Wired for Success – Practice Makes Perfect at Oconee Nuclear Station
So, how do you train employees to work on equipment that is rarely taken out of service? How do you reduce the risk in what is inherently a risky task due to lag times between execution? You do exactly what the Instrumentation and Electrical (I&E) crew at Oconee have done. You build your own relay simulator to practice on.
In a nuclear energy facility, some components are rarely taken out of service due to their required safety functions in plant operation. It’s not uncommon for two years to go by before human hands manipulate the components, especially the electrical relay circuitry that controls many plant systems.
The brain-child of in-house technicians Lane Bryant and Barry Bishop, the relay simulator is approximately 6 feet tall and 3 feet wide, made of fiber board with several different electrical circuit relays mounted on the board. Upon first glance, it may not seem like much to look at. Plug up the power supply to the simulator, though, and it’s a whole different story. The relay circuit lights glow and are fully connected to other circuits installed on the board. In other words, this simulator mimics the live wiring and connections in the plant. The technicians who built the mock relay board didn’t stop at just building a replica, however. Drawings were created to document the configuration of the board and they are in the process of incorporating employee standards into the board’s configuration to use it as an official, documentable training device.
The Oconee I&E team created the relay simulator to reduce a number of risks in executing electrical relay work safely and error-free. Relay circuits are typically only available for planned maintenance when the unit is shutdown for a refueling outage. This creates quite a challenge when a relay technician enters the plant to work on a circuit that he’s only encountered twice in 10 years. The potential for human error and unintended consequences somewhere else in the plant are greatly amplified in that situation. This is where the relay simulator comes into play. The technician can use the relay simulator to safely practice the work he is preparing to execute in the plant. There is no risk of negatively impacting the plant while using the relay simulator and the technician can get familiar with the task in a safe environment. “I am very proud of what this team has accomplished on their own initiative. The fact that this team recognized the need for an instrument to help us reduce risk to the station is a great testament to the strong nuclear safety culture at Oconee,” says Jeremy Fisher, I&E manager.
Technicians have only begun to scratch the surface of how this relay simulator can be used. The benefits of the relay simulator extend beyond training for the I&E technicians. Other plant groups can use the simulator for problem solving in a safe environment, mitigating the risk of doing problem solving in the plant itself. The maintenance department can use the simulator for On The Job Training (OJT) of different electrical relay circuit scenarios with qualified I&E technicians, and for training and qualifying new I&E technicians.
The possibilities are endless when you stop to consider the interconnectedness of systems and components in a nuclear facility. For now, the I&E crew is focused on how the relay simulator can improve their task execution and reduce risk by training and reviewing process steps in a safe environment. The old saying is true, “if you build it, they will come,” and other groups from the site and the rest of Duke Energy’s nuclear fleet are on their way to see what this new tool is all about.
Oconee I&E Crew (pictured from left to right): Barry Bishop, Kyle Watkins, John Todd Lynch, Jerry Welborn, Lane Burgess
Not pictured: Andrew Powell, Shaun Thomas, Josh Ward, John Gillespie and Aaron Mize
Hundreds Learn at McGuire that Science is Cool
April was a busy month for McGuire Nuclear Station. Hundreds of students of all ages joined in a special celebration of the NC Science Festival at the EnergyExplorium, the energy education center for McGuire Nuclear Station, throughout the month.
The EnergyExplorium hosted several programs over the past few weeks to encourage the love of science in students. NC Science Festival activities at the EnergyExplorium included an energy efficiency homeschool day, a student art show reception and tailored school programs.
During the Science Explore Days for local schools, students received interactive presentations on nuclear energy and electricity, tested their knowledge in challenging Jeopardy games, used Geiger counters to detect radiation and explored the EnergyExplorium’s energy lab to discover energy in everyday items.
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Homeschoolers also celebrated science at the EnergyExplorium during the “Good to be Green” Energy Efficiency homeschoolers day. Homeschoolers learned about the importance of conserving energy and ways to be more energy efficient. A Duke Energy green jobs expert engaged the students in a discussion about job possibilities in the green field and talked about his recent trip to Antarctica. Additionally, homeschoolers got behind the wheel of a Duke Energy electric vehicle as they learned about green transportation options.
The celebration of the NC Science Festival was concluded with an open house for the EnergyExplorium’s science-themed student art show. A small reception was held for artists and their families. The majority of the art focuses on science and the environment. The art, which was submitted by over a dozen public and private schools, homeschooled students and community art groups, will be on display in the EnergyExplorium through mid-May.
McGuire Nuclear Station hosts many events throughout the year. For more information on programs and events at the EnergyExplorium, please visit our website: www.duke-energy.com/energyexplorium. Duke Energy is a proud sponsor of the NC Science Festival. To learn more about the NC Science Festival visit www.ncsciencefestival.org.
Pumped-Storage Hydroelectric Energy Fills the Gap
As midnight approaches and Carolinians retire for the evening, energy consumption trails off sharply across Duke Energy’s electric generating system. Out of sight and mind, the utility’s nuclear generating fleet operates at full power night and day, with fossil units added to the system as needed to ensure customers have an uninterrupted electricity supply.
Demand for electricity varies, with the highest or peak demand occurring in the morning or afternoon, and lowest demand at night and on weekends. Utilities operate large nuclear and fossil units around the clock as “baseload” generation to meet the majority of demand, adding or removing smaller generation units as consumption rises and falls.
Baseload units operate best at full capacity 24 hours a day, which can create a generation surplus on the system during low-demand periods (nights and weekends). For almost 40 years, Duke Energy has used pumped-storage hydroelectric technology to capture this surplus generation for use during heavy or peak demand and to help reduce customer energy bills.
Conventional hydroelectric stations use water from a river or lake to spin turbine generators to produce electricity primarily for peak demand periods. Duke Energy has used hydroelectric generation for more than 100 years.
Pumped-storage hydroelectric stations have the unique ability to operate in either a generation or pumping mode. In the generation mode, water held in an upper reservoir flows by gravity through a turbine generator producing electricity before flowing into a lower reservoir just like a conventional hydroelectric station.
During pumping operations, excess electricity available during low-demand periods is used to spin the turbine generator in reverse. Water from the lower reservoir is pumped back to the upper reservoir, allowing the water to be recycled or used over and over again to produce electricity.
Bound by the laws of physics, the pumping mode uses more electricity than can be produced during the generation phase. What makes pumped storage useful is the ability to take surplus electricity during low demand periods to pump water uphill, making it available for use during peak demand periods.
In addition to giving a utility the flexibility to meet customer demand as economically as possible, pumped storage can respond to increases in electricity demand or voltage fluctuations within minutes.
Designed to operate at full capacity, the availability of Duke Energy’s low-cost nuclear generation during nights and weekends make it an ideal source of electricity for pumping operations at Jocassee and Bad Creek. Located in the Keowee-Toxaway River Basin in South Carolina, these two stations represent one of the largest concentrations of pumped-storage generation in the country, with a combined maximum generating capacity in excess of 2,000 megawatts (MW), enough power for approximately 1.6 million homes.
When used in a well-planned generating scheme, pumped storage plays an important role and can be one of the most economical forms of generation available.
Decommissioning: A Safe and Systematic Process for Retiring Nuclear Plants
Yankee Rowe nuclear plant in Rowe, MA before decomissioning.
The Nuclear Regulatory Commission (NRC) typically grants a license to nuclear power plants for a period of 40 years.
Before the end of the original license period, the utility can seek to renew the operating license of the plant or cease operations and begin the decommissioning process. Decommissioning entails safely removing a plant from service and taking steps to reduce the level of radiation to one that permits termination of the NRC license so the land may be used for other things in the future.The NRC requires plants to finish the decommissioning process within 60 years of closing. Strict decommissioning requirements enforced by the NRC require utilities to cleanup radioactively contaminated plant systems and structures as well remove radioactive fuel. These requirements protect workers and the public during the entire decommissioning process as well as the public after the license is terminated.
How is decommissioning funded?
Yankee Rowe site after decommissioning.
Nuclear power plants are required by the NRC to put aside funds for their decommissioning during operations. Duke Energy began collecting funds in 1979 to cover the estimated decommissioning costs for its nuclear plants. Utilities across the country work with federal and state regulators to ensure enough money is set aside for this process. These funds are not under the direct control of the companies and cannot be used for purposes other than decommissioning. Although there are many factors affecting cost, plant decommissioning ranges from $300 to $400 million.
How is a nuclear power plant decommissioned?
To decommission a nuclear power plant, the radioactive material on the site must be reduced to levels which wouldpermit termination of the license. This involves removing the used fuel and cleaning up or dismantling contaminated materials. All radioactive materials generally have to be removed from the facility and shipped to a waste processing, storage or disposal facility.The Nuclear Regulatory Commission offers three pathways to decommissioning:
- Immediate Dismantlement – Parts of the reactor are removed or decontaminated soon after the plant closes. This process involves immediate clean up after the plant shuts down.
- Safe Storage – The nuclear plant is monitored and radiation is allowed to decay; afterward, it is taken down.
- Entombment – Radioactive components are sealed off in robust material such as steel and are monitored and maintained while allowing radiation to decay. According to the NRC, no “NRC-licensed facility has requested this option.”
Click on the map above for a list of sites undergoing decommissioning.
To learn more about decommissioning, click on the fact sheets below:
The Nuclear Renaissance Reaches Another Milestone
Construction is already underway at the future site of V.C. Summer's two new reactors.
Last month, the NIC reported a major milestone in the nuclear renaissance: The Nuclear Regulatory Commission’s license approval of two new reactors at the Vogtle plant.
Not too far behind, the V.C. Summer plant in South Carolina was recently granted its combined construction and operating license (COL) for a two-reactor expansion. South Carolina Electric & Gas (SCE&G) and Santee Cooper, a state-owned electric and water utility, have a contractual agreement with Shaw for the construction of the reactors.
The two new reactors, each with a capacity of 1,117 megawatts are expected to begin commercial operation in 2016 and 2019. V.C. Summer already has one unit in operation which generates roughly 1,000 megawatts. About 1,000 workers are engaged in early construction but nearly 3,500 workers will be employed during peak construction.
V.C. Summer and Vogtle’s approved COLs show acceptance of nuclear energy as a safe, reliable energy source for the future.
Further Reading:
Power Restored at Catawba Nuclear Station
On April 4 at 8:12 p.m., Catawba Nuclear Station lost offsite power and an unusual event was declared. Power has been restored to the station and the unusual event emergency classification was terminated at 1:37 a.m.
The station’s diesel generators operated as designed to provide power to essential plant equipment. An unusual event is the lowest of four emergency classifications. This condition posed no threat to public safety, but required certain emergency response functions to be in a heightened state of readiness.
Duke Energy’s emergency operations facilities were activated and station employees responded to the situation. Appropriate federal, state and local officials were also notified.
Although power has been restored to the station, the units are not currently generating electricity. An investigation is being conducted regarding the cause.
For more information, click here.
The Blue Ribbon Commission Makes Recommendation on Managing Used Fuel
Aerial view of Yucca Mountain located in Nevada.
The Blue Ribbon Commission (BRC) on America’s Nuclear Future released its final report to the U.S. Energy Secretary in January 2012, detailing recommendations for creating a safe, long-term solution for managing and disposing of the nation’s used nuclear fuel.The commission, co-chaired by former Congressman Lee H. Hamilton and former National Security Advisor Brent Scowcroft, was tasked by Department of Energy (DOE) Secretary Steven Chu with recommending alternative approaches to managing nuclear waste. The commission was formed at the request of President Obama two years ago, the same time government efforts to license a geologic repository at Yucca Mountain, Nevada were terminated.
Report Findings
At the direction of Secretary Chu, the BRC was largely silent on Yucca Mountain as a potential site for geologic disposal of used fuel and radioactive waste. Instead, its report suggested ways to move the process forward for selecting and managing a permanent repository. The eight key elements from the report included:
- A new, consent-based approach to siting future nuclear waste management facilities.
- A new organization dedicated solely to implementing the waste management program and empowered with the authority and resources to succeed.
- Access to the funds nuclear utility ratepayers are providing for the purpose of nuclear waste management.
- Prompt efforts to develop one or more geologic disposal facilities.
- Prompt efforts to develop one or more consolidated storage facilities.
- Prompt efforts to prepare for the eventual large-scale transport of used nuclear fuel and high-level waste to consolidated storage and disposal facilities when such facilities become available.
- Support for continued U.S. innovation in nuclear energy technology and for workforce development.
- Active U.S. leadership in international efforts to address safety, waste management, non-proliferation, and security concerns.
Current Methods of Storing Used Fuel
Commercial nuclear power plants were designed and built with storage pools to provide safe on-site storage of used fuel assemblies. Most plants were designed with limited storage pool capacity due to the expectation used fuel would be temporarily stored on site. Faced with the need for extended and possibly life of plant fuel storage, utilities have pursued various options for expanding on-site storage capacity. Dry storage was selected as the preferred long-term option for meeting continued used fuel storage requirements at most nuclear plants, including Oconee, McGuire and Catawba. To learn more about storing used nuclear fuel, click here.
Efforts to Manage Nuclear Waste
In 1982, Congress passed the Nuclear Waste Policy Act (NWPA) and required the DOE to build a repository to dispose nuclear waste. According to the NWPA, the DOE was required to take control of used nuclear fuel from commercial nuclear power plants, collect a fee from nuclear power providers (the Nuclear Waste Fund) and transport the waste to a permanent geologic repository or an interim storage facility before permanent disposal.
Nuclear Waste Fund Fast Facts:
- The Nuclear Waste Fund has thus far collected roughly $25 billion.
- Duke Energy began paying into the fund in July 1983, and has continued to pay into the fund to the present time.
- The payment for the waste fund is based upon generation from the nuclear units in the Duke fleet. The payment is $0.001 per kilowatt hour produced. For the average customer, the cost would be approximately $5.85 per year.
- Customers of electricity generated at the Oconee, McGuire and Catawba Nuclear Stations have paid approximately $1.45 billion into the fund.
To read the Commission’s full report, click here.
Pressurized Water Reactors (PWR) and Boiling Water Reactors (BWR)
Power Plant Reactors
With the exception of solar, wind, and hydroelectric plants, most power plants are steam generating plants using different systems to create steam. A nuclear power plant uses uranium fuel to produce nuclear fission which heats water into steam to drive the turbine that ultimately produces electricity.
There are many different reactor types used in nuclear power plants world-wide to create nuclear energy. Two of the most common reactors are Pressurized Water Reactors and Boiling Water Reactors, both of which are light water reactors (LWR). Light water reactors use ordinary water to cool and heat the nuclear fuel. LWRs are generally the most economical and common type of reactors.
Pressurized water reactor (PRW)
Nuclear fission produces heat inside the reactor. That heat is transferred to water circulating around the uranium fuel in the first of three separate water systems. The water is heated to extremely high temperatures, but doesn’t boil because the water is under pressure. The water within the primary system passes over the reactor core to act as a moderator and coolant but does not flow to the turbine. It is contained in a pressurized piping loop. The hot, pressurized water passes through a series of tubes inside the steam generator.
These tubes are surrounded by another water system called the secondary or steam generating system. The heat, but not the water, from the primary coolant is transferred to the secondary, system which then, turns into steam.
The primary and secondary systems are closed systems. This means the water flowing through the reactor remains separate and does not mix with water from the other systems.
The steam is pumped from the containment building into the turbine building to push the giant blades of the turbine. The turbine is connected to an electrical generator.
After turning the turbines, the steam is cooled by passing it over tubes carrying a third water system called the condenser coolant. As the steam is cooled, it condenses back into water and is returned to the steam generator to be used again and again.
Boiling Water Reactors (BWR)
Unlike the PWR, inside the boiling water reactor, the primary water system absorbs enough heat from the fission process to boil its water. In contrast to the PWR, the BWR uses only two separate water systems as it has no separate steam generator system. This steam and water mixture rises to the top of the reactor and passes through two stages of moisture separation. Water droplets are then removed and steam is allowed to enter the steam line. The steam is directed to the turbine. The turbine begins to turn within the generator and electricity is produced.
Once the turbines have turned, the remaining steam is cooled in the condenser coolant system. This is a closed water system. Heat from the steam is absorbed by the cool water through heat transference. The water within the two systems does not mix. Once through the condenser system, the water is recycled back into the reactor to begin the process again.
A Duke Engineer Shares His Experience In Japan Months After the Earthquake
In this picture, the tsunami approaches the Fukushima Daiichi plant. (TEPCO)
It’s one thing to read accounts and watch video of the violent and powerful natural disasters that occurred in Japan a year ago, but it’s quite another to actually see the aftermath firsthand. Just ask John Richards. He visited Japan two months after the devastating earthquake and tsunami. A Duke Energy structural engineer with a specialization in earthquakes, he went as part of a group put together by the Electric Power Research Institute (EPRI) to study the seismic damage at the Fukushima Daini nuclear plant, which is about seven miles south of Fukushima Daiichi. Below, John Richards shares his experience in Japan with Shedding a Light.
Two months after the March 11 earthquake and tsunami, EPRI assembled a special group, of which I was included, to send to Japan. This was my second trip to Japan. In 2007, I was one of 30 engineers and scientists from around the world who toured the Tokyo Electric Power Company (TEPCO) Kashiwazaki-Kariwa Nuclear Power Plant in Japan five months after it experienced a 6.6-magnitude earthquake. Both visits were an excellent opportunity to see how well science and engineering work in a real seismic event. I worked with experts in Japan and from around the world to share our collective knowledge.
At the request of TEPCO, a team was organized by EPRI to inspect Fukushima Daini for earthquake and tsunami damage and to discuss with them their plans for improving the plant in the future. Our team inspected several buildings and evaluated a broad range of mechanical and electrical equipment, including pumps, motors, valves, tanks, batteries, transformers, switchgear, heat exchangers, fans and electrical distribution panels. Following this comprehensive review, we concluded the earthquake didn’t damage any safety-related structures, systems or components.
The group stayed about 50 miles away from the Daini plant in the evenings and rode a bus to the site each morning. We took extensive radiation protection measures, wearing dosimeters to monitor radiation levels from the time we left the hotel each morning until we returned. Once inside the exclusion zone – an area that was evacuated, except for essential personnel, for 12 miles around the Fukushima Daiichi plant – we were required to wear gloves and surgical masks in addition to the radiation monitors.
Inside most of the Daini plant and the office buildings, things were pretty normal and there did not appear to be much damage. Other parts of the complex, however, took a direct hit from the tsunami. We could see where the water had blown through heavy steel doors and poured inside buildings. The water rose as high as 45 feet above sea level. Once the water found its way in, it was relentless in finding every opening and pushing away everything in its path.
Last year’s trip to Japan gave me new insights about the power of a tsunami and how it behaves and what it does to equipment at a power plant. I also have a confirmed respect for the Japanese people who are operating these plants. These workers did an amazing job. This was beyond the kind of events the plants were designed for, and yet the workers at the Daini plant were able to maintain safe shutdown. Based on my experiences at Fukushima Daini last year and at Kashiwazaki-Kariwa in 2007, I learned that Japan’s seismic design practices and seismic qualification methods, while developed differently than those in the U.S., also result in robust nuclear plant designs.
The Fukushima Daiichi and Daini plants faced extreme challenges following the tsunami. Based on that experience, U.S. plants have been performing evaluations to further ensure we can maintain the safety of our plants following extreme conditions. The nuclear industry is very active in sharing lessons learned and operating experience, and I anticipate learning even more from the Japanese earthquake and tsunami as we work together to continuously enhance nuclear operations worldwide.
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Duke Energy Responds to Fukushima
Part 2 – Read part 1 here
Today is the one-year anniversary of the earthquake and tsunami that devastated several regions of Japan and left the Fukushima Daiichi nuclear power plant in distress. In this second part of our two-part series on Fukushima, the NIC highlights many of the actions Duke Energy’s nuclear fleet has taken in response to the events in Japan.
As mentioned in our March 6 post, the nuclear industry has made enhancements to U.S. nuclear plants to ensure they could withstand similar extreme natural events. In keeping with the rest of the industry, Duke Energy continues to monitor the situation closely and learn from it.
Within days of the Fukushima Daiichi incident, we performed walk downs and thorough inspections to reverify each of our nuclear plants was in a high state of readiness to respond to emergency events. We assembled a Fukushima response team to evaluate and respond to information from the Institute of Nuclear Power Operations (INPO) and the Nuclear Regulatory Commission (NRC), and to apply lessons learned from Japan. This team includes technical experts, engineers, seismic specialists and environmental and emergency planning personnel.
During the review process, the team identified enhancements to further augment safety. Items identified were either immediately implemented or are being implemented. Some of the actions taken at Duke Energy-operated nuclear plants include:
- Reverified our ability to respond to threats, natural events, fires and aircraft impact and that we have the appropriate equipment, procedures and staffing.
- Reverified our capability to cope even during a complete loss of AC power.
- Reverified each plant’s capabilities to protect against floods and fires after earthquakes.
- Enhanced our capability to protect fuel stored in used fuel pools against extreme natural events.
- Reverified accessibility to equipment and materials (no obstructions, relocated some equipment) and purchased additional portable equipment to better respond to events that may affect more than one unit at a site.
- Reverified the training qualifications of operations and support staff required to use emergency equipment.
- Confirmed agreements and contracts with external parties to provide fire fighting and emergency response support (such as Memorandums of Understanding with local fire departments).
- Revised our preventive maintenance program to include testing equipment on a more frequent basis.
As we continue to learn from Japan and incorporate those lessons learned, Duke Energy and the U.S. nuclear industry will be focused on implementing the requirements of the new diverse and flexible coping capability (FLEX) program to maintain key safety functions and cope with extreme events using a combination of installed plant equipment, supplemental portable equipment stored on-site and additional capabilities maintained in off-site locations. This also includes:
- Upgrading procedures, providing training and conducting periodic drills for emergencies, severe accidents and extensive damage mitigation.
- Upgrading our capabilities and organizational capacity to address prolonged, multiple-unit and simultaneous events.
- Ordering additional portable equipment such as various types of pumps, high-pressure hoses and communications and satellite equipment.
Duke Energy responded to the events in Japan by renewing our steadfast commitment to maintain the highest levels of safety at each of the three nuclear power plants we operate.
One year later, we pause to reflect on the lives lost and forever changed by the earthquake and tsunami, as well as the indomitable spirit shown by the Japanese people as they put their country back together following the most powerful known earthquake to ever hit Japan.
Further reading:
