Safety Injection (SI)

Question 1

What is the ECCS Design Criteria?

Answer 1

CLOTH

• Core geometry changes remains coolable (Coolable Geometry)
• Long term cooling to maintain core temperature
• Oxidation of cladding not exceed 17% times the total cladding thickness
• Temperature of the cladding less than 2200 °F
  ○ To prevent zira-alloy reaction which will produce hydrogen
  -Hydrogen generated less than 1% times amount generated if all cladding around fuel reacted

Question 2

What are the functional design requirements of the RWT?

Answer 2

-20 minutes of full safety injection flow (all pumps/both trains) with 10% margin above RAS
-fill refuel pool and/or cavity
-equal flows are delivered to each injection point, regardless of break location

Question 3

What is the purpose of the HPSI pumps?

Answer 3

a single HPSI pump can supply adequate water to the core to match decay heat boil-off rates soon enough to minimize core uncovery

Question 4

What is the flow and discharge pressure of the HPSI pumps?

Mini-flow rate and maximum time?

Minimum required flow for long term?

Answer 4

815 gpm plus 85 gpm recirc flow at 1234 psia

Pump shutoff head 1776-1962 psia
○ One hour at 85 gpm miniflow

Minimum required long term flow rate 225 gpm (at the pump), 250 on CR indicators

Question 5

When is long term HPSI injection initiated?

Answer 5

2-3 hours post LOCA

Question 6

What are the flow and pressure parameters for the LPSI pumps?

Answer 6

○ 210 psia shutoff head
○ One hour at 100 gpm miniflow
○ Unlimited operation >/= 2400 gpm

Question 7

What are the flow and pressure parameters for the CS pumps?

Answer 7

○ 3890 gpm plus 125 gpm mini flow at 220 psia
○ 290 psia shutoff head
○ One hour at 150 gpm mini flow
○ Unlimited operation > 2100 gpm

Question 8

What are the limitations for putting a CS spray pump on SDC?

Answer 8

<200*F / <250 psia

prevents pump damage

Question 9

How much SI flow is required for post-accident conditions?

Answer 9

4350 gpm

Question 10

If LPSI is lined up for Containment spray flow, will you be able to see flow?

Answer 10

no

the flow indicator is upstream of where the LPDI pumps ties into the spray header

Question 11

Can you override a CS pump on an inadvertent CSAS (no SIAS)?

If the breaker is anti-pumped and a SIAS occurs, how can the pump be restarted?

What if a LOP occurs before you reset the CSAS?

Answer 11

take handswitch to stop (anti pumps breaker)
clear the CSAS and cycle control power

HS to Start twice

pump will auto start again and MOV will open again

Question 12

Where are the SI pump Combined Recirculation Valves, UV-671/672, powered from?

How do they fail?

when would they automatically close?

Answer 12

PKA/B

fail closed

close on a RAS

Question 13

What is the purpose of SDC system?

Answer 13

reduce temperature of the RCS during post shutdown periods from approximately 350F to refueling temperature of 125F