Document: NUREG-0800
Document ID: cefc1d6c-e171-41f0-bdf3-b5d7ef6a7f43
Document Type: srp
Title: MISSILES GENERATED BY TORNADOES AND EXTREME WINDS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0703/ML070380174.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.5.1.4
CFR Part: 
CFR Title: 

Content:
. Regulatory Guide (RG) 1.76 describes acceptable design-basis tornado-generated missile spectrum for the design of nuclear power plants. 2. The method of identifying appropriate design-basis missiles generated by natural phenomena shall be consistent with the acceptance criteria defined for the evaluation of potential accidents from external sources in SRP Section 2.2.3. Other methodologies used by licensees and applicants with appropriate rationale may be acceptable on a case-by-case basis. Technical Rationale The technical rationale for application of these acceptance criteria to the areas of review addressed by this SRP section is discussed in the following paragraphs: 1. GDC 2 establishes requirements regarding the ability of SSCs important to safety to withstand a tornado without the loss of capability to perform their safety functions. Application of GDC 2 ensures that the chosen design basis reflects the most severe tornadoes historically reported for the site and surrounding region. A nuclear power plant must remain in a safe condition in the event of the most severe tornadoes that can reasonably be predicted. Designing a nuclear power plant to withstand the design-basis 3.5.1.4-4 Revision 3 - March 2007 maximum tornado wind speed and tornado missiles discussed in RG 1.76 ensures that SSCs important to safety will be capable of performing their safety function, and there will be no undue risk to the health and safety of the public in the event of the most severe tornado conditions. Evolutionary reactors should be designed based on regional wind speeds corresponding to strike probability of 10-7 per year, as defined in RG 1.76. 2. GDC 4 establishes requirements regarding the ability of SSCs important to safety to be protected from dynamic effects, including the effects of missiles, from events and conditions outside the nuclear unit. Tornadoes are dynamic events originating outside the nuclear unit; therefore, this criterion is applicable to the assessment