The German city of Hamburg likely avoided a major technological disaster on May 1, when a freighter ship caught fire. It had several tons of radioactive material and explosives among its cargo, it was revealed.
It took 200 firefighters working for several hours to douse the fires on the Atlantic Cartier. The ship’s most visible cargo was some 70 cars, 30 of which were damaged in the incident. But now it was revealed that the vessel also had highly dangerous substances on board as well, which posed the threat of radioactive contamination to the area.
The operator of the Fukushima Daiichi nuclear plant has poured water containing boric acid into the No. 2 reactor.
The
move followed the detection of a radioactive substance, xenon, in the
reactor's containment vessel, indicating that nuclear fission may have
resumed.
Tokyo Electric Power Company poured boric acid solution
into the No. 2 reactor for one hour from shortly before 3 AM on
Wednesday.
Last Friday, TEPCO began operating equipment to remove radioactive substances from the No. 2 reactor.
The
device sucks out gas from the containment vessel and filters out
radioactive materials. The company has been analyzing the types of
radioactive substances and their density near the outlet of the device.
On
Tuesday, TEPCO detected xenon-133 and xenon-135, substances that are
produced during the nuclear fission of uranium-235. The company says the
possibility of nuclear fission inside the reactor cannot be excluded.
TEPCO
says even if nuclear fission has resumed, it should be on a small scale
as there have been no major changes in the temperature or pressure of
the reactor, or radiation levels at monitoring posts around the
compound.
The government's Nuclear and Industrial Safety Agency
says it is unlikely that nuclear fuel has begun melting again as the
density of the xenon is low and there has been no change in the reactor
temperatures. The agency says it will continue to monitor the xenon in
the reactor.
A
nuclear energy expert says the presence of xenon in the No.2 reactor
leaves open the possibility that localized and temporary fission could
still occur.
Professor Koji Okamoto of the University of Tokyo
Graduate School says substances from melted fuel that could undergo
fission are probably scattered around, but are unlikely to react.
He says, however, that neutrons from radioactive materials could react with the uranium fuel and other substances.
Okamoto
says a self-sustaining chain reaction that creates criticality is
unlikely to happen because huge amounts of boric acid have been poured
into the reactor.
He adds that these neutrons must be closely monitored to make sure fission does not take place.
The
professor also referred to a plan by the government and TEPCO to
achieve a state of cold shutdown by the end of the year. He says that if
fission reactions are not under control, it would not be a cold
shutdown.
Okamoto says TEPCO must locate the melted fuel inside and outside the reactor in order to prevent further reactions.
