President Carter's crusade against the nuclear breeder reactor resembles the campaign of a few years ago to scuttle the U.S. supersonic transport plans (SST). Superficially, it's a contest of technology against morality. But, ulimately, economics will decide the issue: if the breeder is too expensive, it will fail.

If this seems too simple, remember what happended to the SST. In the late 1960s, environmentalists assaulted the plane, saying that it was too loud and that - just possibly - it might strip theatmosphere of ozone, which shields the earth from solar radiation.

The aerospace industry and the airlines loudly insisted that the United States needed an SST: the British and the French were building one, and if U.S. manufacturers didn't reproduce a rival, U.S. airlines would be compelled to buy abroad.

Time has vindicated Congress's decision to scrap the SST, but mostly because supersonic travel has emerged as an economic monstrosity. Having poured $4 billion into their Concorde, the British and French will probably produce only 16 of the $60 million planes. The Concorde failed simply because it is too expensive for both airlines and passengers. If it had proven otherwise, the pressure for the United States to emulate would have been enormous.

To compare the breeder reactor to the Concorde is not to suggestSamuel regularly writes about economic affairs for the National Journal, from which this article is reprinted. that these technological enterprises have equal significance. They don't. By contrast with the breeder, the Concorde is a mere toy.

That President Carter used his first veto to try to scuttle the breeder at Clinch River, Tenn., only emphasises the importance of the underlying issues: energy scarcity on the one hand and nuclear proliferation on the other. But the resolution of the breeder controversy may follow the Concorde pattern.

Enthusiasm for the breeder - and there is plenty of it here and abroad - stems from two beliefs. First, that the world needs atomic power because other energy sources will not sustain an expanding global economy, and second, that natural supplies of uranium will be sharply depleted by the year 2000, requiring a reactor that produces were fuel then it cousumes.

Without destroying these beliefs, Carter can no more convince, say, the French to abandon their breeder than he can persuade them to abstain from wine. Nor will the job be any easier with the Japanese, the Germans, the British or the Soviets. Three of these countries (France, Britain and the Soviet Union) already have constructed demonstration plants on the scale of the Clinch River project. By the 1980s, they plan to have commercial plants operating. Unlike the United States, these other countries lack large supplies of natural uranium.

The danger of the breeder, in Carter's view, is that it produces vast amounts of plutonium, which can be fashioned easily into bombs. These is correct. In the hands of small countries, the breeder (coupled with "reprocessing" facilities to separate the plutonium from used fuel rods) would put them in a position to develop a weapons stockpile as an adjunct to a commercial power program.

But it is also correct - as the President's critics contend - that there are other ways to obtain nuclear weapons. For example, covert reprocessing facilities could extract plutonium made in a small research reactor; both the reactor and reprocessing technologies are within the group of many countries.

Moreover, there is no nuclear power cycle that completely eliminates the risk of diverting fuel to weapons. Weighing these realities and their own fears of energy scarcities, foreign powers see Carter's preoccupation with the breeder as either insensitive or silly.

But the breeder is vulnerable. If large supplies of uranium are found, of if the breeder's costs balloon sharply, then the reactor's development will be greatly, possibly fatally, frustrated.

Are these possibilities likely? No one knows, but they are genuine. In the past few years, for example, uranium reserve estimates have increased sharply. It is not pollyannaish to argue (as administration officials do) that higher uranium prices will stimulate more exploration and discovery.

Nor is it silly to suggest that breeder reactor costs could spin out of control. The Clinch River project itself offers an apt example. Originally estimated at $450 million, the reactor is now projected to cost $2.2 billion.

As a demonstration project, its costs cannot be taken as typical, but there is no denying that the breeder poss formidable engineering and metallurgical problems. The breeder's liquid sodium reactor coolant circulates at about twice the temperature as the water coolant in conventional reactors (about 995 degrees Fahrenheit against 540 degrees), creating huge, internal stresses.

More important, the competitiveness of the breeder will depend heavily on the costs of coventional reactors, which in turn, will depend largely on the availability (and price) of natural uranium. Thus, the success of Carter's policy lies very much at the mercy of outside forces.

Privately, administration officials do not expect that U.S. renunciation of the breeder will convince the Europeans or the Soviets to do likewise. The hope is more modest: that breeders will not be exported in large numbers to third countries. But unfavorable breeder economics may accomplish that.

Few countries, developed or developing, can afford to spend a few billion dollars needlessly on reprocessing and on breeders. Indeed, had economics probably would limit construction of breeders in countries that develop them. Even the French are not punching out extra copies of the Concorde for sheer glory.

Against this background, the wisdom of the President's veto of the Clinch River project is ambiguous. If Carter is sustained, it may (as he hopes) take some of the aura of inevitability away from same time, spur the search for technological improvements to non-breeder reactors that improve their efficiency in using uranium. But it may also (as his critics charge) simply put the United States furter behind in developing this technology and, ironically, weaken American bargaining strength in determining what international safeguards should apply. Without a U.S. stake in the breeder, will other countries listen to American wishes?

The issue is not settled. Congress still could override the President's veto or include money for the breeder in an appropriations bill. But, however it comes out, it may be 10 or 15 years before anyone knows whether the decision was right.