2018 Q55 — PZR Pressure Channel Fails High / PORV Logic

✓ B. Correct. 2PR1 and 2PR2 require 2 channels (PT-455/PT-457 or PT-456/PT-474) to read greater than 2335 psig for the PORV to open. Consequently, at 22:00:05 with ONLY PT-455 reading greater than 2335 psig (due to PT-455 failing high), NO Power Relief Valves (2PR1 and 2PR2) are open.

✗ A. Incorrect but plausible. The candidate could incorrectly conclude the PORVs open based on the master pressure controller. Consequently, when the controlling pressure channel fails (PT-455), the candidate would then incorrectly conclude that BOTH PORVs are open at 22:00:05.

✗ C. Incorrect but plausible. The candidate could correctly realize that operation of the PORVs is dependent on specific PZR Pressure Transmitters. However, the candidate could then incorrectly understand how the PORV open logic works and/or which pressure transmitters operate each specific PORV. This would cause the candidate to incorrectly conclude that ONLY 2PR1 or ONLY 2PR2 is open at 22:00:05.

✗ D. Incorrect but plausible. The candidate could correctly realize that operation of the PORVs is dependent on specific PZR Pressure Transmitters. However, the candidate could then incorrectly understand how the PORV open logic works and/or which pressure transmitters operate each specific PORV. This would cause the candidate to incorrectly conclude that ONLY 2PR1 or ONLY 2PR2 is open at 22:00:05.

Ref: NOS05PZRP&L-10 (Pressurizer Pressure and Level Control), Drawing 231357 (Units 1 & 2 Pressurizer 1PR1, 2PR1, 1PR2, 2PR2 Press. Power) | LO: NOS05PZRP&L-10 | Source: New | Cognitive: Higher