Rosatom
© Reuters
The explosion of a secretive isotope-powered missile engine was so powerful that it blew the device into pieces and threw workers off a sea platform, Russian nuclear agency Rosatom said. Searches for the missing went on all day. Dramatic details of the tragedy that rocked the Arkhangelsk region this week, and that fueled western tabloids with rumors of a new Chernobyl-like disaster, were shared by the state atomic energy corporation on Saturday.

It revealed that the blast, which killed five employees and seriously injured three others, took place on a sea platform and followed a series of trials.

The test of the classified "liquid-propellant engine" went smoothly at first, but then the device caught fire and blew up, Rosatom said.

The blast threw several employees into the sea, giving some hope of finding them alive.

Water in high latitudes is ice-cold even in summertime, but search attempts lasted the whole day, until hopes faded. Only then were the five operatives declared dead.

Three more workers have been hospitalized with various traumas and burns. The agency lauded the work of the employees, who, it said, were well aware of the dangerous nature of experimental engine tests.

The five who perished had been working on an "isotope power source" for a propulsion system. An increase in background radiation was registered on the test site, but the measurements are said to have soon returned to normal.

The city of Severodvinsk, located some 30km east of the test range and hosting a key shipyard of Russia's Northern Fleet, added fuel to rumors after authorities posted - and then deleted - news of a brief radiation spike to 0.11 microsieverts per hour, with the norm standing at 0.6. The report said that it lasted for half an hour only, and the daily average wasn't seriously affected.

The secrecy surrounding the ill-fated test inevitably gave rise to conspiracy theories.

Pictures of hazmat teams taking measurements and specially-prepared ambulances transporting the injured were used to support some panic-inducing media headlines, while tabloids speculated over the type of weapon involved in the test.

However, rumors of a serious radioactive cover-up have not been supported on the ground, and neighboring Finland has not registered any deviations from normal levels. The Russian military has, meanwhile, refuted a report that a Rosatom vessel, capable of collecting radioactive waste, was dispatched to Severodvinsk, saying it had actually been undergoing scheduled trials.