Fukushima: Nuclear Disaster. Izzy Burke, Roxy Paleo, Tyler Bailey, David Han, Jane Horner

Transcription

1 Fukushima: Nuclear Disaster Izzy Burke, Roxy Paleo, Tyler Bailey, David Han, Jane Horner

2 What is nuclear energy? Nuclear energy is nonrenewable yet is still considered sustainable due to the expected amount that is readily available for use (supply for the next 100 years) (Nuclear Energy).

3 Why do governments invest in nuclear energy? -Nuclear power is a carbon-free source of energy and is therefore more eco-friendly than most other types sources of energy production (Nuclear Power) -Nuclear power costs less than two cents per kilowatt-hour of maintenance and operation which is relatively cheap in the world of fuel (Nuclear Power)

4 Does It Have A Future? -Nuclear energy has a promising future concerning the design flaws that have led to recent disasters as designs grow more efficient and safer (Small Modular Reactors produce 3/10 of the energy used in traditional reactors but retain natural cooling features in the absence of power and also reduce the risks of a fallout) (Nuclear Power) -Although it is not seen as a certain solution for combating climate change and cutting greenhouse gas emissions, it is a cleaner and more affordable route aimed at achieving said goals (Nuclear Power)

5 How does a nuclear reactor function? 1) Produce electricity through boiling water to produce steam and spin turbines through nuclear fission (splitting of atoms) (Nuclear Reactors) 2) Uranium fuel is compacted into ceramic pellets and then packaged and suspended in vertical tubes (Nuclear Reactors) 3) Uranium-238 is the main component however Uranium-235 is also used and is also less stable, resulting in a higher energy yield (Nuclear Reactors)

6 1) 2) 3) 4) Process of fission splits neutrons from nuclei, creating collisions with other atoms and thus creating a chain reaction of fission with the fuel tubes. This process is self sustaining due to the high amount of energy produced. (Nuclear Reactors) 5) Rods are placed in water to heat it and produce steam and control rods are also placed inside the reactors to help accelerate or decelerate the reactions through insertion and withdrawal in the tubes (Nuclear Reactors)

7 What Is Radiation? Energy traveling through space - World Nuclear Association (an international collective of corporations and vendors who specialize in providing materials and waste management for nuclear power facilities across the globe) Particle physics perspective: radiation is the release of energy in the form of electromagnetic waves or subatomic particles Undergone by the nucleus of an atom in order for it to achieve a more stable state of existence

8 Why Does Radiation Occur? Radiation may happen naturally, or spontaneously, meaning the reaction will inevitably occur without instigation from an outside source of energy Key phrase: inevitably, they occur. Spontaneous does not mean fast or immediate. Thermodynamic spontaneity = if a process involves transferring energy to create more favorable conditions (i.e. a state of greater stability), then that process will eventually happen, however long it takes This idea of spontaneity being tied to thermodynamic conditions rather than simply time helps us understand why radioactive materials continue to decay for immense periods of time after the initial nuclear reactions take place

9 What Forms Can Radiation Take? Image credit:

10 The Health Physics Society lists two general categories of radiation which all existing forms fall into: ionizing and nonionizing radiation 1. Non-ionizing - lower frequency and longer wavelength. particles being emitted from non-ionizing radiation are not The Health Physics Society is an organization of scientists, damaging at low dosages. health professionals, nuclear This is why it s completely safe technicians, and policy makers whose goal is to promote the to listen to the radio every day, or to safe usage of radioactivity keep a microwave in your dorm room; these all represent low-frequency forms of radiation.

11 1. 2. Ionizing - high frequency and shorter wavelength. Large amounts of energy released in the form of high-speed subatomic particles ejected from atomic nuclei Identity of these particles depends on the form of radiation taking place Alpha radiation is the ejection of alpha particles, aka helium nuclei Beta radiation ejects high-speed electrons, or beta particles from nuclei Gamma radiation and x radiation (aka xrays ) are highly penetrating forms of radiation where a photon (light in particulate form) is released from the nucleus Image credit:

12 What s The Difference? Ionizing radiation is more harmful than non-ionizing! The energy contained in the emitted particles is exponentially greater These particles travel at high frequencies and small wavelengths, so when they collide with nearby atoms and molecules, they have the capacity to rupture their stability (either by knocking electrons out of their orbitals or cleaving neutrons/protons from nuclei) Causes neighboring particles to develop a charge, thus becoming ionized and, as a result, unstable

13 Nuclear radiation is a form of ionizing radiation, and involves a process known as radioactive decay. Image credit: Radioactive or nuclear decay = when extremely heavy or unstable nuclei spontaneously break apart while releasing large amounts of energy Energy is released in the form of fast-moving subatomic particles (recall alpha and beta particles, neutrons). In fission reactions used in nuclear power plants, we are essentially moderating a naturally spontaneous RXN in order to capitalize on the released energy it releases.

14 As seen in Fumiya Tanabe s 2012 analysis of the Fukushima reactors meltdown in the Journal of Nuclear Science and Technology, the reactor cores were predominantly composed of uranium dioxide (appx tons in Reactor Unit 1, tons in Unit 2/3). Image credit:

15 Why Uranium? Reactor cores are selected on the following criteria, as described by Professor W. Dean Harman, Chemistry Department Chair at the University of Virginia: 1. Relative abundance in the earth s crust (must be accessible) 2. Rate of decay (must have a long enough half-life to be usable, yet short enough for the nuclear decay process to be worthwhile) 3. How well the sample absorbs neutrons to continue the cascade process

16 The naturally heavy isotope (such as ²³⁴U, the isotope used in Fukushima) spontaneously ejects a neutron in an attempt to reach a more stable form This neutron is then captured by surrounding atoms, causing their nuclei to split and expel a neutron as well Process continues in a cascade effect, producing exponentially greater amounts of energy as each fission triggers more nuclei to split

17 Nuclear power In Japan

18 Current operation of nuclear power stations in Japan - 42 are operable - 24 await approval for restart - 2 restarted in August and October 2015 A map of the locations and number of the reactors in Japan.

19 Types of nuclear reactors - Light water reactor(lwr) - Heavy water reactor(hwr) - Graphite moderated reactor(gmr) - Fast breeder reactor(fbr)

20 All six reactors in the Fukushima disaster are BWRs

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22 Comparisons to Chernobyl

23 What is the Chernobyl disaster? Chernobyl is the name of a city in Ukraine It was abandoned after the Chernobyl Nuclear Power Plant explosion A systems test at nuclear reactor number 4 failed Explosion and fire released large quantities of radioactive elements into the atmosphere Chernobyl had no containment structure This did not stop the trajectory of radioactive materials into the air Fukushima nuclear reactors: built on granite foundations

24 Level 7 nuclear events Chernobyl Fukushima

25 Radioactive emissions terabecquerel- measure for radioactive materials A trillion becquerels Chernobyl leaked 5.2 million terabecquerels of radioactivity Fukushima total is unknown-radioactive contamination still leaking

26 Iodine-131 and Caesium-137 Iodine-131 Decays quickly-half life of 8 days Caesium-137 Half life of 30 years Radioactive elements carried by windradioactive penetration through skin and consumption

27 Aftermath 30 years since the Chernobyl disaster 985,000 more predicted deaths due to cancer in the future 5 years since the Fukushima disaster No accurate comparison of the aftermathfukushima links to cancer still unknown Latency time for radiation health problems can be decades

28 TEPCO s involvement TEPCO- Tokyo Electric Power Company Accused of covering up the severity of the disaster at Fukushima Nuclear meltdown was to be declared if the damage to the reactor core exceeded 5% A 2012 report played down the safety risks out of fear that additional measures would lead to a plant shutdown and increase public anxiety

29 Measurement of Radiation Radiation is measured using the SI system, the millisievert (msv) This is the average accumulated background radiation dose to an individual for 1 year, exclusive radon, in the US 1 msv is the dose produced by 1 milligray (mg) of radiation

30 Effects on community and environment

31 Radiation Levels Japan changed their official safe radiation exposure levels The land within a 12 mile radius of the plant (about 230 square miles) were found to be too radioactive for human habitation

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33 Effects on economy Estimated total economic loss between $ billion (within 310 square miles of exclusion zones) Evacuees have received little to no compensation to cover cost of living

34 Decontaminating the exclusion zone Once radioactive Cesium enters an area it will be found everywhere Contaminates water, soil, plants, and animals Attempts to decontaminate exclusion zones have failed Presence of snow and rain carry the chemicals down hills and mountains and back into uncontaminated zones, recontaminating them

35 Discharge of Radioactive Material Produced largest discharge of radioactive materials into the ocean in all of history Fishing is still banned off the coast of Fukushima today

36 Fukushima reactors and Spent Fuel Ponds Today The reactors and spent fuel ponds are still not stabilized Reactors 1, 2, and 3 still discharge radioactive gases every day Uranium core of reactors have completely melted down Still produce large amounts of heat and radiation every day

37 Reactor #4 Reactor #4 was severely damaged and currently holds a spent fuel pool with 1,532 nuclear fuel assemblies Contain 10 times more radioactive cesium than was released in Chernobyl disaster If Reactor #4 collapses, the gamma radiation would become immediately lethal to anyone within 300 feet

38 Works Cited Carr, Steven M. "The Millisievert and Milligray as Measures of Radiation Dose and Exposure." Memorial University, Web. 4 Sept Forms of Ionizing Radiation. Digital image. World Nuclear Association: Nuclear Basics. World Nuclear Association, Web. 30 Aug Harman, W. Dean. Personal interview. 30 August Health Physics Society. "Types of Radiation." Radiation Answers. Health Physics Society & Nuclear Energy Institute, Web. 03 Sept Lamarsh, John, Introduction to Nuclear Engineering, (Reading, MA: Addison-Wesley publishing Co., 1983), Moore, Karl. Infographic of the Electromagnetic Spectrum. Digital image.electromagnetic Radiation Protection. EMFsafespace, Web. 31 Aug "Nuclear Power in Japan." Nuclear Power in Japan. N.p., n.d. Web. 02 Sept

39 Works Cited Cont. "Radioactive Decay." Nondestructive Testing Resource Center. National Science Foundation, Web. 03 Sept Starr, By Steven. "About." Costs and Consequences of the Fukushima Daiichi Disaster. Physicians for Social Responsibility, n.d. Web. 05 Sept Tanabe, Fumiya. Analysis of Core Melt Accident in Fukushima Daiichi - Unit 1 Nuclear Reactor. Journal of Nuclear Science and Technology, vol. 48, no. 8, 5 Jan. 2012, pp Taylor & Francis Online, Tokyo Electric Power Co. Fukushima Daiichi Nuclear Power Station jnes.go.jp. Retrieved March 17, "What Is Radiation?" World Nuclear Association: Nuclear Basics. World Nuclear Association, Web. 30 Aug Chernobyl Accident World Nuclear Organization, June 2016,

40 Works Cited Cont. Mycio, Mary. How Many People Have Really Been Killed by Chernobyl? Slate, es_are_caused_by_low_level_radiation.html. Nuclear crises: How do Fukushima and Chernobyl compare? The Guardian, 12 Apr. 2011, TEPCO: Fukushima meltdown announcement made months late. CNN, 30 years since Chernobyl and 5 years since Fukushima What have we learnt? Read more at Cancer Research UK, scienceblog.cancerresearchuk.org/2016/04/26/30-years-since-chernobyl-and-5-years-since-fukushima-what-h ave-we-learnt/. Accessed 16 Apr