BOSTON (AP) _ Cold fusion equipment used by a University of Utah chemist who claimed to harness the power of the sun in a lab jar didn't produce any nuclear energy, said a physicist at the school who tested the apparatus.

''We did not see a peep,'' said Michael H. Salamon, who measured the nuclear output of cold fusion gear in the lab of Stanley Pons for five weeks.

''There was not an iota, not a sniff, of conventional fusion occurring. We saw no neutrons or gamma rays that could be attributed to a fusion process.''

His findings appear to be another blow to the already widely questioned announcement last March of a revolutionary new source of energy.

But one backer of cold fusion said the new findings fail to prove anything because Pons' equipment was not working properly when Salamon tested it.

Salamon said his measurements, published in Thursday's issue of the British journal Nature, were made at Pons' invitation. He conducted the tests last May and June, about two months after Pons and Martin Fleischman of the University of Southampton in England announced they achieved fusion at room temperature in simple laboratory equipment.

Pons responded, ''It's pretty distressing, because most of the allegations in the paper are not true.''

In a telephone interview Wednesday from Salt Lake City, Pons said the physicists ignored energy cells that were producing large amounts of heat and instead set up their monitoring equipment to check ones that were making only low amounts. He said the sensors were also placed at an angle that missed evidence of nuclear activity.

Pons said Salamon's team was in the laboratory ''for political reaons.''

''They were embarrassed by this,'' he said. ''They were embarrassed that a chemist had fallen into a nuclear reaction so simply. Their outside colleagues were putting tremendous pressure on them.''

Pons also accused Nature of trying to undermine his work by publishing negative studies while ignoring supporting evidence.

Others, however, viewed Salamon's paper as one more reason to be skeptical.

''It's another nail in the coffin,'' commented Ronald Parker, director of the plasma fusion center at Massachusetts Institute of Technology. ''They did a very careful search for fusion effects, and they came up empty.''

Fritz G. Will, director of the state-funded National Cold Fusion Institute at the University of Utah, said small changes in experimental conditions, including humidity, can affect whether or not Pons' fusion cells produce heat.

At the time Salamon checked the equipment for signs of fusion, Will said, ''experimental conditions prevailing in those experiments were not suitable to finding the phenomenon.''

Pons' equipment consisted of a palladium electrode wrapped in platinum and immersed in a flask of deuterium oxide, or heavy water. When electricity is run through the metals, proponents say, deuterium atoms fuse, giving off more heat than the energy put in.

Nuclear fusion powers the stars. Traditionally scientists have believed that fusion could occur only at extremely high temperatures. Cool, small-scale fusion would provide a convenient, limitless source of power and be one of the greatest scientific discoveries of all time.

Pons' and Fleischman's seeming breakthrough was questioned when researchers in other labs had trouble duplicating their results. While many scientists say they doubt cold fusion exists, experiments continue at labs around the world.

Cold fusion, if it occurs, is likely to produce heat, extra tritium and specific patterns of neutron and gamma ray releases known as nuclear signatures.

''Nintey-five percent of those researchers who have tried to find anomalous effects, whether excess heat or nuclear signatures, have come up empty- handed,'' Will said.

''The mere fact that a large percentage of scientists have failed to confirm does not mean that the phenomenon that has been confirmed by 5 percent is incorrect. The burden is on those who haven't found it to change their experimental conditions so they find it also,'' he said.

Will said 20 labs experimenting with cold fusion have produced excess heat, about a dozen have found large tritium counts and ''at least a handful'' have seen signs of neutron release.

Salamon set up sensors for gamma rays that would be discharged when neutrons produced by the nuclear process hit the water bath that surrounded the fusion cells.

Salamon said he had planned to study Pons' records of heat produced by his fusion cells to see how they matched up with the detection of gamma rays. However, he said Pons later refused to turn over the records.

During the five weeks of study, Salamon's equipment was out of service for a two-hour period because a lightning strike knocked out the power.

Salamon said Pons later told him that the fusion cells produced excess heat during this time. However, Salamon said he could find no residual signs of a neutron burst that would have lingered for several days.