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:
with their wheels prevented from leaving the tracks during, a seismic event. If a seismic event comparable to a safe shutdown earthquake (SSE) occurs, the bridge should remain immobile on the runway, and the trolley with load should remain im- mobile on the crane girders. Since all the crane loading cycles will produce cyclic stress, it may be necessary to investigate the potential for failure of the metal due to fatigue. When a crane will be used for the construction period, it will experience additional cyclic loading, and these loads should be added to the expected cyclic loading for the permanent plant operation for the fatigue evaluation. Materials and Fabrication Bridge and trolley structures are generally fabricated by welding structural shapes together. Problems have been experienced with weld joints between rolled struc- tural members. Specifically, subsurface lamellar tearing has occurred at the weld joints during fabrication and the load-bearing capacity of the joint has thus been re- duced. Radiography or ultrasonic inspection, as appro- priate, of all load-bearing weld joints would help to ensure the absence of lamellar tearing in the base metal and the soundness of the weld metal; Other problems with welding of low-alloy steels can occur if the base metal temperature is not properly controlled during welding and the postweld heat treatment. Regulatory Guide 1.50, "Control of Preheat Temperature for Weld- ing of Low-Alloy Steel," identifies this potential prob- lem and indicates an acceptable procedure for obtaining sound welds in low-alloy steels. Cranes are generally fabricated from structural shapes and plate rolled from mild steel or low-alloy steel. Some of these steel parts exceed ½ inch in thickness and may have brittle-fracture tendencies during some of the intended operating temperatures, so that testing of the material toughness becomes necessary. Specifically, the nil-ductility transition temperature (NDTT) should be determined. Safety