Godzilla, the Hills Have Eyes, and The Chernobyl Diaries: What are they doing out there?!

Transcription

1 Godzilla, the Hills Have Eyes, and The Chernobyl Diaries: What are they doing out there?! Presented by Audrey Garrett & J. Wayne Poole of Idaho National Laboratory

2 Video 2

3 FEAR 3

4 Why are we here? We want to dispel fears, and help you understand the dangers, and how we control them. We believe the answers to the nations energy needs can be met with nuclear power solutions. It s what we do at Idaho National Laboratory everyday, search today for the answers to the most challenging questions of tomorrow. We hope we can build a brighter, cleaner, safer, and more efficient future for our nation. 4

5 Objectives Discuss basic nuclear physics, to include atomic structure and forces within an atom. Educate on Nuclear Criticality Safety, its basic concepts and safety controls in the Nuclear Industry Educate on Radiation Safety, it s basic concepts and how we protect our radiation workers in the field. Educate on Nuclear Safety, requirements and implementation. Explain sustainability of nuclear energy. Explain the applications and efficiency of nuclear energy vs other fuel sources. 5

6 Basic Structure of the Atom 6

7 Basic Atomic Structure Atom: the basic unit of a chemical element. 3 Basic Parts of an Atom: Electrons Protons Neutrons 7

8 Atomic Particles 8

9 Forces within an Atom 9

10 Forces within an Atom There are four forces (Electromagnetic, Strong, Weak, and Gravity) that are responsible for the behavior of the particles and thus keep the atom together. 10

11 Basic Nuclear Physics: Quick Review An atom contains three basic subatomic particles: protons, neutrons, and electrons. There are four forces within an atom that effect its behavior: The strong force, weak force, electromagnetic force and the gravitational force. The strong force is by far the strongest in the nuclei. 11

12 Nuclear Power Generation through Fission When the nucleus of an atom absorbs a neutron, several things may happen. Nothing, emission of energy, or nuclear fission. When an atom fissions, the nucleus splits, releasing energy in different forms. In a nuclear power reactor, we introduce a neutron source into a system that contains fissionable materials, causing them to release energy. This energy is captured in the form of heat, and used to generate steam and electricity. This does create hazards, which are mitigated through the several Nuclear Industry Safety programs. The main programs include: Criticality Safety Radiation Safety Nuclear Safety 12

13 Criticality Safety Criticality: A self sustained nuclear chain reaction. Effective Multiplication Factor (keff): The amount of neutrons generated by nuclear fissions during the current generation compared to the amount created last generation. keff = # neutrons current generation / # neutrons past generation When keff<1, the system is subcritical. This is desired in most research applications. When keff=1, the system is critical. This is desired in nuclear reactors for power generation. When keff>1, the system is supercritical. Subcritical Critical Supercritical 13

14 Fission Chain Reaction Demonstration 14

15 Criticality Safety MERMAIDS Mass Enrichment Reflection Moderation Absorption Interaction Density Shape Sandia Pulse Reactor (SPR) Facility 15

16 Mass How much of the fissionable material do you have? Many non-nuclear power applications simply limit the controlled area to less mass than what could cause a criticality. The mass limit depends on the type and form of the isotope, and can range from 500 grams to many kilograms. Example: Fuel Bottle Design 16

17 Enrichment Different isotopes occur in nature. When working with fissionable materials, we dilute or concentrate the fissile isotopes for nuclear applications. Example: Uranium that is found in nature consists mostly U-238. This isotope is relatively stable. The natural uranium also contains small amounts of U-235. U-235 is the fissionable component that is the material chiefly used in nuclear reactors. The uranium is processed to increase the amount of U-235. This process increases the concentration (enrichment) to increase the probability for fission. The higher the enrichment, the less material you need to achieve criticality. Oklo, natural reactor in Africa 17

18 Reflection When nuclear material fissions, it releases energy particles to include more neutrons. Some of these neutrons will escape the fissionable material mass. Certain items act as good reflectors, meaning the neutron that has escaped the mass will bounce off of the material and reflect back into the fissionable material mass. These items include: Concrete, steel, water, people, and many more. Administrative controls and physical barriers are used to control reflection.. 18

19 Moderation When a neutron is released from a nucleus by the fission process, it has a lot of energy and therefore is called a fast neutron. These Neutrons are not likely to interact with other nuclei Neutrons slow down over (lose energy) due to collisions with other nuclei. Material having nuclei with low masses are more effective at slowing down neutrons. These materials are called moderators. Good moderators include: water, oil, polyethylene (basically any hydrogenous material) and graphite. Some applications require more or less moderation depending on what the desired outcome. Engineering barriers and administrative controls are used to control moderation. 19

20 Absorption Certain materials contain nuclei that have a mass energy balance that allow them to absorb a neutron(s) with little or no effect on the atom. They absorb neutrons and do not fission or emit vast amounts of energy. This takes neutrons out of the system, thus reducing k eff and the chances of achieving criticality. These materials include Boron, Cadmium, Halfnium, and more. Reactor control rods, storage racks, process vessels, etc may contain these materials for absorption. Raschig rings used in process vessels. 20

21 Interaction Fissionable materials may interact with each other. Interaction occurs to nuclear materials within storage arrays. Neutrons will only travel so far outside of the nuclear material. By controlling the spacing of the nuclear material within containers or storage racks, we can prevent neutron interaction of fissionable materials thus reducing the likelihood of criticality. Example: Fuel pin spacing wire, fuel storage racks 21

22 Density Density can be defined as the degree of compactness of a substance. The more compact a materials is, the more nuclei the material will have per unit volume. This increases the chance a free neutron will have to be thermalized and absorbed by within a nucleus. In turn, this increases the number of possible fissions, therefore increasing k eff. The more dense the material is, the more likely fission will occur within the fissionable material and the more likely you are to achieve criticality. 22

23 Shape The shape of the nuclear material mass will change the distance a free neutron must travel the escape the nuclear material. The longer the distance is (or the smaller the surface area to volume ratio), the more chances a neutron will have to be absorbed by a nucleus and cause a fission. Thus, the shape effects the probability a neutron can escape from the system thus affecting k eff. Criticality safety engineers use tools (like Monte Carlo code software) to aid in criticality parameters calculations. Example: fuel pin design 23

24 Criticality Safety Review MERMAIDS examines different aspects of criticality control. Includes mass, enrichment, reflection, moderation, absorption, interaction, density and shape. Every situation that involves nuclear material must have a criticality safety evaluation conducted. We have engineering tools to aid in these safety evaluations. We have software programs the aid us in modeling different situations. Double contingency is employed in all criticality safety controls. 24

25 Radiation Safety- Radioactivity Radioactivity: the process of unstable atoms becoming stable by releasing (emitted or radiating) energy. Every person everywhere is exposed to radiation every moment of their lives. Types of radiation include ionizing (has enough energy to remove electrons from an atom, thus charging the atom) and nonionizing(excites an electron but lacks the energy to remove it from an atom). Measured in millirem (mrem) There are four types of ionizing radiation we study in the nuclear field: Beta Particles- small mass, -1 charge. Neutron Particles- one free neutron, no charge. Alpha Particles- large mass, made of two protons and two neutrons. Gamma Rays- no mass, no charge, electromagnetic energy. (X-rays are also a form of radiation, very similar to gamma rays) 25

26 Sources of Ionizing Radiation Natural: The food we eat (bananas, potatoes, many more) Terrestrial (ground mineral sources) Cosmic (radiation entering our atmosphere from sources in space) Man-made: Industrial Medical Consumer products Average annual dose from natural and man made sources is 620 mrem per year. Volunteer? 26

27 Effects of Radiation on the Human Body Possible effects of radiation on cells range from no damage, damage and repair, damage repair and operate abnormally, or the cells die. Cells that are actively dividing are more susceptible to damage from radiation. These include blood forming cells, cells in the intestinal tract, and hair follicles Cells that are specialized and divide less actively are more radioresistant. These include brain, nerve and muscle cells. Doses of radiation can be acute (over a short period of time) or chronic (over a long period of time) Immediate Acute Biological Effects Dose (rem) Effect 0-25 Non detectable through symptoms or routine blood tests Changes in blood Nausea, loss of appetite Diarrhea, hemorrhage, and possible death 27

28 Radiation Shielding Different particles are shielded by different materials due to their relative size and energy. Alpha particles: Travel a short range, only 1-2 inches in air. They have a large mass and charge, but are shielded by materials as thin as paper or the outer layer of the skin. They are internally hazardous, due to the fact they have a large charge and are bone seeking particles. Beta particles: Also short range, travel about 20 feet in air. They have a small mass and charge and are shielded easily by plastic, aluminum, and glass. The primary hazard of beta particles is internal and to soft body tissues, like the eyes and skin. Neutron Particles: Travel very far in air, several 100 feet. They are harder to shield due to no charge and high penetration factors. However they are shielded well with materials like concrete, water, plastic and other hydrogenous materials. They are hazardous to the entire body. Gamma Rays: have no mass no charge, are very similar to x-rays. They are long range, greater than 100 feet in air. These rays can be shielded by lead, steel and concrete. (Similar to gamma rays) 28

29 Radiation Shielding Demonstration 29

30 Radiation Dose Limits Radiation dose is controlled by time, distance, and shielding. DOE limits the dose received by each radiation worker to 5 Rem/year. Remember, this is far less than the 25 acute dose range where biological changes may be detectable. Facility administrative control limits are far lower than the DOE limit, with most workers having a limit of mrem. Areas that have doses greater than background are required to be posted and have barriers according to the level of radiation. Each job has a work permit that allows a small radiation dose and stay time. Dose is monitored using dosimetry equipment. (Example) The expectation is that all radiation doses from radiation work will be ALARA, as low as reasonably achievable. 30

31 Contamination While radiation is energy, contamination is actual material that is uncontained and in an unwanted location. It can be fixed, removable, or airborne. Radiation workers can be subject to contamination by several methods: Inhalation, ingestion, and incision. Areas with any contamination are required to be blocked and marked with a contamination area boundary. Contamination control is achieved by the following methods: Preventative controls Administrative controls Good Rad work practices Contamination control procedures Personal Protective Equipment (PPE) 31

32 Review of Radiation Safety There are many sources of radiation all around us, both natural and man-made. The ionizing radiation particles include alpha, beta, and neutron particles as well as gamma rays. All of these particles can be shielded and controlled by different materials. Unique hazards associated with radiological work include radiation and contamination. Radiation is controlled by time, distance and shielding. Dose is federally limited and is monitored by dosimetry equipment. Contamination is controlled by good housekeeping, radiation worker practices, radiation boundaries, and PPE. 32

33 Nuclear Safety Safety Basis: DOE approved documented safety analyses (DSA s) and hazard controls that provide reasonable assurance that a DOE nuclear facility can be operated safety in a manner that adequately protects workers, the public, and the environment. Safety Basis is mandated and overseen by DOE through federal regulation and continuous oversight. Items included in the safety basis may include: Documented safety analysis (DSA) Technical Safety Requirements (TSR) Un-reviewed Safety Question (USQ) Hazard Assessment Documents (HAD) Basis for Interim Operations (BIO) Evaluations of the safety situation (ESS) DOE Safety Evaluation Reports (SER) 33

34 Hazard and Accident Analysis 10 CFR 830 requires nuclear facilities to provide systematic identification of both natural and man-made hazards associated with the facility. All possible normal, abnormal, and accident conditions/scenarios must be identified that could contribute to the release of hazardous materials. Not only must we identify the possible scenarios, we must also document the likelihood, potential consequences, preventative and mitigative features, identify which components are safety significant components, and much more. We then design based on the worst case scenarios, as well as develop controls and facility response procedures for all possible credible adverse scenarios. 34

35 Safety Structures, Systems, and Components DOE also requires that facilities identify and provide details on which pieces of equipment are necessary for the facility to protect the public. These are called Safety Class Components (SCC s). DOE also requires that facilities identify and provide details on which pieces of equipment are necessary for the facility to contribute to worker safety. These are called defense in depth (DID). We then develop Technical Safety Requirements (TSR). These are the limits, controls and related actions that establish the specific parameters and requisite actions for the safe operation of a nuclear facility. 35

36 Safety Analysis Reports These reports document nearly all nuclear aspects of a facility. They define everything from the approved construction materials for the structure, the exact material isotopes allowed in the facility, the amount of material allowed, the approved equipment and details of the approved processes. 36

37 Un-reviewed Safety Question Process Any significant work to be performed must be reviewed by someone trained, experienced, and knowledgeable in all facility safety basis requirements. The work must be reviewed to ensure that it is covered in the safety basis that has been approved by DOE. If it has not, it must be prior to performing the work. This work can be as minor as hanging a bulletin on a bulkhead, all the way to introduction of new fuel types into a facility. USQ approval requires documented proof, peer review, and management review. 37

38 Nuclear Facility Categorization Nuclear facilities are categorized in two different fashions: Hazard Category and Safeguards Categories. Each nuclear facility must establish both. Hazard Category: The facility hazard category is based upon the possible consequences of the worst accident scenario. Guidance is offered on categorization based on threshold quantities of nuclear material and safety analysis reports. Safeguards Category: Safeguards are the security measures associated with the facility. It is based on the amount, type and form of the material, and the operations conducted in the facility. This categorization determines the security measures and pro-force requirements associated with the facility and it s operation. 38

39 It sounds like a lot of work, but most things that are worth it usually are. We certainly believe it is. And here is why 39

40 Benefits of Reactor Power Reactors provide reliable power. Supports the infrastructure and security of our country. Could aid in eradicating global poverty. Sources of fuel for nuclear power generation occur in nature. We are constantly developing ways to reduce the amount of fuel needed to generate power, we already have methods to re-use spent nuclear fuel, and already have methods to recycle spent nuclear fuel. Nuclear power provides vast amounts of energy from small amounts of fuel. 40

41 Stability of Nuclear Power Nuclear energy is a reliable energy source, providing ondemand baseload electricity 24/7. The average nuclear energy facility is on line 90 percent of the time, generating on-demand electricity around the clock. Nuclear power is not dependent on local resources. Once start up is complete, power generation seldom fluctuates. 41

42 America s population is becoming more and more dependent on operation of our electric grid, data centers, telecommunications networks, and other critical infrastructure. Attacks on the infrastructure by terrorism or other adversary are very real, as the grid can be damaged or destroyed in several different ways. The more reliable power sources we have feeding the grid, the more we can mitigate the effects of these attacks. National Grid Security 42

43 The Role of Nuclear Power in Eradicating Global Poverty Nuclear development programs like TerraPower aim to develop a sustainable and economic nuclear energy technology Bill Gates has long understood the essential role of reliable power in eradicating global poverty, and its evil stepchildren war and terrorism, and decided that nuclear was the best long-term solution for base load power. 43

44 The Role of Nuclear Power in Eradicating Global Poverty The world s population is expected to increase to nearly 9 billion by 2040 and net electricity generation is expected to increase 93 percent to support this growth. Current energy sources will be hard pressed to keep up with this demand without having major negative impacts on the environment. Nuclear energy is a proven source of reliable, base load power. Its economic performance and emissions-free benefits have significant advantages. Imagine a power that is not dependent on local resources, is reliable and sustainable. Imagine putting that kind of power in place with no clean water, no heat. Imagine! 44

45 What kind of Green are we talking about?.. OR.. 45

46 Sustainability of Nuclear Power Once the Uranium is spent in nuclear reactors, what is left is called depleted Uranium. Depleted Uranium can be recycled and used as a fuel source in newer generations of reactors (TerraPower Traveling Wave Reactors). Spent Sodium reactor fuel can also be re-processed through electrolysis, melting, and recasting. The end result, a fuel pin ready for production. The process of generating energy in nuclear power plants emits no greenhouse gasses. The only emissions associated are due to mining and transportation. 46

47 Good Things Come in Small Packages, Small Packages: Like Fuel! Nuclear energy facilities are able to produce electricity with low cost and stable prices using enriched uranium for fuel. One uranium fuel pellet about the size of the tip of a pencil eraser produces the same energy as 17,000 cubic feet of natural gas, 1,780 pounds of coal or 149 gallons of oil. 47

48 Nuclear Energy Efficiency 48

49 Review of Benefits of Nuclear Power Nuclear fuel is stable and nondependent Increases security of our critical infrastructure Has the potential to provide efficient low cost energy solutions to any location, thus the potential to improve quality of life to many peoples around the world. No greenhouse gases are emitted when processing nuclear fuel to create energy. Nuclear fuel is re-usable and recyclable. A little goes a long way. 49

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51 References

52 References (Cont d) Radiological Worker I and Radiological Worker II, INL70, R06, Idaho National Laboratory. Typical-radiation-shielding-materials Energy/Electricity-Supply