Engineering Simulation is a sophisticated multi-purpose technology allowing the users of simulators to run various engineering activities thanks to the possibility of representing the behavior of the plant under normal and adverse conditions, and of modifying the simulated plant architecture and components, adjust a huge set of parameters, test alternative operational solutions. Engineering Simulators have been developed worldwide for performing plant design, integrated safety analysis, verification and validation of systems and components and human factors studies. These tools also play a role in developing and maintaining key nuclear skills, as knowledge repositories for training at various levels of expertise. The ‘ENES’ Strategic Project (proposed by ENEA within NUGENIA framework) aims at designing in detail the most urgent improvements to the current generation of Engineering Simulators for Gen II – Gen III NPPs in order to define the key characteristics of a new generation of Enhanced Simulators that can respond adequately to the various issues raised by the Fukushima accident and to other key targets of the international agenda for nuclear plants safety.
1. INTRODUCTION AND OBJECTIVES
The ‘ENES’ Strategic Project (proposed by ENEA in the NUGENIA framework [1] and recently (October 2016) proposed as a Research & Innovation Project under the EURATOM call [2]) is to design in detail the relevant and agreed most urgent improvements to the current Engineering Simulators for Gen II – Gen III NPPs in order to promote the development in the short-medium term of a new generation of ‘Enhanced’ Engineering Simulators that respond adequately to the issues raised by the Fukushima accident and other key targets of the international agenda for nuclear plants safety. This objective will be achieved through the definition of an innovative simulation architecture including both ‘classic’ models categories and ‘innovative’ software models such as those for the simulation of extreme natural events and advanced tools for predicting the dispersion in the environment of radionuclides released in case of severe accidents and their potential effects on population. For each model category a few alternative solutions will be identified for giving a remarkable flexibility and applicability to the new architecture. In particular ENES will examine in detail the possibility of using - in each simulation area – one more complex and one simpler software solution, for allowing future users to select the heavier codes only for the activities where this is necessary, while keeping the calculation burden not excessive through the use of the simpler fast running options. The domain of analysis of the simulators will grow from the current main systems and buildings of one reactor, to the whole NPP extension and the surrounding territory for describing with a three-dimensional approach the interactions with the environment. The innovative concept will be turned into a first prototype of enhanced simulator, that will be demonstrated through case studies based on a real LWR under operation. The demonstration will be performed on the Pisa University hardware platform NUTEMA (that is basically a knowledge management and simulation system, see Fig. 1) and with support from the HPC (High Performance Computing) CRESCO system at ENEA. One specific relevant motivation for the development of enhanced simulators derives from the analysis of the Post Fukushima Stress Tests and the linked ENSREG recommendations focusing on a deeper consideration of extreme natural events in the design and safety verification of NPPs. ENES will therefore include new models to be integrated in the engineering simulation environment, as solutions to problems so far dealt with in simple ways, if not neglected, especially those related to extreme weather events (e.g. hurricanes, tornadoes, floodings).
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FIG. 1. NUTEMA simulation and knowledge management platform.
Finally, increasing computation speed beyond real time will also allow using ENES-based future simulators as a Decision Support Tool during plant life, when operators’ decisions can be eased by fast and accurate analysis of alternative action consequences.
2. OVERALL CONCEPT AND METHODOLOGY
The overall objective of the ENES Project [1], [2] is to design in detail the desirable improvements to the current generation of Engineering Simulators (ES) for Gen II – Gen III NPP. The project will identify the R&D needs within the NUGENIA Roadmap that can be at least partially satisfied through a new generation of Engineering Simulators. Topics dealing with design and plant upgrading, probabilistic and deterministic safety assessment, analysis of accidents originated by single or multiple extreme external events are among those to be benefited by future simulators. The analysis of the expected user needs will go in parallel with the identification and analysis of the ongoing developments for the currently used software models in existing simulators and of the
‘innovative categories’ of models that can be introduced in the short term (e.g. those concerning Extreme Natural Events). The result of this extensive comparison between needs and possible solutions coming through simulators innovations will be the detailed definition of an Enhanced Simulation Architecture (ESA) that will include both the macroscopic aspects (e.g. the agreement of the ‘simulation areas’ to be covered in the new tools, or what will be the extension of scope of the new tools) and more ‘microscopic’ detailed aspects such as the definition of the best alternative software models to be used, the specific metadata to be exchanged among these software tools, the relationships between some of these models and a Geographic Information System (GIS) or with a High Performance Computing (HPC) platform.
The definition of the Enhanced Methodology will allow the selection of a variety of alternative software tools available worldwide for covering the extended functionality of the new simulators. ENES project doesn’t aim at defining a ‘unique’ very specific architecture that can be implemented only with a given set of software models. And it would be unrealistic to try to materialise the future ESA by means of ‘whatever’ tools will be made available in the market for covering a certain ‘area of simulation’. So, the keyword in the identification of
‘alternative tools’ compatible with the ESA will be ‘balance’, by avoiding both an excessive architecture rigidness and a not manageable hyper-adaptability to any type of software models dealing with the identified simulation areas. The below reported preliminary scheme of a possible software architecture (Fig. 2) reflects the key idea of identifying systematically the ‘classic’ and ‘innovative’ simulation areas, and consider the best fitted software
models in each area for defining ‘alternative solutions’ for implementing the same flexible innovative simulation architecture for future enhanced ES. The scheme highlights the identification of key simulation areas in core modelling (CORE-SIM), Primary and secondary cooling (RCS and SEC), auxiliary and emergency systems (AUX, EMER), containment and severe accidents (CONT, SA), External Events and NPP Impacts (EXTEVE and IMP), electric systems (ELSYS).
FIG. 2. First trial architecture for enhanced engineering simulators.
3. EXPECTED IMPACTS
ENES will produce various kinds of impacts concerning different categories of end-users of project outcomes. Here the differentiated impacts are shortly described as a function of the identified stakeholders [2].
3.1. Impacts on Research Organisations
ENES consortium Research Organisations are active in the simulation sector and in particular in the realisation of advanced simulators in the energy sector and the nuclear field in particular. The technical-scientific achievements planned in ENES will grow significantly the expertise and the competitiveness of these partners in the context of the R&D sector, thus easing the creation of new funding opportunities both at national and international level.
3.2. Impacts on utilities operating NPPs
The availability in the next years of an enhanced generation of engineering simulators will allow NPP utilities to better satisfy the requirements for the new NPPs (EUR requirements or more specific utility
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requirements). Good examples can be a better design of safety enhancement systems and an assessment of the potential effects of extreme natural events on the integrity of key plant systems and components.
Improved simulators will support the optimisation of non-electric applications of NPP (e.g. for integrated production of electricity, feeding of district heating systems or provision of steam to nearby industries).
Enhanced engineering simulators will improve the training capabilities of all kind of utilities engineers (designers, operators …), will increase the opportunity of using these simulators as a Decision Support Tool during plant life (for analysing the effects of alternative actions in delicate or crucial situations), and will represent a strong basis for developing or improving full scale Training Simulators. Therefore, ENES will enhance innovation capacity within utilities, and will strengthen their competitiveness.
3.3. Impacts on simulator vendors
ENES Euratom project proposal involves two simulator vendors of international value. ENES results will give to these two commercial companies building and selling engineering simulators since many years a set of innovative solutions for developing enhanced simulators for their future customers. Notwithstanding their evident competence and competitiveness, ENES most relevant results will enhance their innovation capacity and help them to create new market opportunities thus triggering the growth of these companies. Moreover, the strong dissemination and exploitation effort planned in ENES will benefit in these terms also the other actors in the international community of simulators vendors.
3.4. Impacts on Training Capacity
The outcomes of ENES will affect the training capacities of organizations beyond the utilities, such as Technical Safety Support Organizations (TSO) or National Safety Authorities (NSA). This additional impact meets the following expectation from the Amended Nuclear Safety Directive: “In order to ensure that the proper skills are acquired and that adequate levels of competence are achieved and maintained, all parties should ensure that all staff having responsibilities relating to the nuclear safety of nuclear installations and to on-site emergency preparedness and response arrangements, undergo a continuous learning process. That can be achieved through the establishment of training programs and training plans, procedures for periodic review and updating of the training programs as well as appropriate budgetary provisions for training”.
3.5. Impacts on nuclear industry
ENES project sees industrial organisations involved both in the consortium and in the ‘advisors and users board’. Such entities will gain from the ENES results the possibility to have in their portfolio of Design and Safety Assessment tools a variety of solutions for coping with various specific problems and the possibility to make use of integrated enhanced engineering simulators for better design, improved safety assessment, use of future simulators as DST in current and near future NPPs. These effects will enhance their innovation capacity and will strengthen their competitiveness and facilitate the growth of such companies.
3.6. Impacts on involved SMEs
ENES project involves also a few SMEs either as partners or as planned subcontractors. These companies operate in specific technical sectors that are of high strategic value for ENES (e.g. nuclear engineering, software development, EC projects management, impacts of energy systems). Participation in ENES will increase innovation capacity and will create market opportunities and chances for companies growth.
3.7. Impacts on the society as a whole
Better simulators for designing and assessing at best the new generations of NPP will contribute to the
‘sustainable development’ of nuclear energy, thus contributing to the limitation of emissions of greenhouse gases, but also protecting air quality from polluting and health-damaging emissions from fossil burning plants. By supporting the initiatives and guidelines on the safety of NPP, the project will also give its contribution to the limitation of the probability and severity of possible future NPP accidents, also considering the risks connected
with the more frequent and heavier extreme weather events that could be in future the ‘initiating events’ of new severe nuclear accidents: a new generation of reactors designed with a new generation of simulators, in which the consideration of extreme natural events will be the rule and not the exception, will represent an additional protection against this sometimes underestimated but growing risk for NPPs.
The architecture of the ENES Euratom proposal is shown in Fig. 3.
FIG. 3. Organisation of the ENES project work packages.
ACKNOWLEDGEMENTS
Acknowledgements are here made to the organisations having cooperated within the development of the ENES Project idea under NUGENIA association, and-or the preparation of the first ENES proposal under the Euratom call 2016-17 (as either partners or members of the advisory board), namely Tecnatom (E), Gen-Energija and Zel-En (Si), AREVA and Heich Consult (D), Ansaldo Nucleare and NINE srl (Italy), GSE Systems (S), UJV (Cz), L3 (Can). The authors hope these organisations will continue supporting the development of the ENES Project.
REFERENCES
[1] ENES Template 2 – NOIP section in the NUGENIA, web site: www.nugenia.org [2] ENES Proposal for topic NFRP1 of Euratom call 2016-17 (submitted 5th October 2016).
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