Historical Perspectives and Insights on ACRS Review of AP1000 Design Certification

Author(s):  
Hossein Nourbakhsh ◽  
Weidong Wang ◽  
Harold Ray ◽  
Thomas Kress

The U.S. Nuclear Regulatory Commission (NRC) requires that each application for a standard design certification be referred to the Advisory Committee on Reactor Safeguards (ACRS) for a review and report on those portions of the application which concern safety. This paper begins with perspectives on the role of the ACRS in the design certification review process. It then summarizes the ACRS observations and recommendations made in the Committee’s reports during the AP1000 design certification reviews to date.

Author(s):  
Wendy J. Reece ◽  
Susan G. Hill

A set of radiation overexposure event reports were reviewed as part of a program to examine human performance in industrial radiography for the U.S. Nuclear Regulatory Commission. Incident records for a seven year period were retrieved from an event database. Ninety-five exposure events were initially categorized and sorted for further analysis. Descriptive models were applied to a subset of severe overexposure events. Modeling included: (1) operational sequence tables to outline the key human actions and interactions with equipment, (2) human reliability event trees, (3) an application of an information processing failures model, and (4) an extrapolated use of the error influences and effects diagram. Results of the modeling analyses provided insights into the industrial radiography task and suggested areas for further action and study to decrease overexposures.


Author(s):  
Jeffrey G. Arbital ◽  
Dean R. Tousley ◽  
James C. Anderson

The National Nuclear Security Administration (NNSA) is shipping bulk quantities of fissile materials for disposition purposes, primarily highly enriched uranium (HEU), over the next 15 to 20 years. The U.S. Department of Transportation (DOT) specification 6M container has been the workhorse for NNSA and many other shippers of radioactive material. However, the 6M does not conform to the safety requirements in the Code of Federal Regulations (10 CFR 71[1]) and, for that reason, is being phased out for use in the secure transportation system of the U.S. Department of Energy (DOE) in early 2006. BWXT Y-12 is currently developing the replacement for the DOT 6M container for NNSA and other users. The new package is based on state-of-the-art, proven, and patented technologies that have been successfully applied in the design of other packages. The new package will have a 50% greater capacity for HEU than the 6M, and it will be easier to use with a state-of-the-art closure system on the containment vessel. This new package is extremely important to the future of fissile, radioactive material transportation. An application for license was submitted to the U.S. Nuclear Regulatory Commission (NRC) in February 2005. This paper reviews the license submittal, the licensing process, and the proposed contents of this new state-of-the-art shipping container.


Author(s):  
Russell Wagner

The U.S. Nuclear Regulatory Commission (NRC) has provided set guidance that hydrogen concentrations in radioactive material packages be limited to 5 vol% unless the package is designed to withstand a bounding hydrogen deflagration or detonation. The NRC guidance further specifies that the expected shipping time for a package be limited to one-half the time to reach 5 vol% hydrogen. This guidance has presented logistical problems for transport of retrieved legacy waste packages on the Department of Energy (DOE) Hanford Site that frequently contain greater than 5 vol% hydrogen due to their age and the lack of venting requirements at the time they were generated. Such packages do not meet the performance-based criteria for Type B packaging, and are considered risk-based packages. Duratek Technical Services (Duratek) has researched the true risk of hydrogen deflagration and detonation with closed packages, and has developed technical justification for elevated concentration limits of up to 15 vol% hydrogen in risk-based packages when transport is limited to the confines of the Hanford Site. Duratek has presented elevated hydrogen limit justification to the DOE Richland Operations Office and is awaiting approval for incorporation into the Hanford Site Transportation Safety Document. This paper details the technical justification methodology for the elevated hydrogen limits.


Author(s):  
Ikbal Lebbi ◽  
Javad Moslemian

During U.S. Nuclear Regulatory Commission (NRC) reviews of Design Certifications (DC) and Combined License (COL) applications, the NRC staff identified several technical issues related to seismic analysis and structural design of the containment and other seismic Category I structures and foundations. These technical issues resulted in a need of improved technical guidance to facilitate reviews of future DC and COL applications. NUREG-0800, “Standard Review Plan (SRP)”, Sections 3.7 and 3.8 provide guidance related to the review of seismic analysis and structural design. NUREG-0800 SRP Sections 3.7 and 3.8 have been revised recently in an effort to enhance NRC staff guidance for the review of future DC and COL applications. SRP Sections 3.7 and 3.8 have not been revised since 2007. Recent revisions of these Sections have been completed in 2013, except for SRP 3.7.1, only a “DRAFT” revision was completed in 2013. The objective of this paper is to briefly describe the important technical issues that presented technical challenges to the applicants during the NRC staff review process of DC and COL applications, and the proposed enhancements to the specific Sections of SRP 3.7 and 3.8. The paper presents complete details of the recent revisions of NUREG-0800 SRP Sections 3.7.1, 3.7.2, 3.7.3, 3.8.1, 3.8.3, 3.8.4, and 3.8.5.


Author(s):  
Jerry McNeish ◽  
Peter Swift ◽  
Rob Howard ◽  
David Sevougian ◽  
Donald Kalinich ◽  
...  

The development of a deep geologic repository system in the United States has progressed to the preparation of an application for a license from the U.S. Nuclear Regulatory Commission. The project received site recommendation approval from the U.S. President in early 2002. The next phase of the project involves development of the license application (LA) utilizing the vast body of information accumulated in study of the site at Yucca Mountain, Nevada. Development of the license application involves analyses of the total system performance assessment (TSPA) of the repository, the TSPA-LA. The TSPA includes the available relevant information and model analyses from the various components of the system (e.g., unsaturated geologic zone, engineered system (waste packaging and drift design), and saturated geologic zone) (see Fig. 1 for nominal condition components), and unites that information into a single computer model used for evaluating the potential future performance or degradation of the repository system. The primary regulatory guidance for the repository system is found in 10 CFR 63, which indicates the acceptable risk to future populations from the repository system. The performance analysis must be traceable and transparent, with a defensible basis. The TSPA-LA is being developed utilizing state-of-the-art modeling software and visualization techniques, building on a decade of experience with such analyses. The documentation of the model and the analyses will be developed with transparency and traceability concepts to provide an integrated package for reviewers. The analysis relies on 1000’s of pages of supporting information, and multiple software and process model analyses. The computational environment represents the significant advances in the last 10 years in computer workstations. The overall approach will provide a thorough, transparent compliance analysis for consideration by the U.S. Nuclear Regulatory Commission in evaluating the Yucca Mountain repository.


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