Document: NUREG-0800
Document ID: 4b58df3f-1f93-4271-aa73-22de04083915
Document Type: srp
Title: LOSS OF NORMAL FEEDWATER FLOW
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0703/ML070300709.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15.2.7
CFR Part: 
CFR Title: 

Content:
t be evaluated and verified. 3. The applicant's analysis of the loss of normal feedwater transient should be performed using an acceptable analytical model. If the applicant proposes to use analytical methods which have not been approved, these methods are evaluated by the staff for acceptability. For new generic methods the reviewer requests an evaluation by the appropriate organization for reactor systems. The value of parameters used in the analytical model should be suitably conservative. The following values are considered acceptable for use in the model. A. The initial power level is taken as the licensed core thermal power for the number of loops initially assumed to be operating plus an allowance of 2% to account for power measurement uncertainties, unless a lower power level can be justified by the applicant. The number of loops operating at the initiation of the event should correspond to the operating condition which maximizes the consequences of the event. 15.2.7-6 Revision 2 - March 2007 B. Conservative scram characteristics are assumed, i.e., for a PWR – maximum time delay with the most reactive rod held out of the core and for a BWR – a design conservatism factor of 0.8 times the calculated negative reactivity insertion rate, unless (a) a different conservatism factor can be justified through the uncertainty methodology and evaluation, or (b) the uncertainty has otherwise been accounted for (see SAR (or DCD) Section 4.4). C. The core burnup is selected to yield the most limiting combination of moderator temperature coefficient, void coefficient, Doppler coefficient, power profile and radial power distribution. D. Mitigating systems should be assumed to be actuated in the analyses at setpoints with allowance for instrument inaccuracy in accordance with Regulatory Guide 1.105. 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