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:
kes. The holding brakes should be activated when power is off and should be automatically mechani- cally tripped on overspeed to the full holding position if malfunction occurs in the electrical brake controls. Each holding brake should be designed to 125%-1150% of the maximum developed torque at point of application (lo- cation of the brake in the mechanical drive). The mini- mum design requirements for braking systems that will be operable for emergency lowering after a single brake failure should be two holding brakes for stopping and controlling drum rotation. Provisions should be made for manual operation of the holding brakes. Emergency brakes or holding brakes which are to be used for manual lowering should be capable of operation with full load and at full travel and provide adequate heat dissipation. Design for manual brake operation during emergency lowering should include features to limit the lowering speed to less than 3.5 fpmrL n. The dynamic and static alignment of all hoisting machinery components including gearing, shaft- ing, couplings, and bearings should be maintained throughout the range of loads to be lifted, with all com- ponents positioned and anchored on the trolley ma- chinery platform. o. Increment drives for hoisting may be pro- vided by stepless controls or inching motor drive. Plug- ging3 should not be permitted. Controls to prevent plug- ging should be included in the electrical circuits and the control system. Floating point 4 in the electrical power system when required for bridge or trolley movement should be provided only for the lowest operating speeds. p. To avoid the possibility of overtorque within the control system, the horsepower rating of the 3Plugging is the momentary application of full line power to the drive motor for the purpose of promoting a limited movement. 4That point in the lowest range of movement control at which power is on, brakes are off, and motors are not energized. motion of the overnead brsage crane