In a few years, vast metal-cutting machines will be brought into Sellafield and used to slice into the sides of the B41 silo before mechanical grabs pull out and sort through its contents. Then this radioactive debris will be mixed with liquid glass and allowed to solidify, a process known as vitrification, before it is kept for subsequent storage in underground vaults. Isolating this material will be immensely difficult, however: B41 will have to be covered and sealed to ensure no leakage of radioactive material.
At the same time, the giant cutting machines employed to slice open the silo will have to negotiate the treacherous, tight concourses that separate Sellafield's different buildings. These are lined with cabling, ducts and, most worrying of all, elevated pipes, called pipe-bridges, that carry radioactive liquid waste around the site. Damaging or opening up one of these could have disastrous consequences.
Hence the care taken by engineers as they prepare their plans for B41 while their colleagues continue their work at the silo's sister plant, B29, where decommissioning work has already begun. In effect, B29 is simply a huge covered cooling pond that once stretched between the heat stacks of Piles 1 and 2.
Fuel rods were removed from these two reactors, moved into the cooling pond of B29 and split open. Most of this material was removed for reprocessing but several tonnes of waste and old fuel still lies below the pond's thick milky waters and it is the task of Steve Topping, leader of the building's decommissioning team, to ensure that this is extracted and safely stored.
Calm, with greying hair, Topping has a reassuringly confident air about his work despite the fact he has to deal with tonnes of nuclear waste and old oxide fuel whose exact composition and location is unknown. The stuff in the pond has been down there for 50 years," says Topping. Today B29 is showing its age and looks more like a dirty old dock than a pool with its crumbling grey concrete, grimy brickwork and old ducts and sections of corroding pipes.
The water is filled with green algae and has the clarity of Milk of Magnesia, which defies all efforts to see what lies beneath. To clean it up, robot machines will soon begin to split open the submerged skips in which old waste and fuel from Piles 1 and 2 are stored. The radioactive sludge at the bottom of the pool will then be pumped into a new tank that is now under construction beside B Then the internal linings of its walls will be scraped clean of radioactivity before the edifice is taken down, concrete section by concrete section.
At the same time, the most dangerous waste will be vitrified ready for disposal. The whole process will take at least 10 years to complete - and that is just for a single building. On top of the dismantling of B29 and B41, in which the waste from Britain's atom bomb programme is stored, there are the headaches that will be involved when dealing with the contents of B30 and B These hold the leftovers from the nation's first civil reactor programme, a series of reactors known as Magnox plants.
Eleven of these were built and two are still in operation. Piles of the waste they have generated is to be found around Sellafield awaiting the attention of engineers like Topping, who has spent his working life at the site. The buckets are then fed through an enclosed hole in the wall to a waiting RAPTOR master-slave robot arm encased in a box made of steel and 12mm reinforced glass. An operator uses the arm to sort and pack contaminated materials into litre plastic drums, a form of interim storage.
Once the room is cleared, humans can go in. Working hour days, four days a week in air-fed suits, staff are tasked with cleaning every speck of dust and dirt until the room has been fully decontaminated. The process of getting suited up and into the room takes so much time that workers only spend around 90 minutes a day in contaminated areas.
In other areas of Sellafield, the levels of radiation are so extreme that no humans can ever enter. Sellafield is so big it has its own bus service. Two shuttles run clockwise and counterclockwise, ferrying employees between buildings.
A drive around the perimeter takes 40 minutes. Train tracks criss-cross the ground as we pass Calder Hall and park up next to a featureless red and black building. It is here that spent fuel from the UK and overseas nuclear power plants is reprocessed and prepared for storage.
The waste comes in on rails. Flasks ranging in size from 50 tonnes to tonnes, some measuring three metres high, arrive at Thorp by freight train and are lifted out remotely by a tonne crane. Once in the facility, the lid bolts on the flasks are removed and the fuel is lowered into a small pool of water and taken out of the flask.
The flask is then removed, washed, cleaned and tested before being returned to the sender. Every day 10, litres of demineralised water is pumped in to keep the pool clean. At present the pool can hold 5. Conditions inside the Shear Cave are intense: all operations are carried out remotely using robots, with the waste producing sieverts of radiation per hour - more than 60 times the deadly dose.
The dissolved fuel, known as liquor, comprises 96 per cent uranium, one per cent plutonium and three per cent high-level waste containing every element in the periodic table. On April 20, Sellafield workers found a huge leak at Thorp, which first started in July A later report found a design error caused the leak, which was allowed to continue undetected due to a complacent culture at the facility.
The leak caused 83 cubic metres of nitric acid solution to seep from a broken pipe into a secondary containment chamber - a stainless steel tub encased in two-metre-thick reinforced concrete with a capacity of cubic metres.
The leaked liquid was estimated to contain 20 metric tons of uranium and kg of plutonium. The leak was eventually contained and the liquid returned to primary storage. We work in value streams, focusing on what we are really here to do, and prioritising what we do and how we do it to maximise value. We currently have four value streams:.
Keeping Sellafield safe and secure is our priority and governs the decisions that we make every day. One of the ways that we can make Sellafield safer is by removing the nuclear risks and hazards posed by our oldest building; the legacy ponds and silos.
Our work demands a mix of direct employment and supply chain capability. Together they are a team of more than 11, nuclear experts. Innovation spans the spectrum of bespoke technology to fit-for-purpose solutions. Our supply chain partners are developing solutions for us that can be exported to other customers. We research and invest in areas with the potential to add greatest value to our mission. We have a responsibility to deliver new projects at Sellafield that will support our mission.
We must do this safely, securely, to the agreed specification, on schedule, within budget and with due regard to the environment. We aim to build relationships with the Nuclear Decommissioning Authority, regulators, customers, stakeholders and the supply chain, recognising that we can achieve more together than we can alone. Our governance arrangements ensure that there is a clean line of sight from the strategic decisions made by our Board to the day-to-day decisions made by our teams.
Our nuclear operations are carried out in line with the appropriate regulatory authorisations and permissions. Sellafield has been nearly 80 years in the making. Today, Sellafield covers 6 square kilometres and is home to more than nuclear facilities and the largest inventory of untreated nuclear waste in the world.
The Sellafield site has been operational since the s, when it was used as a Royal Ordinance Factory supporting the war effort and the national defence programme. The factory was constructed to inspect and package small arms ammunition. By far the largest quantity of nuclear waste is far more recognisable and mundane, and only half of it is generated by the nuclear industry. It includes things like gloves, protective clothing, paper towels, metal and concrete.
It also includes clothing and items used by doctors and nurses during medical procedures like x-rays, and by researchers in laboratories across the country. We have invested heavily in recycling and treatment options so that we can reduce the amount of low level waste that is sent to the national Low Level Waste Repository. Intermediate level nuclear waste includes materials such as fuel element cladding, contaminated equipment, and plutonium contaminated materials. It is chopped up, mixed with a special grout inside high-integrity stainless steel drums, and stored in engineered stores.
Highly active liquid waste is a by-product of reprocessing used nuclear fuel. The molten mixture is then poured into stainless steel containers and allowed to solidify.
We store the waste in a specially engineered store, pending its final disposal in the UK, or return it to its country of origin. The nature of our work at Sellafield means that one of our core capabilities is the ability to manage and store special nuclear materials safely.
Sellafield has been more than seven decades in the making. Our teams work hand-in-hand with colleagues from the supply chain. And behind the people working to remove nuclear hazards is an army of people looking for a better, safer, more efficient way to get the job done.
Every day we are building greater certainty, and we will be the generation that makes demonstrable progress in cleaning up the site. Tags: Achievements , Decommissioning milestones , Hazard reduction , Sellafield.
Comment by P Edant posted on on 24 September Comment by sarahcorlett posted on on 24 September A place for anyone with an interest in the management of radioactive waste and nuclear materials, and the progress of cleaning up nuclear sites in the UK.
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