Ensuring Safe Operations
Plant systems and components at Limerick are routinely tested and inspected to ensure continued safe and reliable operations and performance. Like all nuclear plants, Limerick is subject to a rigorous program of U.S. Nuclear Regulatory Commission (NRC) oversight and inspection of Limerick's preventive and corrective maintenance, equipment replacement and extensive equipment testing programs. These programs ensure nuclear plant equipment continue to meet safety standards, no matter how long the plant has been operating.
All safety equipment at nuclear energy plants have intended safety functions and are designed to respond in the safest manner to any condition at the plant. Certain equipment is designed to automatically shut down the plant if the need arises due to a condition outside of normal operations.
Limerick, like all U.S. nuclear energy plants, is based on a "defense-in-depth" design which means there are redundant, diverse and reliable safety systems to supply water to the reactor core. Every safety system has at least one independent back-up system and many have multiple back-up systems – if one system should fail, another automatically backs it up. Plant safety systems are powered by multiple, redundant power sources to ensure safe operations even in extreme environments.
Redundant and Multiple Barriers
Nuclear energy plants are built with redundant and multiple physical barriers to contain radioactive materials and prevent them from entering the environment. The first barrier is the fuel itself: the solid, ceramic uranium pellets.
The pellets are sealed in metal fuel rods. The fuel rods are made of the metal alloy zirconium, which resists heat, radiation and corrosion. The rods are bundled together into fuel assemblies. The fuel assemblies make up the nuclear reactor core. The reactor core is inside the reactor vessel, which has steel walls that are about six inches thick. The reactor vessel sits inside a containment structure, which is made of steel-reinforced concrete and is about five feet thick. All of these layers are inside the reactor building.
Limerick's reactor building is made of steel-reinforced concrete, about four feet thick. All of these barriers are designed to contain radioactive materials and prevent them from entering the environment.
Investing in Our Employees
Our employees are personally committed to safety. They are highlys-skilled workers and all site employees participate in initial and continuous training programs. Exelon Nuclear invests in training programs for our employees to ensure they can safely operate, maintain and improve the performance of the plant. Training programs are established to support job performance and continuous improvement in our employees to ensure safe and reliable plant operations and to protect the health and safety of the public and plant personnel.
Limerick's operations and maintenance and technical training programs are accredited by the Institute of Nuclear Power Operations (INPO).
The plant’s reactor operators and senior reactor operators receive more than 200 hours of training each year. Nearly half of their training is conducted in a full-scale electronic simulator of the control room. Initial training includes 12 weeks in the classroom, 25 weeks in the control room simulator and 16 weeks of on-the-job training. Additionally, once licensed by the NRC, operators continually train by spending one week in the control room simulator for every five weeks spent on shift in the control room.