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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Development of the Licensing Procedure and Regulatory Framework for the Spent Fuel Storage facility in Korea - 16423

The Public Engagement Commission on SNF management (PECOS) published the recommendation report on the spent fuel management of Korea in June, 2015. Based on this report, the future national policy for spent fuel management of Korea has been established, taking into consideration the national/international trends on policy and technology development. Regardless of the recommendation report of PECOS, Spent fuel storage casks are necessary in Korea. Therefore, various types of spent fuel storage casks are now being developed by Korea vendors. For example, Concrete storage casks and dual purpose metal casks are now under development by the KORAD (Korea Radioactive waste agency) for future use in the interim storage facility. Unfortunately, there is no independent licensing procedure for spent fuel storage casks in Nuclear Safety Act (NSA) because is the casks are considered an integral part of the interim storage facility safety equipment. Furthermore, the definition of radioactive waste in the NSA was changed recently. Now, spent fuel is separated from the definition of 'radioactive waste'. Spent fuel can only become radioactive waste by the decision through the meeting of the relative ministers of Korea government. For that reason, the licensing procedure for interim spent fuel storage facilities was separated from the current 'disposal facility, etc.' in accordance with the article 63 of NSA. The aim of this study is to develop the licensing procedure for the storage cask, and also to develop a revised draft of interim storage facility procedure within the NSA. Once this independent licensing procedure on the spent fuel storage cask is introduced to the NSA, it is expected that developers or operators can develop and commercialize the storage cask in Korea. In this study, an independent licensing procedure for the spent fuel storage facility was developed including the storage cask licensing procedure for the NSA. The procedure was composed of the permit for construction and operation of interim storage facility, criteria for permit, inspection criteria, periodic safety review, and decommissioning criteria, etc. The detailed contents of these requirements were also developed to introduce the regulatory framework for the interim storage facility. Particularly, periodic safety review and decommissioning criteria were developed in accordance with the recommendation of IRRS (International Regulatory Review Service) of IAEA. The developed licensing procedure for spent fuel storage facility will be introduced in NSA in response to the revised definition of NSA and the recommendation report of PECOS. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2014

Improving the effectiveness of impact assessment pertaining to Indigenous peoples in the Brazilian environmental licensing procedure

The number of environmental licence applications for projects affecting Indigenous peoples in Brazil has increased since the implementation of a major infrastructure program (Programa de Aceleração do Crescimento) in 2007. This increase has caused problems for Brazilian agencies involved in environmental licensing procedures (IBAMA, FUNAI and others). We analyze the Brazilian environmental licensing procedure for situations involving Indigenous peoples, Maroons (Quilombolas) or other traditional communities in order to identify potential improvements for Brazil and potentially other countries. Although Brazilian procedures are consistent with international best practice in environmental licensing, in practice social impacts are inadequately addressed, mitigation measures are poorly implemented, and there is a lack of enforcement and compliance. The paper is based on document analysis and interviews with key actors in governmental and non-governmental organizations and Indigenous leaders. We suggest that Free, Prior and Informed Consent (FPIC) processes need to be conducted at the earliest stages of project planning, and that Indigenous peoples should actively participate in impact assessment, monitoring and evaluation processes. In order to achieve a social licence to operate, there needs to be full recognition of traditional knowledge and acceptance of Indigenous values and concepts. We also recommend increased involvement of social experts and mediators as well as improved accountability, enforcement and grievance mechanisms in the licensing process. - Highlights: • The Brazilian environmental licensing system needs to address social impacts better. • Communities need to be consulted at the earliest stage possible. • Indigenous peoples need to be invited to participate in impact assessment teams. • Independent Indigenous committees to monitor implementation of mitigation measures. • Accountability, enforcement and grievance mechanisms need to be improved.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Developments in the Regulatory Framework of Nuclear Waste Management in Germany - Licensing Procedures for storage of SNF and Public Involvement - 19612

According to article 6 of the German Atomic Energy Act (AtG), storage of Spent Nuclear Fuel requires a license. The competent licensing authority in this field is the Federal Office for Safety of Nuclear Waste Management (BfE). According to the Act for selecting a repository site for heat-generating radioactive waste (HAW) (Site Selection Act - StandAG) dating from 2017, BfE has been assigned the task of developing, conducting, and evaluating public participation procedures in the process of site search and selection for a deep geological repository for radioactive waste and SNF. Article 6 AtG applies to interim storage of SNF. If the legally defined licensing conditions by article 6 (2) AtG are met, the storage license applied for has to be granted. For on-site facilities, interim storage has been limited to 40 years. The licensing procedures for interim storage of SNF are carried out in accordance with the general administrative procedural rules. In certain cases due to the Environmental Impact Assessment Act (EIA Act), an EIA has to be carried out. In these cases, a formalized licensing procedure including an involvement of the public is conducted. The Nuclear Licensing Procedure Ordinance (AtVfV) originating from 1977 and reformulated in 1995 defines formalized rules for the public participation procedure which have to be followed strictly. These include a public hearing. The risen objections are evaluated by the licensing authority and taken account of in the licensing decision. The process of repository site selection defined by the StandAG exceeds these formalized procedures significantly: The objective of this process is to achieve a broad social consensus about the site selection procedure and about a repository site that will offer the best possible safety for one million years. Therefore, the process has to be particularly transparent, and involvement of the public - including newly developed forms of public involvement - is an essential part of it. BfE as competent authority in both the fields of repository site search and selection and licensing of interim storage of SNF has recently developed new strategies of involving the public concerning interim storage of SNF. Supplementing the standard licensing procedures, BfE presently informs and involves the public about topical issues regarding the present state and recent developments in the field of interim storage of SNF. Current central topics are for example the return of HAW and MAW from reprocessing of SNF in France and UK as well as perspective longer interim storage periods on the interface with final disposal. Regarding longer interim storage, host communities of interim storage facilities are concerned that interim storage might be extended indefinitely. Additionally, there is a strong fear of transports of radioactive waste and SNF from one place to another. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

The Construction of the Konrad Repository - Status and Perspective - 13034

Due to the Atomic Energy Act of Germany the Federation is responsible for the construction and operation of installations for the safekeeping and disposal of radioactive waste. The Federal Office for Radiation Protection (Bundesamt fuer Strahlenschutz - BfS) is assigned with this duty. In 1982 the abandoned iron ore mine Konrad near Salzgitter (Federal State of Lower Saxony) was proposed as a repository for low and intermediate level radioactive waste with negligible heat generation. After 20 years of plan approval procedure the license was granted by the Ministry for Environment of Lower Saxony in May 2002. This decision was finally confirmed by the Federal Administrative Court in March 2007. The construction has started, but former assumptions about the beginning of waste emplacement tuned out to be too optimistic. In the course of the preparatory work and the implementation planning it turned out that many changes need to be done. As a matter of fact most of the documents and planning originate from the 1990's and need to be revised because from that time on until now no adaptation was appropriate. The necessity to apply the state-of-the-art technology and other legal implications give rise to further changes and new licensing procedures, especially building licenses. Furthermore, the license from 2002 also includes a lot of collateral clauses that need to be fulfilled before radioactive waste can be emplaced. With this in mind, the time frame for the construction of the Konrad repository was revised in 2010. As a result, the completion of the erection before 2019 does not seem to be realistic. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Development blind spots and environmental impact assessment: Tensions between policy, law and practice in Brazil's Xingu river basin

This paper explores the tensions involved in Environmental Impact Assessments (EIAs) and environmental licensing through a detailed analysis of the legal disputes and public contestations surrounding two projects, a large hydroelectric dam and a gold mine, which are proximately located to each other. Broadly, we argue that EIAs may function to reinforce rather than genuinely inform or potentially resist prevailing developmental logics. The research extends David Mosse's argument that development self-perpetuates “success” through participation and procedural licensing mechanisms while on-the-ground realities diverge significantly. It offers a critical examination of EIA utility and processes through identifying three general mechanisms within EIA and environmental licensing procedures that contribute to approval of projects and promote a perception of their legitimacy, while detracting from the intended purposes of EIAs as opportunities for meaningful public discussion and sustainability-oriented decision making. These mechanisms include discourses that entrench project necessity and make them appear inevitable, public participation, and the isolated treatment of related projects. This work situates an understanding of particular EIAs within a deeper process of regional territorial development and resource extraction.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

HAZARD ANALYSIS OF DIGITAL ENGINEERED SAFETY FEATURES ACTUATION SYSTEM IN ADVANCED NUCLEAR POWER PLANTS USING A REDUNDANCY-GUIDED APPROACH

Replacing the existing aging analog instrumentation and control (I&C) systems with modern safety control and protection digital technology offers one of the foremost means of performance improvements and cost reductions for the existing nuclear power plants (NPPs). However, the qualification of digital I&C systems remains a challenge, especially considering the issue of software common-cause failures (CCFs), which are difficult to address. With the application and upgrades of advanced digital I&C systems, software CCFs have become a potential threat to plant safety because most redundant designs use similar digital platforms or software in the operating and application systems. With complex designs of multilayer redundancy to meet the single-failure criterion, digital I&C safety systems (e.g., engineered safety-features actuation system [ESFAS]) are of a particular concern in the U.S. Nuclear Regulatory Commission (NRC) licensing procedures. This paper applies a modularized approach to conduct redundancy-guided systems-theoretic hazard analysis for an advanced digital ESFAS with multilevel redundancy designs. Systematic methods and risk-informed tools are incorporated to address both hardware and software CCFs, which provide guidance to eliminate the triggers of potential single points of failure in the design of digital safety systems in advanced plant designs.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Seven good practices for the environmental licensing of coastal interventions: Lessons from the Italian, Cuban, Spanish and Colombian regulatory frameworks and insights on coastal processes

Highlights: • Environmental licensing procedures (ELP) line up by projects instead of environments. • The ELP of four countries was compared according to the generic EIA stages. • The study relies upon the revision of EIA legislation and technical guidelines. • Seven EIA good practices were extracted from the ELP analysis of the four countries. • A changing approach is proposed for the EPL performance on coastal interventions. - Abstract: Environmental licensing is the regulatory procedure that enforces the environmental impact assessment (EIA) of human activities inside a given country. Despite worldwide acceptance of EIA as a valid tool, its application in coastal environments is still too diverse and limited regarding the specificity of the natural processes influencing the shore. This paper compares the Environmental Licensing Procedure (ELP) of four countries, focusing on the activities that could affect the coastal geomorphology. The acquisition and validation of information were done through interviews with EIA representatives in each country, who signalized the official documents of environmental licensing and coastal management to be considered in the documentary review. The results present those differences and similarities among ELP stages in each country, based on the principles of the International Association of Impact Assessment and the national documents analyzed. In sum, 59 interventions associated with human uses and activities in the coastal zone were compared according to the prescriptive character of the environmental licensing in Italy, Spain, Cuba and Colombia. The natural processes influencing coastal geomorphology were also analyzed within the technical criteria included in the official guidelines for the EIA, finding a generalized weakness in processes associated with geochemical courses on coastal environments. By way of discussion, seven good practices are illustrated, according to their pertinence to the impact assessment of the coastal zone: 1) The integration of screening and scoping; 2) Evaluation focusing on the environment rather than the intervention; 3) Binding the coastal zone delimitation; 4) Institutional articulation; 5) Accreditation of environmental consultancies; 6) Official guidelines by types of environment; 7) The integration of environmental geographic information. Finally, general conclusions to assist EIA practitioners operating in the four countries and recommendations to lead further research are provided, introducing a novel process-oriented approach for ELP.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

U.S. Nuclear Regulatory Commission Historical Perspectives of Very Low-Level Radioactive Waste - 18367

The United States Nuclear Regulatory Commission (NRC), in Title 10 of the Code of Federal Regulations Part 61 (10 CFR Part 61), 'Licensing Requirements for Land Disposal of Radioactive Waste', provides licensing procedures, performance objectives, and technical requirements for the issuance of licenses for the land disposal of low-level radioactive waste. Low-level radioactive waste is divided into four categories based on its potential risk and need for isolation. Class A is the lowest category of low-level radioactive waste and poses the least risk. A large percentage of Class A low-level waste contains very low radionuclide concentrations and does not pose a significant health and safety risk. In the current regulatory framework, this waste, referred to as low-activity or very low-level waste, is managed in the same manner as much more hazardous waste. In 1986 and 1990, as a result of the Low-Level Radioactive Waste Policy Amendments Act of 1985, the NRC issued the Below Regulatory Concern (BRC) policy statement. This policy statement established an implementation plan regarding the expeditious handling of rulemaking petitions 'to exempt specific radioactive waste streams from regulation due to the presence of radionuclides in sufficiently low concentrations or quantities as to be below regulatory concern.' The BRC policy statement provided a consistent risk framework when considering regulatory exemption decisions, such as: (1) the release for unrestricted public use of lands and structures containing residual radioactivity; (2) the distribution of consumer products containing small amounts of radioactive material; (3) the disposal of very low-level radioactive waste at other than licensed disposal sites; and (4) the recycling of slightly contaminated equipment and materials. Due to concerns with the BRC policy that were raised by Congress, the States, the public, and others, Congress enacted the Energy Policy Act of 1992, which revoked the NRC's 1986 and 1990 BRC policy statements and led to the NRC's formal withdrawal of the BRC policy in 1993. Stakeholders raised concerns on NRC's potential deregulation of radioactive material. Additionally, in March 2005, the NRC staff proposed a rule to amend 10 CFR Part 20, 'Standards for Protection Against Radiation,' to include radiological criteria for controlling the disposition of solid materials with very small amounts of residual radioactivity. The NRC staff also proposed a limited disposition approach for the disposition of solid material, limiting the release of solid material meeting a 0.01 milli-Sievert per year (mSv/yr) [1 milli-rem (mrem/yr)] dose criterion, from licensed control. In June 2005, the Commission disapproved publication of the proposed rule and deferred the rulemaking until a later time, stating that the NRC's existing approach of reviewing specific cases on an individual basis was fully protective of public health and safety. This rulemaking effort was discontinued by the Commission in 2016. Recently, several nuclear power plant licensees have announced early decommissioning of their facilities. Some stakeholders have expressed concerns about the capacity and disposal costs associated with using the four existing low-level waste disposal sites for very low levels of radioactive waste (i.e., waste at the low end of the Class A category). A more risk-informed, performance based approach to waste disposal would allow more flexibility in managing this waste commensurate with its risk and hazard. A new approach would also allow the NRC to align with international standards for this type of waste. The NRC is presently conducting a scoping study to identify the actions the agency should take to strengthen its regulatory framework for very low-level waste disposal. The Very Low-Level Waste (VLLW) scoping study will consider divergent stakeholder comments; lessons learned from the BRC policy statements and the proposed rule on radiological criteria for controlling the disposition of solid materials; and best practices of other countries with respect to VLLW disposal. The NRC will also engage other government agencies to discuss regulatory options for VLLW. This paper offers a historical overview of past NRC initiatives to manage the lower end of Class A waste in a manner that is risk informed and performance based. It examines previous endeavors and discusses the regulatory challenges that arose. It also addresses lessons learned and introduces NRC's current effort regarding very low-level radioactive waste disposal. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

New container development for the international market - 15656

Designs of casks and containers for the disposal of radioactive waste have to meet safety requirements for transport and storage. Since nuclear law is a national issue, the legal specifications often differ significantly. To improve the flexibility of a given basic design, the development of a set of generic design elements and the application of favorable material characteristics are of major importance. As an example for the international approach the design development for an IP-2 container for radioactive non-fuel waste made of Ductile Cast Iron (DCI) for the UK market in the frame of the specific national waste disposal concept is described. The results of drop tests performed during the licensing procedure and of parametric analysis work regarding a wide spectrum of accidental scenarios and impacts show the excellent behavior of the container concept and confirm the related favorable manufacturing procedures. Furthermore, the development work provided a significant set of proposals for the future detailed work. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2011

Nuclear Energy – Knowledge Base for Advanced Modeling and Simulation (NE-KAMS) Code Verification and Validation Data Standards and Requirements: Fluid Dynamics Version 1.0

V&V and UQ are the primary means to assess the accuracy and reliability of M&S and, hence, to establish confidence in M&S. Though other industries are establishing standards and requirements for the performance of V&V and UQ, at present, the nuclear industry has not established such standards or requirements. However, the nuclear industry is beginning to recognize that such standards are needed and that the resources needed to support V&V and UQ will be very significant. In fact, no single organization has sufficient resources or expertise required to organize, conduct and maintain a comprehensive V&V and UQ program. What is needed is a systematic and standardized approach to establish and provide V&V and UQ resources at a national or even international level, with a consortium of partners from government, academia and industry. Specifically, what is needed is a structured and cost-effective knowledge base that collects, evaluates and stores verification and validation data, and shows how it can be used to perform V&V and UQ, leveraging collaboration and sharing of resources to support existing engineering and licensing procedures as well as science-based V&V and UQ processes. The Nuclear Energy Knowledge base for Advanced Modeling and Simulation (NE-KAMS) is being developed at the Idaho National Laboratory in conjunction with Bettis Laboratory, Sandia National Laboratories, Argonne National Laboratory, Utah State University and others with the objective of establishing a comprehensive and web-accessible knowledge base to provide V&V and UQ resources for M&S for nuclear reactor design, analysis and licensing. The knowledge base will serve as an important resource for technical exchange and collaboration that will enable credible and reliable computational models and simulations for application to nuclear power. NE-KAMS will serve as a valuable resource for the nuclear industry, academia, the national laboratories, the U.S. Nuclear Regulatory Commission (NRC) and the public and will help ensure the safe, economical and reliable operation of existing and future nuclear reactors.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2012

Development of integrated core disruptive accident analysis code for FBR - ASTERIA-FBR

The evaluation of consequence at the severe accident is the most important as a safety licensing issue for the reactor core of liquid metal cooled fast breeder reactor (LMFBR), since the LMFBR core is not in an optimum condition from the viewpoint of reactivity. This characteristics might induce a super-prompt criticality due to the core geometry change during the core disruptive accident (CDA). The previous CDA analysis codes have been modeled in plural phases dependent on the mechanism driving a super-prompt criticality. Then, the following event is calculated by connecting different codes. This scheme, however, should introduce uncertainty and/or arbitrary to calculation results. To resolve the issues and obtain the consistent calculation results without arbitrary, JNES is developing the ASTERIA-FBR code for the purpose of providing the cross-check analysis code, which is another required scheme to confirm the validity of the evaluation results prepared by applicants, in the safety licensing procedure of the planned high performance core of Monju. ASTERIA-FBR consists of the three major calculation modules, CONCORD, dynamic-GMVP, and FEMAXI-FBR. CONCORD is a three-dimensional thermal-hydraulics calculation module with multi-phase, multi-component, and multi-velocity field model. Dynamic-GMVP is a space-time neutronics calculation module. FEMAXI-FBR calculates the fuel pellet deformation behavior and fuel pin failure behavior. This paper describes the needs of ASTERIA-FBR development, major module outlines, and the model validation status. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2017

Activation Calculation for the Dismantling and Decommissioning of a Light Water Reactor Using MCNP{sup TM} with ADVANTG and ORIGEN-S

The boiling water reactor (BWR) Philippsburg 1 (KKP1) and the pressurized water reactor (PWR) Neckarwestheim 1 (GKN I), with a thermal power of 2575 MW{sub th} resp. 2497 MW{sub th}, were shut down and entered directly the post-operational phase which is covered by the operating license held by the nuclear power plant owner. The decommissioning of a nuclear power plant (NPP) which is licensed under chap. 7 of the German Atomic Energy Act, following the post-operational phase requires a comprehensive licensing procedure including in particular radiation protection aspects and possible impacts to the environment. Decommissioning requires a decommissioning license. This will include essential changes in requirements for the systems and components and will mainly lead to the immediate dismantling of the nuclear power plant which is now the only permitted decommissioning strategy in Germany. In this context, neutron activation calculations for the structural components of KKP1 and GKN I have to be carried out to predict occurring activities and to estimate future costs for conditioning and packaging. To avoid an overestimation of the radioactive inventory and to calculate the expenses for decommissioning as accurate as possible, modern state-of-the-art Monte-Carlo-Techniques (MCNP6) combined with automated variance reduction tools (ADAVANTG) are used and are coupled with the activation and decay module ORIGEN-S. This paper presents the calculation procedure and the obtained results with a validation by measured activations and gamma dose rates.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Experience by BAM in the Transport Package Safety Assessment of German Waste Containers - 18469

Transport and storage containers for low and mid-level radioactive waste are getting more and more of relevance due to the nuclear phase out decision in 2011. For higher activities Type B(U) approved waste containers will be needed for the shut down and dismantling phases of NPPs. It is expected that large quantities are required in the near future. German waste containers are generally approved for transport and interim storage and are also intended for the final disposal in the Konrad repository. BAM is involved in the authority licensing of transport package designs in Germany. In this context, BAM is responsible for the assessment of safe containment, mechanical, thermal and quality management issues. BAM also operates test facilities and performs drop as well as thermal tests during package licensing procedures. This paper summarizes our experience in the transport package design assessment of Type B(U) waste containers. A general overview of the approval process, the requirements and approaches BAM applies are described. Some examples are used to illustrate different aspects and technical issues we are addressing during the package assessment. In the first part of the paper the specific design aspects of German waste containers are described. Here, a general overview is given e.g. about closure systems, impact limiter designs, and the handling concepts. Furthermore, the wide range of radioactive content and their physical behavior including the impact on the packages assessment are described. The second part is focused on questions about the licensing and assessment process of German waste containers from the BAM authority point of view. The general approaches for the strategy of demonstration are outlined on the basis of the test conditions according to IAEA Regulations SSR-6. Furthermore, particular issues of the mechanical and thermal assessment with respect to the specific test conditions are discussed. For accident conditions of transport, aspects to be mentioned are e.g. the assessment of the lid bolts, the axial gap applied between content and lid, and the thermal behavior of the wood filled impact limiter after the fire test. However, issues of the assessment for routine and normal conditions of transport are addressed in this paper, too. The intention of this paper is introduce recent approval procedure experience in Germany, describing technical evaluation issues and so reduce rounds of questions during applications. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

FERC Hydropower Licensing: A Review of Utilization of the ILP, TLP, and ALP

A preliminary consideration for license applicants seeking to develop non-federal hydropower projects includes determining whether the Federal Energy Regulatory Commission (FERC) has authority over the development, and if so, what licensing procedures are required or may be an option for authorizing the project. Projects subject to FERC jurisdiction, which do not meet the qualification requirements for an exemption from FERC hydropower licensing, must complete the FERC hydropower licensing process utilizing one of FERC's three licensing processes: The Integrated Licensing Process (ILP), Traditional Licensing Process (TLP), or Alternative Licensing Process (ALP). Effective after July 23, 2005, the ILP became the default hydropower licensing process under the FPA [18 CFR Section 5.3(a)(2)] and any license applicant seeking to use the TLP or ALP is now required to submit to FERC a request to use the TLP or ALP with their Notice of Intent (NOI) and Pre-Application Document (PAD) and receive approval before initiating either of those processes.

13 HYDRO ENERGY↗
DOE OSTI2022

An Integrated Risk Assessment Process of Safety-Related Digital I&C Systems in Nuclear Power Plants

Upgrading the existing analog instrumentation and control (I&C) systems to state-of-the-art digital I&C (DI&C) systems will greatly benefit existing light water reactors. However, the issue of software common cause failure (CCF) remains an obstacle in terms of qualification for digital technologies. Existing analyses of CCFs in I&C systems mainly focus on hardware failures. With the application and upgrading of new DI&C systems, design flaws could cause software CCFs to become a potential threat to plant safety, considering that most redundancy designs use similar digital platforms or software in their operating and application systems. With complex multilayer redundancy designs to meet the single failure criterion, these I&C safety systems are of particular concern in U.S. Nuclear Regulatory Commission licensing procedures. In Fiscal Year 2019, the Risk-Informed Systems Analysis (RISA) Pathway of the U.S. Department of Energy’s Light Water Reactor Sustainability Program initiated a project to develop a risk assessment strategy for delivering a strong technical basis to support effective, licensable, and secure DI&C technologies for digital upgrades and designs. An integrated risk assessment for the DI&C process was proposed for this strategy to identify potential key digital-induced failures, implement reliability analyses of related digital safety I&C systems, and evaluate the unanalyzed sequences introduced by these failures (particularly software CCFs) at the plant level. Here this paper summarizes these RISA efforts in the risk analysis of safety-related DI&C systems at Idaho National Laboratory.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2021

INTEGRATED RISK ASSESSMENT OF DIGITAL I&C SAFETY SYSTEMS FOR NUCLEAR POWER PLANTS

Upgrading the existing analog instrumentation and control (I&C) systems to state-of-the-art digital I&C (DI&C) systems provides the foremost means to improve performance and reduce costs for existing light-water reactors (LWRs). However, qualification of digital technologies remains a challenge?especially the issue of software common cause failure (CCF), which has been difficult to address. Existing analyses of CCFs in I&C systems mainly focus on hardware failures. With the application and upgrading of new DI&C systems, software CCFs due to design flaws might become a potential threat to plant safety, considering that most redundancy designs use similar digital platforms or software in their operating and application systems. With complex multi-layer redundancy designs to meet the single failure criterion, these I&C safety systems are of particular concern in U.S. Nuclear Regulatory Commission (NRC) licensing procedures. In 2019, the Risk-Informed Systems Analysis (RISA) Pathway of the U.S. Department of Energy?s (DOE?s) Light Water Reactor Sustainability (LWRS) Program initiated a project to develop a risk assessment strategy for delivering a strong technical basis to support effective, licensable, secure DI&C technologies for digital upgrades/designs. An integrated risk assessment for the DI&C (RADIC) process was proposed for this strategy to identify potential key digital-induced failures, implement reliability analyses of related digital safety I&C systems, and evaluate the unanalyzed sequences introduced by these failures (particularly software CCFs) at the plant level. This paper summarizes these RISA efforts in the risk analysis of safety-related DI& systems at Idaho National Laboratory.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2019

An Integrated Risk Assessment Process for Digital Instrumentation and Control Upgrades of Nuclear Power Plants

Most of the existing nuclear power plants (NPPs) in the world rely on traditional analog instrumentation and control (I&C) systems for monitoring, control, and protection functions. With the industrial base largely moving to digital systems, the operation and maintenance of plants involves managing issues including lack of needed analog spare parts, increasing maintenance costs, and the loss of vendor support. Compared with existing analog I&C systems, digital I&C systems have significant functional advantages, such as reliable system performance in terms of accuracy and computational capability, high data handling and storage capabilities to fully measure and display operating conditions, and improved capabilities (e.g., fault tolerance, self-testing, signal validation, process system diagnostics). Therefore, the U.S. nuclear power industry has initiated the replacement of existing, aging analog systems with digital I&C technology, and is developing new designs for advanced plants using digital systems in integrated control rooms to provide modern control and protection systems. However, the qualification of digital I&C systems remains a challenge, especially the issue of software common cause failure (CCF), which has been difficult to address. A CCF is the malfunction of two or more plant components or functions due to a single failure source. CCFs have the potential to generate unanalyzed events or sequences that may not be bounded by previous plant accident analyses, therefore, to challenge the plant safety. Existing analyses on CCF in I&C systems are mainly focusing on hardware failures. With the application and upgrades of new digital I&C systems, software CCFs due to design flaws have become a potential threat to plant safety considering most redundancy designs are using the similar digital platforms or software in the operating and application systems. With complex multi-layer redundancy designs to meet the single failure criterion, these I&C safety systems are of a particular concern in the U.S. Nuclear Regulatory Commission (NRC) licensing procedures. Therefore, there is a need to develop an integrated risk assessment strategy with digital CCF and plant transient responses considered to assure the long-term safety and reliability of vital digital systems and reduce uncertainties in costs, time, and support integration of digital systems in the plant. The overall goal of this project is to deliver a strong technical basis to support effective, licensable, and secure digital I&C technologies for the digital upgrades to existing NPPs. To deal with the expensive licensing justifications from regulatory insights, this technical basis is instructive for nuclear vendors and utilities to effectively lower the costs associated with digital compliance and speed-up industry advances by: (1) defining an integrated risk-informed analysis process for digital I&C upgrades including hazard analysis, reliability analysis, and consequence analysis; (2) applying systematic and risk-informed tools to address CCFs and quantify responding failure probabilities for digital I&C technologies; (3) evaluating the impact of digital failures at the individual level, system level, and plant level; and (4) providing insights and suggestions on designs to manage the risks, thus to support the development, licensing, and deployment of advanced digital I&C technologies on NPPs. Upgrading digital I&C (safety and non-safety related) systems in existing NPPs within a cost-effective and regulatory acceptable way offers the foremost means of performance improvements and cost-reductions for existing NPPs. One key outcome of this project is to perform plant-specific risk assessment to provide a sustainable scientific support for enabling industry to balance the digital-related risks, costs, reliability, and safety.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Hazard analysis for identifying common cause failures of digital safety systems using a redundancy-guided systems-theoretic approach

Replacing the existing aging analog instrumentation and control (I&C) systems with modern safety control and protection, digital technology offers one of the foremost means of performance improvements and cost reductions for the existing nuclear power plants (NPPs). However, the qualification of digital I&C systems remains a challenge, especially considering the issue of software common-cause failures (CCFs), which are difficult to address. With the application and upgrades of advanced digital I&C systems, software CCFs have become a potential threat to plant safety because most redundant designs use similar digital platforms or software in the operating and application systems. With complex designs of multilayer redundancy to meet the single-failure criterion, digital I&C safety systems (e.g., engineered safety-features actuation system [ESFAS]) are of a particular concern in the U.S. Nuclear Regulatory Commission (NRC) licensing procedures. Here, this paper applies a modularized approach to conduct redundancy-guided systems-theoretic hazard analysis for an advanced digital ESFAS with multilevel redundancy designs. Systematic methods and risk-informed tools are incorporated to address both hardware and software CCFs, which provide guidance to eliminate the causal factors of potential single points of failure in the design of digital safety systems in advanced plant designs.

42 ENGINEERING↗