enhance the safety regime on the decommissioning of nuclear power plants in Korea in light of international standards.


2019 ◽  
Vol 61 (3) ◽  
pp. 352-364 ◽  
Author(s):  
A. A. Ekidin ◽  
K. L. Antonov ◽  
M. E. Vasyanovich ◽  
I. A. Kapustin ◽  
I. Yu. Filatov

2016 ◽  
pp. 44-50
Author(s):  
V. Shestopalov ◽  
Iu. Shybetskyi

The paper considers evidences and mechanisms of potential impact of local depression (microgeodynamic) zones on NPP safety. The depression forms were revealed within the Chornobyl NPP site, including location of the new safe confinement. Nature of zones and character of their influence is determined by fault structures and conjugated deep degassing processes, which cannot be detected and studied by traditional methods of engineering and exploration works during NPP siting. The assumption was made that significant and still unexplored risks for nuclear facilities are related to probable release of deep hydrogen through the bottom of depressions along sub-bottom channels. The approaches were proposed to studying the system of “depression with its sub-bottom channel” within the sites of Chornobyl NPP and other nuclear power plants.


2021 ◽  
Vol 20 ◽  
pp. 96-105
Author(s):  
V. S. Havrylenko ◽  
◽  
I. V. Kutsyna ◽  
D. I. Кhvalin ◽  
◽  
...  

The year 2020 has become a real challenge for almost all aspects of life all over the world. Under these conditions, Ukrainian science, which has been in a state of crisis for more than a year, has been forced to overcome additional difficulties. However, due to the efforts of scientists, scientific work not only did not stop, but also received a large development effort in new directions and formats. In 2020, the Institute for Safety Problems of Nuclear Power Plants was one of the scientific institutions that under the new conditions made every effort to carry out the planned scientific researches and perform works in accordance with its activities. The main results of scientific and scientific-organizational activities of the Institute for Safety Problems of Nuclear Power Plants in 2020 are presented in the article. Despite the difficult economic situation due to the epidemic, the staff of the Institute obtained important results in studies of nuclear and radiation safety of the Shelter object, and in works aimed at improving the reliability and safety of existing Ukrainian and foreign nuclear power plants. The results of works in the field of the Shelter object transformation into an ecologically safe system, safe operation of nuclear facilities, decommissioning of nuclear facilities, spent nuclear fuel and radioactive waste management are presented in the article. The results of the work performed under the International Atomic Energy Agency (IAEA) grant and the Ukrainian-Japanese Science and Technology Research Partnership for Sustainable Development (SATREPS) project are described. The implementation of the results of these studies in practice is indicated. Scientific and expert activities in the interests and at the request of public authorities, cooperation with national and foreign scientific organizations as well as scientific and organizational activities in 2020 are described. Information on internal certification of employees, participation in international and national events, publishing and etc. is presented.


Author(s):  
Josef Podlaha ◽  
Karel Svoboda ◽  
Eduard Hansli´k

After more than 55 years of activities of the Nuclear Research Institute Rez (NRI) in the nuclear field, there are some obsolete nuclear facilities that shall be decommissioned. NRI is a leading institution in all areas of nuclear R&D in the Czech Republic. NRI has had a dominant position in the nuclear programme since it was established in 1955 as a state-owned research organization and it has developed to its current status. In December 1992, NRI has been transformed into a joint-stock company. The Institute’s activity encompasses nuclear physics, chemistry, nuclear power, experiments at the research reactor and many other topics. Main issues addressed in NRI in the past decades were concentrated on research, development and services provided to the nuclear power plants operating VVER reactors, development of chemical technologies for fuel cycle and irradiation services to research and development in the industrial sector, agriculture, food processing and medicine. The NRI operates two research nuclear reactors, many facilities as a hot cell facility, research laboratories, technology for radioactive waste (RAW) management, radionuclide irradiators, an electron accelerator, etc. The obsolete facilities to be decommissioned comprise various research facilities and facilities for RAW management. Decommissioning of nuclear facilities NRI is the only ongoing decommissioning project in the Czech Republic. Decommissioning started in 2003 and will be finished in 2014. Some facilities have already been successfully decommissioned.


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