Tuesday, 8 September 2015

How Safe are Nuclear Weapons ?

Obviously when used as a weapon, a nuclear bomb is just about the most deadly piece of military equipment devised. It is a weapon with the capability of destroying all human life on the planet when used as part of a mass attack. This piece concentrates on the handling, movement and storage of nuclear weapons. From their creation and first use in 1945 there have been innumerable incidents where a catastrophic accident has been avoided as much by luck as by intention.

In Eric Schlosser’s history of nuclear weapons ‘Command and Control,’ he details some of the worst incidents. Although the following happened in the 60’s, it is still very scary. 
“On January 23, 1961, a B-52 bomber took off from Seymour Johnson Air Force Base in Goldsboro, North Carolina, for an airborne alert. The flight plan was a long, circular route along the East Coast. At the end of the first loop, the B-52 met its tanker and refuelled. At the end of the second loop, after more than ten hours in the air, the bomber refuelled again. It was almost midnight. Amid the darkness, the boom operator of the tanker noticed fuel leaking from the B-52’s right wing. Spray from the leak soon formed a wide plume, and within two minutes about forty thousand gallons of jet fuel had poured from the wing. The command post told the pilot to dump the rest of the fuel in the ocean and prepare for an emergency landing. But fuel wouldn’t drain from the tank inside the left wing, creating a weight imbalance. At half past midnight, with the flaps down and the landing gear extended, the B-52 went into an uncontrolled spin. …..the crew were ordered to bail out. 

The B-52 was carrying two Mark 39 hydrogen bombs, each with a yield of 4 megatons. As the aircraft spun downward, centrifugal forces in the cockpit pulled a lanyard in the cockpit. The lanyard was attached to the bomb release mechanism. When the lanyard was pulled, the locking pins were removed from one of the bombs. The Mark 39 fell from the plane. The arming wires were yanked out, and the bomb responded as though it had been deliberately released by the crew above a target. The pulse generator activated the low-voltage thermal batteries. The drogue parachute opened, and then the main chute. The barometric switches closed. The timer ran out, activating the high-voltage thermal batteries. The bomb hit the ground, and the piezoelectric crystals inside the nose crushed. They sent a firing signal. But the weapon didn’t detonate.

Every safety mechanism had failed, except one: the ready/safe switch in the cockpit. The switch was in the SAFE position when the bomb dropped. Had the switch been set to GROUND or AIR, the X-unit would’ve charged, the detonators would’ve triggered and a thermonuclear weapon would have exploded in a field near Faro, North Carolina. 
The other Mark 39 plummeted straight down and landed in a meadow…near the Nahunta Swamp. The high explosives did not detonate, and the primary was largely undamaged. But the dense uranium secondary of the bomb penetrated more than seventy feet into the soggy ground. A recovery team never found it, despite weeks of digging. 
The Air Force assured the public that the two weapons had been unarmed and that there was never any risk of a nuclear explosion. Those statements were misleading. The T-249 control box and ready/safe switch, installed in every B-52 bomber had already raised concerns at Sandia1. The switch required a low-voltage signal of brief duration to operate — and that kind of signal could easily be provided by a stray wire or a short circuit, as a B-52 full of electronic equipment disintegrated midair.

A year after the North Carolina accident, a SAC2  ground crew removed four Mark 28 bombs from a B-47 bomber and noticed that all of the weapons were armed. But the seal on the ready/safe switch in the cockpit was intact, and the knob hadn’t been turned to GROUND or AIR. The bombs had not been armed by the crew. A seven month investigation by Sandia found that a tiny metal nut had come off a screw inside the plane and lodged against an unused radar-heating circuit. The nut had created a new electrical pathway, allowing current to reach an arming line — and bypass the ready/safe switch. A similar glitch on the B-52 which crashed near Goldsboro would have caused a four megaton thermonuclear explosion. ‘One simple, dynamo-technology, low-voltage switch stood between the United States and a major catastrophe.’
The groundburst of that 4-megaton bomb would have deposited lethal fallout over Washington, D.C., Baltimore, Philadelphia and New York City…..
..Robert McNamara, the new secretary of defense, learned about the accident during his third day on the job. The story scared the hell out of him.”

Schlosser also identifies concerns over the way the weapons are managed:
“On February 26, 1988, Peurifoy3 wrote to the assistant secretary for defense programs at the Department of Energy and invited him to Sandia for a briefing on the dangers of the SRAM [Short-Range Attack Missile]. The assistant secretary never replied to the letter. The president of Sandia raised the issue with another official at the DOE, who suggested that the secretary of energy and the secretary of defense should be briefed on the matter. But nothing was done…. A few months later an independent panel was commissioned to look at management practices at the Department of Energy, and Peurifoy was asked to serve as a technical adviser….the panel wound up using the SRAM’s safety problems as a case study in mismanagement. [They] were shocked at the lack of attention to nuclear weapon safety and its implications. Almost fifteen years had passed since concerns about the SRAM were first expressed — and yet no remedial action had been taken. ‘The potential for a nuclear weapon accident will remain unacceptably high until the issues that have been raised are resolved,’ the panel said in a classified report. 
So what were the safety issues?
“The high explosives used in the primary of the SRAM were found to be vulnerable to fire. As the missiles aged, they also became more hazardous. The propellant used by their rocket motors had to be surrounded at all times by a blanket of nitrogen gas. When the gas leaked, the propellant became a ‘contact-sensitive explosive’ that could easily be set off by flames, static electricity or physical shock. If the SRAMs were poorly maintained, simply dropping them on the ground from a height of five or six feet could make them explode — or take off. ‘The worst probable consequence of continued degradation …is spontaneous ignition of the propellant in a way similar to a normally initiated burn,’ an Air Force nuclear safety journal warned.

For those of you thinking all of this is ancient history consider the following from Navy whistleblower William McNeilly. He recently leaked details of safety issues in Trident submarines. 
‘The Trident safety whistleblower, William McNeilly, says he has been dishonourably discharged from the Royal Navy to protect its public image.
In a nine-page report posted online, the former nuclear submariner attacks “military deceivers” and naval “spin doctors” for downplaying his allegations about multiple safety and security lapses.
“It is shocking that some people in a military force can be more concerned about public image than public safety,” he says.’ Guardian 17/6/15

  1. Sandia - an organisation set up as a research engineering and science laboratory currently operated by Sandia Corporation, a Lockheed Martin Company, for the US Department of Energy.
2.   SAC - Strategic Air Command

3.   Bob Peurifoy - a scientist who spent his working life devising ways of      making the handling of nuclear weapons safer.

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