Part 1: Technical Position on Criteria Establishment

Under the direction of the Steering Committee on Piping Systems of the Pressure Vessel Research Committee the Technical Committee on Piping Systems is developing positions in a number of areas which will have an effect on the design of piping systems. In the areas of criteria and loading this effort is currently concentrated on seismic issues but will also include other dynamic loads. In addition, the practices applied by industry in developing piping design are addressed. The major goal of the Technical Committee is to make recommendations for modification to Codes, standards, regulations and practices, so that a better balance exists between protection of piping against dynamic loading on the one hand while providing flexibility for expansion considerations on the other. It has been the opinion of a number of organizations and individuals in the industry that current criteria and practice are weighted on the side of protection against dynamic loading resulting in piping systems that are inflexible, over-supported and not as reliable as they could be.

Part 2: Technical Position on Damping Values for Piping-Interim Summary Report

This position document was prepared by the Task Group on Damping Values of the Technical Committee on Piping Systems under the guidance of the Steering Committee on Piping Systems of the Pressure Vessel Research Committee. The Task Group Members were: chairman, J. L. Bitner of Westinghouse Electric Corp., W. F. Anderson of the U.S. Nuclear Regulatory Commission, S. N. Hou of the U.S. Nuclear Regulatory Commission, and W. J. Kagay of the Tennessee Valley Authority.

This interim summary report is derived from the detailed draft report which is available for review only at PVRC headquarters. The detailed report provides comprehensive documentation of
(1) The data description, collection, and summarization process;
(2) The data evaluation methods and comparisons;
(3) Independent assessments of the technical position on damping values;
(4) Technical discussion and recommendations; and
(5) The original data sets and sources.

The interim summary report contains an abstract of the detailed report with focus on the Technical Position and recommendations for application.

Part 3: Technical Position on Response Spectra Broadening

The purpose of the Task Group on Spectra Development was to determine and recommend, to the Technical Committee on Piping Systems, more reasonable methods that can be used in performing seismic analysis of nuclear power piping systems, and provide technical defense as required. This report summarizes a proposed change to the current response spectra peak broadening requirements.

Part 4: Technical Position on Industry Practice

The PVRC Technical Committee on Piping Systems, in addressing the piping design process, recognized that certain "practices" in the industry were so heavily oriented to designing for the various postulated extreme loading events that little, if any, emphasis was being given to optimum design for the actual loadings normally expected to occur in power piping systems. The committee perceived these practices to be contributing significantly to potential unreliability as were certain requirements in Codes and Regulations. The committee could not attack all such areas, therefore a certain few that were felt to be the most critical were selected. These areas were:
(1) The restraint selection process-snubbers vs. other linear devices.
(2) The design process for small bore piping.
(3) Equipment loads in the design process.
(4) The integration of the design process.

The discussions contained in this paper are intended to stimulate organizations to recognize these problem areas and to address them in a manner similar to the approaches presented here. The techniques and guidelines in the following sections are not intended to be hard and fast rules. In many cases, organizations responsible for areas discussed in this paper have procedures in place that resolve the problems.

It is hoped that the items addressed in this paper will stimulate discussion in the industry and that interested organizations will submit comments and suggestions for study by the Technical Committee.