The operations chief at Three Mile Island testified yesterday that he ordered the release of radioactive gases into the atmosphere because he feared an even greater nuclear accident then the one at the plant March 28.

Supervisor of Operations James S. Folyd told the commission investigating the accident for the White House that if he had not ordered the release of radioactive xenon, krypton and iodine form water storage tanks, the radioactivity could have built up to where the water would have been "too hot" to use as a last-ditch method of cooling the damaged uranium core.

"If there were one way to hurt the public, it would have been through a core melt," Floyd testified. "As long as I had that source of water in back of me, I could stop a core melt. It was my choice to vent those gases to protect my water source."

Folyd explained that waste cooling water contaminated by contact with the damaged fuel core had been stored in what nuclear engineers call "makeup tanks," in emergencies to supply cooling water to "makeup" for water that is boiled off by the heat of the reactor. Floyd said he ordered the radioactive gases dissolved in the waste water to be "vented" into the atmosphere to prevent their buildup in the tanks.

"It was the only way to get rid of that gas - to open that vent and keep it open," Floyd testified. "If those tanks got too hot, I'd have to order them closed and lose all that water. I had a choice of damaging the public by releasing the gas or doing worse damage in the event I needed that water to prevent a core melt."

Floyd said he gave the order to keep the vent valve opened in the makeup tanks with the approval of the Nuclear Regulatory Commission. The NRC's representative at the Three Mile Island plant in the first days of the accident challenged that statement yesterday.

"That's not how I understood it," the NRC's Charles Gallina said. "It was my understanding the licensee (the plant operator) said we were going to transfer gases from one tank to another and that the radioactive releases occurred through leaks in the transfer.We had no knowledge they were purposely gas."

Floyd's order to vent the radioactive gases also was challenged by Anne Trunk, the only member of the Kemeny commission who lives in Middletown, Pa., where the plant is located. Trunk said she wanted to know why Middletown residents were not notified in advance that radioactive gases would be vented into the atmosphere.

"Our plan was to advise the state and it was their responsibility to notify local communities," Floyd replied. "Trying to explain what 13 millirems per hour meant to local communities would not be my idea of a fun time."

"it wasn't a fun time." Trunk snapped, "for the parents of schoolchildren in Middletown either."

"There's a tremendous need for public education in this area," Floyd public education in this area," Floyd said apologetically. "What I meant was that we were all very tired and to call somebody in the middle of the night and say, 'Hey, there's 13 millirems over your school right now . . .' - that would have been difficult to do."

Folyd seemed to surprise the 12 commissioners when he said he didn't show up at Three Mile Island until March 29, the day after the accident. He said he spent March 28 at the Babcock & Wilcox plant in Lynchburg, Va., where the nuclear power station at Three Mile Island was designed and built.

The operations supervisor said that, based on his talks with Babcock & Wilcox engineers in Lynchburg, he figured there must have been significant damage to the uranium core on the first day. He said he was "shocked" at Three Mile Island the next day when he realized no one else thad reached that conclusion.

"I didn't tell anybody what I though," Floyd said. "I figured it was history at that point."