Q84 — EOP-TRIP-6 Nat Circ Cooldown Without RVLIS
W E10 EA2.2 (3.9)
Given:
• Unit 2 reactor tripped due to loss of all offsite power.
• The crew has verified natural circulation flow and is cooling down the plant per 2-EOP-TRIP-4, Natural Circulation Cooldown.
• Train A RVLIS is out of service for Maintenance.
• The Shift Manager directs the crew to perform a rapid cooldown and depressurization due to secondary inventory concerns.
Current plant conditions are:
• RCS Pressure is 1840 psig and stable.
• RCS Hot Leg temperatures are 540 °F and lowering.
• 2PT-405 Wide Range RCS Pressure has failed.
Based on the above conditions, what procedure will the CRS implement and what is the MAXIMUM allowable RCS cooldown rate in the procedure entered?
• Unit 2 reactor tripped due to loss of all offsite power.
• The crew has verified natural circulation flow and is cooling down the plant per 2-EOP-TRIP-4, Natural Circulation Cooldown.
• Train A RVLIS is out of service for Maintenance.
• The Shift Manager directs the crew to perform a rapid cooldown and depressurization due to secondary inventory concerns.
Current plant conditions are:
• RCS Pressure is 1840 psig and stable.
• RCS Hot Leg temperatures are 540 °F and lowering.
• 2PT-405 Wide Range RCS Pressure has failed.
Based on the above conditions, what procedure will the CRS implement and what is the MAXIMUM allowable RCS cooldown rate in the procedure entered?
A. 2-EOP-TRIP-5, Natural Circulation Cooldown with Steam Voids in Vessel (with RVLIS); 100 °F/hr.
B. 2-EOP-TRIP-5, Natural Circulation Cooldown with Steam Voids in Vessel (with RVLIS); 50 °F/hr.
C. 2-EOP-TRIP-6, Natural Circulation Cooldown with Steam Voids in Vessel (without RVLIS); 50 °F/hr.
D. 2-EOP-TRIP-6, Natural Circulation Cooldown with Steam Voids in Vessel (without RVLIS); 100 °F/hr.
▶ Show Answer & Explanation
✓ C. Correct. Based on plant conditions, Train B RVLIS is not available because 2PT-405 wide range pressure has failed and is an input into the RVLIS Train B. Both Trains of RVLIS are not available and the CRS should enter 2-EOP-TRIP-6. With RCS T-Hots > 500 °F, then the maximum allowable RCS cooldown rate is 50 °F/hr until RCS T-Hots are less than 450 °F, then the RCS cooldown rate is a maximum of 100 °F/hr.
✗ A. Incorrect. Based on the stem conditions, both trains of RVLIS are not available. Therefore, EOP-TRIP-5 is not the correct procedure to implement without RVLIS. Plausible because the SRO may believe that Train B RVLIS is still available because the SRO may confuse which Train of RVLIS the 2PT-405 inputs into and believe that it feeds Train A. The RCS cooldown rate is incorrect.
✗ B. Incorrect. Based on the stem conditions, both trains of RVLIS are not available. Therefore, EOP-TRIP-5 is not the correct procedure to implement without RVLIS. Plausible because the SRO may believe that Train B RVLIS is still available because the SRO may confuse which Train of RVLIS the 2PT-405 inputs into and believes that it feeds Train A. The RCS cooldown rate is correct.
✗ D. Incorrect. Cooldown rate of 100 °F/hr is allowed when RCS T-Hots are less than 450 °F. Plausible because both Trains of RVLIS are unavailable and could believe that the cooldown rate of 100 °F/hr is allowed based on the T-Hot temperatures.
Ref: 2-EOP-TRIP-5 (R40), EOP-TRIP-6 (R40) | LO: NOS05LOCA05-05, Objective 7 | Source: Bank – Beaver Valley U2 2015 NRC SRO85 | Cognitive: Comprehension/Analysis
Connections
- Related systems: RVLIS, RCS
- Related EOPs: EOP-TRIP-4 — Natural Circulation, EOP-TRIP-5 — Natural Circulation Cooldown With RVLIS, EOP-TRIP-6 — Natural Circulation Cooldown Without RVLIS
- Related exam: 2022 NRC Written Exam