ML20053A298
| ML20053A298 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 05/11/1982 |
| From: | OMAHA PUBLIC POWER DISTRICT |
| To: | |
| Shared Package | |
| ML20053A183 | List: |
| References | |
| EP-30-1, NUDOCS 8205250183 | |
| Download: ML20053A298 (8) | |
Text
.
EP-30-1 Q"
Fort Calhoun Station Unit No. 1 EMERGENCY PROCEDURE EP-30 Steam Generator Tube Leak / Rupture (PPLS Unblocked)
A.
PURPOSE To describe the operator action in the event of a steam generator tube rupture / leak which results in a leak rate in excess of the available chargin'g pump capacity.
For a steam generator tube leak which is greater than the Technical Specification limit but le a than the available charging pump capacity sh'atdown the unit in ac.ordance with OP-4 or EP-32, with the following exceptions:
1.
Initiate the Site Emergency Plan to determine magnitude of off-site release.
2.
Attempt to locate and isolate the faulty /affected steam generator ASAP in accordance with this procedure; cooldown on the u_naffected n
3.
Until the faulty steam generator is isolated:
[.g a.
Ensure steam generator blowdown is secured on both
?
b.
Ensure steam is dumped to the condenser directly rather than to atmosphere if at all possible.
NOTE:
If the offsite power low signal is received when a PPLS/SIAS signal is in, the 4160V buses will load shed and resequence the safeguards loads on the diesels.
B.,
SYMPTOMS Any one or more of the following indicatons or alarms may be present:
1.
liigh Steam Generator blowdown radiation and/or isolation.
NOTE:
Increasing radiation readings may be delayed by mixing time in the Steam Generator downcomer and sample pipe transport time.
2.
High condenser of f gas radiation and/or sixth stage turbine extraction to the auxiliary steam system is isolated.
3.
Decreasing level in the Pressurizer.
4.
Decreasing pressure in the Pressurizer.
R15 5-11-82 MAY 111982 8205250183 820517 PDR ADOCK 05000285 p
EP-30-2 B.
SYMPTOMS (Continued)
(
4 5.
Standby charging pumps start.
6.
Unexplained variations in Steam Generator pressures and levels.
7.
1 I
8.
Pressurizer low-low pressure followed by SIAS actuation.
i 9.
Feedwater versus steam flow mismatch.
I 10.
Containment Isolation.
i
^
11.
VCT Level Decreasing or Low Level Alarm.
12.
Pressurizer level low or low-low with no corresponding decrease in T i
avg NOTE:
This does not include transient drop in T
""E 4
due to plant trip.
4 q
C.
ItIMEDIATE ACTION (PPLS Unblocked) 1.
Depress the manual reactor trip pushbutton.
Insure that all a
regulating and shutdown CEA's have been fully inserted and DCJ that reactor power is decreasing.
2.
Insure turbine has tripped and all stop and intercept valves closed.
3.
Insure generator breakers have tripped.
4.
If the high pressure injection system has been actuated by a low pressure signal, trip all operating reactor coolant pumps.
D.
FOLLOW-UP ACTION 1.
If Reactor Coolant Pressure is equal to or less than 1600 PSIA actuate the engineered safety features for core cooling only by placing the PPLS Test Switches on Panels AI-30A and 30B in the "PPLS TEST" position. Trip all operating reactor coolant pumps if HPI is initiated.
CAUTION:
If the of fsite power low signal is received when a PPLS/SIAS signal is in, the 4160V buses will load shed and resequence the safeguards locks on the diesels. RC pumps will be unavailable.
2.
Ensure containment isolation has taken place by verifying that containment isolation valves have gone to their accident posi-U I.
tions with particular attention to ensuring that S/G blowdown and sampling valves close.
R15 5-11-82 VsAY 1 1 1982 t
EP-30-3 D.
FOLLOW-UP ACTION (Continued)
{
3.
Ensure safety injection flow is being delivered to the reactor core by verifying high and low pressure safety injection header flows.
4.
If component cooling pump discharge pressure is greater than 133 psig or the component cooling motor amps are less than 300 amps, restore component cooling water flow to the reactor cooling pumps by placing HCV-438A, 438B, 438C and 438D control switches in the " Pull to Override" position.
5.
Monitor reactor coolant system parameters to verify natural circulation. This circulation can be verified by the following:
a.
Core exit thermocouple temperatures are stable and at least 50' below the saturation temperature for the existing RCS pressure as indicated on subcooled margin monitor, b.
Core exit thermocouples and RCS hot leg temperatures reading approximately the same.
c.
A AT across the core of not greater than 50*F; yet representative to the decay heat power level.
Immediately after a 100% power trip it is anticipated to be <20'F.
CAUTION:
Indicated water level relative to actual water
.; 2, level may be in error due to the effects of varying fluid pressure and flashing of reference leg to steam on the water level measurements.
Reference:
Technical Data Book - Steam Generator Level Correction Curves (III.3.a. -
III.3.g.).
6.
Start auxiliary feedwater pump (s) and feed steam generators I
via emergency feedwater nozzles as required to restore and I
maintain level.
l NOTE: This step should be accomplished within 15 minutes I
of the accident and must be accomplished within 30 minutes.
NOTE: Makeup EFWST from the water plant unless the condensate storage tank is flowing to the river.
7.
Implement the Emergency Plan.
Refer to EPIP-OSC-1 for emergency classification and to EPIP-OSC-2 for the method of implementing the Emergency Plan.
8.
Observe available indications to avoid a saturated steam / water system on the primary side. This will eliminate voiding in the d[IfI $* 7) core area.
Use RCS_ hot leg temperature, RCS cold leg temperature, y.
core exit thermocouples and primary system pressure to maintain ioAY 1 1 198'2 R15 5-11-82
' :______ _2_r_:
--- ' ~~ ~~
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D.
FOLLOW-UP ACTION (Continued) 8.
(Continued) the RCS at least 50 F below the saturation temperature for i
a given system pressure (See the attached saturation curve).
Other indications of system voiding are as follows:
a.
Increasing core AT; b.
Erratic steam generator d/p; c.
' Erratic RCP motor current; and d.
RCP vibration.
NOTE:
PRESSURIZER PRESSURE CONTROL USING HEATERS The pressurizer proportional heaters and one group (75 kw) from each bank of back-up heaters are available approximately 50 seconds after 480 volt load shed has occurred. To use any of the back-up heater groups the control switch must be placed in the reset position then to the required operating position.
This provides an additional 300 kw heating power. Use of these heaters is limited by diesel generator loading, ggg CAUTION:
Indicated water level relative to actual water Vs/
level may be in error due to the effects of varying fluid pressure and flashing of reference leg to steam on the water level measurements.
Reference:
Technical Data Book - Pressurizer Level Correction Curves (III.1.b.-III.1.e.).
9.
When pressurizer level indication has returned to above the heater cutoff level and pressurizer pressure is at a value corresponding to 50 F subcooling, terminate the emergency boration and proceed to EP-36 to terminate safety injection. The emergency boration should be shut down after 30 minutes to prevent boron stratification in the core.
10.
During the INJECTION PHASE a.
Ensure balanced HPSI flow to each loop (HPSI maximum design flow rate is 400 gpm/ pump). When HPSI loop valves are throttled, the primary system pressure may be reduced.
Observe system pressure during valve repositioning in relation to maintaining sstem pressure above saturation pressure. Continued operation of the HPSI system should not present an overpressurization problem as long as the RCS temperature is greater than 360 F.
Nh3TN Lb R15 5-11-82 cv MAY 111982
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D.
FOLLOW-UP ACTION (Continued) 10.
b.
Ensure balanced LPSI flow to each loop (LPSI maximum design flow rate is 2600 gpm/ pump).
It is not expected that pressure in the reactor coolant system will allow any LPSI flow.
c.
Ensure control room will remain tenable by:
- checking all access doors closed.
- Ensure that the control room ventilation system is in the filtering air makeup mode by placing the mode switch on the ventilation panel in the filtered air makeup mode.
- ensure a positive pressure exists in the control room -
don respirator protection if a positive pressure does not exist.
d.
Monitor both engineered safeguards pump room sumps for indication of excessive leakage.
Check local radiation levels before entering pump rooms.
e.
Monitor SIRWT level to ensure adequate level exists in order to prevent Recirculation Actuation Signal (RAS),
ggg since the water supplied by the Safety Injetion System is flowing out the tube break and not to the containment
~-
floor.
If SIRWT level continues to drop and it is apparent that the rupture will deplete the SIRWT inventory before the accident is terminated, start making up to the SIRWT using demineralized water and emergency boration of the SIRWT using EP-34.
Additional means of water addition may have to be initiated in order to keep up with the Safety Injection flow.
NOTE: After adequate assurance has been made that the core is being covered and cooled by safety injection and operation of the auxiliary feed-water system, cooldown and depressurization of the reactor coolant system can commence.
11.
Take manual control of the steam dump and bypass valves and continue dumping steam to the condenser until RCS temperature has been reduced at least to 482 F (cooresponds to approxi-mately 577 psia steam header pressure).
If a loss of condenser vacuum has blocked out the steam dump operation to the condenser, dump steam to.the condenser utilizing the steam seal system while observing the following limits:
a.
Maximum steam seal header pressure P-3200 of 20 psig.
)
b.
Maximum condenser pressure of 5 psig.
..d E
R15 5-11-82 BAAY 111982
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D.
FOLLOW-UP ACTION (Continued)
I 11.
(Continued) c.
One condenser vacuum pump in operation and discharge lined up to the charcoal filter in Room 59.
As a last resort (to prevent lifting of the steam generator safety valves):
Operate FW-10 off the unaffected steam generator and/or dump a.
steam to atmosphere via atmospheric dump valve HCV-1040.
CAUTION: Do not reduce RCS temperature to less than 474*F (corresponding to approximately 535 psia steam header pressure) to prevent MSIV closure.
12.
After reactor coolant system temperature has been reduced to at least 482*F commence RCS depressurization to no lower than 900 psia by performance of the following:
CAUTION:
It is imperative that RCS temperature be kept at least 50 F below the saturation temperature for the existing RCS temperature or voids may be induced in the reactor coolant system.
- g a.
Once pressurizer level has been restored to the normal
~ p<fd operating level and the core exit thermocouples and hot leg temperatures are indicated at least 50*F cooler than the saturation temperature for the existing RCS pressure, block PPLS.
b.
Supply throttled safety injection flow, monitoring pres-surizer level core exit thermocouples and hot leg temp-eratures, and reduce RCS pressure to 900 psia.
T CAUTION: Continually watch core exit thermocouples and hot leg temperatures to ensure at least 50 F subcooling of the reactor coolant below the saturation tempera-ture.
Increase safety injection flow as necessary to ensure adequate pressurizer level and core sub-cooling. See attached saturation curve.
c.
Adequate pressurizer spray is ensured if at least RC-3A and RC-3B are operating. Auxiliary pressurizer spray may i
be used to accelerate RCS depressurization.
CAUTION: No more than three RC pumps can be operated if RCS temperature is less than 500 F.
13.
Direct condenser evacuation pump discharge to the charcoal filters.
Monitor condenser vacuum carefully since this step may result in a ey es loss of condenser vacuum and the ability to dump ste.: to the condenser 1, y,i h via the steam dump system.
If it becomes apparent that condenser
, y,!
vacuum will decrease below 19" redirect condenser evacuation pump
'g
- gyg,
- ~ " "
discharge to the atmosphere.
R15 5-11-82 pfg'( 1 l 19$'2
.. ~,. _
7 7..
[]g D.
FOLLOW-UP ACTION (Continued) 14.
Once RCS temperature has been reduced to at least 482*F and RCS pressure reduced to 900 psia, close the MSIV on the "affected" steam generator.
NOTE:
Chemistry samples for boron content or activity in the secondary side may be required to determine the "affected" generator.
CAUTION:
It is very important that at least one MSIV remain open so that decay heat and RC pump heat can be dissipated and the RCS cooldown continued. Also dumping steam to the condenser is preferred over dumping radioactive contaminated steam directly to atmosphere via the atmospheric dump valve or the secondary code safeties.
15.
Af ter "affected" steam generator has been isolated, cooldown in accordance with OP-6.
16.
During LONG TERM COOLING PHASE (Procedure to flush and align ECCS to accomplish Reactor Coolant System hot leg suction and simultaneous hot and cold leg injec-tion utilizing pressurizer atxiliary spray will be pr^vided at a
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later date).
17.
See EP-35 for reset of Safeguards Lockout relays.
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Edf R15 5-11-82 MAY l 11982
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