Reporting nuclear performance

19 November 2021

World Nuclear Association published a special update of the sixth edition of the World Nuclear Performance Report for the UNFCCC COP26 meeting. Jonathan Cobb shares some highlights

The sixth edition of the World Nuclear Performance Report is the first in which total annual global nuclear generation is lower than in the previous year. Overall, nuclear generation produced 2553TWh of electricity in 2020, down from 2657TWh in 2019.

As World Nuclear Association director general Sama Bilbao y León said in her introduction to the report, in any other year an almost four percent decline in nuclear generation would be an unequivocal disappointment. With climate change the key concern for world leaders in Glasgow, it would also be fair to say that such a fall in generation would have been an environmental disaster. Since coal-fired generation is still the leading source of electricity worldwide, the 104TWh of generation lost from nuclear could have avoided the emissions of up to 80 million tonnes of CO2.

However, in 2020, with overall electricity demand falling by around 1% and nuclear reactors increasingly being called upon to provide load-following support to the growing share of variable renewable generation, it was the resilience and flexibility shown by the global nuclear fleet that told a positive story. With global electricity demand reducing, the output from nuclear reactors still represented a share of just over 10% of electricity supplied globally — similar to recent years.

Nuclear reactors worldwide continued to maintain a high average capacity factor, despite the growing requirements for load following. The average global capacity factor in 2020 was 80.3%, maintaining the consistent performance seen over the last 20 years.

The progress required to achieve this high level of performance can be seen in Figure 1. In the 1970s, fewer than three out of ten reactors had an annual capacity factor above 80%. Since 2000 it has been more than six out of ten. 

This improvement has been achieved with many reactors built in the 1970s still in operation. So the higher capacity factors seen in 2020 have been reached not only through good performance from newer reactors, but through improved performance of older reactors.

The age of a reactor does not appear to be a barrier to achieving high capacity factors. The chart shows capacity factors for reactors of specific ages averaged over the last five years (or as many years as data is available, if less than five years). The data in the 2020 Performance Report are consistent with what has been observed in recent years: there is no apparent age-related decline in the capacity factors achieved by reactors. 

One of the least cost — and most immediate — ways of producing additional low-carbon electricity generation is to ensure that existing reactors continue to operate if they can.

The potential of extended operating lifetimes should not be underestimated. Figure 2 shows the age of reactors operating in any one year since 1970. (These are the capacities of reactors that have produced electricity in any one year, and does not include those reactors classed as operable, but which have not produced electricity, for example, some of the reactors in Japan over the last 10 years.)

With each decade the first major wave of nuclear build in the 1970s is reflected in the growth of reactors over ten, twenty, thirty and forty years old. The first reactors to operate for more 50 years have emerged recently. 

The fall in the rate of construction of new reactors from 1990 through to 2010 is reflected in a decline in subsequent decades. From 2010 the number of reactors in their third decade decline sharply, and over the 2020s we can also expect to see the number of reactors in their fourth decade of operation decline. 

Some reactors in the US have applied for 80 years of operation, and 60 years is the base-case for reactors being built today, so it is clear that there is great potential for decades of additional generation from reactors in operation today, which have a mean age of just over 30 years. A reactor at the fleet average age of 30 years would reasonably be expected to operate for longer than a new offshore wind turbine or solar panel just entering service.

Expansion is necessary

If net zero is to be a realistic target, a substantial expansion of nuclear capacity is urgently needed, in addition to retaining the existing fleet.

We can see the beginnings of such an expansion in Figure 3. In 2020 there were more reactors in their first decade of service than in their second or their third decade of service. These early promising steps need to be followed by a concerted effort to accelerate the pace of new nuclear construction.

There were just four construction starts in 2020, one in Turkey and three in China. This has already been exceeded in 2021, with first concrete poured on seven new reactor projects, four in China and one each in Russia, India and Turkey.

There were five reactors connected to the grid in 2020, two in China and one each in Belarus, Russia and UAE. This has already been matched in 2021, with two reactors grid-connected in China, and one each in India, Pakistan and UAE.

More than five years ago, the World Nuclear Association launched its Harmony Goal, for nuclear generation to be supplying 25% of the world’s electricity before we reach 2050, as part of a low-carbon generation mix. Over the last five years we have seen more governments making increasingly strong commitments to reach net zero on or before that date. Against such targets the need to meet, and potentially exceed, the Harmony Goal is clear. 

To achieve this goal the number of new reactor starts must increase, from the 5-10 that have started each year in recent years, up to 30-35 a year. This is a practical target, matching the grid connection rates achieved in the mid-1980s. 

The green light should be given to the many new build projects that could start soon. They will provide jobs, stimulate investment, and deliver low-carbon electricity potentially into the 22nd century. These new projects will take advantage of the capacity, know-how and supply chains rebuilt by recent FOAK nuclear projects. They can capitalise on the window of opportunity to lower nuclear construction costs created by the lessons learned from these recent projects.

Current regulatory requirements can present significant challenges to the deployment of new nuclear projects. This is a particular burden for new technologies, including small modular reactors. Governments, regulators, and industry must work together to accelerate the deployment of new nuclear projects, so that nuclear technologies can maximise their contribution to help decarbonise generation and other sectors beyond electricity supply.

More than 75% of the cost of nuclear electricity is due to financing costs. If nuclear plants are to be deployed on the scale required to achieve net zero by 2050 they will need access to affordable financing. Government commitment to nuclear energy will be essential to instil investor confidence, incentivise long term planning and attract private and public financing. ESG and climate financing criteria must be technology neutral, science-based and should be applied consistently to all economic activities.

To achieve net zero economy-wide will not only require decarbonisation of the electricity generation sector, but for all emissions to be eliminated, accounted for through offsets or compensated by negative-emission processes. 

Against such a target, nuclear technology will need to do far more than just decarbonise electricity. One case study in the Performance Report says steam from China’s Haiyang nuclear plant is being used to supply district heating — just one of the growing numbers of reactors being used for heating as well as electricity generation. 

For industrial process heat, a much higher temperature supply is needed. This is where a new generation of reactor designs could play a part. They could supply the heat needed for numerous industrial processes, such as glass or cement manufacturing. Both conventional and next generation reactors could be used to make hydrogen, either through electrolysis or thermochemical decomposition of water. 

Nuclear energy is the only low-carbon energy source that can produce low-carbon electricity and heat. The potential for nuclear energy to decarbonise hard-to-abate sectors of the economy is an opportunity that cannot be dismissed. 

Above, Figure 1: Long-term trends in capacity factors Above, Figure 1: Long-term trends in capacity factors
Figure 2: Mean capacity factor 2016-2020 by age of reactor Figure 2: Mean capacity factor 2016-2020 by age of reactor
Figure 3: Evolution of reactor ages Figure 3: Evolution of reactor ages

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