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Exams > 2022 Q26 — EOP-FRHS-2 AFW Isolation

2022 Q26 — EOP-FRHS-2 AFW Isolation

⚠️ DRAFT
Q26 — EOP-FRHS-2 AFW Isolation W E13 EK3.2 (2.9)
Given:

• Unit 2 is implementing 2-EOP-FRHS-2, Response to Steam Generator Overpressure, due to high pressure in 21 Steam Generator.
• The crew is at Caution step C6-1 that reads "AFW FLOW SHOULD REMAIN ISOLATED TO AFFECTED SG(s) UNTIL A STEAM RELEASE PATH IS ESTABLISHED".

In accordance with 2-EOP-FRHS-2, which ONE of the following is the reason for this step?
A. Operation of the Turbine Driven AFW Pump at high steam pressure may cause turbine damage.
B. AFW is a high pressure system which may cause further overpressure in a SG with no steam release path.
C. Differential temperatures between the existing high pressure conditions in the SG and the cold AFW will cause tube failure due to thermal stress.
D. AFW pumps would operate near their shutoff head which could result in pump overheating or damage.
▶ Show Answer & Explanation
✓ B. Correct. IAW 2-EOP-FRHS-2, step C6-1 bases, if AFW flow is reestablished to an affected SG prior to establishing a steam release path, the AFW flow could further increase the affected SG pressure.
✗ A. Incorrect. Plausible the 23 AFW Pump is used as a means to vent the SG(s) and the candidate may believe that high pressure in the affected SG could cause damage to the turbine blades.
✗ C. Incorrect. Plausible since this bases is used on other FRHS procedures but it is not the reason for this action in FRHS-2.
✗ D. Incorrect. Plausible because the applicant may fail to recall that the AFW pumps have min flow protection.
Ref: 2-EOP-FRHS-2, Rev 40 | LO: NOS05FRHS00, Objective 10 | Source: Bank – DC Cook 2018 NRC RO25 | Cognitive: Fundamental/Memory

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