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Exams > 2019 Q52 — LOCA-3 SEC Reset and Blackout Loading

2019 Q52 — LOCA-3 SEC Reset and Blackout Loading

⚠️ DRAFT
Q52 — LOCA-3 SEC Reset and Blackout Loading EPE: 011 Large Break LOCA-EK2.02 (2.6)
Given:
• A LBLOCA is in progress at Unit 2

At time 10:00
• The crew has just reset SI and ALL SECs in accordance with 2-EOP-LOCA-3 (Transfer To Cold Leg Recirculation)

At time 10:05
• 2A 4KV Vital Bus de-energizes due to a SPURIOUS isolation from off-site power

In accordance with 2-EOP-LOCA-3, which ONE of the following completes the statements below?

At 10:00 and after resetting ALL of the SECs, the crew _(1)_ REQUIRED to ensure that the 230V control centers are reset.
After the 2A EDG loading is completed, the ECCS pumps on 2A 4KV Vital Bus _(2)_.

(1)(2)
A. (1) is (2) will start AUTOMATICALLY
B. (1) is (2) must be MANUALLY started
C. (1) is NOT (2) must be MANUALLY started
D. (1) is NOT (2) will start AUTOMATICALLY
▶ Show Answer & Explanation
✓ B. Correct. For Part 1, at 10:00 and after resetting ALL of the SECs, the crew is required to MANUALLY reset the 230V control centers (even though at 20 minutes after SEC actuation, this lockout is automatically removed). For Part 2, if a blackout loading sequence occurs on any 4KV vital bus with SI previously reset, then ECCS pumps and other safeguards equipment will not automatically start and must be manually operated if required since different equipment is started on a SEC blackout loading than on a safeguards loading.
✗ A. Incorrect but plausible. Part 1 is correct. For Part 2, the candidate could incorrectly conclude that after the blackout loading is completed, the ECCS pumps and safeguards equipment on 2A 4KV Vital Bus will start AUTOMATICALLY (since a LBLOCA is in progress).
✗ C. Incorrect but plausible. For Part 1, the candidate may fail to recognize that after resetting ALL of the SECs, the crew is required to MANUALLY reset the 230V control centers. Part 2 is correct.
✗ D. Incorrect but plausible. For Part 1, the candidate may fail to recognize that after resetting ALL of the SECs, the crew is required to MANUALLY reset the 230V control centers. For Part 2, the candidate could incorrectly conclude that after the blackout loading is completed, the ECCS pumps and safeguards equipment on 2A 4KV Vital Bus will start AUTOMATICALLY (since a LBLOCA is in progress).
Ref: 2-EOP-LOCA-3 (Transfer To Cold Leg Recirculation) | LO: NOS05LCA3U2-04 (TRANSFER TO COLD LEG RECIRCULATION) | Source: Bank — ILOT 1601 AUDIT RO 051 | Cognitive: Higher

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