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CVCS Flashcards

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1
Q

What is the purpose of the CVCS?

A
  • Maintain required volume of water in the PCS over the range of full to zero reactor power without requiring makeup.
  • Maintain the chemistry and purity of the PCS.
  • Maintain the desired boric acid concentration of the PCS.
  • Pressure test the PCS
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2
Q

What is the operation of CV-2001, Regen HX Letdown Stop Valve?

A
  • Normally in AUTO, which opens the valve to allow letdown flow into the Regen HX.
  • Auto closes at 470 F on the outlet of the Regen HX.
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3
Q

What is the purpose/function of the Regen HX?

A

Provides initial cooling of letdown and preheating of charging. Designed to maintain letdown < 450 F with max letdown flow and min charging.

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4
Q

What is the operation of CV-2003, 2004, and 2005, Letdown Orifice Stop Valves?

A

Controlled by PZR Level Controller when in AUTO. Normally 1 stop valve in OPEN, and the other 2 are in AUTO.

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5
Q

When are CV-2002 and 2202, Letdown Orifice Bypass Valves, used?

A

Used during low PCS pressure operations to raise letdown flow when there isn’t enough PCS pressure to force flow through the letdown orifices.

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6
Q

What automatic function is associated with CV-2002 and 2202, Letdown Orifice Bypass Valves?

A

When in AUTO, CV-2002 will close at:

  • 500 psig at the inlet of the Letdown HX
  • 190 psig downstream of the Intermediate Pressure Letdown Control Valves
  • 160 gpm downstream of the Intermediate Pressure Letdown Control Valves
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7
Q

How much flow does each Letdown Orifice pass?

A

40 gpm each

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8
Q

What is the purpose/function of RV-2006, Letdown Relief Valve?

A

Relieves at 600 psig to the Quench Tank to provide overpressure protection for the letdown line and components.

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9
Q

What is the purpose/function of the Letdown HX?

A

Cooled by CCW. TCV controls CCW outlet flow to cool letdown to within design limits of the demineralizers.

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10
Q

What is the normal Letdown HX outlet temperature?

A

110 F

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11
Q

What is the high temperature alarm setpoint for the Letdown HX outlet?

A

130 F

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12
Q

What is the automatic function associated with CV-2009, Containment Letdown Isolation Valve?

A

Isolates on CHP/CHR, which will most likely cause RV-2006 to lift.

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13
Q

What is the purpose/function of CV-2012 and 2122, Intermediate Pressure Letdown Control Valves?

A
  • Maintains pressure between the Letdown Orifices and the Letdown HX above saturation pressure to prevent flashing of letdown fluid prior to being cooled by the Letdown HX.
  • Reduces letdown pressure to within design limits of the demineralizers.
  • Controls PCS pressure during solid plant operations.
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14
Q

How are CV-2012 and 2122, Intermediate Pressure Letdown Control Valves interlocked with the Letdown Orifice Stop Valves?

A

Opening or closing a Letdown Orifice Stop Valve causes a step change in the Intermediate Pressure Letdown Pressure Controller output signal.

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15
Q

What is the automatic function associated with CV-2014, VCT Rad Monitor Stop Valve?

A

When in AUTO, valve will close at 130 F downstream of the Letdown HX. Rad Monitor is retired in place, so this valve is normally in the CLOSE position.

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16
Q

What is the purpose/function of CV-2023, Ion Exchanger Bypass Valve?

A

3 way valve that either directs letdown flow through the demineralizers, or bypasses flow around them to the VCT. When in AUTO, valve is aligned to allow flow through the deminerlizers, and bypasses them at 130 F at the outlet of the Letdown HX.

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17
Q

What are cation resins used for in the CVCS demineralizers?

A

To remove lithium for pH control

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18
Q

What are mixed bed resins used for in the CVCS demineralizers?

A

Purifies the PCS by removing corrosion and fission products.

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19
Q

What type of resins are in our 3 CVCS demineralizers?

A
  • 1 demin has cation resin and is used as the delithiating demin.
  • 2 demins have mixed bed resin. 1 is boron saturated, and is in service at all times for purification. The other demin is not boron saturated, and is placed in service for short periods of time at the end of core life as a better means of removing boron from the PCS instead of diluting.
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20
Q

What is the purpose/function of F-54A/B, Purification Filters?

A

2 filters in parallel, downstream of the CVCS demineralizers to remove resin fines and non-solubles.

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21
Q

At what D/P do F-54A/B, Purification Filters, alarm?

A

35 psid

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22
Q

What is the purpose/function of CV-2056, Letdown to VCT or CWRT?

A

3 way valve to allow letdown flow to the VCT, or divert it to the CWRTs via the VDT. Normally lined up to the VCT.

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23
Q

What VCT level causes CV-2056, Letdown to VCT or CWRT, to reposition?

A

Swaps to divert flow to the Vacuum Degasifier Tank at 94.4%, and swaps back to the VCT at 91.4%.

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24
Q

What is the purpose/function of T-54, Volume Control Tank (VCT)?

A
  • Normal suction source for the charging pumps

- Sized to allow a full power to zero power swing without diverting, or a zero power to full power swing without makeup

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25
What gas is supplied to the VCT?
- Hydrogen when online | - Nitrogen when shutdown
26
What are the normal level and pressure in the VCT?
68-78% | 21-35 psig
27
What is the purpose/function of CV-2080, VCT Vent Valve?
Manually operated, normally closed control valve. Opened to vent the VCT to the WGST.
28
What is the purpose/function of CV-2087, VCT Outlet Isolation?
- Normally open to supply suction to the Charging Pumps from the VCT. - Auto closes on SIS, or VCT Lo-Lo level of 7.9%.
29
What is the purpose/function of MO-2140, Boric Acid Pumped Feed Isolation?
Normally closed valve that opens on SIS to provide a flow path from the BASTs, through the Boric Acid Pumps, to the suction of the Charging Pumps for emergency boration.
30
What is the purpose/function of CV-2155, Boric Acid Blender Outlet Control Valve?
- Provides a flow path from the outlet of the blender to the suction of the Charging Pumps. - Closes on SIS
31
What is the purpose/function of MO-2169 and MO-2170, Boric Acid Gravity Feed Isolations?
- Normally closed. - Open on SIS to provide a gravity fed flow path from the BASTs to the suction of the Charging Pumps for emergency boration.
32
What is the purpose/function of MO-2160, SIRWT to Charging Pumps Isolation Valve?
- Supplies SIRWT to suction of the Charging Pumps - Should only be used for PCS cooldown, or while in cold shutdown to makeup for system losses. - Normally closed - Opens on VCT Lo-Lo level of 7.9% - When open, gravity feed from the BASTs is not available due to higher head in the SIRWT
33
What is the purpose/function of T-53A/B, Boric Acid Storage Tanks?
Either tank contains enough boric acid to get to Mode 5.
34
What level is normally maintained in T-53A/B, Boric Acid Storage Tanks?
95-100%
35
What are the alarms associated with T-53A/B, Boric Acid Storage Tanks?
- Each tank has high level alarm at 100% - Common low level alarm at 94.5% - Each tank has a low level alarm at 20% - Each tank has a Lo-Lo level alarm at 2.1% - Each tank has a high temperature alarm at 170 F - Each tank has a low temperature alarm at 150 F
36
What is the purpose/function of P-56A/B, Boric Acid Transfer Pumps?
Normally off. Pumps are started and tank recir valves are opened to provide a flow path for chemistry sampling. Pumps start on SIS to pump the contents of the BASTs to the suction of the Charging Pumps.
37
What is the purpose/function of the Boric Acid Blender?
Designed to mix boric acid and makeup water for makeup to the VCT or SIRWT.
38
What is the purpose/function of T-77, Boric Acid Batch Tank?
569 gallon tank used for preparation of concentrated boric acid solution. Approximately 11 batches required to fill an empty BAST.
39
What is the purpose/function of CV-2165, Primary Makeup Water Control Valve?
Used to supply 0-120 gpm of PMU to the blender for dilutions and blends.
40
What are the flow capacities of the Charging Pumps?
P-55A - 33-53 gpm | P-55B/C - 40 gpm
41
What is the purpose/function of CV-2111, Charging Line Stop Valve?
No auto function. Used to isolate charging to containment.
42
What is the purpose/function of CV-2113/2115, Charging Line Loop 1A/2A Stop Valves?
No auto function. Used to isolate charging to associated individual loop.
43
What is the purpose/function of CK-CVC2112, Charging Line Loop 1A Relief Check Valve?
If charging is isolated, and letdown flow continues, heat is added to the charging line through the Regen HX. This causes thermal expansion in the charging line. CK-CVC2112, Charging Line Loop 1A Relief Check Valve, provides a relief flow path around the Loop 1A charging line isolation valve.
44
What is the purpose/function of CV-2117, Charging Line PZR Aux Spray Isolation Valve?
Normally closed. Opens to provide spray to the PZR when no PCPs are running. Also can be used as an alternate flow path for hot leg injection.
45
What is the purpose/function of CV-2083 and CV-2099, PCP CBO Valves?
Normally open to provide a CBO flow path back to the VCT. Close on CHP/CHR.
46
What is the purpose/function of CV-2191, PCP CBO Stop Valve?
Normally open to provide a relief flow path to the VCT through a relief valve. Valve fails closed, but has an accumulator to hold the valve open. If CBO is isolated from the VCT on CHP/CHR, flow through this valve will allow the relief valve to maintain CBO pressure at 145 psig.
47
What auto actuations occur on a VCT Lo-Lo level of 7.9%?
VCT Outlet and Blender Outlet close, and SIRWT Outlet to Charging Pumps opens to swap Charging Pump suction from VCT to SIRWT to protect the pumps. Valves can be manually re-positioned when level recovers to 10.8%.
48
What CVCS auto actuations occur on SIS?
- All 3 Charging Pumps start - Both Boric Acid Pumps start - BAST Recirc Valves close - Boric Acid Pumped Feed and Gravity Feed MOVs open - VCT Outlet closes
49
What CVCS auto actuations occur differently on SIS without offsite power compared to SIS with offsite power available?
Without offsite power, P-55A/C start after 2 seconds, and P-55B doesn't start unless a low flow condition of 25 gpm exists.
50
How does the CVCS control PCS pressure during solid plant operation?
Intermediate Pressure Letdown Controller varies letdown flow for a fixed charging rate, thus controlling PCS pressure by controlling PCS volume.
51
Why is hydrogen used as a cover gas in the VCT?
Hydrogen scavenges oxygen, which causes corrosion.
52
What is the reason and method of PCS degas prior to opening the system?
- Removes hydrogen prior to opening the PCS. - Accomplished by isolating hydrogen to the VCT, and venting the PZR vapor space to the VDT. VCT is vented, as necessary to maintain ~10 psig, while filling the VCT to ~94%. This lowers hydrogen at a rate of approximately 1 cc/kg per hour.
53
What are the consequences of improperly transferring Intermediate Pressure Letdown Control Valves in manual?
Controller has to be calibrated based on which valve is being controlled. If swapped online, it will cause a letdown pressure variation, and will possibly lift the letdown relief valve.
54
What are the power supplies for the Boric Acid Pumps?
P-56A - MCC-2 | P-56B - MCC-1
55
What are the power supplies for the Charging Pumps?
P-55A - LCC-12 P-55B - LCC-12, LCC-11 (backup), and LCC-13 (backup) P-55C - LCC-11, LCC-13 (backup)
56
What is the power supply for MO-2087, VCT Outlet Isolation Valve?
MCC-1
57
What is the power supply for MO-2140, Boric Acid Pumped Feed Isolation Valve?
MCC-2
58
What is the power supply for MO-2169 and MO-2170, Boric Acid Gravity Feed Isolation Valves?
MCC-1
59
What is the power supply for MO-2160, SIRWT to Charging Pumps?
MCC-2
60
What are the consequences of operating P-55B or P-55C from alternate power supply, LCC-13?
- Pump must be started and stopped locally at the breaker, so the PZR level controller has no effect on the pump. - The only pump protection that is provided is breaker protection (no pump trips).
61
What is the alternate charging flow path into the PCS?
If the normal charging flow path malfunctions, alternate flow path is provided by injection nozzles on the redundant HPSI lines.
62
What are the documentation requirements when using the alternate charging flow path?
Each cycle on each injection nozzle shall be logged, including duration and charging temperature to ensure an even distribution of thermal stresses.
63
Why is PCS pressure maintained as low as subcooling limits allow during degas operations?
Lower pressure causes more gas to come out of solution, so it enhances degas through the PZR.
64
What is the consequence of manually tripping P-55B/C, Charging Pumps, when they are in AUTO?
Anti-pump feature will prevent the pump(s) from auto starting.
65
What is the consequence of rapidly changing letdown flow rates?
Causes rapid CCW temperature changes, which could effect the PCP seals.
66
What are the actions required to initiate emergency manual boration via pumped feed?
- D Bus energized - Charging flow > 33 gpm - Start a Boric Acid Pump - Open pumped feed isolation valve - Verify charging flow still > 33 gpm
67
What are the actions required to initiate emergency manual boration via gravity feed?
- C Bus energized - Charging flow > 33 gpm - Open gravity feed isolation valves - Close Blender Outlet and VCT Outlet - Ensure SIRWT to Charging Pumps Isolation closed - Verify charging flow still > 33 gpm
68
What control room parameters should be monitored to verify that boration/dilution response is as desired?
- Compare batch readings, flow rate vs time, and tank levels. - Monitor RX power, Tave, and startup rate - Ensure CVs close at the end of the batch by ensuring flow stops on the controller
69
What is the consequence of losing cooling water to the Letdown HX?
Outlet temperature will rise, and demineralizers will be auto bypassed.
70
What is the minimum flow limit for the PMU controller, and why does it exist?
Flow rates between 5 and 30 gpm may produce flow errors of up to 2 gpm.
71
What is the reason for the maximum flow limit for the boric acid controller?
Limited to 25 gpm to prevent over ranging the flow indication.
72
What is the effect on heat balance power of manually changing letdown flow?
Heat balance power rises as letdown flow rises.
73
What are the consequences of failing to monitor PZR and VCT level following isolation of letdown and charging at rated conditions?
PCP controlled bleedoff flow will cause VCT level to rise and PZR level to lower.
74
What are the consequences of not having the low pressure letdown temperature controller in auto when restoring charging/letdown?
Letdown HX CCW Outlet Valve wouldn't respond to maintain letdown temperature.
75
What are the consequences of not having the Letdown HX CCW D/P Controller in auto when restoring charging/letdown?
Could damage the Letdown HX due to high flow conditions.
76
What are the consequences of not having P-55B/C in auto when restoring charging/letdown?
Pumps won't auto start, causing PZR level control issues.
77
What are the consequences of not having the Letdown Orifice Isolation Valves (CV-2003, 2004, 2005) in auto when restoring charging/letdown?
Valves won't open/close automatically, causing PZR level control issues.
78
What are the consequences of not having the Letdown Stop Valve in auto when restoring charging/letdown?
Auto closure on high temperature defeated, so there would be a potential for equipment damage due to high temperature.
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