ML20099A287

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Forwards PRA Input to ITAAC Section 19.8 Re Tier 1 Treatment of Design Features Identified as Important by PRA
ML20099A287
Person / Time
Site: 05200001
Issue date: 06/30/1992
From: Duncan J
GENERAL ELECTRIC CO.
To: Kelly G
NRC
Shared Package
ML20099A263 List:
References
NUDOCS 9207290085
Download: ML20099A287 (11)
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Text

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19.8 Tier 1 Treatment of Design Featwes Idesb5ed as Imaportant by the FRA As the PRA was being finalized during NRC staff development of the Final Safety :

Etraluation Report, the PRA was reviewed to identify the most important PRA related

'ABWR features. Thejudgement of several engineers was used to identify those features -

and capabilities which are most important in maintaining a low core damage frequency _

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and in mitigating the conseq.nences of an accident should one occur, Achlesing both of.

these objectives results in a balanced design in that many very diverse features provide.

. defense in depth to avoid excessive offsite consequences.

j The results of this review are summarir.ed in Table 19.8-1 through 6.- For each-8" feature, reference is provided to the corresponding verifying ITAAC byindicating the system number followed by the enny number in the corresponding ITAAC table. In -

addition, key subsections of Chipter 19 are identified to allow a reviewer to appreciate the general significance of the feature beyond that identified here, j

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e Table 19.8-1 FRA INPUT TO ITAAC: PREVENTION OF CORE DAMAGE Chapter 19 General capability -

_ Specific Feature / Capability Subsection.

ITAAC Reference f

Redundant Systems

  • *Ihree separated divisions of.

19.1.2 2.4.l(RHR) - 1,2,3. 8,9.18 j

ECCS and decay heat removal, 19.65 2.4.2(HPCF) - 1,2, 3,4,11,10 ECCS pumps able to pump 19D.5.11.3 saturated water.

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  • RHRvesselinjection valve which 19J.3 2.4.1 - (RHR) -7

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admits the water to 'the RPV and 2

drywell spray valve have i

handwheels forlocal manual operation without power..

1

  • Automatic depressurization for 19.1.2 2.1.2 (Nuclear Boiler)-11.12 transients and LOCAs 19D.6.2.5 Diversity
  • RGC capable of operadon for -

19.1.2, 2.4.4(RCIC) - 6 says L=oladon fails as is several houn without AC power, 19E.2.2.3 on loss of ac. Need to add switchover.

and ability to override switchover 19D.4.2.8

(

Current Power supply) -

to makeup water source from.

19D.4.2.9 CST to suppression pool.

  • Combustion Turbine Generator, 19D-2.12.11 (CrG) - 1 connectable to atleast one of three safety divisions to provide ac power.
  • Ability to operate one HPCF 19D 2.2.6 (RSS) - 1 t

pump independent of essential.

multip'exing system.

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8 Tame 19.8-1 PRA INPUT TO ITAAC: PREVENTION OF CORE DAMAGE (Continued)

Chapter 19 General Capability Specific Feature / Capability Subsection ITAAC Reference g

Diversity

  • Seismically qualified ac 19.1.2 2A.1(RHR) - 7 Y:

independentwater addition 2.15.6 (FPWSS) - 13 (Flow rates will be sptem, including dedicated add d) diverse diesel (which need not be y

seismically qualified) and E

manually operable valves.

E Calculated flow rates:

W

- for vessel injection, between 0.50 t,.

and 0.60 cubic meters /sec with RPV at ambient pressure. The shutoff head for RPVinjection should be 1.7 MPa.

- for drywcII spray, between 0.50 and 0.60 cubic meters /sec with drywell at ambient presure.

Support Sprems

  • SufIicient cooling capacity 19D.6A.2
  • 2.11.9 (RSW) - (to be added) Heat available in service water systems removal capadty will be compared with to provide seal and motor heat remon) requirements by bearing cooling for ECCS core enluation of 23-built components.

cooling pumps with one RCW and one RSW pumpin each loop fn each division and two RCW beat exchangers in exb division operating.

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Table 19.81 PRA INPUT TO TrAAC: PREVENTION OF CORE DAMAGE (Continued)

Chapter 19 General Capability SpeciGc Feature / Capability Subsection ITAAC Reference

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Support Systems

  • Sullicient cooling capacity 19D.6.4.2 2.11.9 (RSW) - (to be added) Heat available in service water systems removal capacity will be compared with supporting each RHR division to beat removal reqmrements by remove heat from the RHR heat evaluation of 2& built components.

g exchangers during IJOCA with all pumps and beat exchangers in thatdivision operating.

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Minimize Potential for

  • Highly reliable reactor protection 19.3.I.3 2.2.7 (RPS) - 2,4,5

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Failure to Shutdown

'and control rod drive system to 19D.6.5.2 2.2.2 (CRD) -2,3,4,9,10 I

insert control rods.

19D.6.5.6

  • Altemate rod insertion system to

' 19D.6.5.6 No ARI ITAAC yet provide backup and diversity to

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control rod drive system.

  • Automaticallyinitiated standby 19.3.1.3 2.2.4 (SLC) - 1, 2, 3, 4, 5, 6 liquid control system to provide 19D.6.5.4 backup shutdown capability in event of failure to insert control rods.

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Table 19.8-2 PRA INPLTr TO ITAAC: AVOIDANCE OF SUPPRESSION POOL BYPASS Chapter 19 General Capability Specific Feature / Capability Subsection ITAAC Reference

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Avcid Unisolatable RWCU

  • Reactor water clean-up Isolation 19.3.2.6 2.6.1(RWCU) ~ 3. In addition, see Break

. Valves must be properly quah6cd RWCU EQcotryin Table 3.0 ofter 1 (including seismic) for expected material.

duty

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  • Reactor water cicanup drain line 19.3.2.6 2.6.1 (RWCU)-not addre xd yet.

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includes globe vahe which can be closed by remote manual means.

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Control Unisolatable

  • Reactor water clean-up suction 19.3.2.6 2.6.1 (RWCU)-4 to be added.

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2 RWCU Break nozzle must be atleast 5 feet above the planned e!cvation of the top of the active fuel.

Control Unisolatable -

RWCU Break tie in to the suction line must be-at Icast 18 inches above the planned elevation of the top of the active fuel.

Avoid Unisolatable RHR

  • Seismically. qualified RHR 19.6.3'

.See RHR EQcntryin Table 3.0 of Breal

- isolation pool suction valve

' Tier I material Release Paths to

  • Atleast 4 SRVs operate in ADS 19E.2.3.3 2.1.2 (Nuclear Boiler)- 11 Suppression Pool -

mode.

  • At least ten 24" upper vent paths 19E.2.3.3 2.14.3 (RPV Pedestal) - Mgure 2.14.3

- from the drywell.

shows ten 27" vents. Need to reDect in table.

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. Table 19.8-2 PRAINPUT TO ITAAC: AVOIDANCE OF SUPPRESSION POOL BYPASS (Comairmoed) 4 i

Chapter 19 l

General Capability Specific Feature / Capability Subecction -

ITAAC Reference 7

  • At least 20 ft Suppression pool 19E.2.3.3 '

2.14.3 (RPV Pedestal)-Fqpzre 2.1.4.2a k

shows elevation of quencher. Fqpare l

level above the SRV discharge.

l 2.14.3a clevation of the bottom vent is sufficient so verify. However, need to~

g, reacct in tabic.

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  • At least 15 ft Suppression pool 19E.2.3.3 2.14.3 (RPV Pedestal) - Figure i

2.14.3a is inconsistent with item 3. 'Ihe E

level above the DW vent.

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figure shows about 12 feet '

submergence.

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Valve Reliability

  • Main Steamline Druins are dosed 19E.2.3.3 2.1.2 (Nuclear Boiler) - ?

during norrnal operation.

Figure 2.1.2b shows the valves as nonnallyopen. Isolation addressedin section 2.4.3 text.

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  • Drywell equipment and floor 19E.2.3.3 No ITAAC yet to cover this.

drain sump discharge lines contain containmentisolation valves and check vahes to prevent backflow to other areas.

Valve Controls

  • ECCS valves have a remote '

19E.2.3.3 Need ECCS ITAAC.

ual closure capability.

m Minimize Leakage

. Leakage from equipment to -

19E.2.3.3 2.I1.3 (RBCWS)-Not currently addressed.

.. losed cooling water systems is c

highly restricted.

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Table 19.8-3 PRAIN"UTTO ITAAC: MAINTENANCE OF CONTAINMENTI t

NTEGRITY E.

i Gener21 Capability l

Avoid Hydroga: Related Specific Feature / Capability Chapter 19 Subsection i

Threats

  • Provisions to provide inerted ITAAC Reference containment 19.6.6 Avoid Containment 19.6.8 2.14.6 (ACS)-I Structural Failure
  • Containmentovcrpressure h

19.2.4.3 protection system with rupture

, 2.14.6 (ACS)-5,-6,-8 disk set-point established at 90 psig and nominalflow rate of

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35 kg/sec when containment E

pressure is 90 psig.

E Minimize Challenge to

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  • Pasivu Flooder system:

'E

- Ten va}ves which open when No ITAAC section yet.

g lower drywell temperature 2

exceeds 5007

- 10.5 liters /sec nominal flow rate Per valve

! Maintenance of i

Suppression PoolIntcgiity; RHR heat exchangerseismic j

capcity 19J.3 See RHR EQ entry in Table 3.0 of Tier 1 material j

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E Table 19.84 PRA INPUT TO ITAAC: MAINTENANCE OF CONTAINMENT IN'IEGRITY

,e Chapter 19 i

General Capability :

Specific Feature / Capability Subsection ITAAC Reference n

i Provisions to provide inerted 19.6.6 2.14.6 (ACS)- 1

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I Avoid Hydrogen Related Threats containment 19.6.8 l

Containment over pressure 19.2.4.3 2.14.6 (ACS) -5,--6. -8 Avoid Containment Structural Failure protection system with rupture 5

disk set-point establiabed at E

l l ' 90 psig and nominal flow rate of E

l 35 kg/sec when conrainment pressure is 90 psig.

2 Passee Flooder system:

No ITAAC section yet_

Minimize Challenge to o

Containment

- Ten vahes which open when lower dryvell temperature exceeds 500'F

- 10.5 hters/sec nominal flow rate Per

  • RHR heat exchanger seismic 19J3 See RHR EQcntry in Tabic.9 3 of Maintenance of rier I material Suppression PoolIntegdty capacity 1

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6

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Table 19.84 PRAINPirrTO ITAAC: MINLMrfETHRENIS FROM INTERNAL FLOODS Chapter 19 i

General Capability Specific Feature / Capability Subsection ITAAC Reference

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Defense AgainstTurbine

  • Normally closed watertight door 19R.4.3 2.15.11 (Turbine Building) - 5 5

Building Flooding between turbine building and 3

service building tunnel.

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Defense Against Controi

  • Control building lower floor level 19R.4.4 2.15.12 (Control Building) -2 l;

l Building Flooding sensors which alann at 0.15 meter E

and trip RSW pumps and close g

RSWisobtion valves in affected i

division at 0.8 meter.

  • RSW pipe run between control 19R.4.4 2.15.12 (Control Building) - 2 building and fint RSW valve outside control building is limited to less than 2000 meters length.

Defense Against Reactor

  • ECCS rooras bave water tight 19R_4.5 2.15.10 (Reactor Building)-2 Building Flooding doors which open into conidor.
  • Reactor building corridor and 19R.4.5

' 2.15.10 (Reactor Building) - 2 ECCS rooms (Floor B3F)can each contain largest flood source (i.e.,

equilibrium level with suppression pool is lower than room ceiling).

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  • Reactor building floor B1F 19R.45 2.15.10 (Reactor Duihling) - 2 outside secondary containment sumps have overfill lines to B3F corridor.

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'8 Tame 19.8-5 FRAINFUTTO TTAAC: MINIMIZETHREATS FROMINTERNALFIRES I

Chapter 19 General Capability Specific Feature / Capability Subsection ITAAC Reference

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Remote RCIC Operation

  • Capab;1ity to operate RCIC from 19M.4.1.1

' 2.4.4 (RCIC)- 11 (needs to be added) y outside the control room, 19M.3,

Testing willverify operational 19M.6.2 -

capability?

N Depresurization

  • Capability to operase four SRVs 19M.S _

2.2.6 (RSS) - 1. Ncci to spccify four.

from the remote shutdown panel.

19M.6.2

E c-L Divisional Separation 4 Three hour rased fire baniers 19M.2 2.15.6 yr5) -15. + addition ace &d

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c surrounding each fire area which 19M.4.1.1 verify byinwc&,s of as built plant

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includesindividual safety.

that safety divisions s c isolaud from

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divisions.: Includes barriers each other by three hwr rated firr

.T barriers.

formed by 1) concrete fire barrier floon, ceilings, and walls-

- 2) partitions; 3) rated fire' doors;

4) penetradon seals for process

- pipes and cabic toys;5) special assemblies and constructions; and

6) fire d2mpers y

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<x 1 Table 19.84 c.

FRAINPUTTO ITAAC: MINIMIZETHRFEISWInf R SHUTDOWN

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Chapact 19 -

Specific Feature / Capability

Subsection ITAAC Reference C

General Capability Decay HeatRemoval:

  • - No isolation of SDC on loss of 19Q.11_

2.4.1 (RHR)- 12

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f RPSlogic power 19QC I

Decay Heat Removal and

  • l3 ECCS divisions with support 19Q.7 2.4.1 (RHR) g i

Inwntory Control

' systems physically separated and 2.4.2 (MPCF) - 1 m

independent -

Ei P'

y Inventory Control

  • RPVisolation on low water level 19Q.4.2 2.4.1 (RHR) - 12

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  • RHR mode switch automatically 19Q.4.1 :-

2.4.1 (RHR) g;

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realigns system'.

19Q.4.2 4.

  • AC independent water addition L IfQ.4.2 2.4.1.(RHR) - 7 _

system I

  • : SDC piping connects to norrie in 19Q.4.2 2.1.1 (Rwtor Pressure Vessel.

i -

' RPV atx:ve top ofactive fuel '

System)'- 1 j '

Electric Power Availability.

  • 2 offsite power and 4 onsite 19Q.4.4 -

2.12.1 (Electrical Power Distribution -

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powersourcesavailable.

System) - 1

< physically separated and ~

2.12.11 (Combustion Turbine '

T independent Generator) -l '

2.12.13 (Emergency Diesel Generator System) - 1,3 -

iN Flood Control '

+ iWatertight doors and Door drains 19Q.6, 2.15.10 (Reactor Building) - 2 2.15.12 (Control Building)'- 2

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t 2.15.11 (Turbine Building) -5 '

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