ML23325A017
| ML23325A017 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 05/31/2023 |
| From: | Jack Giessner NRC/RGN-III/DORS/OB |
| To: | Constellation Energy Generation |
| Travis Iskierka-Boggs | |
| Shared Package | |
| 22122A028 | List: |
| References | |
| Download: ML23325A017 (1) | |
Text
Form 3.3-1 Scenario Outline Facility:
Byron Station Scenario #:
N23-1 Scenario Source:
New Op. Test #:
2023-301 Examiners:
Applicants/
Operators:
Initial Conditions:
(IC 73) 54% RTP, MOL, steady state conditions Turnover:
Initiate Containment Vent Release per BCB 400-ECNMT/ROUTINE.
Ramp the unit up to 64% power at 1.6 MW/Min. U0-CC Pump, 1A MFW PP and 1A HD PP OOS.
Critical Tasks:
CT Manually Trip the reactor prior to Initiating Emergency Boration in 1BFR-S.1 CT Transfer to cold leg recirculation prior to reaching 5% in the RWST CT Close containment minipurge isolation valves prior to reporting completion of 1BEP-0 Attachment B Event No.
Malf. No.
Event Type*
Event Description 1
None N
(BOP, US)
Initiate Containment Vent Release per BCB 400-ECNMT/ROUTINE 2
None R
Ramp up 120MW at 1.6 MW/Min per 1BGP 100-3 3
CC01B CC01A C, TS, MC (BOP, US) 1B CC Pump Trip 1A CC Pump does not auto start 4
ZDI1CC685 OPEN YP:MCC07A TRUE YPXMCC07A=125 C, TS, MC (BOP, US) 1A RCP thermal barrier leak into CC 1CC685 does not close in manual or auto 5
PN1932 ON C,US (ATC)
PZR Control Group C SCR firing circuit error (BAR 1-12-C5, PZR PHASE LOSS OR REVERSAL) 6 CV07A C, MC (ATC, US)
Inadvertent Turbine Trip without an automatic RX Trip - 1st manual reactor trip switch does not work 7
[CT]
TH06A 540000 M
LOCA in containment (ES 1.3) 8
[CT]
Smart Scenario Loop C
Fail signal to trip 1VQ05A/B/C
- (N)ormal, (R)eactivity, (I)nstrument, (C)omponent, (M)ajor, (TS)Tech Spec, (MC)Manual Control
Critical Tasks:
CT-01: Manually Trip the reactor prior to Initiating Emergency Boration in 1BFR-S.1 (K/A number -
Reactor Trip EPE007-EA2.02; importance 4.3/4.4)
Safety Significance: Failure to manually trip the reactor causes a challenge to the subcriticality CSF beyond that irreparably introduced by the postulated conditions. Additionally, it constitutes an incorrect performance that necessitates the crew taking compensating action that would complicate the event mitigation strategy and demonstrates the inability of the crew to recognize a failure or an incorrect automatic action of an ESF system or component.
Cues: Red First Out Indication for Turbine Trip above P-8 Performance Indicator: Manipulation of manual reactor trip switches resulting in a reactor trip.
Feedback: All rod bottom lights lit, Reactor Trip and Bypass breakers open and Neutron Flux dropping.
CT-36: Transfer to cold leg recirculation prior to reaching 5% in the RWST. (K/A Number - ECCS 006-A4.07, Importance - 4.4/4.4)
Safety Significance: Improper performance or omission by an operator will result in direct adverse consequence(s) or a significant degradation in the mitigative capability of the plant. Correct performance prevents unnecessary challenges to the CSFs of Core cooling and Containment Cues: Indication and/or annunciation that safety injection is actuated AND Indication and/or annunciation that RWST level is at or below 46.7% AND Indication that containment sump level is at or above the minimum level required for transfer to cold leg recirculation.
Performance Indicator: Manipulation of controls as required to transfer to cold leg recirculation and establish ECCS recirculation flow: Valve position indication that the cold leg recirculation flow path is established and Control switch indication that the circuit breakers or contactors for the low-head injection pumps (and other ECCS injection pumps as necessary) are closed Feedback: Flow indication of the recirculation of containment sump water through the RHR heat exchangers and into the RCS.
CT-14: Close containment minipurge isolation valves prior to reporting completion of 1BEP-0 Attachment B (K/A number - Containment System 103-A3.01; importance 3.9/4.2)
Safety Significance: Closing at least one containment isolation valve on each critical Phase A penetration, under the postulated plant conditions constitutes a task that is essential to safety, because its improper performance or omission by an operator will result in direct adverse consequences or significant degradation in the mitigative capability of the plant. In particular, the crew has failed to prevent degradation of any barrier to fission product release. In this case, the containment barrier is needlessly left in a degraded condition.
Cues: Indication that an automatic isolation of a containment release did not occur with a primary system break in containment and rising radiation levels on 1PR01J, Containment Purge Effluent as well as 1PR28J and 1PR30J, Aux Building Vent Stacks, indicating an uncontrolled release is
in progress.
Performance Indicator: Manipulation of controls as required to close at least one containment isolation valve to stop the containment release.
Feedback: ESF system status lamps, or valve position indication on 0PM02J, that at least one containment isolation valve is closed.
Scenario 23-1 Summary The scenario will start with Unit 1 at 54% power, MOL, steady state conditions. The crew will be turned over the activity to perform a containment release per BCB 400-ECNMT/ROUTINE.
Crew will be directed to ramp the unit up 120 MW at 1.6 MW/Min. U0-CC Pump, 1A MFW PP and 1A HD PP OOS.
Event 1 Initiate Containment Vent Release per BCB 400-ECNMT/ROUTINE The crew will Initiate a Containment Vent Release per BCB 400-ECNMT/ROUTINE.
Performance steps will be from BOP VQ-6 step F.4 Event 2 Ramp up 120MW at 1.6 MW/Min per 1BGP 100-3 As directed by the turnover, the crew will initiate a ramp up 120MW power at 1.6 MW/Min. The crew will hold a reactivity brief to review material prepared prior to the beginning of the scenario.
The crew will ramp per 1BGP 100-3. After the ramp is initiated and sufficient reactivity maneuvering is observed, and at the lead examiner discretion, continue on with Event 3.
Event 3 1B CC Pump Trip - 1A CC Pump does not auto start The crew will manually start the 1A CC pump per BAR 1-2-A4 CC PUMP TRIP or OP-AA-103-102-1001 STRATEGIES FOR SUCCESSFUL TRANSIENT MITIGATION. The crew will enter Tech Spec 3.7.7 Condition B. Once alarms are clear and system parameters are stable, at the lead examiner discretion, continue to Event 4.
Event 4 1A RCP seal leak into CC will require the isolation of CC to all RCP thermal barriers (1CC685 fails to close in auto/manual)
The crew will receive radiation alarms in the CC system and will recognize CC tank level rising.
Crew will enter 1BOA PRI-6, COMPONENT COOLING MALFUNCTION to address the leakage.
Crew will identify abnormal seal injection flow and 1CC685 did not auto close as expected.
Crew will attempt to close 1CC685 and, when unsuccessful, be directed to close 1CC9438 isolating all component cooling flow to the RCP thermal barriers (RCP oil coolers will remain unaffected). The SRO will enter TS 3.6.3 Condition A for containment isolation valve 1CC685 and request direction of the SM to restore barrier flow to the unaffected RCPs, which will be delayed with a duty team challenge and plan development. Once the crew has stabilized and recovered the CC system, at the lead examiner discretion, continue on to Event 5.
Event 5 PZR Control Group C SCR firing circuit error The crew will respond to alarm 1-12-C5, PZR PHASE LOSS OR REVERSAL. ATC will energize pressurizer back up heaters and trip group C variable heaters allowing spray to maintain pressure control. At lead examiner discretion, once pressure control has been established, continue to Event 6.
Event 6 Inadvertent Turbine Trip without an automatic RX Trip - 1st manual reactor trip switch does not work Crew will respond to 1-11-A9, Turbine Trip Above P8 RX Trip, and recognize the turbine trip signal is valid and the reactor failed to trip on interlock. The first RX trip switch selected by the ATC will not work and use of the second switch will be required. Tripping the reactor will automatically transition the crew to Event 7.
Event 7 & 8: LOCA (ES 1.3) - Containment venting does not auto isolate The reactor trip will trigger a large break LOCA. The crew will enter 1BEP-0 and perform immediate actions. The crew will identify an automatic SI occurred and the BOP will be
dispatched with Attachment B to identify that the containment vent path did not auto isolate. The crew will transition to 1BEP-1 and then to 1BEP ES-1.3 to establish cold leg recirculation. The scenario is complete when the crew has completed step 10 of 1 BEP ES-1.3 establishing cold leg recirculation and with the concurrence of the lead examiner.
Form 3.3-1 Scenario Outline Facility:
Byron Station Scenario #:
N23-2 Scenario Source:
Op. Test #:
2023-301 Examiners:
Applicants/
Operators:
Initial Conditions:
(IC79) 28% RTP, MOL, steady state conditions Turnover:
Swap bus 156 from the UAT to the SAT to establish a shutdown electrical lineup per BOP AP-200 step F2. Ramp the unit down 40 MW per 1BGP 100-4. 1A HD pump tripped and OOS for repairs. The 0G SX fan and 0H SX fan are OOS.
Critical Tasks:
CT Manually control AF flowrate to not less than 45 gpm per intact SG to minimize the RCS cooldown rate before a severe (Orange path) challenge develops to the integrity CSF CT-9 - Manually start SX pumps for safeguards equipment cooling prior to exiting EP-0 Event No.
Malf. No.
Event Type*
Event Description ZDI1AF01PB STOP FW43 Preload 1B AF PP will not automatically start but can be manually started 1A AF PP auto starts and trips after 5 seconds 1
None N
(BOP, US)
Swap bus 156 from UAT to the SAT 2
None R
Ramp down 40 MW at 1.6 MW/min per 1BGP 100-4 3
ZDI1CV110B C, MC (ATC, US) 1CV110B, Boric Acid Blender to Charging Pumps valve fails closed 4
PN1100 ON TS (US)
CNMT Hatch door Seal Supply Air Press alarm 5
PA0153 C, MC, TS (BOP, US)
SX cooling fan vibration alarm 6
ZDI1CV8401A CLS C, US (ATC) 1CV8401B, 1B letdown HX inlet valve, failed closed 7
FW02A/B C
(BOP, US)
Only running TDFW PP (1B) trips, manual start of the 1A MDFW PP 8
MS08A 4 M
(ATC, BOP, US) 1A SG Fault, inside containment, inserted when the 1A MDFW PP is manually started or if the plant trips.
(EP-2) 9
[CT-33]
MS01A-D C
All MSIVs fail to close and can not be manually closed. (CA 2.1)
10
[CT-9]
C 1A SX PP trips and 1B SX PP fails to autostart
- (N)ormal, (R)eactivity, (I)nstrument, (C)omponent, (M)ajor, (TS)Tech Spec, (MC)Manual Control
Critical Tasks:
CT-33: Manually control AF flowrate to not less than 45 gpm per intact SG to minimize the RCS cooldown rate before a severe (Orange path) challenge develops to the integrity CSF (K/A Number - SF4P 035-A2.01, Importance 4.6/4.4)
Safety Significance: Improper performance or omission by an operator will result in direct adverse consequence(s) or a significant degradation in the mitigative capability of the plant.
Correct performance prevents unnecessary challenges to the CSFs of Integrity and Subcriticality.
Cues: Indication of uncontrolled depressurization of all SGs, Indication that the RCS cold leg cooldown rate exceeds 100F per hour and flow rate indication that AFW continues to be delivered to the faulted SGs above the rate required in CA 2.1 Performance Indicator: Manipulation of controls as required to throttle the AFW flow rate sufficiently to prevent an Orange path CSF but not less than that required by CA 2.1 Feedback: RCS cooldown stops and an Orange path CSF is not identified.
CT-9: Manually start SW pumps for safeguards equipment cooling prior to exiting EP-0 (K/A Number SWS 076-A2.03, Importance 3.9 / 3.7)
Safety Significance: Failure to manually start at least the minimum required number of SW pumps in an operating safeguards train will result in damage to any running diesel generators resulting in the inability to maintain long term core cooling during a loss of offsite power. Section 8.3-24a of the UFSAR states the diesel generator was designed to operator for 5 minutes without a supply of cooling water. When tested on the simulator under full load, the diesels failed around 10 minutes under full load with no essential cooling water. As expected, further modeling demonstrated that the time to trip was inversely related to diesel loading and an unloaded diesel was able to run for >30 minutes. Additionally, SX flow is required for long term plant cooling and is both required an assumed in most engineered safety function calculations. The importance of SX, along with the relatively short period of time in which unrecoverable damage would occur to the diesel generators justifies actions to restore be complete prior to exiting EP-0 Cues: Indication and/or annunciation that SI is actuated AND Indication [and/or annunciation] that less than the minimum required number of SW pumps is running Performance Indicator: Manipulation of controls as required to start at least the minimum required number of SW pumps in an operating safeguards train for ESF equipment in operation.
Feedback: Indication and/or annunciation that at least the minimum required number of SW pumps is running in an operating safeguards train o
SW low flow condition clear; indication of flow o
SW low pressure condition clear; indication of pressure.
Scenario 23-2 Summary The scenario will start with at 28% power, MOL, steady state conditions. The crew will be turned over the activity to perform a power supply swap for bus 156. Crew will be directed to ramp the unit down 40 MW per BGP 100-4 and will be provided a turnover of BGP 100-4T1 showing all required items are complete through 30% power with the next required actions occurring when they hold at 25%. 1A HD pump OOS is for overall issue consistency and does not impact this scenario.
Event 1 Swap bus 156 from the UAT to the SAT The crew will perform a swap of bus 156 from the UAT to the SAT using BOP AP-200 step F2.
Event 2 Ramp down 40 MW at 1.6 MW/min As directed by the turnover, the crew will initiate a ramp down 40 MW at 1.6 MW/min per BGP 100-4 and will be provided a marked up copy of BGP 100-4T1 showing all required items are complete through 30% power with the next required actions occurring when they hold around 25%. After the ramp is initiated and sufficient reactivity maneuvering is observed, and at the lead examiner discretion, continue on with Event 3.
Event 3 1CV110B Boric Acid Blender to Charging Pumps valve fails to open During boration operations, the 1CV110B Boric Acid Blender to Charging Pumps valve will fail to open as identified by valve position and Annunciator 1-9-A6 BA FLOW DEVIATION. The ATC will identify the lack of boration flow, reference the BAR, and manually open 1CV110B to initiate boration flow. Once boration flow is established, at the lead examiners discretion, continue to Event 4.
Event 4 CNMT Hatch Door Seal Supply Air Press alarm The crew will respond to annunciator 1-1-B2, CNMT HATCH DOOR SEAL TROUBLE. The crew will dispatch an operator to investigate. Air lock supply air pressure will be reported low and, if asked, will report that air can be felt blowing by the outer door gasket. Tech Spec 3.6.2 condition A will be entered.
Event 5 SX cooling fan vibration alarm The crew will respond to alarm 0-37-E6, SX CLG TWR FAN VIBRATION HIGH. The BOP will identify abnormally high fan amps and will trip the 0F SX fan. The 0G SX fan and 0H SX fan are OOS requiring the SRO to identify and enter Tech Spec 3.7.9 condition B. Once the crew has evaluated cooling continue on to Event 6.
Event 6 1CV8401B, 1B letdown HX inlet valve, failed closed The crew will identify 1CV8401B, 1B letdown HX inlet valve, failed closed resulting in the isolation of letdown flow. The crew will respond to the malfunction and will complete letdown isolation per 1BHC 1-LD. The crew will restore letdown flow through the 1A letdown HX using BOP CV-22 and BOP CV-17. The crew may enter Tech Spec 3.4.13 Cond A for identified leakage depending on severity/duration if 1CV8117, Letdown Line Relief Vlv lifts. Once letdown or excess letdown has been established, continue to Event 7.
Event 7 Running TDFW PP Trip (MDFW PP Start or Rx Trip will start the 1A SG Fault after a 20 second time delay)
The 1B TDFW PP will trip and the crew will respond with BHC 1-16-BC1 to start the 1A MDFW PP.
Event 8 1A SG Fault
Starting the 1A MDFW PP or a reactor trip (auto or manual) will start an automatic 20 second timer before inputting a 1A SG Fault inside containment. Fault will result in a Reactor Trip and Safety Injection. 1A SX PP will Trip and the 1B SX PP will not autostart. Crew will enter 1BEP-0 and transition to 1BEP-2.
Event 9 All MSIVs stuck open Crew will transition from 1BEP-2 to 1BCA-2.1, UNCONTROLLED DEPRESSURIZATION OF ALL STEAM GENERATORS. The crew will adjust AF flow to control the cooldown of the RCS to eliminate the risk of brittle fracture. All MSIVs will indicate intermediate and after flow to the 1C SG is throttled down to about 50 gpm, the 1D MSIV will finally drift all the way closed allowing the crew to use the 1BCA-2.1 OAS actions and provide a path to recovery via 1BEP-2.
Form 3.3-1 Scenario Outline Facility:
Byron Station Scenario #:
N23-3 Scenario Source:
New Op. Test #:
2023-301 Examiners:
Applicants/
Operators:
Initial Conditions:
(IC 71) 100% RTP, MOL, steady state conditions Turnover:
U-2 is in mode 5 in preparation for refueling outage B2R24. 1BOSR FW-M1 is scheduled to be performed early on this shift. Unit 2 will be doing a test run of the 2B DG to confirm post maintenance operability.
Critical Tasks:
CT-4 - Establish AFW flow to SGs before a CSF red path develops for Heat Sink CT Energize at least one AC emergency bus within 10 minutes of a Loss of ALL AC per UFSAR Event No.
Malf. No.
Event Type*
Event Description 1
None N
(BOP, US) 1BOSR FW-M1 2
NI09C TS, I
( US, BOP )
N-43 fails low 3
FW22D FW22A C, MC (BOP,US) 1A CD/CB PP trip 1D CD/CB PP will not auto start 4
IMF RX15inc RAISE I, MC (ATC,US)
Master PZR pressure controller fails high 5
CH08B 10 TS (US)
Containment pressure 1PT-CS935 fails to 10 PSIG 6
FW22B R
1B CD/CB PP Trips requiring a runback 7
RD06 C, MC (ATC,US)
Rods will not move in automatic Rods WILL move in manual 8
ED02C ED02D M
LOOP/Unit Trip 1B DG Fails to start 9
[CT]
FW43 C
Loss of 1A DG 10
[CT]
ED24A C
Bus 141 fault, feed breaker trips, transition to BCA 0.0
- (N)ormal, (R)eactivity, (I)nstrument, (C)omponent, (M)ajor, (TS)Tech Spec, (MC)Manual Control
Critical Tasks:
CT-4: Establish AFW flow to SGs before a CSF red path develops for Heat Sink (K/A Number - AFW 021-A3.01, Importance 4.2)
Safety Significance: Failure to establish feed flow to the generators would result in the need for 1BFR H.1, RESPONSE TO LOSS OF SECONDARY HEAT SINK UNIT 1. This process would needlessly challenge the primary RCS boundary both in the steam generator and in containment.
Cues: Indication and/or annunciation that SI is actuated AND indication and/or annunciation that AFW flow rate is less than the minimum required Performance Indicator: Indication of minimum of 500 gpm flow to the Steam Generators or Steam Generator level rising.
Feedback: Run indication on the 1B AF PP, indication of forward flow into all SGs and lowering RCS hot leg temperature.
CT-24: Energize at least one AC emergency bus within 10 minutes of a Loss of ALL AC per UFSAR (K/A Number - EPE 055-EA1.06, Importance 4.3)
Safety Significance: The analysis in the UFSAR credits operator action being complete within 10 minutes of a loss of all power event. Failure to complete the required actions in 10 minutes puts the crew outside of the safety analysis and would constitute a failure.
Additionally, failure to energize an ac emergency bus constitutes misoperation or incorrect crew performance in which the crew does not prevent degraded emergency power capacity. Failure to perform the critical task also results in needless degradation of any barrier to fission product release.
Cues: Indication and/or annunciation that both AC emergency buses are de-energized o
Bus energized lamps extinguished o
Circuit breaker position o
Bus voltage o
EDG status Performance Indicator: Indication that at least one AC emergency bus is energized Feedback: Indication that at least one AC emergency bus is energized as indicated by successfully starting Safeguards equipment on the affected unit.
Scenario 23-3 Summary The scenario will start with U-1 at 100% power, MOL, steady state conditions. U-2 is in mode 5 in preparation for refueling outage B2R24. 1BOSR FW-M1 is scheduled to be performed early on this shift. Unit 2 will be doing a test run of the 2B DG to confirm post maintenance operability.
Event 1 1BOSR FW-M1, 1B & 1C TURBINE DRIVEN MAIN FEEDWATER PUMP STOP VALVE MONTHLY SURVEILLANCE The crew will perform 1BOSR FW-M1.
When the surveillance is complete and, with the lead examiners concurrence, continue to Event
- 2.
Event 2 N-43 Fails low The crew will identify the failed NI and respond per 1BOA INST-1, NUCLEAR INSTRUMENTATION MALFUNCTION UNIT 1. The crew will verify the plant is stable and bypass/defeat the PR Channel Functions. The crew will enter LCO 3.3.1 Cond A, D and E.
When the crew has completed actions for N-43 and the rods are back in auto or at the direction of the lead examiner, continue to Event 3.
Event 3 1A CD/CB PP trips and 1D CD/CB PP does not auto start The crew will respond to a trip of the 1A CD/CB PP using BHC 1-17-A9, CD/CB PUMP TRIP and will manually start the 1D CD/CB PP that failed to start in auto. Once the 1D CD/CB PP is running and, at the lead examiners discretion, continue to Event 4.
Event 4 Master PZR pressure controller fails high The SRO will direct the ATC to respond per BHC 1-RY-P. The ATC will place the controller, 1PK-455A, in manual and maintain PZR pressure in the desired band. The ATC will take manual control of the Master PZR pressure controller, or manual control of spray flow and heaters, to restore pressurizer pressure. Once the plant has been stabilized, and with the concurrence of the lead examiner, continue to Event 5.
Event 5 Containment pressure 1PT-CS935 fails to 10 PSIG The crew will respond to high containment alarms 1-3-C4 and D4, CNMT PRESS HI and HI-2.
The crew will recognize the failed instrument and enter 1BOA INST-2, OPERATION WITH A FAILED INSTRUMENT CHANNEL UNIT 1. The SRO will identify and enter Tech Spec 3.3.2 condition A & E. At the direction of the lead examiner, continue with Event 6.
Event 6 CD/FW Runback from the trip of the 1B CD/CB PP The crew will respond to a trip of the 1B CD/CB PP using BHC 1-17-A9, CD/CB PUMP TRIP.
With no other CD/CB PPs to start, the crew will initiate a runback. The crew will enter 1BOA SEC-1. Once the run back is in progress, the rod failure has been addressed (Event 7) and sufficient reactivity manipulations have been observed or the crew manually trips the reactor or at the direction of the lead examiner, continue to Event 8.
Event 7 Rods will not move in automatic Rods will be unable to move in automatic. The ATC will identify and address the rod failure during the CD/FW Runback by taking rods to manual. The crew will enter 1BOA ROD-2, FAILURE OF RODS TO MOVE UNIT 1. Transition to Event 8 per Event 6 direction.
Event 8 & 9 LOOP and reactor trip with 1A DG and 1B AF PP not starting.
A microburst storm event will short out the switchyard resulting in the opening of all Unit 1 yard feeder breakers, 3-4 and 4-5 resulting in a trip of Unit 1. Additionally, ACB 5-6 and OCB 6-7 will trip removing power from the U-1 SATs and a fault will propagate to bus 141. The 1B DG starts but the 1A does not. U1 will enter 1BEP 0. The 1B AF PP will not auto start but can be started from the MCR switch. After the 1B AF PP is started, a 10 second timer will trip the 1B DG and U-1 will enter Event 10.
Event 10 1B DG Trip (1BCA 0.0) 10 seconds after the 1B AF PP is started, the 1B DG will trip and the crew will enter 1BCA 0.0.
Crew will determine that bus 141 is faulted and will change the recovery plan to use bus 142.
The U-2 US will be notified to enter 2BCA 0.3 for bus 142 and the crew must restore power to Unit 1 within 10 minutes. The scenario is complete when the crew successfully cross-ties power from Unit 2 to Unit 1 or at the direction of the Lead Examiner.
Form 3.3-1 Scenario Outline Facility:
Byron Station Scenario #:
N23-4 Scenario Source:
New Op. Test #:
2023-301 Examiners:
Applicants/
Operators:
Initial Conditions:
IC 65 88% RTP, MOL, steady state conditions Turnover:
U-1 is at 88% power, steady state, equilibrium Xenon, MOL. Online risk is green. Following completion of turnover, the Shift Manger has directed the crew to swap the RCFC lineup. The 1A MFP is OOS for an oil change.
Critical Tasks:
CT-13 Manually trip the Turbine before a severe challenge (ORANGE path) develops to either subcriticality or integrity critical safety function.
CT-43 Establish minimum feedwater or condensate flow to SG(s) before bleed and feed is required (Feedwater pump or condensate pump feeding the SGs such that at least two SG levels are maintained above 27% Wide Range)
Event No.
Malf. No.
Event Type*
Event Description 1
None N
(BOP, US)
Swap RCFCs 2
NI09C C, MC, TS (ATC,US)
Inadvertent Phase A (Alpha Train only) 3 NI09C C, MC (BOP) 1A CW PP trip and discharge valve does not auto close 4
RX28G 0 30 TS, C (US) 1C Loop flow (434) fails low 5
C, MC (ATC) 1LT-112 fails high 6
IOR ZDI0PBCW03PA ON R
(US, ATC, BOP) 1A HD (shaft shear) and 1C HD PP will not start requiring a HD runback 7
[CT]
ZDI1CV8401A CLS M, C, (All)
Inadvertent Safety Injection, Reactor and Main Turbine do not trip automatically (1A AF PP starts, 1B AF PP can not be started) 8
[CT]
IMF FW35B C
1A AF Pump trips (BFR H.1)
- (N)ormal, (R)eactivity, (I)nstrument, (C)omponent, (M)ajor, (TS)Tech Spec, (MC)Manual Control SPARE SCENARIO - NOT USED
Critical Tasks:
CT-13: Manually trip the Turbine before a severe challenge (ORANGE path) develops to either subcriticality or integrity critical safety function. (K/A Number - 002-A2.04, Importance 4.5)
Safety Significance: Failure to trip the main turbine under the postulated plant conditions causes challenges to CSFs beyond those irreparably introduced by the postulated conditions.
Cues: Indication and/or annunciation of reactor trip, rod bottom lamps illuminated, reactor trip and bypass breakers status lamps indicate breakers open, excore nuclear instruments show reactor power decreasing through the intermediate range and indication that the main turbine has not automatically tripped, stop valves indicate open, control valves indicate at their full-load position, or indication of uncontrolled depressurization of all SGs.
Performance Indicator: Manipulation of controls to transfer and manually trip the main turbine - stop valves and/or governor valves indicate closed.
Feedback: Steam flow indication from all intact SGs decreases to zero, all SGs stop depressurizing, RCS cooldown from intact SG stops.
CT-43: Establish minimum feedwater or condensate flow to SG(s) before bleed and feed is required (Feedwater pump or condensate pump feeding the SGs such that at least two SG levels are maintained above 27% Wide Range). (K/A Number - E05-EA1.18, Importance 3.8)
Safety Significance: Failure to establish feedwater flow to any SG results in the crews having to rely upon the lower-priority action of establishing RCS bleed and feed to minimize core uncover. This constitutes incorrect performance that fails to prevent degradation of any barrier to fission product release.
Cues: Extreme (RED path) challenges to the heat sink CSF, indication the RCS pressure remains above the pressure of all SGs, indication that RCS temperature is above the temperature for placing the RHR system in service, indication and/or annunciation that no AFW flow if available after repeated attempts to establish and feed/bleed conditions have not been established.
Performance Indicator: Manipulation of controls as required to establish feedwater flow into at least one SG Feedback: Indication of feedwater flow into at least one SG or increasing water level in at least one SG
Scenario 23-4 Summary The scenario will start with U-1 at 88% power, steady state, equilibrium Xenon, MOL. Online risk is green. Following completion of turnover, the Shift Manger is directed to swap the RCFC lineup. The 1A MFP is OOS for an oil change.
Event 1 Swap RCFCs After completing shift turnover and relief, the crew will swap RCFCs per Shift Manager. The BOP will start the 1B RCFC and secure the 1D RCFC.
Event 2 Inadvertent Phase A (A Train only)
The crew will identify a Train A spurious phase A actuation and respond using 1BOA PRI-13.
The crew will take manual control of charging to minimize pressurizer level rise and will start available RCFCs in high speed. US will enter 3.3.2 Condition A and C. Continue to Event 3 after the crew has completed 1BOA PRI-13 and notifications have been made or at the direction of the lead examiner.
Event 3 1A CW PP trip and discharge valve does not auto close 1A CW PP will trip and the BOP will respond to alarm 1-17-A13. The BOP will identify the discharge valve is not intermediate (not closing) and will need to manually close the valve.
Continue to Event 5 once the discharge valve has been closed and condenser vacuum is trending toward normal or at the direction of the lead examiner.
Event 4 1C Loop flow 434 fails low 1FT434, 1C RCS Flow Loop Transmitter, fails low and 1-13-C3 will alarm. The crew will determine that a channel failure has occurred and implement 1BOA INST-2, OPERATION WITH A FAILED INSTRUMENT CHANNEL UNIT 1, Attachment L. Tech Spec 3.3.1 Condition A & K will be entered.
Event 5 1LT-112 fails high 1LT-112 will fail high. This will cause 1-19-D2, LTDWN FLOW DIVERTED TO HUT alarm and letdown flow will divert to the HUT. The Bar will direct the crew to 1BOA INST-2 and, depending on how the BAR is utilized, will direct the ATC to maintain VCT level. The ATC should identify the failed instrument and take manual control to reposition 1CV112A to the VCT Position to stop the VCT level loss. The first step of 1BOA INST-2 will give similar guidance to maintain VCT level manually. This event is complete when the ATC has taken a manual action to maintain VCT level and an operable channel has been selected.
Event 6 1A HD (shaft shear) and 1C HD PP can not be started requiring a HD runback The crew will respond to a low FW PP suction pressure condition (which may clear temporarily when the standby CD/CB PP starts) or the HD train tank Hi level alarm. They will identify that the 1A HD pump is running but drawing no amps and pushing no flow. They will further identify that the 1C HD PP did not start as anticipated, can not be manually started and that a HD run back is required.
Event 7 Inadvertent Safety Injection, Reactor and Main Turbine do not trip automatically (1A AF PP starts, 1B AF PP can not be started)
An inadvertent Safety Injection signal will occur. The reactor will not trip and the crew enter 1BEP-0. During immediate actions, the ATC will trip the reactor using the manual trip switch and the BOP will identify that the turbine did not trip and will have to manually trip the turbine. The
1B AF pump will not have auto started and can not be manually started. The 1A AF Pump will auto start.
Event 8 1A AF Pump trips (BFR H.1) 10 seconds after the reactor trip, the 1A AF PP will trip resulting in the loss of the secondary heat sink. The crew will transition to BFR H.1 from 1BEP 0 step 6. The recovery path will be through the use of the startup feedwater pump. The Scenario may be terminated after the SU FW PP is running, flow to at least one SG has been initiated, applicable SG level(s) are trending up and CETCs are trending down or at the direction of the lead examiner.
Form 3.3-1 Scenario Outline Facility:
Byron Station Scenario #:
N23-5 Scenario Source:
New Op. Test #:
2023-301 Examiners:
Applicants/
Operators:
Initial Conditions:
IC 70 10% RTP, BOL, steady state conditions Turnover:
U-1 is 10%, BOL, equilibrium xenon and steady state conditions.
Following the completion of turnover, place the Reheat Temperature Controller in AUTO per 1BGP 100-3 step 5 and then vent the PRT to GW per BOP RY-3 step F.1. 1A MFP, 1D CD/CB and U0 CC PP are OOS for oil changes.
Critical Tasks:
CT Manually actuate Main Steamline Isolation before an orange path CSF in integrity occurs CT Isolate the faulted SG before an orange path CSF in integrity occurs Event No.
Malf. No.
Event Type*
Event Description 1
None N
(BOP)
Place Reheat Temperature Controller in AUTO 2
TH18E C, MC (ATC)
Vent PRT to GW system, PRT PRESS HIGH Alarm, 1RY469 does not auto CLOSE 3
Earthquake Code IMF TH04B 20 120 TS (US)
Seismic Event 4
Earthquake Code ZDI0PBCW03PA I, TS (BOP,US)
Aftershock results in 1LT558 (1C SG Level Channel) failing low 5
IMF ED10B IMF ED11B I, TS (BOP,ATC,US)
Trip of Instrument Bus 112 6
ZDI1CV8401A CLS C
(ATC)
Trip 1B RCP and Manual Reactor Trip 7
[CT-12]
IMF FW35B M
Large earthquake results in 1B SG Fault inside containment (BEP-2) 8
[CT-17]
TH11B C
MSIVs fail to close in auto but will close at MSI switch or each individual valve switch.
- (N)ormal, (R)eactivity, (I)nstrument, (C)omponent, (M)ajor, (TS)Tech Spec, (MC)Manual Control SPARE SCENARIO - NOT USED
Critical Tasks:
CT-12: Manually actuate Main Steamline Isolation before an orange path CSF in integrity occurs (K/A: EPE 040AA1.01; importance - 4.3)
Safety Significance: Failure to isolate uncontrolled steam flow from multiple SGs can result in challenges to the CSFs Integrity, Subcriticality, and Containment.
Cues: Indication that a main steam line isolation is required and indication that an automatic main Steamline isolation did not occur.
Performance Indicator: Manually actuate main steam line isolation before meeting conditions to enter 1BFR S.1 Response to Nuclear Power Generation (Intermediate Range SUR positive) or 1BFR P.1 Response to Imminent Pressurized Thermal Shock Condition (temperature drop of greater than 100°F in ALL RCS Cold Legs and ALL RCS Cold Legs less than 240°F).
Feedback: Open MSIVs indicate closed due to manual action.
CT-17: Isolate the faulted SG before an orange path CSF in integrity occurs (K/A number - APE 040-AA1.03 importance 3.9)
Safety Significance: Failure to isolate a faulted SG can result in challenges to the CSFs Integrity, Subcriticality, and Containment.
Cues: Steam pressure and flow rate indications that make it possible to identify a single SG as faulted AND valve position and flow rate indication that AFW continues to be delivered to the faulted SG.
Performance Indicator: Isolate the faulted 1B SG before transition out of 1BEP-2.
Feedback: Manipulate controls to isolate the faulted the SG by MSIVs indicate closed, feedline isolation valves closed, and indication of AFW flow to the faulted SG is stopped.
Scenario 23-5 Summary U-1 is 10%, BOL, equilibrium xenon and steady state conditions. Following the completion of turnover, place the Reheat Temperature Controller in AUTO per 1BGP 100-3 step 5 then vent the PRT to the GW system per BOP RY-3 step F.1. The 1A MFP, 1D CD/CB and U0 CC PP are OOS for overall scenario consistency and does not impact the scenario.
Event 1 Place Reheat Temperature Controller in AUTO The crew will place the Reheat Temperature Controller (RTC) in AUTO per step F.5 of 1BGP 100-3, POWER ASCENSION When the RTC controller is in auto and the remaining steps are EO field steps, the crew will be prompted, if needed, by the SM to vent the PRT per the turnover. With the concurrence of the lead examiner, continue to Event 2.
Event 2 Vent PRT to GW system, PRT PRESS HIGH Alarm, 1RY469 does not auto CLOSE The crew will use BOP RY-3, FILLING AND VENTING THE PRESSURIZER RELIEF TANK to lower PRT pressure from 5.6 PSIG to 3 PSIG per the turnover. The Nitrogen regulator will fail high 5 seconds after the 1RY469 is opened. Alarm 1-12-B7, PRT PRESS HIGH will come in about 20 seconds later and 1RY469 will NOT auto close. The ATC will manually close 1RY469 per the BAR and will close 1RY8030 per the BAR actions to isolate the PRT from the N2 regulator. Once the SM has been updated on the evolution and valve failure, and, at the lead examiners discretion, continue to Event 3.
Event 3 Seismic Event Annunciators 0-38-E5, ACCCELEROGRAPGH ACCEL HIGH, 1-13-E9, LOOSE PARTS MONITORING SYSTEM TROUBLE, and 1-18-D13, H2/STATOR CLG PANEL TROUBLE will be received. The crew will implement 0BOA ENV-4, Earthquake Unit 0A report from the TR operator will be received reporting that he felt the ground shaking. The crew will implement 0BOA ENV-4, Earthquake Unit 0, determine that a seismic event has occurred and enter TRM 3.3.b Condition C.
Event 4 Aftershock results in 1LT558 (1A SG Level Channel) failing low A small aftershock will occur and 1LT558 will fail low. The crew will implement 1BOA INST-2, OPERATION WITH A FAILED INSTRUMENT CHANNEL, Attachment E. Tech Spec 3.3.1 conditions A and E and Tech Spec 3.3.2 conditions A and D will be entered. After the T.S. call has been made, and with the concurrence of the lead examiner, continue to Event 6.
Event 5 Trip of Instrument Bus 112 Instrument Bus 112 and CVT will fail. This will cause a loss of Instrument Bus 112. The crew will identify the loss and respond using 1BOA ELEC-2 LOSS OF INSTRUMENT BUS UNIT 1.
Report from the field will indicate damage to the bus. The crew will use 1BOA ELEC-2 LOSS OF INSTRUMENT BUS UNIT 1 Attachment B to respond to the failure. 1BOA INST-1 NUCLEAR INSTRUMENTATION MALFUNCTION will be used to respond to the loss of N42.
This will place control rods in manual, remove N42 from service in the PPC, and align bypass and defeat switches for the defeated PR channel. Once Instrument Bus 112 has been addressed, T.S. determined and with the concurrence of the lead examiner, continue to Event 6.
Event 6 Trip 1B RCP The aftershock from Event 4, also caused a slight shaft misalignment in the 1B RCP resulting in 1B RCP breaker trip. Annunciator 1-13-B3, RCP 1B BRKR OPEN OR FLOW LOW ALERT, will alarm when loop flow drops to 90%. Because reactor power is below P-8, an automatic reactor trip will not occur. The crew will identify 1B RCP trip and the US will order a manual trip of U-1.
Once the crew works through the immediate actions of 1BEP-0, a final earthquake will be felt resulting in events 7 & 8.
Event 7 Large earthquake results in 1B SG Fault inside containment (BEP-2)
A steam line break will occur on 1B SG inside of CNMT. The crew will re-enter 1BEP-0, REACTOR TRIP OR SAFETY INJECTION. The crew will initiate a manual Safety Injection, if an automatic one has not occurred. The Crew will transition to 1BEP-2 FAULTED STEAM GENERATOR ISOLATION. The scenario is complete when the crew has transitioned from 1BEP-2 to either 1BEP ES-1.1 SI TERMINATION UNIT 1 or 1BEP-1 LOSS OF REACTOR OR SECONDARY COOLING, the 1B SG is isolated and with the lead evaluators concurrence.
Event 8 MSIVs fail to close in auto but will close with either of the Main Steam Isolate switches or the individual valve control switches The crew will identify that the MS Isolation valves failed to close in automatic and initiate a MS Isolation via either MCB control switch (or take each MSIV switch to close).