This one is for the geeks. Last week I reported on an article in the latest issue of Physics Today magazine, written by a former senior defense official in close collaboration with a former director of technical intelligence at the Los Alamos National Laboratory, reporting that China gave Pakistan the blueprints of the first atomic bomb China had tested in 1966 and helped Pakistan test its own first atomic bomb at the Chinese nuclear test site on May 26, 1990â¿¿eight years before Pakistan openly â¿¿went nuclear.â¿¿ The article also contained a number of other startling assertions, including the claim that China operated a so-called fast-burst reactor to test bomb radiation effects.
Today, over lunch at the Union Club in New York City, the author of the article, Thomas C. Reed, stood by those allegations and filled in background. Reed, a nuclear physicist who started his career at the Lawrence Livermore National Laboratory in the 1950s, served as Secretary of the Air Force in the mid-1970s, straddling the Ford and Carter administrations. He also held a number of other high-level national security positions in the Nixon, Reagan, and George H.W. Bush administrations. He was closely allied politically and personally with Reagan.
Reed confirmed that China provided Pakistan bomb information starting in 1982, having itself obtained valuable assistance from the atomic spy Klaus Fuchs during the 1950s, that it let Pakistan do its first test at Lop Nur in 1990, and that it also let France do hydro-nuclear experiments at its test site during the 1990s.
In a hydronuclear test, a bomb containing less than a critical mass of fissile material is detonated, to evaluate the performance of non-nuclear components. Reed says that France conducted such tests in Algeria in the 1950s, in the open, as did the Soviet Union in Kazakhstan; more responsibly, the United States and China did hydronuclear tests in steel containers, to prevent dispersal of radioactive material.
According to Reedâ¿¿s article, Danny Stillman of Los Alamos initially got the attention of the Chinese when he asked them whether they had a fast burst reactor, which they did. The question clearly implied that the United States had such a reactor, which I had not known, even though Iâ¿¿ve covered nuclear matters for thirty-plus years. I was not even aware that reactors had been designed deliberately to simulate the impact of nuclear explosions on nuclear weapons (although seventeen years ago I published an article in MITâ¿¿s Technology Review reporting an expert consensus that the basic cause of the Chernobyl catastrophe was a superprompt criticalityâ¿¿in plain English, a nuclear explosion).
How could a reactor be designed to go superprompt critical without actually exploding like a bomb? After all, as the great physicist Hans Bethe observed after Chernobyl, once a reactor goes superprompt critical, no control rod system can react fast enough to prevent an explosion.
Stillman says the general idea was to build a reactor with medium-enriched uranium (say 20 percent), with a void in the middle in which a nuclear weapon could be placed, and a configuration that enabled controllers to literally disassemble the reactor by having parts of it drop down. That way, a runaway criticality could be brought under control--not merely by removing control rods, which would not by itself sufficeâ¿¿but by actually inducing the reactor to fall apart. Even so, when a nuclear weapon was placed in the void and the reactor started to go supercritical, a â¿¿pre-scramâ¿¿ would be initiated, so that at just that point control rods already would be dropping and the reactor would be already disassembling. The experiments were very hazardous and had to be timed at a scale of tens of microseconds.
During the 1960s, Stillman says the United States built three such reactors, Kukla, Fran and Super-Kukla, named after a television series (they never got to Ollie). The point of this? To study how an intense radiation burst from enemy weapons would affect the U.S. nuclear weapons stockpile. In other words, these tests were conducted in the context of nuclear and missile defense efforts.