Between January and July of 2022, National Grid Electricity Transmission were involved with a very small but highly important 400kV overhead line refurbishment project. The job was placed with Balfour Beatty Transmission and would consist of approximately 7.5 miles or 12km of Quadruple ‘Zebra’ L6 construction towers from Didcot to Cowley in Oxfordshire, UK. As that type of conductor is now viewed as obsolete and when a route is placed for an upgrade, ‘Araucaria’ 700mm2 conductor is being used in a standard triple configuration per phase. On this occasion the 4 x ‘Zebra’ ACSR 400mm2 conductors had been substituted with twin ‘Redwood’ 850mm2 AAAC and all new fittings leaving the towers looking somewhat strange in their new clothing.
Well, this is the intriguing part of this story that a short and apparently insignificant section of 1967 built, CEGB Supergrid infrastructure, should be associated in its relationship to a mega project that will one day be a source of energy production, the world has never seen.
I am talking of the JET project, Joint European Torus at the United Kingdom Atomic Energy Authority Culham Laboratories which goes under the name of the Culham Centre for Fusion Energy or CCFE. This overhead line known as 4VY comprises 36 towers on its route spanning gravel workings, the river Thames and open farmland. A very compact small route consisting of 24 D towers, 8 D30, 1 D90 and a L6DJT. Two further L6ST towers 19A/19B were constructed in 1980 inside the Culham site to reach the sub-station, 465m away from the route. The route 4VY found fame when in February 22 the Environment Agency placed a River Closure Notice on GOV.UK website. This would be affective on 20 April and 1 June for 4 hours on each occasion to be able to place netting over the Thames on scaffolding supports and recover it when finished. I believe that this is the first time that the Thames navigation has been impeded by transmission towers responsible for a closure. Then on its journey to Cowley, it is conveniently routed past a former airfield or Royal Navy Air Station referred to as RNAS Culham. The UKAEA acquired the disused airfield in 1960 and probably arranged for the route of 4VY to skirt the perimeter so that a high voltage connection could be installed once the infrastructure was constructed. They had 3x 400kV/36kV transformers installed from the sub-station and National Grid, presently allows 575MW of power to be used on the site from the grid. So, the engineers and scientists had to devise a way of upping the megawatts to the 1gw peak that would suit the needs for a pulse of that amount, they constructed two 700 tonne flywheel generators that would rotate at 200rpm in a flat plane and with the enormous pulse of electricity produced would allow the temperature to be raised to 1.5m degrees Celsius for the Plasma experiments. The Culham science centre boasts on their website that
What to read more?
Please buy Edition 1 from our Journals collection.
