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Alex exam 1 review > CVCS Letdown > Flashcards

CVCS Letdown Flashcards

1
Q

State the purpose of CVCS Letdown.

A

Provides a means of PZR level and pressure control.

Provides a means for cleaning up and controlling RCS chemistry.

Provides a means for adjusting boron concentration over core life and as a function of RCS temperature control.

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2
Q

How many gallons per percent level in the PZR.

A

1 % in the PZR = 66 gallons.

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3
Q

How does a decrease in LD temperature affect RCS temperature?

A

LD decreases, which causes the IX’s to pull more boron out of LD, which will dilute charging and cause a net positive amount of reactivity to be added to the Rx. This is analagous to withdrawing control rods and thus RCS temperature will increase.

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4
Q

What are the trips associated with CHA-UV-516?

A

SIAS

CIAS

Train A

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5
Q

What are the trips associated with CHB-UV-515?

A

SIAS

HI temp: >413F from RHX outlet

Train B

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6
Q

What is the setpoint of the RHX outlet relief valve? and why?

A

Set to relieve to the EDT at 600 psig to prevent saturation conditions in the RHX?

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7
Q

What is the purpose of the delay coils?

A

Allows N-16 to decay before letdown enters the Aux Bldg. Located inside containment.

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8
Q

What are the trip setpoints for CHB-UV-523?

A

CIAS

HI temp > 135F( can be overridden by going back to open-restores LD on high temperature)

Train B

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9
Q

What is the purpose of the LD pressure regulator valves, 110 P/Q?

What are their fail states and how are they operated on startup and shutdown?

A

Control LD flow from a signal from PLCS to 30 to 130GPM(150 in manual).

They fail closed on loss of power and IA.

Must operate 2 in parallel on low pressure < 1050 psia and isolated on > 1000psia on s/u.

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10
Q

Why is there a possibility of 0.5 gpm bypass flow through HV-526?

How long must bypass flow exist to warm up the LDHX?

A

Allows warmup of LDHX if isolated for > 22 min.

>4 min.

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11
Q

What is the purpose of the LDHX?

What cools the LDHX, how is temp controlled and what auto feature exists?

A

Lower LD temperature to protect the IX resin. < 120F.

It is an OPEN LOOP with NC outlet valve in auto. Has a minimum setpoint of 39GPM in auto.

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12
Q

What is the purpose of the TE-224 instrument?

What auto actions does it initiate?

A

Protects IX, Boronometer, RU 155, IX resin and LDHX.

Provides inputs to:

CHB-523 > 135F closed

CHN-520 > 135F bypass

CHN -521 > 135F bypass

CHN-201 P/Q > 148F Closed

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13
Q

What is the purpose of the LD pressure control valves, 201 P/Q?

What are the associated setpoints and auto features?

How do they fail?

A

maintain backpressure in the LDHX and associated piping to prevent flashing.

Maintains 375psig. Auto closes 148F.

Fails closed on loss of NNN-D12.

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14
Q

What is the setpoint for the PSV-354 low pressure relief valve?

A

200 psig, relieves to EDT. Protects d/s piping of the backpressure control valves.

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15
Q

What are the 3 types of IX’s?

A

Deboration(rx control late in core life)

purification(throughout core life)

Delithiation(periodically to remove lithium)

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16
Q

What does RU-155D tell the operator?

A

If >= 1 % fuel has failed.

17
Q

When does CHN-500 divert on VCT level?

when does it realign?

how does it fail?

A

> 60% will bypass to the PHIX(goes to the HUT)

will realign on < 58% and decreasing.

Fails to VCT on loss of air/ loss of power.

18
Q

What happens on a DIVERT after the water is bypassed by CHN-500?

A

CHN-565 aligns to PHIX’s, CHN-566 will divert to EDT on high level in Gas stripper.

Gas stripper is normally bypassed so that the water goes straight to the HUT.

19
Q

what are the fail states of the following valves:

CHN-565

CHN-566

CHN-567

A
  1. Fails to bypass
  2. Fails to EDT
  3. Fails to VCT
20
Q

What is the purpose of CVCS?

A

Chemistry control of RCS

Removes gases

boron rx control

aux spray

seal injection and bleedoff

ECCS borated water source

21
Q

What is the design basis of the RWT level?

A

Provides at least 20min of full flow ECCS pumps prior to reaching RAS signal level < 9.4%

22
Q

When are both LD control valves placed in service?

When is one removed on startup?

What is the consequence if both valves are left in service at NOP?

A

on shutdown, when RCS pressure is < 1050psia

on startup when RCS pressure is > 1000psia

Will lift intermediate pressure LD relief valve(@ 600psia)

23
Q

When are both LD backpressure control valves placed in service?

When is one removed from service on startup?

A

on shutdown when < 750psia.

on startup when > 1000 psia.

24
Q

What type of monitor is RU-155D and what is it designed to detect?

A

RU-155D is an area(process for test) monitor set to measure for >1% failed fuel.

25
Q

What happens on a DIVERT signal with regard to the RDT and HUT pumps?

A

STOPS RDT pumps

Stops HUT pumps( only if CHN-686- HUT to VCT makeup is open)

Prevents pumps from operating at shutoff head.

26
Q

What happens on a loss of NKN-D42 with regard to the CVCS system?

A
  • 110 P/Q LD control valves will lose indication only.
  • 201 P/Q LD backpressure ctrl valves will lose indication only.
  • CHN-LC-227 will fail to 0% and cause CHP suction to shift to BORATED source.
  • CHB-523 closes(loss of 63x relay) and LD isolated.
  • CHN-FV-210 X/Y fails closed isolating VCT Makeup
  • CHP auto control lost and pumps stop. Can start them in manual
  • RCP Seal inj FCV’s fail open.
27
Q

What is the purpose of CHE-FV-204?

What is its fail state?

A

Maintain 8pgm flow thru the Boronometer and RU0155D. Fails OPEN on loss of AIR/PWR

28
Q

What is the purpose of CHE-521?

What is its fail state?

A

Diverts to bypass B/RM on hi temp from TE-224 @ 135F.

Fails to bypass.

29
Q

What is the purpose of CHE-520?

What is its fail state?

A

Bypasses IX on hi temp from TE-224 @ 135F

Fails to bypass.

30
Q

What is the purpose of CH-500?

WHat is its fail state?

A

Diverts VCT inlet to PHIX(HUT) on hi vct lvl of 60%, resets at 58% lowering.

Fails to VCT and must be reset when pwr restored; powered from NK.

Also stops RDT pumps and HUT pumps(if 686 is open) to prevent deadheading.

31
Q

What is the minimum LD flow when LIC-110 is in AUTO?

In MANUAL?

A

30gpm

0gpm

Alex exam 1 review (5 decks)

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