Nuclear Science


Light Water Reactor Sustainability

Mitigation Technology

Dr. Jeremy Busby leads R&D efforts by ORNL and other laboratories directed at understanding and predicting long-term environmental degradation behavior of materials used in nuclear power plants and providing data and methods that can support safe plant operation under extended service conditions.

The Department of Energy Office of Nuclear Energy has identified four objectives that ensure nuclear energy remains a compelling and viable energy option for the United States. Objective 1 (develop technologies and other solutions that can improve the reliability, sustain the safety, and extend the life of the current reactors) is being accomplished through the Light Water Reactor Sustainability (LWRS) Program.

ORNL provides technical leadership to the LWRS Program through the Materials Aging and Degradation Pathway. This technology pathway (led by Dr. Jeremy Busby) is focused on developing the scientific basis for understanding and predicting long-term environmental degradation behavior of materials used in nuclear power plant (NPP) structures, systems and components (SSCs), and providing data and methods to assess and enhance the performance of SSCs essential to safe and sustained operation of the plants. The Materials Aging and Degradation Pathway at ORNL collaborates with representatives of DOE national laboratories (Idaho National Laboratory, Argonne National Laboratory, Sandia National Laboratories and Pacific Northwest National Laboatory), nuclear industry (Electric Power Research Institute, reactor vendors and owners groups) and international organizations (International Atomic Energy Agency, Materials Aging Institute and others) on materials R&D activities directed at understanding and mitigating the aging effects on SSCs from extended service. The pathway R&D products will be used by utilities, industry groups and regulators to define operational and regulatory requirements/limits for materials in plant SSCs subject to long-term operation conditions.

The major R&D areas under the Materials Aging and Degradation Pathway include the following:

  1. Reactor Metals – Numerous types of metal alloys can be found throughout the primary and secondary systems of NPPs. Plant operating environments create material degradation mechanisms that may be unique or environmentally exacerbated. Research projects in this area will provide a greater technical foundation to help determine remaining useful life for metallic components exposed to long-term operating environments.
Reactor Metal

Nuclear power plant operating environments create material degradation mechanisms that may be unique or environmentally exacerbated. In this figure, Irradiation-Assisted Stress Corrosion Cracking has resulted in cracking at the head of a baffle bolt.

  1. Concrete – Large areas of most NPPs have been constructed using concrete. However, there is currently little or no data on long-term concrete performance in these plants. As such, the objective is to assess the long-term performance of concrete in nuclear applications.
  2. Cabling – Cable aging is a concern that currently faces existing NPPs. Degradation of cables is primarily caused by long-term exposure to high temperatures. Additionally, stretches of cables that have been buried underground are frequently exposed to groundwater. Wholesale replacement of cables would likely be a “show stopper” for long-term NPP operation.
  3. Nondestructive Evaluation (NDE) – The understanding of aging-related phenomena and their impacts on SSCs is expected to be a significant issue for any NPP planning for extended service. The management of those phenomena and their impacts can be better enabled by improved methods and techniques for the detection, monitoring and prediction of SSC degradation.
  4. Mitigation Technologies – These technologies include weld repair, post-irradiation annealing, and water chemistry modifications.

In addition, the Materials Aging and Degradation Pathway is actively involved in efforts to harvest selected materials (RPV metals, concrete and low-voltage cabling) from the decommissioned Zion plant for conducting aging effects R&D and a joint DOE/industry project to study and identify improved inspection and aging prediction techniques from NPPs currently in their extended service periods.

ORNL personnel also contribute to LWRS Program activities in the areas of program management, reactor fuel with improved accident-resistance characteristics, advanced instrumentation and control technologies, and component aging modeling & simulation to support a risk-informed decision-making process on available plant margins.

For more information, contact:

R&D Staff, Advanced Reactor Systems and Safety
Don Williams

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