General Public Utilities Corp., owner of Three Island nuclear power plant, said yesterday it is seeking federal help in paying the cost of cleaning up the damaged reactor.

GPU President Herman Dieckamp told the Senate nuclear regulation subcommittee that if negotiations with the Energy Department are successful, the help would be in the form of federally funded research projects that would treat the March accident as an educational experience.

"This is an important opportunity to add to the nation's nuclear expertise," he said. He said he hoped "for a fairly significant participation by the government and by the electric power industry itself."

While making it clear to reporters after the hearing that he would be delighted to have any direct aid from the government or even sell it his damaged goods, Dieckamp stressed that he was not negotiating for a bailout such as the help the Chrysler Corp. is seeking from the government.

Instead, he said, DOE already plans to fund research that could be conducted either at Three Mile Island or on materials from the site for which the government would pay GPU access fees and material costs. Dieckamp cited development of decontamination methods, studies of hot core behavior and removal and experimental work on damaged fuel pellets as examples. b

Cleanup is expected to cost $400 million and GPU is insured for $300 million in damage to its property. "Every little bit helps," Dieckamp said.

Herbert Feinroth, chief of DOE's reactor evaluation branch and the negotiator of the arrangement, said he had no idea how much would be spent but that it would be "nonsubstantial."

"It's not giving them money, it's a convenient way of learning more about reactor safety," he said. "We're not even condisering direct grants."

Dieckamp noted that Virginia Electric and Power Co. has $5 million arrangement with DOE to provide one of its damaged steam generators for study. "That's a possible parallel, " Dieckamp said.

Asked by Chairman Gary Hary (D-Colo.) whether GPU would guarantee the Three Mile Island cleanup should the operating utility, Metropolitan Edison Co., a GPU subsidiary, go bankrupt, Dieckamp said, "I can't answer that. It's very complicated . . . we've already spent $100 million."

The Pennsylvania Utilities Commission is expected to decide next month questions of ratepayers' share in the costs and that will be crucial in the company's financial future, Dieckamp said.

He noted that some consideration is being given to converting the damaged reactor from nuclear to coal, once the site is cleaned up.

Although the power plant's steam generators and turbines might be convertible to the use of coal, the resulting hybrid would be "far from optimum . . . perhaps not very productive," according to Richard Wilson, who is directing GPU's recovery effort. He told the subcommittee that one of his staff's main worries was that Nuclear Regulatory Commission regulations on what must be done might change during the cleanup.

Harold Denton, chief of the NRC's reactor regulation office, confirmed that. "The question is to what extent we should do better than the normal regulations" in requiring a careful cleanup at Three Mile Island, he said. The NRC is leasing 1,700 square feet of office space in Middletown, Pa., to oversee the cleanup, Denton said.

A memo from the subcommittee's investigatory staff report on the scope of the cleanup reveals several new facts. Highly contaminated water is deepening in the reactor containment building at one-half to one inch a month and is probably "flocculent in appearance, gelatinous, dark green [in] color," the report said.

Standard methods of decontamination may not work with such water, the report said.

Before that begins, highly radioactive krypton gas has to be removed from the containment's atmosphere, but the NRC has no guidelines for handling the gas. The worst problem, which Denton called "a very interesting technical question," is removal of the hot core itself. Not only will it require special tools and untested procedures, but there also may be no place to put it afterward.

"No doubt it will be held onsite until the country comes to grips with the problem of these wastes," Denton said.

Dr. Judith Johnsrud, codirector of a nonprofit Pennsylvania group called the Environmental Coalition on Nuclear Power, asked the senators to require a full review of all cleanup plans under the National Environmental Protection Act.