Text

Miscellaneous Documents Re Planning 790328-0401.Info Includes Operable/Available Status & Major Sequence of Events
	ML19224B024
Person / Time
Site:	Crane
Issue date:	04/01/1979
From:	; Office of Nuclear Reactor Regulation
To:	;
References
	OSP-790401-1, NUDOCS 7906130444
	Download: ML19224B024 (63)
	v • d • e

,

50-320 Miscellaneous documents regarding planning from NRR files 3/28/79 - 4/1/79 r

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9 181 2o5 7906130NYs 6

APPENDIX 1 MAJOR SEQUENCES OF EVENTS Ma or sequences evaluated here are tied to the loss of forced circu-a lation in the RCS.

The loss of flow from the reactor coolant pump (RCP) is the generalized initiating event from which other initiating events such as loss of offsite power can develop.

l APPENDIX 1.a SEQUENCES OF POSSIBLE SYSTEMS FAILURES 4:

c f'

Figure 1.b-1 shows the loss of RCP event tree. This tree shows the b

various options available given the loss of the RCP, and indicates which combinations of ovents or failures would lead to core meltdown (CM).

The sequences c'enoted with an asterisk are those which would be ex-7-

pected to follow the core meltdown progression discussed below, leading h.

to the variety of atmospheric radioactive releases and consequences discussed later.

Some core meltdowns could be expected to be delayed o...

for roughly a week because of the availability of ECC injection over b

i4 that period.

This method of core cooling, however, is not expected to c

be adequate to prevent core melt; as such a core meltdown is assessed g.

2 to occur at roughly a week. A rough measure of relative probabilities r -

of the various outcomes is indicated by the notation of L, M, H (low,

[s medium,high).

The column on the right-hand side of the page indicates the relative probabilities of the sequences, with "LM" as the highest g

3 probability and L M as the lowest.

I P

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APPENDIX 1.b MAJOR EVENTS AND TIf11NG IN EVENT OF CORE ltELTDOWN Event 1

- Sprays and Coolers Operative Time =0 Flow stops, core and water start heat-up Time =100 min Core starts to uncover Time =150 min Core begins to nelt Time =200 min Molten core is in lower head of, eactor vessel, pressure is 2500 psia Time =210 min Reactor vessel fails, containment pressure goes to 25 psia Time =210 min Hydrogen burns, containment pressure goes to 67 psia 7

Steam explosion possibility - minor consequence ci f

CONTAINMENT SURVIVES (Failure assumed 130 psia)

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Time =10 hours Malten core has melted about 1 meter into basemat Time = days Major problem - haridle hydrogen, oxygen - maintain contain-

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ment integrity 2~

CAU~ ION:

- Keep sprays running

,~

- Keep water many feet over molten debris L

- WITHOUT RECOMBINERS Hydrogen continues to build up BASEt%T SURVIVES I*'

Event 1

Conclusion:

This event should not produce trajor releases fii t[

Event 2

- Sprays and Coolers Failed Before Flow Stops e

F.

Time =0 to Time =210 min Same as Event 1 - containment pressure is 25 psia F'

Time =810 min Containment pressure is 70 psia Time =1 day Contairiment fails due to steam (mostly) overpressure -

about 135 psia c

CONTAINMENT FAILS l-[

Event 2

Conclusion:

This event leads to major releases.

K L

e 181 29,7 4

The event tree for core melt leading to various releases is shown in Figure 1.b.

The following are essential in the event of core melt.

1.

Sprays 6nd coolers are required to prevent major releases.

2.

Hydrogen must be recombined or otherwise removed from containment.

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OPERABLE /AVAILABLE STATUS t-1.

"A" Reactor Coolant Pump running, all three others are considered operable.

l 2.

All Pressurizer Heaters operable.

3.

Pressurizer Spray operable.

b 4.

Both Decay Heat Rr.moval Pumps and their atter. dant valves are operable.

5.

Both Containner,t Spray Pumps operable.

?

6.

Four Containmeut Fan Coil Units operating, the other Unit is available.

7.

Two Nuclear Survice Water Pumps operating, the other two are available.

l 8.

Two Nuclear Services Closed Cooling Water Pumps are operating, the

,5 other is available.

k' 9.

Botn Electr ic Auxiliary Feedwater Pumps are available.

10. Borated Water Storage Tank volu:ae 200,000 gallons.

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11. Both Emergency Diesel Ur.its operable.

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12. One Hydrogen Recombiner operable, the other is being tested

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(0400 hours0.00463 days 0.111 hours 6.613757e-4 weeks 1.522e-4 months , 4/1/79).

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13. Spent ruel Pool in Unit 1 empty, Unit 2 status unavailable.

C.

14.

Sources of off-site power available.

C'.

15. Decay Heat Closed Cooling Water Pumps operable.

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E 181 299 I

APPENDIX 6 In view of the forecast over April 1-3, we used F-1 m/sec for the assumed weather.

The results are therefore conservative. The measured dose rates and actual weather should be evaluated in making the actual P

decisions.

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Major Sequences Description assump. results Backup available a.

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Things not to do if you don't have to a.

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Time of day d.

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EXPECTED PLANT RELEASE

RESPONSE

AND EVACUATION WARNING WHO

_ EVENT

( RANGE?_[

TI?1E SCENARIO TIf1E DECIDES

- Lose RCP

- Failure to reach RHR Core Melt Big Aux Split X Ci 12 X Ci Nobles Puff Release

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Immediate Precaution-a ry pl us fianda to ry if X fails 2 hr from X failure to hi public doses 181 303

2:45 a.m.

1.

Tbjor Sequences Description assumption results Backup available a.

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BACKUP PIECES OF PAPER 2.

Classes of release - description assumptions source terns a.

Large-scale core melt with continuous failure k

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Large lig leak in Auxiliary Building c.

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Alternatives Lineups L

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Action Guidelines a.

Predicted doses of 1R WB or SR Thy - standby; evacuation may De needed soon - children and pregnant women should be evac-uated.

b.

Predicted doses of SR WB or 25R Thy - mandatory evacuation of all persons.

Assumes general warning already that some form of evacuation may become necessary.

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For both a and b, above, the time span would be given if known, e.g.,

a. - may be ordered in two hours;

b. - evacuation within two hours w

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2:45 a.m.

8.

Categories of Evacuation a.

Precautionary, before undertaking sone necessary operation with sufficiently high risk to make an orderly precautionary evacuation appropriate.

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Mancatory because of risk of doses exceeding guidelines.

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_ _ _ _ _ _ _ __ _ _ _ _ ___ _ _l _ ___ W H O _ _ _.

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Major Sequences Engr.

2.

Classes of Release Engr.

(Conseq.

Check) 6 3.

Available Equipment Engr.

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4.

Alternatives Engr.

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Things Not to Do Engr.

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Weather Conseq.

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Action Guidelines Conseq.

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Categories of Evacuation Conseq.

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Scenarios e

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5:25 a.m.

7.

Action Guidelines Notify evacuation autnorities two hours in advance to standby a.

for a pussible evacuation.

b.

Predicted doses of 1R whole body or SR thyroid in 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months -

mandatory evacuation of children and pregnant women.

c.

Predicted doses of SR whole body or 25R thyroid in 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months -

mancatory evacuation of all persons.

Assumes general warning already that some form of evacuation may become necessary.

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181 313 4

April 1, 1979 f0LbTo M

This table includes a number of assumptions about activity and weather.

These assumptions have been chosen conservatively.

In an actual release, the release rate and weather should be evaluated as they are at the time, and the decision based on those values.

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Decision Sequence Event - Spontaneous failu e or decision to perform a potentially risky r.aneuver.

Find out what actually happened and what is In tables functioning (1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months )

Predict what could result - different likelihoods t

Predict release rate Assumed conetant Determine present weather and farecast in table In tabl6 Dose prediction Action Guidelines Per Appendix 7

~

Who Decides NRC decision is made by Mr. Dentcn, who is also Presidential represer.tative.

There are two carallel paths of information and analysis leading to Mr.

Denton or his representative:

4 Path 1:

NRC nan in control room - Open line to NRC Incident Response s

Center.

NRC technical peopl, at Center phone communication to 0:nton.

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Path ?: Another NRC man in Control Roam. Open line to NRC trailer, NRC technical people in trai ser.

Denton in same trailer or in communication with it.

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9 PAGE 2

EXPECTED PLANT RELEASE 1fARNING EVACUATION WHO EVENT

_ RESPONSE (RANGE?)

AND TIME TUE SCEMRIO DECIDES 2.

Core Melt Maintain Containment

Tech Spec Con-4 hour PrecaJtionary NRC recommends to.

Integrity (likely) with tainment Leak State Governor Containment Cooling Rate Evac 2 mi all around and 5 mi sec tor,**

stay inside 10 mi Containment headed for Reactor Safety 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months Evac 5 mi all Breach Study Categories around & 10 mi PWR 4 - See sector, stay Appendix inside 15 mi 3.

Hydrogen Ex-Mixture in explosive Precautionary plosion i.isice range 2 mi (?)

a Reactor Vessel No significant change No significant None Info from Control in reactor or primary change Room to NRC Re-system presentative via paths analysi., by Core Crushed (unlikely)

Core melt 2 N Rt' groups in See item 2 &

parallel Appendix 4.

Evacuate Control Loss of Controi Probably caused Evac 5 mi all Room (except by core melt around and 10

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very temporarily)

[misector**

stay inside 15

' mil es

<a N

- 90 Sector

Action Alternatives Evacuation Stay Inside 1.

2 miles 2.

2 miles 5 miles 2 miles all a ound 3*

5 miles 90 sector

'i0 milec 5 miles al' around

10 miles 90 sector 15 miles a.

All sector choices governed by wind direction.

If shifting, more than one quadrant may be affected.

b.

These are initial values; as the release continues measurements may indicate the need for reconsideration of action up to 20 miles.

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s Action Guidelines fictify evacuation authorities two hours in advance (if available) a.

to standby for a possible evacuation, b.

Predicted doses of 1R whole body or SR thyroid in 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months -

stay inside.

Predicted doses of SR whole body or 25R thyroid in 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months -

c.

mandatory evacuation of all persons.

Assumes general warning already that some form of evacuation ray become necessary.

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Weather The table is based on a conservative prediction of the weather for the next few days, based on the April 1 forecast.

At the approach to deci-sien time for evacuation, the appropriate meterological condition will be factored into the dose estimates to determine the evacuation time, sectors, and distances for the evacuation.

NRC is predicting the dispersion characteristics of the region for the currently measured meteorology as the incident progresses.

Heat Generation The reactor core is now quite cool compared to the conventional design-basis calculations.

1.

The reactor is new, so no fuel has more than 3 months equivalent operation, compared to 1-2 years average for other plants.

2.

The neutron chain reaction has been shut down for over 4 days.

It should also be noted that the concrete basemat of this plant is unusually thick.

4 -

As a result of the above differences, calculations for this plant at this time predict that the core will not melt its way through the containment.

e 7

)@j-320

APPENDIX tMJOR SEQUENCES OF EVENTS Major sequences evaluated here are tied to the loss of forced circu-lation in the RCS.

The loss of flow from the reactor cooiant pump (RCP) is the generalized initiating event from which other initiating events such as loss of of fsite poner can develop.

~

APPENDIX 1.a SEQUENCES OF POSSIBLE SYSTEMS FAILURES l

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Fig;re 1.b-1 shcws the loss of RCP event tree.

Th i s t re e s h o',,1 the f<

various options available given the loss of the RCP, and indicates which t

i ccmbina ions of events or failures would lead to core meltdown (CM).

The sequences denoted with an asterisk are those which would be ex-pected to fnllow the core meltdown progression discussed below, leading 1

l..

to the variety of atmospheric radioactive releases and consequences t

discussed later.

Some core meltdowns could be expected to be delayed L.

for roughly a v.__K because of the availability of ECC injection over i.,

that period.

This method of core cooling, however, is not expected to L

be adequate to prevent core melt; as such a core meltdown i3 assessed to occur at roughly a week.

A rough measure of relative probabilities of the various outcomes is indicated by the notation of L, M, H (low, medium,high)'.

The column on the right-hand side of the page indicates b

the relative probabilities of the sequences, with "LM" as the highest e

3 probability and L M as the lowest.

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IGJOR EVENTS AND TIlilflG Ifi EVEfiT OF CORE l'.ELTDOWN Event 1

- Sprays and Coolers Operative Time =0 Flow stops, core and water start heat-up Time =100 min Cor'e' starts to uncover Time =150 min Core begins to melt Time =200 min Molten core is in lower head of reactor vessel, pressure is 2500 psia Time =210 min Reactor vessel fails, containment pressure goes to 25 psia Time =210 min Hydrogen burns, containment pressure goes to 67 psia Steam explosion possibility - minor consequence CONiAINMENT SURVIVES (Failure assumed 130 psia)

),

Time =10 bcurs Molten core has melted about 1 meter into basemat Tire = days Major problem - ha'dle hydrogen, oxygen - maintain contain-ment integrity g

I CAUTION:

- Keep sprays running

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- Keep water many feet over molten debris

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- WITHOUT RECOMBINERS Hydrogen cant nues to build up i

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EASEf%T SURVIVES Event 1

Conclusion:

This event should not p oduce m2jor releases b

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Event 2

- Sprays and Coolers Failed Before Flow Stops V1 Time =0 to Time =210 min Saue as Event 1 - containment pressure is 25 psia l'

Time =810 min Containment pressure is 70 psia Time =1 day

. Containment fails due to steam (mostly) overpressure -

about 135 psia r

CONTAINMENT FAILS e

Event 2

Conclusion:

This event leads to major releases.

I p.

10 l8l 323

The event tree for cnre melt leading to various releases is she,in in Figure 1.b.

The following are essential in the event of core melt.

1.

Sprays and coolers are required to prevent major releases.

2.

Hydrogen must be recombined or otherwise removed frcm containment.

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Larce Leak in Auxiliary __Buildin_g (AB) c.

The activity level in the reactcr coolant is so high that substantial releases can come from small amounts spilled in the AB which requires once through ventilation.

A leak of 5 gpn to the AB atmosphera is assumed for the expected level of leakage.

A leak of 50 gpm is taken as a large leak to consider a major leak in purp shaft sealing or some similar mishap.

Based on the leakage experienced already only the noble gases and no iodine are assured to evolve.

b i

The AB ventilation exhaust is assumed to flow through the charcoal rFi filters.

O C

d.

Hydrogen Explosion in Reactor Pressure Vessel

(_

A detonation of the hydrogen oxygen bubble in the reactor vessel could rupture the vessel and/or crush the core.

Rough analysis indicates that the pressure vessel would not rupture.

Postulation

+

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of the core response is difficult.

If the core is crushed, it could effectively prevent core cooling leading directly to the core melt r - -

sequence described earlier.

It is unlikely that compr.ssion s;ould f

lead to criticality.

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This table includes a number of assumptions about activity and weather.

These assumptions have been chosen conservatively.

In an actual release, the release. ate ar..' seather should l'e evaluated as they are at the time, and the decision based o-tose values.

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WORXSHEET PARE 1 EXPECTED PLATJT RELEASE i

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RESPONSE (RAtlGE?)

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DECIDES EVENT l

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i Loss of Reactor Restore Flow Within 1 hr.

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Coolant Pump I

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l flow within 1 hr; Leak Rate I is X/Q x 10 recirculate tSrough I Evac children and Aux Bldg via RHR or pregnant women out to 2 mi.

HPl General evac.

out to 1 mi.

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b. Large Leak Cose in Rem /hr is X/Q x 104 l

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WORKSHEET PAGE 3_

EVACUATION l

WARNING WHO I

i EXPECTED PLANT RELEASE e

EVENT l

RESPONSE _(RANGE?_)

AND TI"E l

SCENARIO TIME DECIDES

[

Hydrogen No significant change No significant l Explosion in reactor or primary change unless l

l l

inside Reactor system other fcilures l i

Vessel resul t l

l 1

i l

Core crushed See " core melt" l

(unlikely) l i

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WORKSHEET PAGE 4 EXPECTED PLANT RELEASE I

EVACUATION i

WARNING WHO l

EVENT RESPONSE (RANGE?)

AND Tl?iE l

SCErdRIO l

TIf1E DECIDES e

i i

i Loss of Offsite Causes Loss of reactor l

Power coolant pump - see l

l sheet 1 l

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t WORKSliEET PAGE 6

i EXPECTED PLANT RELEASE I

EVAEUATION l

WARhlNG l

Wii0 i

EVENT RESPONSE (RANGE?)

AND TIME l

SCENARIO f

tit 1E t

DECIDES i

+

i Run out of Waste Release at rate of General Evac out ! l'ing (known l

Gas and other I 60 - 100 Ci/sec (if to 1 - 2 mi.

I capacity)

I l return line to coiitain-(poor met., less I

storage capacity mentisnotinstalled)l if cloud is l

I i

Ielevated) 1 i

i I

l

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i

{

If return line is No releace None l

installed l

I i

t I

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f

("I L4 VJ i

o e

APPENDIX 1 MAJOR SEQUENCES OF EVENTS fiajor sequences evaluated here ure tied to the loss of forced circu-lation in the RCS.

The loss of flow from the reactor coolant pump (RCP) is the generalized initiating event from which other initiating events such as loss of offsite power can develop.

APPENDIX 1.a SEQUENCES OF POSSIBLE SYSTEMS FAILURES i

f.

K Figure 1.b-1 shows the loss of RCP event tree.

This tree shows the k

various options available given the loss of the RCP, and indicates which b

combinations ef events or failures would lead to core meltdown (CM).

Ef if The sequences denoted with an asterisk are those which would be ex-k, pected to follow the core neltdown progression discussed below, leading P

l to the variety of atmospheric radioactive releases and consequences r

discussed later.

Some core meltdowns could be expected to be delayed

?

{

for roughly a week because of the availability of ECC injection over E

that period.

This method of core cooling, however, is not expected to k

be adequate to prevent core melt: as such a core meltdown is assessed v

[

to occur at roughly a week. A rough measure of relative probabilities c:-

of the various outcomes is indicated by the notation of L, 'i, H (low, p

j medium,high).

The column on the right-hand side of the rage indicates the relative probabilities of the sequences, with "LM" as the highest 3

probability and L M as the lowest.

Ir 181 334 x

r I

L

APPENDIX 1.b MAJOR EVENTS AND TIi11NG IN EVENT OF CORE liELTDOWN Event 1

- Sprays and Coolers Operative Time =0 Flow stops, core and water start heat-up Time =lDO min Core starts to uncover Time =150 min Core begins to melt Time =200 min Molten core is in lower head of reactor vessel, pressure is 2500 psia Time =210 min Reactor vessel fails, containment pressure goes to 25 psia Time =210 min Hydrogen burns, containment pressure goes to 67 psia v

Steam explosion possibility - minor consequence t

CONTAINMENT SURVIVES (Failure assumed 130 psia)

Time =10 hours Molten core has melted about 1 meter into basemat Time = days Major problem - handle hydrogen, oxygen - maintain contain-g ment integrity

(

CAUTION:

- Keep sprays running L

- Keep water many feet over rolten debris

- WITHOUT RECOMBINERS Hydrogen continues to build up BASEMAT SURVIVES p

(,

Event 1

Conclusion:

This event should not produce major releases i4 E

Event 2

- Sprays and Coolers Failed Before Flow Stops b

Time =0 to Time =210 min Same as Event 1 - containment pressure is 25 psia

[_

Time =810 min Containment pressure is 70 psia E

Time =1 day Containment fails due to steam (mostly) overpressure -

about 135 psia CONTAIN".ENT FAILS Event 2

Conclusion:

This event leads to major releases.

I P

?

181 335 4

The event tree for core melt leading to various releases is shown in Figure 1.b.

The following are essential in the event of cure melt.

1.

Sprays and coolers are required to prevent major releases.

2.

Hydrogen must be recombined or otherwisa removed from containment.

\\

=

f a

L b

t-F.

N i

L I

w8 P

b t

V i.

181 336

Ic.

Larae Leak in Auxiliary _ Building (AB)

The activity level in the reactor coolant is so high that substantial releases can come from small amounts spilled in the AB which requires once through ventilation. A leak of 5 gpm to the AB atmosphere is

[

assumed for the expected l' vel of leakage. A leak of 50 gpm is taken as a large leak to consider a major leak in pump shaft sealing or some similar mishap.

Based on the leakage experienced already only the noble gases and no iodine are assumed to evolve.

J k'

The AB ventilation exhaust is assumed to flow through the charcoal p

l; fil ers.

s Id.

Hydrogen _ Explosion in Reactor Pressure Vessel

(,.,

A detonation of the hydrogen oxygen bubble in the reactor vessel b

could rupture the vessel and/or crush the core.

Rough analysis indicates that the pressure vessel would not rupture.

Postulation d', '

of the core response is difficult.

If the core is crushed, it could effectively prevent core cooling leading directly to the core melt i

sequence described earlier.

It is unlikely that compression would f~

lead to criticality.

c r:.

W t

F 181 337 t

APPENDIX 2 Based on 1004 release cf Xe-133 in core into primary coolant; this is conservative, since some Xe will appear in the containment atmopshere instead of the primary coolant.

i.

Ye-I

,.t m,

r..

L,;.,

t f

4 -

(

L r._

E i-i I

I'

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181 338

a 5.

Some Considerations Regarding Decision Line 5.1 Wait af ter a transient or _ perturbation Present calculations (8 an, 4/1/79) show decay heat of about 6MW.

Therefore, it would take about 100 minutes to JnCoVer the core starting from a level about 6 feet above it.

Thus, t

time can be taken to reestablish forced reactor coolant flew,

(

or to assess the effects of a detonation in the RPV bubble.

h 5.2 P_repar_e the Auxiliary Building for unatten_ded g eration

{-

At present, the AB has fields in the 1 R/hr range due to i.

spills.

Based on the 3/31/79 RCS sample, the radiation field t

l' In the AB could rise over 1000 R/hr with reactor coolant ficw e.

L

['

in the decay heat circuits.

Once that flow is established the l

field will be high.

Estimates indicate that the vital elec-E

!au.

trical equipment in the AB can tolerate the high radiction L

field for many months even though much data is lacking.

i,?

E 5.3 Set up flow paths setting procedures in advance The present conditions can lead to nany situations where lack of e-(

a water path into or out of the RCS is needed, al-though a substantial period of time (about 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months ) would likely l

to be available to set up a path.

r I-e 181 339 i

APPENDIX 6 In view of the forecast over April 1-3, we used F-1 m/sec for the assumed weather.

The resul+

are theref

.servative.

The measured r

dosc rates and actual weat!.2r should be evaluated in making the actual decis4ons.

i t

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3-c 181 340

6.

Weather The table is based on F stability and 1 m/sec wind speed, in view of the April i-3 forecast.

At the approach to decision time for

(

evacuation, the appropriate met condition will be factored into i

the dose equations to determine the evacuation time, sectors, and i

distances for the evacuation.

h' >

E NRC is predicting X/Q for current meteorology as the incident progresses.

.o '

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5

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Dt\\

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5:25 a.m.

7.

Action Guidelines a.

Notify evacuation authorities two hours in advance to standby for a possible evacuation.

b.

Predicted doses of IR whole body or 5R thyroid in 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months -

mandatory evacua o.un of children ar 4 pregnant women.

c.

Predicted ooses of SR whole body or 25R thyroid in 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months -

mandatory evacuation of all persons.

I f:I Assumes general warning already that some form of evacuation t.

U may becorre necessary.

P 7

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101 749 IOI J 't c k

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OPERABLE /AVAILABLE STATUS 1.

"A" Reactor Coolant Pump running, all three others are considered operable.

2.

All Pressurizer Heaters operable.

3.

Pressurizer Spray operable.

4.

Both Decay Heat Removal Pumps and their attandant valves are operable.

5.

Both Containment Spray Pumps operable.

6.

Four Containment Far Coil Units operating, the other Unit is available.

7.

Two Nuclear Service Water Pumps operating, the other two are available.

S 8.

Two Nuclear Services Closed Cooling Water Pumps are operating, the other is available.

9.

Both Electric Auxiliary Feedwater Pumps are available.

10. Borated Water Storage Tank volume 200,000 gallons.

11. Both Emergency Diesel Units operable.

12. One Hydrogen Recombiner operable, the other is being tested 4

(0400 hours0.00463 days 0.111 hours 6.613757e-4 weeks 1.522e-4 months , 4/1/79).

I

13. Spent Fuel Pool in Unit i empty, Unit 2 status unavailable.

e

14. Two Sources of off-site power available.

15. Decay Heat Closed Cooling Water Pumps - both operable.

lOl 343

s e

DHR OPTION I - SUMP RECIRCULATION A.

General 1.

Trains totally split (DHR) 2.

Suction fron containment sump 3.

Cross-ct.nect to HPSI 4.

Makeup pumps (HPSI) split 5.

Either train is isolalle (from control room) if leakag.-

h-develops r

6.

All equipment is seismically qualified and part of ECCS y

7.

LPSI discharges to reactor vessel 8.

HPSI discharges to RCS cold legs t

t B.

DHR Alignment l.

Containment sump suction valves open (CR) t l'

2.

Suction cross-connects shut (2 local, 2 CR)

(

3.

Suction strainers?

4.

Pump seals to floor drain p

5.

Pumps can receive power from EDG (3000 gpm at 370 psig) 6.

DHR coaltes (require NSCCW) c.

7.

Outlet cross-connects closed (CR)

L 8.

Discharge can be throttled from control room 9.

Cross-connect with HPSI - one from each header (CR) s

10. Outside containment isolation valve (normally open - CR)

E

11. Injection into vessel r

L f

nj

~ td j

Oi

$2 b

- - - C.

HPSI (Makeup Pumps) (250 gpm at 2600 psig) 1.

Suction cross-connects shut (local) 2.

Pumps lA and 1C available 3.

Discharge cross-connects shut (local) 4.

Containment isolation valves open (1 valve in each of 4 injection lines - operatec from control room - normally shut)

{r 5.

Injects into 4 cold legs i

ff D.

Advantages 1.

Two independent trains (100% capacity) 2.

All components ECCS qualified 3.

After initial alignment - all equipment can be operated remotely 4.

Can be initiated at any RCS pressure s

E.

Disadvantages l.

Potential releases a.

Equipment is in auxiliary building 94 I

b.

Pump seal leakage L

E c.

Valve packing leaks d.

Possible relief valve actuation L

2.

To ensure circulation a path from the RCS to containment must t

be estabiished a.

Electromatic relief

[

b.

Code safeties E

c.

RCP seal failure

{

7 d.

Sample lines

)n Relatively dirty sump water is circulated through reacto9.j

,9 t

345 1

3.

L

DHR OPTION II - HOT LEG RECIRCULATION (NORMAL DHR SUCTION)

A.

Gene al 1.

Suction from hot leg 2.

Cross-connect to FPSI 3.

To make both trains operable - the trains will have to be cross-connected 4.

LPSI discharges to vessel 5.

HPSI discherges to RCS cold legs (system use is optional)

)

B.

DHR Alignment 1.

Hot leg suction from loop B a.

Possibility of existing steam or gas bubble in hot leg which would gas bind suction b.

Valves not desicned to operate after a LOCA 2.

Open parallel suction header valves a.

Operated from control room

'h b.

Inside containment c.

Pressure interlocked about 400 psig

-4 L

3.

Open single series valve inside containment (CR)

[

4.

Open single series valve outside containment (CR)

[

5.

Single line ties to both DHR suction lines thrcugh remotely

{

operated valves

[

a.

Valves are in auxiliary building b.

Not ECCS designed (lower reliability) c.

Both DHR trains cannot be used if the trains are isolated I.

from each other.

t Y

6.

Manual suction cross-connects shut (2)

I 346

'~'

. B.

DHR Alignment (continued) 7.

If the trains are operated cross-connected, a.

passive failure could disable both trains b.

the valves required to operate to split the trains may not be designed to operate in the radiation fields present l

8.

Pumps can receive power from EDG (3000 gpm at 370 psig) h 9.

DHR coolers (require NSCCW)

(

I Outlet cros9 connects can be operated from control room l

s

10. Discharge can be throttled from control room k,

11. Cicss-connect with HPSI - one from each header (CR)

12. Outside containment isolation valve (normally oper. - CR) b

(( ^-

13. Injection into vessel l'

e-9 f-C.

HPSI (flakeup Pumps - Use Optional) y[ (',

1.

Suction cross-connects should be shut a.

locally operated (manually)

[

b.

this decreases system flexibility but allows isoldiicn by remote operated valves on a passive failure a

0) 2.

Pumps lA and 1C available (250 gpm at 26]O psig)

'~

3.

sischarge cross-connects should be shut 'see 1 above) 4.

Containment isolation valves open (1 valve in each of H injection lines) -

a.

operated from cortrol room h

b.

norm.lly shut hy.

5.

HPSI is not required in this mode

!81 347

. D.

Advantages 1.

It is not necessary to establish a bleed path from the RCS to containment sump 2.

Sump water is not recirculated through the cores

?

3.

Pressures in DHR and iiPSI systems would *

.ower, thus reducing leakage b

4.

Flow rates would be higher than Option I 5.

HPSI is not r equired hi 6.

This is the basic alignment which will eventually be used when p

the refueling cavity is flooded after reactor vessel head removal g-t.

E.

Disadvantages I-1.

The valves in the hot leg suction line are not ECCS valves

}-

and may not operate when required 2.

This alignment requires low RCS pressure (about 400 psig) jc, a.

Bubble in core will expand and possibly uncover core p

T-b.

Long time period (hours) to depressurize i ~'

3.

Both trains cannot be used simultaneously and maintain train k

separation - there is no assurance that the remotely operated valves necessary to change from one train to another will operate 4.

A void may exist initially or may be established in the "B" hot leg thus gas binding the suction path and/or pumps.

This would disable the DHR system with no viable method of venting the gases from the suction.

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INTERIM ACTIONS ON OPERATING B&W PLANTS o VERIFY EMERGENCY FW VALVES OPEN INDICATIONS ALONG; USE Pp o

INTRANSIENTS, D0 fl0T RELY ON PL o

IF HPI ACTIVATES, DO NOT TURN OFF UNTIL:

A.

2 LPI ARE ON, OR B.

HPI OPERATES 20 MINUTES, AND T AND T ARE 50 BELOW T c

g SAT IF HPI ACTIVATES, AND RCPs ARE ON, AT LEAST ONE RCP PER LOOP SHOULD BE MAINTAINED o

IF ECCS ACTIVATES, ISOLATE CONTAINMENT L4 LTl N

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ML19224B024

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