Thirty miles to the north and west, Army troops were rolling through the precincts of the Nasr munitions plant. Inside, stacked in oblong wooden crates, were thousands of high-strength aluminum tubes. That equipment, and Iraq's effort to buy more of it overseas, were central to the Bush administration's charge that President Saddam Hussein had resumed long-dormant efforts to build a nuclear weapon. The lead combat units had more urgent priorities that day, but they were not alone in passing the stockpiles by. Participants in the subsequent hunt for illegal arms said months elapsed without a visit to Nasr and many other sites of activity that President Bush had called "a grave and gathering danger." According to records made available to The Washington Post and interviews with arms investigators from the United States, Britain and Australia, it did not require a comprehensive survey to find the central assertions of the Bush administration's prewar nuclear case to be insubstantial or untrue. Although Hussein did not relinquish his nuclear ambitions or technical records, investigators said, it is now clear he had no active program to build a weapon, produce its key materials or obtain the technology he needed for either. Among the closely held internal judgments of the Iraq Survey Group, overseen by David Kay as special representative of CIA Director George Tenet, are that Iraq's nuclear weapons scientists did no significant arms-related work after 1991, that facilities with suspicious new construction proved benign, and that equipment of potential use to a nuclear program remained under seal or in civilian industrial use. Most notably, investigators have judged the aluminum tubes to be "innocuous," according to Australian Brig. Gen. Stephen Meekin, who commands the Joint Captured Enemy Materiel Exploitation Center, the largest of a half-dozen units that report to Kay. That finding is pivotal, because the Bush administration built its case on the proposition that Iraq aimed to use those tubes as centrifuge rotors to enrich uranium for the core of a nuclear warhead. Administration officials interviewed for this story defended the integrity of the government's prewar intelligence and public statements. None agreed to be interviewed on the record. Vice President Dick Cheney, in a televised interview last month, referred to a National Intelligence Estimate of October 2002, which said among other things that there was "compelling evidence that Saddam is reconstituting a uranium enrichment effort." Cheney said investigators searching for confirmation of those judgments "will find in fact that they are valid." His office did not respond to questions Friday. Tubes key to nuclear debate No evidence mattered more to the nuclear debate than Iraq's attempt to buy aluminum tubes overseas. Secretary of State Colin Powell, among many others, scorned the Baghdad government's explanation that it sought the tubes as artillery rocket casings. By August, news accounts made clear that the U.S. government's top nuclear centrifuge experts dissented strongly from the claim that the tubes were meant for uranium enrichment. Meekin, whose remarks were supported by other investigators who said they feared the consequences of being quoted by name, is the first to describe the results of postwar analysis. "They were rockets," said Meekin, 48, director general of scientific and technical assessment for Australia's Defence Intelligence Organisation, speaking by satellite telephone from Baghdad. "The tubes were used for rockets." A U.S. government official, who was unwilling to be identified by name or agency, said Meekin is not qualified to make that judgment. The official did not elaborate. Kay's interim report this month said the question remains open. Participants in the Pentagon-directed special weapons teams, interviewed repeatedly since late last spring, noted that Kay's operation has taken no steps to collect the estimated 20,000 tubes in Iraq's inventory - some badly corroded, but others of higher quality than the ones the U.S. government intercepted in Jordan three years ago and described as dangerous technology. Meekin said he no longer knows the whereabouts of the tubes once stacked at Nasr. "They weren't our highest priority," he said. "The thing's innocuous." Unguarded, the tubes "could be in arms plants, scattered around, being grabbed by looters, perhaps in scrap metal yards." Scavengers, he said, most likely have "sold them as drain pipe." 'Petrochemical Three' meet with different fates The day Marines and Army mechanized troops marched past the remnants of Iraq's nuclear past, Baghdad's three most important nuclear weapons scientists met three distinct fates. Mahdi Obeidi, chief of the pre-1991 centrifuge program to enrich uranium, sat anxiously at home awaiting U.S. investigators. Jaffar Dhai Jaffar, who directed alternative enrichment efforts and other component designs under the code name Petrochemical Three, watched the U.S.-led coalition's invasion from the United Arab Emirates, to which he had decamped before fighting began. Khalid Ibrahim Said, the principal overseer of Iraq's nuclear warhead designs, drove incautiously through a newly established U.S. checkpoint. He died in a burst of gunfire from Marines. Jaffar, who remains under the protection of the UAE government, agreed to voluntary interviews with U.S. and British investigators. Those familiar with his statements said he was combative, telling the Americans - as he did during years of U.N. inspections - that there was no hidden nuclear weapons program. Iraq, he said, never resumed the effort after U.S. bombs destroyed the Tuwaitha reactors in the 1991 Persian Gulf War and the International Atomic Energy Agency dismantled enrichment and design facilities over the next five years. Centrifuge program examined It was Obeidi's former program - the use of centrifuges to enrich uranium - that the Bush administration maintained had been resurrected. Obeidi had heard the public statements, according to two close associates, and he waited with growing anxiety for arriving troops to knock at his door. Anxiety turned to puzzlement when they did not. After two weeks, the Iraqi scientist turned to an unlikely source of help: David Albright, a U.S. nuclear expert and cordial antagonist during Albright's years as a consultant to the IAEA. June 2, Obeidi led investigators to his rose garden. There they dug up a cache he had buried 12 years before and kept from U.N. inspectors: about 200 blueprints of gas centrifuge components, 180 documents describing their use and samples of a few sensitive parts. The parts amounted to far less than one complete centrifuge, and nothing like the thousands required for a cascade of the spinning devices to enrich uranium, but the material showed what nearly all outside experts believed - that Iraq had preserved its nuclear knowledge base. June 17, the CIA made public Obeidi's identity and described the rose garden cache as proof that Iraq had the secret nuclear program that the Bush administration alleged. But that, according to sources familiar with Obeidi's account in detail, is not quite what he told his interviewers. According to close associates, Obeidi expected to speak to a peer among U.S. centrifuge physicists. He was dismayed, they said, to find that his principal interrogator lacked those credentials. Obeidi confirmed the account laid out in Volume 7 of Iraq's December nuclear disclosure, which said there had been "no nuclear activity since 1991" at seven of the program's previous sites and only "medical, agricultural and industrial" activities at the others. The centrifuge program died in 1991, Obeidi said, and never resumed. He had buried the documents to prepare for resumption orders that never came. He had nothing to do with the aluminum tubes, he said, and a centrifuge program would have no use for them. Obeidi's account corresponded closely with the history laid out in Volume 3 of Iraq's official history, which covered enrichment. The physics of a centrifuge would not permit a simple substitution of aluminum tubes for the maraging steel and carbon fiber designs used by Obeidi. The tubes in Obeidi's design were also specified at 145mm in diameter; the aluminum tubes measured 81mm. Investigators going home Meekin, the Australian general who had principal responsibility for collecting Iraqi military technology, said his 500-strong unit is disbanding, its work largely done. According to U.S. government officials, some of Kay's leading nuclear investigators have already departed Iraq. Nuclear physicist William Domke, who ran the centrifuge investigation, returned last month to his intelligence post at the Energy Department's Lawrence Livermore National Laboratory. Jeffrey Bedell, Domke's counterpart at the Los Alamos National Laboratory, also has come home. Domke and Bedell, according to people who know their work, confirmed their prewar analysis that the tubes were not suited for centrifuges and that Iraq had no program to use them as such. The investigation to date, Meekin said, suggests that Iraqi efforts to obtain dangerous technology since 1991 met with modest success at best. "By and large our judgment is that sanctions have been pretty good, or the sanctions effort, to prevent the import of components," he said. In the realm of nuclear proliferation, he said, "I guess there's more fertile ground in North Korea or Iran." P.I.N//The Macon Telegraph.com