Apros® simulation software saves time and money in power plant development

Blog post
Joona Kurki,
Seppo Hillberg,
Rebekka Komu

Just imagine if you could know how to operate and control your power plant long before it is built, and even before any parts of it were procured and installed! Apros® dynamic process simulation software combines the accuracy of the best estimate analysis codes with the comprehensiveness and speed of full scope training simulators. The software proved to be crucial in modelling a new type of District Heating Reactor in its early development stages.

Apros® is a comprehensive, accurate and user-friendly software product for modelling and dynamic simulation of power plants, energy systems and industrial processes. Jointly developed by VTT and Fortum since 1986, Apros can be easily used to create a realistic digital model of an entire plant or system with all its interconnections, for example, by drawing diagrams and filling in component data sheets.

Typical applications of Apros include safety and performance analysis, automation testing and operator training. Safety analysis allows the user to execute experiments that could not be carried out in a real plant, helping to reduce risks and convince safety authorities. Similarly, performance analysis enables executing experiments well before the commissioning phase, helping, for example, to optimise the dimensioning of large process components.

Automation testing in Apros connects the automation application to the model for functional testing – thus shortening the commissioning time – while operator training provides a simulation model for hands-on training or self-study, ensuring the competence of personnel.

Aiding conceptual design of LDR reactor

VTT is continuously exploring potential application areas for Apros, and with the increasing need for decarbonising energy and heat production, simulation software can help to speed up the development of innovative solutions for a more sustainable future. Among these new low-carbon heating solutions is the LDR-50 (Low-temperature District Heating Reactor), a small modular reactor that relies on well-established pressurised water technology, combined with passive safety design.

The LDR reactor is connected to the district heating network via an intermediate water loop. Primary water that cools the fuel assemblies flows in a separate closed loop inside the reactor vessel, and the heat is transferred from one loop to another via heat exchangers.

The conceptual design of the LDR-50 was developed at VTT in 2020–2022, during which phase Apros played an important part as the main analysis tool – and, ultimately, helped to prove that the initial concept worked. The first task was to build an Apros model capable of analysing heat transfer and natural circulation in different geometries. Apros enabled testing both geometry and elevation variations of the heat exchanger, along with natural circulation, flow resistance and pressuriser size variations. Apros was also used to carry out load follow, operational, transient and accident analyses. In cases where the behaviour is highly three-dimensional – most importantly in containment heat transfer – Apros was complemented with CFD simulations (Computational Fluid Dynamics). CFD was utilised also when calculating flow resistance and distribution. 

Apros can solve the core neutronics with a point-kinetics approach or using its internal 3D nodal diffusion solver, depending on the level of detail and fidelity needed for the application.

Recent coupling work also allows data exchange between Apros and the modular core physics framework Kraken, developed at VTT, providing access to neutronics solutions based on the Ants multigroup neutron diffusion code and the Serpent Monte Carlo code.

Flexible collaboration with VTT

There are several ways of collaborating with VTT to start using Apros in your organisation. We can carry out safety analysis, engineering support and optimisation studies or build up simulation systems for your use. Alternatively, we can offer Apros software licences, providing all the support you need to build up your own simulation applications – including initial training of 2–3 days tailored to your needs.

We also provide software tailoring and integration services, involving top experts from the Apros product development organisation to ensure the best support.

All in all, dynamic simulation pays back through more informed engineering decisions early on, better performance of production systems and improved human capacity. As a flexible and user-friendly tool, Apros is an efficient way of boosting concept development, offering comprehensive model libraries, and a modern user interface with intuitive graphical access and powerful scripting. Also, the stable and continuous development of Apros, and its active user community help to ensure that users are covered well into the future.

Interested in saving time and money in your power plant development? Read more about our simulation services and don’t hesitate to contact us!

Apros® is a registered trademark of VTT and Fortum.

Matti Paljakka
Matti Paljakka
Solution Sales Lead, Nuclear Energy
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