Nuclear Fuels & Critical Structures

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With its purchase of ANATECH Corp. in 2013, Structural Integrity Associates adds over 400 combined years of advanced expertise in Nuclear Fuels related services and Structural Engineering to its already diverse range of services. Our highly-trained consultants support projects with state-of-the-art methodologies to achieve continual improvement and project success. We believe that linking technical excellence with practicality provides the formula for effective, efficient and innovative solutions to the most complex problems within these industries and others.

Outage Services

We understand that outages are a critical time at power plants. You need knowledgeable, responsive experts who have experience helping solve problems.

Structural Integrity has dedicated outage response teams who are available to assist on emergent issues that arise during a plant outage. Our experts are backed by over 30 years of nuclear power plant experience helping resolve problems that otherwise derail outages. Structural Integrity’s value is helping power plant owners save time and money on issues that are difficult to solve and require the responsiveness and experience that we uniquely deliver.

We routinely provide outage expertise in the following areas:

  • Operability Evaluations: Assist in interpreting whether technical specification equipment is operable based on design basis requirements.
  • Flaw Tolerance Analysis: Assess existing and postulated future growth of flaws found during inspections, from primary system to balance-of-plant components.
  • Repair/Replacement Design and Relief Requests: Provide repair/replacement designs and supporting analyses commensurate with design requirements, as well as licensing documents and regulatory interface support when needed.
  • Welding, Materials and Fabrication: Provide consultation on materials issues including welding and other fabrication processes, as well in-process damage assessment and related corrective measures.
  • Vibration Monitoring and Analysis: Assess potential for and mitigation of high-cycle fatigue including in-situ monitoring, identification of corrective measures, and follow-up confirmatory testing .
  • NDE Support: Provide highly-responsive advanced NDE capabilities for the performance of critical inspections and independent Level III reviews of NDE work performed by others.
  • Third-Party Reviews: Provide independent review of component condition assessment, as well as design, fabrication, and inspection work performed by others.
  • Failure Analysis/Root Cause Analysis: Assess damage mechanisms contributing to failures of components based on field evidence or using our Materials Test Center or third-party facilities, and apply rigorous methods to identify probable causes and root causes as needed to preclude repeat failures.
  • Water/Reactor Chemistry: Identify conditions related to potential start-up chemistry exclusions that impact plant start-up, and the measures needed to mitigate them.
  • Radiation Source Term: Assist with measures to address high concentrations of activated corrosion products that impact outage activities.
  • Fuel Failures: Perform related root cause and extent of condition evaluations, including conduct of field inspections, as well as third-party review of fuel vendor and utility evaluations of fuel failures.
  • Electrical equipment/EQ: Provide the support needed to verify design bases; analyze component and system operation, system transient event response, and environment conditions; and qualify and extend the life of electrical equipment.

Electrical Consulting Services

When it comes to verifying design bases, analyzing component and system operation, system transient event response, assessing conditions, qualifying and extending the life of electrical equipment, Structural Integrity has the solutions.

Our specialties include:

We view electrical components through a multidisciplinary lens that integrates our power industry experience in environmental requirements, materials science, chemistry, physics and mechanical engineering, all coupled with an extremely detailed understanding of equipment and systems operation. This nuts-and-bolts knowledge is matched by a real-world understanding of the regulatory environment.

Structural Integrity has the experience and depth of knowledge to support plant efforts to lower the cost of operations and maintenance as a part of Delivering the Nuclear Promise. We have significant experience in the operation and function of key plant equipment to support strategic efforts to benefit our clients.

Some key areas include:

Through our MAPPro Suite of advanced engineering applications, we can offer a full-suite approach to support both mechanical and electrical component aging and asset integrity management. Mappro also provides plant equipment Configuration Management support by providing a data resource designed for use in Maintenance Work Planning, Procurement, Operations, across multiple Engineering Programs.

To date, over 40 nuclear stations have implemented various forms of our MAPPro applications; so the good news is that your station likely already has a license for the program. Such broad utilization provides significant economies of scale in the implementation and management of key aging asset programs. In turn, the technical capabilities within MAPPro informs and optimizes the management of the assets resulting in a high return on investment. Using a single suite provides a significant opportunity for overall program cost reduction through:

  • Common interface, look and feel, making it easier to transition personnel between applications
  • Lower training costs due to familiarity with other applications in the Suite
  • Lower training delivery costs due to commonality of modules
  • Reduced annual fees when compared to separately provided modules from multiple suppliers
  • Data trending tools that facilitate planning and cost optimization
  • Ease of management understanding of reports and data due to common features

Case Study

Standby Liquid Control System Test Tank

SI used finite element analysis to evaluate the as-built condition and seismic retrofit of a small tank. The tank was evaluated for seismic load combinations including seismic and dynamic loads imposed by attached piping and including the effects of sloshing of the contained fluid. The evaluation showed that the proposed retrofit successfully restrained the tank against excessive seismic displacement. Calculations were performed to the applicable AISC design standard.

Fatigue Failures in Branch Connection Welds

The U.S. Nuclear Regulatory Commission issued Information Notice 2015-04: Fatigue in Branch Connection Welds to raise awareness of unexpected fatigue failures on branch connection welds. Recent operating experience suggests that these failures are caused by resonance conditions. In-service inspection programs cannot proactively identify damage from this form of high-cycle fatigue before failure occurs.

After years of development, we are the first to offer a proactive Branch Line Fatigue Failure Prevention Approach to help owners break the failure cycle and keep plants operating. Our various levels of support can be customized to solve each of your unique issues.

Small Bore Piping Screening – Implementing changes in operation (load following, power uprates, etc.) requires significant planning and engineering assessments. We specialize in vibration assessments, including risk ranking programs that proactively identify affected piping and components.

Vibration Acceptance Criteria Development – We specialize in developing acceptance criteria using ASME's Operation and Maintenance (O&M) guide to provide various thresholds for operation (warnings and alarms). These analyses, in conjunction with vibration monitoring, provide advanced warning before approaching material endurance limits and added confidence by knowing your operating stress levels and fatigue margin. If there is uncertainty in a design or new operating parameters, this analysis provides additional insight needed to fully quantify fatigue susceptibility.

Startup Testing and Monitoring – During startup activities you want an expert onsite to ensure the right data is available and, more importantly, to assist with decisions for continued power ascension. Our team can provide monitoring systems with warning and alarms, quickly assess trends, and use impact testing to de-tune piping from potential resonance conditions. We can take days off the piping modification process turning around testing, weight/support additions, and verification in less than 48 hours.

Vibration Data Analysis - Every station has the capability to collect vibration data, but there are many nuances for analyzing piping data compared to rotating equipment data. We specialize in analyzing piping data with the ability to use your raw (waveform) vibration data; relating relative energy levels, frequency response, vibration directionality, and operational effects to clearly illustrate trends and make informed decisions.

Instrumentation - We offer many acquisition sensor types including temperature, acceleration, strain, and displacement. Newly developed systems minimize the number of electrical penetrations required for inside containment and reduce dose during installation and monitoring evolutions. Our experts manage the installation process from procurement through sensor checkout -providing superior data fidelity for each and every sensor.

Modal Analysis - Most code stress analyses only evaluate deadweight, thermal, pressure, and earthquake loads. They often overlook modal analysis (calculating natural frequencies) and forced vibration loads. These analyses requires careful tuning of the model stiffness, especially for small bore piping, and often vibration data to benchmark a model's response. We have integrated these activities into our approach to provide accurate modal predictions and proven fatigue resistant designs.

Root Cause Evaluations - Structural Integrity's capabilities in support of your root cause analysis are second to none. We offer a complete range of root-cause and failure analyses, varying in complexity from one or two specialists to a multi-discipline team. By combining our expertise in materials engineering, stress and fracture mechanics, vibration analysis and laboratory analytical services in addition to our decades of experience leading and supporting root cause analyses of unique and industry-first failures, we help ensure that the true cause(s) of the failure are identified and solved the first time.

Training - With changes occurring throughout organizations and expertise often leaving without sufficient knowledge transfer, Structural Integrity's industry recognized experts have developed training classes that can be provided in one of our offices or at your site to equip engineers with the knowledge needed to optimize your vibration program.

With our solutions currently in place at 30 percent of the U.S. nuclear fleet, our approach is proven - and second to none.

For additional information, please continue searching through the links below, or contact .


Nuclear External Hazards

Every nuclear facility and its structures, systems and components (SSCs) exist within a unique site environment that must cope with a variety of external hazards. The scope of external hazards that may potentially affect any given site is enormous: storms with accompanying extreme winds, lightning, hail, snow and ice, and flooding with consequential sedimentation and erosion; earthquakes, causing vibratory ground motions, ground rupture, soil settlement and liquefaction, tsunamis, and incidental or collateral effects; landslides and ground failures such as sinkholes; transportation accidents, industrial accidents, overpressures from explosions and impacts from missiles; droughts; fires; bio-fouling; electromagnetic interferences or pulses; deliberate acts and terrorism; as well as site-unique hazards. Fortunately, for any site, many of these hazards can be suitably screened out or otherwise systematically, carefully eliminated and/or prioritized, leaving a comparatively few for more detailed analysis by deterministic and/or probabilistic means.

Our expertise and experience encompasses screening and prioritization of all types of external hazards based on their potential and/or effects, as well as detailed deterministic and/or probabilistic assessments of the important categories of external hazards and site-unique situations. Our services include detailed safety evaluations and reviews for existing facilities, as well as siting studies, safety analyses, preliminary and final design investigations and planning for new facilities.

Fulfilling an assessment for any external hazard requires the following: sufficient qualitative and quantitative understanding of the fundamental phenomena causing, and associated with, the hazard; modelling the severity-likelihood characteristics of the hazard (i.e., conducting a hazard analysis) in a manner useful for engineering design, analysis and decision making; understanding and modelling the effects and consequences of the hazard on SSCs and the overall facility.

Structural Integrity provides a full set of capabilities in assessing external hazards:

  • Siting studies, safety analyses and project planning
  • Research and site reconnaissance of site-relevant external hazards
  • Screening and prioritization of external hazards
  • Deterministic and probabilistic hazard analysis / quantification
  • Simplified to detailed response analysis of soils and soil structures; structural systems; fluid systems; interacting elements; and components/equipment
  • Response analysis of plant systems to external hazards
  • Expert review, advising and testimony
  • Evaluation of impacts on plant operations and economics for executive decision making and insurance studies (in addition to safety investigations)

Where appropriate to complement our internal strengths, Structural Integrity regularly partners with other leading companies to provide an even broader range of capabilities to meet your specific needs.

Our diverse technical knowledge, capabilities and partner-collaborations in the area of external hazards provide our clients with world-class engineering and services for effectively evaluating, demonstrating and/or improving safety, as well as achieving more effective plant economics.

Structural Integrity has and currently leads and performs, a number of technical and consulting projects pertaining to equipment qualification, tornado-generated missile impact, seismic and flooding hazards, tsunami hazards, and aircraft crash and explosion effects on facilities. Experts at Structural Integrity actively participate in key industry events and with relevant industry organizations concerned with external hazards, contribute to associated ASME committee activities, and develop and promote new capabilities for advancement of methodology pertaining to external hazard evaluation, risk assessment and risk management.

Related Resources


License Renewal/SLR

General Overview

As a safe, efficient, and clean source of electricity, nuclear energy continues to play an important role in meeting our world's growing need for electricity. After a U.S. nuclear reactor has been in operation for 40 years, operating licenses may be renewed for additional 20 years periods. More than 75 plants in the US have already renewed their licenses to 60 years of operation and some owners are now interested in operating their plants for an additional 20 years (an 80-year service life) - termed Subsequent License Renewal or SLR. Structural Integrity Associates, Inc. (SI) can help ensure your plant will meet the demands of a longer operating life, and make your journey to license renewal and SLR a smooth one.

SI was originally founded in 1983 to help utilities build and operate nuclear plants safely with a focus on the prevention and control of failures. SI's support for license renewal is a natural extension of that initial focus and one we have been providing since the first plants sought approval for operation to 60 years. SI's fundamental understanding of degradation mechanisms and experience in managing these mechanisms has led many nuclear utilities to turn to us for help in extending the life of their plants.

SI has been a key consultant to nearly every U.S. utility that has sought to extend nuclear plant operating licenses to date and remains actively involved with industry efforts coordinated through both EPRI and NEI. The range of SI's License Renewal and SLR services has grown significantly over time and now can address nearly every aspect of a License Renewal / SLR project. Having grown alongside the nuclear energy industry, SI is a powerful partner through every step of the license renewal process.

Technical Overview

The filing of your license renewal application, successfully navigation of the NRC review process, and implementation of required aging management programs involves both a complex regulatory process and technical issues. From start to finish, SI can make this daunting task more manageable by helping you with all license renewal evaluations and associated documentation, excluding the environmental review.

SI provides a full menu of license renewal services in the following areas:

  • LRA/SLR Assessment and Recommendation Report
  • Project Plan and Guideline development
  • License Renewal Application preparation and/or review (including FSAR Supplement and Technical Specification change support)
  • Integrated Plant Assessment
  • Aging Management Review
  • TLAA and Exemptions
    • Metal Fatigue (including evaluation of environmental effects)
    • HELB evaluation
    • Neutron Embrittlement
    • Concrete Containment Tendon Prestress
    • Containment Liner Plate, Metal Containment, Penetration Fatigue
    • Plant-Specific TLAAs
  • Aging Management Programs (AMPs)
    • Development and implementation
    • Effectiveness Assessments
    • Operating Experience Reviews
  • GALL Gap Evaluation and Disposition to address changes since LRA approval
  • License Renewal Commitment Implementation Support
  • Regulatory Support (including RAI support)

To complement our internal strengths, SI regularly partners with other leading companies to provide a broad range of capabilities that target your specific needs. Our nuclear industry partners include TransWare, Anatech, SC Solutions and AZZ/WSI.

Our technical know-how and knowledge of the license renewal process bring plant owners a greater confidence in a successful license renewal or SLR.

Market/Topic Specific

SI has performed technical and consulting work for all nuclear-fueled reactor types in the U.S., as well as CANDU reactors. The experts at SI actively participate in the key industry organizations relevant to license renewal and SLR, including the Nuclear Energy Institute (NEI) and Electric Power Research Institute (EPRI), as well as ASME, NACE, ASNT and other standards organizations, and have developed new technology and software that have become nuclear industry mainstays.