Document: NUREG-0800
Document ID: 504a24fe-9056-495a-8541-0e278016ce80
Document Type: srp
Title: in that offsite AC power remains available to operate the station
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0703/ML070300702.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15.2.6
CFR Part: 
CFR Title: 

Content:
pical BWR and PWR plants, position switches on the TSVs sense the trip and initiate reactor scram. The remainder of this transient is similar to the loss of external load. 3. Loss of Condenser Vacuum: A loss of condenser vacuum event is a malfunction that can result in a turbine trip; thus, the remarks in paragraph 2 apply to this event. In addition, due to system interaction, the loss of condenser vacuum event also causes the feedwater pumps to trip due to low suction pressure. The corresponding peak pressure in the primary and secondary systems requires separate analysis because the initial conditions that lead to peak pressure are different for the primary and secondary systems. 4. Main Steam Isolation Valve (MSIV) Closure: MSIV closure for BWRs can be initiated by various steam line or reactor system malfunctions and operator actions. As the MSIVs close, position switches initiate a reactor scram when valves in three or more steam lines are less than 90 percent open, the reactor pressure is above 4140 kPa (600 psi), and the reactor mode switch is in the “RUN” position. The effect of MSIV closure is limited steam flow to the turbine. The results are similar to those addressed in paragraph 1 but less severe because the MSIV closure time is longer than that of the TCVs. 5. Steam Pressure Regulator Failure: Steam pressure regulator failure in a closed position yields a transient similar to those previously addressed. Generally, the rate of change of system parameters is slower for a steam pressure regulator failure and a less severe transient results. 15.2.1-15.2.5-3 Revision 2 - March 2007 6. Review of these five described transients includes the sequence of events, the analytical models, the values of parameters in the analytical models, and the predicted consequences of the transients. A. The sequence of events described in the SAR (or DCD) analysis is reviewed by the organization responsible for reactor systems in consultation with the organization