Rokkasho Reprocessing Plant Exposure of Inadequate Protective Measures against Aircraft Crashes Nuke Info Tokyo No. 99
It has been revealed during the Rokkasho Reprocessing Plant court case that the government approved Japan Nuclear Fuel Limited’s (JNFL) aircraft crash protection measures, despite the fact that they completely disregarded the issue of safety.
Due to the presence of the U.S. Misawa Air Force base and firing range just 30km south from the plant, it was considered necessary that the plant be designed to provide special protection against a jet fighter crash.
The plant building was constructed on the premise that a jet fighter would crash into the building after gliding through the air without any engine thrust. On this basis it was estimated that the crash velocity would be 150 m/s.
The plant’s major walls and ceilings were constructed to a thickness of around 120cm (maximum 180cm) in order to withstand the impact of an aircraft crashing into it at this speed.
However, at the time the plant was inspected it was confirmed that, according to a memo submitted by the operator of the plant, JNFL, the actual crash velocity could reach from 215 to 340m/s.
The memo listed problems that would arise if measures were taken to address these realistic velocities: “The plant’s structure would have to be modified, but consultation with SGN (a subsidiary of COGEMA) would take more than 2 years, which would have a big impact on cost.” “A velocity of 150 m/s was adopted during the inspection of the Uranium Enrichment Facility, next door to the reprocessing plant. This too would have to be adjusted to the higher speed.” “Changing the crash velocity would be very controversial in the local community and the suitability of the site would be brought into question.”
As a conclusion the memo notes, “in view of the effect on the plant’s design and the societal impact, the company (JNFL) wishes to adopt a crash velocity of 150m/s for all facilities which are required to take protective measures against aircraft crashes.”
So the approval of an aircraft crash velocity of 150m/s was made not on scientific grounds for safety reasons, but entirely on the grounds of “cost and time constraints and societal impact.”
With regard to the safety license inspection of nuclear facilities in Japan, there are two licensing steps: the first step is conducted by the government agency responsible and the second by the Nuclear Safety Commission.
The memo in question was submitted to the inspection carried out by the then Science and Technology Agency (STA), but had not been made public. This memo, which was presented by order of the court, revealed the seamy communications that passed between STA and JNFL.
Evidently the government fully accepted the company’s statements and neglected the safety issue. According to our own calculations, if an F-16 fighter jet crashed at a velocity of 215m/s, the thickness of the wall would have to be at least 170 to 190cm.
A further problem is that the impact assessment for an aircraft crash employs a hypothetical jet fighter which has lost engine thrust.
The protection of nuclear facilities has become a huge issue since the September 11th terrorist attack. Surely there is no country other than Japan making such unrealistic assumptions.
Japan’s regulatory authority and electric power companies doubly neglect safety protection. They dream up completely unrealistic accident scenarios and then they cheat on the specifics of the safety inspection.
And now the Rokkasho Reprocessing Plant, which only just managed to pass this deceitful licensing procedure, is still having trouble covering the cost of these flimsy ceilings and walls (about 11 billion yen).
by Masako Sawai (CNIC)