Construction Of Nuclear Power Plants Research Articles

FIELD AND MODEL RESEARCH OF THE GROUNDWATER FLOWS IN THE AREA OF THE PAKS-2 NPP CONSTRUCTION, HUNGARY

The construction of the nuclear power plant (NPP) requires conducting a large number of engineering and hydrogeological surveys, as well as assessment of the design decisions’ safety. A deep excavation pit at the Paks II NPP construction site requires execution of the cut-off wall due to extremely high groundwater saturation of the alluvial deposits. However, lithological anisotropy and the presence of dislocation zones did not allow identifying the appropriate depth for the cut-off wall construction. Unfortunately, engineering geological boreholes with a 20-meter distance between them and surface and borehole geophysical surveys could not identify the hydrogeological units. Thus, to conceptualize the hydrogeological settings, an analysis of the groundwater head distribution and the large-scale pumping tests were conducted. The interpretation of the geological data and the distinguishing of the hydrogeological units were carried out iteratively using the hydrogeological numerical model. The flow model could represent the hydraulic head distribution, the response of the lithologically heterogeneous layers to the water fluctuations in the Danube river, and the pumping tests carried out at the different depths. The results of the hydrogeological modeling revealed the aquitard to be continuous throughout the territory; however, its top’s depth changes from 30–35 to 90 m within the construction site of the Paks II NPP. This complex geometry of the aquitard is controlled by the plicated dislocation zone, which cuts the construction site in half and is revealed as the right wall of the graben.Correct hydrogeological stratification enabled us to ensure waterproof activities such as the cut-off wall construction using the hydrogeological model when excavating a deep pit for the Paks II NPP. This also minimizes the hydrodynamic impact on the closely located NPP Paks in operation.

The anthropogenic effects on organic matter in sediment core based on Bayesian mixing model: a case study of Daya Bay.

Sediment is an important carrier of evidence about environmental evolution which receives huge volumes of organic material originated from both anthropogenic and natural sources. In this study, based on sedimentary chronology, the vertical trends of particle size distribution, total organic carbon (TOC), total nitrogen (TN), and their stable isotopes (δ13C, δ15N) in the sediment core of the nuclear power sea in southwest Daya Bay were analyzed, and the distribution characteristics and contribution ratios of different sources of organic matter in the sedimentary environment over the past 70years were resolved using a Bayesian mixing model (MixSIAR). TOC, TN, δ13C, and δ15N ranged from 0.89 to 1.56%, 0.09 to 0.2%, - 22.3 to - 20.6‰, and 4.38 to 6.51‰, respectively. The organic matter in the sediment is controlled by a mixture of terrestrial input and marine autochthonous, the proportion of organic matter from terrestrial sources increases, while that from marine sources decreases in the sediment core, which persists from 1960 to 2000, yet organic matter from marine sources still dominates. The first signs of increased primary productivity occurred in 1960, and it was primarily due to agricultural activity. After the 1980s, the rapid increase in population around Daya Bay, the construction of nuclear power plants, the rise of aquaculture, and the quick expansion of industrial bases were all major factors that changed the ecological environment of Daya Bay.

Experimental investigation of gamma radiation shielding ability of some building materials in Bitlis (Turkey)

Considering that people spend most of their time in buildings (home, office, school, shopping mall, etc.), it is seen that the radiation retention properties of building materials are important. Nuclear power plants are a complex of structures that are of great importance in today's energy-age world, but also bring some dangers. The most important of these dangers is the possibility of radiation leakage from these structures in the event of an explosion. In addition, shielding for radiation protection is important in medical applications and industry where radiation is widely used. Therefore, the strength and durability properties of concretes to be used in the construction of nuclear power plants need to be meticulously designed. All this shows how important and worthy of research the subject of the study is. For this purpose, new materials that are easy to access, abundant and cheap, and have high absorption capability are needed, rather than shield made only of lead materials. Perlite, pumice and Ahlat stones are abundant in Bitlis (Turkey) province and are extracted from the quarries. The bims block samples (B-1, B-2 and B-3) produced in factories in Bitlis. This study was carried out to investigate whether these materials, which are used as building materials, have radiation absorbing properties in terms of their use in different areas. Linear attenuation coefficients were calculated experimentally for gamma energies at 88.04 ± 0.01 keV, 356.50 keV, 661.60 keV, 834.80 ± 0.04 keV and 1173.20–1332.50 keV (for 109Cd, 133Ba, 137Cs, 54Mn and 60Co radioactive point sources) using gamma spectrometry with a NaI scintillation detector. In addition, photon absorption percentages, half value layer (HVL), tenth value layer (TVL) and mean free path (MFP) values of the samples were calculated. The obtained data were evaluated by comparing with similar studies in this field and the results obtained for lead shield. As a result of the study, it is seen that instead of using perlite and pumice alone, it is better radiation trap when they are mixed with each other and formed into bims blocks.

Critical review of nuclear power plant carbon emissions

Nuclear power plays a crucial role in achieving the target of carbon neutrality to build a sustainable society. However, it is not “carbon-free” when considering its entire life cycle. Therefore, accurate accounting and monitoring of its generated carbon emissions are required to avoid miscalculations of nuclear energy as a clean energy source. In this study, the life-cycle carbon emissions of nuclear power plants (NPPs) with different reactor types are reviewed. In addition to the characteristic differences among different reactors, disparities in the review results originate from the varying emissions at the respective stages of the nuclear fuel cycle, technology choices at each stage and accounting methods and boundaries. The carbon emissions resulting from NPP construction and operation are underestimated due to the limited data and methods, which creates uncertainty in the evaluation of NPP carbon emissions. An integrated framework for carbon emissions accounting considering the construction and operation of NPPs (CACO-NPP) is proposed. This integrated framework aims to improve the accounting accuracy for carbon emissions originating from NPPs. An emerging Generation III NPP with the latest technology, HPR1000 (an advanced pressurized water reactor), was adopted as a case study. The results show that the total emissions resulting from vegetation loss, equipment manufacturing and labor input during construction and operation are 1232.91 Gg CO2 with a carbon intensity of 1.31 g CO2/kWh, indicating the notable mitigation capability of Generation III NPPs. By combining the maturity of HPR1000 technology with successive design improvements, the carbon emissions of such reactor types could be further reduced. This development is very important for realizing China’s carbon neutrality target.

Breaking the Myth of Nuclear Power Omnipotence in the Cold War era: Discourse on Nuclear Power and the Movement against the Construction of Nuclear Power Plants in South Korea in the 1980s and early 1990s

In South Korea, the frontline of the Cold War in East Asia, an active anti-nuclear movement could not emerge until the 1970s due to the effects of Korean War, national division, and the Cold War culture. In the 1970s, youth activists, religious figures, and intellectuals who opposed the military regime became concerned about environmental issues as a reaction to the adverse effects of industrialization pursued by the military. In the 1980s, the ecological movement gave way to the anti-nuclear peace movement, which confronted the security discourse that dominated the Cold War era. The South Korean democratization movement of the 1980s overcame and transcended Cold War factionalism on an ideological level, and as a result, anti-nuclear peace activists opposed the nuclear disarmament of the Korean Peninsula and called for the abolition of nuclear power plants. Based on anti-foreign nationalism, they used a discourse that directly linked individual life, safety, and health rights to national survival and peace, and treated nuclear weapons as a symbol of imperialist oppression.</br>Environmentalist organizations, such as the ‘Anti-Pollution Movement Association’, actively engaged in solidarity activities with local residents' protests against the construction of nuclear power plants and nuclear waste sites. As the case of Yeonggwang-gun, Jeollanam-do shows, the difference in position between the local residents who pursued economic compensation and the establishment of a sustainable basis for livelihood and the environmental movement group that pursued the public spread of the anti-nuclear movement led to distrust and conflict, despite the devoted solidarity of both sides. As the case of Anmyeonisland shows, conflicts between residents were intensified by monetary inducements from government organizations, undermining their everyday relationships. Nevertheless, the anti-nuclear movement in Korea from the late 1980s to the early 1990s contributed greatly to breaking the myth of nuclear power omnipotence in the Cold War era, revealing the ecological agenda to Korean society, and laying the foundation for the growth of the eco-environmental movement in the 1990s.

Method for solving atmospheric dispersion parameters of radioactive aerosols based on wind-tunnel laser measurement experiments

Certain fraction of radionuclides was inevitably discharged into the atmosphere during the normal operation of nuclear power plants. Therefore, the atmospheric dispersion of these airborne radioactive aerosols is an essential part of radiation environmental assessment during the siting, construction, and operation of nuclear power plants. Gaussian plume model is the most widely used method for this assessment. Evaluation uncertainty of this method mainly depends on the selection of atmospheric dispersion parameters. In this paper, the laser measurement method was carried out in the atmospheric wind-tunnel dispersion experiments of aerosols, and a method for solving atmospheric dispersion parameters based on high-resolution laser scattering images of plumes was proposed. Firstly, a full-frame statistical image of aerosol atmospheric plume trajectories was obtained through high-resolution laser measurement. Secondly, image processing was performed to remove noise, then to acquire light intensity of image pixels, and to make 95.45% (2σ) of the total light intensity fall within the plume trajectory to determine the plume boundary line at last. Finally, the atmospheric dispersion parameters were determined by optimal fitting, using the Gaussian plume model as a benchmark. Compared with the commonly used method for solving atmospheric dispersion parameters based on single-point densitometer detection experiments, the method based on laser measurement proposed in this work has advantages in reflecting directly realistic plume trajectory of both aerosols and particles with large sizes. This study can provide technical support for the accurate evaluation of aerosols or particles atmospheric dispersion.

Global Review of International Nuclear Waste Management

In the current situation of global energy transition, nuclear energy maintains its reputation as a stable power generation technology, without dependence on other resources and without CO2 emissions. However, one of the main problems with its use is the management of the radioactive waste it generates, which has given rise to different international strategies: (i) reprocessing; (ii) storage; and (iii) disposal. Given the interest generated by nuclear energy in recent times and the need to manage the waste generated, this paper presents a global review of the different international nuclear waste management strategies, using a scientific method based on (i) a bibliometric review of the scientific publications related to nuclear waste management and (ii) an analysis of the technical aspects of the different international management strategies. The effective and safe management of nuclear waste will contribute to the advancement of international nuclear energy development strategies that encourage the construction of new nuclear power plants and the lifetime extension of existing ones.

MAPPING OF S-WAVE ATTENUATION FIELD USING THE CODA ENVELOPES OF LOCAL EARTHQUAKES AND QUARRY BLASTS FOR THE EAST KAZAKHSTAN REGION ON THE DATA FROM PERMANENT AND TEMPORARY SEISMIC STATIONS

The paper considers the heterogeneities of short-period shear waves attenuation field in the east Kazakhstan lithosphere including the region of the Semipalatinsk Test Site where a lot of test detonations of nuclear weapons were performed underground in the past. The common S-waves coda envelopes were obtained by the records of near calibration explosions and quarry blasts as well as local earthquakes on the data from permanent and temporary stations. The obtained data allowed us to create attenuation field sections in the lithosphere of the considered region. The attenuation field heterogeneities were mapped for the lower crust and uppermost mantle of the east Kazakhstan. Very low Q-factor values (Qs~40–55) correspond to several stations installed in the area of the Balapan test site where the most powerful test explosions were conducted. These values are much lower than the minimum values corresponding to a large number of stations installed in seismically active region of the Northern Tien Shan. It is supposed that this is due to upwelling of deep-seated fluids along the active fault zones under a long-term intensive vibration effect. The obtained data can be used to reveal the zones having high concentration of fluids in the lithosphere parts of probable large earthquake generation. This information is quite important due to the planned construction of nuclear power plant in the east Kazakhstan region.

Nuclear Power Program in Turkey as a Nuclear Newcomer Country

Turkey's interest in pursuing a nuclear power program can be attributed to the necessity to meet the country's fast expanding electricity consumption while also assisting economic development. Turkey, as a nuclear newcomer country and a member of the global nonproliferation regime, has been interested in civilian nuclear technology since 1970s. Despite substantial development in domestic energy output, Turkey still relies heavily on imported energy. In this regard, diversification of resources to generate electricity presents significant importance for the country. 
 Akkuyu Nuclear Power Plant (NPP) project proposes a unique concept for the construction of the country's first NPP with its own model (BOO model). The paper examines Turkey's electricity demand, the motivations for pursuing nuclear energy, and the substance of the parties' intergovernmental agreement for the BOO madel. Finally, as a nuclear newcomer country, the significance of the Nuclear Regulatory Authority (NRA) in the framework of the domestic legal law and international nuclear law is emphasized.

DEVELOPMENT OF NUCLEAR ENERGY IN THE REPUBLIC OF KAZAKHSTAN: ISSUES AND TRENDS

Purpose of the research is to study the level of public awareness, transparency and trust in the authorities in the framework of the state policy for the construction of a nuclear power plant.Methodology. In this work, both qualitative and quantitative research methods are applied. The study uses an online sociological survey among the population to analyze the impact of the ongoing state policy on the energy security of the country, namely the construction of nuclear power plants. In this work, an online survey based on a Google Survey was used. The survey involved 108 respondents. Also presented in the work are information materials of state institutions, information and news articles, as well as a review of international experience in the field of nuclear energy. Also, for the analysis and evaluation of external factors for developing nuclear energy, we considered PEST-analysis (Political, Economic, Social, and Technological factors).Originality / value of the research. Society plays an important role in solving the most urgent and acute political issues in the country. The awareness and opinion of citizens contributes to the development in society of a positive attitude towards the political decisions made in the state. Over the past two decades, in some countries, policies to reduce energy costs and targets for reducing greenhouse gas emissions have contributed to the introduction of clean energy, including nuclear energy. In Kazakhstan, the issue of energy security has always been relevant and has never been removed from the agenda. Today, despite all the eff orts of the state, problems in the energy sector are not decreasing.Findings. This paper analyses the statements of many authors who believe that the degree of public awareness depends on the transparency and informational openness of state bodies. A sociological study was used in this work in order to empirically prove the influence of these factors. The survey contains the answers of the respondents. The analysis turned out to be quite interesting. As a result, the presence of a positive relationship between the level of information provided by state institutions and the awareness of citizens has been clearly demonstrated.

Molecular dynamics study on the adsorption of radioactive ions by geopolymers

The construction of nuclear power plants necessitates careful consideration of the discharge and fixation of nuclear waste. Geopolymers are new cement-based materials (CBMs) with three-dimensional cage-like structures that enable effective nuclear waste fixation. In this work, the adsorption of radioactive caesium and strontium ions by sodium aluminosilicate hydrate (NASH) gel, the main component of geopolymers, was investigated using molecular dynamics simulations to obtain nanoscale insights into the ions’ interactions with the gel. The formation of strong ion–oxygen bonds allowed both ions to be effectively adsorbed on the NASH surface, but the adsorption ratio of strontium ions (17.2%) was slightly lower than that of caesium ions (21.0%). Because strontium ions are divalent, they can form stronger electrostatic interactions with water molecules and chloride ions, which hinders their approach to the interface. For the same reason, the diffusion coefficient of strontium ions in solution is lower than that of caesium ions. These results provide new insights into the nuclear waste fixation capacity of NASH gel and guidance for the design of new CBMs for radioactive waste disposal.

Towards a zero-carbon nuclear energy future: a review

In order to attain a relatively zero-carbon future, nuclear energy is proposed to be one of the major solutions. In our quest to deal with climate change, we need to thirst for a clean energy source in the present day world of advancing technology. On each day, it is vivid that the demand for energy is increasing faster as compared to past years. The rate at which fossil fuels are being consumed may soon result in their extinction. Equipped with these facts, it is safe to turn to nuclear power as an alternative in order to attain a clean energy future. Therefore, this work tries to review how this can be a possibility knowing very well that nuclear energy has relatively low emissions of carbon dioxide as compared to other energy sources apart from hydroelectricity. In terms of greenhouse gasses, nuclear energy emits relatively lower amounts. This paper also highlights issues surrounding nuclear power plants construction as well as climate change effects, mitigation and adaptation. Safety issues of power plants which is a major concern by the public will also be tackled in brief.

Modelling Irradiation Effects in Metallic Materials Using the Crystal Plasticity Theory—A Review

The review starts by highlighting the significance of nuclear power plants in the contemporary world, especially its indispensable role in the global efforts to reduce CO2 emissions. Then, it describes the impact of irradiation on the microstructure and mechanical properties of reactor structural materials. The main part provides the reader with a thorough overview of crystal plasticity models developed to address the irradiation effects so far. All three groups of the most important materials are included. Namely, the Zr alloys used for fuel cladding, austenitic stainless steels used for reactor internals, and ferritic steels used for reactor pressure vessels. Other materials, especially those considered for construction of future fission and fusion nuclear power plants, are also mentioned. The review also pays special attention to ion implantation and instrumented nanoindentation which are common ways to substitute costly and time-consuming neutron irradiation campaigns.

What is the future of nuclear power in Ukraine? The role of war, techno-economic drivers, and safety considerations

The TIMES-Ukraine energy system model is used to explore the future of nuclear power plants (NPPs) under an ambitious climate policy scenario, achieving net zero greenhouse gas emissions in 2050. Varying techno-economic (construction costs and capacity factors for NPPs, capital costs for solar and wind), policy (ban on construction or extension of NPPs), and macroeconomic (alternative economic recovery trajectories) factors are considered. The difference in the techno-economic assumptions for nuclear power generation has a very moderate impact on the total system costs (TSC) of the energy transition, as their variation (positive or negative change) does not exceed 0.1%–0.2% relative to the default case. Policy decisions on restricting nuclear power generation could have a more substantial impact, as TSC increase by 4–5 billion USD (0.6%–0.9%) over the 2020–2050 period under the most restrictive case. In terms of the economic viability of various NPPs, we find small modular reactors to be more competitive than large NPPs due to the higher availability factor. Overall, in terms of developing new NPP capacities, policymakers can consider alternative futures for this technology without major implications for the energy transition costs, as retired NPPs can be substituted by alternative generation technologies in a cost-competitive manner.

Unique safety features and licensing requirements of the NuScale small modular reactor

Small modular reactors (SMR) offer a novel approach to the construction and operation of nuclear power plants. The NuScale VOYGR™ plant uses a simplified SMR design that is based on proven light-water reactor technology with substantial improvements in nuclear safety. It consists of a 250 MWt reactor core housed with other primary system components in an integral reactor pressure vessel surrounded by a steel containment vessel, all of which is immersed in a large pool of water that also serves as the ultimate heat sink. At the core of the NuScale safety case are three primary safety systems: the decay heat removal system, the emergency core cooling system, and the containment. The ability of the NuScale Power Module (NPM) passive safety systems to remove core decay heat for an unlimited duration is demonstrated through analysis of a beyond-design-basis extended loss of AC power with no replenishment of water to the ultimate heat sink or operator actions. The NuScale methodology to evaluate an indefinite loss of AC power uses the proprietary NRELAP5 systems analysis computer code. Analysis results show that the reactor coolant system liquid level above the core is maintained and that containment pressure remains below the vessel design pressure. Once full passive air cooling is established, containment pressure and temperature will decrease over time with decreasing core decay heat. NuScale received standard design approval in September 2020 and design certification in January 2023 for its 50 MWe NPM configured as a 12 module plant. NuScale is currently seeking standard design approval to increase its core power to 250 MWt, nominally 77 MWe per module, in a 6-module plant (VOYGR™-6) configuration. The high-level safety of NuScale’s SMR technology is foundational to a new standard of nuclear power plant resilience.

Impact of Temperature and Radiation Factors on Special Concretes Used for NPP Construction

The core catcher is arranged in an unattended, unventilated sub-reactor space. It is designed to receive molten corium in emergencies, and thus the concrete used in the core catcher must be resistant to high temperatures without significant loss of strength. During nuclear power plant (NPP) operation, these concretes are subjected to considerable radiation exposure, which may also affect their physical–chemical properties. Concrete mixes based on Portland cement and alumina cement with iron and corundum aggregate were investigated. Model samples of concrete were subjected to temperature exposure in the temperature range of 100 to 1000 °C and to radiation exposure in the field of mixed and neutron irradiation in the reactor cell at a load of at least 1 × 107 Gy. Concrete heating over 200 °C leads to a decrease in strength characteristics from 25.1 MPa to 2.6 MPa in Portland cement-based concretes and from 40 MPa to 12 MPa in alumina cement-based concretes. The decrease in concrete strength at high temperatures is due to dehydration of hardening phases, polymorphic transitions of aggregate and chemical interaction between concrete components. Radiation exposure of Portland cement-based concrete samples leads to an increase in their strength. Alumina cement-based concretes are less resistant to radiation exposure, and their strength decreases as a result of radiation exposure-induced processes.

Атомная энергетика как инструмент внешней политики России на Ближнем Востоке

Introduction. The article examines the development of the nuclear industry and the successes of the State Corporation “Rosatom” which allows Russia not only to ensure the growth of this important sector of industry and economy, but also to occupy a leading position in the world nuclear energy markets. In addition to the economic effect, this direction of state activity allows solving a wide range of foreign policy tasks. The article analyzes how the Russian state, using the potential of its nuclear industry and its competitive advantages, simultaneously realizes its interests in the Middle East. Methods and materials. During preparing the article, the authors used a synthesis of institutional and systemic approaches, a comparative historical approach, research in the development of diplomacy and the balance of “powers” in the foreign policy of the state, as well as predictive analysis within the problem field of the implementation of the foreign policy instrument under consideration. Analysis. At present, state corporation Rosatom is one of the leaders in the global nuclear industry and is implementing projects for the construction of 35 power units around the world, including the Middle East. Nuclear energy programs are currently planned or are under way in six countries in the region. Of the projects noted, Rosatom has firm agreements with Egypt, Iran and Turkey. Also, the Russian leadership is optimistic about the possibility of concluding contracts for the construction of nuclear power plants in Jordan and Saudi Arabia. The competitive advantages of a Russian company have a wide range from technological advantages to the most flexible terms of cooperation, regardless of the foreign policy and global conjuncture. At the same time, the activities of Rosatom are converted into political advantages that ensure the strengthening of Russia’s influence in the Middle East region. Discussion. The authors assess the further development of the Middle East programs for the development of the peaceful atom, Russia’s participation in these processes, as well as the identification of associated risks. Results. The authors conclude that by using and developing nuclear energy, Russia is promoting its national interests in the context of the continuing negative economic and political background in the world. The country’s leading positions in this industry make it possible to build favorable forecasts regarding the application of nuclear energy in the field of foreign policy, including the Middle East, where Russia has many competitive advantages. Authors’ contribution. D.A. Mirgorod developed the content of the article and carried out its scientific edition. E.F. Parubochaya analyzed cases related to the implementation by Russia of nuclear power plant projects in Iran and Turkey.

Влияние параметров дисперсного армирования на ползучесть высокопрочного сталефибробетона

Introduction. At the present time, in the construction of nuclear power plants (NPP), non-removable formwork made of high-strength steel fibre concrete (SFRC) is used. Due to improved physical and mechanical properties and high adhesion to monolithic concrete, the SFRC formwork is a load-bearing element. The result is a structure with combined reinforcement in the form of bar reinforcement and high-strength SRFC layers. The calculation of the actual stress-strain state of such structures requires knowing the design characteristics of used materials. High-strength SFRC is understudied material, and research of its properties, especially under long-term loads, is a crucial task. Materials and methods. Experimental studies of the effect of dispersion reinforcement parameters (type of steel fibre and its volume) on the creep value of SFRC made on a high-strength cement-sand matrix have been carried out. The research was carried out on the same matrix composition for three types of steel fibres suitable for the manufacture of 30 mm formwork sheets with a thickness of 30 mm, and most commonly found the in Russian market. A volumetric fibre content of up to 6 % was considered in the study. The load level is 0.3 of the breaking strength (prism strength). Results. The actual values of the SFRC creep parameters required to carry out the calculations of structures with combined reinforcement. Conclusions. It is found that the introduction of steel fiber up to 6 % provides a reduction of ultimate creep measure up to 20 % as compared to a fine-grained matrix. However, with up to 1.5 % volumetric content of fibre, an increase of up to 10 % in creep may also occur as a result of matrix decompaction. In the view of the large number of factors affecting the properties of SFRC, the calculated characteristics should be determined experimentally.

Effect of Magnetite Concrete on Splitting Tensile Strength and Gamma Ray Shielding Performance Exposed to Repeated Heating at High Temperature

Radiation shielding concrete is one of the most used materials in the construction of nuclear power plants and will be subjected to high temperatures for a long time during its service life. This study aims to investigate deterioration of radiation shielding concrete with multiple heating at different temperatures. A microwave oven was used as a heating apparatus to simulate irradiation, and 200, 300, and 400 °C were selected as experimental cycle temperatures. The apparent characteristics, mass loss, splitting tensile strength, and gamma ray shielding properties of the commonly used magnetite shielding concrete were investigated. The results showed that the splitting tensile strength and gamma shielding performance of concrete were dramatically reduced at first heating. Then, as the heating times increased, the splitting tensile strength and gamma shielding properties of the concrete continued to deteriorate, and the higher the increase in heating temperature, the more severe the deterioration of the concrete. During the service period of radiation shielded concrete, the magnitude of temperature under the service conditions will affect the deterioration degree of concrete, and the continuous change of temperature will continuously lead to the deterioration of concrete.

Performance of polypropelene and polyester fibres-reinforced reactive powder concretes at elevated temperatures

Reactive Powder Concrete (RPC) is an emerging class of special concrete that falls under the category of ultra-high-performance concrete. RPC offers very superior mechanical properties as compared to conventional concretes. The application of RPC is limited to some of the restricted applications such as, construction of nuclear power plants, precast bridges and girders. The generalized application of RPC is restricted due to the unknown behavior of RPC, when it is exposed to fire load. The dense and fine microstructure of RPC is prone to spalling under elevated temperatures. To combat spalling, RPC is produced with suitable fibres. In this study RPC is prepared with addition of polypropelene and polyester fibres with different fibre dosages like 0.1, 0.5 and 0.9% by weight of cement. The residual mechanical and durability properties of fibre-based RPC are evaluated at elevated temperatures ranging from 200 to 800 °C. Results indicate that the combined effect of polypropelene and polyester fibre-based RPC, possess good spalling resistance with 0.1% fibre content. Fibre dosage of 0.5% has shown superior residual mechanical and durability properties of RPC at elevated temperatures. Formation of pores, cracks and evaporation of fibres due to elevated temperatures is also investigated based on microstructure examination for all RPC mixes.