ML20054K031

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Offnormal Event Procedure 05-1-02-V-13, Hydrogen Explosion in Offgas Sys,Safety-Related, Revision 11
ML20054K031
Person / Time
Site: Grand Gulf  Entergy icon.png
Issue date: 06/12/1982
From:
MISSISSIPPI POWER & LIGHT CO.
To:
Shared Package
ML20054J949 List:
References
05-1-02-V-13, 5-1-2-V-13, NUDOCS 8206300317
Download: ML20054K031 (4)
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Text

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C PLANT OPERATIONS MANUAL 6

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Volume 05 05-1-02-V-13 Section 02 Revision: 11

! Date: 6-12-82 i

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1 l OFF-NORMAL EVENT PROCEDURE 1

i HYDROGEN EXPLOSION IN THE OFF GAS SYSTEM

, SAFETY RELATED

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Prepared: // ep_ -

Reviewed: - /f jv Nuclear Plant Ouality Sup"erintetident dicW Review Approved: Q ,

Oper ior Superinte en

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List of Effective Pages:

Page:

1-3 List of TCN's Incorporated:

Revision TCN No.

10 None 11 None 8206300317 820625 PDR ADOCK 05000416 P PDR

g cgAND CULF NUCLEAR STATION OFF-NORMAL EVENT PROCEDURE

Title:

Hydrogen Explosion in No.: 05-1-02-V-13 Revision: 11 Page: 1 the Off Cas System I

1.0 PURPOSE / DISCUSSION The purpose of this pr ocedure is to provide instructions to the operator

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to minimize the releate of radioactive material into'the atmosphere, and
to extinguish fires it the off Fas system following a hydrogen. explosion' in the off gas system. >

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1.2 This procedure may in:erface with the Emergency' Plan.  !'

1.3 When the hydrogen concentration increases to foer ' percent or greater <in the off gas system, an explosive mixture is present and thcl possibility

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i of a hydrogen ignition or explosion will' exist. An er.plorlon may damage, components or piping and open the system to atmosphere resulting ih the '

release of radioactive materials. A hydrogen explosion or. , ignition may also result in the i nition t of the activated charcoal in'the(adsorber ~

beds which will cause an increase in the charcoal adsorber,l ed [ <

temperature ' and the c ff gas post radiation Jev'e1.

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.!4 2.0 SYMPTOMS 1

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2.1 -Momentary high differentTal alarms 1H13-P84NcK~the p'relilters and# s' -

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afterfilters. ,

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! 2.2 Fluctuating preheater inlet pressures 1H13-PP45. '

2.3 Fluctuating of f gas system flow rates out of the chr.rcoal adsorber ^

. beds 1H13-P845. - --- - -

2.4 Of f gas activity out of the charcoal adsorbers' is increasing on 1H13-P604. -, y 4

2.5 Rumbling sound originating from the of f- gas syst9m or, piping in the '

l turbine building or the of f gas section of the radwaste building.

2 . 6, Increasing temperatures in the charcoal teds or the' charcoal adsorber, _

vessel walls on 1H13-P845.

2.7 Area monitors in the turbine building or the of f gas section of the radwaste building increasing or alarming on 1H13-P844. '

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2.8 Carbon Vault High Radiation annunciator, ,

2.9 Decrease in SJAE flow and increase in SJAE temperature, on computer t points N62-N025A or N025B.

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l CRAND GULF NUCLEAR STATION OFF-NORMAL EVENT PROCEDURE

Title:

Hydrogen Explosion in No.: 05-1-02-V-13 Revision: 11 Page: 2 the Off Gas System ll i

3.0 AUTOMATIC ACTIONS 3.1 If the of f gas pos t treatment radiation levels increase to the Hi-Hi-Hi setpoint the following actions will occur:

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I 3'.1.1 F060, OFF GAS DISCHARGE TO VENT Closes 3.1.2 F054, PREFILTER INLET DRAIN Closes 3.1.3 F034A(B), CONDENSER DRAIN A(B) Closes j 3.1.4 F023, HOLDUP LINE DRAIN Closes.

I 3.2 These valve closures will ultimately result in a loss of condenser vacuum i and turbine trip.

4.0' IMMEDIATE OPERATOR ACTIONS /#

4.1 Verify that the Off Gas Isolation has occurred if appropriate.

the standby charcoal adsorber Train, if' not already in - Ws . .

t 4.2 ___is~to Shi service.

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l Reduce reactor power as necessary to reduce post treatment radiation levels below the Hi-Hi-Hi setpoint. _

4.3 Reset the post treatment radiation Hi-Hi-Hi and verify that of f gas flow is restored. _ -- -

4.4 If flow cannot be restored, scram the reactor and refer to ONEP's 05-1-02-I-1, Reactor Scram, 05-1-02-I-2, Turbine and Generator Trips, and 05-1-02-V-8, Loss of Condenser Vacuum.

g: 4.5 Evacuate personnel from areas of high radiation levels and notify Health 4

Physics to perform surveys of the area.

4.6- Inform Shif t Supervisor or Shift Superintendent of plant conditions.

-. . s 5.0 SUBSEQUENT ACTIONS 5.1 Check the off gas system parameters for temperature increases, flow decreases, and pressure changes that would indicate that a substained -

combustion is present in the system.

5.2 If radiation nonitors or Health Pysics surveys indicate that the Off Gas System is open to atmosphere, refer to ONEP 05-1-02-II-2, off Gas Activity High.

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a ERAND CULF NUCLEAR STATION OFF-NORMAL EVENT PROCEDURE

Title:

Hydrogen Explosion in No.: 05-1-02-V-13 Revision: 11 lPage: 3 the Off Cas System I

i 5.3 Check the hydrogen concentration of the off gas out of the recombiner If an explosive mixture is present, intiate an air purge on the train.

recombiner train to reduce the concentration.

t 5.4 After the hydrogen concentration has been reduced below 4% and if a I

reconbiner malfunction is suspected, shif t to the standby recombiner train in accordance with SOI-04-1-01-N64-1. -

5.5 If charcoal bed or charcoal adsorber vessel wall temperatures on the j secured adsorber train are increasing, isolate the secured train and I initiate a nitrogren purge on the train in accordance with g SOI-04-1-01-N64-1.

i 5.6 If filter D/P's indicate a damage filter, shift to the standby filter.

5.7 If system parameters indicate other components are damaged, shif t to the standby ccmponents as necessary. r#

5.8 If the fire cannot be extinguished or the off gas system cannot operate

_propply due to damaged-components, initiata a-reactor shutdown-in -

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accordance with I0I 03-1-01-2, Power Operations. <- .

5.9 If the fire is determined to be extinguished and the system is not damaged, resume plant operation. Closely monitor system temperatures for an increase that would indicate' that the fire was not completely extinguished.

5.10 Proceed to Unplement 10-S-01-1, Activation of the Emergency Plan, if directed by the Shift Supervisor or Shift Superintendent.

5.11 Observe Radiological Effluent Technical Specifications 3.11.2.1 Caseous g Effluents.

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