Reactor Startup

Question 1

Why is the CEA band widened from 500 pcm to 750 pcm for initial startup following a refuel?

Answer 1

Fuel performance uncertainties

NOTE: Also denotes when Mode 2 is declared (-750-initial and -500-subsequent refuels)

Question 2

What are the sequence of events that occur during a RX startup (ZZ02/03)?

Answer 2

1. RTCB closed
2. RCS Boron at ECBC
3. Shutdown and PSCEA’s withdrawn
4. Reg Group CEA’s withdrawn as planned
5. Criticality, RX Power held constant, data point taken
6. High Log bypassed >1E-4%
7. RX Power up to POAH

Question 3

When CEA’s are below the PDIL’s, how do we determine the max magnitude of the next CEA withdrawal?

Answer 3

Select smaller of:

1. 1/2 distance to criticality in PCM, based on most recent ACP
2. The next targeted hold point

Question 4

Below PDIL’s, what allows the next CEA withdrawal to the next hold point?

Answer 4

1. Most recent ACP says RX will go Critical at a CEA position > than next hold point
2. RX is known to be far from Critical, as evidence of 3-4 CR doublings on both SU channels

Question 5

2 or more consecutive ACP’s on same power channel predict Criticality to occur BELOW the PDIL’s and we are currently < PDIL’s and ECRP position, what is done?

Answer 5

Trip RX, Ensure SDM per 3.1.2, Monitor RX Power, RX Engineering investigate

Question 6

How is “Criticality” indicated during a startup?

Answer 6

By a steadily or exponentially increasing count rate/RX Power with NO CEA Motion (Power Rise/Time)

Question 7

Who’s responsible to initially determine when Reactor is “critical”?

Answer 7

RO conducting the Startup (RX MGR then confirms)

Question 8

If the Reactor goes CRITICAL while pulling Shutdown or PS CEA’s, what should occur?

Answer 8

Simultaneously, Trip the Reactor, Initiate emergency boration until adequate SDM, Perform SPTA’s

Question 9

What are required actions if Reactor goes CRITICAL below the PDIL’s or ECRP (-500/-750 pcm)?

Answer 9

Trip the Reactor
Perform SPTA’s
Initiate emergency oration

Question 10

What are the required actions if CEA withdrawal is STOPPED due to CR doubling during withdrawal to 1st or 2nd hold points?

Answer 10

Trip Reactor, Ensure adequate SDM, Monitor RX Power (ensure no increase), Direct RX ENGR to investigate

Question 11

If CEA RG GRP 5 reaches 135” withdrawn and Reactor is still subcritical, what can be done?

Answer 11

Dilution

Question 12

What is “proper overlap” between Startup and Log Safety Channels?

Answer 12

ONE Decade

Question 13

When and why are Startup Channels turned off during a Reactor Startup?

Answer 13

1 x 10-4 CPS (When High CPS alarm received)

De-energized to protect from high flux

Question 14

What are the guidelines to raise power to the POAH?

Answer 14

Don’t exceed 1 DPM SUR
Use CEA withdrawal to get to .1% power
Insert CEA once at POAH to stabilize power

Question 15

If SBCS is in MANUAL during rise to POAH, what happens to RCS temperature?

Answer 15

Goes Off-Program HIGH

Question 16

When should Criticality be anticipated?

Answer 16

Whenever positive reactivity is being added

Question 17

When do we declare Mode 2?

Answer 17

Refuel (-750 pcm), Other time (-500)

Question 18

What are the modes of applicability for 3.3.12 (BDAS) in relation to a failure of a Startup Channel?

Answer 18

Modes 3,4,5 (loss of a channel N/A once M2)

Question 19

When is ACP evaluated?

Answer 19

After every withdrawal

By RX ENGR and STA

Question 20

What will be the withdrawals at or above the -150 pcm position?

Answer 20

75 and 100 pcm

Anticipate criticality with 0.3 DPM SUR

Question 21

What happens to RX Power when reaching POAH with SBCS in AUTO?

Answer 21

RX Power rises and stabilizes above POAH