AOP-24, STEAM GENERATOR TUBE LEAK Flashcards
What is the purpose of AOP-24, Steam Generator Tube Leak?
Provides instructions to identify and mitigate the effects of a Steam Generator Tube Leak greater than or equal to 0.003 gpm.
What are the entry conditions of AOP-24, Steam Generator Tube Luke?
Primary to Secondary leakrate greater than or equal to 0.003 gpm as calculated per one of the following:
- Chemistry Procedure CH 3.31, “Primary to Secondary Leak Rate Determination”
- PPC page 540, “Primary to Secondary Leakrate”
Adverse trends in any of the following:
- RIA-0631, Off Gas Monitor Radiation Indicator
- RIA-0707, Steam Generator Blowdown Process Monitor
- RIA-2323, Main Steam Safety and Dump Valve Discharge
- RIA-2324, Main Steam Safety and Dump Valve Discharge
- RIA-2325, Particulate Stack Monitor Remote Readout
- RIA-2326, Normal Range Noble Gas Stack Monitor
- RIA-2327, High Range Noble Gas Stack Monitor
What are the automatic actions associated with AOP-24, Steam Generator Tube Leak?
- ‘A’ Charging pump goes to max speed
- ‘B’ / ‘C’ Charging pump(s) start (if tube leakage plus letdown flow
exceeds the capacity of P-55A) - Steam Generator Blowdown Valves close (if RIA-0707, Steam Generator Blowdown Monitor setpoint is exceeded)
What are the reactor trip criteria of AOP-24, Steam Generator Tube Leak? Why do we have them?
- A sustained rise in the CVCS charging rate is needed to maintain Pressurizer level at program level
- PCS makeup requirements exceed those expected for the rate of power reduction in progress
- Radiation monitor response exceeds those expected for the rate of power reduction in progress
Steam Generator tube leak reactor trip criteria provided since a tube leak can very quickly transition into a tube rupture event.
A tube leak can become a tube burst at what leak rate?
When nominal leak rates exceeds 400 gallons per day or 0.277 gpm
What are the immediate actions of AOP-24, Steam Generator Tube Leak?
none
How do you verify primary to secondary leakage?
By observing adverse trends on at least two of the following radiation indicating monitors:
- RIA-0631, Off Gas Monitor Radiation Indicator
- RIA-0707, Steam Generator Blowdown Process Monitor
- RIA-2323, Main Steam Safety and Dump Valve Discharge
- RIA-2324, Main Steam Safety and Dump Valve Discharge
- RIA-2325, Particulate Stack Monitor Remote Readout
- RIA-2326, Normal Range Noble Gas Stack Monitor
- RIA-2327, High Range Noble Gas Stack Monitor
However, IF any of the radiation indicating monitors listed are out of service, then use PPC page 540, “Primary to Secondary Leakrate” (preferred) or Attachment 1, “Estimation of Primary to Secondary Leakrate”
What is a precaution with using PPC Page 540 to calculate primary to secondary leakage?
Acceleration rate displayed on PPC page 540 is a 15 minute average. The rate of
rise for the first 15 minutes may not be valid.
How do you confirm primary to secondary leak rates?
Either
CALCULATE PCS leakrate with minimum 15 minute duration. Refer to DWO-1, “Operator’s Daily/Weekly Items Modes 1, 2, 3, and 4.”
Or
NOTIFY Chemistry to determine primary to secondary leakrate in accordance with CH 3.31, “Primary to Secondary Leak Rate Determination.”
Why is confirmation of the leak rate, not just verification, important?
This is important since the action level leak rate criteria are orders of magnitude lower than for a ‘normal’ PCS leak.
Why is RIA-0631, Condenser Off-Gas Monitor alarm, reset?
Being in a non-alarm condition on RIA-0631 provides the opportunity to receive additional alarms if the leak rate rises.
How do you determine the affected steam generator?
DETERMINE the affected Steam Generator using any of the following:
- REVIEW Main Steam Safety and Dump Valve Discharge Monitors for adverse trends.
- RIA-2323
- RIA-2324
- VERIFY RIA-0707, Steam Generator Blowdown Monitor is not in alarm.
* NOTIFY Chemistry to sample Steam Generators for activity. - REVIEW Steam Generator(s) feed flow and steam flow indications(s) for
abnormal mismatches. - REVIEW Steam Generator(s) level indication(s) for any abnormal rise not
attributable to feed flow or swell. - NOTIFY Radiation Protection to determine dose rates on the cation
resin columns at EC-42, Turbine Analyzer Panel. - NOTIFY Radiation Protection to perform preliminary radiation surveys.
Refer to EOP Supplement 14, “SGTR Area Survey.”
What do you do if RIA-0631 is not available and the leak rate is confirmed >= 0.003 gpm?
- RETURN RIA-0631, Condenser Off Gas Monitor, to an available status as soon as practical.
Availability is based on capable of being monitored, producing an alarm in the Control Room and detecting leakrates greater than 0.02 gpm at the existing PCS activity level.
- MONITOR alternate indications for changes in the primary to secondary leakrate.
- RIA-0707, Steam Generator Blowdown Monitor
- RIA-2323/2324, Main Steam Safety and Dump Valve Discharge Monitors
- RIA-2325/2326/2327, Stack Gas Effluent Monitors (RGEM)
- NOTIFY Chemistry to determine the primary to secondary leakrate in accordance with CH 3.31, “Primary to Secondary Leak Rate Determination,” at the frequency indicated below AND TREND results.
- IF the leakrate was unstable OR was indicating a rising trend when RIA-0631 became unavailable, THEN DETERMINE primary to secondary leakage once per 4 hours AND GO TO Action Level 2.
What leak rate is associated with the “increased monitoring level?” What do you do at this level?
0.003 gpm but < 0.02 gpm with no rate of rise
- ESTIMATE the count rate indication on RIA-0631, Off Gas Monitor Radiation Indicator, which would result in a 0.02 gpm primary to secondary leakrate. Refer to Attachment 1, “Estimation of Primary to Secondary Leakrate.”
- RAISE the alarm setpoint of RIA-0631 based on the value estimated per Step 3a (not to exceed 0.02 gpm) AND RESET the monitor. Refer to SOP-38, “Gaseous Process Monitoring System.” Upper count rate limit specified in SOP-38 does not apply.
- NOTIFY Chemistry to determine the primary to secondary leakrate in accordance with CH 3.31, “Primary to Secondary Leak Rate Determination,” once per 24 hours.
- REDUCE frequency as determined by the Shift Manager when leakrate is stable.
- CORROBORATE the primary to secondary leakrate calculated from RIA-0631 count rate indication with the sample results.
What leak rate is associated with Action Level 1? What actions do you take?
- 02 gpm but < 0.05 gpm with no rate of rise
- NOTIFY Chemistry to determine the primary to secondary leakrate in accordance with CH 3.31, “Primary to Secondary Leak Rate Determination,” once per 12 hours.
* REDUCE sample frequency to once per 24 hours when leakrate is stable (less than or equal to 10% rise in 24 hours). - MONITOR RIA-0631, Off Gas Monitor Radiation Indicator every 15 minutes using PPC RIA0631 trend and/or alarm settings.
- DETERMINE primary to secondary leakrate every 15 minutes per Attachment 1, “Estimation of Primary to Secondary Leakrate,” or PPC page 540, “Primary to Secondary Leakrate.”
- REDUCE frequency to once every 2 hours when leakrate is stable for a minimum of 1 hour (less than or equal to 10% rise in 1 hour).
1. REDUCE frequency as determined by the Shift Manager when leakrate is stable for a minimum of 24 hours (less than or equal to 10% rise in 24 hours).
c. WHEN the leakrate is stable for at least 1 hour (less than or equal to 10% rise in 1 hour),
THEN:
1) ESTIMATE the count rate indication on RIA-0631 which would result in a
0.05 gpm primary to secondary leakrate. Refer to Attachment 1, “Estimation
of Primary to Secondary Leakrate.”
2) RAISE the alarm setpoint (not to exceed 0.05 gpm) of RIA-0631 AND RESET the
monitor. Refer to SOP-38, “Gaseous Process Monitoring System.” Upper count
rate limit specified in SOP-38 does not apply.
