This reduces the radioactive release to the environment with up to 99%.
This was one of the reasons for the large radioactive release to the environment.
People in Mud Lake said last July that they never knew there had been radioactive releases.
He predicted a "quite small" increase in cancer deaths in future years as a result of radioactive releases.
The work is dirty, with the threat of radioactive releases, and it is expensive.
The size of the radioactive release at Tomsk-7 was much smaller, and while it caused moderate environmental contamination it did not cause any early deaths.
"I think the likelihood of a radioactive release is definitely small," she said, "but I want to be prepared."
There was no radioactive release to the environment.
A meltdown or major radioactive release could put millions of people at risk.
Urquhart has extrapolated from this the likely radioactive release of polonium.