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Part 1: Technical Position on Piping System Installation Tolerances

The Technical Position provides tolerances on the as-built geometry of Light Water Reactor piping and pipe support locations that are considered acceptable for reconciliation with as-designed geometry. That is, a piping system geometry that is in compliance with the plant licensing commitments based on the as-designed documentation is also considered to be in compliance if the reported as-built critical to design dimensions do not exceed the total tolerances presented in the Technical Position.

Currently, most nuclear power plant construction activities involve a significant amount of time and dollars related to reconciling the as-built piping and support locations with the as-designed configuration. This occurs because it is impractical, if not impossible, to fabricate and install piping and pipe supports to the exact dimensions given on the design drawings. However, the design documentation, including analyses, must rely on the as-designed geometry since it is necessary to determine initial design acceptability prior to release for construction. In the end any significant differences must be reconciled.

Part 2: Technical Position on Damping Values for Insulated Pipe - Summary Report

Under the direction of the Steering Committee on Piping Systems of the Pressure Vessel Research Committee, the Task Group on Damping Values of the Technical Committee on Piping Systems prepared a position document on pipe damping. This document recommended that higher damping values be used for seismic design of pipe systems than those set forth in Regulatory Guide 1.61.

These recommendations were based on analysis of twenty-one data groups obtained from both laboratory in in situ pipe damping tests as presented in the detailed draft report. Sixteen of these data groups were obtained from uninsulated Light Water Reactor (LWR) pipe systems. Single data sets from lightly insulated LWR pipe were contained in two data groups and several data sets from heavily insulated Liquid Metal Reactor (LMR) pipe were contained within three data groups.

Light insulation was found to have no apparent effect on damping. Conversely, the heavily insulated LMR pipe was noted to have significantly higher damping. The Task Group recognized that heavy insulation could increase damping but that the amount of data available was insufficient to quantify this effect. The Task Group then judged the heavily insulated data as non-typical and did not use it in formulating their 1983 technical position. The technical position was therefore based on uninsulated and lightly insulated pipe damping data.

Product Details

Published: 1986 Number of Pages: 24 File Size: 1 file , 810 KB