Document: NUREG-0800
Document ID: dfb421c6-cf9c-447e-ab71-dd0426ce50e5
Document Type: srp
Title: TURBINE MISSILES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340523.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.5.1.3
CFR Part: 
CFR Title: 

Content:
ragment trajectories 3,max ejected from the j- wheel. = 10? for inner wheels = 25? for end wheels. = Elevation angle subtended by the target. a = Maximum elevation angle range for a missile (e.g., max for a single fragment the probability of any given elevation angle is uniformly distributed over 2n radians, Omax = 360?). An additional factor-f may be used to multiply the above relation if Penetration of intermediate barriers is conditional on missile state. This can be done by considering the ratio of all missile states that penetrate the barrier to the total number of missile states. If there are M barriers, this may be expressed as . th f = n (All missile states that penetrate 6.-barrier)ij m- l (Total number of possible missile statesjij 3.5.1;3-5 Rev 2 - July 1981 where the i and j indices refer to the turbine failure mode and failed wheel, respectively. Estimates of the potential for concrete penetration and/or scabbing are .based on the missile penetration criteria described in SRP Section 3.5.3. The evaluation of the overall probability P is performed by considering conservative as well as realistic estimates of all the individual parameters that are used 'in the analysis. The conservative and realistic estimates of P are used in conjunction with the risk acceptance guidelines described in SRP Section 2.2.3 in determining the acceptability of the plant design with respect to turbine missile risk. 3. The reviewer may request technical assistance on an as needed basis in the following areas in order to complete the turbine missile evaluation: a. Where the design basis protection against turbine missiles is primarily by use of barriers, the adequacy of structural turbine barrier procedures are verified by the SEB in accordance with the criteria of SRP Section 3.5.3. b. The effect of fracture toughness properties on the failure probability of the low pressure turbine wheels is reviewed by the MTEB. c. The turbine overspeed protection system and its testing are