Session: CS-07-04 The Warren H. Bamford Memorial Symposium on Recent Developments in ASME Codes and Standards-4

Paper Number: 155535

155535 - Technical Basis for Asme Section Iii Code Case N-940 

Abstract: 

Advanced reactor designers are considering probabilistic safety and risk in the plant design, which is a paradigm shift and a significantly different safety basis compared to light-water reactors which used a deterministic safety classification process.  Safety and risk significance categorization processes such as NEI 18-04 (Licensing Modernization Program) recognize this paradigm shift and are endorsed by the US regulator.  These processes generally permit construction of items with minimal contribution to safety or risk (e.g., non-safety related with special treatment (NSRST)) to industrial codes with appropriate special treatments. 

 

Several advanced reactor designers are considering the use of industrial codes for these items to improve commercial viability due to perceived advantages of the cost and schedule of construction.  However, there are reasons why a designer may prefer using nuclear Codes and Standards, such as ASME Section III, for this scope: desirable nuclear design rules, service levels, and quality processes.  Traditionally there are no means by which to use the advantageous nuclear rules without also using rules that might not be commensurate with the item’s contribution to safety or risk.  This paper presents the technical basis for the recently approved Code Case N-940, “Alternate Rules for Nondestructive Examination and Testing of Items Commensurate with their Contribution to Safety or Risk, Section III, Division 5.” 

 

The approach for this Code Case is to use “nuclear design and fabrication” rules with alternate requirements for non-destructive examination (NDE) and testing which are consistent with requirements used in comparable industrial codes and/or in Section XI.  This approach maintains the nuclear design and fabrication expertise gained over the past 60-years of constructing nuclear plants to ASME Section III while reducing commercial risk for construction of items with minimal contributions to safety or risk.  The technical basis for this approach reviews the existing regulatory framework, requirements permitted in industrial codes, and the relationship between Service Levels in the Section III design rules and the associated construction rules (i.e., NDE, materials, and nuclear quality assurance).

Presenting Author: Rachel Romano MPR Associates, Inc.

Presenting Author Biography: Rachel Romano is an experienced engineer at MPR Associates, Inc., where she has engaged clients on a variety of projects in both commercial operating nuclear and advanced nuclear. Her diverse background includes project management, codes and standards development, thermal hydraulic and fluid flow analyses, mechanical design, and fabrication and testing oversight. Rachel’s technical background and leadership earned her the role of Secretary of the ASME BPVC Section III Task Group on Alternate Requirements, while also supporting the Section III alternate requirements project as a technical lead. Her depth of knowledge was cultivated at the University of Maryland, where Rachel graduated Summa Cum Laude with a degree in mechanical engineering.

Authors:

Rachel Romano MPR Associates, Inc.
Suzanne McKillop MPR Associates, Inc.
Bob Keating MPR Associates, Inc.