https://besacenter.org/perspectives-papers/russia-nuclear-missile-engine/
EXECUTIVE SUMMARY: The fatal explosion that occurred recently during testing of the Russian Burevestnik nuclear cruise missile raises many questions. Could it have been avoided? Was it a fundamental failure of the ambitious armaments plan declared by President Putin in 2018? Whatever the answers to these questions, the renewed trend toward an unconventional armaments race could deteriorate into a second Cold War.
On August 8, during a test of the nuclear-powered engine of the 9M730 Burevestnik cruise missile (petrel in Russian; nicknamed the SSC-X-9 Skyfall in the West), held on a floating platform in the White Sea near the Nyonoksa missile test site in the far north of Russia, a mysterious explosion occurred that killed eight people. The blast raised questions about the status of a new generation of five advanced weapons introduced by Putin in 2018, of which Burevestnik, described by the Russian president as supersonic and of unlimited range, occupied pride of place.
Five of the eight people killed in the explosion were Rosatom (Russian State Atomiс Energy Corporation) employees, and three more employees were injured. According to the company’s announcement, the disaster occurred while testing an “isotopic energy source for a liquid propulsion system.”
Shortly after the explosion, the weather monitoring agency Roshydromet reported a significant spike in radiation 40 km from the blast site. Also, in the city of Severodvinsk, which is near the explosion site in the Archangelsk district, the radiation level was reported to have jumped to 16 times the normal level. This led the alarmed residents to rush to stock up on iodine, which reduces the effects of radiation exposure.