Going Nuclear

Nicole Jardine | originally written in 2005

Most people choose whether to attend a given college based on its academic record, its prowess in football, or at least its fame for wild parties. Me? Nah. There were two academically-irrelevant motivators for choosing the University of California at Irvine. Number one: there is a freshman dorm community named Middle Earth (with halls like Lothlorien, The Shire, and so forth), appealing strongly to my nerd core. Number two: there is a bona fide nuclear reactor on campus. Which... also appeals strongly to my nerd core.

Did I even end up living in the Middle Earth dorms? Nope. Does my major have anything to do with chemistry or particle collisions? Of course not. But flying by the seat of my pants is simply how I do things, and when I enrolled I made it my eventual goal to see the reactor.

The Campuswide Honors Program (of which I was a part) had organized a few tours, in small groups of 15 or so people, to come face-to-face with the reactor. My name was among the first on the list, and a few weeks later I was confirmed to go.

When the day arrived, my excitable peers and I met outside one of the many large buildings in the Physical Sciences area of campus. After milling uselessly around for a few minutes we entered the Physics building, encountering some construction en route to the elevator to the nuclear lab. (In retrospect, construction so near a nuclear device ought to have caused at least a little alarm.) We crammed ourselves into the elevator. It creaked and groaned - another strike in favor of the building's aged creepiness. Not a single student spoke on the elevator, and finally we arrived safely on the fifth floor. It took a bit of confused wandering to find where we wanted to go – they don’t have giant signs that say “NUCLEAR REACTOR THIS WAY,” though it would be ever so helpful – but eventually we found the desired room. Still subdued in the unnaturally silent building, one of us knocked on the door.

A split second later we all jumped when a graying, bearded man briskly swung through the door. He looked taken aback by the quantity of us that had shown up. I don’t know why he was so surprised – it’s a nuclear reactor! Really, who doesn’t want to play with radiation?

He introduced himself as Dr. Miller, and after laying down our backpacks we filed into the first room. It was a messy lab space, complete with whiteboard (filled with haphazardly scribbled calculations and diagrams), bookshelves, unlabeled boxes, towers of papers, and fun little computer screens and dials. (The latter are known in scientific jargon as “instrumentation”). The actual reactor was in the adjacent room, and I definitely wasn’t the only one peering inquisitively through the glass window trying to get a glimpse at it. Our attention was soon drawn back to Miller as he gave an overview of the reactor and the research it’s generally used for.

The reactor was built in the 1960s, and it first became critical (translation: “started to work”) in 1969. It hasn’t been changed much; the instrumentation is very ancient stuff-you-see-in-space-movies-from-the-70s gear. In a nutshell, nuclear reactors are able to start nuclear chain reactions in a controllable environment – and of course, control is good when you’re dealing with the very same power that drives nuclear bombs. To generate power, the reactor propels high-energy neutrons (the neutrally-charged fundamental particles that, along with protons and electrons, comprise most atoms) at particles of a specific isotope of enriched uranium (U-235). The neutrons collide with the uranium, and, because uranium is such a large element composed of lots of protons, neutrons, and electrons, it splits into smaller particles. It also releases gamma rays, alpha particles, and beta particles (that’s the “radiation” part). This process of splitting is known as fission, and it’s how nuclear power plants generate power.

Dr. Miller started pushing some buttons and turning some dials (see? Straight out of the 70s) and we heard clunking noises coming from the room next to us. To get the reaction going, you start firing some neutrons at the uranium to get them colliding. After a certain point, the reaction starts doing this faster and without any help – this is known as “going critical,” which basically means that it’s now self-initiating and you’ll need to intervene to stop it. When the reaction started, it generated about 7 watts of power – not nearly enough to power your average lightbulb. But when it started going critical, there was a sudden rise in the energy produced, up to 250 kilowatts (25000 watts) of energy. In a nuclear bomb, this order of magnitude is reached not in minutes, as we were watching in the lab, but in hundredths of a second. So how do we stop our reaction? You can turn another knob to adjust control rods made of boron, an element that absorbs neutrons well. These boron rods control, slow down, and eventually halt the chain reaction.

At one point during this demonstration there was an odd noise and something happened that caused Miller to muse speculatively, “Well, that’s never happened before.” But nothing exploded and my uterus hasn’t fallen out, so presumably it was nothing bad.

Then, the best part: going into the room to see the reactor!

We didn’t have to put on any protective goggles or radiation gear – it seemed safer, for some reason, than walking around in a chemistry lab. And for all I know, maybe it is. We fanned out to circle a waist-height rail that protected people from falling into a pool of water. This pool, which is circular and about fifteen feet in diameter, is 25 feet deep and acts as a protective barrier against radiation. The actual nuclear reactions occur at the bottom of the pool. We could see various pipes going down into the pool, and at the bottom was a donut-shaped soft blue glow, made more striking when Miller dimmed the lights. This light is caused by the nuclear reaction. It’s quite beautiful, although it probably isn’t a good idea to jump in and chase it. While you’d be okay if you just fell in and floundered on the surface, Miller assured us, most definitely Bad Things would happen were you to insist upon swimming down twenty five feet where the radiation was occurring.

After Dr. Miller shut down the reactor we walked around the room to examine what else the lab did. He demonstrated the use of a gamma-ray spectrometer. This is a neat little device; you put some substance (an unknown rock, someone’s hair, whatever) in a small thumb-sized tube and place it in the machine, which bombards it with radiation to analyze its mineral content. This technique can identify substances, and is commonly used in archeological or crime scene analysis. (You know all those CSI scenes where they talk about hair identification? Although all hair is made of protein, everyone has hairs with a uniquely identifiable mix of substances, sometimes including mercury or even gold, that may be based somewhat on genetics and diet. By comparing samples of hairs directly from your head to a sample taken from a crime scene, the spectrometer can determine with good accuracy how likely the hair at the scene is yours.)

Time to exit the reactor room. We walked through a machine that resembles a metal detector but actually detects your body’s level of radiation. We were all safe, and so was my camera. Dr. Miller shared an anecdote about a previous tour in which one guest was toting around a camera with a high-quality lens containing, unbeknownst to him, radioactive glass. While the glass was great for optics and refracting light, it was also, most unfortunately, giving off detectable and biologically harmful levels of radiation. Bummer.

For some closing remarks, Dr. Miller discussed some of the research done by the lab in its lifetime. It’s analyzed tuna fish from the late 1800s and the 1970s, and found mercury levels in the two samples to be surprisingly similar. (That said, mercury levels in fish have definitely increased in the last few decades.) The lab has also analyzed bullet fragments from John F. Kennedy’s assassination. Some experts had suggested that Kennedy was shot by multiple people, but analysis revealed that the fragments had more than likely come from the same bullet.

Spectrometry also has historical uses. Back in the day, when you died your barber was allowed to cut your hair and sell it for any price he pleased. This is how some scientists were able to get their hands on some of Napoleon’s hair. When researchers used spectrometry to analyze the mineral content of Napoleon’s hair they found high levels of arsenic distributed throughout the length of the hair, suggesting prolonged exposure. There are multiple possible explanations. Firstly, wine was often laced with arsenic, so any wine consumer would also ingest trace amounts of the toxin. Secondly, Napoleon may have had STIs for which the treatment included arsenic. Finally, it turns out any number of materials contained arsenic at the time. Therefore it’s within the realm of possibility that Napoleon may, just on special occasions, have licked wallpaper.

All in all, an enjoyable tour! It almost made me want to be a Chemistry major.

….Almost.