Q2 — PORV Discharge Temperature
000008AK2.02 (2.7)
Given:
• Unit 2 is in MODE 3.
• RCS Pressure is 2235 psig
• PZR Power Operated Relief Valve (PORV) 2PR1 is leaking.
• Pressurizer Relief Tank (PRT) pressure is 5 psig.
• PORV discharge temperature has stabilized at 230 °F.
Which ONE of the following will directly cause the indicated PORV discharge temperature to LOWER?
• Unit 2 is in MODE 3.
• RCS Pressure is 2235 psig
• PZR Power Operated Relief Valve (PORV) 2PR1 is leaking.
• Pressurizer Relief Tank (PRT) pressure is 5 psig.
• PORV discharge temperature has stabilized at 230 °F.
Which ONE of the following will directly cause the indicated PORV discharge temperature to LOWER?
A. PRT rupture disk develops a leak.
B. PRT pressure is allowed to rise to 10 psig.
C. RCS pressure is reduced to 2000 psig.
D. PORV leakrate rises by 5 gpm.
▶ Show Answer & Explanation
✓ A. Correct. Leaking rupture disk lowers PRT pressure, constant enthalpy process to lower PRT pressure results in lower discharge temperature. (see constant enthalpy process on Mollier Diagram)
✗ B. Incorrect. Plausible because candidate may believe that rising PRT pressure causes discharge temperature to lower. Incorrect because higher PRT pressure results in higher discharge temperature. (see constant enthalpy process on Mollier Diagram)
✗ C. Incorrect. Plausible because candidate may believe that the lowering of RCS pressure will reduce the discharge temperature. (see constant enthalpy process on Mollier Diagram)
✗ D. Incorrect. Plausible because candidate may believe that an increasing leak rate will lower discharge temperature. (see constant enthalpy process on Mollier Diagram)
Ref: NOS05PZRPRT-06 | LO: Objective 15 | Source: Modified – Salem 2004 NRC Exam | Cognitive: Comprehension
Connections
- Related systems: Pressurizer & PRT
- Related exam: 2020 NRC Written Exam