By Walter Pincus
Washington Post Staff Writer
Monday, October 18, 2010; 10:33 PM
Outside of the nuclear weapons communities, little notice was paid last week to the announcement that authorization had finally come through to begin dismantling the last of the minivan-size B-53s, the most powerful thermonuclear bombs ever deployed in the active U.S. stockpile.
A terror weapon if there ever was one, the 10,000-pound B-53 was designed to deliver an explosion of nine megatons. That is the equivalent of 9 million pounds of TNT, or 600 times the power of the bomb that destroyed Hiroshima.
Believe it or not, the last 50 B-53s were not retired from the active stockpile until 1997, and even then some were held as a "hedge" in case a new threat emerged.
The two nuclear bombs that destroyed Hiroshima and Nagasaki, termed military targets at the time, immediately killed more than 200,000 people and resulted in the deaths within five years of an additional 100,000. They won the war against Japan and none has been used since.
Why did the United States in the late 1950s and early 1960s need to build more than 300 B-53s? And why were as many as 50 kept through the late 1990s, while the U.S government built and deployed thousands of other nuclear weapons with less powerful warheads?
What did war planners have in mind? It's a tale that should have lessons for today as the Obama administration considers spending more than $180 billion over the next decade modernizing the nation's nuclear stockpile and replacing the intercontinental ballistic missiles, strategic submarines and aircraft that would deliver them.
There are steps being taken to win Republican votes for a treaty with Russia designed to reduce nuclear weapons. The lesson: Don't build more weapons than you need or could use.
From the start, the first B-53s built in 1962 were thought of as bunker busters, needed to attack deep underground shelters near Moscow that U.S. intelligence said were built to protect the Soviet leadership. The bomb had a rear compartment that contained five parachutes; they were designed to lay the bomb down softly on the surface so that its explosive power would send a shock wave through the earth to collapse the underground shelters, crushing the people within them. When production was halted in mid-1965, more than 300 B-53s had been built.
The test of the first U.S. thermonuclear fusion device took place in 1952 as a surface shot on Enewetak Atoll in the South Pacific. Called Ivy Mike, the bomb, like the B-53, had a yield of nine to 10 megatons.
Its radioactive fallout on Marshall Islanders living on Rongelap Atoll 140 miles away caused any number of health issues. They included miscarriages and thyroid losses among teenagers who played in the coral flakes that fell like snow on the beaches. The test shot even delivered low-level radiation to an atoll more than 300 miles away.
Imagine for a moment the impact radioactivity would have had on the world if several B-53s had been dropped on the Soviet Union. The Strategic Air Command (SAC) had models of what the fallout could have been though they never have been made public. Inside SAC, during the Cold War years the B-53 was known as "a crowd pleaser," a former senior officer told me recently.
Some early versions of the B-53 were retired as early as 1967. In the 1970s, the United States was dismantling 1,000 to 3,000 nuclear weapons a year, using their fissionable material to build thousands more modern and safer ones.
Through the 1970s, 50 B-53 bombs and 54 Titan liquid-fueled ICBMs, with identical nine-megaton warheads, had the high-priority responsibility to destroy the Soviet underground bunkers. But in September 1980, after a Titan exploded accidentally in Arkansas, the decision was made to retire the remaining deployed Titans. That left the B-53s alone with the task, causing Pentagon planners to begin developing a new nuclear bunker buster.
By 1987, there were 25 of the B-53 bombs in the active stockpile. They were considered so dangerous that only dummies were used when crews practiced loading and unloading them on B-52s.
In the spring of 1987, with development of a replacement bomb delayed, the Reagan Pentagon decided to activate 25 more B-53s, so that 50 would be available if needed. It was not until 1997, when the bunker-busting B-61-11s were deployed, that retirement of B-53s began- but not disassembly.
Disassembly of nuclear weapons is a costly and dangerous process. Safety studies and special tools are needed just to handle the chemical explosive elements of the bomb, according to a 1994 Department of Energy report. "This study does not include study of disassembly of the B-53 primary [its nuclear package] since tooling and procedures are still being developed for this process," the study said.
More recently, the National Nuclear Security Administration (NNSA), which runs the nation's nuclear weapons complex, completed safety studies that will permit its Pantex Plant near Amarillo, Tex., to begin dismantling the B-53s.
The process includes separating the high explosives from the nuclear material. The second stage calls for the nuclear materials and other components to be shipped to NNSA's Y-12 plant at Oak Ridge, Tenn., where a building has been upgraded to handle the job. There the enriched uranium components will be removed and stored. Then other nonnuclear components will be sent to other NNSA plants for final disposition.
The current dismantlement program for retired U.S. nuclear weapons has a completion date of 2022 because thousands of them await dismantlement. One cause of the bottleneck is that the Pantex plant is the only NNSA facility that can assemble and dismantle nuclear weapons. More than half of Pantax's tasks involve putting together warheads in the life-extension program so that they can be among the more than 1,000 the United States can keep deployed over the next 20 years.