Extending the life of the nuclear power plant at great risk for South Africa

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Koeberg nuclear power station. Picture: Eskom.

Preparations are underway for extending the life of Eskom’s 1,840 MW nuclear power plant in Koeberg, in what the South African state-owned power company considers the most complex project ever undertaken in the region. nuclear power plant since its commissioning some 36 years ago in 1985.

The replacement of three of the steam generators in Unit 2 of the 920 MW nuclear reactor is expected to begin in January 2022 as part of a shutdown scheduled to last 155 days. Subsequently, if all goes well, Eskom will begin replacing the second set of three steam generators on Unit 1 of the 920 MW reactor in October 2022, during a similar 155-day planned outage.

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In total, Eskom will therefore be deprived of at least 920 MW of basic supply from the nuclear power plant for ten months between January 2022 and February 2023. This will serve to lower Eskom’s average energy availability factor (AWF). below the current AWF of 62.% on Eskom’s power plant fleet over the past 12 months, and to increase the probability of load shedding during this period.

The steam generator replacement project is the biggest part of a mid-life refurbishment and safety upgrade at the Koeberg nuclear power plant. The current operating license expires in 2024 and these upgrades are required by the National Nuclear Regulator (NNR) to extend the life of the nuclear facility by an additional 20 years.

Budget and scope of the life extension project

The initial life extension project was budgeted at R20 billion (about $ 1.24 billion) in 2010, and Eskom confirmed that while there have been changes in the initial scope of work over the years following various studies and inspections carried out, the whole budget remains unchanged.

Eskom explains that there have been a few additions to the scope of the work, but there have also been a number of exclusions – such as replacing the condenser tubes which is no longer considered necessary. Thus, overall, the scope of the work is reduced, although the overall budget remains at R20 billion in 2021.

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The biggest component of the scope of work is the replacement of the steam generators at a cost of about 5 billion rand (about 310 million dollars). There have already been significant manufacturing issues and delays in replacing the steam generators from the originally planned completion date of 2018.

The three-year delay results from the scrapping of the first forgings of the steam generators made in France and the re-manufacture of the steam generators in China. However, Eskom indicates that the additional costs involved were borne by the contractor (Areva / Framatome), and that the overall cost of replacing the steam generator therefore remains within the initial budget.

Major costs of the life extension project

A general breakdown of the main items and costs constituting the R20 billion scope of work for the life extension works is presented by Eskom as follows:

  • 5 billion rand (about 310 million dollars): Replacement of the three steam generators of Unit 1 and the three steam generators of Unit 2, by Framatome / Areva.
  • 7 billion rand (about 430 million dollars): Review of the steam generator replacement project, including over 20 additional plant modifications resulting from safety analyzes and engineering studies; modifications to the water supply and heating systems, condensate extraction system, turbine steam control system and moisture separation system; other support contracts and site installations; project management and licensing costs; interest during construction; and contingencies.
  • 1 billion rand (about 62 million dollars): Replacement of unit 1 reactor head, control rod drive mechanism and reactor core instrumentation cable. The unit 2 reactor head was replaced in 2009/10 and is not included in the R20 billion budget but was covered separately in Koeberg’s maintenance and repair budget.
  • 0.6 billion rand (approximately $ 37 million): Replacement and expansion of the recharge water storage tanks (PTR) used to store borated water for the reactor cavity and the spent fuel cooling system.
  • 2 billion rand (about 120 million dollars): Maintenance and inspections specific to long-term shutdowns resulting from safety studies.
  • R 0.1 billion (about $ 6 million): Provisioning for resilience to external events – flexible emergency equipment to handle severe external events.
  • Undisclosed cost: Repairs, modifications and monitoring of the reactor containment building to include cathodic protection to prevent corrosion of steel reinforcement (rebar) in concrete.
  • Undisclosed cost: Replacement of heating resistors on pressurizers.
  • Undisclosed cost: Other factory modifications and upgrades for reliability and durability, such as transformer replacements, digital system upgrades, safety system upgrades, cooling water systems, piping and heat exchangers.
  • Undisclosed cost: Aging studies, investigations and safety reviews for the extension of the life of the plant, and preparation of reports to the RNR, including the safety file to the RNR at the end of November 2021, for approval of the extension of the operating license in 2024.

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Exclusions

Eskom indicated that the cost of repairs, refurbishment or replacement of electrical equipment such as high, medium and low voltage switchgear, circuit breakers, transformers, electrical protection equipment and instrumentation are not not included in the R20 billion life extension budget as these are part of Koeberg’s normal maintenance budget.

Likewise, any work done on steam turbines, such as replacing turbine rotors and rewinding power generators, is not included in the R20 billion budget, but is covered by the maintenance budget. normal. Eskom says that there is a lot of online condition monitoring equipment provided for turbines and generators, so this work is done as and when required and is not part of the extension project. lifetime.

Eskom also confirmed that repairs and maintenance of the power plant’s cooling seawater intake are underway. Eskom added that the seawater intake is structurally sound, but due to the aggressive saltwater environment, civil engineering maintenance and repairs have been ongoing since Koeberg started up. This work continues today and will continue for the next 20 years following the life extension. Again, Eskom claims these costs are not part of the R20 billion life extension budget, but are covered by Koeberg’s normal maintenance and repair budget.

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Additional risks of the life extension project

In a recent press conference, Eskom’s COO Jan Oberholzer indicated an additional risk to the Koeberg life extension project resulting from the loss of key qualified personnel at the nuclear power plant. He said he was “nervous but confident” that the additional planning work done would allow Eskom to get the job done properly without any major issues.

However, the final safety case report for the life extension project has yet to be submitted by Eskom to the NNR by the end of November 2021 for approval. This presents a very tight schedule for Eskom to resolve any issues raised by the NNR, just over the holiday season, ahead of the first outage in January 2022.

Eskom cannot say for sure that there will be no surprises in the NNR’s response to its safety case submission at the end of November 2021. However, unless “curved balls” do arise, Eskom does not plan. unexpected new demands. coming from the NNR.

In a complex job of this nature, there is always a risk that unexpected problems and delays will arise, which were not originally anticipated. However, Eskom believes that these issues can be addressed in the normal course of events.

Hopefully Eskom is right …

Chris Yelland is Managing Director of EE Business Intelligence


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