In the worst accident of the nation's atomic bomb tests, federal officials concentrated on allaying the public's fears rather than protecting people from the hazards or radioactive fallout, according to newly released federal documents.

The records show that while officials warned some Utah residents to stay indoors after an hour's exposure to heavy fallout, others were not warned and officials declined to monitor milk for radioactive contamination.

Moreover, other documents show that when grazing sheep died soon after the accident, an Atomic Energy Commission employe expressed the fear that if sheep deaths were linked to radioactive fallout, "the purse strings" for future weapons tests in the United States might be tightened.

The accident occurred on May 19, 1953, when the wind shifted at the time of test blast "Harry," one of the "dirtiest" nuclear bomb tests among the 80 or more weapons detonations between 1951 and 1962.

As result, St. George, Utah, was exposed to more radioactive fallout than has ever been measured in any other populated area -- even Japan. Officials estimate that perhaps more than half of the radiation dumped on the area in over a decade of testing came from Harry.

But exposure to radioactivity, which can cause leukemia and cancer, was not apparently confined just to local residents. Most of the milk produced in the area was shipped to Las Vegas.

In following years, Utah showed marked increases in cases of childhood leukemia, thyroid cancer and birth defects. Some residents who were exposed to radiation on the day of the blast later developed cancers.

While the precautions taken on May 19, 1953, have been publicly known for 26 years -- many cars were blockaded and washed down, and children kept indoors during school recess -- another dimension of government behavior emerges in the documents.

In a remarkably candid account of his activities that day, an unnamed radiation monitor described his reluctance to test and, if necessary, impound contaminated milk.

Harry was detonated in Nevada from a 300-foot tower at 5:05 a.m. By 8:45 a.m., cars were so contaminated with fallout that they were being washed down. After 30 minutes, officials gave up because so much radioactivity was still coming down.

At 9:25 a.m., after much of the exposure to fallout had occurred, instructions went out for people to take cover and for children to be kept in school. Within 15 minutes most of the population of St. George was under cover, and 35 minutes later the fallout had reached its peak and began subsiding, an official wrote.

Two days later, a second monitoring official arrived in St. George, and the account continues:

"We discussed the milk situation. I was unable to get [a complete list of milk producers], but I got the name of the president of the county dairymen's association. I explained that it was just as well that neither [the list nor the president himself] was available since I was afraid it would create a disturbance.

"In view of Tuesday's episode, everyone in St. George was a little concerned over any unusual incident connected with radioactive fallout and it would not take much to start wild rumors.

"For this reason it was agreed that the direct approach for the collection of milk samples would not be pursued further at this time.... That evening I purchased a quart of milk from a store in town.I located the producer and in discussing his milk supply in a general way, I learned that the milk I had purchased that evening was obtained from the St. George herd on Tuesday evening. At noon I was replaced by another [radiation] monitor [and left.]"

Soon sheep in the area began to die and developed radiation burn-like skin lesions. Lambs were born fully developed but undersize.

The AEC would later deny sheepmen's claims for damage, saying the bomb tests were not the cause. In an Octover 1953 meeting, one AEC official, Dr. Gordon Dunning, who for years would defend the safety of the test blasts in the face of mounting evidence to the contrary said any animal deaths might cause problems in "purse strings" being opened to finance weapons tests in Nevada.

A statement saying that the sheep problems were not related to fallout was then prepared for presentation to the AEC governing commissioners.