How bad is it? Depends on which nuclear expert you ask

By the CNN Wire Staff
March 15, 2011 11:48 p.m. EDT

(CNN) -- Experts disagreed Tuesday over just how bad things have gotten at the stricken Fukushima Daiichi nuclear plant in northeastern Japan, but all of them agreed that things could get worse.

An explosion Tuesday at the plant elevated the situation there to a "serious accident," on a level just below Chernobyl, a French nuclear official said, referring to the international scale that rates the severity of such incidents and to an incident 25 years ago in what is now Ukraine. His comments came before a fire was reported Wednesday in the No. 4 reactor building at the Japanese plant.

The International Nuclear and Radiological Event Scale -- or INES -- ranks incidents from Level 1, which indicates very little danger to the general population, to Level 7, a "major accident" with a large release of radioactive material and widespread health and environmental effects.

"It's clear we are at Level 6, that's to say we're at a level in between what happened at Three Mile Island and Chernobyl," Andre-Claude Lacoste, president of France's nuclear safety authority, told reporters Tuesday.