Modernising the I&C at Loviisa nuclear plant11 March 2015
Loviisa’s first attempt at a full upgrade of its I&C systems, a project called Lara, proved unsuccessful because of the complexity and sheer scale of the undertaking. Building on the painful lessons of that experience a new project, Elsa, with new contractors, is underway. By Ulf Linden
Loviisa has two VVER-440 pressurised water reactors of Russian design. Loviisa 1 has been in operation since 1977 and Loviisa 2 since 1980. The plant's operating licences were granted for 50 years, so unit 1 is licensed to 2027 and unit 2 to 2030.
The reactors, turbines, generators and other main components were imported from the former Soviet Union.
The steel containment and its ice condensers were manufactured under Westinghouse licences. The safety, control and automation systems also employ Western technology. Simatic and Teleperm systems from Siemens are used for normal process control and Siemens safety automation is used for engineered safety feature actuation systems (ESFAS).
The reactor trip system, reactor controller, control rod limitation system and neutron flux measurement system are of Russian origin.
When Loviisa 1 started operation in 1977 it was one of the most automated nuclear power plants in the world, but for some years it has been clear that continuing operation with the original automation systems would be challenging from both a technical and economic point of view. The main driver for the modernisation of these systems is therefore to ensure safe and reliable operation to the end of plant life.
New nuclear safety regulatory guides, which were released in 2013 by the Finnish Radiation and Nuclear Safety Authority and came into effect on 1 December 2013, have increased the scope of the modernisation. The new requirements are stricter than the old ones and some changes to the automation systems are being made to enhance safety. These form part of the modernisation programme.
Some additional plant modifications are also being made in response to lessons from the Fukushima accident. New cooling towers will use air for residual heat removal (in addition to the existing sea water cooling) and in the fuel ponds temperature measurement and cooling is being improved.
The present automation upgrade project started in May 2014, and is the second attempt to renew the automation at the plant.
The first project, Loviisa Automation Renewal, dubbed Lara, was awarded to a consortium of AREVA and Siemens and it started in 2005. It was terminated in early 2014, when both parties (supplier and purchaser) agreed that the large scope and considerable complexity of the project meant it would be significantly delayed. The Lara project scope included renewal of all automation systems across both units. It also included renewal of control rooms and simulators.
The new project, called Elsa, for which Rolls-Royce was selected as main contractor, has a more limited (although still ambitious) scope. To make the implementation more manageable the number of functions and systems to be renewed has been reduced.
Elsa (so-named because the project kick-off date was 14 October, which in Finland is the "name day" of Elsa) is confined to renewing the automation systems for reactor protection, reactor control, reactor power limitation and for the most important safety functions. The scope also includes improvements in the short and long term accident management systems.
Rolls-Royce will deliver all the new safety-classified automation systems, and the safety system automation will use Rolls-Royce's Spinline platform.
The Rolls-Royce scope includes planning, testing and installation. The company will also provide a hardwired backup for accident management, reactor trip and engineered safety feature actuation systems (ESFAS).
Metso has been subcontracted to provide monitoring systems and normal process control systems (employing Metso DNA for operational instrumentation & control). The Metso scope includes field design and on-site installation.
Lessons from Lara
The new project aims to fully take on board experience gained with the Lara project, which was thoroughly analysed. The main recommendations included:
- Focus on change and configuration management;
- Reduce the scope;
- Avoid implementing unnecessary upgrades and improvements in old but well functioning automation systems;
- Freeze the design;
- Minimise changes at the plant and in the project.
- An extensive body of material describing Lara lessons learned was assembled and Elsa project participants have been trained using this material. Although it will benefit from these lessons, the Elsa project of course remains challenging. Challenges include:
- Managing the interface between new and old systems, as the automation systems are only being partly renewed. A lot of effort is going into investigating the interface's old cabinets and marshalling racks.
- The tight schedule. The plan is to complete the renewal on both units in three stages during the normal planned annual outages in 2016, 2017 and 2018.
- Change and configuration management. Changes are made all the time to the plant, and during the automation upgrade implementation further small changes may also be made. In the system and detailed design phase of the new automation changes may also have to be made to the scope, because it is not possible for functions in the new digital automation systems to replicate exactly the analogue systems. The project and plant teams may also propose improvements to the new system, and the system supplier may suggest modifications because all requirements cannot be fulfilled. Experience with Lara highlighted these challenges.
There are many other plant upgrade projects under way, such as turbine modifications and post-Fukushima projects, including provision of additional air cooling, as already noted. Their impacts on the automation renewal must be carefully analysed.
Well-functioning instrumentation & control systems installed by Siemens and AREVA in phase one of the Lara project - including waste water process control systems at both units, monitoring and control of the 110kV/20kV switchyard and significant safety automation at both units (control rod control and indication systems, preventive protection safety functions and modifications in control rooms and training simulators) - will be retained and interfaced with the new Rolls-Royce Spinline platform.
Current status of Elsa
The Elsa project will be implemented in three stages:
- Stage 1: Renew preventive protection functions to create clear defence-in-depth lines (normal process control; preventive protection; reactor trip; and manual backup). The principles of redundancy, diversity and physical separation must be fully taken into account within and between these defence-in-depth lines. This part of the project is due to be completed at the plant in 2016.
- Stage 2: Renew accident management systems. This is planned for 2017.
- Stage 3: Renew the reactor protection system, together with the reactor control and reactor power limitation system. This stage will also include renewal of the neutron flux measurement system. Implementation is planned for 2018.
Elsa started smoothly in May 2014, greatly helped by being able to make use of the Lara project organisation, which was already in place and ready.
During the power plant outages of August and September 2014, interfaces with the existing automation system were investigated and the basic design of the new systems for stage 1 was completed, as scheduled, before the end of 2014. This will allow the first stage to be implemented at both units during 2016, subject to approval of the basic design concept by the regulatory authority.
Pre-installation work for stage 1 will be done in 2015, with final installation in 2016.
Design work in support of the second and third stages of the project is under way and the whole project is due to be completed by the end of 2018.
About the Author
Ulf Linden, Fortum, Loviisa power plant, Finland