ABU GHRAIB, Iraq -- U.N. inspectors, wearing baby-blue baseball caps and armbands, were roaming through a missile factory the other day when they came across a room with a couple of ominous warning signs posted outside: "Caution," the signs said. "Risk of Ionizing Radiation."

What´s in there? the inspectors asked.

Just an X-ray machine, the plant director answered.

Show us, they said.

So, as the plant director recalled, he escorted the team into the room and put some metal into the machine. Out came the film familiar to anyone who has been X-rayed, he said.

In the three weeks they have been scouring Iraq for evidence of weapons of mass destruction, U.N. arms experts have been poking and prodding everywhere they can, testing seemingly innocent explanations, rifling through files, taking soil and water samples, measuring the air for radiation. At a distillery suspected of developing biological weapons, they smelled the alcohol. At a missile factory, they had a rocket test-fired to make sure it did not exceed range restrictions.

The inspectors in Iraq, whose ranks increased over the weekend to 105, have accelerated their schedule to full speed and now fan out early each morning to facilities throughout the Baghdad area and beyond, from a cement factory to a pesticide store, from the most secretive of military bases to government research centers. They visited 13 sites yesterday, their busiest day yet, as they worked to collect and collate information to report to the U.N. Security Council on the status of Iraq´s banned weapons programs.

So far, the inspectors have disclosed few findings and drawn no conclusions. That is the work of higher-ups at U.N. headquarters in New York, where diplomats are keenly aware that the outcome of the searches could bring a decision by the Bush administration on whether to wage war on Iraq.

"It will take us some time to come up with a bigger picture," said Hiro Ueki, Baghdad spokesman for the U.N. Monitoring, Verification and Inspection Commission, or UNMOVIC.

But as they settle into a routine, the inspectors have begun focusing more attention on a handful of the most critical facilities. Nuclear experts from the International Atomic Energy Agency, for instance, have learned the route to the town of Tuwaitha all too well. About 15 miles southeast of Baghdad, it is home to the Tuwaitha Nuclear Research Center, the heart of Iraq´s nuclear program.

Iraq has said it halted its nuclear weapons development program a decade ago. Inspectors have combed through the sprawling Tuwaitha facility six times so far to inventory nuclear materials, most recently on Sunday when they took samples of water and silt.

Inspectors have also spent considerable time at the Qaqaa complex not far from Tuwaitha, where they have searched for indications of nuclear or chemical weapons. They first showed up there on Nov. 30 to remove an air sampler, and then returned five more times, including yesterday, to examine an explosives production plant and a sulfuric acid plant.

More and more, inspectors are choosing to return to facilities they had already inspected. Most of the inspections yesterday, for example, were repeat visits.

However, since making a visit to a presidential palace to test their ability to get in, they have not gone to any of the dozens of others, sticking at least for now to more conventional and less provocative locations.

To avoid becoming too predictable, however, the inspectors have tried to maintain the advantage of surprise. Over the weekend, for instance, nuclear specialists showed up after dark at the Muahaweel military base south of Baghdad.

So far, they have encountered none of the intransigence that marked their predecessors´ experience in Iraq during the 1990s, which led to their withdrawal in 1998 and a subsequent four-day U.S.-British bombing campaign. Iraqi officials have kept to their word in opening the gates when the U.N. teams arrive. The one time a lone duty officer did not have a key, the inspectors sealed rooms and returned the next day to find no sign of tampering.

Recognizing that demonstrating openness may be the best way to undercut international support for war, Iraqi officials urge foreign journalists to cover the inspections each day instead of turning to another subject.

"The weapons inspections carried out so far have uncovered the lies of Britain and the United States, and Iraq will continue cooperation with the U.N. Monitoring, Verification and Inspection Commission to ensure the success of its mission," Gen. Hossam Mohammed Amin, head of the National Monitoring Directorate, the Iraqi liaison to the United Nations, told the official Al-Iraq newspaper last week.

To test that further, the chief U.N. weapons inspector, Hans Blix, has asked Iraq to produce a list of scientists associated with its weapons programs by the end of the year, possibly so they can be interviewed outside the country. During an interview on Lebanese television yesterday, Amin reiterated that Iraq would comply.

The inspection process has taken the U.N. experts far and wide. Not long ago, they showed up at the gate of the Al Abraj distillery, which produces about 100 cases of gin, whiskey and arrack a day. About six inspectors toured the factory, 12 miles south of Baghdad, checking out the bottling conveyor belts and the steam cleaners and the storerooms filled with labels, cardboard cartons and jugs of fruit flavors.

Alber Poulus Younan, the plant director, pulled a rubber hose from the machines, let a liquid that was 96 percent alcohol spill over his hand and held it up for the inspectors to smell, as he did again yesterday for a couple of visiting journalists. Whatever else it might be, a look around left no doubt that the Christian-owned Al Abraj produces many bottles of booze.

"It´s a factory for drink," Younan said. "They´re looking for something special. I don´t know what it is."

The answer came in what the inspectors showed most interest in -- the fermenters. Five giant, rusting 40-cubic-yard vats sat in a building with labels that were attached to the vats by other inspectors four years ago. The new inspectors checked the bar codes against their records and moved on.

Fermenters can be critical to the weaponization of such biological pathogens as anthrax. But Younan and the distillery´s owner, Shakir Easa, laughed at the notion that their machines produce killer spores. "It´s funny, because any simple citizen of the world comes to this place and he can tell it´s just an alcohol factory," Easa said.

Another team of inspectors spent nearly three hours last weekend at a missile factory in Abu Ghraib, 25 miles west of Baghdad. The plant director, Hussein Mohammed, told the inspectors that he produces only al-Samoud liquid-propellant rockets that travel less than the 93-mile limit imposed by U.N. sanctions, contrary to assertions by the U.S. government.

With the sound of clanging metal and the odor of industrial cleaning fluid in the air, men in white smocks and women in head scarves stared at the inspectors as they examined the 18 buildings surrounded by a fence topped with concertina wire. Hanging above them in the courtyard was a massive tile portrait of President Saddam Hussein.

Mohammed said he had no warning the inspectors were coming. "Even as they were arriving, I learned they were here," he said. But neither, he added, did he have anything to hide. "We want the inspectors to show that we´re not making any such weapons and we hope that the Security Council will take a decision to lift the blockade against the Iraqi people," he said. (© 2002 The Washington Post Company 12/17/02)