Ionising radiation and health hazards
General health hazards in use of ionising radiations, e.g. X-rays, nuclear radiation.
Environmental radiation: the effect of ionising radiation on humans depends on the type of radiation,
the activity of the source (in Bq), the time of exposure, and the type of tissue irradiated.
Measurement of background radiation.
Audiovisual resource material.
Health hazards of ionising radiations.
Radon, significance of background radiation, granite.
Medical and dental X-rays.
Disposal of nuclear waste.
from the bbc
In Japanese disaster films they like heroes who sacrifice everything for the greater good - stoic, determined, refusing to back down in the face of adversity or even certain death. These are the qualities the country admires. Now the newspapers here have a new band of heroes to lionise - the workers, emergency services personnel and the scientists battling to save the Fukushima nuclear plant, their fellow citizens and themselves.
We know little about them, except for the few whose relatives have spoken to the Japanese media. One woman told the papers her father, who had worked for an electric company for 40 years, had volunteered to help. He was due to retire in September. "The future of the nuclear plant depends on how we resolve this crisis," he was reported to have told his daughter. "I feel it's my mission to help."
The small group of workers who stayed at the site as the conditions worsened were dubbed "The Fukushima 50" - although now it is thought there are maybe twice that many working there. Rick Hallard, who worked in the British nuclear industry for more than 30 years, says the pressure on them will be immense, but that they will probably not feel it until it is over.
“If that place explodes, it's the end for all of us, so all I can do is send them encouragement” Maeda Akihiro
"They'll be focusing on the key risks and threats," he says. "They will have a very clear idea of what their priorities are."
'Life on the line' On Wednesday the government raised the legal limit of radiation they could be exposed to from 100 to 250 millisieverts. That is more than 12 times the legal dose for workers dealing with radiation under British law. But you would need to be exposed to a dose probably twice that maximum before you would expect to see the so-called "early effects" people associate with radiation sickness, like a lowering of white blood cells. People living close to the plant are being checked for radiation as they evacuate. You would need a level of exposure in the region of 1,000 millisieverts before you might feel nauseous or feel ill. The "late effects" of exposure to radiation may not occur for many years. It can increase the likelihood you will develop cancer, but this is only an increased possibility, not a certainty.
The person in charge of the operation will likely be some distance from the reactors, Mr Hallard says. "You need to be remote from the event to enable you to think," he says, "so that you don't miss things or react too quickly." "It's important to take the pressure off the person in charge." The workers might be faceless heroes for the moment, but their bravery has won them the admiration of many Japanese.
"They are sacrificing themselves for the Japanese people," says Fukuda Kensuke, a white collar worker in Tokyo. "I feel really grateful to those who continue to work there."
Fukushima Daiichi: What went wrong
Reactor 1: Was first to be rocked by an explosion on Saturday; fuel rods reportedly 70% damaged
Reactor 2: There are fears a blast on Tuesday breached a containment system; fuel rods reportedly 33% damaged
Reactor 3: Explosion on Monday; smoke or steam seen rising on Wednesday; damage to roof and possibly also to a containment system
Reactor 4: Hit by a major blaze (possible blast) on Tuesday and another fire on Wednesday
Walsh: What are health risks?
Foreign evacuations mount
"They're putting their life on the line," agrees Maeda Akihiro. "If that place explodes, it's the end for all of us, so all I can do is send them encouragement." The Japanese Self Defence pilots who have been flying the helicopters used to "water-bomb" the plant on Thursday, to try to help cool the fuel rods, have been restricted to missions lasting less than 40 minutes at a time, to try to restrict their exposure to radiation.
The Japanese Prime Minister, Naoto Kan, has paid tribute to all those involved in the efforts to stabilise conditions at the nuclear plant, describing how they are "making their best effort without even thinking twice about the danger". When this crisis is over, some of the stories of individual heroism will start to emerge. Several of those battling to cool the fuel rods have been injured. It must be hardest for their families, who sit and wait at home, not knowing what dangers their loved ones are facing, what damage they might have suffered and what problems might result in the years ahead. "I didn't want him to go," one man's wife told a Japanese paper. "But he's been working in the nuclear industry since he was 18 and he's confident it's safe."