Xenon-135: anticipating knock-on effects

Demons in Digital Gold, Part 8

not actually in the periodic table of elements, being an bizarre isotope of Xe and all

The plan was to power the Hanford reactor up to 9 megawatts and maintain that level for a while on the afternoon of 26 September 1943. The next day they would increase the power level until it reached the 250-megawatt level for which it was designed. The next morning, however, the reactor began inexplicably to lose power. By midafternoon the operators were having trouble maintaining nine megawatts. By the end of the day, the reactor was — for all intents and purposes — dead. Panic gripped everyone in the reactor building. If this reactor failed to do its job, it would be a crucial logjam for the entire Manhattan Project.

— The Last Man Who Knew Everything, The Life and Times of Enrico Fermi

Enrico Fermi oversaw the first nuclear fission chain reaction on 2 December 1942, in the CP-1 reactor built on a squash court under the stands of the University of Chicago football stadium. That was an epic achievement, made possible by Fermi’s unmatched skills in theoretical and experimental physics.

His peers described him as “the last man who knew everything,” because of his mastery of EVERY aspect of physics at the time: astrophysics, condensed matter, geophysics, particle physics, and quantum physics.

He contributed to the Manhattan Project from its inception. In addition to the massive accomplishments attributed directly to him, Fermi would be the go-to problem solver at Los Alamos for physicists and engineers stuck on particularly thorny issues.

Enrico Fermi was THE MAN.

Just nine months after the world’s first nuclear fission chain reaction, Fermi directed the construction of the far more powerful reactors at Hanford, OR. These reactors would produce the plutonium critical (pardon the pun) to the Manhattan Project. As described in the quote atop this blog post, shortly after reaching criticality (producing a sustained chain reaction) the first reactor ground to a halt. And nobody — Fermi included — could explain why. This was a terrifying embarrassment for the man that LITERALLY knew more about nuclear fission than anyone in the world.

Time and again, the Hanford reactor would reach nine megawatts and then lose power. John Wheeler, the physicist in residence at Hanford, thought that the pattern might be explained by “reactor poisoning”: uranium fission by-products could absorb neutrons out of the chain reaction, slowing or even stopping the reactor from working.

Fermi and his team studied neutron absorbers a year earlier. The identified which elements were particularly “good” absorbers, and discovered that cadmium was one of the most potent neutron absorbers. But cadmium could not be the culprit at Hanford, as it was not a uranium fission by-product.

Wheeler consulted a list of isotopes that might be created in uranium fission reactions, and suggested that xenon-135 could explain reactor’s behavior.

Fermi made some rough calculations of the ability of xenon-135 to absorb neutrons. He discovered, to his and everyone else’s astonishment, that its ability to absorb neutrons was vastly higher than any element previously studied. The calculations suggested that this extremely rare form of xenon was one hundred thousand times more potent than cadmium.

— Ibid

Imagine that. A by-product of NORMAL operation, capable of interrupting normal operation, FIVE ORDERS OF MAGNITUDE better at doing so than everything previously anticipated. Talk about an “unknown unknown” …

This is not a story of Nobel laureate Enrico Fermi missing a facet of a nascent technology. Fermi was surrounded by a team of brilliant engineers and physicists, some of whom would go on to win Nobel prizes themselves. That team had thoroughly studied neutron absorption, element by element, isotope by isotope. They had not studied xenon-135.†

This is a story of unanticipated knock-on effects.

I’ve playfully referred to such unanticipated knock-on as “demons.” Hence the name of the series, Demons in Digital Gold. We’ve examined a breadth of potential knock-on effects, by-products of blockchain technology and cryptocurrencies.

• Dangers of holding cryptocurrencies on an exchange
• Risks posed by exchanges to the cryptocurrency market
• Vulnerabilities in using cryptocurrencies as a Store of Value
• Threats and mitigations for your own personal wallet
• The lack of remediation inherent in blockchain technology
• Risks posed by competitive obsolescence

Here begins a series exploring the pros and cons of cryptocurrencies. “That would have made a perfectly reasonable title,” you’re thinking, “simple and easy to understand: Exploring the pros and cons of cryptocurrencies.” Yea, sure, but experience has taught that dramatic titles pique curiosity and motivate people to expend the energy of clicking from Twitter to Medium.

So we’re sticking with “Demons in Digital Gold” (DiDG) for the duration.

— Demons in Digital Gold, Part 1

“So you’re changing the name of the series to xenon-135?” you wonder. Absolutely not. We’re riding the DiDG horse that got us here.

“So you’ve spent an entire blog post on a historical digression?” you posit. That would be an entirely worthwhile endeavor, if it motivated just a handful of you read the outstanding biography of Enrico Fermi: The Last Man Who Knew Everything, by David Schwartz.

Xenon-135 is a new effort

Anticipating knock-on effects in blockchain technology and cryptocurrencies. An effort with its own website! [ed: a single-page static website, duly noted, for the time being.] Stay tuned for developments and get in touch with me should you have a need a hand anticipating knock-on effects.

Next in the series …

Back to our normally scheduled programming

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Copyright © 2018 Bruce Kleinman. All Rights Reserved.

† Resolving the reactor poisoning at Hanford

Xenon-135 is a uranium fission by-product — seen for the first time in the Hanford reactor because of its higher power level — in EVERY nuclear reactor. Once Fermi and Team had identified the source of the reactor poisoning, they knew that its fairly short half-life of 9 hours would dissipate the xenon-135.

Thanks to over-engineering, the Hanford reactor had “extra” uranium that was employed to drive the reactor over the troublesome nine megawatt level, all the way to its design target of 250 megawatts. The effect of the extra uranium counter-balanced the effect of the xenon-135.

History doesn’t repeat itself, but it TRAGICALLY rhymes

Decades later, a 1000 megawatt nuclear reactor underwent maintenance. An ill-conceived set of experiments were to test the reactor at 75% power. Inexplicably to the reactor’s operators, power dropped lower and lower. Control rods were slowly removed — in order to increase power — to no avail.

None of the operators understood that an “equilibrium concentration” of xenon-135 (produced during normal 1000 megawatt operation) was poisoning the fission chain reaction at the lower power levels.

Power fell to a scant 30 megawatts. Intending to restart the reactor, the operators completely removed the control rods. The xenon-135 gas escaped. Reactor power jumped so quickly that steam bubbles formed in the cooling water, defeating the reactor’s ability to dissipate heat. Power continued to increase precipitously, eventually reaching a disastrous 30,000 megawatts. The operators SCRAM’d the reactor, an emergency shut-down procure that dropped all of the control rods into place. It was too late.

The date was 25 April 1986. The place was Chernobyl, Ukraine.

Copyright © 2018 Bruce Kleinman. All Rights Reserved.