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:
The NRC safety objective for turbine missiles (i.e., P should be < 10 per year per plant) is best expressed in terms of either of 4 -7 two sets of criteria applied to missile generation probability, P . All applicants are 1 expected to commit to operating criteria (see Table 3.5.1.3-1) appropriate to the applicable turbine orientation. One set of criteria should be applied to favorably oriented turbines; the other should be applied to unfavorably oriented turbines. This approach places responsibility on the applicant for initially demonstrating, and thereafter maintaining, an NRC-specified turbine reliability. Accordingly, the applicant should commit to conduct appropriate inservice inspection and testing throughout the life of the plant. This requires the applicant to demonstrate the capability to perform volumetric (ultrasonic) examinations suitable for inservice inspection of turbine disks and shafts and to provide reports describing the applicant's methods for determining turbine missile generation probabilities (Refs. 5, 13, and 14) for NRC review and approval.24 TABLE 3.5.1.3-1 PROBABILITY OF TURBINE FAILURE RESULTING IN THE EJECTION OF TURBINE DISK (OR INTERNAL STRUCTURE) FRAGMENTS THROUGH THE TURBINE CASING (P ) 1 AND REQUIRED LICENSEE ACTIONS25 CA PROBABILITY PROBABILITY SE PER YEAR FOR PER YEAR FOR REQUIRED LICENSEE ACTION A FAVORABLY AN ORIENTED UNFAVORABL TURBINE Y ORIENTED TURBINE 3.5.1.3-7 DRAFT Rev. 3 - April 1996 A P < 10 P < 10 This condition represents the general, 1 -4 1 -5 minimum reliability requirement for loading the turbine and bringing the system on line. B 10 < P < 10 10 < P < 10 If this condition is reached during -4 -3 1 -5 -4 1 operation, the turbine may be kept in service until the next scheduled outage, at which time the licensee must take action to reduce P to meet the 1 appropriate Case A criterion before returning the turbine to service. Exemptions may be granted for valid technical reasons or to mitigate severe economic hardship. C