News

Model checking verifies the correctness of nuclear power plant safety systems

The study utilises model checking to address the insufficiencies of testing and simulation in the verification of safety systems.

Model checking as a process.

The object of Jussi Lahtinen’s dissertation was to find a more formal and mathematical approach to system verification and to develop model checking practices that are suitable for the nuclear industry. The traditional system verification methods, such as testing and simulation, do not have enough coverage to address the increasing digitalisation of safety automation systems.

         ‘Nuclear power plants have large safety systems in place that encompass multiple safety functions, such as the emergency diesel generator control system. In one of the techniques now developed, the system is divided into modules, and an algorithm is used for pinpointing the subset of modules that verifies the correctness of the system,’ says Lahtinen, explaining the practical implementation of the study.

At the architecture level, hardware failures in the microcircuits used for computing a number of functions, for example, are of pronounced significance. An individual software failure, on the other hand, is not all that safety-critical, given that the plant has a number of independent software-based safety systems in place.

         ‘Model checking is a highly effective method for finding latent design errors that may also be strange or unusual. Unlike testing or simulation, model checking is capable of achieving complete sequential coverage with respect to the requirement being examined,’ Lahtinen adds.

In the concluding phase of the dissertation, a method to support the structure-based testing of the function block diagrams used in the design of software-based systems was created. The method generates tests based on the structure of the function block diagram that describes the functioning of the safety automation system.

         ‘According to the feedback received from Fortum, the process of model checking as such may reveal errors that are easily ignored in testing. The comprehensive checking is also capable of analysing events over a very short time span,’ Lahtinen adds.

The results of the dissertation work have already been used in practical assignments for the Radiation and Nuclear Safety Authority concerning the Olkiluoto 3 project, for Fortum concerning the automation renewal of the Loviisa nuclear power plant, and for Fennovoima concerning the functional architecture of the foreseen Hanhikivi nuclear power plant. Further study on the integration of model checking with probabilistic risk analysis is already underway.

The dissertation work related to the study was supervised at the Aalto University Department of Computer Science by Professor Keijo Heljanko, and it was carried out at the VTT Technical Research Centre of Finland. A substantial part of the study was funded by the Finnish nuclear power plant safety research programme SAFIR. Model checking has been studied on a constant basis since 2007, and it is a very demanding method computationally.

More information:

Jussi Lahtinen
VTT
[email protected]
+3580 400 519 798

Keijo Heljanko
Professor
Department of Computer Science
[email protected]
+358 50 430 0771

Doctoral dissertation:  Model Checking Large Nuclear Power Plant Safety System Design

Defence of dissertation

  • Published:
  • Updated:
Share
URL copied!

Related news

dialogue
Cooperation, Studies, University Published:

Welcome to the 3rd online Unite! Dialogue event, hosted by INP Grenoble

Unite! is an European University Alliance of Aalto University and 6 other high-level European technical universities. Every six months, all staff and students from the seven universities gathered within Unite! meet for a dialogue and cooperate around the various themes and activities of Unite!. The 3rd Dialogue is organized, from March 8th to 10th, by Grenoble INP - UGA in a 100% online format and offers for the 1st time, a session open to the general public.
Tero Ojanperä
Appointments Published:

Former Nokia executive Tero Ojanperä believes intelligent platforms could be next success story for Finland

New professor of practice wants to apply his AI expertise and make sure usable innovations are brought from research papers into practical use.
Gan.uvia
Honoured Published:

Forbes AI Award to research on image-creating GAN models

The magazine pays tribute to the development of a model that starkly reduces the amount of data needed for generating new, artificial images
A magician is waving his wand and hype terms big data, 5G, IoT appear from his hat
Research & Art Published:

Digitalisation did not increase productivity as expected - researchers propose solutions for increasing productivity

There are large sector-specific differences in productivity with room for improvement, especially in manufacturing and construction.