The nation’s fleet of commercial nuclear reactors must continue to operate safely, reliably, and with economic efficiency throughout their lifetimes. After that, each reactor must be decommissioned in a way that meets environmental and safety standards.

PNNL research helps meet these objectives with its expertise in materials science, instrumentation and control, risk assessment, physical security, and cybersecurity. This work is supported by the Department of Energy's Office of Nuclear Energy (DOE-NE), the Nuclear Regulatory Commission (NRC), the International Atomic Energy Agency (IAEA), commercial sponsors, and partner national laboratories.

Detecting and withstanding materials degradation  

Materials scientists at PNNL investigate how materials degrade, helping assure that the life of existing reactors can be extended safely. PNNL has the world's leading researchers in the science of stress corrosion and crack (SCC) initiation and growth. They use test rigs to collect material property and degradation data needed to develop degradation models and strategies for detection and intervention.

With industry partners, PNNL also investigates aging electrical cables and develops radiation-tolerant materials for Generation IV reactors. Central to this research are PNNL’s Radiochemical Processing Laboratory (RPL), a Hazard Category 2 non-reactor facility for advancing radiological material processes and solutions, and the Radiological Exposure and Metrology Calibration and Standards Laboratory in the 318 Building.

Probabilistic risk assessment

PNNL nuclear experts conduct risk assessments and safety analyses that underpin the limiting conditions for safe reactor operations, administrative programs, and controls. The experts emphasize decision science, probabilistic risk assessments (PRAs), and systematic analyses that reveal the strengths and weaknesses of the design, construction, operation, and siting of nuclear plants.

PNNL PRA methods have been applied to risk-informed reactor design, to extending NRC’s significance determination process regarding passive components, to reviewing risk-informed license amendment applications to NRC, to the storage and transportation of spent nuclear fuel, and to assessments of external plant hazards, such as flooding.  

Cybersecurity

PNNL staff have expertise in cybersecurity and nuclear power plant operations, including policy development, new technologies, assessments and inspections, and capacity development. PNNL has planned and supported NRC cybersecurity inspections of all licensed facilities. For the IAEA, researchers have developed and delivered training on the security of industrial control systems, radiological materials facilities, and other topics. Researchers also worked with the NRC and IAEA to develop policy and guidance on cybersecurity program inspections, incident response, and other issues.

Meanwhile, PNNL’s award-winning Physical and Cyber Risk Analysis Tool (PACRAT) software helps nuclear plant personnel assess risks of coordinated cyber and physical attacks.

Decommissioning

Decommissioning involves shutting down nuclear plant operations, demolishing the facility, and reducing residual radioactivity to levels set by the NRC. It also involves removing or safely storing any radioactive materials, including spent nuclear fuel. For more than 40 years, PNNL has provided technical decommissioning support to the NRC and international organizations. Staff have helped write more than 70 NRC contractor (NUREG/CRs) publications on technology, safety, and the costs of decommissioning.

PNNL scientists have done research that supports spent fuel disposition from decommissioned plants and have completed many environmental assessments related to decommissioning, including radiological characterizations of decommissioned systems and assessments of doses from residual radioactive contamination.

After the post-tsunami shutdown of Japan’s Fukushima Daiichi nuclear plants in 2011, experts from PNNL provided risk-based prioritization recommendations for cleanup.