The nuclear age in California may end with a whimper and not a bang if critics of the whether any other nuclear power generating plant have their way.

Utility company executives and nuclear power opponents alike agree that the fate of the proposed 1,900-megawatt plant is likely to determine any other nuclear power plant is ever plant is ever built in California.

That's because Sundesert, which the San Diego Gas and Electric Co. and other utilities proposed to build in the desert 200 miles east of San Diego, probably is the most attractive nuclear generating proposal ever considered in the state.

Even its critics say that the power it would provide is badly needed in the San Diego service area. Unlike most nuclear plants in California, it has provoked relatively little local opposition in the near by towns of Palo Verde and Blythe. And again, unlike many proposed nuclear plants in California, there are no known earthquake hazards associated with its construction.

It's one of the best opportunities for the proponents of nuclear power," acknowledges Huey D. Johnson, secretary of resources in Gov. Edmund G. (Jerry Brown's cabinet. Even so, Johnson believes there are better ways.

"Nuclear shouldn't have anything to do with our destiny," Johnson believes "It's time to get on with the business of alternatives."

Johnson has a voice but no vote on the California Energy Resources Conservation and Development Commission, whose five members were appointed by Brown. Three of the members, including chairman Richard L. Maullin, are considered skeptical of nuclear energy with one member pronuclear and the opinion of the remaining member unknown. The commission must decide whether to allow Sundesert to be built.

After lenghty study, Maullin recently issued a report recommending first-stage approval of Sundesert. However, the conditions he attached make critics believe the project will never be built.

The conditions include a requirement that the utilities involved file for alternative power plant projects at the same time, including the development of geothermal power, the renovation of existing oil-fired units and the construction of a new oil-fired plant which could be converted to coal gasification by 1990.

If the commission accepts this finding, when it meets here Dec. 21, it would mean that Sundesert could not go forward until the utilities had demonstrated that alternative proposals are impractical. Commissioner Gene Varanini wants to go even further and require San Diego Gas and Electric to make detailed cost comparisons between a nuclear plant and an oil-fired plant.

Such conditions could delay Sundesert for two to three years and in effect force San Diego Gas and Electric to turn to an alternative source that might more quickly win commission approval.

In response, the utility has decided to wage an all-out fight for approval of the $3 billion nuclear plant without considering alternatives.

"In our judgment these other alternatives do not exist," says Frank DeVore, the utility's vice president for governmental relations.

DeVore points to substantial local opposition to the use of coal, which would have to be imported into California. He says that technology is insufficiently advanced for the extraction of geothermal power from the hot brine of the Imperial Valley. (California already uses 600 megawatts of geothermal power, but most of it comes from the hot steam of The Geysers area nearly 500 miles to the north of the Sundesert site.)

An oil-fired plant is technologically possible but faces environmentalist objections. DeVorce observes that two major oil-fired plants in the San Diego company's service area already are under abatement orders from the county air pollution district. Based on this experience, he says, it is unlikely that an oil-fired plant, while acceptable to nuclear foes, could win the necessary local clearances.

Alan D. Pasternak, an engineer who is the only open advocate of nuclear power on the energy commission, argues that the anti-nuclear majority is flying in the face of President Carter's national energy proposals for the conservation of oil.

"The California energy commission's approach to the energy crisis is based on electricity, which is not a primary energy resource," Pasternak said recently in testimony before a legislative committee. ". . . The President's plan seeks conservation of oil, while California policy ignores oil and the other primary resources and emphasizes conservation of electricity."

This contradiction is not necessarily an accidental one. Gov. Brown, who draws distinctions whenever he can between his administration and President Carter's, has advocated reliance on solar energy and geothermal power and questioned the widsom of relying on nuclear energy.

Complicating the issue are three bills approved last year by the legislature in the interests of nuclear safety. They prohibit the state energy commission from licensing any new nuclear power plants until the commission has found that technology exists for reprocessing and disposal of nuclear wastes.

State Sen Alfred E. Alquist of San Jose, chairman of the Senate Public Utilities, Transit and Energy Committee obtained an opinion from the legislative counsel that these bills are unconstitutional because the nuclear waste issue has been pre-empted by the federal government. But in the absence of a court test they remain in force, and Commissioner Varanini warned this week that San Diego Gas and Electric is "proceeding at its own risk" on the waste disposal issue.

"I'm responsible for the disposal of nuclear wastes in this state," says Resources Secretary Johnson. "I don't want any nuclear waste to be responsible for."

The way things are going in California he is likely to get his wish.

Recently, discovery of a new earthquake fault caused the federal Nuclear Regulatory Commission to order the shutdown of a nuclear plant near Pleasanton in the San Francisco Bay Area.Two other plants in the state remain in operation but one of those, Rancho Seco near Sacramento, has been shut down intermittently because of technical difficulties. Such once-promising proposals as a massive nuclear plant proposed by the Los Angeles Department of Water and Power in the San Joaquin Valley have been stalled by local objections.

Overall, nuclear energy appears on the way out in California and Sundesert is likely to be the determinant.

As one of the executives from a Northern California utility put it last week: "All of us are watching Sundesert. If we can't get this one by the energy commission, we might as well give up our nuclear power."