India's Canadian-built but locally run nuclear power reactor in the Rajasthan Desert broke down 19 times last year. When it works, it produces only about half the amount of power it should.

In Madras, a totally Indian-built reactor is scheduled to begin operating this year after 18 years of construction, reportedly 13 years longer than expected.

Japan, on the other hand, tosses up nuclear power reactors in five years or less.

These are some of the high costs of India's national policy of going it alone in the nuclear energy field, a decision forced on the country in 1974 when it exploded a nuclear device. Although India dubbed the test "a peaceful nuclear explosion," most of the world called it a precursor to an atomic bomb.

Yet, for India, whose economic and defense credo has been self-reliance since it gained independence 34 years ago, going it alone provides a giant plus that outweighs all the disadvantages. It enables India to call itself number one among the developing nations in nuclear power and provides a major boost to a country trying to recast its image from that of a beggar unable to feed starving millions to an up-and-coming Third World technological power.

"India," boasted Atomic Energy Commission Chairman Homi N. Sethna, "is the country to have full control over the nuclear fuel cycle apart from the major nuclear countries such as the United States, the Soviet Union, France and Great Britain."

Now India, which lost Canadian help in building reactors when Ottawa accused it of siphoning off technology and materials for its 1974 explosion, may be forced even further into nuclear isolation by negotiations that started here yesterday with the United States on the continued supply of enriched uranium for the American-built power reactor at Tarapur.

In rock-hard positions that have barely changed in years, India insists that the United States is obligated to supply the uranium under a 1963 agreement between the two nations. Washington says, however, that a congressional act passed partially as a result of India's 1971 explosion bans the sale of nuclear materials to nations that refuse to allow full international inspection of their atomic facilities.

India calls this discriminatory and, although some of its nuclear facilities, such as Tarapur, are under international safeguards, it refuses to allow inspections of installations it has put up without outside help.

One more round of talks in Washington is planned in what appears to be the final step toward ending the agreement. In describing the current talks, Indian spokesman J. N. Dixit said there was no discussion of the United States sending more fuel to Tarapur even though Congress last year authorized the shipment of another load.

It appeared, however, that neither side wants to precipitate the break by any rash nation. Dixit went out of his way to emphasize the long friendship that, despite present strains, remains between India and the United States. At one point he refused to take a question and chastised an Indian reporter who characterized President Reagan's policies as having "double standards."

Yet there are still major differences on the way the Tarapur agreement should be buried. The United States wants the safeguards to continue on the spent fuel from the Tarapur reactor, which can be reprocessed by India into plutonium that could be used for nuclear weapons. New Delhi, on the other hand, said if the agreement is ended it can do what it wants with the fuel.

The question has become an issue of national pride, and what is seen here as U.S. refusal to sell nuclear fuel to a fellow democracy is contrasted against the supplying of sophisticated F16 fighter-bombers to Pakistan, which is run by a martial-law government. Pakistan also has been accused of trying to develop nuclear weapons.

In the heat of Indian emotions, the truth has become blurred. Even India's Ministry of External Affairs, usually punctilious in its choice of words, persists in elevating to treaty status the executive agreement for the United States to sell the fuel.

Under international law, a treaty takes precedence over domestic legislation while an executive agreement does not.

Moreover, while India made the first overtures late year about canceling the agreement in the interests of improving relations with the United States, it quickly shifted the onus to Washington once the U.S. government accepted.

Indian officials insist they will be able to operate Tarapur even without further shipments of fuel from the United States. They have picked up the technique of making a mixed oxide fuel, developed in Europe and the United States in the 1960s for possible use in breeder reactors, as a substitute for enriched uranium.

"Its behavior is well understood. There's no reason why India can't use it," said one Western observer of Indian nuclear efforts.

Nonetheless, one Indian scientist closely connected with this country's nuclear establishment said unexpected problems have developed in making the mixed oxide fuel and India may not be ready to switch from enriched uranium when the U.S. supplies are used up in about a year.

In that case, India is likely to obtain enriched uranium from the Soviet Union, its major arms supplier, reported G. K. Reddy, the well-informed New Delhi correspondent of the Madras daily, The Hindu.

Thus again it appears that India persistently and proudly has decided to go it alone, with the possibility of temporary Soviet help, despite the costs that Western experts believe have been great in the nuclear field.

"Self-reliance," said one well-informed scientist, "has resulted in a heavy financial cost, considerable construction delays and many operational problems."

Much of the Indian scientific effort, added another, "consists of reinventing the wheel -- discovering technology that is readily available elsewhere."

As a result, the program continually runs behind government projections, despite a desperate shortage of power in the country. Its goal of generating 2,700 megawatts of nuclear electricity by 1980 was never reached and the target date was extended to 1984. Observers believe it is doubtful Indian will even reach that goal.

India generates 3 percent of its electric power with nuclear plants and by the year 2000 wants to increase nuclear energy production to meet 10 percent of its needs. But that projection also is considered doubtful.

By way of contrast, South Korea, which imports all its nuclear knowhow, confidently expects to generate 11,000 megawatts of power -- 40 percent of its total production -- in nuclear plants within 10 years.

Nonetheless, there are no signs that India plans to turn away from its goal of becoming a nuclear power on its own.

"I'm a great believer in self-reliance. Buying technology can be stifling," said Raja Ramana, the director of India's sophisticated Bhahha Atomic Research Center, near Bombay.

Sethna, the Indian Atomic Energy Commission chairman, said that "when you buy technology you have to buy under all sorts of conditions. We just don't like that."

There is no question that India, which ranks third in the world behind the United States and the Soviet Union in its pool of technically trained manpower, has the top-flight scientists needed to make an atomic energy program work.

But the campus-like setting of its nuclear research center is only a tiny part of India, where more than 200,000 villages have no electricity at all and a space rocket was delivered to the launch pad on a bullock cart.

Ramana said his biggest problem is the lack of an industrial base to supply the precise fittings and tubing needed for atomic reactors.

Furthermore, generating nuclear power is a tremendously complicated technical challenge, one that few other developing countries care to take on by themselves. It is, one expert said, five times as difficult to set up a nuclear power reactor as to build an atomic bomb.

"They are really trying to do the most difficult thing first," said a Western nuclear expert of the Indians. He said they are just beginning, and it is too early to tell if they will succeed or fail.