LOT 201.22 ESF

Question 1

• LOT 201.22 ESF*
• • *

What are the four phases of a DBA LOCA?

Answer 1

• *Blowdown**
• Begins with LOCA and ends with RCS pressure = CTMT pressure*
• *Refill**
• Water at bottom of the reactor vessel and reaches the bottom of the fuel rods via addition of ECCS (Accumulators and SI pumps).*
• *Reflood**
• Rx vessel filled with water*
• Core temperature rise has terminated*
• Core temperatures have been reduced to their long term steady state level.*
• *Long Term Recirculation**
• Cold Leg Recirc (1^st Phase)*
• Hot Leg Recirc (2nd Phase)*
• Hot Leg Recirc starts 5.5 hrs after start of LOCA and cools upper head and prevents boron precipitation.*

Question 2

• LOT 201.22 ESF*
• • *

What will cause an SI auto recirculation signal?

Answer 2

SI Signal

AND

RWST Level - Low 2 (≤ 75,000 gal)

Closes HHSI AND LHSI pump mini-flow valves.

When ≥ 1 valve for each pump closed:

• Opens containment sump → SI suction header Isolation valve.

RWST → SI suction header isolation valve must be manually closed by operator. (CP001)

• Note:*
• Reset is located on CP001*

Question 3

• LOT 201.22 ESF*
• • *

What are the ESF support systems?

Answer 3

ECW cooling pond

ECW

CCW

ESF DG’s

Question 4

• LOT 201.22 ESF*
• • *

What conditions must be met in order to reset the ESF DG sequencer on CP003?

Answer 4

Loading Sequence Complete

SI Reset

UV Cleared

Question 5

• LOT 201.22 ESF*
• • *

What is the ultimate heat sink for STP?

Answer 5

ECW Cooling Pond

Question 6

• LOT 201.22 ESF*
• • *

What are the Emergency Core Cooling System (ECCS) acceptance criteria?

Answer 6

• *Peak Cladding Temperature**
• ≤ 2200 ˚F*

Cladding Oxidation
≤ 17% the total cladding thickness before oxidation.

• *H₂ Generation**
• ≤ 1% the total amount of H₂ produced from all metal surrounding the fuel reacting*
• (excludes metal around plenum volume)*

Coolable Geometry

Long-Term cooling

DBAs:

• LOCA
• SLB
• Fuel Handling Accident

Question 7

• LOT 201.22 ESF*
• • *

What are the 10CFR50.67 site criteria used for ESF evalutations? (TEDE after accident)

Answer 7

• Individual on boundary of exclusion zone:*
• *Following fpp release, during any 2 hr period will receive ≤ 25 rem TEDE**
• Individual on boundary of low population zone:*
• *Exposed to radiation cloud (entire passage) will receive ≤ 25 rem TEDE**
• Control Room Personnel:*
• *≤ 5 rem TEDE**

Question 8

• LOT 201.22 ESF*
• • *

What accident(s) is ESF designed to protect against?

Answer 8

• *LOCA**
• Double guillotine shear of cold leg*
• *Rod Ejection**
• Most reactive control rod*
• *MSL Break**
• Double ended shear of largest piping*

Fuel Handling Accident

Question 9

• LOT 201.22 ESF*
• • *

What systems make up the ESF system?

Answer 9

• RCS M/U:*
• *ECCS**
• HHSI, LHSI, SI, Accumulators*
• S/G M/U:*
• *Aux FW**
• Containment:*
• *Containment Isolation**
• *Containment Heat Removal**
• *Containment Combustible Gas Control**
• HVAC:*
• *EAB / CRE HVAC**
• *FHB HVAC**