Document: NUREG-0800
Document ID: 1d0646de-ae93-4092-a3da-716f2bb7afba
Document Type: srp
Title: TECHNICAL SPECIFICATIONS AND EMERGENCY OPERATION REQUIREMENTS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340561.pdf
Revision Date: 2023-06
Chapter: 2
Section ID: 2.4.14
CFR Part: 
CFR Title: 

Content:
ovided an emergency flood protection plan designed to minimize the impact of floods exceeding plant grade on safety-related facilities, and a corresponding proposed technical-specification out- lining the action to be taken to prevent any flood-caused accidents. 2.4.14-2 Rev. 2 - July 1981 The applicant's flood protection plan is designed to meet the criteria of Regulatory Guide 1.59, position 2 and Regulatory Guide 1.102, position 2. It includes procedures for predicting rainfall floods, arrangements to warn of upstream seismically induced dam failure floods, and lead times available and types of action to be taken to meet safety-related requirements for both sources of flooding. The applicant's warning scheme for both types of floods is to be divided into two stages. Stage I will allow preparation steps and some damage, but will with- hol.d major economic damage until Stage II warning assures a flood above plant grade. Reservoir levels for large rainfall floods can be predicted well in advance by the applicant. The applicant estimates that a minimum of 27 hours, divided into the two warning stages, will be available between the time a preflood preparation order is issued and the time the flood water could exceed plant grade. A minimum 10-hour Stage I will begin upon prediction that flood producing conditions might develop. A minimum 17-hour Stage II will be based on a confirmed estimate that conditions will produce a flood above plant grade. Seismically-induced failure of upstream dams can result in flood surges that exceed plant grade. However, such surges do not have a water level potential as great as the rainfall-induced probable maxi- mum flood water level. A minimum of 27 hours, divided into the warn- ing stages, is estimated by the applicant to be available to prepare the plant for such flooding. The applicant defines "flood mode" operation as the means by which the plant will be safely maintained during the time when flood waters exceed plant grade,