The Nuclear Regulatory Committee was warned yesterday that radioactive water is leaking out of the containment building at Three Mile Island at such a rapid rate that in 30 days it will overflow tanks where it is being stored.

Pipes that carry contaminated water out of the containment building are leaking 1,200 gallons of water a day into an auxiliary building outside the containment, where some storage tanks are already full. A 110,000-gallon tank that was installed in the auxiliary building after the March 28 accident will be filled in 30 days, the NRC was told.

NRC officials are concerned about the potential overflow because all the options for dealing with it either would take too long or would pose fresh problems.

Staff members told the five-member NRC that it must decide in the next two weeks how it wants to get rid of the contaminated water. It can decide to install additional storage tanks, it can start sooner than planned a process to remove the radioactivity from the contaminated water or it can begin to pump contaminated water into the containment building of the undamaged reactor alongside the reactor that was shut down by the March 28 accident.

"We don't want to do that because the piping that carries water into the containment at the undamaged Unit One also pumps uncontaminated water into the Susquehanna River," the NRC's Edson Case said. "Since we're under a court order not to pump any contaminated water into the river, we'd like to stay away from that option."

The leak that is forcing contaminated water into the storage tanks is from pipes where radiation levels are still so high that they pose a health hazard to maintenance workers.

While additional storage tanks could be installed to handle the water, Case said it might take too long to get the tanks put in and test their pipes for leaks.

The final option is to start "ahead of schedule" a system to remove the radioactivity from the contaminated water. This system is capable of decontaminating 10,000 gallons a day, Case said, but the NRC feels the operators of the system need more training.