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:
ts 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 fabricated weldments of structural parts. The proper alignment of shafts and gears depends on the adequacy of bearings and their supports to maintain correct align- ment of all components. The proper functioning .of the hoisting machinery during load handling can best be en- sured by providing adequate support strength and proper alignment of the individual component parts and the welds or bolting that binds them together. Bridge and Trolley. Failure of the bridge and trolley travel to stop when power is shut off could result in uncontrolled incidents. This would be prevented if both bridge and trolley drives are provided with control and holding braking systems which will be automatically applied when the power is shut off or if an overspeed or overload condition occurs because of malfunction or failure in the drive system. Sufficient braking capacity would be needed to overcome torque developed by the drive motor and the power necessary to decelerate the bridge or trolley with the attached load to a complete stop. A holding or control capacity of 100 percent of the maximum torque developed at the point of brake application would be an acceptable capacity for each braking system. Drag-type brakes are subject to excessive wear, and the need for frequent service and repair tends to make this type of brake less reliable; they therefore should not be used to control movements of the bridge and trolley. The travel speed of the trolley and bridge will in- fluence the operation of the crane as well as the equip- ment design and selection. Numerous crane applications have been studied and it has been concluded that the travel speed for nuclear power plant application should be conservatively selected. Trolley and bridge speed limits of 30 fpm and 40 fpm, respectively, have