ESD Flashcards
Describe the difference in indications for large Steam Line Break in Containment and Large Feed Water rupture in Containment.
Steam Break: Tc goes down, Reactor Power goes up before trip. SGWL goes up initially and then goes down. Steam pressure drops rapidly, Containment Pressure goes up. Sub cooling goes up.
Feed water break: SGWL goes down rapidly, SG pressure remains constant until SGWL is almost empty. Rx Power initially rise. Tc goes up initially until SG empties and then goes down (nowhere near as much as steam break)
Why are 2 RCPs secured when RCS remains below the SIAS set point in ESD
Trip 2 Leave 2 is a generic strategy for RCS depressurization events.
It maintains forced circulation for Non-LOCA depressurization events, and for LOCA events in which the rate of inventory loss is not unduly exacerbated by leaving 2 RCPs in service.
What is more of a concern with regard to Pressurized thermal shock, Forced Circulation or Natural Circulation?
What extra direction is giving when stabilizing the RCS.
Natural Circulation is more of a concern.
If P/T limits were exceeded and no RCPs are running, maintain current temperature and pressure for 2 hours.
Why should SG Pressures be maintained less than RCS pressure, and one RCP be in operation when drawing a bubble in the pressurizer?
Minimizes the possibility of a void formation in the SG U-Tubes.
Maintaining pressure in both steam generators less than RCS pressure ensures that the SG steam space and consequently the top portion of the U-tubes will be the coolest part of the RCS, thus preventing void formation.
A bubble will form with or without RCPs operating. It will form quicker with a RCP running due to the increased heat removal.
How should PZR level be controlled if Let Down is unable to be restored and NCW is unavailable.
Why?
If PZR level is 65% or more, and let down is not able to be restored with NCW unavailable to RCP seals, commence an RCS cool down.
Securing the last CH pump would terminate Seal Injection flow to RCPs.
If there is no cooling to the RCP seals, RCP seal integrity becomes jeopardized.
PZR level is 70% and rising. No NCW flow exists. The crew wishes to commence a plant cool down. Shutdown margin has not been verified. Can the cool down commence?
Why?
Yes.
Per the tech guide, Maintaining RCP seal integrity to prevent complicating the emergency has priority over establishing shutdown margin.
