Experts Fear Alarming Crack in Reactor Pool Engineers may face unprecedented nuclear problem By Rob Quinn, Newser Staff Posted Mar 18, 2011 2:00 AM CDT Updated Mar 18, 2011 3:01 AM CDT 4 comments Comments This August 2010 picture shows a fuel storage pool inside the Fukushima nuclear complex. (Getty Images) (Newser) – The situation at Japan's stricken Fukushima Dai-ichi nuclear complex may be even more dire than realized, according to American nuclear experts. Authorities at the Nuclear Regulatory Commission suspect that a crack or hole has developed in the floor or wall of a spent fuel pool at the complex, which will thwart efforts to refill the pool with water and prevent dangerous levels of radiation from escaping. The Los Angeles Times explains that unlike the reactor itself, the reactor pool does not have a containment vessel, meaning radioactive gases and particles can more easily escape into the environment if the pool's 130 tons of uranium fuel start to burn. The assessment is based on information provided by US contractors who were inside the plant at the time of last week's earthquake. If the No. 4 reactor pool is cracked, engineers will face a problem that has no precedent and no obvious solution, according to a physicist with the Union of Concerned Scientists. "My intuition is that this is a terrible situation and it is only going to get worse," he said.