Fast breeder accident covered up

The sodium leak at Japan's first power-generating FBR (fast breeder reactor) Monju, which occurred on December 8, was far more serious than first thought, according to the Citizens' Nuclear Information Centre (CNIC) in Tokyo. The government-owned PNC (Power Reactor and Nuclear Fuel Development Corporation) attempted more than once to cover up the seriousness of the leakage, said the CNIC. The government is now being forced to review Japan's FBR program. Though the leakage took place in the piping of the secondary cooling system and did not involve the release of any radiation, the accident was one of the most serious sodium leakage incidents in the history of FBR development, CNIC said. In the amount of sodium leaked (two to three cubic metres) it is second only to the leak from a storage tank at France's Superphenix in 1987. PNC and affiliated experts asserted that the leakage was far below the amount considered dangerous. Indeed, a leak of up to 150 m<3< from a secondary pipe was approved in the licensing safety review of the plant; it was concluded that most of the leaked sodium would pour onto the steel-lined floor and be recovered by a drain system without causing any serious problem. In reality, the leaked sodium reacted violently with the air, causing a spray-fire and filling the secondary coolant piping room C with fumes of reaction products such as sodium oxide and peroxides. Some fumes found their way into neighbouring rooms and to the outside through the ventilation duct, which was not shut off, in violation of the licensed operational procedure. Part of the steel liner and other metal structures were seriously damaged by heat and, presumably, reactions with sodium peroxide as well. If the 150 m<3< approved by the licensing review had leaked, the consequences would have been catastrophic. The PNC operations manual was very ambiguous about the circumstances in which the reactor should be closed down, CNIC charged. It took 90 minutes for the reactor operators in the control room to decide to manually shut down the reactor. On December 20, 12 days after the accident, it was revealed that the one-minute videotape released to the public through the media as the first record of the accident site was a highly edited version of two original videotapes which were four and 10 minutes long. The vice head of Monju plant admitted at a press conference that the videotape was edited because the original was too shocking, showing serious damage to the pipes and ducts and large amounts of sodium product spread around. The edited tape showed only a lump of sodium product in a corner of the room, all other pipes and structures appearing to be intact.