At War in the Cold War--Managing a Tactical Nuclear Weapon
This piece is different from most of the entries in You Might Want to Know. It is a version of a story shared with me by someone who during the Cold War had been the young Special Weapons Officer in a U.S. nuclear artillery battery stationed in Germany. At Dachau.
At War in the Cold War: What’s it like to manage a tactical nuclear weapon?
In 1970, he was a First Lieutenant in the United States Army and the Special Weapons Officer in an artillery battery stationed at Dachau. The battalion’s twelve howitzers were pointed east, toward the Fulda Gap. When the forces of the Soviet Union invaded western Europe, they would come through the Fulda Gap, it was thought.
The lieutenant was twenty-one. All the soldiers in his battery were younger than he was.
Their artillery pieces were eight-inch self-propelled howitzers, a very big gun. The conventional round for it contained about twenty-one pounds of high explosive. The radius of destruction for one of those conventional rounds was a hundred meters, a little more than a football field, in diameter. You wouldn’t want to be in the stands.
The Special Weapon for the battery was not a conventional round. It was the W33, a gun-type nuclear fission device. The Hiroshima bomb, Little Boy, was a gun-type nuclear fission device. Little Boy had yielded the equivalent of twelve-, maybe fifteen-thousand tons of TNT--not twenty-one, but thirty-thousand pounds of it.
Here’s a rough diagram of how Little Boy worked (from the Wikipedia entry on Little Boy. A much more detailed drawing is also now available there) and a photograph of a W33.
Significant design improvements had gone into the W33. In an underground test, the device in the W33 had yielded the equivalent of forty kilotons of TNT--3.8 million times the yield of the howitzer’s conventional round. Two and two-thirds Hiroshimas, if you want to look at it that way.
If Soviet tanks were seen to be advancing from the East, the battery was trained to fire a W33 over their heads, fused to explode about a thousand yards above them. About the altitude where Little Boy had been exploded over Hiroshima. The altitude where, it had been calculated, the destruction on the ground would be maximized.
The W33s were not usually stored already assembled. The local situation in Germany was too iffy. Protesters. Sometimes violent. The rounds would usually have to be assembled just before they were needed.
The components for the W33 were stored in a vault in a big basement that had been constructed by the Nazis under the main building of what had been the death camp at Dachau. No fewer than two soldiers were ever allowed in the vault. Both had be carrying side arms.
On the floor in the vault were “bird-cages,” steel frames with cans made of lead suspended in them. The cans contained discs of uranium. Uranium is heavier than lead. It took two soldiers to move a bird cage.
The green cans held discs of highly-enriched uranium, weapons-grade. Blue cans held inert U238. The cans were in the bird cages because a distance had to be maintained between the green cans. If those cans got too close to each other, the uranium would go critical. A chain reaction would instantly result. The uranium wouldn’t explode but the “fizzle” would kill everyone there, destroy the vault, and create a radioactive mess.
When the soldiers practiced assembling the W33, the discs of inert U238 would be used. The instructions for the day were in a thick binder called “the Bible” that was placed on a lectern under a bright light. The lieutenant’s job was to oversee the operation. The atmosphere was almost religious, he said. The first time he oversaw the process, he said, he couldn’t feel his feet.
The discs had a hole in the middle. When the round was being assembled, the discs would be slipped onto a column in the center of the round. The discs were the “projectile.” At the end of the column was a slug of uranium called a “target element” that was the size of the hole in the discs.
The yield of the round would be determined by how much U235 had been slipped onto the column.
Some of the “target elements” contained a capsule of tritium. Tritium is an isotope of hydrogen. This would “boost” the yield. Considerably.
A reflector made of beryllium would be installed around the column. When the fission started, the beryllium would reflect neutrons that otherwise would have escaped back into the fissile fuel and increase the yield.
Finally, a charge of conventional explosive would be inserted at the bottom of the round and a titanium shell secured over the assembly.
It took about two hours to assemble a nuclear round. You had to be careful, the lieutenant had learned. He had learned also that it wasn’t that hard.
The team would disassemble the round before leaving the assembly room. When they left the vault where the green cans were kept, they placed on the door a combination lock for which each of two officers had only half of the combination.
At the howitzer itself, the soldiers would practice placing dummy rounds in the tray but they never loaded a round into the breech. Once the rounds were in, the lieutenant had learned, they were almost impossible to get out.
The W33 would be fired off from the howitzer--if it came to that--with conventional explosives. When the W33 arrived over the advancing troops, the charge at the bottom of the round would detonate. This would shoot the discs of highly-enriched uranium along the column until they surrounded the target element. At the front of the shell, the arriving discs would hit some “initiators.” The initiators would release the first bursts of neutrons to start the chain reaction in the highly enriched uranium that now had been compressed to a density that was super-critical. “Super-critical” means “capable of producing a nuclear explosion.”
For the soldiers to be safe, how far from the battery would the W33 have to be when it detonated? That would depend on the yield. For the W33, the howitzer had a “throw” of five miles, possibly a little more. The area of almost total destruction at Hiroshima was about three miles in diameter. In a test, the device in the W33 had yielded more than twice what Little Boy had.
After the nuclear round had detonated over the invading troops, what were the American soldiers supposed to do? There hadn’t been any training on that. They didn’t mind. They thought they’d be dead. “We were just a trip-wire,” the lieutenant said.
Assigned to them was Quick Reaction Force, fifteen soldiers, armed with M16s and an M60 machine gun. In case they were attacked by German protesters. They were more worried about the protesters than about the Soviets. If protesters got past a first perimeter that had been established and to a second perimeter, the soldiers were authorized to shoot to kill.
Regularly, the soldiers would take discs of U238, pack them with C4, put shaped charges over each shell, link the charges with explosive “det” cord, double fuse the array and blow it up. Doing this with the discs of highly enriched uranium instead of the U238 wouldn’t cause a nuclear explosion but it would prevent anyone who managed to reach the vault, protesters or maybe Soviets, from getting the discs that would make it relatively easy for them to build a nuclear bomb. An added benefit, if the attackers prevailed, would be the large area now contaminated with radioactivity. If the attackers didn’t prevail, that wouldn’t be a benefit.
The conventional explosives they had on hand had an expiration date. When that date was reached, the explosives had to be disposed of. Using shaped charges, the soldiers would go to a range and punch deep holes in the ground. They would put the expired explosives in the holes and blow them up, and this would create a crater the size of a big swimming pool. The guys enjoyed that, the lieutenant said. Finally actually blowing up something.
In the early 1970’s, morale was terrible, the lieutenant said. Racial tensions. Fights. Muggings in the barracks. The lieutenant was afraid the soldiers weren’t combat ready.
After a year, the lieutenant, a captain now, requested and received a transfer to Vietnam.
In 1992, shortly after the end of the Cold War, the W33 was removed from service.
Most, though not all, of the many hundreds of tactical weapons we had with our forces in Europe were also removed.