Forty years ago this week, a Soviet warplane bombed this area with an atomic weapon more powerful than the one that flattened Hiroshima.

Nikolai Levonov, who had been evacuated from his farming village a few miles from the center of the target zone, returned the next day to find his house flattened and his tomatoes turned from green to red. Levonov, now 68, set about rebuilding his house. He also ate the tomatoes.

The nuclear explosion of Sept. 14, 1954, was intended to test whether soldiers could fight in conditions of nuclear war, Russian army Col. Alexander Vasiakin, 39, explained during a recent tour of the site. About 44,000 Soviet troops were deployed in 140 miles of trenches that had been dug for the test. Within minutes of the 9:33 a.m. explosion, they were ordered into the atomic inferno.

After the test, Vasiakin recounted, the soldiers were encouraged to wash off, but there was not enough water to go around. They were also encouraged to destroy their clothing, but many refused to give up the leather belts they had been given for the occasion. Many may have died as a result, Vasiakin said.

The Soviet leadership -- including Marshal Georgy Zhukov, who watched from an observation tower three miles to the south, with defense ministers from China, Poland and Yugoslavia -- concluded that soldiers could, in fact, fight through a nuclear battle.

"They had a list of 100 cities which the Americans were preparing to hit with three bombs each, including {nearby} Orenburg and Sverdlovsk," Vasiakin said. "Naturally, we were preparing for this."

Early in the atomic era and at the height of the Cold War, both the United States and the Soviet Union put servicemen and civilians in nuclear harm's way, and both governments were reluctant to acknowledge the consequences or compensate the victims afterward. Here in Russia, totalitarian secrecy and people's fear of speaking out kept the Totsk test entirely hidden until just a few years ago.

Last week, Defense Minister Pavel Grachev, visiting the Totsk testing range to inspect the first U.S.-Russian joint exercises here, condemned the atomic test as "barbaric" and "monstrous." But even with that change in official line, one 74-year-old survivor, who has suffered from skin cancer and other diseases she attributes to the blast, refused to give her name.

"I had to swear an oath that I would never discuss it, for the rest of my life," the woman said.

Because the Soviets apparently conducted no comprehensive medical studies, it is impossible to say how many soldiers and civilians lost their lives because of exposure to radioactivity. Orenburg region officials recently reported that the incidence of tumors and congenital disorders increased five-fold in the past 40 years. They attributed the problems not only to the nuclear test, but to chemical-weapons testing that polluted the groundwater in the 1920s and 1930s and to other contaminants as well.

What is clear, from interviews with survivors still in the area, is that civilians were protected only haphazardly and soldiers not at all. Some people were evacuated, others were not. Some said they were advised to leave but did not bother. Others said they left even though they were told they could safely stay as long as they lay on the ground and did not look up.

Lyubov Ivanova, 70, said that before being evacuated she lived near the center of the target area, in a village that was wiped out and has never been rebuilt. But "like idiots," she said, she and her neighbors returned two days later to see what had happened to their houses, and when grass began growing again from the scorched earth they drove their animals there to graze.

"No one told us not to," Ivanova said. "And after all, we have to live... . We didn't know the danger, and they didn't tell us anything."

"Now," she said, "my son and daughter are both sick, and many of my friends have died."

On the day of the test, soldiers brought goats, cows, camels and other livestock to the target center, along with all kinds of military equipment and radiation instruments. Airmen in a Tu-4 -- a Soviet bomber modeled on the American B-29, one of which dropped the bomb on Hiroshima -- launched the device from about six miles up.

The bomb exploded at an altitude of about 380 yards, forming a huge mushroom cloud. It detonated with a force equivalent to 20,000 tons of TNT, compared to perhaps 15,000 for the Hiroshima bomb. Villagers miles away reported a deafening explosion, followed by fires and violent shock waves rumpling the earth, shattering windows and collapsing houses. The 74-year-old woman who would not give her name said blood ran from her ear after the explosion as she hid from it in the military garrison about four miles away.

In accordance with the plans for the military exercise, 20 minutes after the detonation, scores of warplanes were sent toward the center of the target area to bomb whatever "enemy" might have survived. As the mushroom cloud drifted east, about 170 pilots found themselves flying through it.

Within another 20 minutes, the infantry was sent out of the trenches and toward the center. Many soldiers received a "second shock," Vasiakin said, when they saw what had happened to the animals near the explosion.

"We already had many manuals written on the tactical use of nuclear weapons, but we wanted to see what would happen in real life -- the morale and psychological response of the soldiers, and so forth," the colonel said. "We knew already this would be the only such test, and we wanted to make it a high-quality experience."

Today, a small monument stands near the target center, honoring the soldiers who "defied danger and fulfilled their military duty in the name of the defensive might of our homeland." In the meadow all around lie the battered remnants of tanks and aircraft, vestiges of the bombing range this became in the 1980s.

Background levels of radiation remain slightly higher here than in surrounding territory, Vasiakin said, and the trees have never grown back.