ML20054B804

Suppl to Small Break Operating Guidelines

ML20054B804
Person / Time
Site:	Davis Besse
Issue date:	04/30/1982
From:	BABCOCK & WILCOX CO.
To:
Shared Package
ML20054B802	List: ML20054B801 ML20054B804
References
TASK-2.B.1, TASK-TM 69-1106003, 69-1106003-00, TAC-44364, NUDOCS 8204190213
Download: ML20054B804 (13)

Text

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Docket No. 50-346 Revised by Toledo Edison License No. NPF-3 April, 1982 Serial No. 804 April 13, 1982 E 25i [l h (%

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NUCLEAR ENGNEERiNG

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a SUPPLEMENT TO DAVIS-BESSE UNIT 1 t

SMALL BREAK OPERATING GUIDELINES Document #69-1106003-00 l

B&W Document ID No.

l 77,-1130302-00 f

I Prepared by i

Babcock & Wilcox Company Nuclear Power Generation Division I

Lynchburg, Virginia 8204190213 820413 PDR ADOCK 05000346 P

PDR

Supplement to Davis-Besse Unit 1 Small Break Operating Guidelines Doc. 69-1106003-00 4

l Inadequate Core Cooling Use of High Point Vents Conditions:

1.

Inadequate core cooling is occurring, M

i 2.

Core exit thermocouple temperature is greater than curve 1 of figure 3 (Tclad 2 1400*F).

Required Actions for Use of High Point Vents:

I 1.0 Open hot leg high point vent valves, RC-4608A, RC-4608B, RC-4610A, and RC-4610B.

1.1 If the RCS depressurizes to less than 150 psig:

a.

Close high point vent valves, RC-4608A, RC-4608B, RC-4610A, and RC-4610B.

b.

Go to " Appendix A - LPI Cooling" of the Small Break Operating Guidelines.

1.2 When subcooling margin is obtained, close high point vent valves, RC-4608A, RC-4608B, RC-4610A, and RC-4610B.

1.3 If RC pressure remains above 150 psig, continue cooldown.

Follow Section 2.0 of this supplement if further use of vents is required.

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1.0-1.3

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INADEQUATE CORE COOLING USE OF HIGH POINT VENTS 1.0 OPEN HPV VALVES RC-4608 A&B, RC-4610 A&B v

1.1 RCS DEPRESSURlZES T ypg LESS THAN 150 PSIG 1r A.

CLOSE HIGH POINT VENT g) 1.2 VALVES. RC-4608A&B, 3r WHEN SUBC00 LING MARGIN OBTAINED.

RC-4610A&B

.CLOSE HPV VALVES RC-4608A&8 &

B.

GO TO APPENDIY a 0F SB00 RC-4610A&B 1.3 IF RC PRESSURE REMAINS l

ABOVE 150 PSIG, CONTINUE C00LOOWN

Post Accident Refill Use of Hot Leg High Point Vents Conditions:

1.

Saturated conditions have occurred in the RCS, AND 2.

HPI is maintaining RC pressure greater than the required pressure for LPI operation, AND 3.

RC pumps are not available, AND 4.

Natural circulation has not been established or has stopped (e.g., RCS refill).

j Required Actions for Use of High Point Vents:

l 2.0 Open all hot leg high point vent valves, RC-4608A, RC-4608B, RC-4610A and RC-4610B.

2.1 If the RCS depressurizes to less than 150 psig:

Close all hot leg vent valves, RC-4608A, RC-4608B, RC-4610A and RC-4610B.

a.

b.

Go to " Appendix A - LPI Cooling" of the Small Break Operating Guidelines.

2.2 When natural or forced circulation is established as indicated by:

a.

T nd core exit thermocouple (average of 5 highest) becoming subcooled by hot subcooling margin and decreasing.

AND t

b.

Core exit thermocouples temperature decreases when secondary pressure is decreased.

Close all hot leg high point vent valves, RC-4608A, RC-4608B, RC-4610A and RC-4610B.

NOTE:

If natural circulation is not established, the Small Break Operating Guide-lines will direct further actions.

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2.3 Go to Step 3.0 if forced flow is not established and a bubble has forced in the vessel head as indicated by a loss of pressure control, otherwise continue with plant cooldown.

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2.0 2.3 OST ACCIDENT REEILL USE OF HOT LEG HIGH POINT VENTS 2.0 y

OPEN All HOT LEG HIGH POINT VENT VALVES, RC-4608A, RC 46088, RC-4610A &

RC-4610 B r

RCS EPRESSURIZES TO YES LESS THAN 150 PSIG v

A.

CLOSE ALL HOT LEG VENT NO

2. 2 VALVES RC-4608A,RC-46088,

,F RC-4610A & RC-46108 WHEN NATURAL CIRCULATION. or forced circulation is established, close hot B'

GO TO APPEN0lX "A" 0F SB0G leg vent valves RC-4608A, RC-4608B, RC-4610A.& RC-4610B

2. 3 y

BUBBLE EXISTS IN THE RV HEAD AS CONTINUE WITH PLANT DETERMINED BY THE LOSS OF PRESSURE NO CONTROL YES ir GO TO STEP 3.0

Use of High Point Vents to Cooldown the RCS With Steam or Gas in the Reactor Vessel (RV) Head Conditions:

Steam has accumulated in the RV head as indicated by a loss of pressure control (i.e., RC pressure does not decrease significantly despite spraying the pressurizer or opening PORV).

Required Actions to Cooldown:

3.0 Establish subcooling margin on T and T indication with MU or HPI flow.

hot cold 3.1 If pressurizer level indicates off-scale high or unreliable, then go to Step 4.0, otherwise continue.

If in any of the following steps, pressurizer level indicates off-scale high or unreliable, go to Step 4.0.

3.2 Open hot leg high point vents and pressurizer vents, RC-4608A, RC-4608B, RC-4610A, RC-46108, MOV-239A and MOV-200.

3.3 Attempt to restore normal pressurizer level (>100") with MU or HPI flow.

3.4 Throttle HPI flow to depressurize the RCS at a rate to maintain natural circulation flow and subcooling margin.

3.5 If natural circulation stops a.

Close pressurizer vents (MOV-239A and MOV-200).

b.

Stop depressurization.

When natural circulation is regained, open pressurizer vents (MOV-239A, MOV-200),

c.

repeat Step 3.4 and depressurize at a slower rate..

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3.0 3.6 COOLDOWN RCS WITH STEAM OR GAS IN l

THE RV HEAD 3.0 y

ESTABLISH-SUBC00 LING MARGl DN T AND T INDICATION H

C WITH HPl FLOW r

3.1 PZR LEVEL INDICATES YES 0FF-SCALE HIGH OR GO TO STEP 4.0 UNRELIABLE N0 3.2 v

OPEN HOT LEG HIGH POINT VENTS.AND PZR VENTS RC-460B A, RC-46088, RC-4610A, RC 46108, MOV-239A &

MOV-700 3.3 y

ATTEMPTTORESTORgRMALPZR LEVEL (>100") WITH API FLOW r

3.4 y

THROTTLE HPI FLOW TO DEPRESSURIZE THE RCS AT A RATE TO MAINTAIN NATURAL CIRCULATION AND SUBC00 LING MARGIN A. CLOSE.MOV-239 A &

l MOV-200

8. STOP.0EPRESSURIZATION 3.5 NATURAL C. REGAIN NATURAL YES CIRCULATION OPEN MOV-CIRCULATION y

239A & MOV-200. THEN l

STOPS REPEAT STEP 3.4 AT A DECREASE 0 NO

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FlATE 3

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3.6 If subcooling margin cannot be maintained a.

Close pressurizer vents (MOV-239A and MOV-200).

1 b.

Stop the depressurization.

c.

When subcooling margin is re-established, open pressurizer vents (MOV-239A, MOV-200), and repeat Step 3.4.

3.7 Continue depressurization.

When forced circulation is established, using RC pumps or the DER pumps, close MOV-239A, MOV-200, RC-4608A, RC-4608B, RC-4610A and RC-4610B.

The preferable mode of using the DHR pumps is through valves DH11 & DH12. Other alternative is the recirculation from the sump.

3.8 Continue with plant cooldown.

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L 3.6-3.B m

3. 6 l

NO SUBC00 LING MARGIN 1r I_

A.

CLOSE PRESSURIZER VENTS YES (MOV 239A AND MOV-200)

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3. 7 Y

B.

STOP THE DEPRESSURIZATION

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CONTINUE DEPRESSURlZATION.

C.

RE ESTABLISit j

WHEN FORCED CIRCULATION IS ESTABLISHED SUBC00 LING MARGIN THEN OPEN CLOSE MOV-239A. MOV-200, RC-4608A.

MOV-200 AND MOV-239A ANO RC-4608B, RC-4610 A ANO RC-4610B b

REPEAT STEP 3.4 m

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3.B

,r CONTINUE PLANT C00LOOWN 1

1 Use of High Point Vents to Cooldown the RCS Without Pressurizer Level Indication and With Bubble in RV Head Conditions:

1.

RCS pressure stabilized after the loops have been refilled AND 2.

Pressurizer level indication is not reliable QR 3.

Pressurizer level indication is off-scale high.

Required Actions to Cooldown:

4.0 Open hot leg high point vent valves RC-4608A, RC-4608B, RC-4610A and RC-4610B.

4.1 Throttle HPI/MU flow to depressurize the RCS at a rate to maintain natural circulation flow and subcooling margin.

If at any point natural circulation is lost, open the hot leg high point vents immediately.

4.2 Continue depressurization.

When forced circulation is established, using RC pumps or the DHR pumps, close RC-4608A, RC-4608B, RC-4610A and RC-4610B.

4.3 Continue with plant cooldown.

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COOLDOWN OF THE RC l

WITHOUT PZR LEVEL

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INDICATION AND WITH BUBBLE IN RV HEA 4.0 v

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OPEN HOT LEG HIGH POINT VENTS RC-4608 A, RC-46088, RC-4610 A,

h RC-4610B 4.1

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THE RCS AT A RATE TO MAINTAIN THROTTLE HPl/' FLOW TO DEPRESSURIZE h_-

NATURAL CIRCULATION AND SU8C00 LING M ARGt9 4.2 y

CONTINUE DEPRESSURIZATION.

WHEN FORCED CIRCULATION IS ESTABLISHED CLOSE RC-4608A, RC-46088, RC-4610A AND RC-46108

4. 3 y

CONTINUE PLANT C00LOOWN 1

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LO -LOCMED OPEN REACTOR COOLANT SYSTEM HIGH PolNT VENTING FOR DB-l

Docket No. 50-346 Licenza No. NPF-3 Serial No. 804 April 13, 1982 i

Emergency Procedure EP 1202.06 r

Loss of Reactor Coolant and Reactor Coolant Pressure r

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8204190215 820413 l

PDR ADOCK 05000316 P

PDR j

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