Limping along: EDF Energy looking to extend operational life of aging reactors AGAIN.

Nuclear Free Local Authorities, 18 Jan 24

The UK/Ireland Nuclear Free Local Authorities are concerned that EDF Energy, the arm of French state-owned Électricité de France which operates the UK nuclear fleet, has just announced its intention to further extend operations at its four remaining aging Advanced Gas-Cooled Reactor plants.

Hartlepool, Heysham-1, Heysham-2, and Torness first began generating in either 1983 or 1988, with an estimated operational life of 30 years. In 2023, the operating lives of Hartlepool and Heysham-1 were extended by two years from 2024 to March 2026, however the closure of Heysham-2 and Torness had previously been brought forward from 2030 to March 2028 because of ‘impacts on the graphite cores’.

The aging AGR plants will have been operating for at least 40 years by 2028, and the NFLAs’ core concerns revolve around the safety risk posed by the degradation of the graphite neutron moderators in each reactor.

NFLA Scotland Policy Advisor Pete Roche finds the rethink of the situation at Torness and Heysham 2 totally inexplicable: “In May 2020 we learnt that the cores of the four reactors at Torness and Heysham 2 were predicted to start cracking in 2022, six years earlier than previously thought. These last two AGRs have a significant design difference, compared to other AGRs which could make the cracking problem worse. Several commentators, at the time, questioned whether the two stations would make it even as far as 2028.

In 2020 the Office for Nuclear Regulation said the design difference at Torness and Heysham 2 could lead to graphite debris challenging the reactors’ ability to move or adequately cool fuel. And if the Regulators modelling predictions on the graphite core cracking were realised, then the reactors would not be safe to operate for another ten years. Heysham-1 and Hartlepool face similar operational challenges.

Yet in the ‘UK Nuclear Free Stakeholder Update’ published earlier this month, EDF company bosses state: ‘The prospect of further AGR lifetime extensions ([of] four power stations) will be reviewed again by the end [of] 2024 and the ambition is to generate beyond these dates, subject to plant inspections and regulatory approvals.’[1]

To support this ‘ambition’, EDF Energy also pledges to: ‘invest a further £1.3 billion over the next three years (2024-26) to help sustain current levels of generation’ within the company’s Nuclear Operations Division.

The function of the graphite core and the impact of aging is detailed by the Office of Nuclear Regulation (ONR) on its website:

https://www.onr.org.uk/civil-nuclear-reactors/graphite-core-ageing.htm

‘As well as moderation, the fundamental safety requirements of an AGR core include allowing free movement of control rods, free movement of fuel and directing the flow of coolant gas to ensure adequate cooling of the fuel and core structure.  Essentially, significant weight-loss and cracking may compromise these safety requirements.
‘During operation, the graphite slowly loses weight due to oxidation caused by the reactor’s carbon dioxide coolant gas.  Loss of weight affects both the mechanical properties of the graphite brick, and reduces its effectiveness as a moderator.’

We raised our concerns that graphite core cracking could over time seriously compromise safety as far back as 2014 and most recently in correspondence, and in meetings, with officials from the ONR.

Our concerns and activities on this issue were outlined in our briefing No 250 ‘Update on the AGR closure programme’, dated 17 October 2022:……………………………………………………

Three AGRs at Dungeness-B, Hinkley Point-B and Hunterston-B have already closed, and are in the process of defueling, but those that remain continue to experience defects during their end-of-life cycle in addition to any cracking of the graphite core moderator.

Dr Paul Dorfman, Chair of the Nuclear Consulting Group, who is often called upon to comment on nuclear power and renewable energy issues by media outlets worldwide, is clear that closure of the AGRs is long overdue:

“All the UK nuclear reactors that EDF want to ‘life extend’ have histories of technical problems – by far the most significant is the cracking of the graphite bricks in the core moderator. The role of the graphite moderator is to slow down the fast neutrons to allow the chain reaction.

“Due to irradiation damage over time, the bricks crack and reactor core distorts. Channels run through the bricks, allowing control rods to shut-down the reactor in an emergency. Because the graphite core can’t be repaired or replaced, this means that core damage is a life-limiting condition.
This is why these reactor’s original operating design life was just 30 years.

“All things considered, much better to be safe than sorry. Shut them down.”

The status and operating history of the AGRs does indeed belie the claim of government ministers and industry supremos that nuclear is a reliable source of electricity generation; indeed, generation at the plants can best be described as ‘intermittent’, a term commonly used by detractors of renewable energy technologies……………………………………………..

There will doubtless be a point where it will simply be uneconomic for EDF Energy to continue generating electricity at these elderly plants, but Councillor Lawrence O’Neill, Chair of the NFLAs, wonders if EDF Energy’s motivation is in part driven by the need to generate extra income in the medium term given the significant delays in delivering Hinkley Point C:

“Frankly EDF Energy could do with the money from continuing operations at the four AGR plants. Hinkley Point C is being built at EDF’s risk and EDF’s cost. It is massively over budget and hugely behind schedule. It may well not be generating by 2028 or even by 2030, and broadsheet newspapers like The Telegraph and Guardian have recently speculated that the plant may even not be online before 2032. In the meantime, EDF Energy will be haemorrhaging cash”…………………………………… https://www.nuclearpolicy.info/news/limping-along-edf-energy-looking-to-extend-operational-life-of-aging-reactors-again/

January 20, 2024 - Posted by Christina Macpherson | safety