C5101 - SRMs

Question 1

What are the Retract permissives for SRMs?

Answer 1

> 106 CPS
Both associated IRM’s range 3 or above
Mode switch in RUN
SRM bypassed

Question 2

Can SRMs be retracted any time?

Answer 2

Yes, but may cause SCRAM or rod block

Question 3

What causes INOP for SRM?

Answer 3

SOO/MU/HVL

Switch out of operate
Module unplugged
High voltage low <300 vdc

Question 4

When is INOP bypassed for SRMs?

Answer 4

IRM range 8

Question 5

What causes a SRM scram?

Answer 5

> 2x10^5 cps
INOP
single point causes a full scram

Question 6

How are scrams bypassed?

Answer 6

Shorting links installed (normally installed)

Question 7

When are SRMs bypassed?

Answer 7

Range 8 on IRM

Mode switch in Run

Question 8

What’s the purpose of the pulse height discriminator?

Answer 8

Filters out electrical pulses that are not caused by neutron interactions in the SRM detector

Question 9

When does SRM overlap with IRM?

Answer 9

2 of 40 IRM range 1
<1x10^5 cps (no rod block)
SRM fully inserted

Question 10

What range can SRMs read?

Answer 10

1x10^-7 up to 30% CTP

10^-1 to 10^6 cps

Question 11

What causes rod block for SRM? and when are they bypassed?

Answer 11

1x10^5 cps (bypassed in RUN or IRM range 8)

INOP (bypassed in RUN or IRM range 8)

Question 12

What are SRMs made of?

Answer 12

Fission product chamber pressurized to 220 psig of Argon gas with 350 vdc applied between detector case and center electrode

Question 13

What’s the power supply to the SRM drive motor?

Answer 13

480v 14B11

Question 14

What’s the power supply to the control circuit?

Answer 14

14P11

Question 15

When will the short reactor period come in?

Answer 15

< 50 second period

Question 16

What will increasing voltage do to SRM?

Answer 16

Increases sensitivity

Question 17

what will too much voltage cause?

Answer 17

causes “breakdown voltage” making the SRM useless

Question 18

Where are the SRMs located when full in or full out?

Answer 18

15” above centerline of active fuel (Full in)

30” below bottom of active fuel (Full out)

Question 19

What is the purpose of SRMs?

Answer 19

Source Range Monitoring

Low power monitoring. used to monitor Neutron flux (Rx power) in start-up, refuel, and shutdown.
Can produce Rod blocks

Question 20

How many SRMs are there?

Answer 20

There are 6 SRMs: A-F

Question 21

How many SRMs are required in different modes?

Answer 21

Mode 2 4 required
Modes 3,4 2 required
Mode 5 Only one SRM channel required to be operable during spiral offload or reload when the fueled region includes only that SRM detector, special movable detectors may be used in place of SRMs if connected to normal SRM circuits