Abstracts - VGB PowerTech Journal 5/2020
Nuclear power: The year 2019
Christopher Weßelmann
The development of nuclear energy continues to be characterised by a significant geographical shift in its expansion from its countries of origin in the USA and Europe to the new players in Asia.[more...]
Highlights of the World Nuclear Performance Report 2019
Jonathan Cobb
The world’s nuclear reactors made a growing contribution to supplying clean and reliable electricity in 2018. Global nuclear generation was 2563 TWh, up 61 TWh on the previous year. At the end of 2018 the capacity of the world’s 449 operable reactors was 397 GWe, up 4 GWe on the previous year. Nine new reactors were connected to the grid, with a combined capacity of 10.4 GWe. Seven reactors were closed down in 2018. The world’s nuclear plants continue to perform excellently. Growth is strong, with more than 20 new reactors scheduled to be connected before the end of 2020. For the industry to reach the Harmony goal of supplying at least 25 % of the world’s electricity before 2050, much greater commitment from policymakers will be required.
Safety Case Considerations for the Use of Robots in Nuclear Decommissioning
Howard Chapman, John-Patrick Richardson, Colin Fairbairn, Darren Potter, Stephen Shackleford and Jon Nolan
Decommissioning activities in the nuclear industry can often require personnel to undertake tasks manipulating plant, equipment and deploying tooling in close proximity to contaminated materials. The predominant risk associated with such work is exposure to radiological dose uptake from direct radiation, internal dose due to inhalation, or from wounds. There is an aspiration within the nuclear industry to remove the need for operators to undertake manual decommissioning activities by using ‘robotic systems’ which offer the benefit of overall risk reduction safer, sooner and cheaper. A vital part of the UK Nuclear Decommissioning Authority (NDA) mission is to help drive innovation to address the wide-ranging complex challenges across their sites and businesses. The NDA’s ‘Grand Challenges’ for technical innovation aims to remotely decommission gloveboxes by 2025 and provide a 50 % reduction in decommissioning activities carried out by humans in hazardous environments by 2030. This paper examines the underpinning Regulations, Standards and Technical Assessment Guides necessary for the deployment of ‘robotic systems’ to remove the need for operators to undertake manual nuclear decommissioning activities. It also investigates the information currently available to produce a safety case, together with commentary on work being undertaken by the UK National Nuclear Laboratory (NNL) who are currently reviewing technology and proof of concept trials to help future development in this area.
SMRs - Overview on international developments and safety features
Andreas Schaffrath and Sebastian Buchholz
Small modular reactors are one interesting option for new builds in almost all countries worldwide continuing to use nuclear energy for commercial electricity production. In this contribution first definitions, history and current developments of SMRs are presen-ted. Subsequently, selected trends of SMR development such as factory fabrication and transport, compactness and modularity, core design, improved core cooling and exclusion of accidents, features for preventing and limiting the impact of severe acci-dents are described. Further topics to be touched are the economic viability and competitiveness, licensing and the position of selected European countries concerning new builds. Last modellings gaps of the GRS simulation chain applied in nuclear licensing procedures are identified and a strategy for closure is developed.
Experimental and computational analysis of a passive containment cooling system with closed-loop heat pipe technology
Lu Changdong, Ji Wenying, Yang Jiang, Cai Wei, Wang Ting, Cheng Cheng and Xiao Hong
In this paper, a conceptual design of Passive Containment Cooling System with Closed-Loop Heat Pipe Technology (PCSHP) is studied using both experimental and computational methods. By studying on the thermal-hydraulic parameters in system running, such as temperature, pressure and flow rate, the paper mainly focuses on the start-up characteristics, the steady-state operating characteristics, the heat transfer capacity and the natural circulation capacity of the system. Hence, the principle experiment and GOTHIC simulation are carried out under start-up conditions, steady-state conditions and decay heat simulation conditions. The applicability and conservatism of the GOTHIC model is evaluated by comparing the simulating results with the experimental results. The rationality of the system design is validated by both the principle experiment and GOTHIC simulation. It is preliminarily judged that the heat pipe technology is feasible to apply to the Passive Containment Cooling System (PCCS) of nuclear power plant.
Physical and chemical effects of containment debris on the emergency coolant recirculation
Jisu Kim and Jong Woon Park
Physical and chemical effects of containment debris on the performance of emergency coolant recirculation are investigated to get insight on the cost-effective plant modifications to resolve USNRC’s Generic Safety Issue-191. The effects of debris sources on the sump screen performance are evaluated through the head loss calculation using NUREG/CR-6224 correlation. The amount of three predominant types of precipitates, i.e., sodium aluminum silicate (NaAlSi3O8), aluminum oxyhydroxide (AlOOH), calcium phosphate (Ca3(PO4)2) after 30 days of ECCS mission time are evaluated under various environmental conditions using WCAP-16530-NP chemical models. The debris interceptor is considered as a viable design option to reduce particulate debris such as unqualified coatings. The key parameters of each effect are deduced and recommendations for reducing their adverse effects are made through the present analysis: (a) The amount of unqualified coating debris is a major source of particulate debris and has a great adverse effect on the sump screen head loss by reducing porosity in the fibrous insulation, (b) The Cal-Sil insulation reacts with TSP buffer and significantly increases the generation of a gum-like chemical precipitant, (c) Spray time increases the chemical byproducts but the effect is smaller than that of buffer agent type and unqualified coating, (d) The debris interceptor, when verified, may play a vital role reducing head loss generated by coatings and fibrous debris mix.
Operating experience with nuclear power plants 2019
VGB PowerTech
The VGB Technical Committee “Nuclear Plant Operation” has been exchanging operating experience about nuclear power plants for more than 30 years. Plant operators from several European countries are participating in the exchange. A report is given on the operating results achieved in 2019, events important to plant safety, special and relevant repair, and retrofit measures.
A journey through 100 years VGB | Nuclear power
- French experience from the operation of nuclear power plants with pressurized water reactors
J. Kandel - The Contribution of Nuclear Energy to CO2 Reduction: Status and Outlook
H.-U. Fabian