Accelerating reactor decommissioning

THE USA HAS THE LARGEST operating nuclear fleet in the world today, with 97 commercial units. But the fleet is now ageing. The average operating lifetime is 39 years and only eight are under 30 years old.

Although the US Nuclear Regulatory Commission (NRC) has granted licence extensions for a 60-year operating life at 89 of the 97 US units, some plant owners have recently opted for early retirements of their nuclear units at 45 to 50 years old. The oldest reactor in the US nuclear fleet, Exelon’s 49-year old 636MWe Oyster Creek BWR in New Jersey, closed in September 2018.

Over the past decade severe competition from electricity generation using low-cost shale gas has hurt the competitiveness of US nuclear. Record low wholesale electricity prices (around $20/MWh) plus the significant cost of life extension (PLEX) upgrades have together driven early nuclear plant retirements.

Low carbon zero emission credit (ZEC) payments provided by President Trump’s administration to energy utilities are helping to partially subsidise nuclear. But inevitably reactor closures are set to increase in the USA over the next 10 years, as 46 units (47% of the fleet) approach 50 years of operation.

The value of the US decommissioning market is projected to be $14 billion over the next decade as older reactors close well before their licences expire.

Economics of decommissioning

The 2008 global financial crisis changed the economics of nuclear decommissioning for energy utilities. Previously it made financial sense to defer nuclear decommissioning for 40 to 60 years after a nuclear reactor had been permanently shut down.

This approach is known as SAFSTOR in the USA. The plant is de-fuelled, removing 99% of the radionuclide inventory, the used fuel is placed in dry storage casks and the structure is placed into a passively safe storage configuration until final decontamination and dismantling takes place 60 years later, when the most hazardous short-lived fission product and steel activation product radioactivity has substantially decayed.

SAFSTOR also defers most of the cost of decommissioning, reducing the total liability due to discounting. Money has to be invested in a Trust Fund to pay for future nuclear decommissioning and until 2008 the discount rate for this provision was 2.2% per annum. The discounted liability for a typical $1 billion reactor 60 years into the future would be only around $271 million in 2020 money.

Now this position may be reversed. In some countries (including Japan, Switzerland and Sweden) government interest rates are below zero. The USA has not yet introduced negative interest rates but the suggestion has been made.

The negatively discounted value of a $1 billion nuclear reactor decommissioning liability 60 years into the future would be $2.4 billion in 2020 money. Realistically, the cost may be higher than $2.4 billion, because tighter radiological safety and waste disposal regulatory requirements are inevitable over the next 60 years. Regulation can increase costs unpredictably over long timescales.

Accelerated decommissioning in the USA

Decommissioning ahead of schedule, known as accelerated decommissioning (or Decon in the USA), allows the nuclear facility to be removed from regulatory control sooner after shutdown. Most of the nuclear power station site is then available for unrestricted re-use, except any area that houses the used fuel in dry storage.

Decommissioning is the responsibility of the plant owner. The utility makes regular payments into a decommissioning trust fund during the reactor’s generating life, and then draws down the fund to pay for decommissioning.

Today there is increasing recognition from energy company investors that decommissioning is not a core business of energy utilities, and so should be outsourced to specialists.

A trend is emerging in the US decommissioning market for specialist decommissioning service companies to establish a limited liability company — a special purpose vehicle (SPV) — that takes full financial and management responsibility for decommissioning. The SPV is financed from the Trust Fund. Of the 10 reactor units currently undergoing decommissioning in the US, six have been partially or fully transferred to decommissioning companies.

• Utah-based EnergySolutions pioneered this new approach at the Zion power plant, beginning in September 2010. EnergySolutions established a SPV (Zion Solutions), which took over NRC licensing and financial responsibility for Zion from Exelon. The $1 billion, 10-year project is the largest commercial nuclear plant dismantling ever undertaken in the USA, requiring 200 skilled workers on average each year, most of them local, and a peak workforce of 400. Decommissioning is expected to be completed later this year after final site radiological surveys and delicensing.
• EnergySolutions and AECOM have established a joint venture, SONGS Decommissioning Solutions, to decommission San Onofre, which was owned and operated by Southern California Edison. The joint venture is responsible for dismantling and decontamination, site restoration and reducing residual radioactivity to levels that allow for future site use. Decommissioning is due to begin in 2020 and is expected to create about 600 jobs during up to 10 years of dismantling. The majority of the workforce is expected to be hired locally.
• Comprehensive Decommissioning International (CDI), a joint venture of Canadian engineering company SNC Lavalin and US decommissioning firm Holtec, aims to accelerate the time required to release nuclear sites for unrestricted use to eight years at most, pending local regulatory approvals. Entergy completed the transfer of its Pilgrim plant to Holtec in 2019 for accelerated decommissioning. Entergy is also pursuing accelerated decommissioning for its Indian Point and Palisades plants when these close (due in 2021 and 2022, respectively).
• In 2018 US company NorthStar entered into a similar purchase and sale agreement with Entergy to decommission the Vermont Yankee plant. The deal includes transfer of the decommissioning trust fund of $696 million, in a first of a kind model. French state-owned company Orano and NorthStar have also established a joint venture called Accelerated Decommissioning Partners (ADP).

Accelerated decommissioning has an important practical advantage over deferred decommissioning: the SPV can utilise the existing knowledge of the nuclear site workforce and anticipate any problems with the decommissioning plan. Retired nuclear scientists have sometimes had to be recalled when unexpected problems have arisen decommissioning nuclear research facilities at the UK’s former Atomic Energy Research Establishment (AERE) at Harwell. Deferral of British Magnox and
advanced gas cooled reactors decommissioning for 60 years presents similar problems. The UK Nuclear Industry Association estimates that 70% of the UK’s specialist nuclear subject matter experts and managers will retire by 2025.

Accelerating British decommissioning?

Prime Minister Boris Johnson’s new Conservative government may need to look closely at accelerated decommissioning as Britain’s fleet of 14 graphite-cored advanced gas cooled reactors (AGRs) are all scheduled to close by 2030. The AGRs are currently largely owned by EDF Energy of France (Centrica has a 20% stake) but responsibility for decommissioning transfers to the UK Nuclear Decommissioning Authority after shutdown.

The NDA’s current strategy is to defuel shutdown Magnox and AGRs and place them into a 60-year passive care and maintenance phase, followed by 10-year decommissioning and final site restoration. Bradwell A, the demonstration site for this strategy, entered care and maintenance in 2018 and is scheduled for complete decommissioning by 2092. All of Britain’s 26 Magnox units are scheduled to enter 60-year care and maintenance within the next 10 years.

Accelerated decommissioning has previously been considered but rejected. The NDA’s 2008 business plan halted the proposed early clean-up of Magnox reactors because there was no disposal route for the 56,000t of carbon-14 activated graphite bricks from their cores. Britain’s planned geological disposal facility (GDF) will not become operational until at least 2040-2050.

Is there a route? The author notes that in Utah Energy Solutions, the US firm working on accelerated clean-up of Zion, owns the world’s largest privately held low-level nuclear waste repository. In theory, the UK could transport its graphite bricks to the EnergySolutions repository for final disposal.

The first major barrier is not technical but political: the UK follows the EU ‘Proximity Principle’, requiring wastes to be managed self-sufficiently and disposed as close as possible to the point of generation. The UK can change its approach (although it will require legislative change) having left the EU in January 2020.

With strong political will this could form part of the UK-US trade deal that now has to be negotiated. If so, Britain’s shut-down Magnox and AGR nuclear reactor fleets could be fully decommissioned by around 2035.

Author information: Ian Jackson, Nuclear Consultant