The role of codes and standards in the design process

Codes and standards are an important part of both the beginning and end of the design process for a nuclear plant. At the beginning of the process they represent the starting point for new designs or design improvements. At the end of the process, they formally document design experience and the corresponding implementation procedures. In the United States, the nuclear codes, industry standards, and regulatory review guidelines document a great deal of experience, which has resulted in more than 275 industry codes and standards and approximately 15,000 regulatory guidance documents. Consistency with this experience is a critical part of any nuclear design effort. Use of consistent codes, standards, and regulatory guidance for a family of plants helps ensure design standardization and, consequently, maintenance and operating efficiency. For example, requiring changes in the methods for seismic or environmental qualification of components would require the utility to maintain two different qualification programs for a standard design family. The role of codes, standards; and regulatory guidance has also been recently demonstrated in the design certification process for two evolutionary Advanced Light Water Reactors (ALWRs)-General Electric's ABWR design and ABB-CE's System 80+ design. Codes, standards, and regulatory guidance are not static since they must change to reflect new design objectives and regulatory guidance are not static since they must change to reflect new design objectives and regulatory issues. New design requirements come from both operating experience and from regulatory issues. New design requirements come from both operating experience and from regulatory issues. New design requirements come from both operating experience and from changes in public demand. In the United States, utilities demand nuclear plants that are not only safer than current designs, but also more efficient to maintain and operate. These requirements have been developed over the past ten years and incorporated into the ALWR Utility Requirements Document (URD) sponsored by utilities world-wide and coordinated by the Electric Power Research Institute (EPRI). Resolution of regulatory issues is a difficult step in the licensing process and usually results in requirements for new analysis methods or design features. Regulators can work closely with industry in the development of codes, standards, and criteria such as in the development of new methods for the design of piping and equipment supports. However, regulators can also demand that design criteria be established to address new issues or they can resist changes and analytical improvements proposed by the industry, as in the case for a subset of the Institute of Electrical and Electronics Engineers (IEEE) Standards. The final step in the use of codes, standards, and regulatory guidance is their formal documentation so that they can be used for design of similar plants in the future. Proposed codes and standards were used in the System 80+ design process. New regulatory and industry criteria developed during the review of the System 80+ were also evaluated and utilized in the design. Consequently, formal revisions to industry codes and standards remain to be incorporated in the System 80+ Design Control Document as they are finalized