40EP-9EO05 Excess Steam Demand (ESD)

Question 1

What is the mitigating strategy for 40EP-9EO05 Excess Steam Demand (ESD)?

Answer 1

• Isolating affected SG
• Stabilize RCS Temperature
• Throttle HPSI
• Control RCS Heat Removal with good SG
• Once stable determine if C/D will be performed

Question 2

What are indications of an Excess Steam Demand (ESD)

Answer 2

• Stuck Open MSSV/ ADV
• ↓ RCS temp (SLB)
• ↑ RCS Temp (FLB)
• ↑ MFW flow (until FWIV close)

Break in CNTMT: CNTMT T, P, Humidity, sump level ↑

Question 3

In regards to Indications in containment, what are the major differences between a LOCA and an ESD?

Answer 3

• Subcooling Margin

- Radiation

Question 4

What are the branching paths for an ESD that is isolated in SPTA’s

Answer 4

• Tc > 560°F either ESD or RT EOP ok

- Tc < 560°F ESD EOP only

Question 5

For 40EP-9EO05 Excess Steam Demand (ESD), What is the Largest Possible MSLB?
What design element is used to lessen its effect?

Answer 5

• Double ended guillotine break upstream of MSIV’s

- Venturi flow restrictors in SG outlet nozzles - limits max blowdown rate

Question 6

During 40EP-9EO05 Excess Steam Demand (ESD) the safety analysis does NOT credit operator action until when?

Answer 6

• No operator action until 30 MINUTES

Question 7

For a Excess Steam Demand (ESD), what is the most limiting single failure and why?

Answer 7

• Failure if 1 HPSI to start
• Reduces SI ability for adding boron to core
• Increases potential to return to criticality

Question 8

For 40EP-9EO05 Excess Steam Demand (ESD), the Reactivity Control SFSC is

Answer 8

• < 2 X10-4% ↔ or ↓

- All FSCEA inserted OR > 40gpm boration OR SDM verified

Question 9

For 40EP-9EO05 Excess Steam Demand (ESD), the maintenance of Vital Auxiliaries SFSC is

Answer 9

• At least 1 PB
• PKA/PKC/PNA or PKB/PKD/PNB on same train as PB
• Bus Plus

Question 10

For 40EP-9EO05 Excess Steam Demand (ESD), the TCS Inventory Control SFSC is

Answer 10

Condition 1:

• Lpzr > 10% [15]
• ≥ 24°F [44] RCS Subcooling
• RVUH ≥ 16%
• SI Flow not needed after Throttle criteria met

Condition 2:

• SI Flow Adequate
• RVLMS outlet plenum ≥ 21%

Question 11

For 40EP-9EO05 Excess Steam Demand (ESD), the RCS Pressure Control SFSC is

Answer 11

Condition 1:
- P/T limit

Condition 2:
- SI Flow Adequate

Question 12

For 40EP-9EO05 Excess Steam Demand (ESD), the Core Heat Removal SFSC is

Answer 12

• Th < 650°F
• Max CET < 650°F
• ≥ 24°F [44] RCS Subcooling

Question 13

For 40EP-9EO05 Excess Steam Demand (ESD), the RCS Heat Removal SFSC is

Answer 13

• Unisolated SG 45-60% NR or restoring to

- Tc ↔ or ↓

Question 14

For 40EP-9EO05 Excess Steam Demand (ESD), the Containment Isolation SFSC is

Answer 14

• <3 psig OR CIAS actuated

- No valid CTMNT or 2° RU alarms or unexpected rise in activity

Question 15

For 40EP-9EO05 Excess Steam Demand (ESD), the Containment Temp/ Press Control SFSC is

Answer 15

Condition 1:

• < 235°F
• < 8.5 psig
• H2 < 1.1%

Condition 2:

• 1 CS Hdr flow > 4350 gpm
• < 55 psig
• H2 < 4.9%

Question 16

During For 40EP-9EO05 Excess Steam Demand (ESD), What parameters are used to determine the most affected SG

Answer 16

• SF
• Psg
• SGWL
• Tc

Question 17

During For 40EP-9EO05 Excess Steam Demand (ESD), if both SG’s are faulted should you isolate both?

Answer 17

• NO

- At least 1 SG should always be available for DHR

Question 18

During For 40EP-9EO05 Excess Steam Demand (ESD) if the wrong SG is isolated, what should you do?

Answer 18

• Restore isolated SG
• Isolate worse SG
• Do NOT isolate both SG’s

Question 19

During 40EP-9EO05 Excess Steam Demand (ESD), what must be done condenser reheat trays are high out of sight?

Answer 19

• Blowdown AFA steam trap on unaffected SG

- MUST be done within 2 HOURS

Question 20

During 40EP-9EO05 Excess Steam Demand (ESD), what parameter is used to stabilize the RCS and what is the concern associated with it?

Answer 20

• Stabilize RCS Temp with Lowest Tc

- Prevents Pressurized Thermal Shock

Question 21

During 40EP-9EO05 Excess Steam Demand (ESD) if P/T limits are exceeded during the blowdown phase and no RCP’s are running, what must be done?

Answer 21

• Maintain Temp and Pressure (soak)

- > 2 Hours

Question 22

What is HPSI Throttle Criteria?

Answer 22

• ≥ 24°F [44] RCS Subcooling
• > 10% [15] Lpzr
• Unisolated SG 45-60% NR and being fed
• RVUH ≥ 16%

Question 23

What is considered Over Subcooled in the RCS?

Answer 23

• 100°F/hr line on App 2 crossed OR
• 200°F subcooling
  AND
• Plant cooled down > 100°F/hr OR
• Uncontrolled to < 500°F

Question 24

What is the criteria for stopping both CS pumps?

Answer 24

• Running on Mini-flow

- CNTMT press not expected to exceed 8.5 psig in 1 hour

Question 25

What steps are required if CSAS has actuated?

Answer 25

• At least 1 CS hdr > 4350 gpm
• All RCP’s off
• RCP BO isolated
• Align H2 recombiners

Question 26

What is the criteria for stopping CS pumps and resetting CSAS?

Answer 26

• CTMNT press < 5 psig ↔ or ↓

- CS not required for long term cooling

Question 27

What is SDC Entry Criteria?

Answer 27

• All SFSC met
• Lpzr > 30% [38] and controlled
• ≥ 24°F [44] RCS Subcooling
• Ppzr < 385 psia
• Th < 335°F