Detailed boiler inspections extend UK reactor shutdowns

Global wood pellet demand is rapidly expanding
as consumers, businesses and regulators look for alternatives to fossil
fuels. Globally, wood pellet demand is projected to grow from an
estimated 23 million tonnes in 2014 to 50 million tonnes in 2024. These
findings were released yesterday in a new study by RISI, the leading
information provider for the global forest products industry.

“It’s a really exciting time to be looking at the wood pellet market.
We’re seeing strong demand in the European heating sector as high
energy prices drive consumers to look for fuel alternatives. Also,
policies that promote the generation of renewable energy are spurring
the use of pellets as a substitution for coal in power plants,” said
Seth Walker, Author and Bioenergy Economist at RISI.

“Additionally, Korea and Japan are beginning to enter the market,
creating a greater impact on global trade flows. Right now we’re getting
a small taste of what the market is going to look like in 10 years,”
continued Walker.

Global Pellet Demand Outlook Study analyzes and forecasts growing
wood pellet markets through 2024 by region. It focuses on the European
industrial market, European heating market, North American heating
market, and Asian industrial market.

Industrial users analyzed in this study include: Dong Energy, Drax,
E.ON, GDF Suez, KEPCO subsidiaries, Ontario Power Generation, RWE, and
Showa Shell.

Investigations into potential cracks in boiler spines at two
units at each of the Heysham I and Hartlepool sites are likely to take
until the end of the year to complete, EDF Energy has announced.

On 11 August, the company said it had shut down Heysham I unit 1, in
northwest England, in June after discovering a fault in a boiler spine
and taken the “conservative decision” to halt the second reactor there,
and two at its Hartlepool site in the northeast of England, “which are
of a similar design.” At that time, EDF Energy said it expected the
units to remain closed for about two months while investigations are
carried out.

However, the company has now announced that “a detailed and fully
resourced boiler inspection program” has begun at the four advanced
gas-cooled reactors (AGRs) which will take longer than original
envisaged. EDF Energy said this has involved “working with key suppliers
to identify and put the necessary equipment and people in place to
undertake this complex and specialized engineering program.”

Each reactor at Heysham I and Hartlepool has eight boiler units.
These boilers are arranged around their associated reactor in four
quadrants with each quadrant containing two boilers. Within each boiler
are tubes assembled in a coil formation around a central forged metal
tube called a boiler spine. The boiler spines support the weight of the
tubes around them.

Each boiler comprises a complex array of boiler tubes with a central cylindrical boiler spine that provides structural support to the tubes (Image: EDF Energy)

EDF Energy said that the first two boiler inspections have been completed and that no defects had been found on these spines.

The company said it will not restart the reactors until inspections
have verified that there are no further defects in the boiler spines and
that the cause of the crack found at Heysham I unit 1 is fully
understood. It will also develop modifications “to mitigate the impact
of any defects” and implement them if necessary.

EDF Energy’s director of engineering Mark Hartley said, “The
inspections “will give us confidence there is no cracking in any of the
other boilers and ensure that they are safe to continue operating. At
that point we will through our own very stringent safety assessment
processes develop our safety justification. We will then present this to
the Office for Nuclear Regulation for their approval.”

He added, “This would allow us to return the four units to power, but
recognizing at this stage that the boiler where we have observed some
cracking will remain shut down and isolated.”

EDF Energy said, “Depending on the progress of the program and any
necessary modifications, the company expects there to be a phased return
to service between the end of October and the end of December 2014.”