Brian Parkin takes look at the past, present and possible futures of nuclear power in Scotland. If you want to read more on this topic do try the excellent paper by Simon Butler on ten reasons why nuclear is not the answer.
A MURKY MYSTERY
On a per head of population, Scotland has the highest concentration of nuclear installations in the world. Apart from the Advanced Gas Reactor stations (AGR’s) at Hunterston B, (Ayrshire) and Torness (East Lothian), both owned and operated by eDF, the other nuclear sites in Scotland are where nuclear power generation has ceased- but where licences remain for the continuation of nuclear power generation in the future. In total the number of nuclear sites in Scotland is five- the 2 operating reactors plus Chapelcross, Hunterston A and Dounreay in Caithness. In addition to the civilian generating sites, there are military related sites at Faslane on the Clyde, Vulcan in Caithness and Rosyth near Edinburgh. (See map).
The Chapelcross and Hunterston A stations are the now decommissioning Magnox-type reactors, ten of which formed the UK’s entrance into the world’s nuclear power race. The Magnoxs were developed over a number of years and so shared little in design and operational characteristics- but what they all shared was a graphite (carbon) core which was gas (CO2cooled) and which moderated (controlled) the speed of the Uranium235 fission- which in turn provided the heat for the steam that drove the electric turbines. All Magnox reactors are currently in the hands of the Nuclear Decommissioning Authority with the intention to render the sites decontaminated and safe- a process for which the technology is yet to be developed and the costs unknown.
The Dounreay site is the home to that ultimate nuclear fission fantasy- the Fast Breeder Reactor (FBR). The two FBR plants were intended to reproduce their own Plutonium fuel during operation- but in actual fact produced less power than consumed by their works canteens(!). The Dounreay plants present the greater decommissioning challenges due to the extremely high and extended half-life of their Plutonium fuel rods and the extreme levels of site irradiation.
GOING, GOING, GONE?
The remaining AGRs at Hunterston B and Torness, along with the other six such stations in the UK, both share a generic design fault in the form of micro and hairline cracks in their moderator block graphite cores. This has brought forward the AGR closure programme with the problem so acute that the Hunterston B station is due, on a 40% load to shut-down within the next 4 years. This will leave Scotland with the remaining Torness AGR at a 1360 MWe rating on declining load factor. According to current plans Scotland will have ceased to have any nuclear generated electricity within its borders by 2031.
But even after some 60 years of nuclear failure it might be premature to read the funeral rites.
From its very inception, nuclear power has been beset by problems. Its capital costs have historically been prone to going through the roof. Also, recurring safety issues have led to operational caution in the form of low load-factors with down-time and unscheduled outages leading to negative revenues from unreliability- all of which have made nuclear power the most expensive and unreliable on the system.
But in order to disguise the real cost of nuclear power, it has always been given a ‘first on the system/must run’ status to which in addition it has been covered by transferred subsidies from other forms of generation. In other words, nuclear power has historically inflated the overall cost of electricity to the disbenefit of the consumer. Nuclear power has been one of the biggest aggravating factors in the persistence of fuel poverty.
Also, despite a continuous torrent of glossy promotions, the nuclear industry has always hidden the cost and environmental hazards of the back-end matter of waste ‘management’; how to safely treat ‘spent’ fuel rods that represent a lethal radiological threat, plus hundreds of tonnes of reactor core material which must be ‘managed’- kept out of harms way in sealed containment for an incalculable number of years. At no stage in the planning and design of any reactor have such technological and economic challenges been factored in.
ECONOMIES OF SCALE 1: BIGGER IS BETTER
The continual economic failure of nuclear power has given rise to an enduring industry fantasy- basically by building bigger reactors with higher power densities and outputs, an ideal reactor design will become a generic model with large run replication and better reactor efficiencies. Hence some thirty years of shift-shaping a Pressurised Water Reactor of around 1,400 Megawatts output in the hope of a tooth fairy. So around the year 2000, optimum size thinking settled on the 1,600 MWe European Pressurised Water Reactor of the type now being constructed at Hinkley in Somerset- a sister of the Normandy and Finnish massive over-run and over-cost failures. So instead:
ECONOMIES OF SCALE 2: SMALL IS BEAUTIFUL: THE SMALL MODULAR REACTOR (SMR)
This is the obverse; a Small is Beautiful alternative to the Bigger is Better doctrine. The big sell of the SMR is a reactor that it is small, therefore requiring a smaller site footprint. It is also a modular plant that can be factory assembled and delivered with each unit- the reactor, plus cooling system components, steam turbine, pressure vessels and steam generator that when assembled form a single module that just requires being bolted into an outer shell and utility services like an Ikea kitchen flat-pack- or so the promotional goes. Also, once assembled, the reactor core can be loaded with fuel and control rods- all without the need for refuelling during the lifetime of the plant- about 40 years. The concept of the SMR is derived from earlier military Pressurised (Light) Water Reactors that were developed during the 1950-60’s to power nuclear submarines and aircraft carriers. Typically, such a reactor would be rated at around 30MW electrical output- and in the US and Russia such ‘mini’ SMR’s have been undergoing operational trials.But in many ways, the SMR is pretty well a conventional reactor sub-species in that its produced energy is derived from nuclear fission with Uranium235 as the fuel.
However, in the UK Rolls Royce have been scaling up their SMR designs to much bigger out-puts to more conventional power station ‘set’ sizes of 330-440MWe. Initially, this would seem to contradict the aim of the objective of compact size units- which to some degree is illustrated with the image of a SMR reactor encased in primary containment shell on the back of a low-loader truck. Also, the slender diameter of the reactor primary containment promotes the impression of technical simplicity-an impression dispensed by the cutaway illustration- added to which is the reality of the most demanding of shell pressures and an internal temperature hotter than the sun.
Initially, the sales spiel regarding the relative simplicity of the SMR is based on a claimed design and operational simplicity and flexibility of operation- along with claimed low capital costs of some 30% less than ‘conventional’ Pressurised Water Reactors. And it is here that SMR is now being projected as the answer to the need for a‘baseload’ component in a mainly renewables- but largely intermittent generating capacity. And with outgoing AGR nuclear stations at Hunterston and Torness- plus declining output from the gas-fired station at Peterhead, a smaller, lower cost and flexible SMR has some attraction.
Scotland; now virtually at the end of its fossil power generation history faces a future of almost unlimited renewable energy power generation technologies. Wind, wave, tidal, hydro, geo-thermal and solar power has recently begun to combine in powering Scotland for whole days without fossil or nuclear inputs. That is the future; not with a nuclear component that as ever offers jam tomorrow- but in the present offers the highest cost and most dangerous energy on the planet.
Dr Brian Parkin. July 2021.