Document: NUREG-0800
Document ID: 90914152-fc84-4413-a5f5-aa75efd21205
Document Type: srp
Title: TURBINE MISSILES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0636/ML063600395.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.5.1.3
CFR Part: 
CFR Title: 

Content:
10-3 per year per plant. B. For unfavorably oriented turbine generators, the product of P2 and P3 tends to be in the range of 10-3 to 10-2 per year per plant. Favorably oriented turbine generators are located such that the containment and all, or almost all, safety-related SSCs outside containment are excluded from the low-trajectory hazard zone described in RG 1.115. Because of assumptions and modeling difficulties in the probabilistic calculations as described above, the staff does not encourage applicants to calculate P2, P3, or their product. Instead, the staff accepts a product of strike and damage probabilities of 10-3 per year per plant for a favorably oriented turbine and 10-2 per year per plant for an unfavorably oriented turbine. The suggested values represent the staff's best estimate of the product of P2 and P3, based on the results of calculations performed at the NRC (NUREG-1048, Supplement No. 6, and NUREG-0887, Supplement No. 3) and elsewhere. 2. Operating experience indicates that turbine rotor crack (NUREG/CR-1884; PNO-111-81- 104; and NRC Memorandum from E. Jordan to W. Russell), turbine stop and control valve failures (J.J. Burns, Jr.; License Event Report No. 82-132, Docket No. 50-361; and NRC Memorandum from E. Jordan to W. Russell), blade failures, and rotor ruptures can result in the generation of high-energy missiles (D. Kalderon and NRC Memorandum from E. Jordan to W Russell). Analyses indicate that missile generation can be modeled and the probability of missile generation can be strongly influenced by a suitable program of periodic inservice testing and inspection. 3.5.1.3-5 Revision 3 - March 2007 In general, two modes of turbine rotor failure can result in turbine missile generation: (a) rotor material failure at approximately the rated operating speed and (b) failure of the overspeed protection system. Failure of turbine rotors at or below the design speed (nominally, 120% of normal operating speed) can be caused by small flaws or