Document: NUREG-0800
Document ID: 29fa664a-a42c-4ff0-8ae1-3798f7f23c23
Document Type: srp
Title: TURBINE MISSILES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070373.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.5.1.3
CFR Part: 
CFR Title: 

Content:
ing refueling or maintenance shutdowns (in accordance with the manufacturer's procedures) of all normally inaccessible parts such as couplings, coupling bolts, LP turbine shafts, blades and disks, and high-pressure (HP) rotors. Shafts and disks with crack depths at or near one-half the critical crack depth should be repaired or replaced. All cracked couplings and coupling bolts should be replaced. c. The inservice inspection and test program should be used for the governor and overspeed protection system to provide further assurance that flaws or component failures will be detected in the overspeed sensing and tripping subsystems, main steam control and stop valves, reheat steam intercept and stop valves, or ex- traction steam non-return valves — any of which could lead to an overspeed 3.5.1.3-9 DRAFT Rev. 3 - April 1996 condition above that specified by the design overspeed. The inservice inspection program for operability of the governor and overspeed protection system should include, at a minimum, the following provisions: (a) For typical turbine governor and overspeed protection systems, at intervals of approximately 3 years during refueling or maintenance shut- downs, at least one main steam control valve, one main steam stop valve, one reheat intercept valve, one reheat stop valve, and one of each type of steam extraction valve should be dismantled. Visual and surface examinations of valve seats, disks, and stems should be conducted. Valve bushings should be inspected and cleaned, and bore diameters should be checked for proper clearance. If any valve is shown to have hazardous flaws or excessive corrosion or improper clearances, the valve should be repaired or replaced; all other valves of that type should also be dismantled and inspected. (b) At least once a week during normal operation, main steam control and stop valves, reheat intercept and stop valves, and steam extraction non- return valves should be exercised by closing each valve and observing