GE Hitachi Nuclear Energy deploys first Marathon Ultra technology

With energy companies worldwide seeking new technologies to improve the operational reliability of their nuclear power plants, GE Hitachi Nuclear Energy (GEH) on April 23 announced the first U.S. deployment of its new Marathon Ultra control rod blade (CRB) technology.

Exelon Nuclear, the United States’ largest nuclear energy operator, installed GEH’s Marathon Ultra CRBs at its Peach Bottom Atomic Power Plant in Pennsylvania, about 75 miles southwest of Philadelphia. The power station generates more than 2,200 megawatts of safe, low-carbon electricity, enough to power more than 2 million homes.

Economical and reliable, Marathon Ultra is an innovative, evolutionary technology that is the latest addition to GEH’s portfolio of industry-leading Marathon CRBs, supporting increased reactor availability. CRBs are long, cruciform metal-tube components that contain neutron-absorbing material and are positioned adjacent to nuclear fuel assemblies within the reactor core. Operators remotely adjust the position of these control rod blades to manage core reactivity levels.

The Marathon Ultra product line takes GEH’s proven Marathon design to the next level of reliability and flexibility. Mechanical design margins are increased, enhancing the component's durability during operation. By offering both medium-duty and long-life versions, individual plants may optimize their CRB management strategies, reducing CRB replacement and disposal requirements.

“Peach Bottom has been recognized as one of the top performing nuclear energy stations in the United States, and Exelon is committed to continuing this record of excellence by adopting innovative technologies like Marathon Ultra to help us optimize the performance of our nuclear energy fleet,” said Bill Maguire, Peach Bottom site vice president. “To date, we have been pleased with the performance of Marathon control rod design, so we are excited about the expected benefits of the next evolution in the Marathon Ultra.”

Underscoring the value of nuclear energy in addressing greenhouse gas emissions, energy companies also are extending the operating licenses of their current fleets of nuclear plants and investing in enhancements.

Demand is up for GEH technologies and services such as extended power uprates, which can increase electricity output by up to 20 percent, in addition to GEH’s services for scheduled refueling outages and maintenance.

Nuclear energy is among the few baseload power sources that generate electricity with near-zero greenhouse gas emissions.

“We are pleased to work closely with Exelon to demonstrate how our advanced technologies and services can be deployed to help energy companies around the world achieve greater operational and cost efficiencies with their nuclear power plants,” said Kevin Lagasse, GEH’s senior vice president of nuclear services.

Exelon Nuclear installed two Marathon Ultra MD (medium duty) control rods as “lead use” assemblies in reactor Unit 3 at the Peach Bottom plant during a recent regular refueling and maintenance outage. A lead use assembly is inserted in a reactor core to verify the control rod’s performance.

The new Marathon Ultra offers additional value because of its simplified neutron-absorber tubing design. It also offers enhanced reliability by incorporating a larger gap between the boron carbide (B4C) capsule and the neutron absorber tube, providing extra space to counter any capsule swelling, minimizing potential strains on the absorber tubing.

The Marathon Ultra design also incorporates a high-purity, low-cobalt and radiation-resistant stainless steel absorber tube. These design features help the Marathon Ultra achieve its full, engineered lifetime without mechanical limitation.

GEH designs and builds its CRB product line at its headquarters site in Wilmington, N.C., using advanced materials and manufacturing processes.

Recently, GEH submitted a licensing topical report to the U.S. Nuclear Regulatory Commission for the next offering in the Marathon Ultra product line, the Marathon Ultra HD (high duty), which will offer a longer lifetime for higher-duty applications.