Products & Technology

Smart-LCM™ Optimization of Nuclear Component Maintenance & Life Cycle Strategies

When planning maintenance activities for major nuclear components such as steam generators and other nuclear facility assets, decision making can seem daunting and subjective, and may result in differing opinions by different stakeholders. DEI’s SMART-LCM™ tool simplifies the decision making process by simultaneously projecting future thermal performance, material degradation, component reliability and other technical metrics for the component of interest, while combining economic analysis of the costs and downtime anticipated for candidate maintenance strategies. This analysis is then simplified into actionable recommendations that support objective decision making. To date, SMART-LCM™ studies completed by DEI have saved nuclear utilities on the order of one hundred million USD in O&M costs through optimized life cycle management for nuclear components.

Primary Chemistry and ALARA Assessments

The goals of properly designed primary chemistry and ALARA programs are to ensure material and fuel integrity and minimize radiation exposure to plant workers. To assist utilities in objective decision making, DEI offers independent assessments for PWRs, BWRs and CANDU units to isolate and quantify the technical/economic merits of various primary chemistry and ALARA practices. These studies are relatively inexpensive and typically identify strategies for reducing plant dose rates, shortening outage schedule and/or achieving equivalent performance with reduced O&M costs. These assessments typically include evaluation of startup, shutdown and operational chemistry practices, use of chemical additives such as zinc and noble metals, resin selection and filtration / demineralization practices, and benchmarking against US and non-US operating experience.

J-Groove Adaptor SCC Probabilistic Evaluation for Reactors (JASPER™)

Stress corrosion cracking (SCC) affects populations of J-groove welded Alloy 600 nozzles such PWR reactor vessel bottom-mounted nozzles (BMNs). Because replacement of BMNs in a reactor vessel with SCC-resistant materials is not a practical option, peening surface stress improvement is the primary technique used for SCC mitigation. JASPER™ is a probabilistic fracture mechanics code developed by DEI to assist utilities in predicting the occurrence of SCC in susceptible nozzle populations, assessing the benefits of peening mitigation, and identifying the optimal timing of peening on a plant-specific basis. JASPER™ simulates SCC initiation and growth both in the Alloy 600 nozzle base metal and the Alloy 82/182 J-groove weld metal and is calibrated using the most relevant operating experience.

Reactor Vessel Tensioning Optimization

PWR and BWR reactor vessel heads have traditionally been tensioned with multi-pass procedures using several hydraulic tensioners. Typically two to three passes are required to achieve stud elongation tolerances, including time consuming adjustment passes. Through analysis, DEI developed optimized tensioning procedures which allow reactor vessel tensioning to be achieved in a single pass, justify increased stud elongation tolerances, and minimize the travel distance that each tensioner must be moved around the head (typically reducing this travel distance by a factor of three). These optimized tensioning procedures typically save 8-12 hours of critical path time during refueling outages and reduce radiation exposure to workers during tensioning activities. DEI has developed optimized tensioning procedures for more than 80 nuclear plants worldwide.

Telepath™ Automated Radiation Mapping System

Radiation surveys at nuclear power plants are created using labor-intensive data collection processes, and these surveys are taken at discrete points in time such that they become obsolete as radiological conditions change. Telepath™ is an innovative hardware/software platform that utilizes the plant’s existing teledosimetry system, along with location tracking devices worn by individual workers to passively “crowdsource” radiation maps as plant staff perform their normal work activities. This dramatically reduces the radiation protection resources required and ensures that high fidelity, up-to-date radiation maps are available to radworkers in real time and in an intuitive format that improves radworker practices. Telepath™ integrates seamlessly with the plant’s existing teledosimetry system and login practices used when workers enter a radiologically-controlled area.