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Block 6 > Containment Heat Removal > Flashcards

Containment Heat Removal Flashcards

1
Q

What is the Containment Heat Removal System Function?

A
  • Removes heat and fission products from the CNMT atmosphere after a Loss of Coolant Accident or Main Steam Line Break
  • Ensures CNMT pressure and temperature do not exceed design values of 44 psig & 264°F
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2
Q

What are the Containment Heat removal combinations which can maintain pressure and temperature below design values?

A
  • 4 CTMT Fan Coolers
  • 2 CTMT Spray Pumps
  • 1 CTMT Spray Pump & 2 CTMT Fan Coolers
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3
Q

List the ESFAS Actuations based on rising CTMT pressure.

A
  • Rx Trip occurs @ 3.3 psig [3.0 psig]
  • SIAS occurs @ 5.0 psig [3.5 psig]
    {Starts all Containment Fan Coolers (only one speed)} / [Starts all Fan Coolers (in Slow Speed)]
  • CSAS occurs @ 10 psig [5.4 psig]
    Starts Containment Spray Pumps
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4
Q

Discuss the Recirc Actuation Signal (RAS).

A

Occurs when Refueling Water Tank (RWT) Level drops below:
 Unit 1: 4 feet
 Unit 2: 5.67 feet
Opens the CTMT Sump Suction MOV’s, and Closes the RWT Suction Valves
As RWT level drops:

Unit 1:
* Power up recirc valves @ ~ 6-8 ft
* Piggy back Containment Spray pumps to provide flow from discharge of SDC HX’s to the HPSI pumps
* Watch Recirc valves swap position following RAS @ ~ 4’

Unit 2:
* Watch for RAS actuation at ~ 6’

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5
Q

What are the Containment Spray Pump Auto Starts?

A

Unit 1
CTMT pressure: 10 psig and SIAS actuated

Unit 2
CTMT pressure: 5.4 psig and SIAS actuated

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6
Q

What are the shutoff head pressures for the Containment Spray Pumps?

A

Unit 1
235 psig

Unit 2
220 psig

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7
Q

What are the Containment Spray Pump Recirc Flows?

A

Unit 1
50 gpm
{Unit 1 Mini Flow manually isolated to prevent NaOH from getting into the RWT, because Unit 1 RWT is Aluminum and NaOH would cause Caustic Embrittlement}

Unit 2
150 gpm

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8
Q

Discuss Containment Spray Pump Flow Rates.

A

Unit 1
> 4000 gpm
3425 gpm
2700 gpm

Unit 2
> 4000 gpm
3560 gpm
2700 gpm

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9
Q

Discuss Containment Spray Pump Flow Indications.

A

Unit 1
Each CTMT Spray header has (RTGB 106):
* 0-3500 gpm flow meter
* 0-600 psig pressure indicator

Unit 2
Each CTMT Spray header has (RTGB 206):
* 0-5000 gpm flow meter, and Flow recorder
* 0-600 psig pressure indicator

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10
Q

Discuss Containment Spray Suctions Valves from the RWT.

A

MV-07-1A and MV-07-1B
* Normally open
* Auto Close on RAS signal
* Close in 90 seconds.
If the RWT Suction Valves are:
a) Neither Fully OPEN Pre- RAS; or
b) SHUT within 100 sec., Post-RAS; or
c) The MOV Breaker Trips on Thermal Overload
An “RWT ISOL MV-07-1A(B) TROUBLE” Annunciator will Alarm

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11
Q

Discuss Containment Spray Suctions Valves from the Containment Sump.

A

Unit 1
MV-07-2A and MV-07-2B
* Normally closed
* Auto Open on RAS signal
* Open in 40 seconds.

Unit 2
MV-07-2A and MV-07-2B
* Normally closed
* Auto Open on RAS signal
* Open in 30 seconds.

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12
Q

Discuss the Containment Spray Header Flow Control Valves.

A

FCV-07-1A & 1B
* Air Operated
* Normally closed - Fail open
* Only valves that must open for CS
* CLOSE/AUTO/OPEN;
* Auto open on CSAS
* Fail to open alarm 10 sec after CSAS

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13
Q

Discuss the Containment Spray Header MOVs.

A

{MV-07-3A & MV-07-3B} [MV-07-3 & 4]
* Used to isolate CS during SDC to prevent inadvertent spray down of CNMT on loss of IA (FCV’s would fail open)

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14
Q

Discuss Containment Spray Header Valve arrangements.

A

Unit 1
Manual – Air - MOV

Unit 2
MOV – Air - Manual

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15
Q

Discuss the Iodine Removal System.

A
  • Removes Iodine Post Accident (LOCA) Iodine from CNMT atmosphere
  • Provide capability for fission product scrubbing of the Containment atmosphere following a LOCA such that off-site doses and doses to operators in the control room are within the guidelines of 10 CFR 100 (Reactor Site Criteria) and GDC 19 (General Design Criteria for Control Rooms), respectively.
  • Meet Iodine removal requirements based on an effective spray coverage of 85% of the Containment free volume
  • Isolated during SDC
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16
Q

Discuss the Unit 1 Iodine Removal System.

A

Basic Setup
* A nitrogen-pressurized Sodium Hydroxide (NaOH) storage tank
* Solenoid actuated isolation valves, and
* Eductors, and an orifice (for measuring flow).

pH
NaOH addition maintains both sump and CTMT spray nozzle pH of 8.5 – 11 which:
a) Increases Iodine isotope absorption
b) Minimize caustic corrosion

Tech Specs T
ech Spec Requirements:
a) MIN Volume: 4010 Gal
b) MAX Volume: 5000 Gal
c) MIN NaOH Solution: 28.5%
d) MAX NaOH Solution: 30.5%
e) 2 Operable Eductors

Storage Tank
NaOH Storage Tank
* Located in RAB -5 level
* A nitrogen blanket at approximately 3 psig helps prevent the NaOH from deteriorating.
* Lo-Lo Level (3”) in NaOH Storage Tank will close NaOH Injection Solenoid Valves

Injection Method
* Injected into CS pump suction using eductors
* CS pump discharge (off outlet of SDC Hx) goes through an Eductor which draws NaOH from the storage tank and then returns to the CS pump suction
* Injects Sodium Hydroxide (NaOH) into CS pump suction at a rate of 33-39 gpm (18 +/- 1.5 gpm per train)

Injection Valves
4 SOV’s (2 per train)
* ‘A’: SE-07-1A & 2A
* ‘B’: SE-07-1B & 2B
* Auto Open on:
 CSAS (Train related)
* Auto Close on:
 Lo-Lo NaOH Storage Tank Level (3”)
* 125 VDC, fail closed. Energize to open
* There are two injection valves in series that receive an open signal from CSAS A and two from CSAS B, however the two trains tie into a common header such that they can feed either CS pump

17
Q

Discuss the Unit 2 Iodine Removal System.

A

Basic Setup
* IRS / Hydrazine Addition System has been abandoned on U2
* Trisodium Phosphate baskets in CTMT used for pH control

pH
Sump pH is maintained 7.0 – 8.1 by Trisodium Phosphate (TSP), located in stainless steel baskets located on the 18’ and 23’ elevations in the Reactor Containment Building

18
Q

Discuss the Containment Spray Rings.

A

Purpose
* Nozzles break water flow into small drops, increase the surface area for better absorption of Heat and Iodine

Two Headers –
{178 Nozzles per header}
[4 Rings per header. 357 nozzles total]

19
Q

Discuss the Containment Cooling System.

A

System Function
* Maintains average containment temperature less than 120°F during normal operations as required by TS 3.6.5
* In combination with the CTMT Spray System, it removes heat and fission products from the CNMT atmosphere after a Loss of Coolant Accident or Main Steam Line Break

Basics
* Consists of four fan coolers HVS-1A, 1B, 1C and 1D, which are cooled by CCW
* Four units separated into two trains, each train with two fan coolers.
* All four fan coolers are connected to a ring shaped duct.
* System actuated on a SIAS to remove heat released during a LOCA

20
Q

Discuss Contaiment Cooling Fans.

A

Unit 1
* HVS-1A & 1B LC 1A2
* HVS-1C & 1D LC 1B2
* Control power from A & B DC Bus
* Single speed
* Each fan has a START/AUTO/STOP control switch on RTGB 106 that spring returns to AUTO
* Normally all 4 units running
* Auto start on SIAS or LOOP:
a) SIAS starts all 4 fans
b) LOOP starts all 4 fans
* Post LOOP – 3 second load block start
* ~60,000 cfm air flow
* CCW supplied to the Fan Cooler motors @ 50 gpm for cooling

Unit 2
* HVS-1A & 1B LC 2A9
* HVS-1C & 1D LC 2B9
* Control power from the 480V fan bkr
* Two speed fans (FAST and SLOW)
* Each fan has a START/AUTO/STOP/TEST control switch on RTGB 106 that spring returns to AUTO. It has a hard STOP position
* Fan speed can be shifted to SLOW by taking the switch to the TEST position. To go back to FAST, take switch to stop, then to START.
* FAST / REMOTE / SLOW switch on each MCC used for maintenance.
* Normally 3 units are running in FAST speed
* Auto start on SIAS or LOOP:
a) SIAS starts all 4 fans in SLOW speed
b) LOOP starts all 4 fans in FAST speed
** Will not start if switch in STOP ** Considered INOPERABLE**
* Post LOOP – 3 second load block start
* ~60,000 cfm air flow in FAST speed
~39,600 cfm in SLOW speed
* Motors NOT cooled by CCW – cooled by air flow

21
Q

Discuss Containment Cooling Coils.

A

Unit 1
* Each Fan has two banks of Cooling Coils
* Gravity dampers limit reverse flow while idle.
* Located in different quadrants in CTMT.
* CCW required to be supplied @:
a) 1350 – 1450 gpm per fan cooler.
b) (50 gpm supplied to fan motor)
* Lo flow alarm if < 1250 gpm
* CCW flow must be ≥ 1200 gpm per T/S
* One CCW isolation switch for each train of Fan Coolers, on RTGB 106

Unit 2
* Each Fan has two banks of Cooling Coils
* Gravity dampers limit reverse flow while idle.
* Located in different quadrants in CTMT.
* CCW required to be supplied @:
a) HVS-1A, B & D: 1350 – 1450 gpm
b) HVS-1C: 1380 - 1450 gpm
* Lo flow alarm if < 1250 gpm
* CCW flow must be ≥ 1200 gpm per T/S
* One CCW isolation for each Fan Cooler on HVAC Panel

22
Q

Discuss Containment Heat Removal Abnormal Operation.

A
  • Long Term CTMT heat removal post-LOCA is with Containment Spray and CTMT Fan Coolers.
  • The CCW system removes CTMT heat via SDC HXs and CTMT Fan Coolers.
  • CNTMT air temp. MUST be maintained ≤ 120°F;
  • If > 120°F, must restore within 45 min (per RCB Ventilation AOP), otherwise restore to <120°F within 45 minutes, initiate Rx Trip and cooldown to HSD within 5 hours.
23
Q

Discuss Containment Heat Removal Emergency Operation.

A

CSAS:
* 2/4 CTMT Pressure instruments reach {10 psig} [5.4 psig] and a concurrent SIAS exists.
* Initial injection lasts for a minimum of 20 minutes assuming full flow for both trains of ECCS and minimum Tech Spec RWT level
* When RWT level reaches {4’} [6’], RAS actuates and shifts the CS System to the recirculation mode.

CSAS with a LOOP
* CS System would receive power from the EDGs after 12 seconds.
* Operators should ensure that CS is actuated if CNTMT pressure exceeds {10 psig} [5.4 psig]

Manual Actuation:
* CS System can also be manually actuated from RTGB 106 [206] in the control room
* Two CSAS manual initiation switches, Train A and B, with RESET / AUTO / ON positions provide manual system control
* A “THINK” pushbutton must be depressed simultaneously while positioning the switch to INITIATE, thus avoiding accidental system actuation

24
Q

Discuss the Components Actuated on CSAS.

A

Unit 1:
1) CS Pumps Start (2)
2) CS Header Air Operated Isolation valves Open (FCV-07-1A/B)
3) All 4 NaOH Injection Solenoid Valves Open (energized).

Unit 2:
1) CS Pumps Start (2)
2) CS Header Air Operated Isolation valves Open (FCV-07-1A/B)

25
Q

Discuss CTMT Spray Termination criteria (From 1(2)-EOP-03).

A

Early CTMT Spray Flow Reduction Criteria
Unit 1
N/A

Unit 2
* Both CS Pumps are running and:
 CTMT pressure < 42 psig and lowering
 ≥ 2 CFC’s running
 SIAS is actuated
 SI flow w/in Fig 2 limits

CTMT Spray Termination Criteria
Unit 1
* CTMT pressure < 5 psig and stable or lowering
* CS is not required for CTMT cooling
* CS is not required for Iodine removal
* CS is not required for HPSI subcooling

Unit 2
* CTMT pressure < 3.5 psig and stable or lowering
* CS is not required for CTMT cooling
* CS is not required for Iodine removal

26
Q

Discuss Containment Heat Removal Precautions and Limitations.

A
  • Spray System and SDC HXs, operation of certain valves could negatively impact the operability of Containment Spray and NaOH [N2H4] Systems shall be isolated prior to initiating SDC operations.
  • Due to the interface between the Containment either system.
  • Containment Fan coolers have limits on consecutive starts [speed changes].
  • Momentary overload, low flow and/or high vibration alarms are considered normal when starting or stopping Containment Fan Coolers.
  • After placing a Fan Cooler switch in STOP, return the switch to AUTO, or declare that Fan Cooler inoperable.

Block 6 (7 decks)

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