Document: NRC Regulatory Guide
Document ID: 626cd346-6298-4966-a92d-c5d4b24bbc2b
Document Type: regulatory_guide
Title: Overhead Crane Handling Systems for Nuclear Power Plants
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1303/ML13038A096.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.104
CFR Part: 
CFR Title: 

Content:
ear if it rubs excessively on the sides of the grooves in the drum and sheaves due to improper alignment or large fleet angles between the grooves. The load-carrying rope will furthermore suffer shock loading if it is partly held by friction on the groove wall and then suddenly released to enter the bottom of the groove. The rope can be protected by the selection of conservative fleet angles. Ropes may also suffer damage due to excessive strain developed if the cable construction and the pitch diameter of the sheaves are not properly selected. Fatigue stress in ropes can be minimized when the pitch diameter of the sheaves are selected large enough to produce only nominal stress levels. The pitch diameter of the sheaves should be larger for ropes moving at the highest velocity near the drum and can be smaller for sheaves used as equalizers where the rope is stationary. Equalizers for stretch and load on the rope reeving system may be of either beam or sheave type. A dual rope reeving system with individual attaching points and means bor balancing or distributing the load between the two operating rope reeving systems will permit either rope system to hold the critical load and maintain bal- ance in case of failure of the other rope system. Selection of hoisting speed is influenced by such items as reaction time for corrective action for the hoist- ing movement and the potential behavior of a failed rope. To prevent or limit damaging effects that may re- sult from dangerous rope spinoff in case of a rope break, the hoisting speed should be limited. A 5 fpm hoisting speed limit is an acceptable limit. The rope traveling speed at the drum is higher than at other points in the reeving system, and the potential for damage due to rope flailing and interference with other parts of the system should be considered. Conservative industry practice limits the rope line speed to 50 fpm at the drum as a conservative approach. Power transmission gear trains are often supported by