That's what Kirk Sorensen, of Flibe Energy, answers when people ask him if nuclear energy is safe. When explaining the benefits of the Liquid Fluoride Thorium Reactor (LFTR) in the video above, he makes the point that there are many more technologies available to produce electricity from nuclear energy. LFTR is one of these and is different from traditional nuclear energy in use today in that is utilizes a liquid thorium fuel instead of solid uranium fuel that needs to be cooled by water.

Thorium is four times as more common in the Earth's crust than uranium and can also be utilized more efficiently in a reactor. The safety issues in traditional pressurized water reactors stem from the fact that the solid uranium fuel must be cooled by water that is kept at a high pressure. Because of this, safety systems are needed to cover the core with water and cool it in case of an accident.

The LFTR utilizes fluoride salt as a nuclear fuel and therefore doesn't use water for cooling and doesn't have to operate at a high pressure. This means that the core will not 'meltdown' in the case of an accident.
 
Although the current commercial nuclear reactors in operation around the world are safe, there are more advanced nuclear technologies that are even more safe and efficient. We are currently operating only the second generation of nuclear reactors. Imagine if we were still using the second generation of other technologies, like the car or the cell phone? It's time to invest in and develop these advanced nuclear technologies to meet the world's growing energy needs in a clean and sustainable manner.

By Chris Wagener

Nuclear power plants are very different than their fossil fuel counterparts both in how the energy is generated and in the day to day operations. Both nuclear power plants and fossil fuel power plants rely on generating steam to spin a turbine to generate electricity but that is where the similarities end. Fossil fuel plants rely on burning hydrocarbons, such as coal and natural gas, to generate heat to boil water while nuclear power plants rely on fission. Fission generates substantially more energy than the burning of fossil fuels, especially on a pound per pound basis. Inside of a commercial nuclear power plant, fission is the splitting of a uranium and plutonium atoms into smaller atomic pieces.  By splitting these atoms, a large amount of energy is released. A fossil fuel plants works differently by chemically burning hydrocarbons into mainly water and carbon dioxide.

Have you ever seen a train carry loads of coal from a mine to a coal power plant? For a coal power plant to continue to generate electricity, coal must be constantly provided to the boiler.  However, for most commercial nuclear power plants, new fuel is added to the reactor every 12 to 24 months, which denotes the cycle of the reactor. Each cycle, between a quarter and a half the fuel assemblies, which contain the uranium and plutonium for fission, are removed and replaced with new fuel assemblies.  After the reactor is refueled, no fuel is added to the reactor and all the energy that will be generated during that cycle is already there, it only needs to be extracted.  Since the fuel will be in the same location in the reactor for up to 24 months, placement within the nuclear reactor is very important.

For each cycle, engineers start preparing up to a year and a half in advance to determine where the fuel assemblies should be located within the core. The first step in the process is to determine how many new fuel assemblies are required and what the uranium enrichment should be. This is the most important step since the manufacture and delivery of the new fuel takes a long time to ensure that the fuel is properly manufactured and inspected prior to use. Once the fuel is built and delivered, the fuel inventory is set for the cycle and it is very difficult to make major changes to the design.  During this phase, engineers will use computational tools to model the reactor core, which is made up of the fuel assemblies, to determine key characteristics of the cycle.  Once a candidate design has been determined, the safety analysis for the cycle can be performed.

For each cycle, engineers start preparing up to a year and a half in advance to determine where the fuel assemblies should be located within the core. The first step in the process is to determine how many new fuel assemblies are required and what the uranium enrichment should be. This is the most important step since the manufacture and delivery of the new fuel takes a long time to ensure that the fuel is properly manufactured and inspected prior to use. Once the fuel is built and delivered, the fuel inventory is set for the cycle and it is very difficult to make major changes to the design.  During this phase, engineers will use computational tools to model the reactor core, which is made up of the fuel assemblies, to determine key characteristics of the cycle.  Once a candidate design has been determined, the safety analysis for the cycle can be performed.

Due to the unique nature of nuclear power, a wide variety of safety analysis calculations are performed to ensure that the core will meet all the safety requirements as defined by the Nuclear Regulatory Commission (NRC). The calculations performed for each plant are documented in the plant’s Final Safety Analysis Report, describing all the work done to ensure the safety of the plant for a multitude of accident scenarios. Each time the reactor is refueled, engineers will perform calculations using core and plant models to show that in the event of an accident, the regulations set out by the NRC will be met. These regulations exists to ensure the safety of not only the public, but also the workers at the plant. Once the calculations have been completed, engineering reports are generated for submission to the NRC demonstrating that refueling the core continues to meet all the regulations and requirements. The safety analysis calculations that are performed each cycle are done to demonstrate that the plant can operate safely in the worst possible scenarios and during an accident.  

After demonstrating that the core can safely operate for a cycle, engineers will generate the information necessary to operate the plant. This will include information for the plant to show to predict how the reactor will behave when intentional changes are made, such as going up and down in power. In addition, it provides information for the reactor operators to benchmark against their measurements. This is used to help ensure that the models used for the safety analysis were accurate. If any issues arise that indicate that the models were inaccurate at predicting the actual operation of the core, engineers will have to determine whether the plant can still operate safely given the new information. The final set of information provided to the plant before refueling the reactor, is all the information necessary to do what is called startup physics testing.

Startup physics testing is a series of tests performed after each refueling as the reactor is brought to power to demonstrate that the reactor is actually as it was modeled. This shows that the reactor is behaving as predicted and validates the safety analysis. Specific calculations are done each cycle and compared to the results of the startup physics testing. If the plant is within a certain tolerance to the predictions, it demonstrates that the safety analysis is bounding and the plant and continue to operate. If outside of the predictions, engineers must investigate to determine what the issue is and whether or not the plant can continue to operate.

After startup physics testing, the plant will continue to operate until the end of the cycle, assuming that the predictions remain accurate.  During this time, reactor operators will continue to check and ensure the overall safe performance of the reactor.  Once the startup is completed, engineers will restart the process to prepare for the next reactor refueling. Overall, nuclear power plants operate on a cyclical basis with the refueling of the reactor being the main goal. Once the refueling is performed, reactor operators monitor the performance of the core to ensure safe operations while other engineers prepare to refuel the core again.  The breakdown of this cyclical nature is to generate a design for the reactor cycle, demonstrate that the design can operate safely for the entire cycle, provide the necessary data for plant operations, including startup information, and then finally perform startup physics testing to validate all the work performed. After this process is completed, the reactor operators will operate the plant and ensure the safety of the reactor until the next refueling is needed.

By Lenka Kollar

This video from BBC takes you inside a nuclear reactor to understand just how it works. Learn how heat is generated from the splitting of atoms and then turned into electricity for your home.

By Lenka Kollar

Earlier this week, we posted about the new construction at the VC Summer Nuclear Generating Station. The Vogtle Electric Generating Plant in Georgia also started new nuclear construction last year with an addition of two Westinghouse AP1000 reactors. 

Votgle units 3 and 4 plan to start generating electricity in 2017 and 2018. This massive construction project is making history with the materials needed and the amount of people that will be employed. When finished, the four units at Vogtle will make the largest nuclear generating station in the United States. Watch the video below to learn more!

Have you ever wondered how uranium gets from the ground to a reactor to make electricity for your home? Watch the prezi below to find out!

Click here for full size version.

What do you think of when you imagine a nuclear engineer? I bet you don't think of a winemaker.

Meet Joey, the winemaker nuclear engineering. In his research, he tracks the winemaking process by analyzing the elements in each stage, from the soil, to the grape, to the wine. In order to figure out what elements are in each phase, he takes samples and then bombards them with neutrons, thus making the samples radioactive. The gamma rays from the samples are then measured and since each radioactive isotope has a unique gamma signature, you can then figure out what elements are in that sample. Learn more about Joey and his research in the video below.

The I'm a Nuke campaign was formed to change the image of the nuclear engineer and show the public that we are real people with diverse interests. We all became nuclear engineers for different reasons and have done many different things with our degrees and careers.

What questions do you have for Joey?