Systems Exam 3 - Containment Spray

Question 1

CSP Auto Starts

Answer 1

→SI Signal in conjunction with SIS on step 4 (No start on BOS)
→CS initiation signal (Hi-3 Cntmt Pressure 18.2 psig or Manual)

Question 2

LV-4754/4755 (Chem Add Tank MOVs) auto open / close on:

Answer 2

→CS initiation signal
→Close on a low level in the Chem Add Tank (~13%)
→follows normal power supply/train convention

Question 3

-LV-4752/4753 (Chem Add Tank AOVs) auto close on:

Answer 3

→normally open
→fail open on loss of air or power
→Lo-Lo level in the Chem Add Tank (~6%).
→Power supply from opposite train

Question 4

FV-4772-1, 4772-2 & FV-4773-1, 4773-2 (Recirc Valves) Interlocks

Answer 4

→auto close when Train related HV-4782/4783 (Sump Suction) begin to open
→auto close when Train related HV-4776/4777 (CIVs to Header) begin to open
→auto open on low discharge flow (< 1090 gpm) if the above valves are closed
→auto close on hi discharge flow (> 1210 gpm)

Question 5

HV-4776/4777 (Containment Spray HX Outlet Valves/CIVs) auto open on:

Answer 5

→CS initiation signal (2/4 Hi-3 Cntmt or Manual)
→valves are designed to slowly open (takes ~ 110 secs) to prevent pump runout while spray header fills.

Question 6

HV-4574/4575 CS HX CCW Out Valves auto open on:

Answer 6

→CS initiation signal (2/4 Hi-3 Cntmt or Manual)
→valves fully open, then throttle back to 55% of HX design flow
→if valves are already throttled to >55% design flow, they will only throttle down to 55%; will not go full open first

Question 7

TS 3.6.7 Chem Add Tank requirements

Answer 7

→NaOH concentration must be between 28% - 30% by weight
→Level must be maintained 91% - 94%.
→1-4 psig N2 overpressure

Question 8

TS 3.6.6 CS System MODE requirements

Answer 8

2 trains required in modes 1 - 4

Question 9

TS 3.5.4 RWST

Answer 9

→Boron 2400-2600 ppm (restore in 8 hrs)
→Level > 95% or 473,731 gallons (restore in 1 hr)
→Temp 40 -120˚F (restore in 8 hrs; if too cold, heat by recirc through CSPs)

Question 10

Containment Spray is initiated by:

Answer 10

→Manual (2 of 2 H/S)
→HI-3: 18.2 psig (2 of 4)

Question 11

Swapover to Containment sump recirc is done when?

Answer 11

→Swapover to ctmt sump recirc is done when RWST is < 6%.
→System must be manually swapped. (EOS-1.3)
→cooling is required in recirc mode

Question 12

Recirc Valves FV-4772-1/2 & FV-4773-1/2 Auto Open / Auto Close

Answer 12

→auto open at 1090 gpm (decreasing flow)
→auto close at 1210 gpm (increasing flow)
→auto close when containment sump suction valves (isolate RWST from sump) or HX outlet valves (prevent runout) begin to open; interlock overrides flow interlocks

Question 13

Containment Design Pressure and Temperature, and purpose of CT

Answer 13

→Design Pressure: 50 psig
→Design Temperature: 280°F
→Maintain containment within these limits while also removing Iodine.

Question 14

Containment Spray is designed to mitigate what accidents?

Answer 14

→MSL Break inside containment
→FW Line Break inside containment
→LOCA

Question 15

What chemical is used in the Containment Spray Chem Add tank and why?

Answer 15

→sodium hydroxide (NaOH) is used to raise pH in the containment sumps to a level more conducive to absorption and retention of radioactive iodine
→raising pH in the sump reduces corrosion of components in Containment, which minimizes hydrogen production
→pH raised from 4.6 to 7.1

Question 16

Per OPGD-3, what exception is made for Containment Spray?

Answer 16

Operators are expected to preemptively actuate ESF signals if plant conditions indicate they will auto-actuate, with the exception of Containment Spray.

Question 17

What color is the CSP 86M Phase Overcurrent light?

Answer 17

white

Question 18

If 1 Containment Spray Pump is inoperable, then the other pump in that train must be…

Answer 18

…taken to pullout due to runout concerns.

Question 19

Why are the spray risers in containment kept filled with demin water?

Answer 19

to reduce time until spray begins

Question 20

RWST Info

Answer 20

→~500,000 gallons each, one per unit
→Hi alarm >97.89%
→TS required level >95%
→Lo alarm <92.83%
→Lo-Lo alarm <33%
→Empty alarm <9%
→Low temp alarm 45° F

Question 21

Containment Spray system response to SI

Answer 21

→SI causes CSP start and run in recirc
→recirc happens before HX
→eductor flow path is open, but chem add tank MOV isolations stay closed

Question 22

Containment Spray Pump Info

Answer 22

→separate bearing coolers (SSW cooled) and seal coolers (safeguards CCW cooled)
→when one train related pump is OOS, take other pump to pullout
→if one pump in a train trips during spray, ensure other pump parameters are good and allow remaining pump to continue running
→system designed to operate with system temp up to 300° F; when system temp >150° F, CCW flow must be aligned to pump seal coolers to maintain integrity of mechanical seals
→auto-start on SIS step 4, Hi-3 containment pressure 18.2 psig; no start on BOS
→trip on sustained bus undervoltage, 86M phase overcurrent lockout (white light on handswitch)