Senior Reporter
The 140 tons of plutonium at Sellafield has huge energy potential, but the technologies needed to exploit it have yet to be proven.
Wednesday evening saw a repeat of a BBC4 programme I missed when it originally aired back in August. Britain’s Nuclear Secrets: Inside Sellafield was an hour-long retrospective on the UK’s nuclear history and the central role of the Cumbria site. The affable Professor Jim Al-Khalili took us on a journey through Britain’s nuclear age, from the Windscale reactors used to develop plutonium for the UKs first nuclear weapons, to the 1957 fire, the proliferation of cheap nuclear energy in the 1970s, and the Thermal Oxide Reprocessing Plant (Thorp) that still operates today at Sellafield.
Coincidentally, I had spent Wednesday morning at a press conference where Sellafield was the primary point of discussion. Officials from the Nuclear Decommissioning Authority (NDA) were joined by several academics to talk about the options for dealing with the 140 tons of plutonium that are currently stored at the site. The largest stockpile of civil plutonium in the world, it presents a multitude of problems and opportunities. Which outweighs which depends very much on who you speak to, and how optimistic you are in relation to the development of certain technologies.

It takes somewhere in the region of 5-10kg of plutonium to make a nuclear weapon, so 140 tons is a slightly worrying amount to have sitting in a concrete shed in Cumbria. While everyone at the press conference was at pains to point out that there are no major safety concerns with the current storage, it is widely accepted that a long-term plan needs to be formulated. This, however, is where things get tricky. The potential energy of the plutonium if converted to nuclear fuel is massive, but there are several competing technologies vying for endorsement, none of which are well proven as financially viable.
Top of the list – and the government’s current preference – is for some application that uses mixed oxide fuel, or MOX. MOX is made by blending plutonium with natural or depleted uranium to create a fuel that is similar, but not identical, to the low-enriched uranium used in most nuclear plants today. MOX can be – and in several European countries is – used in thermal reactors alongside uranium. But despite past concerns, there is in reality no shortage of uranium today, so no huge need to supplement it with MOX in current reactors. Where MOX could in fact lead to greater efficiencies is in fast reactors, but these are costly and difficult to operate, and would not make economic sense unless the cost of uranium fell.
To complicate matters further, developing MOX is by no means a straightforward process. A Sellafield MOX Plant was completed in 1997, didn’t actually begin operation until 2001, and was closed in 2011 after a poor performance record that saw it deliver just 5 tons of MOX in its first five years. To put that it into context, it was designed with a capacity for 120 tons a year. Total construction and operating cost was around £1.2bn. While France has had a degree of success in producing MOX, construction on the US’s MOX production facility at the Savannah River Site was recently pushed back a decade, and may not be in operation until 2033.

Another option on the table is PRISM. Developed by GE Hitachi (GEH), PRISM is a sodium-cooled fast reactor that uses a metallic fuel alloy of zirconium, uranium, and plutonium. GEH claims PRISM would reduce the plutonium stockpile quicker than MOX and be the most efficient solution for the UK. The problem is, despite being based on established technology, a PRISM reactor has yet to be built, and the UK is understandably a little reluctant to commit in this direction. Seen as something of a gamble, it remains in the running alongside the currently more favoured MOX option.
Amid all the uncertainty, one thing is for sure. Regardless of what decision is taken, a proportion of the plutonium will end up as waste and will need to be safely disposed of. One of the speakers at the press conference was Professor Neil Hyatt from the University of Sheffield. A materials science specialist, Hyatt is currently developing an immobilisation technique that can be used to render the plutonium unsuitable for weaponisation, allowing it to be more safely stored in the longer term. Using a form of hot isostatic pressing (HIP), the process mimics the formation of ancient minerals by using extreme heat and pressure to lock the plutonium inside ceramic based wasteforms.
According to Hyatt, the HIP technology is about a decade away from operation. Unlike MOX and PRISM, immobilisation has no prominent industry backers. In comparison to exploiting the plutonium for our energy needs, there is no great fortune to be made from disposing of it safely. But immobilising the entire plutonium stockpile may in fact be a more economically sound approach than reprocessing, says Hyatt. Some see this as madness, putting all that potential energy beyond the use of future generations. Others believe the technology needed to exploit that energy is decades away, by which point fusion and renewables will be better options. Just about the only thing the NDA could say with certainty, was that the right decision is more important than a quick one. We wait with bated breath.
Molten salt technology with thorium has been tested in the USA. This utilises nuclear waste as a fuel. We reported this on http://www.futureenergies.com
Although the new generation fission reactors have some significant materials problems to resolve they would probably be available for energy generation significantly before fusion reactors which still remain as ever 30 years away.
The Chinese are making significant investments in molten salt reactors,
http://www.the-weinberg-foundation.org/2012/10/30/completion-date-slips-for-chinas-thorium-molten-salt-reactor/
Other fast neutron reactors, required for Pu don’t seem to be so far advanced.
Best regards
Roger
Thanks for this article on the UK’s plutonium problem. The mismanaged MOX project here in South Carolina, at the US Department of Energy’s Savannah River Site (SRS), is plagued with design and construction problems and likely inspection inspection cover-ups. It is nothing to model a UK plutonium disposition program on. The failed US MOX project has been placed on a shut-down track by Congress, which is only funding it to barely survive. Given the host of construction problems, lengthy schedule delays, no MOX customers and inadequate funding it’s clear the project has failed. A big question hangs: when will the design and construction contractor, CB&I AREVA MOX Services, be investigated for waste, fraud, abuse and mismanagement of what has turned into a massive boondoggle? — Tom Clements, Savannah River Site Watch, Columbia, South Carolina, USA
But have they found a metal or other material which can withstand corrosion over time? New schematics and floor plans will do nothing for corrosion. Backup generators only last so long, the earth shifts with traveling faults.. Could it be the time to use wisdom and not chimp away at the apple of illusive knowledge.. Knowledge over wisdom gets us nowhere.
We would be “burning” that plutonium now had the-this time Tory- Government kept us on track for a fast or even fast breeder reactor. We seem prepared to pay uneconomic sums and rates to allow the wealthy to get wind farm and solar subsidies for pointless quasi-green posturing, yet won’t invest in technology that benefits every energy user. Of course, the total absence of an energy policy from 1997 to 2010 only made the situation worse.
Excellent synopsis of the status quo, thanks.
Two points. The first being we need to consider the plutonium as an asset for exploitation. We don’t have the money, energy security or disposal technologies to simply write it off, moreover fusion is always decades away. We need to he bold but also realistic and that would suggest investment in the prism system but surely only if we take a stake in the technology if we are going to be the Guinea pigs.
Secondly, we’ve come to this impasse due to a total lack of energy policy for the last 15 years. In this complex world where solutions demand research and investment and finance is hyper fluid we need a political system that takes the long view, protects sustained investment and plans accordingly. Simply put our political system is too partisan and too short term to make the right decisions.
In my opinion all long term schemes need to be devolved to QUANGOs like the new National Infrastructure Commission. Yes maintain democratic oversight and provide long term goals but allow the long term, day to day management to be run by a pseudo-aparty-political body.
Surely we could replicate this :-https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator
With regard to the RTG: It’s the wrong kind of plutonium – seriously. Different isotopes have wildly differing decay profiles and the stuff NASA use for RTGs is in short supply.
With regard to any kind of reactor using sodium cooling: A metal which burns fiercely when exposed to the atmosphere would not be my first, second or last choice in any environment, let alone when it may have radionucleide contamination circulating in it. Ask the japanese how well their cleanup at Monju is going.
It makes no sense to spend a fortune storing highly radioactive “waste” for thousands of years when this extremely valuable energy resource could be used to generate all the low carbon electricity that this country needs for the foreseeable future
We are very much locked in to the past with solid fuel based Nuclear fuel technologies … with their inherent limiting efficiency flaws (0.5% of fuel used). It would appear the SMR described is yet another one of these … while the PRISM Fast Breeder Reactor at least utilises fluid fuels (molten metal). A step in the right direction but again physiological inertia and business culture entrench the status-quo. The Nuclear industry is no different.
By investing in the development of Molten Salt Reactor (MSR) technology the very clear advantages a MSR can bring in reducing the Plutonium waste will become apparent (see Molten Salt Reactor in wiki). This mentions Britain’s exploration of the technology by AERE around the same time as ORNL in the states – both running out of funds at about the same time in the early 70’s … coincidence?
At a time where climate change is very much on the agenda it’s almost as if simplifying the current ‘steam driven’ Nuclear Technology with its flawed solid fuel system (low efficiency and tendency for Zirconium to draw oxygen away from surroundings when things get too hot … resulting in Hydrogen gas … having to vent this produced the explosions at Fukushima) and safety critical high pressure water systems should be higher up on the agenda.
This should be where the comparison to the slicker Molten Salt Reactor working at safer atmospheric pressure, yet more thermally efficient operation (Brayton compatible), should be understood as the obvious next step in the Nuclear technology strategy. Using an MSR based on a Thorium fuel (LFTR – Liquid Floride Thorium Reactor) as thermal spectrum reactor seems to have many advantages and should be the ideal option to pursue.
While entrenched in the past technology there appears a conundrum where the appeal of far-fetched future technologies sits more comfortably than those within easier reach. It would seem the moon-shot for Fusion Reactors grabs the headlines (and the funding) where a blind spot exists for the more practical step of running a ‘walk-away’ safe, more efficient, proliferation resistant, waste reducing, MSR Fission Reactor … that requires no huge input power to initiate & control it … just real commitment to invest as this is far too important an issue to depend only on the good intentions of a charitable organisation (Alvin Weinberg Foundation) to progress!
The MOX fuel is what is killing the Pacific Ocean since 311 at Fukushima . When will sites like this start to tell the truth?
The oceans are home to 4.5 billion tonnes of natural Uranium.