ML20024A444

Rev 2 to 2-0120037, Reactor Coolant Gas Vent Sys Off-Normal Operation.

ML20024A444
Person / Time
Site:	Saint Lucie
Issue date:	06/06/1983
From:	FLORIDA POWER & LIGHT CO.
To:
Shared Package
ML20024A433	List: ML20024A432 ML20024A436 ML20024A440 ML20024A444
References
2-0120037, 2-120037, NUDOCS 8306170304
Download: ML20024A444 (15)

Text

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FLORIDA POWER & LIGHT COMPANY ST. LUCIE UNIT 2 0FF-NORMAL OPERATING PROCEDURE NO. 2-0120037 REVISION 2

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1.0 TITLE

REACTOR COOLANT GAS VENT SYSTEM OFF-NORMAL OPERATION 2.0 REVIEW AND APPROVAL:

Reviewed by Facility Review Group March 17 1982 Approved by C. M. Wethy Plant Manager March 17 1982 Revision 2 Reviewed by FRG /b /7 19 g Approved by d h b fLtAA.~t' h%1antManager #Nku4 / 719 N v

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 when to initiate venting and termination of venting operations.

4.0 SYMPr0MS

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

4.2 Reactor vessel level display less than 100% and reactor vessel head temperatures equal to or greater than saturation temperature, as indicated by QSPDS Display System.

4.3 Plant events have occurred (such as Safety Injection Tank (SIT]

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 conditions (i.e., bubble established, normal heaters / spray capabilities).

"FOR INF0[tMATION %A. *=Ive use, ONLY fn gar,ws u A re='-

verily information with a contre!!ed document.j

Pega 2 of 14 ST. LUCIE UNIT 2 ,

OFF-NORMAL OPERATING PROCEDURE No. 2-0120037, REVISION 2 V GAS VENT SYSTEM OFF-NORMAL OPERATION REACTOR COOLA.T ,

i

5.0 INSTRUCTIONS

j 5.1 Immediate Automatic Actions:

None  ;

5.2 Immediate Operator Actions:

None 5.3 Subsequent Operator Actions:

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

5.3.1 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 established.

5.3.2 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 in the vessel head (as indicated by a return to normal readings in those parameters used to determine the presence of the gases) then return to the appropriate operating procedures.

5.3.3 Coordinate with appropriate on-site technical resources (Technical Support Center [TSC] Supervisor, if manned; Chemistry Department representative if TSC is not manned).

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

5.3.5 Increase the RCS sub-cooling to 500F + inaccuracies by either pressurizing via Pressurizer Backup heaters or decreasing RCS temperature via dumping steam.

5.3.6 Terminate Containment purge, if in progress. Start all available Containment Fan Coolers.

5.3.7 Ensure that all available Hydrogen Recombiners are in se rvice.

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

4 5

4 1

P:ga 3 of 14 ST. LUCIE UNIT 2 0FF-NORMAL OPERATING PROCEDURE NO. 2-0120037, REVISION 2 -

REACTOR COOLAVr GAS VENT SYSTEM OFF-NORMAL OPERATION

5.0 INSTRUCTIONS

(continued) 5.3 (Cont.)

• 5.3.9 Increase Pressurizer level to 80-85% in preparation for ~~~1 venting. Thisshoulgprovideinventorytodisplace approximately 900 ft before reaching Pressurizer heater level.

• 5.3.10 If not already performed, manually block SIAS if the permissive is energized during the venting process.

5.3.11 Restore power to the Reactor Coolant Gas Vent System (RCGVS) solenoid operated valves by inserting fuses.

PLANT AUXILIARY CONTROL BOARD NO. 2 SA DC F1 and F2 SB DC F1 and F2 V-1462 V-1463 V-1461 V-1460 V-1465 V-1464 V-1466 5.3.12 Monitor Pressurizer pressure and level and QSPDS reactor

. vessel display during the venting period. Minimize the pressure and level decrease by selective use of Charging Pump combinations and letdown flow.

I PRECAUTIONS

1. This venting procedure should 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 A " Venting Time Period" determines the maximum allowable time period for venting which will limit the Containment hydrogen concentration to < 3 volume percent.

l Y

Pcg2 4 of 14 ST. LUCIE UNIT 2 0FF-NORMAL OPERATING PROCEDURE NO. 2-0120037, REVISION 2 REACTOR COOLANT GAS VENT SYSTDI 0FF-NORMAL OPERATION ,e h

5.0 INSTRUCTIONS

(continued) /

5.3 (Cont.)

5.3.13 Destination of the gas when venting is optional. The _

decision as to which is used should be based on quantity of gas to be released. If recovery and processing to the waste gas system is desired, then vent to quench tank. If quantity is large, then vent to containment atmosphere via accumulator to ventilation system. /R2 5.3.14 Under no circumstances should both vent valves in the venting flowpath be powered from the same electrical train. The reactor vessel head and pressurizer should not be vented simultaneously.

5.3.15 Commence venting as follows:

5.3.15.1 Venting pressurizer or reactor vessel head to containment.

Open V1460 to vent pressurizer, or Open V1463 to vent reactor vessel head Open V1465 containment isolation to commence venting 5.3.15.2 Venting pressurizer or reactor vessel head to quench tank.

Open V1461 to vent pressurizer, or Open V1462 to vent reactor vessel head Open V1464 quench tank isolation to commence venting

5.3.15.3 Venting pressurizer or reactor vessel head to accumulator. -

Open V1461 to vent pressurizer, or Open V1462 to vent reactor vess21 head Open V1466 accumulator isolation to commence venting

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Pcgs 5 of 14 ST. LUCIE UNIT 2 0FF-NORMAL OPERATING PROCEDURE NO. 2-0120037, REVISION 2 REACTOR COOLAY. r GAS VENT SYSTEM OFF-NORMAL OPERATION [m

5.0 INSTRUCTIONS

(continued)

%=

j 5.3 (Cont.)

/

5.3.16 Terminateventingbyclosingdestinationvalveandtheni i closing source valve when: 'g 1.

TIME PERIOD DETERMINED IN STEP 5.3.4 IS MET, V'-

E

2. PRESSURIZER PRESSURE DECREASES BY 200 PSI, E

3. PRESSURIZER LEVEL DECREASES BELOW 25% LEVEL, E

4. REACTOR COOLANT SUBC00 LING is <20*F + INACCURACIES, E

5. THE REACTOR VESSEL HEAD IS REFILLED AS INDICATED BY QSPDS REACTOR VESSEL LEVEL DISPLAY.

5.3.17 Re-establish Pressurizer level and evaluate the response and trend of the Pressurizer level to determine if a gas bubble existed in the head. If a gas bubble existed and the venting was termintted prior to the vessel being completely refilled, then return to Step 5.3.13.

NOTE: If multiple venting operations are required and the Containment hydrogen concentration is > 3 volume pe rcent , 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.

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

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Pego 6 of 14 ST. LUCIE UNIT 2 0FF-NORMAL OPERATING PROCEDURE NO. 2-0120037, REVISION 2 <

REACTOR COOLANT GAS VENT SYSTEM OFF-NORMAL OPERATION , f

6.0 REFERENCES

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

7.0 RECORDS REQUIRED:

7.1 Completed Appendix A work sheets shall be retained in the plant files in accordance with QI-17/PSL-1.

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. Paga 7 of 14 ST. LUCIE UNIT 2 1 0FF-NORMAL OPERATING PROCEDURE NO. 2-0120037, REVISION 2 REACTOR COOLANT GAS VENT SYSTEM OFF-NORMAL OPERATION i

( m APPENDIX A VENTING TIME PERIOD Page 1 of 3 i

1. During a core uncovery event, there exists the potential for a significant amount of hydrogen'to be generated in the reactor core which could be trapped in the reactor vessel and released to the Containment atmosphere during the venting operation. The. Containment hydrogen concentration is limited to <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 Containacnt hydrogen '

concentration.

2. This guide assumes that Containnent conditions are near normal.

3. Convert the Containment free-volume to Containment volume at standard temperature and pressure conditions as follows:

IContainmenI ~~ ~'

Pressure a 4920R Congainment Volume = (2.5 X 10 6

ft 3) X l 14.7 X l

.(Containment (ft @ STP) b

[_ _

[_ Temperature _ ,

N0fES: a. Delete terr. if Containment pressure is < 2 PSIG.

b. Temperature in degrees Rankine (* F + 460)  ;

Containment Volume (ft3 @ STP) = . ,

4 f

4. Determine Containment hydrogen concentration in volume percent unicab ,

~ '

A. Obtain value from Chemistry Department.  ;

B. If there has been no leakage from the RCS into the Containment,'

assume a value of zero. '

C. Containment Hydrogen Concentration =  %.

- l S. Calculate the maximum hydrogen volume that can be vented to the '

Containment which will result in a Containment hydrogen concentration of 4 j[ 3 volume percent. , i , .

> 1 M

' aximum Hydrogen Volume (f3 t )=(3.0%-Cont.H 7 Conc % [ Step 4.Cl)X(Cont. Vol.@STP.(Ster.31(

100%

Maximum Hydrogen Volume3(ft ) ,,, ,

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Paga 8 of 14 ST. LUCIE UNIT 2 r

OFF-NORMAL OPERATING PROCEDURE NO. 2-0120037, REVISION 2 REACTOR COOLAVP GAS VENT SYSTEM OFF-NORMAL OPERATION F'

APPENDIX A VENTING TIME PERIOD Page 2 of 3

6. Obtain from Curve #1 the hydrogen flow rate which will result at the predicted RCS pressure at time of venting.

A. Predicted RCS pressure = psia B. Hydrogen flow rate = SCFM

7. The maximum allowable venting time period which will limit the containment hydrogen concentration to 1 3 volume percent is cetermined by:

Max. H, Volu:ne (Step 5' Venting period (min) = H 2 Flow rate { Step 6 Venting period = minutes i

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Pegs 9 of 14 ST. LUCIE UNIT 2 0FF-NOR!fAL OPERATING PROCEDURE NO. 2-0120037, REVISION 2 REACTOR COOLANT CAS VENT SYSTD! 0FF-NORMAL OPERATION APPENDIX A 1

Page 3 of 3 '

f CURVE #1. i f Q' HYDROGEN FLOW RATE vs. PRESSURE --

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Pcgs 10 of 14 ST. LUCIE UNIT 2 0FF-NORMAL OPERATING PROCEDURE NO. 2-0120037, REVISION 2 REACTOR COOLANT GAS VER SYSTEM OFF-NORMAL OPERATION ,

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Pega 11 of 14 ST. LUCIE UNIT 2 0FF-NORMAI, OPERATING PROCEDURE NO. 2-0120037, REVISION 2 REACTOR COOLANT GAS VENT SYSTEM OFF-NORMAL OPERATION '\

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FIGURE 3 L. .

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Pega 13 of 14 ST. LUCIE UNIT 2 0FF-NORMAL OPERATING PROCEDURE NO. 2-0120037, REVISION 2 REACTOR COOLANT GAS VENT SYSTEM OFF-NORMAL OPERATION FACT SHEET SOURCES OF NON-CONDENSIBLES VOLUME j SOURCE _(STP) MASS

1. Complete oxidation of clad (hydrogen) 448000 ft3 2514.9 lbsa a

2. Fuel rod fill gas (helium) 1140 ft 3 12.7 lbs

3. Fission gases (Xe, Kr, I )

2 26 ft3 9.0 lbs a

4. Safety Injection Tanks (nitrogen)

A. Cover gas 51820 ft3 4042.2 lbs b B. Dissolved gas 690 ft 3 53.8 lbs b

5. Dissolved in Refueling Water Tank (air) 1360 ft3 109.7 lbsc

6. Dissolved in primary coolant (hydrogen) 3 384 ft 2.2 11bs

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

a. 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 (RWT) during the boiling phase for breaks that return to natural I circulation is approximately 40% of the RWT volume.

Pressurizer Volume of Top Spherical Head = 134 ft3

. Volume of Bottom Spherical Head = 114 ft 3 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 0.D. =

106.5 inches Pressurizer I.D. = 36 inches Pressurizer Cross Sectional Area = 50.27 ft 2 Steam Generators Total Volume of U-Tubes = 1147 ft3 Volume of Steam Generator Cold Plenum = 250 ft 3 Volume of Steam Generator Hot Plenum = 258 ft3

Pega 14 of 14 ST. LUCIE UNIT 2 0FF-NORMAL OPERATING PROCEDURE NO. 2-0120037, REVISION 2 l REACTOR COOLANT CAS VENT SYSTEM OFF-NORMAL OPERATION (

PRESSURIZER LEVEL (%) vs. VOLUME (Cu Ft)

PRESSURIZER at 2250 psia /653*F l

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