Turbulence-induced vibrations prediction through use of an anisotropic pressure fluctuation model

In nuclear fuel rod bundles, turbulence-induced pressure fluctuations caused by an axial flow can create small but significant vibrations in the fuel rods, which in turn can cause structural effects such as material fatigue and fretting wear. Fluid-structure interaction simulations can be used to model these vibrations, but for affordable simulations based on the URANS approach, a model for the pressure fluctuations must be utilised. Driven by the goal to improve the current state-of-the-art pressure fluctuation model, AniPFM (Anisotropic Pressure Fluctuation Model) was developed. AniPFM can model velocity fluctuations based on anisotropic Reynolds stress tensors, with temporal correlation through the convection and decorrelation of turbulence. From these velocity fluctuations and the mean flow properties, the pressure fluctuations are calculated. The model was applied to several test cases and shows promising results in terms of reproducing qualitatively similar flow structures, as well as predicting the root-mean-squared pressure fluctuations. While further validation is being performed, the AniPFM has already demonstrated its potential for affordable simulations of turbulence-induced vibrations in industrial nuclear applications

Decision-support tool for assessing future nuclear reactor generation portfolios

Capital costs, fuel, operation and maintenance (O&M) costs, and electricity prices play a key role in the economics of nuclear power plants. Often standardized reactor designs are required to be locally adapted, which often impacts the project plans and the supply chain. It then becomes difficult to ascertain how these changes will eventually reflect in costs,which makes the capital costs component of nuclear power plants uncertain. Different nuclear reactor types compete economically by having either lower and less uncertain construction costs, increased efficiencies, lower and less uncertain fuel cycles and O&M costs etc. The decision making process related to nuclear power plants requires a holistic approach that takes into account the key economic factors and their uncertainties. We here present a decision-support tool that satisfactorily takes into account the major uncertainties in the cost elements of a nuclear power plant, to provide an optimal portfolio of nuclear reactors. The portfolio so obtained, under our model assumptions and the constraints considered, maximizes the combined returns for a given level of risk or uncertainty. These decisions are made using a combination of real option theory and mean\xe2\x80\x93variance portfolio optimization

Valuing modular nuclear power plants in finite time decision horizon

Small and medium sized reactors, SMRs, (according to IAEA, \xe2\x80\x98small\xe2\x80\x99 refers to reactors with power less than \n300 MWe, and \xe2\x80\x98medium\xe2\x80\x99 with power less than 700 MWe) are considered as an attractive option for investment \nin nuclear power plants. SMRs may benefit from flexibility of investment, reduced upfront expenditure, enhanced \nsafety, and easy integrationwith small sized grids. Large reactors on the other hand have been an attractive \noption due to the economy of scale. In this paper we focus on the economic impact of flexibility due to \nmodular construction of SMRs. We demonstrate, using real option analysis, the value of sequential modular \nSMRs. Numerical results under different considerations of decision time, uncertainty in electricity prices, and \nconstraints on the construction of units, are reported for a single large unit and for modular SMRs

TOP-DOWN WORKFORCE DEMAND EXTRAPOLATION BASED ON AN EC ENERGY ROADMAP SCENARIO

The EHRO-N team of JRC-IET provides the EC with essential data related to supply and demand for nuclear experts based on bottom-up information from the nuclear industry. The current paper deals with an alternative approach to derive figures for the demand side information of the nuclear workforce. Complementary to the bottom-up approach, a top-down modelling approach extrapolation of an EC Energy Roadmap nuclear energy demand scenario is followed here in addition to the survey information. In this top-down modelling approach, the number of nuclear power plants that are in operation and under construction is derived as a function of time from 2010 up to 2050 assuming that the current reactor park will be replaced by generic third generation reactors of 1400 MWe or 1000 MWe. Depending on the size of new build reactors, the analysis shows the number of new reactors required to fulfil the demand for nuclear energy. Based on workforce models for operation and construction of nuclear power plants, the model allows an extrapolation of these respective workforces. Using the nuclear skills pyramid, the total workforce employed at a plant is broken down in a nuclear (experts), nuclearized, and nuclear aware workforce. With retirement profiles for nuclear power plants derived from the bottom-up EHRO-N survey, the replacement of the current workforce is taken into account. The peak of the new workforce (partly replacing the retiring workforce and additionally keeping up with the growing total workforce demand) for nuclear experts and nuclearized employees is to be expected at the end of the considered period (2050). However, the peak workforce for nuclear aware employees is to be expected around 2020. When comparing to historical data for the nuclear capacity being installed at the same time in Europe, it is clear that the expected future capacity to be installed at the same time in Europe is significantly lower (factor of 2) than in the early 1980’s. However, it should be realized that the skills demand might have been more relaxed in those days. Furthermore, a steep rise in construction is to be expected within 10 to 15 years. This is due to the fact that not only additional nuclear power plants need to be built to keep up with the growing nuclear energy demand, but also the current nuclear reactor park needs to be replaced. In order to deal with this steep rise, the nuclear industry may consider buying time by extending the lifetime of the current nuclear reactor park.JRC.F.4-Innovative Technologies for Nuclear Reactor Safet

Top Down Workforce Demand from Energy Scenarios: Influence of Long Term Operation

The data evaluated by EHRO-N is based on an analysis of responses of surveys that are sent to higher education institutions in EU-28 and the enlargement and integration countries that offer nuclear- related degrees, and to nuclear stakeholders, who are active on the EU-28 and the enlargement and integration countries nuclear energy labor market. In addition to the bottom-up approach taken by the EHRO-N team, an alternative top-down modeling approach was undertaken by Roelofs and Von Estorff [2013]. The objective of the current analysis is to extend the previous study with an extrapolation of the workforce in the case that most European reactors will extend their lifetime. It was concluded from the previous study [Roelofs and Von Estorff, 2013] that the two energy demand scenarios which were considered did not reveal significantly different results. Therefore, the current analysis only takes into account the ’20 % nuclear electricity’ (officially called ‘Delayed CCS’) scenario from the EC Energy Roadmap 2050.JRC.F.4-Innovative Technologies for Nuclear Reactor Safet

Liquid metal thermal hydraulics R&D at European scale: achievements and prospects

International audienceA significant role for a future nuclear carbon-free energy production is attributed to fast reactors, mostly employing a liquid metal as a coolant. This paper summarizes the efforts that have been undertaken in collaborative projects sponsored by the European Commission in the past 20 years in the fields of liquid-metal heat transfer modeling, fuel assembly and core thermal hydraulics, pool and system thermal hydraulics, and establishment of best practice guidelines and verification, validation, and uncertainty quantification (UQ). The achievements in these fields will be presented along with the prospects on topics which will be studied collaboratively in Europe in the years to come. These prospects include further development of heat transfer models for applied computational fluid dynamics (CFD), further analysis of the consequences of fuel assembly blockages on coolant flow and temperature, analysis of the thermal hydraulic effects in deformed fuel assemblies, extended validation of three-dimensional pool thermal hydraulic CFD models, and further development and validation of multi-scale system thermal hydraulic methods