Commercial Nuclear Power Fact, Fiction and Perception First Things First Forget everything that youve learned about nuclear power from this guy About Me: Larry Reynolds 30 Years Experience in Nuclear Power I entered into the nuclear power field when I enlisted in the US Navy.
I served aboard the USS Pogy (SSN 647) as a Nuclear Mechanic and Reactor Plant Operations Supervisor. I came to Illinois to work at the Braidwood Nuclear Station in Southwest Will County.
I first worked at Braidwood writing instructions for Mechanical Maintenance tasks. I later provided oversight of their Preventive Maintenance Program. I then worked as a Work Week Manager to provide overall scheduling and coordination of all work in the plant for a given week (5 week rotation). I retired from Exelon (Braidwood Station) last August. I currently work at HydroAire in Chicago at their Nuclear Pumps Division. Part 1:The Theory The Theory? - How Does it Work?
At its simplest, nuclear power plants use the heat created by the nuclear fission of U235 (Uranium) to make steam.The steam is used to spin a turbine which is coupled to a generator.This produces electricity. The Theory - How Does it Work? Definitions: Core: The area of the reactor that houses the fuelassemblies Fission: The process of splitting atoms (usually U235) Fission Product: smaller molecules created by thefission of Uranium these are often unstable(radioactive) Fusion: The process of combining atoms (usually H2) Free Neutron: A neutron that is not part of amolecule its by itself Fast Neutron: A free neutron that has most of theoriginal energy that it gained from the fissionprocess Thermal (or slow) Neutron:A free neutron that haslost most of its energy to the moderator Definitions: Poison: A material placed in a reactor to absorbneutrons so that the fission reaction can becontrolled or stopped (Usually Boron or Hafnium) Control Rod: A rod that is made from a Reactor Poisonand is located in the middle of most fuel bundles.They are raised or lowered to control reactor power.They can also be rapidly inserted into the fuelbundle during an automatic shutdown of the reactor. SCRAM: Slang for an automatic or manual shut down ofthe reactor.This is performed by causing a rapidinsertion of control rods.The term originated atthe first test reactor at Fermi Lab in Chicago(Safety Control Rod Ax Man) Moderator: A substance with a low molecular weightused to slow neutrons (common moderators are water,helium and graphite) The Theory So what heats up the water? The Fission Process for U235 Keff= number of neutrons in one generation number of neutrons in preceding generationkeff =LfpLthfn keff= the effective multiplication factor of neutrons in the core If keff is greater than 1, the chain reaction issupercritical,and the neutron population willgrow exponentially.If keff is less than 1, the chain reaction issubcritical,and the neutron population willexponentially decay.If keff = 1, the chain reaction iscriticaland the neutron population will remain constant. = Fast fission factor total number of fission neutrons number of fission neutrons from just thermal fission Lf= Fast neutron non-leakage probability The probability that afast neutronwill not leak out of the system p = Resonance escape probability Fraction of fission neutrons that manage to slow down from fission tothermal energies without being absorbed Lth= Thermal neutron non-leakage probability The probability that athermal neutronwill not leak out of the core f = Thermal utilization factor Probability that a neutron that gets absorbed does so in the fuel material n= Thermal Fission FactorThe number of fissionneutronsproduced per absorption in the fuel WHAT THE WHO!!!???? A reactor that is critical simply meansthat it is neither gaining or losingfree neutrons in the core.In otherwords, the power level is stable neither increasing or decreasing. Part 2:The Perception What does a Nuclear Plant look like?
The reality is that there is a lot of misinformation about Nuclear Power. What does a Nuclear Plant look like? Like this, Right? This is actually a Coal Burning Power Plant
These large cooling towers are used in many different types of power plants. Perception Three Mile Island was the worst incident at a commercial US plant, yet no radiation was released. Public outcry after this incident was responsible for many utilities abandoning plans for construction of new plants.Some of these plants were already in the process of being constructed. The Chernobyl accident released large amountsof radiation in Russia and caused manydeaths.Many people assume that an accidentlike Chernobyl could happen here.USRegulations prohibit a design like that usedat Chernobyl and also prohibit the type oftesting that was being performed that led tothe accident. Part 3: Practical Application Application Nuclear Power is unique:
People tend to be frightened of what they dont understand, andnuclear power is complicated. The US Government and US Nuclear Plant Licensees (owners) bothhave roles in the safe operation of Nuclear Power Plants in theUS. The NRC must approve the design of any nuclear plant prior tostart of construction. On the left ground preparation and pouring of the foundation for nuclear plant containment buildings On the Right lowering a turbine rotor assembly into its lower casing. Application Because of the severe consequences of a nuclear accident, the nuclear industry is highly regulated. Prior to start of operation, each plant must receivea license to operate from the NRC that has the forceof law and covers design, maintenance, testing andoperations of the plant. Picture of a nuclear plant control room Application Because of the severe consequences of a nuclear accident, the nuclear industry is highly regulated. Nuclear workers have FBI background checks and drug screening prior to being allowed unescorted access to a nuclear plant.Random checks are required as long as access is allowed. Every year each nuclear plant employee must complete training on emergency procedures, security protocols, radiation safety and other topics important to nuclear safety. The NRC requires positive ID of each employee prior to entryinto the plant (security badges and hand scanners). All employees and packages are screened prior to entry inthe plant (similar to airport screening). This includes all staff cafeteria workers, janitors, etc One of my responsibilities was to be a communicator to the State of Illinois Application Because of the severe consequences of a nuclear accident, the nuclear industry is highly regulated. Drills that simulate various emergency scenarios areheld on a regular basis to test the communication,response and coordination between each Nuclear Plant,Response Centers, State and Local Governments. Picture is of a Technical Support Center which is activated during an incident to remove communications burden from the control room One of my responsibilities was to be a communicator to the State of Illinois Application Nuclear industry regulations (continued):
Fences, key-carded doors and an armed security force areall used to enforce security.Each plant has a uniqueSecurity Plan based on its location and plantgeography.Each plan must be approved by the NRC andincludes the design of the permanent structures as wellas number of guards on staff, the type of weapons on- site, etc. Periodic drills are performed to test plant securitystaff response to a simulated attack.A ninja forcesimulates an attempt to enter the plant and damage thereactor with both sides using laser tag rifles. Application Nuclear industry regulations (continued):
Almost every activity at a nuclear plant is performed using a procedure or set of work instructions that is reviewed against the plants operating license prior to approval to ensure that all regulations are met. Every component (and sub-component) that isimportant to nuclear safety has beenevaluated in detail to ensure that it canbe relied upon to perform as required. Thisincludes detailed analysis of breakingstrength, resistance to corrosion, andother pertinent material attributes. Allparts used must have traceability anddocumentation of all phases of manufactureand testing. On March 5, 2002, maintenance workers discovered that corrosion had eaten a football-sized hole into the reactor vessel head of the DavisBesse plant. Although the corrosion did not lead to an accident, this was considered to be a serious nuclear safety incident. The NRC kept DavisBesse shut down for 2 years, so that FirstEnergy was able to perform all the necessary maintenance. The NRC imposed its largest fine evermore than $5 millionagainst FirstEnergy. The company paid an additional $28 million to the U.S. Department of Justice. The USS Thresher (SSN-593) was the lead boat of her class of nuclear-powered attack submarines in the United States Navy. Her loss at sea in the North Atlantic during deep-diving tests approximately 220 miles east of Boston, Massachusetts, on 10 April 1963 was a watershed event for the U.S. Navy, leading to the implementation of a rigorous submarine safety program known as SUBSAFE. This was the first U.S. nuclear submarine lost at sea (out of two).On 9 April 1963 Thresher got underway from Portsmouth at 8 am and rendezvoused with the submarine rescue ship Skylark at 11 am to begin its initial post-overhaul dive trials. Thresher slowly dived as it traveled in circles under Skylark to remain within communications distance pausing every additional 100 feet of depth to check the integrity of all systems. As Thresher neared her test depth, Skylark received garbled communications over underwater telephone indicating "... minor difficulties, have positive up-angle, attempting to blow", and then a final even more garbled message that included the number "900".When Skylark received no further communication, surface observers gradually realized Thresher had sunk. A Court of Inquiry concluded that Thresher had probably suffered the failure of a salt-water piping system joint which relied heavily on silver brazing instead of welding; earlier tests using ultrasound equipment found potential problems with about 14% of the tested brazed joints, most of which were determined not to pose a risk significant enough to require a repair. High-pressure water spraying from a broken pipe joint may have shorted out one of the many electrical panels, causing a shutdown ("scram") of the reactor, with a subsequent loss of propulsion. Application The USS Thresher (SSN-593) was the lead boat of her class of nuclear-powered attack submarines in the United States Navy. Her loss at sea in the North Atlantic during deep-diving tests approximately 220 miles east of Boston, Massachusetts, on 10 April 1963 was a watershed event for the U.S. Navy, leading to the implementation of a rigorous submarine safety program known as SUBSAFE. This was the first U.S. nuclear submarine lost at sea (out of two).On 9 April 1963 Thresher got underway from Portsmouth at 8 am and rendezvoused with the submarine rescue ship Skylark at 11 am to begin its initial post-overhaul dive trials. Thresher slowly dived as it traveled in circles under Skylark to remain within communications distance pausing every additional 100 feet of depth to check the integrity of all systems. As Thresher neared her test depth, Skylark received garbled communications over underwater telephone indicating "... minor difficulties, have positive up-angle, attempting to blow", and then a final even more garbled message that included the number "900".When Skylark received no further communication, surface observers gradually realized Thresher had sunk. A Court of Inquiry concluded that Thresher had probably suffered the failure of a salt-water piping system joint which relied heavily on silver brazing instead of welding; earlier tests using ultrasound equipment found potential problems with about 14% of the tested brazed joints, most of which were determined not to pose a risk significant enough to require a repair. High-pressure water spraying from a broken pipe joint may have shorted out one of the many electrical panels, causing a shutdown ("scram") of the reactor, with a subsequent loss of propulsion. USS Thresher: Poor materials and construction caused sinking of this submarine.As a result, the US Navy implemented SUBSAFE program to ensure quality of materials used in submarines. This method was also adopted at nuclear plants shortly thereafter. Application In addition to careful selection, testing and documentation of replacement parts, all maintenance must be planned and scheduled to ensure that: Removal of equipment from service will not violate any part of the operating license due to loss of redundancy Procedures and work instructions are used to ensure work is performed correctly Radiation and contamination exposure are minimized (Time, Distance, Shielding) Equipment is scheduled to be operated (or exercised) at periodic intervals to prove to the NRC that it could operate as designed in an emergency. Application As a result of all of these processes and regulations, the majority of workers at a nuclear plant spend a great deal of their time performing engineering analysis, work planning, scheduling or documentation tasks. Most nuclear workers receive very little radiation.An airline pilot receives more radiation in a year than most nuclear plant workers. Major repair work, and all repair work inside of the containment building is performed during a refueling outage.This is when the reactor is shut down to allow for replacement of fuel bundles.This is also a key to lowering radiation dose rates to workers performing maintenance. On March 5, 2002, maintenance workers discovered that corrosion had eaten a football-sized hole into the reactor vessel head of the DavisBesse plant. Although the corrosion did not lead to an accident, this was considered to be a serious nuclear safety incident. The NRC kept DavisBesse shut down for 2 years, so that FirstEnergy was able to perform all the necessary maintenance. The NRC imposed its largest fine evermore than $5 millionagainst FirstEnergy. The company paid an additional $28 million to the U.S. Department of Justice. The USS Thresher (SSN-593) was the lead boat of her class of nuclear-powered attack submarines in the United States Navy. Her loss at sea in the North Atlantic during deep-diving tests approximately 220 miles east of Boston, Massachusetts, on 10 April 1963 was a watershed event for the U.S. Navy, leading to the implementation of a rigorous submarine safety program known as SUBSAFE. This was the first U.S. nuclear submarine lost at sea (out of two).On 9 April 1963 Thresher got underway from Portsmouth at 8 am and rendezvoused with the submarine rescue ship Skylark at 11 am to begin its initial post-overhaul dive trials. Thresher slowly dived as it traveled in circles under Skylark to remain within communications distance pausing every additional 100 feet of depth to check the integrity of all systems. As Thresher neared her test depth, Skylark received garbled communications over underwater telephone indicating "... minor difficulties, have positive up-angle, attempting to blow", and then a final even more garbled message that included the number "900".When Skylark received no further communication, surface observers gradually realized Thresher had sunk. A Court of Inquiry concluded that Thresher had probably suffered the failure of a salt-water piping system joint which relied heavily on silver brazing instead of welding; earlier tests using ultrasound equipment found potential problems with about 14% of the tested brazed joints, most of which were determined not to pose a risk significant enough to require a repair. High-pressure water spraying from a broken pipe joint may have shorted out one of the many electrical panels, causing a shutdown ("scram") of the reactor, with a subsequent loss of propulsion. Application INPO (Institute for Nuclear Power Operations) was formed shortly after the nuclear incident at Three Mile Island in December 1979. INPO Mission to promote the highest levels of safety and reliability to promote excellence in the operation of commercial nuclear power plants. INPO conducts evaluations of Plants to ensure that they are operated in a safe and reliable manner.These evaluations also establish and communicate best practices across the nation (and world - by participation in WANO). Provides an independent assessment of the quality of operations at a power plant. INPO allows the nuclear industry to self-police itself. Part 4:Comparisons Comparisons: Nuclear Larger Nuclear plants have capacities of 1200Mw and can generate an average of 20,000,000 MwHr in a year (2 unit site). Power plants (not just nuclear) can kill fish in large numbers due to the heating of river, lake and sea water. Comparisons: Nuclear Nuclear plants generate low level waste as well as spent fuel.The government has agreed to take on the responsibility for disposal of spent nuclear fuel. Cherenkov radiation, also known as VavilovCherenkov radiation, is electromagnetic radiation emitted when a charged particle (such as an electron) passes through a dielectric medium at a speed greater than the phase velocity of light in that medium. The characteristic blue glow of an underwater nuclear reactor is due to Cherenkov radiation. It is named after Soviet scientist Pavel Alekseyevich Cherenkov, the 1958 Nobel Prize winner who was the first to detect it experimentally. Comparisons: A single uranium fuel pellet the size of a pencil eraser contains the same amount of energy as 17,000 cubic feet of natural gas, 1,780 pounds of coal or 149 gallons of oil. Comparisons: Nuclear energy data
A typical nuclear power plant generates 20tons of used nuclear fuel in a year. Thisused fuel is stored on site in spent fuelpools or NRC approved storage units. About 95 % of LLRW decays to backgroundlevels within 100 years or less. Low-level radioactive waste is stored inspecial disposal facilities across thenation.These disposal facilities alsostore Low-level radioactive waste frommedical and industrial sources. Comparisons: Wind Most wind energy comes from turbines that can be as tall as a 20-story building and have three 200-foot-long (60-meter-long) blades. The largest wind turbines being manufactured today can produce 2 Mw each with adequate wind. Wind turbines only work when the wind is blowing (Duh!). This would mean that to equal a nuclear power plant, a wind farm would need 600 wind turbines. Typical spacing is 7X the rotor diameter or every 1400 feet. Placed in a single row, this would be 840,000 feet long(or 160 miles long or 180 square miles if placed in a grid). DOE documents estimate bird kills from wind turbines at about 1 bird per Mw per year (or 1200 birds per year in the above example).They also estimate that in areas with bats, the bat kill would be 30 bats per Mw per year (36,000 bats per year in the above example). Comparisons: Solar Fossil (Oil, Natural Gas and Coal) Conservation
The amount of electricity produced by a multi-reactor nuclear power plant would require more than 60 square miles of photovoltaic panels Fossil (Oil, Natural Gas and Coal) Carbon Dioxide emissions (acid rain) Like nuclear plants, these plants can also result in fish kills Conservation Use less electricity Buy products that have a minimal of processing (extensive processing usually means extensive electrical usage) FAQs: FAQs: What is used nuclear fuel? How is used nuclear fuel stored?
Used uranium fuel assemblies from commercial reactors still have 90 percent of the original potential energy.Theyare currently stored at nuclear energy facilities where they are used. How is used nuclear fuel stored? Most plants store used fuel in steel-lined, concrete vaults filled with water, which acts as a natural barrier for radiation from the used fuel. The water also keeps the fuel cool while it becomes less radioactive. The water itself does not leave the used fuel pool, rather is constantly circulated to maintain a suitable temperature. After at least five years of storage in the used fuelpool, the rods can be moved into large, heavilyshielded concrete and steel storage containers, whosedesigns must be approved by the Nuclear RegulatoryCommission. There it awaits removal by the U.S.Department of Energy to a disposal facility. FAQs: What is low-level radioactive waste?
Low-level radioactive waste is a byproduct of the uses of radioactive materials.This includes waste from electricity generation, medical diagnosis and treatment, biomedical and pharmaceutical research and manufacturing. It is solid material that is transported under strict regulations established by the U.S. Department of Transportation and the Nuclear Regulatory Commission. Low-level radioactive waste usually consists of items such as gloves and other protective clothing, glass and plastic laboratory supplies, machine parts and tools, and disposable medical items that have come in contact with radioactive materials. FAQs: What is radiation?
The radiation one associates with a nuclear power plant are particles, such as alpha rays and gamma rays, emitted as a result of the fission process. Do nuclear power plants release radioactive material? Yes, but in small levels that are regulated by the federal government. Nuclear power plants produce radioactive gases and liquid wastes during normal operation. A plant has tanks designed to store gas and liquid radioactive materials that are generated during normal operation. The radioactive material is held for a period of time to allow for the radioactivity level to decrease before being treated and/or released in a planned, monitored way. This keeps the amount of radioactive material in releases low and well within federal limits. FAQs: How did the 2011 nuclear accident in Japan affect the nuclear energy industry? In the United States, the nuclear energy industry and the NRC immediately took steps to make facilities even safer than before the accident. Most other countries took a similar approach to the United States and kept their facilities operating. Germany and Switzerland are phasing out their nuclear energy facilities. Japan shut down its plants, but has restarted one and may restart others after they make safety upgrades. The industry quickly implemented a safety enhancement strategy to ensure that plants have the additional equipment needed to respond to extreme natural events such as the tsunami in Japan. The industry initiative will provide additional sources of water and electric power to keep the reactor and used fuel pool cool if electricity from the grid is unavailable, as it was in Japan. Additional generators, batteries, water pumps and other emergency equipment have been purchased at each site. In addition, regional response centers in Tennessee and Arizona will maintain more emergency equipment that can be dispatched quickly to any facility that needs it. QUESTIONS ??? Links: http://www.nei.org/Knowledge-Center/Nuclear-Statistics