ONI Entry Conditions & IAs

Question 1

ONI-B21

Inadvertent initiation of SRV

Answer 1

Entry Conditions
SRV alarms on 680 & 608
Rumbling noise in containment
SP Temp Increase
SP level increase
Main Gen MW decrease
Steam flow/Feed flow mismatch
Red solenoid indicating light
ADS SRV pressure monitoring red indicating light
SRV pressure monitoring red indicating light

Immediate Actions
Prior to any of the following:
 SP Avg temp reaches 110F
 RPV pressure reaches 1065#
  Scram

If 3 or more SRVs open in Mode 1 or 2:
  Scram

Evacuate containment

Reduce Prx with flow to ≤ 96%

When Prx ≤ 96%:
 Verify Rx pressure < 1033#

Question 2

ONI-C11-1

Inability to move control rods

Answer 2

Entry Conditions

CRD pump malfunction:
 CRD Drive DP < 250#
 No CRD pump Amps
 CRD charging pressure < 1800#

FCV Malfunction:
 CRD Cooling water DP < 15 psid
 CRD Cooling water flow < 54 gpm
 CRD total system flow < 40 gpm

RCIS Malfunction:
 Data fault backlit
 Insert/Withdraw block or inhibit light lit
 Channel disagree

No change in power when attempting to move rod.

Control rod takes ≥ 30 seconds to settle & is not identified as a slow to settle rod.

Question 3

ONI-C34

Feed Flow Malfunction

Answer 3

Entry Conditions
Unexpected changes in:
Rx Level
FW flow
Steam flow
RFPT flow
MFP flow
RFPT RPM
MFP Amps

Feed flow to steam flow mismatch
Loss of HMI

Immediate Actions
If flow control malfunction occured:
 Xfer effected RFPT(s) to manual dial
 If its the MFP, place MAN/AUTO station in manual

If a feed pump is lost, start an available feed pump.

Question 4

ONI-C51

Unplanned change in reactivity

Answer 4

Entry Conditions
Anything that changes power that happens inadvertently:
Feed Flow malfunction
Recirc pump trip or inadvertent downshifts
FCV malfunction
Loss of a heater

When OPRMs are inoperable, entry into the MANUAL SCRAM region or entry into the CONTROLLED ENTRY/IMMEDIATE EXIT region not in accordance with approved instruction.

When OPRMs are operable, entry into the IMMEDIATE EXIT region.

FMEOD > 1.00

Immediate Actions
Scram the Reactor on any of the following conditions:
More than one control rod inadvertently scrammed.
Unexplained power rise which cannot be quickly terminated.
When OPRMs inoperable, entry into the Manual scram region.
This is > 75% rod line with core flow < 42 mlbm/hr
No recirc pumps running in Mode 1 or 2
Power oscillations observed
Any APRM oscillates more than 10%
Periodic LPRM Upscale & downscale alarms
SRM Period oscillating between +/- 100 seconds

If flow cannot be controlled, arm & depress the HPU SD Switches.

If OPRMs are operable and entry into the immediate exit region, insert cram rods to 35% Prx.

Question 5

ONI-C71-1

Scram

Answer 5

Entry Conditions
You’ll know

Immediate Actions
Verify the following:
Mode switch locked in S/D
RPS initiated, if not manually initiate.
ARI initiated if RPS failed to scram the reactor.

If Prx > 4% or unknown:
Perform crew update: “Commencing ATWS Actions.”
Perform P680 & P601 ATWS Hard cards

Stabilize level using Feed/RCIC/HPCS as necessary.
If two RFPTs were operating, once vessel level is rising, perform the following:
Verify RFPT A tripped
Xfer to 1E
Verify MFP in operation & injecting
If MFP is available, trip B RFPT.

Stabilize pressure with turbine/turbine bypass valves/SRVs

Perform the update