After canceling nearly all the shah's arms deals with the United States and other foreign countries, Iran is now on the verge of scrapping at least $34 billion worth of major civilian projects - including four nuclear power stations - that are already under way or on the drawing board.

In the latest move to dismantle the deposed monarch's grandiose development plans and turn the country's economic priorities around, the new head of the Atomic Energy Organization of Iran has called for the cancellation of two nuclear power plants that are more than three-quarters complete near Bushehr on the Persian Gulf.

Though the government has not yet officially terminated the contracts, the statements by Fereidun Sahabi appears to doom prospects that construction work on the plants will resume. The work ground to a halt during the revolutionary turmoil last winter when hundreds of foreign engineers left the country.

The two 1,200-megawatt units were being built by West Germany's Kraftwerk Union under a 1976 contract. They were to have been the first of some 20 nuclear power stations to be installed in Iran by 1994.

The rest of the program, including two French plants under construction at a site on the Karun River in south-western Iran, has already been scrubbed.

So have other multibillion-dollar projects ranging from an entire "city center" in Tehran, a new Tehran airport and a steel mill near Isfahan - all in various stages of planning or site preparation. Other major projects on which construction already had begun are still technically "under study" by the Islamic republic's provisional revolutionary government, but several of them are now considered dead.

These include a $3 billion gas pipeline from the Persian Gulf to the Soviet Union, a $2.4 billion six-lane highway from Tehran to the Gulf port of Bandarshahpour and a $1.3 billion subway system for the capital.

Iran has already spent several billion dollars on these and other projects likely to be written off, and stands to see huge investments come to nothing. To push them through, however, would entail even greater spending, the return of legions of foreign experts and renewed emphasis on big remote projects - all politically unacceptable under the new government.

The biggedt example of a major project going to waste is the Bushehr atomic power complex. Spurred by Shah Mohammad Reza Pahlavi's dream of running a modern industrial state on nuclear energy after the country's oil wells run dry by about the turn of the century, Iran bought two plants each from West Germany and France, signed letters of intent for four more German units, and opened contacts with French and American firms for another 8 to 10 plants.

Iran already has sunk more than $3.1 billion into the Bushehr plants, and work is now about 77 percent complete. Yet so great are the remaining problems in finishing and operating them that one Iranian energy expert has suggested that authorities would do better to turn the nearly completed reactor vessels into grain silos.

After months of study, Iran's new atomic energy chief has also come around to the view that the government should cut its losses and cancel the plant.

"Apart from technical difficulties," Sahabi said in a Tehran newspaper interview, "we are facing soaring costs which were never predicted when these agreements were first signed."

Although he considers economic factors and insufficient manpower enough to justify abandoning the project, Sahabi also cited the recent nuclear accident at the Three Mile Island plant near Harrisburg, Pa.

"When one thinks that such accidents can happen in countries with advanced technological capabilities, one has to be very careful about using [nuclear] power plants" in a country that lacks such expertise, Sahabi said.

Faced with the dilemma of having already made a huge investment in the Bushehr plantbut being unable to complete and operate them without more massive infusions of cash and another influx of foreign help, Iranian authorities have been pondering the fate of the power stations since the February revolution.

In recent weeks, however, Iranian officials started leaning toward cancellation.

"With our lack of technology and the problems involved with nuclear power plants, at this time it is not good to have them," the atomic unit's executive, Mansour Ruhi, said recently.

The debate has been fueled by large cost overruns for the plants. Originally the price tag for the twin units was some 8 billion West German marks ($4.16 billion at the current exchange rate) with an additional 3 billion marks ($1.56 billion) for fuel deliveries over a 10-year period.

But in a study last fall, Bijan Mossavar-Rahmani, a research fellow with the Rockefeller Foundation, put the plants' costs at 13.2 billion marks ($6.8 billion), including auxiliary facilities, cost escalation and interest during construction and "indirect costs."

In addition, he said, other capital requirements not included - such as consultants' fees, training, high voltage transmission lines, customs exemptions and "other costs not normally entailed in construction of alternative power generating facilities" could run into several billion dollars more.

According to Mossavar-Rahmani, the entire Iranian nuclear program of 20 reactors was likely to cost much more than the $30 billion envisaged - possibly three times as much.

While dismantling Iran's nuclear power plant program, the authorities will have to decide what to do with some of the shah's other atomic energy investments aimed at guaranteeing fuel supplies for Iranian reactors. Iran has purchased about 28,000 tons of uranium that it now cannot use.

One aspect of the shah's nuclear program that officials intend to pursue, however, is exploration for uranium in Iran.

"Uranium is one of the resources we have to evaluate," said Ruhi. "If we don't use it ourselves, we can always market it abroad."

Two years ago Iran launched a $300 million, 10-year exploration program using aerial surveys with sophisticated detection equipment. A French, Australian and West German consortium was awarded the contract.

With a few major exceptions, the new regime seems determined to finish nonnuclear projects on which massive amounts of money have already been spent and whose construction is well along. Most of these projects are for conventional power plants, roads, railways, or port facilities, and the contracts are generally smaller.

The biggest project on this list is the Iran-Japan Petrochemical Co. complex at Bandarshahpour on the Persian Gulf. Despite cost runups, it has been given the go-ahead by Ayatollah Ruhollah Khomeini, the Islamic republic's de facto chief of state, largely because it is 85 percent complete.

Critics complain that while it was originally supposed to cost $1.8 billion, the complex will probably end up costing $3.2 billion before it is finished.

Another large project facing much the same problem with its eventual production is the Sarcheshmeh copper mining and processing complex in southeastern Iran.

In the final stages of construction by a consortium that includes Anaconda and Parsons-Jurden of the United States, the project stopped during the revolution as did most others, and it is expected to exceed its $1.6 billion price tag at completion.

A $400 million housing project, in which Starrett Corp, of the United States was building 15,000 apartment units west of Tehran in partnership with French and Israeli firms, is likely to be completed with new contractors, government sources said.

Construction of a steel mill with capacity of $2.5 million tons per year is to go ahead with the same contractors, which include Kaiser and Swindell Dressler of the United States.

In addition to the four nuclear power stations, major projects suspended and facing cancellation include;

A $2.4 billion highway from Tehran to Bandarshahpour, sections of which have been awarded to Idaho's Morrison-Knudsen and a French firm.

A $1.2 billion airport 25 miles south of Tehran designed by the New York architectural firm, TAMS.

A $1.4 billion electrified railway from Tehran to Tabriz designed by Britain's Transmark.

The $2.6 billion "Shahrestan Pahlavi" Tehran City Center planned by Britain's Llewellyn-davies.

A $1 billion-plus telecommunications project awarded to American Bell International.

A $1 million ton per year steel mill near Isfahan contracted to British Steel Corp. and worth $1.1 billion.

The $3 billion IGAT 2 pipeline to deliver natural gas to the Soviet Union.