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Nuclear references in detail
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APROS nuclear references in detail

Analysis for TVO's Olkiluoto 3 - EPR under construction (PWR)   

TVO's Olkiluoto 3 unit is an EPR-type reactor under construction with a net electrical output of 1,600 MWe. The investment decision was made in 2003 and the planned start up is in 2012. VTT has performed extensive analysis studies for the Finnish regulator STUK. The role of VTT in Olkiluoto 3 has been to act as the regulator's technical support organisation. The goal of the analysis has been to support the regulator in the evaluation of fulfilment of the acceptance criteria. Analysis included independent reference calculations using Apros before plant-type selection, and continued in more detail with the EPR concept after the reactor-type selection. Apros was used in design-basis accidents analyses (DBA) including various transient and loss-of-coolant-accident (LOCA) analyses, steam generator tube rupture, and feed-water line break analyses. The analysis was done for reactor island, turbine island and containment.

For more information: Dr. Eija-Karita Puska, VTT.
Email: eija-karita.puska(a)

Engineering and analysis simulation of TVO's Olkiluoto 1 and 2 (BWR)

TVO's Olkiluoto 1 and 2 units are Westinghouse Atom-type BWR reactors and have been in operation since 1979 and 1982 in Finland. After modernisation and upgrade in several stages, these twin units have increased their net electrical power from the original 660 MWe to today's 860 MWe. The Apros simulation model of the Olkiluoto 1 and 2 NPPs has been used for engineering purposes for more than 5 years. The Apros model was created by Fortum Nuclear Services for Teollisuuden Voima Oy. The developed model covers all the main systems of the BWR unit. The developed simulation model has been used in many engineering applications, e.g. in the tuning of the level controllers of the new reheater system, analysis of the partial reactor trip, analysis of the periodic test, steam flow balance studies, reactor level measurement studies, transient analysis and turbine optimisations.

For more information: Kari Porkholm, Fortum.
Email: kari.porkholm(a)

Safety analysis, multi-disciplinary engineering and automation testing for Fortum Power and Heat's Loviisa NPP (PWR) during the on-going automation renewal project

Fortum Power and Heat owns and operates the Loviisa NPP units Loviisa 1 and 2 in Finland. The reactor of this twin unit is VVER-440-type, enhanced with containment building and ice condensers. The units started commercial operation in 1977 and 1980. After continuous modernisation and power up-rate projects, the net electrical output is today 488 MWe per unit. The automation renewal covers the renewal project of units 1 and 2, the modernisation of safety and normal automation systems, control rooms and operator training simulators. One of the project challenges is to minimise the shutdown periods; accordingly, the project is being executed in several stages and old automation is being replaced in phases. Apros has been used to develop integrated reactor island, turbine island, balance-of-plant, containment model. In addition, the complete automation has been initially simulated in Apros, and will be stepwise replaced by emulated automation provided by automation vendors Siemens and Areva.

Apros-based simulators are used extensively through the project life-time during the following project tasks:

  • Simulator for design and validation of the new digital automation systems
  • Simulator for design, testing and acceptance of new control room HMI design, and safety operation procedures; (integrated control room HMI and safety manual development and testing)
  • Testing simulator for testing the new automation systems and re-tuning the controllers during the factory acceptance tests
  • Full-scope simulator training of operators in a new, on-site training simulator facility (two training simulators)

All these multiple tasks are executed using the same basic Apros model with certain accuracy and scope variations between the project stages.

For more information: Kari Porkholm, Fortum.
Email: kari.porkholm(a)

Safety analysis for VVER-1000. Tianwan NPP, China (PWR)

The Apros engineering simulator model was created based on the VVER-91 plant unit and utilised in the engineering work.

For more information: Kari Porkholm.
Email: kari.porkholm(a)

Dynamic feasibility studies for planned new NPP unit Loviisa 3

Fortum Heat and Power has applied for a Decision-in-Principle to build a new NPP unit at the Loviisa site. Apros-based dynamic simulations have been performed for the option of a district heating system with a 70 km of hot water piping from Loviisa to the Helsinki metropolitan area (feasibility studies). Read more about Apros and District Heating.

For more information: Tommi Henttonen, Fortum.
Email: tommi.henttonen(a)