Q34 — PRT Rupture Disc / High Pressure Response
007 A2.03 (3.6)
Given:
• Unit 2 is responding to a Loss of Heat Sink.
• During cycling of the PZR PORVs due to high PZR pressure, 2PR1 failed open.
• The crew closed 2PR6, PZR PORV Block Valve, to isolate the failed open 2PR1.
Subsequently, Console Bezel Alarm, PRT PRESS HI, is now LIT
• PRT Pressure is indicating 12 psig.
Which ONE of the following completes both statements?
1. What would be the impact to the PRT if the PZR PORV could not be isolated?
2. In accordance with the Alarm Response Procedure for "PRT PRESS HI", what action can be performed to reduce PRT pressure?
• Unit 2 is responding to a Loss of Heat Sink.
• During cycling of the PZR PORVs due to high PZR pressure, 2PR1 failed open.
• The crew closed 2PR6, PZR PORV Block Valve, to isolate the failed open 2PR1.
Subsequently, Console Bezel Alarm, PRT PRESS HI, is now LIT
• PRT Pressure is indicating 12 psig.
Which ONE of the following completes both statements?
1. What would be the impact to the PRT if the PZR PORV could not be isolated?
2. In accordance with the Alarm Response Procedure for "PRT PRESS HI", what action can be performed to reduce PRT pressure?
A. 1) A rupture disc will rupture at 100 psig.
2) Drain the PRT to lower level and pressure.
2) Drain the PRT to lower level and pressure.
B. 1) A relief valve will open at 100 psig.
2) Drain the PRT to lower level and pressure.
2) Drain the PRT to lower level and pressure.
C. 1) A rupture disc will rupture at 100 psig.
2) Open the 2PR15 to vent the PRT.
2) Open the 2PR15 to vent the PRT.
D. 1) A relief valve will open at 100 psig.
2) Open the 2PR15 to vent the PRT.
2) Open the 2PR15 to vent the PRT.
▶ Show Answer & Explanation
✓ A. Correct. A stuck open PZR PORV will cause the PRT pressure, level, and temperature to rise. PRT pressure at 10 psig will close the 2PR15 and cannot be opened until PRT pressure is less than 10 psig. IAW S2.OP-SO.PZR-0003 step 4.2.2, if 2PR15 cannot open due to PRT pressure of 10 psig, then the PRT level adjustment is necessary to lower PRT pressure and clear the interlock to allow 2PR15 to open. IAW step 4.1.2 for PRT level high, the 2PR14 drain valve is opened first to lower level then the 2PR15 is opened to vent PRT down to 3 psig. The ARP for PRT PRESS HI also states to drain the PRT to lower level and pressure. The PRT rupture discs rupture at 100 psig.
✗ B. Incorrect. First part is incorrect. The PRT does not have a relief valve and instead uses a rupture disc that opens at 100 psig. Second part is correct. Plausible if the operator believes that the PRT has a relief valve.
✗ C. Incorrect. First part is correct. Second part is incorrect. 2PR15 vent valve will not open when PRT pressure is ≥ 10 psig.
✗ D. Incorrect. First part is incorrect. The PRT does not have a relief valve and instead uses a rupture disc that opens at 100 psig. Second part is incorrect. 2PR15 vent valve will not open when PRT pressure is ≥ 10 psig. Plausible if the operator believes that the PRT has a relief valve and that the 2PR15 vent valve is still available when PRT pressure is above 10 psig.
Ref: NOS05PZRPRT-08, S2.OP-SO.PZR-0003, S2.OP-AR.ZZ-0012 | LO: NOS05PZRPRT-08, Objective 15 — Given a Pressurizer and Pressurizer Relief Tank failure, predict the effect of the Pressurizer and Pressurizer Relief Tank failure on the following: Containment | Source: New | Cognitive: Comprehension/Analysis
Connections
- Related systems: Pressurizer & PRT
- Related procedures: S2.OP-SO.PZR-0003 — PRT Operations, S2.OP-AR.ZZ-0012 — Console Alarm Response
- Related exam: 2022 NRC Written Exam