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Atomic and Nuclear Phenomena 

December 16, 2023

The history of nuclear energy is one that intertwines scientific discovery, technological ingenuity, geopolitical dynamics, and the controversial quest for a powerful energy source. Nuclear materials are part of the earth's crust and have been for millions of years, yet the ability to safely harness nuclear energy for modern power generation is more recent than one might think. Beginning with early 20th-century breakthroughs in atom structure and continuing to present-day debates surrounding its implementation, nuclear energy has been a subject of the world's fascination for over a century.

The roots of nuclear energy can be traced back to the late 19th and early 20th centuries when pioneering physicists began unraveling the mysteries of atomic structure. By revealing that atoms could be split to release immense amounts of energy, the groundbreaking work of figures such as Marie Curie, Ernest Rutherford, and Niels Bohr helped lay the foundation for nuclear power. However, it wasn't until 1939 that nuclear fission, the process of splitting atoms to release energy, was experimentally demonstrated. 

The first controlled nuclear chain reaction occurred in Chicago during the wartime Manhattan Project 1942, a top-secret research and development endeavor that led to the creation of atomic weapons. Three years later, the first nuclear weapon was tested in New Mexico, and in 1948, atomic reactors were the first to generate electricity at a power plant in Idaho. While advancements in this time proved to bring significant technological breakthroughs, concerns surrounding the ethics of using atomic energy were also raised. Consequently, following the war, the focus shifted towards harnessing nuclear energy for peaceful purposes. 

Problem Statement:Describe and illustrate the process of nuclear fission in the context of its role in energy production. Students should use the description above and their knowledge of subatomic particles and forces to construct an illustration of and description of the process of nuclear fission. Chapter 17: Nuclear Energy from Energy 101: Energy Technology & Policy contains a detailed description of the nuclear fission process within the energy industry's broader context. Consider assigning a reading and allowing students to synthesize the information from that chapter into their illustrations and descriptions.The BBC has produced a more straightforward explanation of the particulars of the process of nuclear fission and fusion. This site contains illustrations of the process, which can be used as an example against which to evaluate students' work. 

Assessment Criteria:Students should clearly articulate that nuclear fission is the process of using a high-energy neutron to split the nucleus of an atom into smaller atoms which releases more high-energy subatomic particles, which in turn repeat the process. Excellent work will recognize the introduction of a neutron to the atomic nucleus as the creation of an unstable isotope, which immediately breaks down, releasing energy and subatomic particles. Applying this knowledge to the energy industry, students should identify the preferred stable isotope, uranium-235, and the unstable isotope created uranium-236. Excellent work will contextualize the process of fission as occurring within the nuclear reactor core, where high-energy neutrons released from the initial reaction interact with other uranium-235 atoms in a chain reaction. The reactor core also contains the facilities to absorb the energy released from the reaction into steam generation for a traditional steam turbine.

Nuclear energy promised a way to meet the increasing demands for electricity without relying on fossil fuels, reducing greenhouse gas emissions and mitigating environmental impacts.

Throughout the latter half of the 20th century, atomic energy experienced both periods of rapid expansion and periods of stagnation. In the 1950s and 1960s, the world witnessed the birth of the first commercial nuclear power plants, marking a new era for clean and abundant energy. 

The potential for nuclear energy to revolutionize the global energy landscape was met with enthusiasm, leading to the construction of nuclear power plants across the globe. However, catastrophic incidents such as the Chernobyl disaster in 1986 and the Fukushima disaster 2011 raised concerns about nuclear safety and led to public apprehension regarding its implementation.

However, despite the controversies, nuclear energy remains a crucial component of the energy mix in many countries, providing significant electricity generation and contributing to energy security. Developing advanced reactor designs, including thorium-based and small modular reactors, promises a safer and more sustainable nuclear future.

Currently, the most common fuel for nuclear reactors worldwide is uranium-235 (235U), an isotope of uranium. Other fuels, such as thorium, can also be used, but uranium has become the conventional source of most production for various historical, geopolitical, and technical reasons. The critical physical aspect of controlled fission is the chain reaction that begins when a neutron splits a uranium atom. Splitting the atom emits more neutrons, which then split other atoms. During fission, some mass is lost, converted into thermal energy, as described by E=mc2. That heat can be used to make steam to spin a turbine and generate electricity.

Problem Statement:
During the process of nuclear fission with the uranium-235 isotope, 0.1 percent of the uranium's mass is "lost."¹ We know based on the law of conservation of mass that matter can neither be created nor destroyed, so where did this mass go? Thanks to Einstein's special relativity and his famous formula, physics has an answer for the intrinsic relationship between mass and energy. The 0.1% of uranium is converted to energy according to the principles of E=mc2. In this second activity, reveal to students that physicists weighed all the daughter nuclei and free neutrons from the illustration they created in the first activity and reported that 0.1% of the initial mass was converted during the process of nuclear fission. Have them use Einstein's mass-energy equivalence to calculate how much energy was produced from the fission of 1 gram (g) of uranium-235. (This amount is arbitrary and should not be perceived as the actual amount of fuel used in controlled nuclear reactions.)0.1% of 1 g uranium is 0.001 g or 0.000001 kg or 1 x 10⁻⁶ kgJ = kg m² s⁻²E = energy measured in joules (J)
m = mass measured in kilograms (kg)
c = the speed of light in meters per second (3 x 108 m/s)
E = mc2
E = (1 x 10-6 kg) x (3 x 108 m/s)2
E = (1 x 10-6 kg) x 9 x 1016 m2/s2
E = 1 x 9 x 1010 kg;m2/s-2
E = 9 x 1010 J
Chapter 17: Energy Basics from Energy 101: Energy Technology & Policy provides an introduction to nuclear energy. The BBC Bitesize GCSE review pages provide a succinct explanation with illustrations of the process of fission and fusion. Chemistry Matters from Georgia Public Broadcasting features a lesson on nuclear fission and the different types of radiation. Although formally aligned with the Georgia Standards of Excellence, this material also addresses the TEKS listed on this page.
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