Given the aforementioned design differences from large LWRS not only for SMRs in general but for A-SMRs in particular, it is important to evaluate and then determine if existing assessment methods for certain key areas as developed for large LWRs are applicable or require modifications for use for A-SMRs or if new methods are required. Presently, the three areas where assessment methods are being evaluated and/or developed for A-SMRs in the ART program include the following:
• probabilistic risk assessment (PRA);
• safeguards and security; and
• economics
The overall objectives for examining and developing PRA methods at an early stage for applying them to A-SMRs is to (1) aid in early conceptual design efforts for evaluating design options from a risk and reliability standpoint and (2) formulate an A-SMR PRA framework to provide resources for evaluating future designs and assisting in licensing activities by developing quantitative methods and tools for analyzing A-SMR risks [7].
In looking at future A-SMR designs, the opportunity exists at the outset for integrating safeguards and physical security protection early on in the design process. In NRC’s SECY-10-0034, Potential Policy, Licensing, and Key Technical Issues for Small Modular Nuclear Reactor Designs [8], NRC notes that
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Table 14.3 Summary of ART regulatory and safety-related R&D projects
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Research areas
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Research scope
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Licensing development
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Regulatory framework for advanced (non — LWR) reactors
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Develop (1) guidance needed to apply the General Design Criteria (GDC) of Appendix A to 10 CFR 50 to advanced non-light water reactors and (2) a proposed set of generic GDCs as derived from 10 CFR 50 Appendix A. Generic GDCs expected to have application for SFRs, lead fast reactors (LFRs), gas-cooled fast reactors (GFRs), high-temperature gas reactors (HTGRs), fluoride high-temperature reactors (FHRs), and molten salt reactors MSRs. Results will be provided to NRC for consideration.
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Regulatory
technology
development
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Evaluate both the NGNP licensing pre-licensing experience and an SFR safety and licensing research plan developed by DOE labs to form the basis and a template for identifying, integrating, and prioritizing approaches for critical research and technology development activities that incorporates licensing considerations that would be applicable to A-SMRs.
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Site screening evaluations
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Identify siting options for SMRs in general and A-SMRs
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Apply geographical information system (GIS) and spatial modeling tools to identify and characterize potential sites for SMRs/A-SMRs in the US using industry-based site screening parameters to evaluate and conduct sensitivity analyses on such key factors as population density, water availability, seismic zones, fault areas, protected lands, proximity to hazardous facilities, environment protection zones (EPZs), etc. Characterize such locations as DOE facilities, Department of Defense facilities, and retired coal plant sites as to their suitability for siting SMRs/A-SMRs.
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SMR site assessment guide
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Develop site hazard assessment guide to support actual site visits and walk downs to inform site suitability evaluators of essential reactor siting criteria and mitigation options that are commonly used by the NRC during license reviews. This development of this guide complements the GIS screening project described above.
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Passive system testing
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Severe accident heat removal testing
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Conduct ex-vessel passive decay heat removal experiments for advanced reactor designs focusing on air-cooled reactor cavity cooling systems to produce data for validation and verification of analysis codes.
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Physical security
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Evaluate and demonstrate potential for reduced staffing
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Development of tools with the following capabilities: use of improved technology to decrease physical security forces, modeling of force-on-force exercises, analyze time sequences of security events, and prioritization of risks to allocate resources to minimize probability of threat.
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Insulated duct (3 inches thick) Down to test section
Roof of Bldg. 308
test section
Pit
ft deep)
Figure 14.4 Severe accident testing facility for passive safety system (3 inches = 75 mm, 24 inches = 600 mm, 20 ft = 6 m).
‘Because many SMRs are still in early developmental stages and the designs are not yet fixed, the designers have a unique opportunity to determine the appropriate design basis threat; develop emergency preparedness; and integrate physical security protection, cyber security protection, and material accountability and control (MC&A) measures with the design and operational requirements during the design process and during the development of a license applicant’s physical security and MC&A programs and systems. Therefore, SMR designers are expected to integrate security into the design and will need to conduct a security assessment to evaluate the level of protection provided, including safeguards aspects of SMR-related fuel cycle and transportation activities.’
The R&D underway is focused on developing an understanding, from an economics standpoint, of some of the key differences between small modular reactors and large LWRs in terms of design (smaller size with passive versus active systems), construction (factory fabrication of modules versus stick built on site), financing costs (lower capital outlay for initial module(s) and deployment of additional modules over time
to meet increasing demand for power), learning rates for factory fabrication going from first-of-a-kind (FOAK) to-nth-of-a-kind (NOAK) production for standardized modules, and potential for reduced staffing levels. The intent is to examine and evaluate these factors for SMRs in general to establish the foundational capability to evaluate costs for SMRs in general and then modify or adapt the models and tools for A-SMRs as these designs evolve and mature in the future.
Current assessment methods related research in these three areas is listed in Table 14.4 including a brief summary of the scope for each research area.
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Table 14.4 Summary of ART assessment methods related R&D projects
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Research areas
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Research scope
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Probabilistic risk assessment
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SMR PRA Framework A-SMRs
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Activities include develop PRA framework to support modeling, phenomena identification/representation, and risk integration, demonstrate capability to model passive system reliability, develop an accident progression plant state database by analyzing a set of advanced liquid metal — cooled reactor (LMR) accidents, and develop enhanced modeling capability by coupling an advanced LMR simulation model (physics) with an advanced PRA model. Other areas addressed have included identifying surrogates for safety goals for non-LWR advanced reactors and identification of initiating events for SFRs and HTGRs
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Safeguards and security
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Adapt proliferation resistance and physical protection (PR&PP) methodologies for A-SMRs
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Assess PR&PP methodologies developed by DOE labs for applicability to A-SMRs examining special features and characteristics of SMRs in general, the interplay and synergy between security and safety, and aspects important to licensing by the NRC.
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Economics
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Model and tools development
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Examine effects of factory fabrication, modular construction; supply chain optimization, FOAK versus NOAK costs, and financing impacts from phased deployment of multiple modules including interactions with SMR industry. Adapt the G4Econ model for estimating costs for A-SMRS as developed by the Generation IV International Forum (GIF).
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Evaluate economics competitiveness
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Develop analysis data and tools to facilitate analysis of economics and competitiveness of various advanced reactor designs with commercial potential including development of a potential business case and market conditions favoring deploying advanced reactor design.
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