How is a nuclear reactor used for science? - Transcript
If you speak to my friends, they will tell you that it is unlikely that I would urge others to “have faith in humanity”. I am perhaps too preoccupied with some of the disappointing behaviour I see in the world. In spite of my experiences with people elsewhere though, my workplace has brought me to see that there is good reason to trust in the generation or two coming next.
Slide #1 NRU Reactor Hall
This is where I work. You can see some people there, to show you the scale. It’s the size of a cathedral. It is the NRU research reactor - a nuclear reactor used for science. I’d like to share with you some of the remarkable stories of imagination and achievement that came about because of NRU. Who knew that Canada’s most productive science facility was tucked out of site not far up the valley from Ottawa.
So there are two issues immediately there, “How can I make such a bold statement that NRU is the most productive science facility Canada has ever built?” and on a more basic level, “What does N.R.U. even stand for?” Both questions have easy answers. NRU is short for National Research Universal, an odd but apt name for a facility that has done so much across all avenues of science: physics, chemistry, biology and engineering, truly a universal facility. But everyone who works there just calls it NRU. In terms of what it has done for Canada and the world: NRU provided the foundation of knowledge which launched and sustained two multi-billion dollar, international industries for decades, one in the energy sector, the other in the health sector. NRU has directly affected hundreds of millions of people’s lives and pioneered a new branch of physics which was recognized with a Nobel Prize (more about all that in a moment). There are several other great science facilities across the country that together make up Canada’s national science infrastructure, but NRU is simply outstanding.
How is a nuclear reactor used for science? How does splitting atoms help anyone?
Slide #2 Atoms
I learned in high school that everything in the world is made from atoms, like tiny building blocks. There are just 92 different types of atoms. We give them all names like calcium, nitrogen or sodium. Each atom has a nucleus, made of protons and neutrons, then flying around the nucleus are tiny electrons. The word “nuclear” just means “about the nucleus”. Chemistry is all about joining atoms together: two Hs and an O make H2O, but in a nuclear reactor we are dealing with what is inside atoms.
Nuclear reactors use one specific atom, the heaviest one of all: uranium. Uranium atoms have a special property. If you add a neutron to a uranium atom, it becomes too heavy. It is not happy in that state, and it splits apart into two halves. Each of those halves is an atom about half the size of uranium. Two or three neutrons and some energy are also released.
Slide #3 Fission
Well, if a neutron was needed to make this “split” happen, and now we have just made two or three more neutrons, the process can repeat over again and go on and on: adding neutrons to uranium atoms, splitting them apart and producing more neutrons.
There are only two more pieces needed. When a uranium splits apart the neutrons which fly out are moving too fast to join onto another uranium. Those neutrons need to bump into something and lose some speed. The best objects to do that are small atoms, almost the same size as a neutron. Hydrogen is ideal, and there is lots of hydrogen in H2O. Finally, to stop the reaction another material is needed that will soak up neutrons.
That is what the inside of NRU looks like: we have some uranium in long rods. Those are surrounded with water in a big tank, and we have some rods made from cobalt which soak all the neutrons up when we want the reaction to stop.
So although you can see NRU is a vast science facility, at its heart it is remarkably simple: a big tank of water which makes trillions of neutrons.
In 1957 when NRU began operating, Canada had this new, amazingly powerful tool. The designers did not pretend they could guess what people in the future would use it for, so they just made sure there were many access holes for a wide variety of experiments to use the neutrons. NRU was far more powerful than smaller research reactors that had preceded it, though I have to say that innovation started as soon as those early research reactors became available: NRU was the culmination. I am always amazed by the stories of what scientists and engineers were able to accomplish when this tool was put into their hands. Three tremendous stories of innovation help illustrate that.
When earlier reactors, and then NRU, became available to the scientists of the day one exciting idea that surfaced was: “now we can make isotopes!”
Slide #4 Isotopes
The nucleus of an atom is a clump of protons and neutrons. Neutrons don’t do much. Mostly they affect the atom’s weight. Add a neutron, the atom gets heavier. It is still an atom of iron or oxygen or carbon, just a heavier version. Two atoms that are the same but only differ in weight are called isotopes. When NRU is operating there are a billion neutrons in each cubic centimetre inside the core, so if you put a lump of something in there, it can capture neutrons and its atoms will turn into heavier atoms. The reason scientists wanted to do that is: some isotopes are not just heavier than their cousins, they are unstable. Because of that extra weight, they want to spit out some energy and settle down to a more stable state. That energy is an x-ray, and scientists saw two really useful ways to use x-rays to help patients.
In NRU we can make isotopes that produce quite a low energy x-ray, and doctors inject those into patients and use the x-ray to create an image, a CAT scan, which helps to diagnose a wide range of illnesses. In a normal year NRU can produce enough to help more than 5 million patients around the world, a huge impact helping all those people and their families.
NRU also makes isotopes, like cobalt-60, which emit a very strong x-ray which will destroy any living cell it shines on. Cobalt-60 from NRU is used to kill cancers, and the machines that have been sold by Canadian companies have a major impact in Africa and the developing world where sixteen “one-six” million patients a year benefit from a technology that was pioneered here in Canada.
Over its time in operation, NRU has supplied well over half a billion patient treatments to people in more than 80 countries. Half a Billion.
Slide #5 NRU Reactor
There was a second, entirely different idea, taking shape amongst scientists and engineers when NRU was being designed and built, and that was to use the heat from a nuclear reaction to boil water, to make steam, to turn a turbine and turn a generator to make electricity. The challenge that stood before them was that no one understood fully the harsh conditions in the core of a nuclear reactor, with billions of neutrons flying around. When a neutron hits an atom in the steel or concrete holding the whole structure together it could move that atom or cause a reaction, so it would be important to choose the right type of construction materials that could remain strong in that environment.
Research reactors experience those harsh conditions, but nuclear reactors that generate electricity are much larger and very expensive machines to build - like a hydro dam, but once they operate they produce constant cheap and reliable electricity for decades - a similar type of investment to a hydro dam. But if you choose the wrong materials the reactor may be inoperable in a short time and the big investment is wasted. So engineers used NRU, and its predecessor, as a test bed. They took samples of materials and put them into NRU, let those samples experience the harsh conditions of the fission reaction, then used that knowledge to choose the best materials for building the colossal reactors that generate electricity. In the decades after, NRU has continued to produce knowledge that solved the biggest challenges for these literal power-houses of the Canadian economy.
Because a group of imaginative scientists and engineers used NRU to answer some very practical questions, Canada was able to build a fleet of nuclear reactors that generate a sixth of our country’s electricity, in Ontario more than 50% of our electricity comes from nuclear power, all without generating greenhouse gas.
The last story I’d like to share with you is how here in Canada a whole new branch of science was pioneered.
Slide #6 Bert Brockhouse at a neutron spectrometer
In 1950, Bert Brockhouse, a bright young man, who served in World War II as a sonar operator, found himself at Chalk River Laboratories where NRU was under construction and its predecessor, the NRX reactor, was already operating. Working in these research reactors, Bert was part of a team who designed and built specialized machines that could shine a beam of neutrons onto a sample of material, then measure how those neutrons scattered off the molecular structure of that sample. It was a brand new technique that showed scientists how materials were knitted together at the molecular level. But here’s the magic: the technique can be used to analyze almost any material, metal, glass, plastic, semiconductor, ceramic, gel, or even the materials we are made of: biological material. All he needed was the powerful NRU reactor and his imagination did the rest.
Bert Brockhouse won a Nobel Prize in Physics for that innovation, in 1994, by which time almost every developed country had a research reactor which was used for materials research, because it is such a versatile technique that can drive advances in many areas of human endeavour: materials are literally everything around us. Today in NRU those diverse experiments happen every day, on a host of different materials. There were only a handful Canadian Nobel Prizes in the 20th century, but NRU enabled one of those. Why? Well for two reasons because NRU was available, with all its tremendous power and capability, and because Bert was an imaginative, smart guy.
Slide #7: NRU Team
It is these stories of breakthrough and innovation, those from history, but those happening around me every day, that make me proud to be a member of the NRU Reactor team, and here is some of that team (we work in shifts 24/7 so we can’t get everyone in a single photograph). Our round-the-clock operation means the science and innovation continues from the bright minds who have access to this powerful science facility.
That is what gives me cause to be hopeful in the coming generation. Because my team operate NRU today, scientists, researchers and students who were not even born when it was first built, come from around the world through our front door every week, and have ideas for new experiments to:
- give Canada thousands of years of electricity without producing greenhouse gas
- deliver the next generation of life-saving medical products for millions of patients worldwide
- make a breakthrough in understanding a new material which will...?
Which will what? Make possible a new heart implant, or supercomputer, or supersonic train: I don’t know. (Those first two examples are real though - those experiments have been in NRU this year)
Slide #8: Repeat of Slide #1
NRU has proved what happens when we invest in a national science facility then make it available for everyone to use. As a country we made an investment which, while substantial, was not out of scale with other government spending - it’s the same as one big city hospital, or four F-22 fighter jets. It has paid us back in so many ways, because of the richness of the human imagination. We have delivered more than half a billion patient treatments. Billions of tonnes of greenhouse gas have been avoided because of NRU, and that was because of the thousands of students, professors, scientists and engineers that had access to a powerful research facility.
NRU will come to the end of its operating life in the Spring 2018, with 60 years of great achievements standing as a proud record.
I have faith that the new scientists starting their careers today will continue to amaze us, and deliver technology that has international impact, as we as a country continue to provide them with powerful capable scientific tools like NRU.
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