JPM RO-A1 — Determine Maximum Vent Time in EOP-FRCI-3
Admin | RO/SRO | G2.1.25 (3.9)
Location: Classroom
Time-Critical: No
Alternate Path: No
Estimated Time: 8 minutes
Initial Conditions:
- Unit 2 has experienced a small break LOCA.
- The crew has performed an RCS cooldown and depressurization in EOP-LOCA-2.
- During the depressurization the crew experienced some complications and indications of upper head voiding are now present.
- STA reports a valid CFST YELLOW path exists on Coolant Inventory.
- The TSC recommends initiating EOP-FRCI-3, Response to Void in Reactor Vessel.
Initiating Cue:
- You are the extra NCO.
- The crew has completed actions in EOP-FRCI-3 up to step 19.1 and has directed you to PERFORM Attachment 1 of EOP-FRCI-3 to determine the maximum venting time.
- The following conditions exist in Unit 2 containment:
- Containment temperature is 140 F
- Containment hydrogen concentration is 1.8%
- RCS pressure is 1200 psig
- Round off to the nearest tenths when performing your calculations
Time-Critical: No
Alternate Path: No
Estimated Time: 8 minutes
Initial Conditions:
- Unit 2 has experienced a small break LOCA.
- The crew has performed an RCS cooldown and depressurization in EOP-LOCA-2.
- During the depressurization the crew experienced some complications and indications of upper head voiding are now present.
- STA reports a valid CFST YELLOW path exists on Coolant Inventory.
- The TSC recommends initiating EOP-FRCI-3, Response to Void in Reactor Vessel.
Initiating Cue:
- You are the extra NCO.
- The crew has completed actions in EOP-FRCI-3 up to step 19.1 and has directed you to PERFORM Attachment 1 of EOP-FRCI-3 to determine the maximum venting time.
- The following conditions exist in Unit 2 containment:
- Containment temperature is 140 F
- Containment hydrogen concentration is 1.8%
- RCS pressure is 1200 psig
- Round off to the nearest tenths when performing your calculations
Task Standard:
1. Correctly performs calculations IAW EOP-FRCI-3, Attachment 1.
2. Calculates Maximum Venting Time of 10.2 mins (9.2 - 11.2 mins acceptable band).
1. Correctly performs calculations IAW EOP-FRCI-3, Attachment 1.
2. Calculates Maximum Venting Time of 10.2 mins (9.2 - 11.2 mins acceptable band).
▶ Show Critical Steps & Key Actions
| Step | Critical Element | Standard |
|---|---|---|
| 1 | Record data from initial conditions (containment temp, H2 concentration, RCS pressure) | Records provided data in steps 1.1 through 1.3 |
| 2.1 * | Calculate containment absolute temperature (Tabs) | Tabs = 140 + 460 = 600 R |
| 2.2 * | Calculate containment air volume (V) at STP | V = 1.28E09 / 600 = 2.13E06 ft3 (2133333 ft3 acceptable with rounding) |
| 3.3 * | Calculate maximum hydrogen vent volume (M) | M = (3% - 1.8%) x 2.13E06 / 100% = 25560 ft3 (25500 to 25600 ft3 acceptable band) |
| 4.1 | Record RCS pressure from step 1.3 | Records 1200 psig |
| 4.2 | Record calculated maximum vent volume (M) from step 3.3 | Records M = 25560 ft3 |
| 4.3 * | Determine hydrogen vent flow rate from Figure 1 at 1200 psig | Using Figure 1, determines Hydrogen Flow Rate of 2500 cfm (+/- 100 cfm readability allowance) |
| 4.4 * | Calculate maximum vent time (Tv) | Tv = 25560 / 2500 = 10.2 mins (+/- 1.0 mins; 9.2 - 11.2 mins acceptable) |
Key Decision Point:
Steps 4.3 and 4.4 are the discriminating steps. The applicant must correctly read the Hydrogen Flow Rate from Figure 1 at 1200 psig RCS pressure (2500 cfm). The graph has readability challenges, so a +/- 100 cfm allowance is factored into the acceptable vent time band. The V calculation formula in this revision uses V = 1.28E09 / Tabs (differs from the 2022 version which uses V = 2.62E06 x Tfact). Due to rounding in intermediate steps, the acceptable vent time band is wide (9.2 - 11.2 mins). Rounding should only be applied to the nearest tenths at the final vent time calculation.
Steps 4.3 and 4.4 are the discriminating steps. The applicant must correctly read the Hydrogen Flow Rate from Figure 1 at 1200 psig RCS pressure (2500 cfm). The graph has readability challenges, so a +/- 100 cfm allowance is factored into the acceptable vent time band. The V calculation formula in this revision uses V = 1.28E09 / Tabs (differs from the 2022 version which uses V = 2.62E06 x Tfact). Due to rounding in intermediate steps, the acceptable vent time band is wide (9.2 - 11.2 mins). Rounding should only be applied to the nearest tenths at the final vent time calculation.
Ref: 2-EOP-FRCI-3 (Rev 30) | Task: N1150880502 | K/A: G2.1.25 — Ability to interpret reference materials, such as graphs, curves, tables | Source: New (Rev 01) | View JPM PDF
Connections
- Related systems: RCS, Containment
- Related EOPs: EOP-FRCI-3 — Response to Void in Reactor Vessel, EOP-LOCA-2 — Post LOCA Cooldown and Depressurization
- Related exam: 2019 NRC Operating Exam