Nuclear Power Plants Safety and Maintenance

Korea has been achieving the world best safety and economic performance of nuclear power plants through continuous technology development and asset management optimization since its first nuclear power reactor was introduced in the late 1970s. While most countries have stopped building new nuclear power plants since the severe accident in TMI nuclear plant in 1979, Korea has been steadily developing its own reactor models and constructing new nuclear plants. In addition, Korea won recent new nuclear plant project of United Arab Emirates (UAE) as a result of these efforts. A nuclear power plant consists of a great variety of complex equipment having state-of-the-art technologies, and the highest nuclear safety and equipment reliability are required. Therefore, the most sophisticated systematic engineering asset management is essential to the nuclear power plant. As a responsible company of operating and constructing all nuclear power plants in Korea, Korea Hydro and Nuclear Power Co. (KHNP) has developed its own asset management model for the nuclear power plants in operation and expanded the model into the new plants under construction. Since the asset management model was developed for the various equipment types in the nuclear power plant, it can be easily utilized in other industries as a highly effective asset management model. This paper presents new and innovative methods to refine and improve existing asset management practices in general plants by diagnosing KHNP’s physical asset management model. It contributes to the development and improvement of an advanced asset management model for general plant industries and utilities to meet the objectives of securing a clean environment, improved public health and safety, and general community well being.

Further increase of the reliability and efficiency of the operation of nuclear power plants depends on the comprehensive solution of many problems, of which the problem of optimization and increase of the informativeness of chemicotechnological monitoring is gaining in importance. There is a clear rift between the level of scientific ideas and technical solutions on which nuclear power plants are based and the existing approach to the organization of chemical monitoring. Everyone understands the necessity of chemical monitoring, but many people do not regard it as a necessary element for ensuring normal operation of a nuclear power plant. The lack of standard requirements and a standard methodical base markedly lowers the reliability of the results of analyses, and behind this lies possible breakdowns of the water-chemical conditions. How can this situation be explained? The consequences of deviations of water-chemical conditions from regulation standards are by no means manifested immediately. Apparent wellbeing at any given time creates the impression that the requirements of the chemical laws can be ignored with impunity. But there is also another reason for the disdainful attitude toward chemical monitoring. Chemical-technological monitoring at a nuclear power plant reduces to the determination of ~20 water-quality indicators for the basic and auxiliary systems. Considering the number of existing points at which samples are extracted in each block of a nuclear power plant and the frequency with which the analyses are performed, it is not difficult to imagine the impressive number of the overall volume of data obtained. Thus the total number of analyses per month for one block of a nuclear power plant with RBMK-1000 approaches 15,000 [i]. In addition, as a rule, these are single measurements, whose error it is virtually impossible to estimate exactly. Moreover, regardless of how conscientious the chemists-analysts at the technological laboratories are, in the monotony of repeating values it is difficult to escape big blunders in the case of unforeseen deviations of the parameters in the water-chemical conditions. Under these conditions there is no hope of obtaining reliable information for each of the measurements, making sense of the observational results, and drawing correct conclusions. We arrive at a p~r~dox, By increasing the number of parameters monitored and the number of points at which samples are extracted we strive to increase the information content of chemical monitoring, but we actually achieve the opposite result. At the present time, when nuclear power has transformed from a unique source of energy to one of the most important elements of the power production in the country, it is essential to reexamine the concepts forming the basis for the implementation of chemical-analytical monitoring at nuclear power plants. At the first nuclear power plants the research and technological functions of analytical monitoring were balanced, and preference was often given to obtaining research information. For serially produced nuclear power plants research programs are a rare episode. It is evident that the main reason for this situation is hidden in the existing standards and requirements imposed on the chemical monitoring system at nuclear power plants. At the first stages of development of nuclear power the striving toward performing as much analysis as possible and over the entire technolgocial loop was justified, whereas at the present time, as experience in operating nuclear power plants in this country and abroad shows, the time has come to search for new approaches to the problem of analytical monitoring of the quality of water heat carriers. The successful solution of the problem of analytical monitoring is often linked primarily with the instrumentation. But the number of methodical and instrumentation developments continues to increase, and the chemical-technological monitoring remains as before one of the laborious and unreliable elements in the overall chain of operational monitoring of nuclear power plants. Fundamental restructuring of the overall scheme of such monitoring is possible only based on automatic or, at least, automated means of chemical analysis.

Nuclear power plants (NPP) are subject to stiff requirements as to the cost effectiveness of their operation. However, since the NPP operation may be associated with the occurrence of severe environmental, social, political, material and other consequences as the result of nuclear and radiological accidents at NPPs, ensuring the specified level of the NPP safety is an operational task of the utmost importance. The current practice of the NPP design and operation suggests that the objectives involved in improving the efficiency of operation and those of ensuring the NPP safety level required by federal standards and regulations (NP-001) are achieved in isolation: no issues of ensuring high efficiency of the NPP operation are taken into account when addressing the issues involved in ensuring the safety of the NPP and, vice versa, it is a priori assumed that the required level of safety is ensured at any time when high efficiency of operation is achieved. The reason for this is the absence of procedures that make it possible to assess, in an integrated manner, the interdependence of economic and technological factors. The paper describes some of the methods to raise the efficiency of the NPP operation by selecting the best possible NPP maintenance and repair (M&R) strategies leading to high utilization and capacity factor values. A distinctive feature of the proposed techniques is that the efficiency of the NPP operation is proposed to be improved while ensuring at the same time the required level of the NPP safety with any NPP configuration.

With the development of civilization and the growth of the world’s population, the need for electricity also increases. Today, the main electricity sources are nuclear power plants (NPPs) and hydroelectric power plants (HPPs) that run on hydrocarbon fuels such as coal, peat, gas, and fuel oil. But these generating electricity methods have serious drawbacks, for example, the depletion of hydrocarbon natural resources, which leads to their shortage and rise in price. Nuclear and hydroelectric power plants cannot fully cover the need for electricity. In addition, the tragic events in the history of nuclear energy, e.g., the accident at the Chernobyl nuclear power plant, the nuclear power plant disaster in the city of Fukushima, etc., show great risks associated with the operation of nuclear power plants. Thus, solar energy engineering is the most efficient type of alternative, safe energy in the foreseeable future of mankind. This review is an effort to highlight the major progress and future challenges of using renewable energy sources.

The energy supply of the future in the EU will be a mix of renewable, fossil and nuclear. There are 145 nuclear power reactors in operation in 15 out of the 27 EU countries, with installed power ∼132 GWe. The age distribution of current nuclear power plants in EU is such that in 2010 most of them will have passed 20-years and approximately 25% of them 30 years of age. The decrease of energy supply from nuclear generated electricity can not always be compensated in a reliable and economical way within a short time span. For this situation utilities may be keen to upgrade the reactor output and /or to ask their regulatory bodies for longer term operation. Under the research financed in the Euratom part of the Research Directorate (RTD) of the European Commission several projects explicitly address the safe long term operation of nuclear power plants (NULIFE, LONGLIFE) and the topics proposed in the 2010 call explicitly address issues concerning component ageing, in particular non metallic components, i.e. instrumentation and cables (I&C) and concrete ageing. This paper presents an overview of the plans for long term operation (LTO) of nuclear power plants in the EU. Special emphasis is given on research activities on component ageing management and long term operation issues related to safety.

Objective To explore the personality features of nuclear power plant operators and the influencing factors thereof. Methods Minnesota Multiphasie Personality Inventory was used to examine the personality features of 136 nuclear power plant operators randomly selected from 2 cooperative units, all males. The results were compared with the nationwide norms and subsequently an inter-block contrast analysis was carried out. Results Obvious difference was observed in the final scores between the nuclear power plant operators and nationwide norms. The former got higher scores on hysteria （t=3.05, P〈0.05）, and lower scores on hypoehondriasis, depression, morbid personality, masculinity-femininity, paranoia, psychasthenia, schizophrenia, hypomania, and social introversion （t=7.47,7.47,7.31,2.23, 15.09,16. 15,19.28,7.88,11.10 ,P〈0.05 ）. The scores on hypochondriasis, depression, schizophrenia, and social introversion of those with the length of services over 3 years were all significantly higher than those of with the length of services less than 3 years （t= 3.25,2.51,2.76,3.00, P〈0.05 ）. The scores on hypoehondriasis, depression, psych0pathiedeviate, and social introversion of the operators aged over 30 were all significantly higher than those of the operators aged below 30 （t= 2.36,2.35,2.01,2.54,P〈0.05）. Conclusions The psychological quality of the nuclear power plant operators is superior to that of the general population. Key words: Nuclear power plant operators; Minnesota Multiphasic Personality Inventory; Personality; Psychological intervention

One of America’s best kept secrets is the success of its nuclear electric power industry. This paper presents data which support the construction and operating successes enjoyed by energy companies that operate nuclear power plants in the US. The result—the US nuclear industry is alive and well. Perhaps it’s time to start anew the building of nuclear power plants. Let’s take the wraps off the major successes achieved in the nuclear power industry. Over 20% of the electricity generated in the United States comes from nuclear power plants. An adequate, reliable supply of reasonably priced electric energy is not a consequence of an expanding economy and gross national product; it is an absolute necessity before such expansion can occur. It is hard to imagine any aspect of our business or personal lives not, in some way, dependent upon electricity. All over the world (in over 30 countries) nuclear power is a low-cost, secure, safe, dependable, and environmentally friendly form of electric power generation. Nuclear plants in these countries are built in six to eight years using technology developed in the US, with good performance and safety records. This treatise addresses the success experienced by the US nuclear industry over the last 40 years, and makes the case that this reliable, cost-competitive source of electric power can help support the economic engine of the country and help prevent experiences like the recent crises in California and the Northeast. Traditionally, the evaluation of electric power generation facility performance has focused on the ability of plants to produce at design capacity for high percentages of the time. Successful operation of nuclear facilities is determined by examining capacity or load factors. Load factor is the percentage of design generating capacity that a power plant actually produces over the course of a year’s operation. This paper makes the case that these operating performance indicators warrant renewed consideration of the nuclear option. Usage of electricity in the US now approaches total generating capacity. The Nuclear Regulatory Commission has pre-approved construction and operating licenses for several nuclear plant designs. State public service commissions are beginning to understand that dramatic reform is required. The economy is recovering and inflation is minimal. It’s time, once more, to turn to the safe, reliable, environmentally friendly nuclear power alternative.

ABSTRACTOperational radioactive waste is generated during routine operation of nuclear power plants (NPP). This waste must be solidified in order to ensure safe conditions of storage and disposal. Vitrification of NPP operational waste is a relative new solidification option being developed for last years. The vitrification technology comprises a few stages, starting with evaporation of excess water from liquid radioactive waste, followed by batch preparation, glass melting, and ending with vitrified waste blocks and some relative small amounts of secondary waste. Application of induction high frequency cold crucible type melters facilitates the melting process and significantly reduces the generation of secondary waste. Two types of glasses were designed in order to vitrify operational waste depending on the reactor type at the NPP. For the NPP with RBMK-type reactors the glass 16.2Na2O 0.5K2O 15.5CaO 2.5 Al2O3 1.7Fe2O3 7.5B2O3 48.2SiO2 1.1 Na2SO4 1.2NaCl (5.7 others) was produced. For NPP with WWER reactors the glass 24.0Na2O 1.9K2O 6.2CaO 4.3Al2O3 1.8Fe2O3 9.0B2O3 46.8SiO2 0.8Na2SO4 0.9NaCl (4.3 others) was produced. The melting temperatures of both glass formulations were 1200–1250 C, specific power consumption was 5.2 ± 0.8 kW h/kg, 137Cs loss was within the range 3 - 4 %. The specific radioactivity of glass reached 7.0 MBq/kg. Glass blocks obtained were studied both in laboratory and field conditions. Long-term studies revealed that vitrified NPP operational waste has the minimal impact onto environment. Since the glass has excellent resistance to corrosion it gives the basic possibility of maximal simplification of engineered barrier systems in a disposal facility. The simplest disposal option for vitrified NPP waste is to locate the packages directly into earthen trenches provided the host rock has the necessary sorption and confinement properties.

Objective To explore the correlation of the anti-stress ability of nuclear power plant operators with their heart rate,blood pressure and mental health.Methods A total of 136 male nuclear power plant operators received the continuous performance test (CPT) and mental health test (MHT),while 37 male senior students were used as the control group.Heart rate and blood pressure were recorded before and after the test.The nuclear power plant operators were divided to high score group and low score group by CPT scores.The correlation of the anti-stress ability and blood pressure,heart rate and their mental health was analyzedd.Results The scores of CPT and MHT test with the operators were significantly higher than those of the control group(t =- 1.25,6.25,P ＜ 0.05).After the test,the heart rate,systolic pressure and diastolic pressure of the operators were all significantly lower than those of the control group ( t =- 2.07,3.28,2.74,P ＜ 0.05 ).The CPT score of the high score group was lower in the heart rate,systolic pressure and diastolic pressure than the low score group(t=-3.15, -2.78, -2.54,P ＜0.05),while the scores of CPT and MHT were better(t =0.63,6.90,P ＜ 0.05).CPT scores were negatively correlated with the increasing range of the heart rate,systolic pressure and diastolic pressure( r =- 0.69,- 0.94,and - 0.62,P ＜ 0.05 ),and positively correlated with the MHT scores ( r =0.54,P ＜ 0.05 ).Conclusions To a certain extent,CPT and MHT test can reflect the anti-stress ability and be used as one of the bases to select nuclear power plant operators and to assess their competence. Key words: Nuclear power plant operators; Anti-stress ability; Blood pressure; Heart rate; Mental health

As of January 2013, the U.S. Nuclear Regulatory Commission (NRC) has renewed the operating licenses of 73 nuclear units out of a total of 104 licensed units, allowing for up to 60 years of safe operation. In addition, the NRC has license renewal applications under review for 15 units and more than 13 additional units have announced plans to submit applications over the next few years [1]. This brings the total of renewed licenses and plans for renewal to over 97% of the 104 operating nuclear units in the U.S. This paper presents the status of the U.S. license renewal process and issues being raised for possible applications for subsequent renewals for up to 80 years of operation. By the end of 2013 there will be 26 nuclear plants in the U.S. (or 25% of the 104 units) that will be eligible to seek a second license renewal and by the end of 2016 this number will increase to about 50% of the 104 licensed units. Although some nuclear plant owners have announced plans to shutdown before reaching 60 years, the majority are keeping the option open for long term operation beyond 60 years. The factors that impact decisions for both the first license renewals and subsequent renewals for 80 years of safe operation are presented and discussed in this paper.

Power transformer is one of the most important electrical equipment for safe and reliable operation of Nuclear Power Plant. For trouble free operation of transformer, it is necessary to monitor its health during the lifecycle. There are clear needs for the development of prognostics and health management techniques so that smooth operation of transformer as well as safe operation of nuclear power plant can be ensured. This paper focuses on transformer asset management using Health Index approach. According to actual available data from a nuclear power plant, this paper revises the referenced HI model (Kinectrics Inc.) to consider actual test results of transformer performed in the field, dissolved gas analysis and other test of oil, maintenance work orders on various components of transformer, health of tap changer etc. The final value of health index is associated with the predicted life and condition of transformer according to pre-defined limits. Revised health index model studied is tested by the actual test data collected from a real nuclear power plant. It shows that the improved method is practically feasible for nuclear power plant. Introduction, revised health index model, results, discussion and recommendations are described in detail in following sections.

VERLIFE – “Unified Procedure for Lifetime Assessment of Components and Piping in WWER NPPs during Operation” was initiated and co-ordinated by the Czech and was developed within the 5th Framework Program of the European Union in 2003 and later upgraded within the 6th Framework Program “COVERS – Safety of WWER NPPs” of the European Union in 2008. This Procedure had to fill the gap in original Soviet/Russian Codes and Rules for Nuclear Power Plants (NPPs) with WWER (Water-Water-Energetic-Reactor = PWR type) type reactors, as those codes were developed only for design and manufacture and were not changed since their second edition in 1989. VERLIFE Procedure is based on these Russian codes but incorporates also new developments in research, mainly in fracture mechanics, and also some principal approaches used in PWR codes. Last upgrading and principal extending of this VERLIFE Procedure was realized within the 3-years IAEA project (in close co-operation with another project of the 6th Framework Program of the European Union “NULIFE – Plant Life Management of NPPs”) that started in 2009 with final approval and editing in 2013. As all versions of the VERLIFE procedure were coordinated by the Czech and first version was based on the Czech version of the NTD ASI, there have been simultaneously incorporated into the Czech NTD ASI (Normative Technical Documentation of the Czech Association of Mechanical Engineers) guidelines that are accepted by the Czech State Office for Nuclear Safety for the use in evaluation of Czech NPPs. This document has several parts: Section IV – “Evaluation of Residual Lifetime of Components and Piping in WWER type NPPs” deals with the evaluation during NPP operation. Main part of the document is divided into four main parts: - Evaluation of resistance of components and piping against non-ductile failure - Evaluation of resistance of component and piping against fatigue damage, - Evaluation of resistance of components and piping against corrosion-mechanical damage - Evaluation of residual lifetime of components and piping with defects found during in-service inspections Additionally, several appendices are included for detailed description of individual parts of evaluation, e.g. - Determination of neutron fluences in reactor pressure vessel and internals - Determination of degradation of materials during operation - Requirements for evaluation of pressurized thermal shock regimes - Evaluation of corrosion-errosion effects in piping - Environmental fatigue evaluation - Evaluation of reactor pressure vessel failure probability Finally, the following appendices dealing with components integrity have been included: - Lifetime of reactor pressure vessel internals - Leak-before-break concept for WWER piping - No-break-zone for WWER piping The paper will describe structure and main principles of this Section IV.

The increasingly severe climate conditions are not only bringing harmful effects on human survival and development, but also causing serious challenges to the safety application of nuclear power technology. There have been many operation incidents where extreme climate hazards affected the safe and stable operation of nuclear power plants (NPPs) worldwide. Humanity is entering an unknown territory of global climate damage, with the frequent occurrence of extreme climate disasters caused by greenhouse gas emissions, the impact of extreme climate hazards on the development of nuclear power technology application will become increasingly prominent. Based on the national energy development strategies and the relevant technical policies for nuclear power technology application, combined with the current development status of the commercial NPPs in China, an analysis was made on the interdependent relationship between extreme climate change and nuclear power technology development. On the analysis of the requirements of the national nuclear safety regulations, guidelines and standards, this paper analyzed the potential impacts of the external hazards caused by extreme climate change on the safe and stable operation of NPPs, discussed the current status of the protection design and the protection capabilities of the operating and constructing NPPs against extreme climate hazards in China. On this basis, this paper analyzed the future development directions of the protection against extreme climate hazards for nuclear power technology application in China, so as to effectively adapt to the possible impacts of the future extreme climate change on the safety application of nuclear power technology.

Objective To investigate the attitude toward and perception of the risk of nuclear power plant among the public residing in vicinity of nuclear power plant,as well as the related factors.Methods A face-to-face interview on perceived radiation risks was conducted among 1408 individuals in Liangyungang City, Jiangsu Province.where the Tianwan nuclear power plant was under construction.The four groups was defined according to the distance between the residence of the subjects and the Tianwan nuclear power plant:<4 km,4- 8 km,8-30 km and 30-50 km.A was used to collect information on education,working history,religion, perception of major industries hazards especially nuclear power plant,and major factors may influence their perceptions.Ordinal logistic regression model was used to analyze the data.Results About 91.18% of the interviewee heard about the nuclear power plant,35.36% of them had knowledge about Chernobyl nuclear power plant accident,71.05% of them believed that the nuclear power plant had no negative effects on environments, 37.03% of them believed that the nuclear energy was safe.74.27% of them believed that it was necessary for China to develop nuclear energy.63.29% of them supported the construction of the nuclear power plant in local area.Ordinal logistic regression analysis revealed that the higher education,higher family annual income,male, economic benefits from the nuclear power plant construction,and trust in local government having competency to handling emergencies were positive factors;otherwise,impression on nuclear power plant of bad influences on environment and health were negative factors.An inverted U-shaped with a right tailing relationship between negative attitudes toward nuclear power plant and distance to the plant was found.Conclusions Education, gender,family annual income and expectation of economic benefit returns were the major factors influencing the perception of and attitudes toward nuclear power plant.More works needed to be done to mitigate the negative attitude of the residents in vicinity of nuclear power plant and enhance the public acceptability . Key words: Nuclear power plant; Radiation; Risk; Public perception

Recently, interest in nuclear power has surged. Several countries are either planning for or have already begun constructing new nuclear power plants. The European Union now includes nuclear in its green taxonomy (EU 2022/1214). Coupled with recent technical development, most notably 4th generation- and Small Modular Reactor technology, there are even talks of a renaissance of nuclear power.In Sweden, this phenomenon has manifested in plans to again build nuclear power plants. The government has launched a new nuclear program (Busch et al, 2023), laws are being changed (Andersson, 2023) and investigations are ongoing to facilitate the financing of new power plants (Dillén, 2024).In the past, Sweden was at the forefront of civil nuclear technology by building twelve reactors between 1971 and 1985 (IAEA, 2021). Thereafter followed, however, a period of decommissioning where six reactors were phased out (ibid, 2021). With recent plans to build new nuclear plants, Sweden has once again changed paths.According to theoretical insights of sociotechnical imaginaries (STI) this development can be understood as informed by visions of how nuclear power will aid in achieving a beneficial future (Jasanoff &amp; Kim, 2015; 2009). Within this field of research, several papers have studied different nations’ constructions of (un)desirable futures of nuclear power (e.g., Felt, 2015; Jasanoff &amp; Kim, 2009). Hence, an approach informed by STIs is adopted to study the Swedish turn towards building new nuclear power.Interestingly, many of the arguments for new nuclear power in Sweden evoke its history. Sweden is described as a pioneer in nuclear energy with extensive experience and a high level of skills in science and engineering. This act of evoking the past to describe the future highlights the complex temporalities involved in the establishment of STIs. Past experiences are recalled in the present and used to inform how the future is envisioned (c.f. nuclear memory, Keating &amp; Storm, 2023), hence, creating an intrinsic entanglement of temporalities partly studied (e.g., Samimian-Darash et al, 2024), but more research into this entanglement is needed.Furthermore, as suggested by Hughes (2024), previous studies have not considered enough the extent to which emotions and affect aid in the forming of STIs. Due to the discursive nature of STIs they tend to be studied through policy documents, thus missing the embodied feelings involved in their enactment (ibid, 2024). Therefore, this study mainly relies on interviews with prominent individuals and experts in nuclear power (N=39), in addition to the analysis of newspapers and other written documentation.The result highlights how the evocation of nostalgia is central to the Swedish turn towards new nuclear power. Hence, also showing how the formulation of the STI is equally concerned with envisioning the past as with envisioning the future. The paper contributes to the general research on STIs, especially ongoing discussions on its intertwined temporalities and affective and emotional dimensions, as well as providing empirical insights on new nuclear power in Sweden.