David Beresford tells the extraordinary story of how a young white South African couple, one a national sportsman, bombed the nuclear

The inside story of how the African National Congress made a mockery of atomic security to pull off one of the most dramatic coups of the apartheid struggle — blowing up the Koeberg nuclear power station near Cape Town in 1982 – — has been told by the young couple who carried out the attack.

The man who planted the bombs was the former South African national sword-fighting champion, Rodney Wilkinson. He was backed by his girlfriend, Heather Gray, a speech therapist – — whom he married soon after the bombing.

Wilkinson penetrated the plant’s security to plant four limpet mines on the two reactor heads at the power station as well as at strategic points under the control rooms.

The attack on the French-built nuclear installation — which, it was suspected at the time, would be used to produce plutonium for the construction of atomic bombs — was planned by the ANC Special Operations department to avoid loss of life and risk of radioactive fall-out. The bombs were detonated just days before the plant went on stream and nobody was hurt in the explosion and ensuing fire.

Despite later denials by the South African authorities, the ANC established that the enriched uranium fuel had been moved to the plant, but had not loaded it into the reactors. It was in dormant storage. The attack delayed the commissioning of the plant by about 18 months and cost the apartheid government an estimated half a billion rand.

South African security suspected the operation was the work of a group of highly trained saboteurs. But in fact it had been carried out by a former corporal in the South African Defence Force who made his escape from South Africa on a bicycle.

The Koeberg operation was born of chance in 1978. Wilkinson was living on a commune near Koeberg. The community ran out of money and Wilkinson — who had studied building science — reluctantly took a job at the nearby nuclear plant which was in the process of construction.

Wilkinson worked for 18 months at the plant. Encouraged by his girlfriend, Heather, he stole a set of Koeberg plans. The couple took them to newly independent Zimbabwe with the idea that they could be used by the ANC to launch an attack on the nuclear installation.

The ANC, whose ranks had been deeply infiltrated by Pretoria’s spies and had recently had one of their own agents jailed on charges of nuclear espionage, was initially suspicious of the “hippy” who had pitched up on their doorstep claiming to have penetrated what was assumed to be the most secure installation in South Africa.

After lengthy delays, during which the stolen plans were shown to Soviet and Western nuclear scientists for authentication and Wilkinson himself vetted, the ANC invited him to carry out the attack himself. He was taken aback by the request but agreed and returned to South Africa.

To his own surprise he gained fresh employment at Koeberg with the task of mapping pipes and valves at the installation, for use in case of emergency.

The ANC appointed a guerrilla commander in Swaziland to act as Wilkinson’s handler. Once a month he visited the mountain kingdom — a favourite resort for whites in search of illicit pleasures not available in puritanical South Africa — under the pretence of enjoying a “dirty weekend”. There he and his handler thrashed out strategy, designed to maximise embarrassment to the South African authorities while minimising the risk to human life.

They honed down possible targets to the two reactor heads, another section of the containment building and a concentration of electric cabling under the main control room. The destruction of the heads, which would be used to control the nuclear reaction, was to maximise the propaganda impact — made of 110 tons of steel, they were unlikely to be seriously affected by the blasts, but they demonstrated the ANC’s capacity to hit the heart of the plant. The other two targets were chosen to cause as much damage as possible. The date for the attack was set for December 16, the Day of the Covenant, which the ANC commemorated as MK Day in honour of Umkhonto we Sizwe.

Wilkinson and Gray dug up four limpet mines packed with incendiary charges from a roadside arms cache in a remote area of the Karoo. Hiding them in wine box-decanters in their Renault 5, they drove back to their Cape Town home in the suburb of Claremont where they hid the devices in holes conveniently dug by their puppy, Gaby.

>From there Wilkinson smuggled the mines one by one in a hidden compartment of the Renault through the perimeter security fence at the nuclear installation, depositing them in a desk drawer in his prefabricated office. From there he had to carry them by foot into the main building, through a security gate, hidden in his overalls.

The build-up to the attack was marked by a series of near-mishaps. At one stage an accidental short circuit started a cable fire. The incident was reported in the press and the ANC’s president-in-exile, Oliver Tambo — who was privy to the planned operation but not to details such as timing — released a statement claiming it as an ANC attack. The claim prompted a security scare which ended — – amid much derision towards the ANC — when the true cause of the blaze was confirmed by investigators.

In November the firm hiring Wilkinson informed him that they were laying him off at the end of the month, but then changed their minds and asked him to stay on another month. He turned this scare to advantage — telling them that in the interim he had taken another job and would have to leave on December 17, thereby obtaining cover for his planned disappearance.

As it transpired Wilkinson did not make the target date of December 16, but completed the operation the following day, a Friday. Setting the fuses to a 24-hour delay so that they would explode on the Saturday, when he knew the target areas would be deserted, he was then forced to undergo a farewell party on the premises with his fellow engineers, mentally praying that the time fuses were not defective. He flew that afternoon to Johannesburg and was driven with a borrowed bicycle to a point near the Swaziland border where he rode into exile.

The bombs detonated, but not quite as planned; the springs on the firing mechanism proved to have been brittle and the devices exploded over a period of several hours instead of simultaneously.

A few days beforehand South African commandos had attacked supposed ANC targets in the kingdom of Lesotho, killing 42 people including women and children. Tambo claimed the Koeberg attack was an act of retaliation carried out by a MK unit.

Wilkinson flew on to Maputo where he met Tambo in the ANC leader’s office, the two men crying in each other arms at their triumph. Gray, who had flown out of South Africa a week before the attack, joined Rodney there and they flew to Britain where they were married in Woodbridge, Suffolk. They continued working for the ANC after a period of isolation, returning home following the unbanning of the liberation movement and release of Nelson Mandela.