ML17212B425

Draft off-normal Operating Procedure 0120037, Reactor Coolant Gas Vent Sys Off-Normal Operation.

ML17212B425
Person / Time
Site:	Saint Lucie
Issue date:	03/02/1982
From:	FLORIDA POWER & LIGHT CO.
To:
Shared Package
ML17212B424	List: ML17212B423 ML17212B425
References
0120037, 120037, NUDOCS 8203050249
Download: ML17212B425 (23)

Text

Page 1 of 20 FLORIDA POWER & LIGHT COMPANY STe LUCXE PLANT UNIT NO. 1 OFF-NORMAL OPERATING PROCEDURE NO. 0120037 REVISION 0

1.0 Title

Reactor Coolant Gas Vent System Off-Normal Operation 2.0 Review and Approval:

Reviewed by Facility Review Group 19 Approved by Plant Manager 19 Revision Reviewed by F R G 19 Approved by Plant Manager 19 3.0 Purpose and Discussion:

3.1 The purpose of this procedure is to provide a method of venting non-condensible gases from the Reactor Coolant System (RCS) which may inhibit core cooling during natural circulation.

3.2 Guidance and precautions are also provided for use in determining the size of the non-condensible void formation, when to initiate venting, and termination of venting operations.

4.0 Symptoms

4.1 Abnormal RCS conditions such as large variations in pressurizer level during normal charging and spraying operations have occurred.

4.2 If available, reactor vessel head temperatures equal to or greater than saturation temperature.

4.3 Plant events have occurred (such as safety injection tank fSIT}

discharge, rapid RCS cooldown, or core uncovery events) that may result in the presence of a gaseous void in the vessel head.

4.4 Loss of pressurizer pressure control during normal pressurizer conditio~s (i.e., bubble established, normal heaters/spray capabilities).

4.5 Pressurizer indicates departure from saturated conditions i.e., for a given temperature, pressure is higher than saturation pressure.

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OFF-NORMAL OPERATING PROCEDURE NO. 0120037, REVISION 0 REACTOR COOLANT GAS VENT SYSTEM OFF-NORMAL. OPERATION 5.0 Ins true tions:

5.1 .Immediate Automatic Actions:

DRAFT None 5.2 Immediate Operator Actions:

5.2.1 If any of the above listed symptoms have occurred or it is suspected that there is a non-condensible void formation present in the RCS by other detection means, then any changes being made to the primary system should be terminated and a steady state condition should be established.

5.3 Subsequent Operator Actions:

Note: Asterisked steps are not applicable if safety infection has been initiated.

5.3.1 Attempt to recombine any condensible gases by increasing RCS pressure through the use of pressurizer back-up heaters. If this step is successful in condensing the gas volume inthe vessel head (as indicated by a return to normal readings in those parameters used to determin'e the presence of the gases) then return to the appropriate operating procedures.

5.3.2 Coordinate with appropriate on-site technical resources.

(Technical Support Center [TSCl Supervisor if manned; Chemistry Department representative if TSC is not manned).

5.3.3 Determine the magnitude/size of the void formation per Appendix .B, if possible.

5.3.4 Determine the recommended venting time required per Appendix C, if possible.

5.3.5 Increase the RCS sub-cooling to 50o F + inaccuracies by either pressurizing via pressu'rizer backup heaters or decreasing RCS temperature via dumping steam.

5'3.6 Terminate containment purge, if in progress. Start all available containment coolers.

5.3.7 Ensure that.all available hydrogen recombiners are in service.

5.3.8 Verify that Chemistry Department is prepared for monitoring the containment atmosphere for hydrogen via the hydrogen analyzer and/or grab sample.

5.3.9 Increase pressurizer level to 80-85% in preparation for venting. This should provide inventory to displace approximately 900 ft3 before reaching heater level.

I OFF-NORMAL OPERATING PROCEDURE NO. 0120037, REVISION 0 REACTOR COOLANT GAS VENT SYSTEM OFF-NORMAL OPERATION Page 3 of 20

5.0 Instructions

(continued) DRAFT

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5.3 (continued) 5.3.10 If not already performed, manually block SIAS if the permissive is energized during the venting process.'.3.11 Restore power to the RCGVS solenoid operated Valves by inserting fuses 26F2 & 4 and 11F2 & 4.

C.R.A.C. PANEL 1 C.R.A.Co PANEL 2 llF2 & 4 26F2 & 4 V-1442 V-1441 V-1444 V-1443 V-1445 V-1446 V-1449 5.3.12 Monitor pressurizer pressure and level during the venting period and minimize the pressure and level decrease by selective use of charging pump combinations and letdown flow.

5.3.13 Observe the pressurizer level trend during the reactor vessel venting and, from the following conditions, determine the probable status of the reactor coolant system:

a. Controllable pressurizer level gaseous voids exist in the RCS other than the reactor vessel head or pressurizer.

The orifice in the head vent is sized to limit water relief to within the make-up capability of one charging pump (44 GPM 8 2250 psia) . Therefore, if no gases are present in the vessel head, then the pressurizer level should remain controlable.

b. Decreasing pressurizer level. gaseous voids exist in the reactor vessel head.

The venting of gases will result in a rapid decrease in pressurizer level due to the mass flow rate of the gases being greater than the mass input being provided by the charging system.

r CAUTION: If pressurizer level decreases to less than 20%,

then attempt to restore level by the CVCS System (isolate letdown, max. charging). If level cannot be restored, then manually initiate safety in) ection.

Page 4 of 20 OFF-NORMAL OPERATING PROCEDURE NO. 0120037, REVISION 0 REACTOR COOLANT GAS VENT SYSTEM OFF-NORMAL OPERATION

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jRAB 5.0, Instructions: (continued)

'<.5.3 '(continued) 5.3.14 Commence venting the reactor vessel head. The flow path used is optional, and the decision as to which is used should be based on quantity of gas to be released. If recovery and processing in the waste gas system is desired, then vent to the quench tank. If quantity is large, then vent to containment atmosphere.

5.3.15 Terminate venting when:

a. TIME PERIOD DETERM1NED IN STEP 5.3.4 IS MET, OR bo PRESSURIZER PRESSURE DECREASES BY 200 PSI y OR

c. PRESSURIZER LEVEL DECREASES BELOW 25X LEVEL, OR

d. REACTOR COOLANT SUB COOLING LESS THAN 20oF +

INACCURACIES, OR

e. THE REACTOR VESSEL HEAD IS REFILLED AS INDICATED BY A DECREASE IN THE RATE OF CHANGE OF PRESSURE AND PRESSURIZER LEVELS 5.3.16 Re-establish pressurizer level and evaluate the response of the pressurizer level trend to determine if a gas bubble existed in the head. If a gas bubble existed and the venting was terminated prior to the vessel being completely refilled, then return to Step 5.3.14.

Note: If multiple venting operations are required and the containment hydrogen concentration is equal to or greater than 3 volume percent, then provisions must be made to remove or reduce the volume of hydrogen from the containment prior to re-opening the reactor vessel head vent.

5.3.17 Return to the appropriate operating procedures following successful completion of the venting of the reactor vessel head.

Page 5 of 20 OFF-NORMAL OPE TING PROCEDURE NO. 012003 , REVISION 0 REACTOR COOLANT GAS VENT SYSTEM OFF-NORMAL OPERATION 6.0

References:

6.1 C-E "Final Report on the Reactor Coolant Gas Vent System"..

7.0 Records

7.1 Completed Appendix B and C work sheets shall be retained in the plant file in accordance with QI-17/PSL-1.

Page 6 of 20 OFF-NORMAL OPERATING PROCEDURE NO. 0120037, REVISION 0 REACTOR COOLANT GAS VENT SYSTEM OFF-NORMAL OPERATION APPENDIX A PRECAUTIONS

1. This venting procedure should not be used as 'the primary means to mitigate an inadequate core cooling event.

2. Venting operations should be performed prior to the initiation of safety injection flow throttling during a Post-Loca cooldown and depressurization. During venting "full flow" SI capabilities must be .

maintained if needed.

3. Do not trip any running or start any non-operating reactor coolant pumps during venting operations.

4. Containment purge should be isolated to prevent the release of any radioactive gases to the environment.

5. All available containment air circulation equipment should be started to prevent any hydrogen from forming a gas pocket and to ensure a representative hydrogen concentration is obtained during sampling.

6. Appendix C "Venting Time Period" determines the maximum allowable time period for venting which will limit the containment hydrogen concentration to less than 3 volume percent.

Page 7 o 20 OFF-NORMAL OPER .NG PROCEDURE NO. '0120037~EVISION 0.

REACTOR COOLANT GAS VENT SYSTEM OFF-NORMA&OPERATION APPENDIX B DRAFT NON-CONDENSIBLE VOID FOE'LATION SIZING Page 1 of 3 1.0 The objective of this test is to inject a known volume of borated water into the RCS and then compare the expected results with the actual results. E 2 0 If the safety injection system is in service, then the following steps are not applicable since normal pressurizer control will not be maintained.

3.0 Establish a constant pressurizer level and pressure condition.

3.1 Isolate all RCS sample points to minimize mass inventory loss.

3.2 Coordinate with the Technical Support Center (if appropriate) to insure that operations that could affect the test will not be performed until the conclusion of this test.

4.0 Record the following parameters:

4.1 RCS Pressure RS psia 4.2 .Pressurimr Level 0/

4.3 Charging Rate GPM 4.4 RCP Seal Leakoff Flow GPM 4.5 Time 5.0 Isolate the CVCS letdown system by closing the letdown isolation valves AOV-2515 and AOV-2516.

6.0 Turn off all pressurizer heaters, and terminate any pressurizer spray.

6.1 With RCPs on, place pressurizer pressure controller HIC-1100 in manual and zero the signal.'.2 With RCPs off, secure auxiliary spray if being used .

i 7.0 Continue charging to the RCS until either:

7.1 PRESSURIZER PRESSURE INCREASES 100 PSI OR 7 ' PRESSURIZER LEVEL INCREASES 5X

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Page o OFF-NORMAL OPER NG PROCEDURE NO. 0120037 EVISION 0 REACTOR COOLANT GAS VENT SYSTEM OFF-NORMAWOPERATION APPENDIX B Page 2'f 3 8.0 Record the following parameters:

8.1 RCS pressure psia 8.2 Pressurizer level=

8.3 Time 9 0 Reinitiate CVCS letdown flow and restore normal perssurizer pressure and level control.

10.0 Calculate the initial and final pressurizer vapor space volumes.

(express X level in decimal form) 10.1 Initial vapor volume=(1-PZR level  %) X 1252 ft3 + 134 ft3 - ft3 10.2 pinal vapor volume (initial vol.) (D lta pZR level / X 1252 ft3) ft3.

11.0 Calculate the total charged volume into the RCS.

11.1 Charged volume, ft3 = (charging flow rate GPM-seal leakoff flow rate 'GPH) X Elapsed Time (min) 7.45 Cal ft 12.0 Determmine the expected pressurizer level change 12.1 Expected Delta level = (charged volume ft3) X .0667 = X 13.0 Determine the actual pressurizer level'change.

13.1 Actual Delta level - Step 8.2 Step 4.2 7 14.0 If the actual pressurizer level change is less than the expected level change then a gaseous void exists in the reactor coolant system.

15.0 Perform the following steps to determine the volume of the RCS void:

15.1 Initial .RCS Void ft3 (Init. Vapor Vol.,Step 10.1)-(Final Vapor Vol.,Ste 10.2)-(Charped Vol.,Step 11.1) 1-'nitial Pressure ressure dna 15.2 Final RCS Void ft3 (Initial RCS Void, Step 15.1) X (Initial Pressure)

(Final Pressure)

Page 9 of 20 OFF-NORMAL OPER <TING PROCEDURE NO.'012003j, REVISION 0

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REACTOR COOLANT GAS VENT SYSTEM OFF-NORMAL OPERATION APPENDIX B <RAFT Page 3 of 3 16.0 Summary 16.1 Initial PZR vapor volume= ft3 16.2 Final PZR vapor volume ft3 Difference=

16.3 Charged volume ft3 16.4 Expected Delta level 16.5 Actual Delta level Difference=

16.6 Initial RCS void ft3 16.7 Final RCS void ft3

t f, OFF-NORMAL OPERATING PROCEDURE NO. 0120037, REVISION 0 REACTOR COOLANT GAS VENT SXSTEM OFF-NORMAL OPERATION Page 10 o f 20 gpss,FT APPENDIX C VENTING TIME PERIOD Page 1 of 3 1.0 During a core uncovery event, there exists the potential for a significant amount of hydrogen generated in the core which could be trapped in the reactor vessel and released to the containment atmosphere during the venting operation. The containment hydrogen concentration is limi'ted to less than 4 volume percent to prevent a potential explosive mixture with oxygen, therefore, the amount of hydrogen that can be vented to the containment is restricted. A maximum allowable time period for venting is determined to limit the containment hydrogen concentration.

2.0 This guide assumes that the containment conditions are near normal.

3.0 Convert the containment free-volume to containment volume at standard temperature and pressure. conditions.

3.1 Note 1 Note 2 Cont. Press. 492oR

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Note 1: Delete term unless containment pressure is greater than 2 PSIG.

Note 2: Temperature in degrees Rankine (o F + 460) 4.0 Determine containment hydrogen concentration in volume percent units.

4.1 Obtain value from Chemistry Department.

4.2 If there has been no leakage from the RCS to the containment, assume a value of zero.

4 .3 Containment H2 Concentration 5.0 Calculate the maximum hydrogen volume that can be vented to the containment which will result in a containment hydrogen concentration of less than or equal to 3 volume percent.

5.1 Max. H2 Vol, ft (3.0%-Cont.H Conc.,Step 4.3,%) X (Cont. Vol.[STP] Step 3.1) 100%

tl 6.0 Obtain from Curve 81 the hydogen flow rate which will result at the predicted RCS pressure at time of venting.

6.1 Predicted RCS pressure ~ psia 6.2 Hydrogen flow rate SCFM

Page. 11 of 20

.OFF-NORMA1, OP . ING PROCEDURE NO. 012003 , REVISION 0 REACTOR COOLANT GAS VENT SYSTEM OFF"NORMAL OPERATION APPENDIX C DRAFT Page 2'f 3 7.0 The maximum allowable venting time period which will limit the containment hydrogen concentration to ( 3 volume percent is determined by:

7.1 Step 5.1 Venting period, mins. = H2 << Volume,

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page 13 of 20 OFF-NORMAL OPE TING PROCEDURE NO. 012003 , REVISION 0 REACTOR COOLANT GAS VENT SYSTEM OFF-NORMAL OPERATION FIGURE 1 PRESSURIZER VENT-HYDROGEN PLOW RATE vs. PRESSURE CD CD CD Cd CD CD CD CD CD

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Page 14 .of 20 OFF-NORMAL OP TING PROCEDURE NO. 01200 .,

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Page 15 a f 20 OFF-NORMAL OPERATING PROCEDURE NO. 0120037, REVISION 0 REACTOR COOLANT GAS VENT SYSTEM OFF NORMAL. OPERATION FIGURE 3.

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Page 16 of 20 OFF-NORMAL OPEk ING PROCEDURE NO. 0120037, REVISION 0 REACTOR COOLANT GAS VENT SYSTEM OFF-NORMAL OPERATION FACT SHEET SOURCES OF NON-CONDENSIBLES Volume Source <nv>, Mass

1. Complete oxidation of clad (hydrogen) 448000 f't3 2514.8 lbsa

2. Fuel rod fill gas (helium) 1140 ft3 12.7. lbs

3. Fission gases (Xe, Kr, I2) 26 ft3 9.0 lbsa

4. Safety injection tanks (nitrogen)

a. Cover gas 51820 ft3 4042.2 lbsb

b. Dissolved gas 690 ft3 53.8 lbs 5 ~ Dissolved in refueling water tank (air) 1360 ft3 109.7 lbsc

6. Dissolved in primary coolant (hydrogen) 384 ft 2.2 lbs

7. Pressurizer vapor space (hydrogen) 793 ft3 4.6 lbs

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NOTES For breaks requiring the return to natural circulation no fuel rod rupture or oxidation is predicted. Numbers are based on 36924 fuel rods.

b. For breaks requiring the return to natural circulation the SIT's do not inject water.

c. The largest amount of liquid injected from the refueling water tank (RNT) during the boiling phase for breaks that return to natural circulation is approximately 40% of the RWT volume.

Pressurizer Volume of Top Spherical Head ~134 ft3 Volume of Bottom Spherical Head 114 ft3 Volume of Cylinder Section ~1252 ft3 Level Span ~350 inches Volume vs.  % Span ~15 ft3 per %

Inches vs.  % ~3.6" per %

Volume Required to Cover'Heaters -266 ft3 Pressurizer O.D. ~106.5 inches Pressurizer I.D. 96 inches Pressurizer Cross Sectional Area ~50.27 ft Steam Generators Total Volume of U-Tubes ~1147 ft3 Volume of S/G Cold Plenum ~250 ft3 Volume of S/G Hot plenum ~258 ft3

A Page 17 of 20 OFF-NORMAL OPERATING PROCEDURE NO. 0120037, REVISION 0 REACTOR COOLANT GAS VENT SYSTEM OFF-NORMAL 'OPERATION PRESSURIZER LEVEL (%) VS. VOLUME PRESSURIZER at 2250 psia/653o (Cu F.

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