As far as I know, neither Nobel laureate IPPNW nor GfS is mainstream (by default as organisations being highly critical of the nuclear industry) but AFAIK both consist of radiation experts, and that particular study is a meta-study with focus on Russian-language studies not published before in English (or German). Their report is the main one I used five years ago as source for Chernobyl's Downplayed Victims. However, in the Russian-language studies meta-study category, Chernobyl: Consequences of the Catastrophe for People and the Environment (which I tracked down inspired by some link on ET recently, by das monde I think) is newer, deeper, more comprehensive and more detailed. It contains the 212,000 deaths estimate, but explains that even that is partial, and they add several more sub-sums, including statistical deaths in large populations across the world with low exposure, to arrive at a total of one million(!).

_{*Lunatic*, n.
One whose delusions are out of fashion.}

Chernobyl Cleanup Survivor's Message for Japan: 'Run Away as Quickly as Possible'

Natalia Manzurova, one of the few survivors among those directly involved in the long cleanup of Chernobyl, was a 35-year-old engineer at a nuclear plant in Ozersk, Russia, in April 1986 when she and 13 other scientists were told to report to the wrecked, burning plant in the northern Ukraine.

[...]

She spent 4 1/2 years helping clean the abandoned town of Pripyat, which was less than two miles from the Chernobyl reactors. The plant workers lived there before they were abruptly evacuated.

Manzurova, now 59 and an advocate for radiation victims worldwide, has the "Chernobyl necklace" -- a scar on her throat from the removal of her thyroid -- and myriad health problems. But unlike the rest of her team members, who she said have all died from the results of radiation poisoning, and many other liquidators, she's alive.

[...]

But experts say Fukushima is not as bad as Chernobyl.
Every nuclear accident is different, and the impact cannot be truly measured for years. The government does not always tell the truth. Many will never return to their homes. Their lives will be divided into two parts: before and after Fukushima. They'll worry about their health and their children's health. The government will probably say there was not that much radiation and that it didn't harm them. And the government will probably not compensate them for all that they've lost. What they lost can't be calculated.

[...]

When you were called to go to Chernobyl, did you know how bad it was there?
I had no idea and never knew the true scope until much later. It was all covered in secrecy. I went there as a professional because I was told to -- but if I was asked to liquidate such an accident today, I'd never agree. The sacrifices the Fukushima workers are making are too high because the nuclear industry was developed in such a way that the executives don't hold themselves accountable to the human beings who have to clean up a disaster. It's like nuclear slavery.

[...]

Why did you go back to Chernobyl after getting a thyroid tumor?
Right around the time of my operation, the government passed a law saying the liquidators had to work for exactly 4 1/2 years to get our pension and retire. If you left even one day early, you would not get any benefits.