State-of-the-Art Reactor Consequence Analyses, Office of ...
103
1 4 a. OF CIý A ýSE ýNL Y - ýP deci oýn al I ý ma t ion U.S.NRC UNITED STATES NUCLEAR REGULATORY COMMISSION Protecting People and the Environment STATE-OF-THE-ART REACTOR CONSEQUENCE ANALYSES Office of Nuclear Regulatory Research Advisory Committee on Reactor Safeguards Briefing November 16, 2007 /FFIGFIL sE Y- Pr deic onal = ation 1
Transcript of State-of-the-Art Reactor Consequence Analyses, Office of ...
1 4 a.
OF CIý A ýSE ýNL Y - ýP deci oýn al I ý ma t ion
U.S.NRCUNITED STATES NUCLEAR REGULATORY COMMISSION
Protecting People and the Environment
STATE-OF-THE-ART REACTORCONSEQUENCE ANALYSES
Office of Nuclear Regulatory ResearchAdvisory Committee on Reactor Safeguards Briefing
November 16, 2007
/FFIGFIL sE Y-Pr deic onal = ation
1
Agenda
" Overview• Process Review" Preliminary Results of the Peach Bottom Atomic
Power Station and Surry Power Station Assessments
- Preliminary Findings- Sensitivity Analyses- Emergency Preparedness-- Comparison with the 1982 Sandia Siting Study
* Commission Paper on Reporting Latent CancerFatalities
• Path Forward
FICI SE LY-
f#f, ionP ede' ' in I mfo
V 0 0
JFF /AýL E Oý - decil 'om
SOARCA Objectives
* Perform a state-of-the-art, realistic evaluation ofsevere accident progression, radiological releasesand offsite consequences for dominant accidentsequences
* Provide a more accurate assessment of potentialoffsite consequences to replace previousconsequence analyses
_ffICIAL ýS ONLY-ýredl•al Info, on
1 6 0
Id L US ON Y- re ecisi I Inform
Severe Accident Improvements
• 25 years of national and international research
* Regulatory improvements reduced the likelihood ofsevere accidents
• Improved modeling capability
* Improvements in plant design
Other plant improvements
P 1ci SoE,n LYP r•,e/dec'i'o n~a forn•I
4
ýFýFlIAL U Oý ý P- eciisio ~aal Infforur fmi
SOARCA OVERVIEW
SOARCA PROCESS
RESULTS
,AFICIA US ON-Pre cci 'onal In ation
5
SOARCA Approach° Full power operation° Plant-specific sequences with a CDF>10-6 (CDF>10-7 for bypass
events)" External events included• Consideration of all mitigative measures, including B.5.b" Sensitivity analyses to assess the effectiveness of different safety
measures• State-of-the-art accident progression modeling based on 25 years of
research to provide a best-estimate for-accident progression,containment performance, time of release and fission productbehavior
" More realistic offsite dispersion modeling• Site-specific evaluation of public evacuation based on updated
Emergency Plans6 Dose threshold for reporting. latent cancer fatalities (5 rem in one
year, 10 rem lifetime)
9iAFiO 0IY~ 6edecisio al Io %on
0
SOARCA Insights
° Sequences dominated by external events, primarilylarge seismic events (PWR also includes bypassevents)
* Previously used sequences have a significantly lowerprobability of occurrence or are not consider to befeasible
- Alpha mode failure- High pressure melt through- ATWS
° B.5.b measures are effective at preventing coredamage and containment failure
OFICIAL E ON -7
r4ed cisio al In ati~oni\ ,,
SOARCA Preliminary Findings
" All events identified by the screening criteria (including bypassevents) would be mitigated by B.5.b measures or, in some cases,by other plant systems
° Analyses were performed which -confirmed effectiveness ofmitigative measures
* Performed sensitivity analyses assuming no mitigative measuresto further demonstrate the effectiveness of these mitigativemeasures and to provide results to compare with 1982 SNL. SitingStudy
" The analyses performed with and without mitigative measuresresulted in significantly less severe consequences than the 1982study
kOFICIA SE ON 8re csi nal for ation
PFI ML U ON dci" or "n
Sequence Screening Process(Internal Events)
Initial Screening - use enhanced SPAR models to screen out lowCDFs initiating events with an overall CDF <1.OE-7 and sequenceswith a CDF <1.OE-8. This step eliminates <10% of the overall CDF(typically about 5%)
* Sequence Evaluation - identify and evaluate the dominant cutsetsfor the remaining sequences (-90% of initiator CDF). Determinesystem and equipment availability / unavailability and accidentsequence timing
Scenario Grouping - group sequences together that have similartimes to core damage and equipment unavailability
Sequences selected refined by external events and mitigativemeasures assessments
FICIA SE0o Y-ar e dl ' 6nal % f or ation
7 A NL U z ýed islo ~fo~rmat~i
Sequence Screening Process(External Events)
" Identify dominant externally initiated event sequences (e.g., fire,seismic, flooding, wind) based upon available probabilistic riskassessment documentation from NUREG-1 150, IPEEE submittals, aswell as any additional / available supporting documentation
" Seismic margin assessments were excluded from this effort becausethey do not provide the required risk information
" Identified potential mapping between dominant external events andinternally initiated events identified by the SPAR analysis
* Where mapping between external and internal events are not possibleor appropriate, a unique externally initiated event or sensitivity studywas recommended
° The resulting limited set of scenarios obtained for each SOARCA plantwas used for subsequent accident progression and consequenceanalysis
FFI USE NLY- 104ý'u "Lin
Containment Systems StatesIdentify the availability of engineered systems that canimpact post-core damage containment accidentprogression, containment failure and radionuclide release
Identify the anticipated availability of containment andcontainment support systems not considered in the Level 1 coredamage analysis:
- determine availability of front line system using cutset information- constructed a system dependency table showing the support
systems required for performance of the target front line systemdetermine availability of front line system using engineeringjudgment
Availability of systems such as low pressure injection that canimpact containment accident progression (e.g. cooling debris inreactor cavity or cooling reactor vessel after core damage butprior to vessel failure) that were not evaluated in the Level 1 coredamage analysis will be determined using engineering judgment
OFF USE LY 11P cisi orma ion ,
Mitigative Measures Analysis
o The mitigative measures analyses are qualitative,sequence-specific systems and operationalanalyses based on licensee identified mitigativemeasures from EOPs, SAMGs, and other severeaccident guidelines that are applicable to, anddetermined to be available during a sequencegroupings whose availability, capability and timingwill be utilized as an input into the MELCORanalyses
o FIC LUSEO LY- 12PAre e 'sion Info mn t' n
Mitigative Measures Analysis Process
" For those dominating sequences / sequence groupings within thescope of SOARCA, applicable mitigative measures that arepotentially available (not eliminated by initial conditions) areidentify
* The staff performs systems and operations analyses based onthe initial conditions and anticipated subsequent failures usingapplicable performance shaping factors to:
- verify the availability of the primary system,- determine the availability of support systems and equipment- determine conservative time estimates for implementation
• The staff determines the anticipated availability, capability and thetiming of implementation
* MELCOR will determine the effectiveness of those mitigativemeasures that are expected to be available at a given time
FICI LUSE Y 13re d ion In rmation
0
Emergency Preparedness
o Techniques used to model EP was previously presented to ACRS
• Effort was successful in developing cohort data
Population
Evacuation timingTravel speed
Roadway network
Data was used in MACCS2 to develop consequence estimates
Staff is considering assessing earthquake impact on EP throughsensitivity analyses
F1C USE NL - 14)r~e 'ion I rmatio
ICA S NL ecisi form .n
MACCS2 Assumptions
* .Cancer detectability threshold for latent cancer fatalities* No contaminated food or water consumed* Latest federal guidelines used for dose conversion factors• KI ingestion by half the 0 - 10 mile population, suboptimum timing" Median values from US/CEC study of uncertainty for non-site
specific parameter" Site-specific population and meteorology* Costs cost-of-living adjusted from NUREG-1 150* Projected dose during emergency period, 5 rem relocate in 1 day;
2 rem, 2 days* Return criteria: 0.5 rem in 1 yr for Peach Bottom, 4 rem in 5 yr for
Surry• In general,1-hr plume segments are used
6 FICA"E ONLa, 15Pre ec onal In'k t3io
0 FIC L U LY - Pre cis nal Infor io
Structural Analyses R 3 __
Objective Dw -WDrywell
Evaluating behavior of containmentstructures under severe accident Peach Bottom "Mark I-
conditions, and predicting the Steel Containment"
following performance criteria at theselected sites:
* Functional Failure Pressure - LeakageStructural Failure Pressure - Rupture
* Develop Leakage Rate and/or Leakage Areaas a Function of Internal Pressure
Surry "Reinforced ConcContainment"
,ONFICIAL USE ON Y- 16rede si n Infor a n
rete
h Bottom Mark I - Steel CPeacl ont.Approach:
Review/reevaluate major failure criteria based on 25 years ofresearch and testing performed by SNL and other organizations
Result:* The dominant cause for containment leakage is head flange bolt
strain undergradually increasing internal pressure
68 - 2-1/2"(P Bolts,/TYP A-320-L7
\. -"
F'CI EO0NNL y-"\Pred eelsion al Irtion
17
, FY- ecisi al I rma io.o. -
Peach Bottom Results
Pressure vs. Area of Leakage atPeach Bottom (Mark I) Containtment
140
120
100
Cu
80
60
40
20
0
-201 0 100 i
Area of: BotLeaag Ela6tcity(psig) (in2)~e,: : ,i•:,::,::
10 0.00 Elastic
15 0.00 Elastic
20 0.00 Elastic
25 0.00 Elastic
30 0.00 Elastic
40 0.00 Elastic, gasket
50 0.00 Elastic, gasket
60 0.00 Elastic, gasket
70 0.00 Elastic, gasket
80 0.00 Elastic, gasket
81 0.46 Elastic
82 1.20 Elastic
83 1.94 Elastic
84 2.68 Elastic
85 3.41 Elastic
90 7.10 Elastic
.0 -1i4.40 Wasuc
120 29.24 Elastic
5%Relaxationof pre-load
Pd= 56 psig
Pressure (psig)
FFIC L1 US .ONLY
41re e sio ,no ion18
OF IC L NLY decisi al frmati
Surry - Reinforced Concrete - Cont.
Approach:" Research of 25 years of analyses and testing on reinforced
concrete containments support the hypothesis of "leak-before-break" failure mode. Therefore, it is expected that the range ofpressure needed for catastrophic burst can never be reached --
leakage should prevent catastrophic burst.• General behavior of concrete containment under gradually
increasing internal pressure:
- First, cracking of containment concrete.- Second, yielding of liner then tearing, and path(s) for leakage is/are
created.- Third, yielding of hoop-reinforcement, and enlarging.- Finally, reinforced concrete containment structures are predicted to
have significant leakage once the global strain levels are reached onthe order of 1% to 2%.
•OFHCI SE ONO .- 19/ Pr e o na for ation
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?rI ý E0Pre c'onal I a"i
Evaluation of Reinforced ConcreteContainment Structures
Containment Radius Inside Rc (ft)
Containment Volume Vc (ft3)
Density p - N2 or air (#1ft3)
Atmospheric Pressure Pa (psia)
Liner Plate Thickness tL (inch)
% of Liner Plate pL = tL I tc
Diablo Salem Seabrook SurryCanyon
70.00 70.00 70.00 63.00
2.63E+06 2.62E+06 2.70E+06 1.80E+06
0.0752 0.0752 0.0752 0.0752
14.70 14.70 14.70 14.70
0.375 0.375 0.375 0.375
0.0089 0.0069 0.0069 0.0069
42.00 54.00 54.00 54.00
14.12 15.644 20.364 18.777
0.028 0.024 0.031 0.029
0.037 0.031 0.038 0.036
3.OOE+07 3.OOE+07 3.OOE+07 2.80E+0747.00 47.00 65.00 60.00
Containment Shell Wall Thick tc (inch)
Hoop Rebar Area Ar (in2lft)
% of Hoop Rebar PH = Ar / tc
% of Total Steel pT = PL + pH
Modulus of Elas. of Liner & Rebar (psi) I 3.OOE+07 I
Containment Design Pressure Pd (psig)
Liner Plate Yield Strength SyL (psi) II 5.00E+04 5.OOE+04 5.00E+04 5.OOE+04 3.20E+04
-Ribf-YI1Id-Siten--g1rftPSI) 7.00+ OOE+04 +04 j7.0E+04J - 7.OOE+04 J 5.OOE+04
Rebar Strength @ 2%StrainS 2% (psi) 7.50E+04 7.50E+04 I_7.50E+04 7.50E+04 5.40E+04
I %Fi1I US 9N Lkyre M ~sionNýfr~ato~~
20
SI LnUS 0 Y-CPrde sional f atio- Reinforced Concrete - Cont.Surry
Leak Rate as a Functionof Pressure Ratio for
SURRY400%
350% -. • , .. . "
c 300% -
250% ,, .
200%
S150%
u 100% -
50%
0%
0.0 1.0 P/Pd 2.0 3.0
SURRY
Pressure P/Pd LR(%Mass/Day)
P = Pd=60psig 1.00 0.14%
Liner@ Sy-L 1.37 10%
Rebar @ Sy-r 1.99 13%
2% Strain 2.13 62%
145 psig 2.42 352%
AFICI EQ0 Y-re ional In ation
21
Surry Resultsf Surry Containment Performance:
Leakage Area as a Function of Pressure Ratio Due to Average AirSonic Velocity of 1,258PYN, and for Temperature LeVels up to 3001F
at Pressure Resisting Members
I, Surry Containment Performancer:Leak Rate as a Function of Pressure Ratio
at Temperature Levels up to 300OF5
nr A
a)
-"t. ': • :
85.0 ~-4 - _ _ __ _ _
15.0
55.0
45.0
35.0
25.0
IM i
335%
310%
285%
260%
-235%7
e 210%
185%, 4tno,
P
Ila)a)
a)a,
-I
wlUU7 7 i.
135% -
'110%
850%
60%
3576
10% - t , -
/5.0V A•
-.-- ,DnV I -l~ = = fl == 9- 9 Nn*-t-- -Iv 1 19 - , ;..ýý..ý -I 1.1L., . -DU I.VU P/Pd LOU Z.VU Z. i
FICI U ON/Pre iona I In5 ation
22
SURR - Reinforced Concrete - Cont•/~-~.--
co
PredictedLocations of leakage
(at adjacent to geometrydiscontinuities) /
41 'PH .
7'-6" ,'
@EH... ... ... . .. . .-- -
Equipmentand/or
PersonnelHatches
61,001
..... ....
Plan View(NTS)
SURRY Cont. Ref. Dwg.:11448-FV-S1A11448-FV-iF11448-FM-IA11448-FM-IF11448-FV-IJ11448-FC-15G
EL
110'-O" IDElevation View
(NTS) ,-P ,-,^i.~ ~.
r4edec .*nal Info)1\ato
23
0
Peach Bottom Accident Sequences
PRA models indicate core damage probabilitydominated by seismic event, which is functionally along-term SBO (1 xi 0-6 to 5x10 61/yr)
- Fire and flood events would be similar in terms of coredamage progression
° Internal events have frequencies <1 0-6iyr
- Initially identified 1 sequence, Loss of Vital AC Bus E-12, as>10-6/yr; subsequently determined to be <10-6/yr
Notwithstanding, MELCOR analysis showed event to bemitigated without crediting B.5.b equipment
• Bypass events are of very low frequency: -10-1 0/yr
H0FCI "L SEQ ONY-- 24redbGl'onal lhdmation
• IAL NLY - r ecisiona ation
Peach Bottom LTSBOApproach to MELCOR Analysis
Perform MELCOR analysis crediting B.5.b equipmentand procedures
- Evaluate sufficiency of B.5.b measures to preventenvironmental release
- B.5.b measures were demonstrated to prevent core damagefor LTSBO
Perform MELCOR analysis without crediting B.5.bequipment and procedures- Understand value of mitigation strategies
ICALSONL - 25Zrede '=alt Inomatio~n
Peach Bottom LTSBO
" Loss of offsite and onsite AC power• RCIC starts automatically* Operator, by procedure, depressurizes at 1 hr" Batteries exhausted at 4 hours
° MitigatedPortable power supplyensures long-term DCto hold SRV open andprovide level indication(allows management ofRCIC)
• Unmitigated- After 4 hrs:
• Open SRV recloses
" RCIC terminates• No subsequent
actions taken
ICIAL rONared is' al In atfi
26
Peach Bottom LTSBO
B.5.b mitigation- Portable power supply for SRV operation and reactor
vessel level indication
" Prevent excessive cycles on SRV• Provide level indication to manage injection
- Manual control of RCIC without DC power- Portable diesel-driven pump (250 psi, 500 gpm) for makeup
- Portable air supply to operate containment vent valves
PflrICIAL S 0 27rede s al Information
0
Bottom LTSBO Pressure ResponsePeachSuccessful Mitigation with Portable Equipment1400
r."
I-
CL
CL
1200
1000
800
600
400
200
Operator manually4 opens 1 SRV
-Station battedportable powe.. .....t~o sust~ain_ ope4
RPV Pressure -----
es exhausted;r supply engagedn SRV
0 I I I I I I I
0 2 4 6 8 10 12 14 16 18 20 22 24
time [hrj
re ona =atiý28
(I1F'XLUS 0 Y-Pre cisL alUnfor
Peach Bottom LTSBO Level ResponseSuccessful Mitigation with Portable Equipment
700Operator manually
00 -~ opens 1 SRV600 ---------------- ............
4)
0In
II
500
400
Operator takes manualcontrol of RCIC Reactor Water Level
--- Steam LineNozzle
- Automatic RCIC actuation300
200
100 High Supp. Pool Temp --RCIC Isolation
0 Ia I I0I
0 2 4 6 8 10 12 14I
16 18 20 22 24
time (hr)oICIAL SE NLY
/Prede nal information29
Peach Bottom LTSBO Pressure ResponseSuccessful Mitigation with Portable Equipment
30
Drywell Pressure Operator opens =
25 ---------------------------------- containment vent - . -' - _
'- 20
15 i--------------------------- ------------(I)
CL 10 ---------------------------------Operator re-closes
containment vent5
0
0 2 4 6 8 10 12 14 16 18 20 22 24
time [hr]
FICIAL USE 0 -i re cnisna for ation30
OF CI L US 0 Y -Pr ec 'onal nfn
Peach Bottom LTSBOSuccessful Mitigation with Portable Equipment
• B.5.b equipment is sufficient to prevent core damage
- No source term- No offsite health consequences
-r Aa noEQ0 Y-red c2isi at In, mation
31
S
Peach Bottom Mitigative MeasuresSensitivity Analysis
* Long-term SBO - without B.5.b mitigation
- Loss of offsite and onsite AC power- RCIC starts automatically- Operator, by procedure, depressurizes at 1 hr- Batteries exhausted at 4 hrs
* Accident progression
- RCIC lost at 5 hrs- Core uncovery in 9 hrs- Core damage in 10 hrs- RPV and containment failure in 20 hrs, start of radioactive
release (liner melt-through)- Time from start of evacuation to radioactive release: -17 hrs
__qiOFFI L USE ^Y 32Rqecislo al jInf rma n
0
Peach Bottom LTSBO Pressure ResponseNo Mitigation with Portable Equipment
to
&-.A
I.-
1400
1200
1000
800
600
400
200
00 2 4 6 8 10 12 14 16 18 20 22 24
time [hr]
O FICIAL/SL ONY4ý-Pre Gi nal In ation
33
0 U L
Peach Bottom LTSBO Level ResponseNo Mitigation with Portable Equipment
800Batteries exhaust
700 • - SRV recloses ..
700 ----- -- ------
. . .,""RCIC steam .' ." .." .
600line floods----- --I, RPVWater Level
>) 1 + -. in-Shroud
" 500 -............ .......... DowncomerP L...Operator takes manual -TAF
control of RCIC - - BAF400 ---------------------------- - Main Steam Nozzle
A u"r ', t
C
Automatic RCIC300 actuation - Initial debris r
relocation into- - - - - - - - F lowerhead
100 -------I
0 I i I
00 2 4 6 8 10 12 14 16 18 20 22 24
time (hr)
OFFICIAL UY- 34al Informa •
Peach Bottom LTSBO Containment Pressure ResponseNo Mitigation with Portable Equipment
120
100
80
60
40
U)
0-
20
0
0 10 20 30 40 50
time [hr]FEICIAL ONLY-
Pre ecisio al Info-rm-alfo-ný35
-FFCA S Y-P cs al nformat'
Peach Bottom LTSBO Iodine Release and TransportNo Mitigation with Portable Equipment
0
0
4-0
C0
1U
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0 5 10 15 20 25 30 35 40 45 50
time [hr]
OFFICIAL U,5-,ONLY-re isbn Infor' ir-
36
Peach Bottom LTSBO Cesium Release and TransportNo Mitigation with Portable Equipment
0.9
0.8
o 0.7
r- 0.6T
0 0.5
• 0.4
0c 0.30
C0,w 0.2
L.
0.1
00 5 10 15 20 25 30 35 40 45 50
time [hr]
OICIAL P ONL-red e'asi l Information
37
Peach Bottom LTSBONo Mitigation with Portable Equipment
Offsite radioactive release is small
- 2- 4 % release of volatiles, except noble gases- Release is much less severe than 1982 Siting Study (SST1)
* Accident progression timing and emergencyevacuation significantly reduce potentialconsequences
O/F ICIAL U NLY- 38P edeki ýinfori t
*0IAL USE L- Predecisi a
Peach Bottom LTSBONo Mitigation with Portable Equipment
Comparison ofSST1 release'
consequences to 1982 Siting Study's
Early Fatalities (mean) Latent Cancer Fatalities 2 (mean)
LTSBO (without B.5.b) 0 25
1982 Siting Study 92 2700
12
Comparison not based on same assumptions, e.g., different EP model usedSOARCA used dose threshold (5 rem/year, 10 rem lifetime), 1982 Siting Study used LNT
OF CIAL S ONL -
Prede '.io al lnf tion39
Peach Bottom Loss of Vital AC Bus E-1 2
• Initially identified as having CDF>10-6,subsequently determined to be <10-6
• MELCOR analysis showed event to be mitigatedwithout crediting B.5.b equipment
4OFFIC USE 0 LO"P de sion =Inf mationý
40
Peach Bottom Loss of Vital AC Bus E-1 2
" Initiator: Loss of Div IV dc power resulting in
- SCRAM, MSIV closure, containment isolation- RCIC automatically starts, 1 CRDHS pump active
" Operator actions (base case):
- Load shed to maximize duration of DC power- Maximize flow from single CRDHS pump (B.5.b-related)- Depressurize RCS at 1.5 hours- Secure CRDHS from 4- 7 hrs to prevent RPV overfill
" Sufficient to prevent core damage
/ F-,`FIG•I E ONLY- 41Pre*'ec onal In n
Peach Bottom Loss of Vital AC Bus E-1 2Pressure Response
1200
1000
CL
C.
800
600
400
. Start controlled7 depressurization
termnination o'f dc power--l(SlRV recloses)
I
I I I
I
I-hrdc
II ~i
Ii F
200
0 IIII I III
0 2 4 6 8 10 12 14 16 18 20 22 24
time [hr]
cFisýL USýE 9NY-io r=42
Peach Bottom Loss of Vital AC Bus E-1 2Level Response
800Operator takes manual control of RCIC
700 - & opens CRDHS throttle valve
Main Steam Line Nozzles
_ , 600 -.- " -
500
-J
400
" 300 ...... . Start controlled .0 depressurization
--- - - - - - -BAF-
1 0 0 -------------- ------- . .y c lin g S / R V ... . . . . . . .. ......L termination of dc power sticks open
(S/RV recloses)0 -1 i i ' i i I i i I
0 2 4 6 8 10 12 14 16 18 20 22 24
time (hr)
F • A nfor o43Predecisonal~ Inoma ionl
Peach Bottom Loss of Vital AC Bus E-1 2Sensitivities
Sensitivity RCIC Maximize CRDHS Depressurize2 Repressurize Resultsduration CRDHS off to (open SRV) (SRV closes)
flow, prevent(B.5.b) RPV
overfillBaseline 4 hrs 1 hr 4.3 - 7 hrs 1.5 hrs 4 hrs No CDCRD Flow " Not done " " No CDCRD Flow " Not done Not done "" No CDBattery life 2 - 6 hrs Not done Not done " 2 - 6 hrs >3 hr life
averts CDDepressurize 2 - 6 hrs Not done Not done Not done N/A CD, no VF
1 Increases2 Increases
CRHDS flow fromCRDHS flow from
110 to 140 gpm110 to 180 gpm
Injection required to replace water lost by boiling at 4 hours -150 gpm
OFFICIAL UO ONLY- 44
-A S -P dcsonl fraion
Peach Bottom Loss of Vital AC Bus E-12Insights
" Sufficient injection without B.5.b equipment toprevent core damage
- SPAR does not credit CRDHS for coolant makeup
• RPV depressurization and maximizing CRDHS.flow are important operator actions to optimizerecovery
0 SLC (50 gpm) also available for high pressureinjection
" Battery duration is. important
FICIA SE ON -45
-- Pred = nat Informatfion
0
Surry Accident Sequences
" Dominant PRA events
- Long-term SBO (lx1 0-5 to 2xl0-5/yr)- Short-term SBO (lx1 0-6 to 2xl0-6/yr)- ISLOCA (7x10-7/yr)- SGTR (5xl0-7/yr)
° SBO events are due to seismic, flooding and fireinitiators, and are modeled as seismic event
- Internal fire and internal flood events are less challenging, moremitigation available
• ISLOCA and SGTR are due to random equipmentfailures followed by operator errors
kF F FIAL U •ONL 46
Surry LTSBO
* Initial loss of AC power* TD-AFW starts automatically to fill SGs
- At 15 min, operator throttles flow to maintain normal level
* Open SG PORVs for 100 F/hr* Batteries exhaust at 8 hrs
RCS cooldown
• Mitigated- Portable equipment used
to manage TD-AFW andmake up for RCP sealleakage
* UnmitigatedAfter 5 hrs:
" ECST empty• No subsequent
actions taken
FIG LUSE N YPP rre ecd i oon ormattionn
47
ýo ICIL Sý 0 Y-P ecio ýýai
Surry LTSBO
B.5.b mitigation
- Portable air bottles to operate SG PORVs
9 Depressurize and cooldown RCS
- Portable power supply to restore SG and RCS level indication
- Manual operation of TD-AFW without dc power- Portable diesel-driven high-pressure pump for injecting into the
RCS
* Makeup for RCP seal leakage
- Portable diesel-driven low-pressure pump for refillingEmergency CST
Fl U 0ti 48re ecsio I ai
0 S
Surry LTSBO Pressure ResponseSuccessful Mitigation with Portable Equipment
Primary and Secondary PressuresLTSBO - Mitigation with Portable Equipment
18
16
14
120.
2j 1 0
8(/)
6.6
2611
2321
2030
1740
1450 0:3.
1160 w3..
870
580
290
0
4
2
0
0 6 12 18 24
Time (hr)
FFI kLUSEONVY-Pre e risiio ift nfO atio
49
Surry LTSBO Level ResponseSuccessful Mitigation with Portable Equipment
Vessel Water LevelsLTSBO - Mitigation with Portable Equipment
4tAI
Vessel top
8Start RCS Start RC'Scooldown injection with6 . . ..- - - .. portable pump
1iE)
4
2
0
Accumulators.. TA F ......
BAF
Lower head
-2
-4
0 3 6 9 12 15 18 21 24
Time (hr)
•IFIC U ON.L-fr e ec i o~n ti n
50
0 F IAL SE NY ed hs a nform io
Surry LTSBO Seal Leakage vs Injection ResponseSuccessful Mitigation with Portable Equipment
Seal Leakage versus Emergency Diesel Injection FlowLTSBO - Mitigated with Portable Equipment
10 ,Start 150 gpm I
---- RCS injection------------------------ -Total Seal Leakageat 3.5 hr
8-----Emergency Diesel Injection (Kerr)
- -- -- - -- - - -- -- ~- - - - --
S.I I I
0 ---- ------------------- -- - - -- - --- - - - -- - - - - - -- ---
2 - - - - - ----- -- - - - - -- - - - - - ..... ..... -- - -- - - -- -- --
II I
--- Kerr pumnp throttled to----- -- -- -- -- -- -- ---- ---- ---- ---- ---- 5% of capacity (7.5 opm ) - - - -
0 12 24 36 48 60 72 84 96
Time ( hr)
o ICI SEO0 Y- 51red~eis .nal matti
Surry LTSBO
* B.5.b mitigation is sufficient to prevent core damage
- No source term- No offsite health consequences
re ion fo on52
OF IAL U E LY Pr eci ona for.'
Surry Mitigative Measures Sensitivity Analysis
• Long-term SBO - without B.5.b mitigation
- Loss of offsite and onsite AC power- TD-AFW starts automatically to fill SGs
At 15 min, operator throttles flow to maintain normal level
- Open SG PORVs for 100 F/hr RCS cooldown
- TD-AFW lost at 5 hours (Emergency CST empty)- Batteries exhaust at 8 hours
* Accident progression
- Core damage at 16 hrs- Containment failure at 45 hrs (increased containment leakage)- Public evacuation begins at 2.5 hrs
(Predtcn'son'ius hformati n\
Surry LTSBO Pressure ResponseNo mitigation with Portable Equipment
Primary and Secondary PressuresLTSBO - No Mitigation With Portable Equipment
18
16
14
12IL
1• 0
8I)S.-
6
4
2
00 6 12 18 24
Time (hr)
ICI US NLrede ' o I form io
54
;101L1-1 is io a :)o ation
Surry LTSBO Level ResponseNo mitigation with Portable Equipment
Vessel Water LevelsLTSBO - No Mitigation with Portable Equipment
10
4)-j4)
0~
CL
0 3 6 9 12 15 18 21
Time (hr)
• FFCIUSE Ly-4 rdeo ionaS--r~ormation
24
55
Surry LTSBO Containment Pressure ResponseNo mitigation with Portable Equipment
Containment PressureLTSBO - No Mitigation, Calculated RCP Seal Failure
I
0.9
0.8
0.7
CL0.6
0.5
0.4
0.3
0.2
0.1
0
145
131
116
102
87 'R
73 2
58 2
44
29
15
0
0 1 2 3 4
Time (days)
\FFICI L USE NLY-
ýPr eci o I In rmati56
Surry LTSBO Iodine Release and TransportNo mitigation with Portable Equipment
Iodine DistributionLTSBO - No Mitigation, Calculated RCP Seal Failure
I
0.9
0.8
0.7
0r 0.6
- 0.5
o 0.4
U.1!0.3LL
0.2
0.1
Revaporization of ....deposited cavity
=~I92% depositedIn containment
-Containment DepositedContainment Airborne
In-Vessel Total-Env. Release
- - - -- - - - - - - - -- - - - - - - -
Revaporization ofdeposited in-vessel
0.6% environmentalrelease
V _ _ _ _ _
0- -~
0 1 2
Time (days)
rOFF na ON -
Preci onal Informýationý
3 4
57
Surry LTSBO Cesium Release and TransportNo mitigation with Portable Equipment
Cesium DistributionLTSBO - No Mitigation, Calculated RCP Seal Failure
1
0.9
0.8
-- 0.7
0C 0.6
- 0.5.4--0Co0.
0.41! 0.3
U-
0.2
0.1
0
- Containment Deposited
- Containment Airborne
- In-Vessel Total
- Env. Release
85% depostedin containment
-- I- 0.08% environmental
release
RCS Total =15% V
F _N
0 1 2
Time (days)
/-OFFICIA-,SE O -/P re'•• na \kfor. ati'o'-
3 4
58
0
Surry STSBO
* Loss of offsite and onsite AC and DC power* Mechanical failure of TD-AFW" No instrumentation or injection
* Mitigated- At 8 hrs, portable pump
connected to spraysystem
• Unmitigated- No action taken
Pred isi nat In ormation59
Surry STSBO
B.5.b mitigation- SG and RCS injection with portable pump may not be
practical due to accident progression timing andearthquake severity
e Core damage at 3 hrs
* Reactor vessel lower head failure at 7 hrs
- Portable pump (2000 gpm) assumed to be connected tocontainment spray system at 8 hrs
/OF ICIA SEO L- 60Prede is' nal for atio
0 A U
Surry STSBO
Emergency containment sprays
- Portable pump assumed to run until containment filled to1 m above the bottom of the vessel (1 million gallons)
- Ex-vessel debris subsequently boils water in cavity
" Late containment overpressure at 3 days
" No airborne aerosol (only noble gas release to environment)
- Better spray operation possible
" Intermittent
" More water
o ICI L SE Y-61
/ Pred ci ional orma n
6 @ 0FI ALY deci 'o I In rma 'n
Surry STSBO Pressure ResponseMitigation with Portable Equipment
Primary and Secondary PressuresSTSBO
18
16
14
12I'
2-10
8.U)I-
6
4
2
00 1 2 3 4 5 6 7
Time (hr)
O ClISE Y-Pr de ioa, orma
8
62
CIA ON - ~edeinfomt
Surry STSBO Pressure ResponseMitigation with Portable Equipment
Vessel Water LevelSTSBO - Mitigation with Portable Equipment
U)W
.C
10
8
6
4
2
0
-2
-4
0 3. 6 9 12 15 18 21 24
Time (hr)
ýFICI L EEOL-Pre ci jonall Ind ormattionn
63
Surry STSBO Containment Pressure ResponseMitigation with Portable Equipment
Containment PressureSTSBO - Mitigation with Portable Equipment
1
0.9
0.8
0.7
0.6.)= 0.5{/)
0.4
0.3
0.2
0.1
0
145
131
116
102
87 *i
73U)
58 ff
44
29
15
00 2 3 4
Time (days)
=FFI USE/ENLY-Pr ision fr n\
64
Surry STSBO Iodine Release and TransportMitigation with Portable Equipment
Iodine DistributionSTSBO - Mitigated with Portable Equipment
1
0.9
0.8
0.7
0E 0.6
- 0.5046
o 0.4
(US0.3
0.2
0.1
0
88% deposited in containment
-Containment Deposited
- Containment Airborne
- In-Vessel Total
- Env. Release
RCS total11%v
Environmentalrelease = 0.007%
-------------
0 I - 2 3 4
Time (days)
FFICI L EO0 LY-Pre "sionaI In ormation
65
Surry STSBO Cesium Release and TransportMitigation with Portable Equipment
Cesium DistributionSTSBO - Mitigated with Portable Equipment
1
0.9 - ..-.. .. . . . . . 84% deposited in containment
0.8
0.70E 0.6
E0.5
5 0.4-
0.3
0.2
0.1
0
------ ----------------
------ -----------
------------------
----- ----------
-------- ----
-Containment Deposited- Containment Airborne
- In-Vessel Total
--------- Env. Release
RCS total = 15%;
Vf EnionetaI
ýJ- - re EnvironmentalSrelease = 0.003%
-~ - I I
I0 2
Time (days)
3 4
P.,FICIAL USE ONL -
rede al r tion66
0
9/P 1 AL USE -Prede 'ion Infor ion
Surry STSBO
B.5.b mitigation is sufficient to prevent offsiterelease (except noble gases)
- No early fatalities- No latent cancer fatalities
/EFFICI/E 0 NL/ Preeci, onal InIoTrnation
67
0
Surry Mitigative Measures Sensitivity Analysis
" Short-term SBO - without B.5.b mitigation
- Loss of offsite and onsite AC and DC power
- Mechanical failure of TD-AFW
- No indication or injection
" Accident progression
- Core damage at 3 hrs
- Containment failure at 25 hrs
- Public evacuation begins at 2.5 hrs
.FF L USE Y- 68Pr deoisionawormnati
U w
Surry STSBO Containment Pressure ResponseNo Mitigation with Portable Equipment
Containment PressureSTSBO - No Mitigation
1
0.9
0.8
0.7
a-0.6
0 0.5
e 0.4
0.3
0.2
0.1
0
145
131
116
102
87 "C.
73 2
58 2)
44
29
15
0
0 6 12 18 24 30
Time (hours)
FIC USEýPre =siona ormatfion69
Surry STSBO Iodine Release and TransportNo Mitigation with Portable Equipment
Iodine DistributionSTSBO - No Mitigation
I
0.9
0.8
- 0.7
0S0.6 -
E 0.5 -0
o2 0.4-
Lu0.3
0.2
0.1
0
- Containment Deposited
- Containment Airborne
-In-Vessel Total
- Env. Release
Hot leg creeprupture failure
. Rnvironmentalr n n i . . . .. . .. re le a s e 1 %
evaporization in cavity In-vessel revaporization
. . . . . . . .- - - - - - - - - - - - - - -- - - - - - -- - - - - - - - - - - - - -
0 1 2
Time (days)
e._qFIlCn abUSE9raLoY-\/Pre ýci on= Ma Y
3 4
70
0
Surry STSBO Cesium Release and TransportMitigation with Portable Equipment
Cesium DistributionSTSBO - No Mitigation
I
0.9
0.8
-~- 0.7
04' 0.6
o.--8)
-- 0.5.¸
S.-
o 0.4C,
L0 .3
0.2
0.1
0
- Hot leg creep
/ rupture failure
-Containment Deposited
- Containment Airborne
- In-Vessel Total
-Env. Release
I-
Environmentalrelease = 0.4%
~7z7 In-vessel revaporization
------------ \0 .I 2 3 4
Time (days)
OFIC.AUSE 0NjPi e~icnal hAafiion\K
71
0
ICIA S . ecisio In ation
Surry LTSBO and STSBONo Mitigation with Portable Equipment
• SBO sequences without B.5.b measures haverelatively small releases, 1 % or less of.volatileradionuclides
* Comparison of consequences'
.Early Fatalities (mean) Latent Cancer Fatalities 2 (mean)
LTSBO (without B.5.b) 0 0
STSBO (without B.5.b) 0 0
1982 Siting Study 45 1300
12
Comparison not based on same assumptions, e.g., different EP model usedSOARCA used dose threshold (5 rem/year, 10 rem lifetime), 1982 Siting Studyused LNT
0 ICAlU S E 0 "Y,-P'r- i is io na4fW at io6--
72
'0
Surry. SGTR
Break of single tube* Plant response
- HPI, AFW initiate- Turbine stop valves close- Steam dump valves throttle and close- Faulted SG floods at 40 min
* Operator response
- AFW delivery to faulted SG secured by operator on highlevel at 10 min
/O llA ONL 73Predk n~al Iný ion
0
Surry SGTR
SPAR: Operator errors result in core damage
- Fail to depressurize and cool down the RCS
- Fail to refill RWST or cross-connect to unaffected unit'sRWST
- Fail to isolate faulted SG
* SOARCA mitigation measure review
- Concluded that, within a couple of hours, the operators withassistance from TSC and EOF would correct errors
/0 FICIA E ONL - 74/Predecis. nal in r m on
0
O FIC L US Y - Pre "sionallI rma •
Surry SGTRMitigation Starts at 2.5 Hrs
Assumed operator begins mitigation at 2.5 hrs- Operator recognizes SGTR occurred
* SG floods at 40 min even though AFW is secured to that SG
- Operator actions
• Isolate faulted SG (close MS IV)• Secure HHSI* Initiate controlled cool-down (100 deg F/hr) utilizing intact SGs
and steam dump valves* Enter RHR at 4 hrs
MELCOR analysis showed no core damage
=ICIA"SEO0KY ' 75(Prede sonai'nfermation'-ý
Surry SGTRNo Mitigation
Accident progression
- RWST empty at 11 hrs- ECST empty at 1.5 days- Core damage at 2 days
FFICI / SE/Pre ecl ona =n nmat[
76
Surry SGTR Pressure ResponseNo Mitigation
Surry SGTR without Operator Action - System Pressures
2500
2000
' 15000.
1000C.
500
0
0 0.5 1 1.5 2 2.5 3 3.5
Time (days)
FF101 L EQOO
, Pre ' o~nal In ation\,
4
77
00QFF C E ONL - decisio atio
Surry SGTR Vessel Level ResponseNo Mitigation
Surry SGTR without Operator Action - Reactor Vessel Level
35..30 - -- Vessel top
2025. .(cavitation) "....." • G,----- 'i''""
2 0 S G, - -- - -- - -- - -- -I- - - - -- - - - - -25-------- - ----
. .. F- ryp utpen..15falls open.
15 Ac 'SGB_ ' ' ' '-- -- - -- - -- - -- - - -- -S . -- -- -- - -- - -- -- --" ---- ---- -- - -- -w: ', , ... TAF
Z InJection(I) I ...
SI i,
u) 5 -- - - - - -- - - - -- -- - - - - - - --- -- - - -... -- - -- - j -- - -- - - •-- - --
..... BAF
Vessel bottom-10
RWST empt .CST empty :-rI iI ii
I i I
-15
0 0.5 1 1.5 2 2.5 3 3.5 4
Time (days)
11USE NL 78rredel lona ormation
0
Surry SGTR RWST Inventory ResponseNo Mitigation
Surry SGTR without Operator Action - RWST & ECST Inventories
400000
350000 -
300000 1
j250000 -
0 200000 -
.S 150000 -
100000
50000
- - - - - - - - - - -
torile -
F-RWST]-ECST
- - -- - - - - - - - - - -
- - -- - - - - - - - - - -
- - -- - - - - - - - - - -
Useable inventexhaustec
0
0 0.5 I 1.5 2 2.5 3 3.5 4
Time (days)
EFICI SEE NLPrae * onal In ormation
79
Surry SGTRNo Mitigation
Sensitivity: SG PORV on faulted SG sticks opendue to overfill and water passing through valve
- Accident progression
e RWST empty at 9 hours
• Core damage at 1 day
/FFICIA NE ONL/`-/Pre65 onat I tin
80
OFF AL USE 0 - Predecisila ormatio
Surry SGTR - Insights
MELCOR analysis indicates that operators andothers (TSC, EOF) have time to correct errors
- Event can be mitigated with installed (non-B.5.b) equipment
- Other mitigation options exist
* Refill RWST or cross-connect to unaffected unit's RWST
" Use B.5.b pumps to feed RCS and steam generators
* Unmitigated cases have 1 to 2 day delay until coredamage
- Suggests unmitigated case is unrealistic
OFFI CI E ON - 81P dec ional In= ation
'0
Surry ISLOCA
* Failure of LPI check valves' disks resulting in LPI pipebreak in Safeguards Bldg
• Plant response
- HPI, LPI, AFW initiate- 2/3 of HPI goes into cold legs, 1/3 goes out break- LPI pumps stop due to Safeguards Bldg flooding
Subsequently, RWST gravity drains through break
Operator response
- Per procedures, secure 1 HPI pump at 15 min- Shift HPI to hot legs at 45 min- Open SG PORVs for 100 F/hr RCS cooldown
/FFI0CI USEý RY- 82Pr ýion ormation
Surry ISLOCA
• SPAR: Operator error results in core damage
- Fail to refill RWST or cross-connect to unaffected unit'sRWST
• SOARCA migitation measure review
- Concluded that, within a couple of hours, the operatorswith assistance from TSC and EOF would recognize theneed to cross-connect to unaffected unit's RWST
eF CIAL E NLY 83rede 'sion I Inform 10
Surry ISLOCAMitigation with Unaffected Unit's RWST
Operator begins mitigation at 1.75 hours
- Operator recognizes ISLOCA occurred
e Flooding in Safeguards Building and Auxiliary Building
* Initiation of safety injection
- Cross-connect to unaffected unit's RWST at 1.75 .hrs- Start RHR cooling at 6 hrs
* MELCOR analysis showed no core damage
%FIcA' USE LY 84P're c ona omon
0
Surry ISLOCA Geometry Schematic
SafeguardsBuilding
OF FlICA EO Y-Prede nal In aati
85
SF UAC ONL - ýPre ýis~iona~l ath'o
Surry ISLOCA Pressure ResponseMitigation with Unaffected Unit's RWST
Primary and Secondary PressuresISLOCA
18
16
14
12w
01.
10
I-
6
2611
2321
2030
1740.5
1450 &
a.
1160 •
870
580
290
0
4
2
00 3 6 9 12
Time (hr)
FFI CI IbSE 0 L/Pre'dc isonal I rmation
86
Surry ISLOCA Level ResponseMitigation with Unaffected Unit's RWST
Vessel Water LevelISLOCA- Mitigation with Unaffected Unit's Equipment
10
8
Vessel top
E)
CL
6
4
2
0
-2
-40 3 6 9 12 15 18 21
Time (hr)
Pre onal In atVi on
24
87
Surry ISLOCA EGGS Flow ResponseMitigation with Unaffected Unit's RWST
ECCS FlowISLOCA - Mitigation with Unaffected Unit's Equipment
9000
8000
7000
6000
5000
4000
2 x LHSIpumps
-LHSI
-HHS.
3000
2000
1000
0
HHSI #
Isolate LHSI gravity _ -drain from RWST
3
I Secure IHHSI #2
----------- RHR on
+ changeected RWST ....
Break flow a -0 kg/s,HHSI terminated
~' drain
A--- suction to unaff.
0 3 6 9 12
Time (hr)
( POFFI I USE Y
Pisiiona n ormnationi88
SC u -P o faim11-6on
Surry ISLOCA Level ResponseMitigation with Unaffected Unit's RWST
Auxiliary Building Water VolumeISLOCA
600,000
500,000
Aux Bldg Room-Safeguards LPI Ro
---------------- Aux Bldg floodsHHSlmotors at 7'-9"(530,000 gal)
400,000
• 300,000
200,000
100,000
0
-Safeguards LPI Room = 16,660 galAux Bldg at 9.2 hrs = 291,000 galAddition rate -0 gpm
- - - - - - - - - - - - - - - - - - - -- - - - - - - - - --• l
----
--------------
--
I
300 6 12 18 24
Time (hr)
FICI L SEO0 Y-P~re c ion~almat~i
36
89
0
OzffIC UOL-e- oalr o
Surry ISLOCA RWST Level ResponseMitigation with Unaffected Unit's RWST
RWST Water VolumesISLOCA - Mitigated with Unit #2 Equipment
Lu
0)E
0>1
400000
350000
300000
250000
200000
150000
100000
50000
00 6 12 18 24
Time (hr)
o ICIA SE L-ýred is' nal ormattio
30 36
90
0 CIAL US LY - Pr eci& nal Infor a
Surry ISLOCANo Mitigation with Unaffected Unit's RWST
• Accident progression
- RWST empty at 3 hrs* Assumes double-ended break of LHI pipe, resulting in
gravity draining the RWST through the break in 3 hours
- Release. starts at 10 hrs
* Release is scrubbed by water over break
FFICI USEPr de 'jo n a ormnatloý
91
Surry ISLOCA Pressure ResponseNo Mitigation with Unaffected Unit's RWST
Primary and Secondary PressuresISLOCA - No Mitigation with Affected Unit's Equipment
16
14
12
10
6 8U)U)I. 6
4-
2
0
----------------
------------------
100'Fthr cooldown
- - - - - - - - - - - - - -- T
k - -- - - - - -- - - - - -
-------------------------------------
--------------------- ---
-- -- - - - - - - - - - - - - - - -4
- - - - - - - - - - - - - - - -
- - - - - - - - - - - - - - -- - - - - - -
-Pressurizer-SGA
-SG B-SG C
2320
2030
1740
1160
870 C.
580
2900-o
I,
0 6 12 18 24
Time (hr)
FICIA U 0 \Pre cis~inal Info atn
92
Surry ISLOCA Level ResponseNo Mitigation with Unaffected Unit's RWST
10
8
.Vessel Water LevelISLOCA - No Mitigation with Unaffected Unit's Equipment
Vessel top
- ..- ..- ..-.- ..- . .-.- ..- ..- . ........ ....... - -. . - ........ ...
CD
W)
6
4
2
0
-2
-4
0 3 6 9 12 15
Time (hr)
FICA EQPre' si nal=I ai
18 21 24
93
Surry ISLOCA RWST Level ResponseNo Mitigation with Unaffected Unit's RWST
RWST Water VolumeISLOCA - No Mitigation with Unit #2 Equipment
400000
350000,
300000
250000
E 200000
> 150000
100000
50000
0
LPI (2 x 5000 gpm)(before flooding RWST #2
SecureI HSI #3 No cross-tie to---- --------- ------- ------- R W S T #2
6'• -'• HHSI + gravity drain of LPI (1200 - 800 gpm)..
Secure HIHSI #2
RWST #1-..- - - - - - .. . . .RWST #1 EmptyEnd of ECCS
0 1 2 3
Time (hr)
4 5 6.
OFF10 USE L•Y-Prýs d oneisn orma ion
94
Surry ISLOCA Iodine Release and TransportNo Mitigation with Unaffected Unit's RWST
Iodine BehaviorISLOCA - Not mitigated with Unaffected Unit's Equipment
1
0.9Aux Bldg 80%
0 .8 -----------. . . . . . . .. . . . . . . . . . . .. .
0.7--------- --- ----------------- - ------ u~d(~+Dpstd0.7 .......- Aux Bldg (Liq + Deposited)0.6 •-Aux Bldg Airborne
0....... - In-Vessel Total• -Containment Total
0.5 •Environment0l,-
5o 0.4 .. .. ... . ..... . . .... . . .... . . .. . . .. .. .. ... .. . .-~0.5-------------------- ------ -Environmen
0I I
(U.
0.2 __RCS totas - 12%
Environmental Release = 4%
0 0.5 1 1.5 2 2.5 3 3.5 4
Time (days)
0o CIAVD EO0ai 95Pred cJ a ný ýto
Surry ISLOCA Cesium Release and TransportNo Mitigation with Unaffected Unit's RWST
Cesium BehaviorISLOCA - Not mitigated with Unaffected Unit's Equipment
I
0.9
0.8
0.7
0•0.6
- 0.5
o 0.4
0.3
0.2
0.1
0
-Aux Bldg Airborne-Aux Bldg (Liq + Deposited)- In-Vessel Total- Containment Total- Environment
.1 --Aux Bldg = 66%
riI. RCS total m 30%
Environmental Release =2.5%
0 I 2 3 4
Time (days)
,OJffICIAVORSFONLY'- 96
• .
Surry ISLOCA
Insights
- MELCOR analysis indicates that operators and others (TSC,EOF) have time to correct errors
0 Event can be mitigated with installed (non-B.5.b) equipment* Other mitigation options exist
- Use B.5.b pumps to feed RCS and steam generators
- Unmitigated case has scrubbed release
" Suggests small offsite health consequences
" Offsite consequence analysis ongoing
FFICA' E ON - 97Pre ecis nal , r at[ion
10 0
Summary" Peach Bottom LTSBO
- Turbine-driven system (RCIC) and B.5.b prevent core damage- Without B.5.b
* No early fatalities* 25 latent cancer fatalities
" Surry LTSBO- Turbine-driven system (AFW) and B.5.b prevent core damage
- Without B.5.b* No early fatalities* No latent cancer fatalities
" Surry STSBO- B.5.b emergency containment spray prevents environmental
release (except noble gases)- Without B.5.b
" No early fatalities* No latent cancer fatalities
ýFIICI US frLY-Arefon r n
98
Summary
• Peach Bottom and Surry SBO scenarios
- B.5.b provides an additional layer of injection capability
- Sufficient time to implement B.5.b equipment- Accident progression timing (long time to core damage and
containment failure) and mitigative measures significantlyreduce the potential for core damage and/or containment failure
FICI US ONL -- 99Pre ci ion formatlo
4 0 @
Summary" Surry SGTR
- Installed systems (HPI, AFW, RWST) sufficient to prevent core damage- Assuming no mitigation results in 1 - 2 day delay until core damage
* Unrealistic to assume operators delay this long" Surry ISLOCA
- Installed systems (HPI, unaffected unit's RWST) sufficient to preventcore damage
* MELCOR analysis shows 3 hours until RWST depleted- More time available if LHI pipe break is smaller than double-ended
- Assuming no mitigation with unaffected unit's RWST* Release scrubbed by water over break
* Surry bypass scenarios- Accident progression timing (long time to core damage) and mitigative
measures significantly reduce the potential for core damage and/orcontainment failure
- Additional injection capability provided by B.5.b equipment not necessary
/NFF,0 A SE NCY- 100
Pre es•sional n ormati
Reporting Latent Cancer Fatalities
• Commission Paper - Notation Vote* Options
- Range of thresholds (0- 5 rem)- Linear no threshold (LNT)- Estimate point value from Health Physics Society
* 5 rem in one year, 10 rem in a life time
° Staff Analysis
- Estimate point value from Health Physics Society
* 5 rem in one year, 10 rem in a life time
* In staff review
o FICI EON 101Prede-tisional In atrion
0 0o 0 Y d si-n.ll
Status of Pilot Plants
* Peach Bottom, Surry and Sequoyah volunteered• Recommend completing Peach Bottom and Surry,
publishing the results, then solicit additionalvolunteers
- Dialogue with stakeholders and potential volunteers- Solicit additional volunteers
Fl LU N- 102P~re e isiOianformation
46
OF IC LUS NL -Pr e sionall r n
SOARCA SCHEDULE
A " SOARCA Initial Results
" Additional SOARCA Analyses
September 2007
December 2008
- 1 additional plant- Finalize initial results- Source term uncertainty analysis- Additional sensitivity analyses- Peer review
° SOARCA Analyses (up to 5 additional plants)
FFI-, L SE \Pr ~c ional rmayion
TBD
103
