Advanced small modular reactors (aSMRs) can provide the United States with a safe, sustainable, and carbon-neutral energy source. The controllable day-to-day costs of aSMRs are expected to be dominated by operation and maintenance costs. Health and condition assessment coupled with online risk monitors can potentially enhance affordability of aSMRs through optimized operational planning and maintenance scheduling.Currently deployed risk monitors are an extension of probabilistic risk assessment (PRA). For complex engineered systems like nuclear power plants, PRA systematically combines event likelihoods and the probability of failure (POF) of key components, so that when combined with the magnitude of possible adverse consequences to determine risk. Traditional PRA uses population-based POF information to estimate the average plant risk over time. Currently, most nuclear power plants have a PRA that reflects the as-operated, as-modified plant; this model is updated periodically, typically once a year. Risk monitors expand on PRA by incorporating changes in the day-by-day plant operation and configuration (e.g., changes in equipment availability, operating regime, environmental conditions). However, population-based POF (or population-and time-based POF) is still used to populate fault trees. Health monitoring techniques can be used to establish condition indicators and monitoring capabilities that indicate the component-specific POF at a desired point in time (or over a desired period), which can then be incorporated in the risk monitor to provide a more accurate estimate of the plant risk in different configurations. This is particularly important for active systems, structures, and components (SSCs) proposed for use in aSMR designs. These SSCs may differ significantly from those used in the operating fleet of light-water reactors (or even in LWR-based SMR designs). Additionally, the operating characteristics of aSMRs can present significantly different requirements, including the need to operate in different coolant environments, higher operating temperatures, and longer operating cycles between planned refueling and maintenance outages. These features, along with the relative lack of operating experience for some of the proposed advanced designs, may limit the ability to estimate event probability and component POF with a high degree of certainty. Incorporating real-time estimates of component POF may compensate for a relative lack of established knowledge about the long-term component behavior and improve operational and maintenance planning and optimization.The particular eccentricities of advanced reactors and small modular reactors provide unique challenges and needs for advanced instrumentation, control, and human-machine interface (ICHMI) techniques such as enhanced risk monitors (ERM) in aSMRs. Several features of aSMR designs increase the need for accurate characterization of the real-time risk during operation and maintenance activities. A number of technical gaps in realizing ERM exist, and ...

A key national energy priority to promote energy security is sustainable nuclear power. Nuclear energy currently contributes approximately 20% of baseload electrical needs in the United States and is considered a reliable generation source to meet future electricity needs. Advanced small modular reactors (AdvSMRs) using non-light-water reactor coolants such as liquid metal, helium, or liquid salt are promising mid-to long-term options being explored for added functionality and affordability in future reliable nuclear power deployment. AdvSMRs can offer potential advantages over more conventional technologies in the areas of safety and reliability, sustainability, affordability, functionality, and proliferation resistance. However, a number of technical challenges will need to be addressed before AdvSMRs are ready for deployment, given their potential for remote deployment with minimal staffing, longer operating cycles between planned refueling and maintenance outages, and support for multiple energy applications. In addition, AdvSMRs (like SMRs based on more conventional light-water reactor technologies) will have reduced economy-of-scale savings when compared to current generation lightwater reactors (LWRs). Issues related to AdvSMR deployment can be addressed through cross-cutting RD&D involving instrumentation, controls, and human-machine interface (ICHMI) technologies. Specifically, diagnostics and prognostics technologies provide a mechanism for improving safety and reliability of AdvSMRs through integrated health management of passive components. This report identifies activities and develops an outline of a research plan to address the high-priority technical needs for demonstrating prototypic prognostic techniques to manage degradation of passive AdvSMR components. Concepts for AdvSMRs span a wide range of design maturity, specificity, and concepts of operation, including multi-unit, multi-product-stream generating stations. Key to the development and deployment of AdvSMRs will be the ability to ensure safe and affordable operation of these reactor designs. AdvSMR designs generally place more emphasis on passive systems to assure safety. However, degradation in all passive components will need to be well-managed to maximize safety, operational lifetimes, and plant reliability while minimizing maintenance demands, if reduced economies-of-scale are to be overcome. Traditional approaches such as periodic in-service nondestructive inspections are likely to have limited applicability to AdvSMRs, given the expectation of longer operating periods and potential difficulties with inspection access to critical components. Advanced instrumentation and control (I&C) technologies can provide a mechanism for achieving these goals. However, the significant technology and environmental differences between AdvSMRs and conventional LWRs and the potential for modularized deployment result in unique challenges and needs for advanced ICHMI applications in AdvSMRs. v prognostics is also documented. This assessment, combined wi...

This document was printed on recycled paper.

No abstract

Energy Research and Development Roadmap and industry stakeholders by evaluating optically based instrumentation and control (I&C) concepts for advanced small modular reactor (AdvSMR) applications. These advanced designs will require innovative thinking in terms of engineering approaches, materials integration, and I&C concepts to realize their eventual viability and deployment. The primary goals of this report include:1. Establish preliminary I&C needs, performance requirements, and possible gaps for AdvSMR designs based on best-available published design data.2. Document commercial off-the-shelf (COTS) optical sensors, components, and materials in terms of their technical readiness to support essential AdvSMR in-vessel I&C systems.3. Identify technology gaps by comparing the in-vessel monitoring requirements and environmental constraints to COTS optical sensor and materials performance specifications.4. Outline a future research, development, and demonstration (RD&D) program plan that addresses these gaps and develops optical-based I&C systems that enhance the viability of future AdvSMR designs.The DOE-NE roadmap outlines RD&D activities intended to overcome technical barriers that currently limit advances in nuclear energy. As part of this strategy, DOE-NE is sponsoring research on advanced reactor supportive technologies to reduce the identified barriers. Key challenges that must be overcome include the high capital costs to develop nuclear power plants, maintaining safety performance as the reactor fleet expands, minimizing nuclear waste, and maintaining strong proliferation resistance. AdvSMR designs are a major component of this strategy, because these designs offer a number of unique advantages. The modular and small size of AdvSMR designs naturally lead to reduced capital investments and, potentially, construction savings through factory fabrication. However, new economic and technical challenges accompany the many attractive features offered by AdvSMR designs. Specifically, the modest power output of AdvSMRs does not provide the economy of scale afforded by large reactors. In addition, many of the AdvSMR designs operate at much higher temperatures than lightwater reactors and require instrumentation to withstand harsh, in-vessel environments arising from unconventional, chemically aggressive coolants and unique reactor system configurations.Addressing these I&C challenges will be critically important to the AdvSMR development program to ensure the viability and future success of advanced reactor designs. Solutions will likely be found through evolution of conventional reactor technology, and the development of entirely new concepts. Early pressure/boiling water reactors used conventional I&C technologies (e.g., thermocouples, ionchambers, strain-gauge pressure sensors) to satisfy design requirements. Because these technologies worked well in the relatively low-temperature reactor designs, the demand for alternate I&C technologies was limited. At the time, optical-based reactor monitoring concepts were g...