Name of the Project
Koeberg nuclear power plant (NPP) steam-generator replacement (SGR) project.

Location
Western Cape, South Africa.

Project Owner/s
Eskom.

Project Description
The current steam generators in Unit 1 and Unit 2 at the Koeberg nuclear power station have been in operation since 1984 and 1985 respectively. The aim of the project is to extend the design life of the nuclear power station by 20 years to 2045.

The project involves the replacement of all six steam generators for units 1 and 2.

The SGR project involves the design, manufacture and installation of three steam generators in each of the Koeberg power plant’s two operating units, as well as safety analyses and studies to comprehensively demonstrate the plant’s design integrity, with no adverse impact on public and worker safety and health or the environment, including the enhancement of nuclear safety.

The new generators will incorporate modern design features for easy maintenance and inspections, and improve heat-transfer efficiency, leading to an overall efficiency improvement of Koeberg.

The installation of the generators will be conducted during the scheduled refuelling, inspections and maintenance outages of the two units at Koeberg power station. Eskom is on track and progressing according to plan for installation during the next unit 1 and 2 outages.

The other major components of the life-extension plan include:

• a refuelling water storage tank replacement project, completed in 2019;
• the Unit 2 reactor pressure vessel head replacement, with the installation thereof scheduled for 2022;
• the replacement of feed-train components on the conventional power plant, which is conducted during maintenance outages; and
• the ongoing Koeberg safety aspects of long-term operation assessment. The assessment is designed to provide the equipment-ageing management confirmation to enable the Koeberg plant to operate beyond its original life span of 40 years to at least 60 years.

Capital Expenditure
Not stated.

Planned Start/End Date
Not stated.

Latest Developments
A major milestone was achieved with regard to the completion of the steam generator replacements on Koeberg Power Station’s Unit 1 in March.

The first steam generator has been removed from the containment building and placed in the storage building that has been erected to house the steam generators.

The logistics of moving the steam generators from their installed position (vertical), out of containment (horizontal at an elevation of 20 m) and placing them on a flatbed transporter (horizontal) is challenging. Each of them is 22 m tall, with a diameter of 4.5 m (top half) and 3.5 m (bottom half) and they each weigh over more than 320 t.

The other steam generators are ready to be lifted. This involves:

• rigging the remaining two steam generators out from their positions inside containment.
• rigging the three new steam generators into their exact position inside the containment building.
• performing the six critical welds (two per steam generator) that join the steam generators to the primary system piping.
• performing radiography on the welds to ensure they meet the code requirements.
• reinstalling all the access platforms that enable people to work all the way up the steam generators.
• reinstalling all the other piping connections – steam pipe at the top, feedwater pipe, and all the other smaller sampling and instrumentation connections – once access is available, and in all cases performing the required level of quality control.
• installing a new thermal insulation over the whole steam generator surface and all the pipes that were worked on.
• removing all the temporary equipment that was required to be installed to allow for the work to be done safely.

Thereafter, Eskom steel needs to complete the maintenance activities scheduled for the outage, commission all the systems, refuel the reactor and return the unit to service.

Owing to delays, Eskom has indicated that the original return-to-service date for the unit is no longer achievable. The generation production plan is, thus, being optimised to minimise the impact of the projected delay on the system.

Unit 2, which continues to operate safely while Unit 1 is in this extended outage, will undergo a similar long outage – starting in the latter part of 2023 ­– to replace its three steam generators.

The steam generators are the last large component replacements required to ensure that Koeberg can operate safely in accordance with the safety analysis that has been performed, and submitted to the National Nuclear Regulator in support of the application to extend the plant life by 20 years.

Key Contracts, Suppliers and Consultants
Framatome (main SGR contractor); General Electric (modifications to the balance of plant or secondary turbine system); and Jacobs Engineering (BoP hardware changes).
 
Contact Details for Project Information
Eskom media desk, email mediadesk@eskom.co.za.