N. Korean Evidence Called Uncertain
By Glenn Kessler
Washington Post
January 22, 2004

Scientist Describes Show and Tell at Nuclear Plant Tour

The North Korean engineers put a red metal box on the table and opened it. They pulled out a white box made of wood that fit snugly in it. They slid off the top and pulled out two clear jars, which looked as if they had once held marmalade. The lids were sealed tight with tape.

Siegfried S. Hecker, a former director of Los Alamos National Laboratory, peered at the jars from several feet away. One contained a greenish powder, the other an oddly shaped piece of metal. It looked a bit like a funnel, 11/2 inches high and an eighth of an inch thick.

Hecker focused on the metal. This, the North Koreans proudly proclaimed, was their "deterrent" -- plutonium that had been recently created and shaped from the waste of nuclear fuel rods that until a year ago had been under the careful watch of United Nations inspectors.

The jars and boxes were whisked away. Wait a minute, Hecker said. "It looks like plutonium, but there is no way I can be sure it is plutonium," he said. "I want to hold the jar." The red box reappeared.

North Korea's willingness to show off its Yongbyon nuclear facility -- and eagerness to show it can produce plutonium -- was intended to demonstrate Pyongyang is serious about breaking the stalemate with Washington over its nuclear programs, members of an unofficial U.S. delegation say. But the delegation's observations have alarmed U.S. officials because the trip two weeks ago appears to confirm that North Korea has processed all 8,000 spent fuel rods -- giving them enough weapons-grade plutonium for as many as half a dozen nuclear weapons.

U.S. intelligence had been divided on this question, with the State Department's intelligence arm in particular arguing it was unclear whether the rods had been reprocessed.

Hecker, in a two-hour interview and in testimony yesterday before the Senate Foreign Relations Committee, said he cannot say conclusively that the metal displayed was recently reprocessed plutonium, in part because he did not have the necessary equipment. Moreover, the North Koreans did not provide evidence to the visitors the plutonium had been placed in a nuclear device. But the delegation also saw a small reactor operating, apparently smoothly, producing enough plutonium for an additional bomb a year.

At one point, Hecker said, Vice Foreign Minister Kim Gye Gwan noted that Libya and Iraq were proved not to have nuclear weapons. Then he bragged to his visitors, "But we have weapons of mass destruction."

The following account is based on the interview with Hecker and supplemented by interviews with other delegation members

The delegation was led by Stanford University scholar John W. Lewis, and its members were the first Westerners to visit the Yongbyon Nuclear Scientific Research Center since U.N. inspectors were ousted more than a year ago. The group arrived Jan. 8 at 1030 a.m., after a two-hour drive, sometimes over an unpaved road, from Pyongyang.

It spent nearly eight hours there, viewing the small 5-megawatt reactor, the cooling pond that once held the rods and the facility for reprocessing. They also drove past the crumbling facade of a much larger, 50-megawatt reactor, where construction had been halted 10 years ago under an agreement with the Clinton administration.

After an introductory meeting at a guest house, the group toured the small reactor. It saw a steam plume emanating from the cooling tower in the morning and the afternoon, and all indications from the control room suggested the reactor was operating smoothly.

The North Koreans said the reactor began operating last February to provide heat for the nearby town, replacing shipments of fuel oil that had been suspended by the Bush administration in late 2002 when the nuclear crisis began. Hecker, a metallurgist with top-secret clearances, noted to his hosts that the uranium fuel rods in the core of the reactor were also generating up to six kilograms of plutonium a year.

The delegation then visited the cooling pond for spent fuel, next to the reactor. At great expense, the United States had provided 400 stainless-steel canisters to store the 8,000 rods in a deep pool of water -- and the canisters had been sealed to prevent tampering.

The group dressed in protective gear -- smocks, booties and skullcaps -- and looked into the pool. The seals and locking plates were gone. There was a thin layer of ice on the pool. A number of canisters were open.

"Okay," one of their North Korean hosts said. "You have that answer."

"Wait a minute," Hecker objected. "There were a whole bunch of canisters that were closed, so I can't go back home and say they are all gone."

The North Koreans suggested he select one at random and they would open it up. Hecker picked one that was seven rows down and four over, and then four men operated a crane to bring it up and unscrew the top. It should have held 20 rods. Using a light, Hecker confirmed it was empty.

Finally, the delegation was taken to the reprocessing facility, where the plutonium that has built up in the rods is separated. The delegation peeked through the heavily shielded windows where the separation is done, but no one was at work. The North Koreans said they had completed reprocessing the rods at the end of June.

"Okay," one North Korean official said. "We have demonstrated our deterrent."

Hecker again objected, saying that he had seen nothing to prove processing had taken place and that the rods could be anywhere. That's when the North Korean brought out the red box with the two jars. One jar held what appeared to be plutonium oxalate powder -- which could be turned into plutonium. The other jar held the metal piece.

"This is a scrap piece from a casting from our recent campaign," one official said.

"What's the density?" Hecker asked.

"Between 15 and 16."

Hecker raised his eyebrows, since plutonium has a normal density of about 19.8 grams per square centimeter. This meant the North Koreans had produced an alloy, making the notoriously brittle metal easier to manipulate.

When Hecker asked what element was added to the plutonium, the North Korean shot back "I'm not authorized to tell you that, but you know. It's the same thing you use."

Hecker, using plastic gloves, wanted to hold the jar to conduct two simple tests -- to see how heavy it was and whether it was warm. Plutonium is twice as dense as iron and is slightly warm to the touch because of its radioactivity. Hecker said it felt heavy and, in the frigid air of the facility, the jar wasn't cold. But it also wasn't hot. When Hecker noted to a North Korean official that it wasn't very warm, he replied, "That's because the '240' content is low."

This also was potentially important. Plutonium-240 is one of the two main isotopes, or chemical types, of plutonium used in weapons. Plutonium-240 is more radioactive than the other isotope, plutonium-239, and it accounts for most of the heat given off by the metal. Reactor plutonium has as much as 40 percent plutonium-240; weapons-grade plutonium, by contrast, has less than 6 percent of plutonium-240.

When Hecker asked to have his hands checked for radiation, the North Koreans brought in a Geiger counter. The red box was still in the room, and it set off the device when it was turned on. "This stuff was radioactive," Hecker said.

The day after the Yongbyon visit, a senior North Korean official, Li Gun, approached Hecker and declared, "We've shown our deterrence."

Hecker was blunt. "No, you didn't show us your deterrence," he said. A nuclear deterrent, he told Li, has three elements weapons-grade plutonium, a nuclear device and a delivery system for the weapon.

"Let me make sure we understand each other," Hecker said. "You showed me nothing -- no facilities. You had me talk to no people that give me any indication as to whether you have the ability to go from plutonium metal to a nuclear device. I saw nothing."

"Well, you saw the capability of our people," Li replied. "Didn't that convince you that we know how to build a nuclear device?"

Hecker said what he saw required reactive physics and chemical engineering. The next steps take more physics and metallurgy, knowledge of high explosives and testing, and much more.

"Look, this is just like somebody in an automobile company telling me that just because they've got steel, they know how to build an automobile," Hecker told Li. "It's the same thing."

A disappointed Li said he would try to find someone to speak to Hecker who could prove North Korea has that ability. But in the evening Li came back and said they had run out of time.

Staff writer Joby Warrick contributed to this report.