Rx Start-Up Knowledge Flashcards

1
Q

State the SDM requirements for the applicable Modes of Operation

A

> /= 1.3% delta K/K w Tavg > 200*F

> /= 1.0% detail K/K w Tavg = 200*F

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2
Q

What is the minimum temperature for criticality? And Why?

TS 3.4.2 Basis

A

> /= 541*F

  1. MTC in analyzed Range
  2. Protective instrument in normal operable range
  3. PZR is capable of being in an operable status w steam bubble
  4. Vessel > RTNDT
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3
Q

When will you transition from Mode 3 –> 2?

A

Just prior to control bank C withdrawal (Admin)

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4
Q

When will you transition from Mode 2 –> 1?

A

> 5% NI’s (per TS)

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5
Q

Why do we perform an ICRR Plot?

A
  1. Backup to calculated ECP to ensure reactor is not brought critical with the control rods below the 0 power rod insertion limit.
  2. To provide the operator with another mechanism for evaluating / predicting the point at which criticality can be expected.
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6
Q

What parameters are being plotted while performing the ICRR Plot?

A

Control Bank Rod position vs. ICRR which is equal to initial counter rate over final count rate

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7
Q

What can effect the ECP?

A
  1. Changes in RCS Boron Concentration
  2. Changes in RCS T-avg
  3. Delay in Startup Xenon Effects
  4. Delay in Startup ECP validity
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8
Q

If Xenon is present, and a large delay occurs, what must be done?

A

A new calc must be made

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9
Q

What is Condition I and what must be done if you exceed the limits?

A

Critical below the Control Rod Lo-Lo Insertion Limit

  1. Emergency Borate
  2. Perform SDM
  3. Trip the Reactor and check rod bottom lights lit
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10
Q

What is condition II and what must be done if the limits are exceeded?

A

Critical at 1000 pcm below ECP / DIT provided value.

  1. Trip the reactor and check rod bottom lights lit
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11
Q

What is condition III and what must be done if the limits are exceeded?

A

Rod withdrawal to 500 pcm past ECP / Dit provided value

  1. Trip the reactor and check rod bottom lights lit
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12
Q

What does it mean when there is a doubling of counts?

A

The distance from the initial Keff to Keff = 1 is halved

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13
Q

What is the definition of SDM?

A

The amount of reactivity by which the reactor is sub critical

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14
Q

A doubling also means….

A

You added half the reactivity necessary to achieve criticality to the core.

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15
Q

How many doubling are expected before reaching criticality?

A

5-7 doubling

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16
Q

What does the High flux at shutdown alarm do?

A

Warns of reactivity increases when shutdown.

Sounds the containment Evacuation alarm.

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17
Q

What is the set point for the high flux at shutdown alarm?

A

1/2 decade above shutdown count rate.

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18
Q

What is subcritical multiplication?

A

The effect caused by the combination of a neutron source and a SUBCRITICAL reactor that produces a steady state neutron population greater than the population of source neutrons alone.

19
Q

How long is the average neutron generation time?

A

About 0.1 seconds

20
Q

As Keff gets closer to 1, the number of generations….

A

Increase significantly

21
Q

When can criticality be expected?

A

** At any time

Approx 5-7 doublings

22
Q

How can you determine if the reactor is critical?

A

Reactor is actually slightly super critical.

Indicated by a + SUR and a steadily increasing count rate with no rod movement.

23
Q

When can you block the SR high flux trip?

A

At P-6

24
Q

What is the set point for P-6?

A

1/2 IRS > 10 -10 amps

25
Q

What is the SR high flux trip?

A

90,000 Counts

26
Q

What should be verified before blocking P-6?

A

Nominal 1 decade of overlap between IR and SR

27
Q

How many switches are required for blockingg SR trips?

A

Both

28
Q

How many switched are required to unblock SR trips?

A

1

29
Q

Why do we choose 10E-8 amps to collect critical data?

A
  1. Well above SR, so source neutron effects are negligible

2. Below POAH. Doppler and Moderator Temperature effects are not present.

30
Q

What is the POAH?

A

Point where thermal output of the core exactly equals system losses.

31
Q

What are the primary and secondary indications that the POAH has been reached?

A
  1. Lowering SUR
  2. T-avg Rising
  3. PZR Pressure and Level Rising
  4. SG Pressure and Level Rising
  5. Raise in steam dump demand
32
Q

What happens to het MTC as T-avg increases?

A

MTC adds negative reactivity

33
Q

What happens to het Doppler coefficient as power increases?

A

Ads negative reactivity

34
Q

What happens to MTC as core ages?

A

It becomes more negative

35
Q

With a more negative MTC, the same change in temperature will cause a ______

A

Larger reactivity insertion so effect on POAH indication is more rapid.

36
Q

Why is the next power hold point at 4%?

A

The MDAFPs have a capacity of 450 gpm each, which is good for ~4% power

37
Q

Why is the Reactor safer at 2% power than at 10E-8 amps?

A

above the POAH, the reactor is inherently stable and closer to Rd protection set points

38
Q

What does 2% power correspond to on the IR?

A

~ 4E-6

39
Q

When is P-10 made up?

A

2/4 PR NIs are > 10% power

40
Q

What doe P-10 do?

A

Backup de-energization of SR

Allows ability to block the IR and PR low power high flux trips and the IR rod stop

Provides input into P-7, along w P-13

41
Q

When is P-10 auto unblocked?

A

3/4 PR less than 10% power

42
Q

What are the bases for rod insertion limits?

A
  1. Ensure acceptable power distribution limits are maintained
  2. SDM is maintained
  3. Limit potential effects of rod misalignment on associated accident analysis
43
Q

How does the operator ensure hot channel factors are maintained during power ops?

A

By checking (within limits):

  1. AFD
  2. QPTR
  3. RIL