Get the Facts on Nuclear Power and the Palisades Station

How does a nuclear power plant work?

Steam power plants, whether they are coal or nuclear, use heat to make electricity. They operate like a giant tea kettle, turning water into steam which is then used to turn a generator to make electricity. The only difference between coal and nuclear power plants is that nuclear plants use uranium as the fuel to produce the heat instead of coal.

In a nuclear power plant reactor, water is heated by a process called nuclear fission.

  • Uranium atoms are split when they are struck by neutrons.
  • When the atoms split, they release heat, along with two or three more neutrons.
  • These neutrons then strike other uranium atoms, again causing the atoms to split, release heat and again, two or three more neutrons. This is called a chain reaction.

Heated water travels from the reactor to the steam generators.

  • The water flows through thousands of tubes in the steam generators and then flows back to the reactor.
  • The tubes become hot and transfer the heat to a second system of water that is transformed into steam.

The steam then spins the turbines, which are tied to the generators, which produce electricity.

A series of barriers and safety systems within the plant keeps radioactivity from normal operations inside. The building that contains radioactive fuel and the reactor has thick concrete and steel walls and flooring. The building, or containment, acts as a barrier. It surrounds the reactor and other equipment in contact with highly radioactive materials. The containment structure extends well below the ground. The reactor vessel, where fission takes place, is a thick steel cylinder that contains the fuel assemblies. All nuclear plants are conservatively designed and built with many safety systems and emergency back-ups.

As a nuclear plant, Palisades uses mildly enriched uranium as a fuel to heat water and produce steam that turns turbines to produce electricity

The uranium is contained as pellets in bundles of fuel rods submerged in water inside the steel-reinforced reactor vessel. Subatomic particles, neutrons, strike the uranium nuclei in a controlled reaction called fission. As the nuclei split, heat is released, which boils water and produces steam for the turbines.

Operators control the rate of the reaction (and the amount of heat produced) by raising and lowering control rods inside the uranium bundles. The control rods are made of a material that absorbs neutrons and can be lowered completely into the bundles when it is necessary to shut the reactor down.

The U.S. Nuclear Regulatory Commission (NRC) regulates all nuclear plants, including the issuance of operating licenses. Inspections and tests are performed routinely as a requirement for maintaining an operating license. Periodic training sessions keep Palisades operators familiar with new or changed regulations and procedures.

Is Palisades Nuclear Power Station safe?

Yes. Our first priority at Palisades Power Plant is to operate our nuclear facility safely. Palisades is a safe and secure facility, and we have a Nuclear Regulatory Commission (NRC) license to operate through 2031. We remain in Column 1 – the highest safety category – of the NRC’s Reactor Oversight Process, alongside nearly 80 other safely operating US nuclear plants.

The plant staff is frequently and rigorously trained, drilled and evaluated to respond to any emergency. We have an aggressive inspection process to identify and mitigate minor issues before they become problems. The plant can be shut down and the nuclear fission process stopped in less than two seconds. In fact, the plant will shut down automatically if even one safety component malfunctions.

Structural safety is another intrinsic element to ensure the continued safe operation of our facility. Our systems themselves have multiple physical layers of protection built in:

  1. Nuclear fuel – The fuel itself is actually designed to contain the radioactive gases generated during the fission process.
  2. Reactor vessel - The nuclear fuel is contained inside the reactor vessel. The vessel contains primary coolant that surrounds the fuel under normal and accident scenarios.
  3. Primary coolant system – The primary coolant system cools the fuel under normal and accident conditions. Within the system there are multiple cooling capabilities, each with backup systems in place to ensure the cooling process continues without interruption.
  4. Containment building – This consists of a 1/4 inch thick steel wall surrounded by a wall of steel-reinforced concrete three to thirteen feet thick. This ensures that radioactivity is contained even in the most serious situations.

In fact, Three Mile Island is a perfect example of how well all of these components work. Studies conducted by the University of Pennsylvania at 10 and 20 years following the 1979 incident show there were no adverse health effects from the event, further supporting the claim that the safety systems worked as they should have.

Nuclear power plants are very safe and nuclear power generation has proven to be the safest way to produce large amounts of electricity. The U.S. nuclear industry has operated for more than 30 years without a single nuclear-related fatality.

To read more about nuclear safety at Palisades Nuclear Power Station, click here.

Is Palisades Nuclear Power Station secure?

Palisades Nuclear Power Station is both safe and secure against natural and man-made events. Palisades Nuclear Power Station provides protection at the plant through a highly trained security force, detection capabilities and physical barriers, as well as a highly qualified brigade of first responders and local, state, and federal security agencies.

In addition to skilled security personnel, there are several security barriers on-site within each building and only a limited number of employees are able to access the highly restricted areas. All sensitive areas include cameras, stationary and patrolling armed guards, turn-styles and digital access points, which make it nearly impossible for any individual to go unnoticed.

While the containment structure plays a significant safety role, it also plays a major security role. In addition to the numerous safety measures in place to protect the reactor vessel, the rugged and robust physical structure also plays a key role in protecting the vessel from outside attacks of any kind.

To read more about nuclear safety at Palisades Nuclear Power Station, click here.

Can a nuclear plant explode?

No, a nuclear explosion cannot occur at commercial nuclear plants. Fuel for nuclear plant uranium is mined from the earth and then goes through the process of "enrichment." From that process, comes uranium-235 (which makes up approximately 4% of nuclear fuel used at a commercial facility) and uranium-238 (which makes up the other 96% of the fuel). In order to have an explosion, unranuim-235 must make up nearly 100% of the fuel. Scientifically speaking, an explosion at a nuclear facility in the U.S. would counter the laws of physics.

Can Chernobyl happen here?

No. Though people often compare U.S. nuclear facilities to Chernobyl, U.S. nuclear facilities have several safeguards that Chernobyl did not, including a high-integrity containment building and multiple safety systems.

There are several significant distinctions that should be understood:

  1. There was no containment structure at Chernobyl. Instead, there was a graphite cylinder with a tin roof that surrounded the nuclear fuel. All U.S. plants are required to have a high-integrity containment structure in place.

  2. Safety systems at the Chernobyl facility were disconnected prior to the explosion.

  3. The explosion at Chernobyl was a hydrogen explosion, not a nuclear explosion. Hydrogen was used to generate the heat that powered the turbines and generators to create electricity. In the U.S., steam is used to operate the turbines.

  4. Once the top of the reactor was literally blown off by the hydrogen explosion, irradiated graphite was scattered into the distance which is why the effects were seen so far away. The radioactive isotopes from the nuclear fuel (because of their weight) remained in the reactor.

The type of uranium used at a commercial facility in the U.S. and the structure of the containment dome required to operate a plant here would rule out the possibility of any Chernobyl-type event. That type of plant could NOT be - nor has one ever been - licensed in the U.S. because of the substantial design flaws at Chernobyl. Thus, the accident that occurred there could not be duplicated here in the U.S.

Consider the only nuclear accident that has occurred in the U.S. in the 35-year history of nuclear power, Three Mile Island - the containment dome successfully contained the radioactivity preventing dangerous exposure levels from ever leaving the core, much less reaching the public. And, even though no one was harmed in that accident, the industry learned from the event and implemented even more safeguards in the form of plant equipment and training.

How is spent fuel stored at Palisades Nuclear Power Station?

Spent fuel is stored in either our spent fuel pool or inside federally approved dry casks. The fuel stored in both the pool and dry casks is well protected by multiple robust barriers. Our spent fuel pool has a stainless steel liner surrounded by three to four feet of concrete. It is designed with its own redundant safety features to ensure that fuel integrity will not be compromised.

Spent fuel is also stored in federally approved dry casks, where it awaits shipment to a federal nuclear waste repository. Dry fuel storage has been used at Palisades since 1993 and is a safe and secure method for storing used fuel. The casks are very robust and are designed to prevent fuel damage during accident conditions such as tornados, floods, snow and ice, earthquakes, or explosions.

For additional information on dry fuel storage, visit the dry fuel storage section of our Web site.

What is pressurized thermal shock?

The Nuclear Regulatory Commission (NRC) has strict rules, regulations and limits for all aspects of nuclear plant operations. This includes a program to monitor reactor vessels and the potential impact of a rare accident scenario — pressurized thermal shock — in which a large amount of cold water would be injected into the reactor resulting in rapid cooling of the reactor vessel. Every pressurized water reactor plant in the nation is required by the NRC to continually update its calculations to confirm reactor vessel strength. This means every plant must conduct periodic reactor vessel inspections and analyze reactor vessel samples.

Palisades regularly conducts these inspections and analysis, and most recently completed an inspection during our refueling outage in early 2014. An updated evaluation will be submitted to the NRC for review in the summer of 2014. Palisades has every reason to believe that the test results will again demonstrate the safety and strength of the plant’s reactor vessel – which will enable us to continue operating through the end of its license in 2031.

The Palisades plant is safe and the reactor vessel meets all current NRC requirements. Palisades is committed to the health and safety of everyone in the community, including our families and friends in the public as well as our own employees. As part of that commitment, we have a rigorous inspection and evaluation program in place to ensure our reactor vessel meets or exceeds all NRC requirements, even in the most unlikely scenarios.

What is the emergency plan for Palisades Nuclear Power Station?

Entergy's unrelenting commitment to nuclear safety extends beyond the plant’s boundaries. Palisades has a detailed plan for responding in the unlikely event of an emergency that could affect the public. We test the plan regularly with the participation of local and state response organizations. As part of this constant state of readiness, information booklets about emergency planning are updated and sent to residents within a 10 mile radius of Palisades every year. Read more in the 2013-2014 Palisades Emergency Preparedness booklet.

At Entergy, there is no higher priority than operating our power plants safely. This responsibility also includes preparing for the unlikely event of a nuclear emergency. Working closely with national, state and local emergency management agencies, Entergy's nuclear plants have developed detailed emergency plans that address actions to be taken to protect the health and safety of the public up to 50 miles from any one of our plants. These plans are practiced routinely with oversight from the U.S. Nuclear Regulatory Commission (NRC) and the Federal Emergency Management Agency (FEMA).

Has security been updated at Palisades Nuclear Power Station since September 11, 2001?

Since September 11, 2001, a focus on security has become increasingly visible everywhere, including the security measures on site at Palisades Nuclear Power Station. Since that time, additional security measures at Palisades include increased surveillance activities, greater restrictions on persons and deliveries entering the site, and further support from and coordination with local, county, state and federal law enforcement authorities.

Is the age of Palisades Nuclear Power Station a security or safety factor?

No. Palisades is a safe and secure facility, and we have a Nuclear Regulatory Commission (NRC) license to operate through 2031. Opponents charge that Palisades Nuclear Power Station's age renders the plant less safe than newer plants. The fact is that the external structure of Palisades Nuclear Power Station was constructed to last well beyond its original license of 40 years. Internally, millions of dollars in upgrades have been made to the plant —to the point where its parts are almost entirely new.

There is also routine maintenance that occurs every day to ensure the safe continued operation of the plant and to minimize the need for unscheduled shutdowns.