Hypothetically, deep, fresh water should be able to insulate the populated area around them from radiation if the bomb went off. Unfortunately, the weapon’s shockwave was still going to be lethal.
Chapter Ten
Sam sat on the edge of the east river bank panting raggedly.
A black helicopter hovered directly above where the sub had sunk in the Potomac. Its side doors swung open. Seven Navy SEAL divers stepped off the skids, dropping into the river, disappearing into the water below.
Sam watched as all but one of the elite team of Navy divers sank into the now murky water, while one of the men surface swam over to meet him.
The Navy diver came out of the water grinning. “My name’s Lieutenant Worly. I’m here to make sure you’re all right! Your crazy escapade to stop the submarine from continuing up the Potomac? It was genius! We spotted the sub inactive on the bottom of the river.”
Sam’s cheeks dimpled with amusement. “Hey, it worked, didn’t it?”
Worly’s smile disappeared. “We’ll soon find out.”
“Yeah, we will.” Sam offered his right hand. “I’m Sam Reilly by the way.”
Worly shook his hand with a firm shake, meeting his eyes. “It’s a pleasure to meet you, Sam Reilly. No injuries?”
“None. Thanks, I’m fine.”
“I’ve heard a lot about you.”
“All good, I hope.”
The diver shook his head and released Sam’s hand. “Not all good.”
Sam shrugged, indifferently. He’d been called names before. “What do you think? Will you be able to defuse it?”
“A nuclear bomb from the 1940s?” The diver cocked an eyebrow. “Hopefully. We won’t know for sure until we open up that mini-sub and find out what type of arming plugs they were using.”
“You don’t know?” Sam asked, still catching his breath from his dive.
“No one knows. How could we? Until a few hours ago, no one had even heard of Germany successfully producing a nuclear weapon during WWII.” The diver sighed. “We’re hoping the arming plugs were based on similar technology to what the Manhattan Project developed during that period — but that’s only a hope. In reality, there’s every chance that the Germans came up with a different solution to simultaneous detonation.”
Sam asked, “I was worried there was a risk of it being accidentally triggered by the sudden change in the sub’s depth when I sank it. Apparently not.”
The SEAL shook his head. “Where traditional bombs can be activated by any sudden change in movement, nuclear weapons take an extraordinary amount of effort to activate.”
“A nearby explosion won’t set off the reaction?” Sam asked.
“Not a chance. Do you know how a nuclear explosion works?”
Sam shook his head. “Not a clue. I must have been away from class the day they were teaching that in school.”
The diver gave him a thin-lipped smile. “Basically. They work by simultaneously compressing the fissionable material — either enriched uranium 238 or plutonium 239 — to its critical mass.”
“The weapon works on an implosion?”
“Exactly. Later they developed what is called a neutron trigger — also known as a modulated neutron initiator — capable of producing a burst of neutrons on activation that would kick start the chain reaction of nuclear fission.”
“But not in 1945?”
“No.” The diver said, “I can’t say for certain what the Germans had developed, but at Oak Ridge, the Manhattan Project built an exploding-bridgewire — EBW — a precision-timed detonator. It’s used to initiate the explosion using an electric current, similar to a blasting cap, that precisely compresses the bomb's plutonium pit and initiates the reaction.”
“How did they do that?”
“EBW detonators were typically constructed of either gold, platinum, or an alloy of the two, and are activated with the application of a strong electrical current — about 1000 amperes per microsecond — typically from a Marx generator. This powerful current heats the metal so quickly and in such a small area that the liquid vaporizes. A few nanoseconds after, the wire explodes, creating a shock wave and releasing the contained thermal energy, igniting the rest of the reaction.”
“Interesting.” Sam glanced at his watch. Nearly five minutes had passed since the rest of the SEAL team had disappeared beneath the surface of the Potomac. “As I’m fit and healthy, why are you still here?”
“I’m making sure you don’t dive in for curiosity’s sake.” Then Worly gave a rueful smile. “Also, my wife just gave birth to a baby girl. That might have been the reason I got picked to keep you out of trouble.”
“Congratulations,” Sam said, bestowing a genuine smile. “Your first?”
“Yes, and it makes me doubly worry.”
Sam frowned. He didn’t know a lot about nuclear weapons, but he knew enough to realize they were well within the blast radius. “I don’t expect that the bank of the Potomac is far enough away to keep either of us out of trouble…”
The diver shrugged philosophically. “Then my men will need to make sure the bomb doesn’t get the chance to detonate.”
They waited. With every minute that passed, Sam’s jaw clinched harder.
Finally, a head broke the surface of the river, swimming over to the two of them. “Worly,” the other man called. “We need your help down here, and we could use yours, too, Mr. Reilly. The mini-sub needs to be moved so we can get into it, we don’t have enough manpower to do it on our own. We could either wait for a truck with a winch to get out here —”
“Or I could free-dive down with you and we can see if with more manpower we can push it ourselves,” Sam said. “All right, let’s do this.”
Worly said, “You can buddy breathe from my regulator.”
“Thanks.”
Sam buddy-dived to the bottom with Worly.
The Potomac had silted up from the crash at the bottom as the current was a steady push from upstream. Sam free-dove downward. The midget sub was a dark shadow on the riverbed, he could almost have mistaken it for a rock.
The entrance to the sub was a hatch in the front of the finlike conn tower, and it was butted up against a solid piece of rock. Worly offered Sam his regulator, and he took a few breaths as he considered the situation. The divers were trying to roll the submarine off the rock. Rotating it would likely work better.
Sam swam to the aft end of the midget sub and started pulling the chain away from the propeller. He had no intention of unjamming it, only shifting the weight a little. He dropped the chain down into the silt at the bottom of the riverbed, then waved the other men over.
After a short, waved conference, the four men braced themselves and pulled on the chain. The conn tower caught against the rock, and as the aft end of the midget sub swung one way, the forward end swung the other. A few seconds later, the hatch was clear of the rock, with just enough room for a diver to maneuver.
Sam and Worly watched as the other divers prepared to enter.
The hatch was soon opened, and a pair of the divers slipped inside. For a couple of minutes, Sam had almost forgotten that their lives were at stake.
Now he remembered.
Soon one of the divers had emerged. He swam over to the two of them and waved them toward the hatch. Sam took another breath from the regulator, then swam inside.
The sub was cramped, but empty. No pilot.
No nuclear bomb.
The first diver waved toward Sam, then pointed to one of the inner walls. On it, written in diver’s chalk, were the words:
Mr. Sam Reilly,
So good of you to join us. Now that you’re here, the game can begin…