Student’s Guide
Gentilly-2 Pro and Con – Society and Physics
Olivier Tardif-Paradis
Mathieu Riopel
Cégep Garneau
APP/Guide de l’élève 2
The Pros and Cons of the Gentilly-2 Power Station: A Made-in-Québec Debate
Background
From 2010 to 2013, a technical, scientific, social and economic debate raged in Québec, especially in the Gentilly region. The government had to make an important decision: repair or decommission the only nuclear power station in Québec. The government could not delay the decision, because the economic, technical and environmental risks were too high. The debate was fierce: on one side, the proponents of repair, and on the other, the proponents of decommissioning. Players such as nuclear physicist Michel Duguay, Thierry Vandal, the CEO of Hydro-Québec, Greenpeace militants and many others threw their weight into the battle. On both sides, the costs were significant – in the billions of dollars. It is easy to see why the Québec government could not ignore the issue.
Jean Charest’s Liberal government advocated repairing the power station, but after the provincial elections in 2012, Pauline Marois’ péquiste government came into power and opted for decommissioning, further heating up the debate. For example, during a very heated verbal exchange, the MNA for the Trois-Rivières region, Danielle St-Amand, was kicked out of the parliamentary commission on Gentilly-2 for inappropriate language. The debate became very emotional, since the issues were very pressing: 800 jobs, production of 675MW of electricity, specialized expertise, production costs higher than the national average, etc.
If you, as a citizen, were called on to take a stance in this socioscientific debate, which side would you have taken? Decommissioning or repair?
Perhaps at this stage you feel uncomfortable taking a stance. If so, that is not surprising. After all, before getting involved in a discussion, it is important to be well-informed.
A number of important issues need to be discussed with regard to this complex project. Since this is a physics course, one of the purposes of this activity is to learn the scientific vocabulary required to understand this socioscientific debate.
To this end, we will explore five themes in relation to the Gentilly-2 power station.
1) History of nuclear energy to Gentilly-2
2) Production of nuclear energy
3) Effects of nuclear accidents on human health
4) Nuclear waste and the environment
5) Alternative solutions
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Three-step Cycle
List all the relevant information you gathered when you read the problem. Based on this information, state what you need to know to solve the problem. As you discover new information, you should summarize and update the relevant information you have gathered and ask new questions.
List the Following:
What We Know / To Determine / SummaryPBL/Student’s Guide 9
History of Nuclear Energy to Gentilly-2
In 1905, the new ideas put forward by Albert Einstein strongly shook the foundations of physics as understood at that time. The relativity revolution turned our conceptions of space, time and energy upside down. Through this theory the famous equation E=mc2 was determined. This relatively simple equation suggests the counterintuitive idea that mass is related to the concept of energy. Mass is a physical manifestation with incredible potential energy!
In the early 20th century, through his research at McGill University, Ernest Rutherford demonstrated that almost the entire mass of an atom was contained in its nucleus. To make use of the energy predicted by Einstein, research efforts would have to focus there. That is what several scientists did, including Enrico Fermi. Then the potential of nuclear energy was tragically demonstrated to the entire world in the explosion of nuclear bombs in Japan, ending the World War II.
Further research allowed this formidable source of energy to be controlled so it could be used to produce electricity. This new source of energy attracted intense interest all around the world; it appeared to be the solution to humanity’s energy problem. Québec did not escape the general enthralment with nuclear energy. Several proposals for nuclear energy plants along the St. Lawrence River were made in the 1960s and 1970s. Finally the sole project to be commercially operated was Gentilly-2 (from 1983 to 2012). Gentilly-2 uses uranium-235 as its fuel.
The questions below will help you learn key parts of the theory of the atomic nucleus. You will need to understand these concepts in order to examine the more technical facets of the problem.
1) How is it useful to know that c2 = 931.5MeV/u? Prove the equation.
2) Find the average binding energy per nucleon in a uranium-235 atom, in MeV/nucleon.
3) What is the most stable nuclide in nature? Why? In your book, find the figure that best supports your explanation.
4) Why does uranium-235 have so many more neutrons than protons in its nucleus? Is uranium-235 the only atom with this characteristic? In your book, find the figure that best supports your explanation.
Energy Production
In 2014, humankind’s energy needs are colossal and rising faster than ever. Every country in the world is faced with energy production problems. The solutions adopted are many and varied, depending on the resources of each country. For example, in the United States, a significant proportion of primary energy comes from electric plants that burn coal, since the country is sitting on big coal reserves. This energy production method generates a lot of greenhouse gases, however, besides being non-renewable.
Québec can boast that it produces its energy using renewable, low-pollution sources. The land abounds with rivers that support hydroelectric power stations. In fact, 99% of the energy produced in Québec today comes from water. Despite the clear benefits of hydroelectricity, this energy production method is not without drawbacks. Recently groups of citizens have protested the construction of new dams to prevent the destruction of unique natural habitats.
Energy needs are enormous in Québec, though. Compared to other countries in the world, we rank as the second-highest consumers of electricity, at 26,060kWh per person in 2010.[1] Despite the real efforts made in the last few years to eliminate the waste of energy, our primary energy consumption has increased by about 35% in the last 30 years.
The problem is complex, since on one hand the growth in our energy consumption seems endless, and on the other, energy production methods all create some kind of problem. Furthermore, the energy consumption of the transportation system in North America is entirely dependent on oil, a very polluting energy source. Could nuclear energy be part of the solution to this monumental challenge?
1) What are the nuclear reactions in the Gentilly-2 power station called? Justify your answer by considering the reactants used to produce the energy.
2) Using the interactive animation at the website below, explain the factors that create a chain reaction. http://phet.colorado.edu/en/simulation/nuclear-fission
3) Here is one of the nuclear reactions that were produced at Gentilly-2.
In this reaction, a thermal neutron is projected on to a uranium-235 atom. Find the missing nuclide in the nuclear reaction.
4) Calculate the energy released by the reaction in electron volts.
5) Knowing that the set of fission reactions of a uranium-235 nucleus releases 190MeV, how many kilograms of uranium-235 would Gentilly-2 need to meet its energy needs for one year? We know that a nuclear power station is only 32% efficient
Effects of Nuclear Accidents on Human Health
Several reactions that occur in the heart of a nuclear power station produce radiation. If the radiation is not contained, it can spread out into nature and disrupt the function of living cells.
In 2011, a global catastrophe occurred. After a powerful earthquake, a tsunami swept up over the coasts of Japan. On its route, it seriously damaged the Fukushima Daiichi nuclear power station. Radiation from the damaged power station leaked out into nature.
The catastrophe at Fukushima Daiichi was unfortunately not unique. In 1986, the city of Chernobyl in Ukraine was the scene of an enormous catastrophe after the explosion of a reactor in its nuclear power station. This unprecedented disaster led to the deaths of thousands of people, and radioactive emanations spread all across Europe. The region closest to Chernobyl is still uninhabitable today due to the strong radioactivity that persists there.
Could an accident similar to what happened in Japan have happened in Québec with the Gentilly-2 power station? What would have been the effect of such a disaster on the health of Quebecers? Was there a real danger? Can even the smallest dose of radiation cause a risk of cancer? The following questions will help you consider this aspect of the problem.
A few sources of useful information:
http://en.wikipedia.org/wiki/Ionizing_radiation
http://en.wikipedia.org/wiki/Nuclear_fission_product
1) Is uranium-235 radioactive? Are all the by-products generated by the nuclear reaction at Gentilly-2 radioactive?
2) What is alpha decay? Is it dangerous?
3) What is beta decay? Is it dangerous?
4) What is gamma decay? Is it dangerous?
5) What is a becquerel? What is a sievert? What is the connection between them?
6) On March 26,2011, around noon, the Japanese Nuclear Safety Agency published the iodine-135 levels taken the day before by the Tokyo Electric Power Company downstream from the power station’s southern overflow valve into the sea: 50,000Bq/litre, or 1250 times the legal limit for the ocean (40Bq/litre)[2]. As well, the concentration of cesium-137 (which has a half-life or radioactive period of 30 years) was over 80 times the legal limit.[3]
These two isotopes are among the most dangerous for human health. Which of the two will exceed Japanese standards for the longest?
Nuclear Waste and the Environment
The production of energy by thermal power stations that use fossil fuels releases huge quantities of greenhouse gases into the atmosphere. These gases have a considerable effect on the planet’s climate. Nuclear power stations, which emit no greenhouse gases, could be an interesting solution for combatting climate change without having to reduce energy consumption. But nuclear power plants produce another type of waste. The nuclear reactions that occur in the station product a panoply of radioactive isotopes that require safe disposal.
The transportation and burial of large quantities of radioactive waste creates a host of environmental, economic and political problems. For example, in 2008, the Nuclear Waste Management Organization (NWMO) started looking for a single burial site in Canada. Québec was one of the provinces the NWMO was looking at, “in the interests of fairness.” Indeed, with Gentilly-2, Québec was one of only three Canadian provinces with a nuclear power station. At the beginning of the process, the total cost for finding a burial site was projected to be $5-6 billion.
1) In the following list of types of radioactive waste produced by the nuclear fission reaction of uranium-235, find three isotopes for each category.
a. Extremely long-lived fission products, existing in the natural state. Not very radioactive.
b. Very long-lived fission products, off the historic scale. Moderately radioactive.
c. Medium-life fission products, historically manageable. Very radioactive.
d. Discuss the environmental impacts of these different fission products. Which type do you think is the most problematic for the environment?
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2) During the nuclear reactions produced at the Gentilly-2 plant, uranium was transformed into energy and other elements.
a. At Gentilly-2, it took a year to produce about 23kg of strontium-90. This radioactive isotope was then placed in storage. After 10 years of storage, how many strongium-90 nuclei are left?
b. Cesium-135 is a radioactive agent produced by a nuclear power station. After 50 years of storage, will its decay rate have diminished appreciably?
Summary
If you take your role as a citizen of Québec seriously, you cannot be indifferent over the debate about the Gentilly-2 power plant. Ideally, now that you know a little more, you can take a position.
You should know that either position entails consequences. For example, if you propose closing Gentilly-2, there is the problem of growing demand for electricity. Remember that in this debate, the status quo is not acceptable, since the power station requires major repair work at a very high cost. Here are a few different scenarios that could be considered:
· Renovate Gentilly-2
· Build new hydroelectric dams
· Build a power station that uses combustible fuel, like coal
· Stop selling electricity outside of Québec
What do you think of these various scenarios? What are the financial, social and environmental impacts of these options? What other possibilities could be considered?
Now choose your stance and write a defense of your position. Draw on the science you learned in this activity.
Additional Points of Reflection
What is the predominant argument?
What is your position?
Has your approach to analysing the debate changed? Is your position more nuanced?
What issues were not considered in this activity that might help you make your decision?
Appendix – Possible Alternatives
Québec society is very privileged in terms of the level of energy it has available, because it can count on the power and number of its rivers to produce electricity. In fact, in Québec, just 1% of electric energy comes from sources other than hydroelectricity. And only Iceland can meet almost all of its electricity and heat needs using geothermal energy, another form of renewable energy. But this situation is nowhere near the norm in other countries around the world.
For countries that cannot count on extensive access to renewable energy, thermal (oil or coal) and nuclear power stations are currently the only available options. Meanwhile, climate change, which can no longer be denied, requires us to reduce global greenhouse gas emissions by half within 30 years.