Tuesday marks the 30th anniversary of the Chernobyl explosion - the biggest nuclear disaster in history.
Hundreds of thousands of first responders (soldiers, firefighters, scientists and engineers) were sent to the site to contain the fallout, and 30 years later, the survivors are still struggling with the consequences to their health.
Elena Casas reports from Moscow.
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In the early morning of April 26th, 1986, a huge explosion shook the fourth reactor at Chernobyl nuclear power plant, flinging out radioactive debris from the reactor's core.
The fire burned for 15 days … and the firemen fighting it received up to 200 times a lethal dose of radiation.
Nikolai Ostretsov was a senior nuclear scientist at the site.
SOT Nikolai Ostretsov, nuclear scientist
"The people arriving there for the first time didn't understand the danger, especially the firefighters who initially thought they were extinguishing regular fire - that's why died within a week."
Soviet authorities were afraid the leaked radioactive material would spark an even bigger explosion - so hundreds of thousands of soldiers were sent to the site to clear up the nuclear debris.
SOT Nikolai Ostretsov, nuclear scientist
"We were well aware of the danger in what we were doing. but the soldiers were in a very bad situation. They worked in most contaminated areas and did all the dirty work."
Ostretsov has himself suffered heart problems and cancer he blames on the radiation.
More than 800,000 soldiers and firemen risked their lives to clean up the fallout.
Victims' groups say one in five of them had died young by 2005 - and 90% of survivors suffer radiation related diseases.
Under the Soviet Union, the survivors were promised lifelong benefits.
Lawyer Vyacheslav Kitayev was himself a first responder - now, he helps others fight for their legal rights.
He says a series of laws passed in recent years has reduced their entitlements - in 2004, they lost the right to free health care and public transport, while later rule changes have capped their payments.
SOT Vyacheslav Kitayev, lawyer and former Chernobyl first responder
"There was also a law on the rights of military servicemen, when they were prohibited from receiving compensation for the harm they've incurred calculated from their official salary. The Constitutional Court has ruled three times that this is unconstitutional."
Kitayev says disabled Chernobyl survivors cannot afford the medication they need - with some receiving just 15 dollars a month from the state.
30 years on, they continue to fight for the compensation they were promised