A federal safety experts has warned the Nuclear Regulatory Commission that flaws in the design of the casks used for shipping naval nuclear reactors could turn the reactors into live neutron bombs in an accident.

Ronald G. Glary, as structural engineer in the NRC's transportation branch, warned that if the 250-ton metal cask were damaged during the shipment on its specially constructed railway car, the result could be an intense burst of radiation from the reactor's core, similar in effect to a neutron weapon.

NRC experts acknowledged that if Clary's computations were correct and water entered the ruptured cask the reactor would reach criticality, the mass of nuclear material needed to support a chain reaction. The experts said such a possibility is "a long shot," but the NRC said it planned to give Clary's concern," said Robert M. Bernero, assistant director for material safety standards. Last year, after Clary filed a memo noting 15 potential regulatory deficiencies connected with the reactor casks, Bernero was assigned to head a panel of experts reviewing the memo.

Most of Clary's concerns were dismissed by the panel as not valid, but two were deemed worthy of additional study - his contention that NRC regulations fail to cover certain types of accidents that could rupture the nuclear casks and his concern that NRC regulations do not deal with vibration problems that could weaken the shipping vessels.

"The real question he is raising is whether the regulations governing these casks are designed to deal with a reasonable set of accident possibilities," Bernero said.

The review panel's report, filed late last year, notes that neither concern raised by Clary is currently covered by NRC licensing regulations. NRC officials said no action has been taken since then that would alter the shipping regulations. A study under way on the vibration problem will probably take a year, they said.

Each 50-foot cask is composed of two cylindrical containers joined by a bolted flange. One section contains the fully-assembled core of a nuclear reactor to power a Navy submarine; the other contains the reactor's control rod operating mechanism. The core is shipped with the control rods inserted and held down by latches.

Clar's comments on the casks were part of a case file he submitted last week to the NRC in opposition to a dismissal move against him. He said that safety issues raised by staffers within the NRC are frequently supressed by managers, and thatn "whistleblowers" like himself are victims of harassment and intimidation.

A copy of the case file was made available to The Washington Post.* In the file Clary charged that the NRC issued a certificate of compliance to the Department of Energy's division of naval reactors despite objections from some staff members who felt the casks may be unsafe. The NRC routinely licenses containers used by the Navy to transport radio-active materials.

A Navy spokesman said yesterday the precise location of the fuel manufacturing facilities for the nuclear submarine reactors is classified. The reactor cores are assembled at facilities under Department of Energy contract and shipped to naval shipyards by rail.

The Navy spokesman identified the following shipyards as refueling locations for nuclear submarines: Portsmouth Naval Shipyard Kittery, Marine; Norfolk; Va., Naval Shipyard; Charleston, S.C., Naval Shipyard; Puget Sound Naval Shipyard, Bremerton, Wash.; Mare Island Naval Shipyard, Vallejo, Calif.; Pearl Harbor, Hawaii, Naval Shipyard; Newport News, Va., Shipbuilding and Drydock Co., Ingalls Shipbuilding Division, Pascagoula, Miss.

In a statement yesterday the Navy said it considered the casks safe because they met the safety requirements of the NRC regulations as well as those of the departments of Transportation and Energy. The Navyhs statement did not comment on Clary's allegations that the regulations were inadequate.

Clary first outlined his concern about cask safety in a Nov. 4, 1977, memo to C.E. MacDonald, head of the NRC's transportation branch."The memo said some of the casks were being licensed without scientfic information.

In an accident, Clary said, the cask could topple onto rough or uneven ground. While NRC regulations call for the casks to withstand a 30-foot drop onto "a flat essentially unyielding horizontal surface," Clary warned that they might not withstand the multiple jarring from a drop onto an uneven surface.

He warned that in such a highspeed impact the cask could break open at the center flange, causing control rod ejection. If the accident occurred where water could enter the ruptured cask, the result would be the instant buildup of raidoativity, Clary warned.

"If the core went critical in one of those things," Clary said recently, "you wouldn't feel a thing. There would be no symptoms, you'd just drop in your tracks."

Clary said the accident "would make the problems they had at Three Mile Island look like a Sunday school picnic.

Charles Marotta, a senior shielding and critically engineer for the NRC, said in an interview that, while Clary's concern about the ruptured cask was "a long shot," the scenario could occur under the right combination of circumstances.

Marotta said that the reactor would probably give out one large pulse of dangerous radioactivity in the case of such a criticality, but would eventually be safe to handle. If no water seepd into the cask, he said, "you could walk in and just pick up the pieces. There would be no danger of radiation at all." CAPTION: Picture, Ronald Clary of NRC with case file on hazards of transporting Navy's reactors.