A father's goodbye: 'Live well. I cannot be home for a while'

"Please continue to live well. I cannot be home for a while." These words have come to encapsulate the struggle of the emerging heroes of Japan's nuclear crisis.

They were sent by email to the wife of one of the "Fukushima 50" – the middle and low-ranking operators, the technicians, soldiers and firefighters – who remain at the stricken power plant after all others have fled, exposed to dangerously high levels of radiation but fighting to stop it spreading further while haunted by the grim spectre of what may happen if they fail.

"They are running out of food... we think conditions are really tough. He says he's accepted his fate... much like a death sentence," the daughter of one of the workers wrote to a Japanese TV station.

But while the nation is in awe of their sacrifice, they do not know their names, with only the most sparing details available. And although they have become known as the "Fukushima 50", there are in fact about 200 workers rotating in and out of the most dangerous part of the plant 50 at a time, taking turns eating and sleeping in a decontaminated area.

Many of them volunteered for the task, labelled a suicide mission by some nuclear scientists, fully understanding the health risks involved, yet heading back to the heart of an expanding exclusion zone, from which at least 70,000 people have already been evacuated, and a further 140,000 told not to venture outside.

As they work to pump sea water on the dangerously exposed nuclear fuel rods, already thought to be partly melting and spewing radioactive material, 150 miles to the south, British, French, German and American nationals are in Tokyo boarding flights home on the advice of their governments.

Many workers at Fukushima, however, have to ignore any warnings to leave. It was the earthquake that first compromised the plant's reactors last Friday. While the workers tried to stabilise them, they knew a a tsunami was approaching. Thirty-one people have since been killed in the plant's various explosions.

"My dad went to the nuclear plant. I never heard my mother cry so hard. People at the plant are struggling, sacrificing themselves to protect you. Please dad come back alive," read a tweet by user @nekkonekonyaa.

When her father and his co-workers are done crawling through dark mazes, armed with flashlights and radiation detectors, wearing full body radiation suits and breathing through oxygen tanks, they likely will come back alive. But at what cost? Potentially deadly doses of radiation surround them, and their suits do little to prevent radiation from seeping into their bodies. Consequences could range from radiation sickness to long term side effects such as thyroid cancer.

Radiation levels in an hour at Fukushima have been measured at several times over that which a typical nuclear facility worker might be expected to exposed to in an entire career. The government has raised the maximum legal exposure levels in order to allow the work to carry on.

Already comparisons have been drawn between the "Fukushima 50" and "Los 33" – the miners trapped in the Chilean mine last year. But the analogy does not fit. In Chile, a nation hoped and prayed for the safety of the trapped men. Here, they look to the workers at Fukushima to ensure their own safety, bringing to mind Churchill's most oft-repeated quotation: "Never... was so much owed by so many to so few."