Document: NUREG-0800
Document ID: 0f072807-5b7f-4a13-85e3-594352505a7e
Document Type: srp
Title: TURBINE GENERATOR
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052350054.pdf
Revision Date: 2023-06
Chapter: 10
Section ID: 10.2
CFR Part: 
CFR Title: 

Content:
ontrol valves and reheat steam stop and intercept valves should be provided to protect the turbine from exceeding set speeds and to protect the reactor system from abnormal surges. The reheat stop and intercept valves should be capable of closure concurrent with the main steam stop valves, or of sequential closure within an appropriate time limit, to assure that turbine overspeed is controlled within acceptable limits. The valve arrangements and valve closure times should be such that a failure of any single valve to close will not result in excessive turbine overspeed in the event of a TGS trip signal. 3. The extraction steam check valves provided at extraction connections shall be capable of closing within an appropriate time limit to maintain stable turbine speeds in the event of a TGS trip signal. 4. The TGS should be provided with the capability to permit periodic testing of components important to safety while the unit is operating at rated load. 5. An inservice inspection program for main steam and reheat valves should be provided and it should include the following provisions: a. At approximately 3-1/3-year intervals, during refueling or maintenance shutdowns coinciding with the inservice inspection schedule required by Section XI of the ASME Code for reactor components, at least one main steam stop valve, one main steam control valve, one reheat stop valve, and one reheat intercept valve should be dismantled and visual and surface examinations conducted of valve seats, disks, and stems. If unacceptable flaws or excessive corrosion are found in a valve, all other valves of that type should be dismantled and inspected. Valve bushings should be inspected and cleaned, and bore diameters should be checked for proper clearance. b. Main steam stop and control valves and reheat stop and intercept valves should be exercised at least once a week by closing each valve and observing by the valve position indicator that it moves smoothly to a fully closed position. At