ML13233A068
| ML13233A068 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 07/11/2013 |
| From: | Schimmel M A Northern States Power Co, Xcel Energy |
| To: | Document Control Desk, NRC/RGN-III |
| References | |
| EA-13-096, L-MT-13-062 IR-13-008 | |
| Download: ML13233A068 (99) | |
See also: IR 05000263/2013008
Text
Monticello
Nuclear Generating
PlantXcelEnergy
2807 W County Road 75Monticello,
MN 55362July 11, 2013 L-MT-13-062
U.S. Nuclear Regulatory
Commission
ATTN: Document
Control DeskWashington,
DC 20555-0001
Monticello
Nuclear Generating
PlantDocket 50-263Renewed Facility
Operating
License No. DPR-22Response
to an Apparent
Violation
in NRC Inspection
Report 05000263/2013008
(EA-1 3-096)References:
1) Letter from Nuclear Regulatory
Commission
(NRC) to Mr. Mark A.Schimmel,
"Monticello
Nuclear Generating
Plant, NRC Inspection
Report 05000263/2013008;
Preliminary
Yellow Finding,"
dated June11, 2013 (Accession
Number ML13162A776)
2) Letter from Northern
States Power -Minnesota
to NRC, "Notification
of Intention
Regarding
NRC Inspection
Report 05000263/2013008
(EA-13-096),"
dated June 19, 2013By the above referenced
letter dated June 11, 2013, the NRC transmitted
Inspection
Report 05000263/2013008
for the Monticello
Nuclear Generating
Plant (MNGP). In theinspection
report, the NRC identified
one finding and apparent
violation
with apreliminary
significance
of Yellow for MNGP. In the referenced
letter, the NRC statedthat the site had failed to maintain
a flood procedure,
A.6, "Acts of Nature",
such that itcould support the timely implementation
of flood protection
activities
within the 12 daytimeframe
credited
in the design basis, as stated in the updated safety analysis
report(USAR).Northern
States Power Company -Minnesota
(NSPM) reviewed
the apparent
violation
and, pursuant
to the provisions
of the choice letter, prepared
a written response
to theapparent
violation.
NSPM agrees that the failure to maintain
a flood plan to protect thesite from external
flooding
events is a violation
of Technical
Specification
5.4.1.a.This letter submits additional
information
for the NRC's consideration
in its finaldetermination
of the significance
of the apparent
violation.
The enclosures
address thefollowing:
e-7A
Document
Control DeskL-MT-1 3-062Page 2 of 5Response
to Apparent
Violation
(Enclosure
1)NSPM agrees that the failure to maintain
an adequate
flood plan to protect the site fromexternal
flooding
events is a violation
of Technical
Specification
5.4.1 .a. NSPM is takingthis failure to protect the site from external
flooding
very seriously
and has used it toreinforce
NSPM's policy and commitment
to safety as a top priority
in our Emergency
Response
plans, response
to acts of nature, and effective
corporate
governance
andoversight.
The site and nuclear fleet are taking corrective
actions to ensure protection
ofthe radiological
health and safety of the public in the event of an external
flooding
worstcase scenario.
A summary of the corrective
actions to resolve the performance
deficiency
is presented
in Enclosure
1.As part of those actions,
NSPM is performing
cultural
assessments
focusing
on decisionmaking, effective
communication,
and closure follow-through
not only at the site levels,but across the nuclear fleet to maximize
learning
from this situation.
Probabilistic
Risk Analysis
(Enclosure
2)NSPM developed
additional
information
providing
further insight into the probability
of aProbable
Maximum Flood (PMF) at the Monticello
site for the NRC's consideration.
Thereport provides
probabilistic
risk analyses
to support a best-estimate
assessment
of thesignificance
of this finding as well as bounding
analyses
to support final significance
determination
prior to corrective
actions taken by the site. The best-estimate
analysisincorporated
the assumptions
necessary
to support the assessment
of a finding relatedto an external
flooding
event. Results are shown in the table below:Nominal,
Best Sensitivity
1: Sensitivity
2:Estimate
Bounding
Flood SPAR-H HRAFreauencv
Probabilities
CDF 1.04E-06
3.1 OE-06 1.83E-06ACDP 8.92E-07
2.66E-06
1.57E-06The full results of the event tree quantification
are summarized
in Enclosure
2.Monticello
Nuclear Generating
Plant Flood Protection
Analysis
(Enclosure
3)The postulated
to other site Mississippi
river conditions
in the table below. The PMF is not an instantaneous
event, but rather a slowlydeveloping
evolution
that allows for plant staff to monitor,
predict,
prepare,
andimplement
appropriate
actions to provide the required
flood protection.
Since actionshave been taken to procure the bin wall and levee materials,
performance
of areasonable
simulation
demonstrated
that the levee and bin wall system can now beinstalled
within the available
time as defined in the licensing
basis.
Document
Control DeskL-MT-1 3-062Page 3 of 5Normal and Flooded River Flow Rates and Water Elevations
River Flow Rate (cfs) Water Elevation
Condition
(ft. msl)Normal 4,600 905Maximum Recorded
51,000 916(1965)1000 Year Flood -90,000 (1) 921Probable
Maximum 364,900 939.2Flood 364,900_
939.2A report entitled
"Monticello
Flood Protection,"
was prepared
for Monticello
andaddresses
the aspects of flood protection
for which MNGP was licensed
and is includedin Enclosure
3.Annual Exceedance
Probability
(Enclosure
4)Annual river exceedance
probabilities
based on annual peak flood estimates
at theMonticello
site were developed
to support the probabilistic
risk assessment.
Theprobability
of a PMF at the site was determined
to be extremely
low.Enclosure
4 provides
a copy of the report entitled,
"Annual Exceedance
Probability
Estimates
for Mississippi
River Stages at the Monticello
Nuclear Generating
Plant basedon At-site Data for Spring and Summer Annual Peak Floods",
June 28, 2013, developed
by RAC Engineers
& Economists.
Stakeholder
Outreach
(Enclosure
5)NSPM hosted an open house to share information
with its community
neighbors
on itsoperations
and preparedness
to handle potential
emergencies
and how it would respondto flooding,
and other unforeseen
challenges.
The key message presented
to visitors
was that safety and security
at the NSPM nucleargenerating
plants are top priorities
for Xcel Energy. Further,
that we understand
theindustry,
NRC, and public's
demand of higher safety standards
and flood preparedness
at the nation's
nuclear power plants in the wake of events such as 9/11 and Fukushima
Daiichi.
The Monticello
Flood Protection
Strategy
was identified
and explained
todemonstrate
that the site is capable of withstanding
a PMF and that the site isincorporating
lessons learned from the industry
to improve and assure protection
methods.Safety Culture ReviewNSPM agrees it missed an opportunity
within its control to identify
challenges
to theimplementation
of the A.6 procedure,
leading to the identified
apparent
violation.
Assuch, NSPM assembled
an expert panel to examine the behavioral
and cultural
aspectsimpacting
decision
making within the nuclear business
unit. This activity
was chartered
Document
Control DeskL-MT-13-062
Page 4 of 5as an immediate
and interim measure preceding
the extensive
root cause evaluation
that will be performed
to identify
the full magnitude
of this issue, associated
causes, andcorrective
actions to prevent recurrence.
This expert panel assembled
to examine safety culture within its nuclear organization
was comprised
of five independent
consultants
and one Xcel representative.
The teamreported
directly
to the Vice President
of Nuclear Operations
Support.
A phasedapproach
is being utilized
to examine the behavioral
and cultural
aspects impacting
decision
making within the nuclear business
unit. Three phases are planned to examinethis subject:
Phase (1) is specifically
focused on the Monticello
flooding
issue, Phase (2)more broadly examines
Monticello
issues and Phase (3) examines
Prairie Island issues.While the phases are specific
to the individual
sites, the scope includes
developing
anunderstanding
of the corporate
culture and influence
beyond a site-centric
examination
of the behavioral
and environmental
influences.
To date Phase (1) has been completed
with scheduling
of Phase (2) and (3) expected
to commence
and complete
over the nextfew months. The initial phase identified
improvement
opportunities
in the areas ofdecision
making, leadership
behaviors,
and questioning
attitude
regarding
the station's
preparedness
for a PMF. The results of this assessment
have been insightful
and will beapplied across the nuclear fleet to ensure a healthy safety culture exists. Opportunities
have been identified
to strengthen
fleet and Nuclear Oversight
accountability
forproviding
oversight
to proactively
detect performance
gaps.Interim actions are in place for the short term to focus on the areas for improvement,
andlonger term actions are in development.
SummaryNSPM respectfully
requests
that the NRC consider
the enclosed
information
in its finaldetermination
of the significance
of the finding.
Notwithstanding
our assessment
of thesignificance
of the finding,
NSPM clearly understands
our performance
shortcomings
concerning
flood protection
for the entire spectrum
of possible
flooding
events at theMNGP. Corrective
actions have already been completed
to address the NRC's identified
performance
deficiency.
Additionally,
we unequivocally
acknowledge
the need for overallperformance
improvement
at MNGP. Actions are underway
to ensure that the lessonslearned from this finding are applied more broadly to overall performance.
Summary of Commitments
This letter contains
no new commitments
and no revisions
to existing
commitments.
Mark A. SchimmelSite Vice-President
Monticello
Nuclear Generating
PlantNorthern
States Power Company-Minnesota
Document
Control DeskL-MT-1 3-062Page 5 of 5Enclosures:
Enclosure
1 -Response
to Apparent
Violation
Enclosure
2 -External
Flooding
Evaluation
for Monticello
NuclearGenerating
PlantEnclosure
3 -Monticello
Flood Protection
Enclosure
4 -Annual Exceedance
Probability
Estimates
Enclosure
5 -Stakeholder
Outreachcc: Regional
Administrator,
Region III, USNRCProject Manager,
Monticello
Nuclear Generating
Plant, USNRCResident
Inspector,
Monticello
Nuclear Generating
Plant, USNRC
Enclosure
IResponse
to Apparent
Violation
EA-1 3-096NRC Inspection
Report 05000263/2013008
Monticello
Nuclear Generating
Plant3 Pages Follow
Northern
States Power Company -Minnesota
Response
to Preliminary
Yellow FindingNRC Finding SummaryThe inspectors
identified
a preliminary
Yellow finding with substantial
safety significance
andassociated
apparent
violation
(AV) of Technical
Specification
5.4.1 for the licensee's
failure tomaintain
a flood plan to protect the site from external
flooding
events. Specifically,
the site failedto maintain
flood Procedure
A.6, "Acts of Nature,"
such that it could support the timelyimplementation
of flood protection
activities
within the 12 day timeframe
credited
in the designbasis as stated in the updated safety analysis
report (USAR).The inspectors
determined
that the licensee's
failure to maintain
an adequate
flood planconsistent
with the USAR was a performance
deficiency,
because it was the result of the failure tomeet the requirements
of TS 5.4.1 .a, "Procedures;"
the cause was reasonably
within thelicensee's
ability to foresee and correct;
and should have been prevented.
The inspectors
screened
the performance
deficiency
per Inspection
Manual Chapter (IMC) 0612, "Power ReactorInspection
Reports,"
Appendix
B, dated September
7, 2012, and determined
that the issue wasmore than minor because it impacted
the 'Protection
Against External
Factors'
attribute
of theMitigating
Systems Cornerstone
and affected
the cornerstone's
objective
to ensure theavailability,
reliability,
and capability
of systems that respond to initiating
events to preventundesirable
consequences
(i.e. core damage).
Specifically,
if the necessary
flood actions cannotbe completed
in the time required,
much of the station's
accident
mitigation
equipment
could benegatively
impacted
by flood waters.NRC Baseline
Significance
Determination
Process ReviewAs part of the process,
the Region III Senior Reactor Analyst (SRA) developed
an event treemodel to perform a bounding
quantitative
evaluation.
The model presents
an external
flood eventthat exceeds grade level (930 ft. MSL) and requires
implementation
of Procedure
A.6, "Acts ofNature" Section 5.0.NSPM ResponseNSPM agrees that a performance
deficiency
exists. Procedure
A.6, "Acts of Nature",
at the time ofthe violation,
did not provide sufficient
guidance
to execute mitigation
strategies
for a probablemaximum flood (PMF) event. Adequate
management
oversight
and engagement
was notprovided
to ensure that the Monticello
external
flood mitigation
procedure
and strategies
metexpected
industry
standards
and licensing
basis requirements.
Actions have been completed
to reduce the flood mitigation
plan timeline
by pre-staging
equipment
and materials
required
for bin-wall
levee construction,
improving
the quality of theA.6 "Acts of Nature" procedure
and pre-planning
work orders necessary
to carry out the A.6actions.Summary of Corrective
Actions:Acquired
materials
required
for flood mitigation
including,
but not limited to:" Hardware
and components
for construction
of Bin-Wall" Clay for levee construction
(30000 cubic yards)* Rip-Rap stone for levee construction
(1700 cubic yards)Page 1 of 3
- Sand for levee construction
and filling sandbags
(11000 cubic yards)" Sand bagging machine (Capacity
1600 sand bags/hr)* Manual sand bag filling tools (25 on site)" Gas Sump Pumps* Electric
Sump Pumps" Crushed concrete
for alternate
road access (2400 cubic yards)* Preventative
maintenance
plans are being developed
for new flood mitigation
equipment
- Performance
of reasonable
simulation
of major steps required
by procedure
A.6 "Acts ofNature" Section 5.0, including
building
of bin-wall
sections,
sandbagging,
placement
ofvarious covers, and relocation
of vital equipment.
- Extensive
procedure
revisions
to enhance feasibility
of actions and reduce overall timerequired
to execute the strategy.
- Table top exercises
of new revisions
performed
to ensure practicality.
- Development
of work orders to provide more detail for execution
of steps within procedure
A.6, "Acts of Nature" Section 5." The existing
flood prediction
surveillance
was revised to occur on a monthly basis insteadof yearly and contains
provisions
to continually
monitor river predictions
if certainconditions
are met.* Meetings
with the National
Weather Service were held to develop more robust prediction
capabilities
and options.* Enhanced
construction
drawings
of levee and bin-wall
to provide more detail* Updated existing
contracts
and memorandums
of understanding
with vendors to assureequipment
availability.
- A modification
is also in the design phase to install the base of the bin-wall
on the westside of the Intake structure,
simplify
construction
on the east side of the Intake Structure,
and also update the steel plate design for protection
of the Intake Structure.
Review of NRC Significance
Determination
NSPM has developed
additional
information
providing
new insight into the probability
of a PMF atthe Monticello
site for your consideration.
A report entitled
"External
Flooding
Evaluation
forMonticello
Nuclear Generating
Plant" was prepared
by Hughes Associates,
Inc., for NSPM. Thereport provides
a best-estimate
assessment
of the significance
of this finding.
Two (2)sensitivities
were performed
to assess the bounding
risk, addressing
some of the uncertainty
associated
with this assessment.
The first sensitivity
study provides
the risk assessment
if a bounding
annual exceedance
probability
is assumed.
As noted in the Hughes' report, the uncertainty
associated
with extremeflooding
can be addressed
by artificially
restraining
the AEP to a value of no less than 1 E-05/year.
When this restraint
is assessed,
the ACDP is 2.66E-06.
Enclosure
4 of this letter provides
a copy of the report entitled,
"Annual Exceedance
Probability
Estimates
for Mississippi
River Stages at the Monticello
Nuclear Generating
Plant based on At-site Data for Spring and Summer Annual Peak Floods",
June 28, 2013, developed
by RACEngineers
& Economists.
The second sensitivity
address the different
methodologies
available
for quantifying
the HumanError Probability
(HEP) associated
with the manual operation
of RCIC (Reactor
Core Isolation
Cooling)
and HPV (Hard Pipe Vent). This sensitivity
provides
quantification
using The SPAR-HPage 2 of 3
Human Reliability
Analysis
Method, NUREG/CR-6883.
When the simplified
SPAR-Hmethodology
is used, the assessment
results in a ACDP of 1.57E-06.
The result of the nominal,
best-estimate
assessment
and the two (2) sensitivities
performed
areshown in the table, below, for ease of reference.
Sensitivity
1:Bounding
FloodFrequency
Sensitivity
2: SPAR-HHRA Probabilities
Nominal Best-EstimateCDF 1.04E-06
3.1OE-06
1.83E-06ACDP 8.92E-07
2.66E-06
1.57E-06Enclosure
2 of this letter provides
a copy of a report entitled,
Report Number 1SML16012.000-1,
"External
Flooding
Evaluation
for Monticello
Nuclear Generating
Plant," developed
by HughesAssociates
for consideration.
Page 3 of 3
Enclosure
2Monticello
Nuclear Generating
Plant"External
Flooding
Evaluation
for Monticello
Nuclear Generating
Plant"ISMLI16012.000-1
Hughes Associates
62 Pages Follow
.IHUGHESEASSOCIATES
ENGINEERS
CONSULTANTS
SCIENTISTS
External
Flooding
Evaluation
for Monticello
Nuclear Generating
Plant1SML16012.000-1
Prepared
for:Xcel EnergyProject Number: 1SML16012.000
Project Title: Monticello
External
Flooding
SDPRevision:
1Name DatePreparer:
Erin Collins/Paul
Amico/Suzanne
Loyd 7/8/2013~ ~" Erin P. Collins2013.07.082018:01
-04-00-Reviewer:
Pierre Macheret
7/8/2013P.",: 2"13 007 .M0 1-. o U.Review Method Design Review E] Alternate
Calculation
E]Approved
by: Francisco
Joglar Francisco
Joglar. ,. 7/8/2013N. I l: "013.07-
ISML-16012.000-1
Table of ContentsTABLE OF CONTENTS1.0 INTRODUCTION
..................................................................................................
12.0 REFERENCES
.................................................................................................
23.0 METHODOLOGY
and analysis
........................................................................
43.1 Event Tree Analysis
.............................................................................
43.1.1 Evaluation
of Flood Frequency
...................................................
43.1.2 Early W arning Probability
...........................................................
73.1.3 Protection
of the Reactor Building
...............................................
73.1.4 Manual Local Operation
of RCIC and the Hard Pipe Vent ..........
84.0 CONCLUSIONS
.............................................................................................
15APPENDICES
TABLE OF CONTENTS
...................................................................
16Revision
I Page ii
1SML16012.000-1
Introduction
1.0 INTRODUCTION
This analysis
was developed
to address the significance
of a finding that was received
by theMonticello
Nuclear Generating
Plant (MNGP) associated
with External
Flooding
hazards.
ThisSDP is summarized
in NRC Letter EA-13-096
(Reference
5). The analysis
quantifies
the coredamage frequency
associated
with a flood exceeding
930' at MNGP.Revision
2 Page 1Revision
2Page1I
ISML16012.000-1
References
2.0 REFERENCES
1. Annual Exceedance
Probability
Estimates
for Mississippi
River Stages at the Monticello
Nuclear Generating
Station based on At-Site Data for Spring and Summer Annual PeakFloods, David S. Bowles and Sanjay S. Chauhan,
RAC Engineers
and Economists,
June28, 2013.2. Hydrologic
Atlas of Minnesota,
Division
of Water, Department
of Conservation,
State ofMinnesota,
1959.3. US Geological
Survey, Guidelines
for Determining
Flood Flow Frequency,
Bulletin#17B, Hydrology
Subcommittee,
Interagency
Committee
on Water Data, Office of WaterData Coordination,
1982.4. A Framework
for Characterization
of Extreme Floods for Dam Safety Risk Assessments,
Robert E. Swain, David Bowles and Dean Ostenea,
Proceedings
of the 1998 USCOLDAnnual Lecture,
Buffalo,
New York, August 1998.5. NRC Letter EA-13-096,
Subject:
Monticello
Nuclear Generating
Plant, NRC Inspection
Report 05000263/2013008;
Preliminary
Yellow Finding,
United States NuclearRegulatory
Commission,
Region III, 11 June 2013.6. A Preliminary
Approach
to Human Reliability
Analysis
for External
Events with a Focuson Seismic,
EPRI 1025294,
EPRI, December
2012.7. Interim Staff Guidance
for Performing
the Integrated
Assessment
for External
Flooding,
Appendix
C: Evaluation
of Manual Actions,
Revision
0, U.S. NRCJapan Lessons-Learned
Project Directorate,
November
30, 2012.8. Job Performance
Measure JPM-A.8-05.01-001,
Manual Operation
of RCIC, Rev. 0, TaskNumber NL217.108
-Operation
of RCIC without Electric
Power, 3 timed exercises
performed
17 June 2013.9. Job Performance
Measure JPM-A.8-05.08.001,
Manually
Open Containment
Vent Lines,Rev. 0, Task Number FB008.007,
4 timed exercises
performed
17 June 2013.10. Hughes Associates
Record of Correspondence,
RCIC Manual Operation
e-mails withXcel Energy during June -July 2013, Hughes Associates,
Baltimore,
MD, 7 July 2013.11. Hughes Associates
Record of Correspondence,
Hard Pipe Vent Manual Operation
e-mails with Xcel Energy during June 2013, Hughes Associates,
Baltimore,
MD, 7 July2013.12. Monticello
Procedures:
" 8900, OPERATION
OF RCIC WITHOUT ELECTRIC
POWER, Revision
2" C.5-1 100, RPV CONTROL flowchart,
Revision
11" C.5-1200,
CONTROL flowchart,
Revision
16" C.5-3505-A,
Revision
10* A.6, ACTS OF NATURE, Revision
43* A.8-05.08,
Manually
Open Containment
Vent Lines, Revision
1Revision
2Page 2
ISML16012.000-1
References
0 A.8-05.01,
Manual Operation
of RCIC, Revision
Software
Users Manual, Version 4.21, EPRI, Palo Alto, CA,and Scientech,
a Curtiss-Wright
Flow Control company,
Tukwila,
WA.14. NUREG/CR-1278,
Handbook
of Human Reliability
Analysis
with Emphasis
on NuclearPower Plant Applications,
(THERP) Swain, A.D. and Guttman,
H.E., August 1983.15. NUREG-1921,
EPRI/NRC-RES
Fire Human Reliability
Analysis
Guidelines,
DraftReport for Public Review and Comment,
November
2009.16. NUREG- 1852, Demonstrating
the Feasibility
and Reliability
of Operator
Manual Actionsin Response
to Fire, October 2007.17. NUREG/CR-1278,
Handbook
of Human Reliability
Analysis
with Emphasis
on NuclearPower Plant Applications,
(THERP) Swain, A.D. and Guttman,
H.E., August 1983.18. Whaley, A.M, Kelly, D.L, Boring, R.L. and Galyean,
W.J, "SPAR-H Step-by-Step
Guidance",
INL/EXT-10-18533,
Revision
2, Idaho National
Laboratory,
Risk,Reliability,
and NRC Programs
Department,
Idaho Falls, Idaho, May 2011.Revision
2 Page 3Revision
2Page 3
1SML16012.000-1
Methodology
and Analysis3.0 METHODOLOGY
AND ANALYSIS3.1 Event Tree AnalysisEvent trees were developed
to calculate
the core damage frequency
(CDF) associated
withExternal
Floods. Event trees were developed
for both a best estimate
case as well as sensitivity
cases. Floods were evaluated
at three particular
heights -917' but less than 930', 930' but lessthan 935', and greater than or equal to 935'. The first flood height range (917' to 930') wasevaluated
for frequency
but was not deemed feasible
to cause core damage since much of theplant's critical
safety equipment
is not threatened
unless flood levels exceed the 930' elevation.
The following
sections
describe
the development
of the flood frequency
and conditional
probabilities
of the other events that may lead to core damage events.Additionally,
it is agreed that, as stated in the NRC letter EA- 13-96 (Reference
5), the evaluation
of large early release frequency
(LERF) risk is assumed to be no more significant
than CDF-based risk; therefore,
no evaluation
of LERF was performed
for this analysis.
3.1.1 Evaluation
of Flood Frequency
MNGP teamed with industry
experts to evaluate
the frequency
of major floods in detail. Dr.David Bowles was the lead author for the flood frequency
analysis.
To ensure that the floodfrequency
of exceedance
analysis
was sound, an independent
review of the analysis
wasperformed
as part of this analysis
(Reference
1). The review resulted
in some recommendations
for improvement
that were incorporated
by Dr. Bowles and his team prior to the development
ofthe event trees that are included
in this report. This section documents
the results of that finalflood frequency
analysis.
The frequencies
of Mississippi
River floods at MNGP for flood heights of 917', 930' and 935'were estimated
using stream-flow
data from 1970 -2012. This estimation
is described
in"Annual Exceedance
Probability
Estimates
for Mississippi
River Stages at the MNGP based onAt-Site Data for Spring and Summer Annual Peak Floods" (Reference
1).Separate
flood frequency
relationships
were developed
for spring and summer annual peakfloods based on the Hydrologic
Atlas of Minnesota
(Reference
2) and an examination
of flowrecords.a) Spring annual peak floods generally
peaked in the period March to May, but if it wasclear from examination
of the hydrograph
that a snow melt flood event peaked in Junethen that peak was used.b) Summer annual peak floods generally
peaked in June to October,
but flood peaks in Juneassociated
with snow melts were excluded
since they were assigned
to spring floods.Frequencies
were estimated
based on extrapolation
of flood frequency
relationships
developed
from at-site flow data. The mean daily annual peak stages were obtained
for spring and summerannual peak floods. The daily annual peak stages were converted
to daily annual peak flows forspring and summer floods using a combined
rating curve described
in Reference
1. TheExpected
Moments Algorithm
(PeakfqSA)
was applied using methodology
described
in thecurrent draft of the upcoming
revision
to USGS Bulletin
17B (Reference
3). The EMA softwareprovided
annual exceedance
probability
(AEP) estimates
down to 1 in 10,000/yr.
Annual peakdischarge
was plotted on a Log scale and AEPs on a z-variate
scale (corresponding
to a NormalRevision
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ISML16012.000-1
Methodology
and Analysisprobability
distribution)
to allow AEPs lower than 1 in 10,000/yr
to be estimated
by linearextrapolation.
The resulting
median estimates
for spring and summer floods at 917', 930' and 935' river heightswere as follows:Table 3-1 Median Flood Frequency
Estimates
at MNGP Site (Ref. 1)Elevation
917' Elevation
930' Elevation
935'Spring Floods 6.3E-3/yr
<lE-9/yr
<1E-9/yrSummer Floods 1.7E-3/yr
<1E-9/yr
<1E-9/yrA full family of flood hazard curves is provided
in the Bowles report. There is a substantial
amount of aleatory
uncertainty
in the development
of these curves, resulting
in very wideconfidence
bounds as can be seen in the figures and tables in the report, especially
for the floodlevels of interest.
For example,
the elevation
917' 95th percentile
estimate
is 3.4E-2/yr
and the5th percentile
estimate
is 5.9E-7/yr
for spring floods. This is indicative
of the limited dataavailable
in the 1970 -2012 year period. In addition,
not all potential
flood influences
were seenin the 42 years of experience.
Moreover,
there is additional
epistemic
uncertainty
due tosimplifications
used in the modeling
process,
For example,
regional
flood impacts were notconsidered,
nor were the potential
effect of ice blockage
or changes in flood protective
featuressuch as dikes along the river. To address these as well as other potential
flood contributors,
themean hazard for the purposes
of quantification
will be represented
by the 84th percentile,
whichis the median plus one standard
deviation
for a lognormal
form distribution.
This is a commonpractice
to provide margin to account for the uncertainties.
As a further consideration,
there is a general consensus
that the practical
limit on AEPextrapolation
is no better than 1.OE-5/yr
no matter how much information,
including
information
on paleofloods,
is available
(see for example,
"A Framework
for Characterization
of ExtremeFloods for Dam Safety Risk Assessments"
(Ref. 4). It is believed
that all of these factors wouldtend to increase
the estimated
frequency
of floodings.
Some of these uncertainties
could beaddressed
in a more detailed
analysis,
such as a Monte Carlo rainfall-runoff
approach,
but others,such as the potential
effect of ice blockage,
would remain. In the case of this evaluation,
thereadditional
factors will be addressed
by way of a sensitivity
study, discussed
at the end of thissection.The 84th percentile
is the median plus one standard
deviation,
which is a common "marginvalue" that addresses
uncertainty
without being overly conservative.
The margin is to cover thewide statistical
uncertainty
in the distribution
plus the modeling
uncertainty
that comes fromsome of the issues we discussed,
such as not considering
ice blockage
or other downstream
flowbottlenecks,
only considering
site data, and not actually
modeling
the flows and performing
asimulation.
This results in the following
flood frequency
estimates:
The results presented
in the Bowles report support the use of the 84th %-tile as a reasonable
conservative,
but not overly conservative,
representation
of the mean. A manually
generated
approximation
of the mean (described
in Ref. 1 -the code used cannot itself generate
a mean) isshown to be in the range of the 70th percentile,
plus or minus about 10 percentile.
This is theresult of the aleatory
uncertainty.
The use of the 84th percentile
provides
some additional
Revision
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1SM L16012.000-1
Methodology
and Analysismargin to account for epistemic
uncertainty
and give confidence
that the "true mean" is notlikely to exceed this value.Treating
the 84th percentile
as the mean, the process of developing
the initiating
eventfrequencies
is straightforward.
It is typical in external
hazard PRA to create initiating
events bydiscretizing
the hazard curve. Because for external
flooding
there are a clear series of floodlevels of concern,
the selection
of the initiating
events is clear. For MNGP, the levels of concernare 917', 930', and 935', with the exceedance
of each level causing the same impact on plantsystems until the flood exceeds the next level of concern.
Therefore
the initiating
events can bedefined as follows:" IE1 -level >917' and <930'" IE2 -level >930' and <935'" IE3 -level >935'Using the 84th percentile
values to represent
the mean, we get exceedance
probabilities
for eachlevel of concern as follows:Table 3-2 84th Percentile
Exceedance
Frequencies
(Used as Means) (Ref. 1)Elevation
917' Elevation
930' Elevation
935'Spring Floods. 2.0E-02/yr
7.5E-08/yr
<1E-09/yr
Summer Floods 8.8E-03/yr
8.8E-06/yr
9.7E-07/yr
Total 2.9E-021yr
8.9E-061yr
9.7E-071yr
The values for spring and summer can be summed because they are each calculated
on a per-calendar-year
basis and because we are using these values to represent
the "true mean" of thedistribution,
albeit conservatively.
Because these values are exceedance
(i.e., the frequency
that a flood exceeds a specified
level),the way to determine
the frequency
of a flood in a given range is to subtract
the frequency
ofexceedance
of the upper flood in the range from the frequency
of exceedance
of the lower floodin the range.One event tree was developed
to account for all floods that were greater than 930' (including
those greater than 935'). The frequency
of exceedance
for the 930' floods was used and aconditional
probability
was applied to account for the floods within the 930' to 935' range andfloods greater than 935'. The frequency
shown as IE2 in Table 3-3 was used in the event tree.The conditional
probability
that the flood was indeed greater than 935' was then applied in asubsequent
branch to determine
the CDF for sequences
specific
to floods greater than 935'(value of 0.109). Table 3-3 below shows the initiating
event frequencies
used for thisassessment.
Revision
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1 SML16012.000-1
Methodology
and AnalysisI SMLI 6012.000-1
Methodology
and AnalysisTable 3-3 Best Estimate
Initiating
Event Frequencies
Initiating
Event Initiating
Event Frequency
IEl1 2.9E-02/yr
IE22 8.90E-06/yr
Not deemed feasible
for core damage sequences.
Not evaluated
for this analysis.
2This frequency
Is represented
in the event tree along with a conditional
probability
that the flood will be >935' toevaluate
the correct range of flood heights.As discussed
earlier,
there is the question
of the practical
limit of extrapolation
of flooding
data.Therefore,
in addition
to the initiating
event frequencies
presented
above, a sensitivity
analysiswas performed
limiting
the flood frequency
to no less than 1.OE-5/yr,
consistent
with theconsensus
reached in Ref. 4 concerning
the limit of credible
extrapolation
for annual floodexceedance
probability.
Table 3-4 Sensitivity
Case Initiating
Event Frequencies
Initiating
Event Initiating
Event Frequency
IE1 2.9E-02/yr
IE22 2.OE-05/yr
'Not deemed feasible
for core damage sequences.
Not evaluated
for this analysis.
2This frequency
is represented
In the event tree along with a conditional
probability
that the flood will be >935' toevaluate
the correct range of flood heights.It could be argued that the limit should apply across the 930' events (i.e., that the hazard curvegoes flat at 1E-5/yr)
and that it is sufficient
to ignore the 935' event (because
F(IE2930<=1v1<935)
=fexceed(930)
-fcxceed(935)
= 0) and simply evaluate
the 930' flood at a frequency
of lE-5/yr.
Sincethis is a sensitivity
case and not the best estimate,
it was decided to assign 2E-5/yr to IE2 forpurposes
of providing
the sensitivity
insights
and use a conditional
probability
of 0.5 to accountfor floods that are >935'.In the event trees (shown in Appendix
A), the flood frequencies
are represented
by the headings"EXTERNAL
FLOOD >930"' and "<935.' for IE2 events. In addition,
event trees used forsensitivities
have similar headings.
3.1.2 Early Warning Probability
Although
it was considered
qualitatively,
there was no basis determined
for giving credit to thepotential
for early warning of a flood >930'. The event tree model shows a failure probability
of1.0 for this node.3.1.3 Protection
of the Reactor BuildingIn the event of a major flood, such as those evaluated
in this analysis,
MNGP plans to build a binwall barrier that will protect the site from the high flood waters. If the bin wall levee issuccessful,
the safety equipment
needed to prevent core damage will be protected,
providing
defense in depth for each required
critical
safety function.
Simple flood protection
measuresmay be taken to protect the reactor building
from floodwater,
even if the bin wall levee fails.These measures
to protect the reactor building
do not need to be in place until the flood heightapproaches
the 935' elevation.
A conservative
value of 0.11 is assigned,
consistent
with the ES-13-096 NRC letter (Reference
5), to the failure probability
of protecting
the reactor building.
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1SML16012.000-1
Methodology
and Analysis3.1.4 Manual Local Operation
of RCIC and the Hard Pipe VentMNGP requested
Hughes Associates
to conduct a detailed
human reliability
analysis
(HRA) toestimate
human error probabilities
for operator
manual actions to prevent core damage throughthe use of RCIC as a high pressure
injection
source and the Hard Pipe Vent (HPV) to removedecay heat from containment.
This detailed
HRA was based upon thermal/hydraulics
analyses,
battery depletion
calculations,
several Job Performance
Measure (JPM) exercises
for the specificprocedure
A8.05.01
and A8.05.01
actions (References
8 and 9) considering
flood and StationBlackout
(SBO) conditions,
and discussions
with Operations
and PRA staff (References
10 and11). This section documents
the initial conditions
assumed,
the analytical
process,
and theresults of the detailed
HRA. A comparison
between the detailed
analysis
results and thoseobtained
using SPAR-H is also provided
as a sensitivity
evaluation.
3.1.4.1 Initial Conditions
for the Operator
Manual ActionsOperations
staff at MNGP provided
the following
information
on the conditions
that would beevolving
leading up to the need for the postulated
operator
manual actions evaluated
in thisHRA.The A.6 Procedure,
"Acts of Nature" (Reference
12) that addresses
External
Flooding
directs de-energizing
the 115 KV, 230 KV and 345 KV substations
for flood levels in excess of the 930'elevation.
In the case where the flood level is above 930' this would lead to a loss of offsitepower and reliance
on the EDGs. Since the normal long term fuel oil storage (Tank T-44) for theEDG's is not evaluated
to survive flood levels above 932' elevation,
and alternate
fuel oil makeupmethods are not pre-prescribed
to support the EDG's, long term EDG operation
is not easilydefensible
utilizing
existing
procedures.
Additionally,
there are several penetrations
in the PlantAdministration
Building
that would make positive
flood proofing
of the building
difficult,
leaving three of the four station batteries
vulnerable
to flooding.
The flooding
engineer
provides
daily updates to the station on high river water levels including
potentials
to rise above any trigger points from the A.6 procedure.
At this point, heightened
awareness
of the potential
for flooding
is implemented.
When river level exceeds 921 feet an evaluation
of EALs would be performed.
If visible damagehas occurred
due to flood water rising greater than 921 feet, then an Alert per EAL HA1.6 wouldbe declared.
Prior to the river reaching
these levels, operators
would be walking down the procedures
foralternate
methods to vent primary containment
and operate RCIC remotely.
This would involvestaging of equipment
in the torus area to open the Hard Pipe Vent and verification
thatequipment
is properly
staged to operate RCIC remotely.
As water level reached the 930' elevations,
Operations
would prepare for isolation
of off-sitepower and loading essential
loads onto the emergency
diesel generators
as needed to conservefuel. Only a single EDG is required
for shutdown
cooling and inventory
makeup. Operators
would be in the EDG rooms, intake and other critical
areas ensuring
no water intrusion
andwould be pumping water out of the room as needed. Also the battery rooms in the PAB wouldbe of concern due to the high flood levels. At this point operators
would be briefed to be readyto operate RCIC without electrical
power as necessary.
Revision
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1 SML16012.000-1
Methodology
and AnalysisThe portable
diesel fire pumps would also be staged at higher locations
with hoses stagedthrough higher elevations
of the buildings
to support alternate
RPV makeup.Operators
would be dispatched
with I&C technicians
to the 962' elevation
of the reactor buildingto install the temporary
level indication
per procedure
A.8-05.01.
This would allow for alternate
level indication
to be available
in the event that the batteries
are lost.In the response
scenario
postulated
for the performance
of the operator
manual actions evaluated
in this HRA, EDGs and batteries
are not available.
Shutdown
cooling,
HPCI, and RCIC are notavailable
from normal electrical
means. RCIC is available
for manual operation.
Operators
would have temporary
level indication
set up in the reactor building.
Pressureindication
is available
in the direct area of the level transmitters.
The building
is dark and mostlikely there is water in the basement
of the reactor building.
Additional
portable
lights areavailable
to assist with lighting
and boots staged for higher water. The operators
would utilizeprocedure
A.8-05.01
to un-latch
the governor
from the remote servo linkage and throttle
steamflow to RCIC to start the turbine rolling while coordinating
with operators
monitoring
waterlevel and reactor pressure.
Upon reaching
the high end of the level band the operators
wouldthrottle
closed the steam admission
valve and await direction
to re-start
RCIC. Local operation
of RCIC is demonstrated
each refueling
outage during the over speed test. Operation
of acoupled turbine run is less complex because the turbine is easier to control with a load.3.1.4.2 Detailed
HRAThe human error probabilities
(HEPs) for manual local operation
of RCIC and the Hard PipeVent during an extreme flooding
and SBO event have been developed
in detail utilizing
theEPRI HRA Calculator
(Reference
13). Event RCICSBOFLOOD
(Fail to manually
operateRCIC during SBO and extreme flooding
conditions),
and event HPVSBOFLOOD
(Fail tooperate the HPV using N2 bottles to provide containment
heat removal during SBO/Flood)
havevalues of 9.3E-02 and 1.3 E-02 respectively,
for a combined
value of 1.06E-01.
The HRA Calculator
reports for these events, which provide a detailed
basis for these HEPestimates,
are presented
in Appendix
A. Section A. 1 documents
RCICSBOFLOOD
andSection A.2 documents
HPVSBOFLOOD.
The cognitive
portion of these HEPs was developed
using the Cause Based Decision
TreeMethod (CBDTM) (Reference
13) and the execution
portion utilized
the Technique
for HumanError Rate Prediction
(THERP) (Reference
14). These methods are commonly
used in internalevents PRA, have been cited in the EPRI/NRC-RES
Fire HRA Guidelines,
(Reference
15) and applied in many fire PRAs, and are also cited in the following
reference:
- A Preliminary
Approach
to Human Reliability
Analysis
for External
Events with a Focuson Seismic,
EPRI 1025294,
EPRI, December
2012.NUREG-1921
and THERP are also listed as references
to the following
document:
- Interim Staff Guidance
for Performing
the Integrated
Assessment
for External
Flooding,
Appendix
C: Evaluation
of Manual Actions,
Revision
0, U.S. NRCJapan Lessons-Learned
Project Directorate,
November
30, 2012.Revision
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ISML16012.000-1
Methodology
and AnalysisAppendix
C of the ISG on External
Flooding
concentrates
primarily
on demonstrating
thefeasibility
and reliability
of the manual actions consistent
with NUREG-1852
(Reference
16),"Demonstrating
the Feasibility
and Reliability
of Operator
Manual Actions in Response
to Fire."One of the key variables
in determining
feasibility
of operator
manual actions is timing. Asstated in the ISG, "For an action to be feasible,
the time available
must be greater than the timerequired
when using bounding
values that account for estimation
uncertainty
and humanperformance
variability."
In order to assess this feasibility,
the following
process isrecommended
in section C.3.2.4 Calculate
Time Margin:"The licensee
should calculate
the time margin available
for the action using the values for timeavailable
and time required
that have been developed
for the analysis."
The time margin formula provided
is:[(Tsw-Tdelay)--(Tcog+Texe))
Time Margin = (Tcog.Texe)
X 100%The terms of the equation
are defined as follows:Tdelay = time delay, or the duration
of time it takes for the cue to become available
that indicates
that the action will be necessary
(assumes
that action will not be taken in the absence of a cue);Tsw = the time window within which the action must be performed
to achieve its objective;
Tcog = cognition
time, consisting
of detection,
diagnosis,
and decision-making;
andTexe = execution
time including
travel, collection
of tools, donning of PPE, and manipulation
ofrelevant
equipment.
The HEP calculations
performed
for the RCIC and HPV manual actions involved
the estimation
of the time parameters
cited in the Time Margin formula.
These times are based uponthermal/hydraulics
analyses,
battery depletion
calculations,
several Job Performance
Measure(JPM) exercises
for the specific
proceduralized
actions and considering
flood and SBOconditions,
and discussions
with Operations
and PRA staff.Using this information,
the time margin for these two events is calculated
as:Table 3-5 Time Margin for HFEsTimes (in minutes)
RCIC HPVTsw 478.2 900Tdelay 345 330Tcog 10 10Texe 80 45Time Margin 48% 936%The HEP timing estimates
therefore
meet the criteria
that "using the calculation
under C.3.2.4,the margin must be a positive
percent value for an action to be deemed feasible."
Revision
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1SML16012.000-1
Methodology
and AnalysisThe External
Flooding
ISG also recommends
that estimates
of time available
and time requiredshould account for sources of uncertainty
and human performance
variability.
The timingestimates
shown above are already believed
to be conservative.
For example,
the Tdelay of 345min for the RCIC event is based on 5.75 hours8.680556e-4 days <br />0.0208 hours <br />1.240079e-4 weeks <br />2.85375e-5 months <br /> until RCIC battery depletion.
This can beconsidered
conservative
since, in reality,
it is likely that an action would be taken before waitingfor battery depletion.
For the Texe values, the highest observed
time in the JPM trials was usedfor the RCIC case and further time was added for transit time for actions in various locations.
Forthe HPV case, the Texe value was also based on JPM trial data and the results above show thatuncertainties
are covered by a significant
time margin.In addition
to feasibility,
the reliability
of the actions was evaluated
through the detailed
HRACalculator
analysis
used to quantify
HEPs.Section C4 of the ISG says that for an action to be deemed reliable,
"sufficient
margin shouldexist between the time available
for the action and the time required
to complete
it. This marginshould account for: (1) limitations
of the analysis
(e.g., failure to identify
factors that may delayor complicate
performance
of the manual action);
and (2) the potential
for workload,
timepressure
and stress conditions
to create a non-negligible
likelihood
for errors in taskcompletion...
A simplified
alternative
criterion
for determining
if the margin is adequate
to deeman action as reliable
is to establish
that the margin is not less than 100%. Such a margin may bejustified
when recovery
from an error in performing
the action could be accomplished
byrestarting
the task from the beginning."
As shown above, the time margin for the HPV manual action is greater than 100% and the timemargin for the RCIC manual action is estimated
at around 50%. The evaluation
of PRA andOperations
staff in performing
the JPMs for these actions was that there would be 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> ormore to perform the procedures,
allowing
several opportunities
to troubleshoot
and/or re-perform
steps if necessary.
In addition,
based on the HEP quantification,
the combined
probability
for theRCIC and HPV actions is estimated
to have a success rate of 89%. A sensitivity
study wasperformed
using SPAR-H estimates
to evaluate
the effect of reliability
uncertainty.
Regarding
the evaluation
of factors such as workload
and stress that could complicate
taskperformance,
performance
Shaping Factors (PSFs) were considered
for feasibility
and addressed
in the assessment
of reliability
of the operator
manual actions.The following
table discusses
each of the PSF categories
cited in Appendix
C of the ISG, theissues related to the RCIC and HPV manual actions and how they were addressed
in thequalitative
and quantitative
analysis
of these human failure events.Revision
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1SML16012.000-1
Methodology
and AnalysisTable 3-6 Performance
Shaping Factors for Human Failure EventsPerformance
Shaping Factors Specific
Considerations
for RCIC and HPV Events under SBO and(PSFs) Flooding
Conditions
Cues Cues not only were provided
by the Emergency
Operating
Procedure
flowcharts
for RPV Level and Containment
Pressure
and supporting
procedure,
but would be expected
to be provided
by the Emergency
Response
Organization
staff and STA. It is expected
that daily meetingswould be held to assess the plant situation
considering
the long termeffects of flooding
and SBO and plans would be made to implement
theRCIC and HPV actions.
The decision
to perform these actions wouldtherefore
be made by ERO and STA and the Shift Supervisor
would givethe direction
to operations
staff.Indications
Due to the Station Blackout,
impacts to the normal set of indications
wereexpected
and these effects were implemented
in the CBDTM module ofthe HRA Calculator
consistent
with the methods recommended
inNUREG-1921,
Appendix
B as well as in the Execution
PSFs and Stressmodule. In addition,
the "Degree of Clarity of Cues & Indications"
wasdegraded
from "Very Good" to "Poor".Complexity
of the Required
Action The response
is considered
to be Complex due to the flooding
and SBOimpacts to lighting
and accessibility.
The procedure
steps of the actionsthat are required
and that were evaluated
in the timed Job Performance
Measures
(JPMs) specifically
performed
for these tasks are listed in theExecution
Unrecovered
module of HRA Calculator.
Special Equipment
Flashlights,
headlamps
and boots were considered
necessary
by Trainingwhen the JPMs were performed
for these tasks, and are reflected
in thetiming estimates
for Tm and in the Execution
PSFs Special Requirements
by indicating
that Tools, Parts and Clothing
were required
and available.
Human-System
Interfaces
The interfaces
with the system will be similar,
but with impacts due to theSBO and flooding
in terms of indications
and lighting.
For the RCIC task,a hand-held
reactor level monitor is installed
and used by I&C technicians
to monitor the parameter.
These steps of the procedure
were specifically
included
in the Execution
portion of the RCIC action quantification.
TheHPV task involves
the use of air cylinders
and these steps were alsoincluded
in the Execution
portion of the quantification.
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ISMLI16012.000-1
Methodology
and AnalysisTable 3-6 Performance
Shaping Factors for Human Failure EventsPerformance
Shaping Factors Specific
Considerations
for RCIC and HPV Events under SBO and(PSFs) Flooding
Conditions
Procedures
Multiple
procedures
provide for operation
of the RCIC System without theavailability
of AC or DC power. They address the lighting
and ventilation
limitations
that accompany
a SBO, and provide for alternate
means ofmonitoring
reactor water level/pressure,
controlling
turbine speed,assuring
adequate
water source is available
and accommodating
thecondensate
from the turbine condenser.
- Procedure
8900 (Operation
of RCIC without Electric
Power)* Procedure
C.4-L; Part F (Response
to Security
Threats;
Initiate
Injection
to the RPV with RCIC)* Procedure
A.8-05.01
(Manual Operation
of RCIC)* Procedure
B.08.09-05.H.4
(Condensate
Storage System -FillingCondensate
Storage Tanks from Alternate
Source)-Procedure
A.8-05.05
(Makeup to CST)Any of the following
procedures
provide for operation
of the HPV withoutthe need for normal support systems including
electric
power andpneumatic
supplies.
All necessary
equipment
to perform this function
isspecifically
manufactured
and pre-staged
to allow opening the HPVvalves.-Procedure
B.04.01-05.H.2
(Primary
Containment
System Operation
-Alternate
N2 Supply for Operating
AO-4539 and AO-4540)-Procedure
C.5-3505;
Part A (Venting
VentThrough the Hard Pipe Vent)-Procedure
A.8-05.08
(Manually
Open Containment
Vent Lines)The relevant
procedures
were reviewed,
cues and operator
action stepswere itemized
in the quantification
and were evaluated
using multipleiterations
of the timed JPMs.Training
and Experience
The RCIC and HPV capabilities
are included
in various aspects ofperiodic
operations
training.
Training
materials
and mockup trainingdevices related to these activities
include:" JPM -B.02.03-005
Trip)" Training
mockup of the RCIC Turbine Trip Throttle
Valve (MO-2080)
" Lesson Plan MT-ILT-EOP-002L
(RPV Control)" Lesson Plan MT-NLO-12C-002L
(Emergency
Operating
Procedures
Overview)
- Lesson Plan MT-NLO-EOP-001
Building))
- Lesson Plan MT-OPS-FB-004L
(Level 4 -Extensive
Damage Mitigation
Guidelines)
-Lesson Plan M-8107L-003
(RCIC)Additionally,
control of RCIC, using the RCIC MO-2080 Turbine TripThrottle
Valve is actually
performed
during the startup from each refueling
outage, in the performance
of procedure
1056 (RCICI Turbine Overspeed
Trip Test).Operator
training,
procedure
adequacy,
and equipment
readiness
regarding
use of these mitigation
measures
has been reviewed
by theNRC as part of the B.5.b and Fukushima
Flex response
inspections
andbeen determined
to be acceptable.
- ML1 1235A897
(NRC Fire/B.5.b
Inspection
Report; 8/23/11)* ML1 11320400
(NRC Temporary
Instruction
2515/183;
5/13/11).
Perceived
Workload,
Pressure
Under the quantification
Execution
PSFs, Workload
has been assessedand Stress as High and PSFs of Negative,
so the overall stress is assessed
as High.Revision
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ISMLI16012.000-1
Methodology
and AnalysisTable 3-6 Performance
Shaping Factors for Human Failure EventsPerformance
Shaping Factors Specific
Considerations
for RCIC and HPV Events under SBO and(PSFs) Flooding
Conditions
Environmental
Factors The environment
would be consistent
with SBO (hot, dark, damp) andsome Reactor Building
flooding
requiring
boots. These were theconditions
evaluated
during the timed JPMs and are addressed
in thequantification
under Execution
PSFs for Lighting,
Heat/Humidity
andAtmosphere.
Special Fitness Issues No special fitness issues were identified
although
the performance
ofmultiple
trials of the JPMs is considered
to address the variability
inpersonnel
fitness.Staffing
Operations
staffing
to perform the procedures
would be optimal (severaloperators
assigned
as desired to each procedure).
Discussions
were heldto evaluate
whether there would be dependencies
in staffing
between theRCIC and HPV actions and it was considered
that due to the different
timeframes,
that the actions and staffing
would be separate.
Communications
Under SBO conditions
the use of radio and walkie talkies would beexpected
to allow communications
to be maintained
between the MainControl Room and the I&C Technicians
and the staff performing
the keyactions.Accessibility
The Equipment
Accessibility
is evaluated
as "With Difficulty"
due toreactor building
lighting
and flooding
issues. The quantification
Execution
PSFs indicates
this and these issues were addressed
during the JPMtiming sessions.
A sensitivity
analysis
was also performed
by developing
human error probabilities
(HEPs) formanual local operation
of RCIC and the Hard Pipe Vent during an extreme flooding
and SBOevent utilizing
the SPAR-H module of the EPRI HRA Calculator
and recommended
practices
from the Idaho National
Laboratory
step-by-step
SPAR-H guidance
(Reference
17). UsingSPAR-H, event RCICSBOFLOOD
(Fail to manually
operate RCIC during SBO and extremeflooding
conditions),
and event HPVSBO FLOOD (Fail to operate the HPV using N2 bottles toprovide containment
heat removal during SBO/Flood)
have values of 1.4E-01 and 5.5E-02respectively,
for a combined
value of 1.95E-01.
The HRA calculator
reports associated
with these HEPs can be found in sections
A.3 and A.4 ofAppendix
A.Revision
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ISML16012.000-1
Conclusions
4.0 CONCLUSIONS
The results of the analysis
are shown in Table 4-1. This table includes
the results of both the bestestimate
quantification
and the sensitivities
that were performed
in support of this analysis.
The ACDF represents
the difference
between the best-estimate
CDF and the baseline
CDF. Thebaseline
CDF is the CDF without the performance
deficiency.
The best-estimate
CDF is theresult of the event tree calculations
shown in Appendix
A. The exposure
time represents
theperiod of time the plant was exposed to the performance
deficiency.
This time period was fromFebruary
29, 2012 to February,
15, 2013 resulting
in an exposure
time of 352 days or 0.964years. The failure to build construct
a levee is assumed to be 0.11 (consistent
with theprobability
assumed by the NRC). Therefore,
the baseline
CDF is calculated
by multiplying
thebest-estimate
CDF by 0.11. ACDF is equal to the best-estimate
minus the baseline,
thus:= best-estimate
-0.11 x best-estimate
= (1-0.11)
x best-estimate
= 0.89 x best-estimate.
ACDP = exposure
x ACDF = 0.964 x 0.89 x best-estimate.
Table 4-1 Results of Event Tree Quantification
Sensitivity
1: Sensitivity
2:NRC Case Nominal,
Bounding
Flood SPAR-H HRAFrequency
Probabilities
CD Seq 1 8.41 E-07 1.06E-06
1.55E-06CD Seq 2 9.15E-08
9.43E-07
1.68E-07CD Seq 3 1.07E-07
1.10E-06
1.07E-07CDF 4.20E-05
1.04E-06
3.10E-06
1.83E-06ACDF 3.60E-05
8.92E-07
2.66E-06
1.57E-06Significance
Yellow Green White WhiteThe results of this analysis
show that by a best-estimate
analysis,
the significance
of the floodingevent is Green. Two sensitivity
studies performed
to evaluate
the effects of sources ofuncertainty
show that the significance
of the flooding
could be characterized
as low to moderatesafety or security
significance
or 'White' using bounding
assumptions.
Revision
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2Page 15
I SML16012.000-1
Appendices
APPENDICES
TABLE OF CONTENTSA. APPENDIX
A -HRA CALCULATOR
REPORTS ........................................
A-1A.1. RCICSBOFLOOD,
Fail to manually
operate RCIC during SBO andextrem e flooding
conditions
...............................................................
A-1A.2. HPVSBOFLOOD,
Fail to operate the HPV using N2 bottles to providecontainment
heat removal during SBO/Flood
.......................................
A-19A.3. RCICSBOFLOOD,
Fail to manually
operate RCIC during SBO andextreme flooding
conditions
(SPAR-H)
.................................................
A-31A.4. HPVSBOFLOOD,
Fail to operate the HPV using N2 bottles to providecontainment
heat removal during SBO/Flood
(SPAR-H)
......................
A-36B. APPENDIX
B -EVENT TREES ...................................................................
B-1Revision
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1SML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSA. APPENDIX
A -HRA CALCULATOR
REPORTSThe following
sections
document
the HRA Calculator
reports that support this analysis.
A.1. RCIC_SBOFLOOD,
Fail to manually
operate RCIC during SBO and extremeflooding
conditions
Basic Event Summary.%Plant Data File: ':FiledSize'
File Dated. IR1ecord.
DateMonticello
Ext 913408 07/02/13
07/02/13Flooding
SDPHRAJune2013.HRA':Nam ;-DateAnalyst Erin P. Collins,
Hughes 07/02/2013
Associates
Reviewer
John Spaargaren
& Pierre 07/02/2013
Macheret,
Hug hes Associates
Table 41: RCIC_SBOFLOOD
SUMMARY______________
~HEP,-Sumay
__Pcog Pexe Total HEP ErrorFactorMethod CBDTM THERP CBDTM + THERPWithout Recovery
2.9e-02 5.2e-01With Recovery
9.2e-04 9.2e-02 9.3e-02 5Initial Cue:RPV Water Level Below 9 in.Recovery
Cue:Before RPV level drops to -149 inchesCue Comments:
The cue for action is that the TSC and the Emergency
Director
have determined
that RCIC operation
isneeded. The Control Room Supervisor
(CRS) directs operator
to initiate
RCIC and inject into the RPVusing procedure
A.8-05.01,
Manual Operation
of RCIC, Part A, Placing RCIC in Service.Due to the SBO, it is assumed that there will be multiple
impacts to indications,
so the degree of clarityhas been set at "Poor".Deqree of Clarity of Cues & Indications:
PoorProcedures:
Cognitive:
C.5-1 100 (RPV CONTROL flowchart
(Monticello))
Revision:
11Execution:
A.8-05.01
(Manual Operation
of RCIC) Revision:
2Other: A.6 (ACTS OF NATURE (Monticello))
Revision:
43Other: 8900 (OPERATION
OF RCIC WITHOUT ELECTRIC
POWER (Monticello))
Revision:
2Revision
2 Page A-IRevision
2Page A-1
1SML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSCognitive
Procedure:
Step: LEVELInstruction:
Restore and maintain
RPV water level 9 to 48 in. using Preferred
Injection
SystemsProcedure
and Training
Notes:Three JPM trials were performed
emulating
the specific
external
flooding
conditions
of this scenario
on 18June 2013. Observations
were factored
into this analysis.
Procedure
A.8-05.01
-2.0 ENTRY CONDITIONS
This strategy
is entered when one or more of the following
conditions
are met:o As directed
from A.8-01.01
(Extensive
Damage Mitigation
Strategy
Overview)
o As directed
from A.8-03.01
(Initial
Response
Actions)o As directed
from 5790-110-01
(Monticello
Emergency
Management
Guideline)
-presume this is therelevant
case since ERF is staffed and will make the call on implementing
the procedure
Training:
Classroom,
Frequency:
0.5 per yearSimulator,
Frequency:
0.5 per yearJPM Procedure:
JPM-A.8-05-01-001
(Manual Operation
of RCIC) Revision:
0Identification
and Definition:
1. Letter to Region III SRA write-up,
8 April 2013Section G -HEP Associated
with Protecting
Plant Buildings
from 930' Elevation
FloodFor the case where the site is not protected
by a ring levee, but individual
buildings
/ equipment
areprotected
by flood barriers
as called out in the A.6 (Acts of Nature) procedure,
several redundant
optionsremain available
for protecting
critical
safety functions
related to injecting
water to the reactor,
maintaining
desired reactor pressure,
and removing
decay heat from containment.
The A.6 Procedure
[Acts of Nature that addresses
External
Flooding]
directs de-energizing
the 115 KV,230 KV and 345 KV substations
for flood levels in excess of the 930' elevation.
In the case where theflood level is above 930' this would lead to a loss of offsite power and reliance
on the EDGs. Since thenormal long term fuel oil storage (Tank T-44) for the EDG's is not evaluated
to survive flood levels above932' elevation,
and alternate
fuel oil makeup methods are not pre-prescribed
to support the EDG's, longterm EDG operation
is not easily defensible.
Additionally,
there are several penetrations
in the PlantAdministration
Building
that would make positive
flood proofing
of the building
difficult,
leaving three of thefour station batteries
vulnerable
to flooding.
2. PRA-MT-SY-RCIC,
Reactor Core Isolation
Cooling System Notebook,
Revision
3.0, December2012Table 3 -IE_LOOP (Loss Of Offsite Power Initiating
Event) Impact on RCIC System: A loss-of-offsite
power does not affect RCIC, provided
AC power remains available
to the Division
1 battery chargers.
Aloss of Feedwater
would result, and RCIC operation
would be automatically
actuated
when Low-LowLevel in the RPV is reached.Key Assumptions:
It is assumed that there will be sufficient
water and fuel supply for the equipment
needed in this scenariodespite the flooding
conditions
and considering
the long term nature of the flood, which may take as manyas 12 days to recede (from the Monticello
Design Basis documentation).
This means that CST level is assumed to be maintained
via a step in this HEP and is not quantified
separately.
Another key assumption
is that because the staffing
needed for this event is separate
from that used forthe Hard Pipe Vent human failure event, and the timeframe
for HPV is much longer, no dependency
between these events was evaluated
(in other words, the timing and staffing
were considered
as totallyseparate
events).Revision
2Page A-2
1SMIL160112.000-11
Appendix
A -HRA CALCULATOR
REPORTSISM LI 6012.000-1
Appendix
A -HRA CALCULATOR
REPORTSJPM-A.8-05.01-001
(Manual Operation
of RCIC) Rev. 0INITIAL CONDITIONS:
o Extreme flooding
has led to a Station Blackout
that has existed at Monticello
for the last 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />.o Div. 1 250 VDC battery system has been depleted
and is not available.
o The plant was in Shutdown
Cooling until the station blackout
and has since been slowlyrepressurizing
due to heating up.o Current RPV pressure
is 75 psig-and
slowly rising.o Current RPV water level is -40" and very slowly lowering.
o The TSC and the Emergency
Director
have determined
that RCIC operation
is needed.o HPCI is inoperable.
o RCIC suction is from the CSTs.o RCIC operation
is required
to maintain
RPV level above TAF.o Approximately
2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> ago Radiation
Protection
reported
-2" of water on the Rx Bldg basementfloor.o A second operator
will be performing
Part B, Set Up and Monitor of Rx Vessel with Fluke 707.o A third operator
will be maintaining
CST level using A.8-05.05,
Makeup to the CST, and verifying
valve status in the steam chase.INITIATING
CUES (IF APPLICABLE):
o The CRS directs you to initiate
RCIC and inject into the RPV using A.8-05.01,
Manual Operation
ofRCIC, Part A, Placing RCIC in Service.o Inform the CRS when RCIC is in service with discharge
pressure
at least 76 psig greater than reactorpressure..
RCIC local manual operation
Job Performance
Measure entry condition
assumptions,
Documented
in andexcerpted
from Hughes Associates
Record of Correspondence,
RCIC Manual Operation
e-mails with XcelEnergy during June -July 2013, Hughes Associates,
Baltimore,
MD, 7 July 2013:Conditions
anticipated
following
a SBO resulting
from an external
flooding
event:o ERO has been manned for the past several days, with these procedures
predicted
and plannedto be implemented
ahead of timeo Plant is in cold shutdown
condition
(mode 4)o I&C would perform the reactor level monitoring
portion of the RCIC procedure
o Operations
staffing
to perform the procedures
would be optimal (several
operators
assigned
asdesired to each procedure)
o Environment
would be consistent
with SBO (hot, dark, damp)o There would be 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> to perform the procedures,
allowing
several opportunities
to troubleshoot
and/or re-perform
steps if necessary
o The ERO would place maximum priority
on maximizing
chances of successful
performance
ofthese procedures
Operator
Interview
Insights:
Documented
in and excerpted
from Hughes Associates
Record of Correspondence,
RCIC ManualOperation
e-mails with Xcel Energy during June -July 2013, Hughes Associates,
Baltimore,
MD, 7 July2013:From Xcel Operations:
The series of events would progress
during a flooding
event such that the need forthe alternate
instrumentation
would be known before the flood completely
resulted
in a station blackoutwith loss of DC. The alternate
instrumentation
(Fluke) would be connected
to the selected
locations.
Ifthis instrumentation
did not agree with the actual permanent
instrumentation
(i.e. prior to failure),
assistance
would be obtained
to figure out the discrepancy.
It is a relatively
simple solution
to get thetemporary
instrumentation
to work by either pulling a fuse or lifting a lead. This action would be requiredRevision
2Page A-3
I SMLI16012,000-1
Appendix
A -HRA CALCULATOR
REPORTSfor the control room, cable spreading
room and EFT locations
(again not proceduralized).
The otheroption would be to use the transmitter
in the reactor building
to get the readings
which does not requirethe lifted lead or fuse pulled.The other issue that is of concern is the need to density compensate
the fluke readings
to get an actuallevel. The indicated
level can be drastically
different
from the actual level depending
on the calibration
conditions
of the instrument
(hot or cold calibration
conditions)
and the actual pressure/temperature
at thetime of the reading.
None of this information
is contained
in the A.8 procedures.
There are densitycompensation
tables in the B.1.1 operations
manual figures section six and they are also posted in thecontrol room. It would take additional
action for the on-shift
team/technical
staff to put this all together
todetermine
what actual level was from the readings
that came off the fluke.
FD "nniramanta
el
=~ :!.n cluded. Total Available
Reuired for PNotes________.......___....
..__ ... ... __ .... .. .._____ Execuition
_________________i
Reactor operators
Yes 2 1Plant operators
Yes 2 0Mechanics
Yes 2 0Electricians
Yes 2 0I&C Technicians
Yes 2 0Health Physics Technicians
Yes 2 0Chemistry
Technicians
Yes 1 0Execution
Performance
Shapina Factors:Environment:
Lighting
PortableHeat/Humidity
Hot / HumidRadiation
Background
Atmosphere
Steam (although
steam will notbe present,
this PSF was usedto indicate
an off-nominal
condition,
such as would bepresent for flood and SBO)Special Requirements:
Tools RequiredAdequateAvailable
Parts RequiredAdequateClothing
RequiredAdequateComplexity
of Response:
Cognitive
ComplexExecution
ComplexEquipment
Accessibility
Main Control Room Accessible
(Cognitive):
Equipment
Accessibility
Reactor Building
With Difficulty
(Execution):
Stress: HighPlant Response
As Expected:
YesWorkload:
HighI Performance
Shaping Factors:
NegativeRevision
2Page A-4
ISML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSPerformance
Shaping Factor Notes:The response
is considered
to be Complex due to the flooding
and SBO impacts to lighting
andaccessibility.
Flashlights,
headlamps
and boots were considered
necessary
by Training
when the JPMswere performed
for these tasks.The Equipment
Accessibility
is evaluated
as With Difficulty
due to Rx building
lighting
and flooding
issues.Despite preparations
and training,
the flooding
scenario
is considered
to be a high stress situation.
Key Assumptions
(see that section)
regarding
the conditions
provided
to Training
for performing
the JPMfor this task said that the "Environment
would be consistent
with SBO (hot, dark, damp)". The Traininginsights
from the JPM performance
(see Operator
Interview
Insights)
stated that the operators
recommended
to "Stage additional
flashlights
and headlamps
in RCIC room", so it is clear that portablelighting
is used.Revision
2 Page A-5Revision
2Page A-5
1 SML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSTiming:T S 7.97 HoursT dly5.75 Hours T / 10.00 Minutes T M 80.00 MinutesIrreversible
Cue DamageState
t=oTimingi Analysis:
TO = Station BlackoutTsw = Time from Station Blackout
to the time by which RCIC must be restored.
Per Monticello
MAAP Calculations,
case "SBOCase3-R1",
27 June 2013:Time to TAF = 7.17 hrsTime to -149" = 7.2 hrsTime to 1800 F = 7.97 hrsDamage is assumed to occur if the temperature
exceeds 1800 F or 7.97 hrs, so this was used for Tsw asthe time by which RCIC restoration
is required.
Tdelay = PRA battery calc (PRA-CALC-1
1-002) indicates
that there are 5.75 hrs until RCIC batterydepletion.
Also, the RCIC Water Flow (column BC) of the d41 tabs in the "SBOCase3-R1"
MAAPanalysis
spreadsheet
shows that RCIC injection
stops at approximately
the same time (5.74 hrs), so theMAAP runs agree with the calc. This Tdelay can be considered
somewhat
conservative,
since in reality,
itis likely that an action would be taken before waiting for battery depletion.
T1/2 = The cue for action is that the TSC and the Emergency
Response
Director
have determined
thatRCIC operation
is needed. Daily planning
meetings
will have been held to discuss actions to be taken assoon as the diesels are lost, so the 10 minutes is simply an estimate
of the meeting time between TSCand ERF personnel
to make the actual decision
to manually
operate RCIC. The Control Room Supervisor
(CRS) directs operator
to initiate
RCIC and inject into the RPV using procedure
A.8-05.01,
ManualOperation
of RCIC, Part A, Placing RCIC in Service.Tm = Results of RCIC local manual operation
Job Performance
Measure performed
18 June 2013. Theprocedure
was performed
three times, taking 49 minutes,
37 minutes and 50 minutes to complete
for anaverage time of 45 minutes.
50 minutes was used as the conservative
value for JPM performance.
The JPM did not include the performance
of Part B for installation
and use of the Fluke level monitoring
device; this was estimated
to require 30 minutes,
so the total time for Tm was estimated
as 50 min + 30min = 80 min.Time available
for cognition
and recovery:
53.20 MinutesTime available
for recovery:
43.20 MinutesSPAR-H Available
time (cognitive):
53.20 MinutesRevision
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2Page A-6
1SML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSI SMLI 6012.000-1
Appendix
A -HRA CALCULATOR
REPORTSSPAR-H Available
time (execution)
ratio: 1.54Minimum level of dependence
for recovery:
LDRevision
2 Page A-7Revision
2Page A-7
1SML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSI SMII 6012.000-1
Appendix
A -HRA CALCULATOR
REPORTSCognitive
Unrecovered
RCICSBOFLOOD
Table 42: RCICSBOFLOOD
COGNITIVE
UNRECOVERED
Pc Failure Mechanism;.
Birainch
'HEPPca: Availability
of Information
d 1.5e-03PCb: Failure of Attention
m 1.5e-02Pcc: Misread/miscommunicate
data e 3.0e-03Pcd: Information
misleading
b 3.0e-03Pce: Skip a step in procedure
9 6.0e-03Pcf: Misinterpret
instruction
a neg.Pcg: Misinterpret
decision
logic k neg.PCh: Deliberate
violation
a neg.Sum of Pca through PCh = Initial Pc = 2.9e-02Notes:Normal RPV water level indication
is not available
and must be monitored
with a hand held deviceinstalled
by I&C. This is clearly proceduralized
in Part B of A.8-05.01.
Presumed
that SBO causes issues with normal alarms and indications
so pc-a through -d were adjustedconsistent
with insights
from EPRI 1025294,
A Preliminary
Approach
to Human Reliability
Analysis
forExternal
Events with a Focus on Seismic,
October 2012.Revision
2 Page A-8Revision
2Page A-8
I SM L16012.000-11
Appendix
A -HRA CALCULATOR
REPORTSISM LI 6012.000-1
Appendix
A -NRA CALCULATOR
REPORTSpca: Avalabilty
of infonnation
u ,cation Aal in CR Inicalion
WaIingAlternate
'l'kaining
onCR Accurate
W Procedure
Infelators
Yes(a) neg.(b) neg.(c) neg.3.-e-03 -(d) 1.5e-0311.0e+001.0e-01 (e) 5.0e-021.0e+00 (f) 5.0e-011.0e400(g) I.0e+O01LOO1MMCR indications
may not be accurate
due to the Station Blackout,
however,
either procedural
or informalcrew information
on alternate
indications
and training
should provide operator
input to decision-making.
pcb: Falum of attention
Low vs. M Check vs. Monitor Front vs. Back Alaued vmNotWorkload
Pan el Alnnedek IO O(a) neg..e*i Back I 0(b) .5e-043.0e-0 (c) 3.0e-031.8e+.00
Front 15.0e-02
(d) I.5e-04io.00M oI (e) 3.0e-033e-03 Back 15.0e-02
(f) 3.0e-041. Cb ie 3.0e-03 (g) 6.Oe-032. Cb ice Front 15.0e-02
((h) neg.Check O.e00 e4 (i)neg.o.oeo Back 5.0e,.2 (i) 7.Se-04lh 3.0e-03 (k) 15e-02Front -(I)7.e-04
Monito r O.O+- WL -- (m) I.5e-023.e35 I50e-02 (n) 1.5e-033.0e-3 I (o) 3.Oe-021.0e4.0Revision
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2Page 9
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Appendix
A -HRA CALCULATOR
REPORTSISM LI 6012.000-1
Appendix
A -HRA CALCULATOR
REPORTSpcc nicate dataIhucatom
Easy to Good&Bad
Inicator
FoanalLocateI CoImunKicaUons
S O.e 4.0 0 (a) neg.S3.0e-033.e-03
0.Oe+00 I (c) I.Oe-03YeIot.0e-0
A(d) 4.0e-033.0e-03No ---o (e) 3.0e03o.oe*Coo
(6e33F)03 6.e-03L 3Oe-033.OeO3 (g) 4.0e-031.0e-03 (3.Oe-03(h)
7.Oe-033.0e-03For this scenario,
normal reactor water level indication
is not available
and a hand-held
level monitor willbe jumpered
in. Although
procedural
guidance
on reading the monitor is clear, "not Easy" is selected
toreflect the additional
challenges
to the task posed by this alternative
source for level indication.
pcd: Infoonation
mismeming
M Cues as Stated mring of Specicr ,Rang I General Ta-anugI ~ ~Ifferences
IIo.oesoo (a) neg.No---- -- -- ----- --- --- ----- --- ----- --- (b) 3.e-031.0e+O0 (c) 1.0e-021.0e-02MCR indications
may not be accurate
due to the Station Blackout
so cues may not be as stated inprocedures.
pce: Sip a step in procedure
Obqgiousv&
Singl vs. NfUN*l Graphicaly
Placekeqing
Ad(a) 3.0e-033.3"1 (b) 3.0e-03()e-02o.Oe+O 13.0e-03
(c) 3.0e-03130e0eO0I
(e) 2.0e-03(h) 1.3e-02---------------------------
(g) .oe-o31.0e-021.0e-4D 1 01) t.Oe -01Revision
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Appendix
A -HRA CALCULATOR
REPORTSISM LI 6012.000-1
Appendix
A -HRA CALCULATOR
REPORTSpd' Misinterpret
instruction
Standard
or AN Required
Training
on StepAmbiguous
wording Information
I--- ------ ------- ------- ------- (a) neg.(b) 3.0e-033.0e-02 (:c) 3.0e-02Yes 1.0e4.00NO1.0e,4
(d) 3.0e-030.0e+00 (e) 3.0e-023.0e-02 1(f) 6.0e-033.0e-02 (g) 6.0e-02pcg: Misinterprt
decision
ogic"NOr Statement
'ANUD or 'Or Both "AND" & practiced
ScenarioStatement
"OW3-le0M (a) 1.6e-023.0e.02 I(b) 4.9e-021.2e-02 (c) 6.0e-030o.oe+oo
l(d) 1.9-02(e) 2.0e-03O.Oe.+O0
(t) 6.0e-03Yes 3~e-. (g) 1.0e-02NO 3.0e..02
-(h) 3.1e-02.0e4.001.0e-03 (I) 3.0e-04---O.OeO Fi) 1.0e-030.0e+00 l .0e44)3.----- (k) neg.O.Oe.F (1) neg-pch: Delbe ate Wiolation
BEleinAdequacy
Advere Reasonable
Polcy ofof Instruction
Consequenceff
Alternatives
"Vembatin"
-.---- ------- --- ------- ------- ------- --- --(a)neg.Ye15.0e-
(b) 5.oe-o1NO.e00 I.OeO (c) I.Oe-Oo1.0e+00 I O.Oe+O0 (d)neg.0.0e44)0
(e) neg.Revision
2 Page 11Revision
2Page11
1SML-16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSI SMLI 6012.000-1
Appendix
A -HRA CALCULATOR
REPORTSCognitive
RecoveryRCICSBOFLOOD
Table 43: RCICSBOFLOOD
COGNITIVE
RECOVERYU- ', a_ , .E -FinalInitial HEP FinalS0) W C ValueLU OOr "(LU >S o n- -ý.'PCa: 1.5e-03 X -5.0e-01 7.5e-04Pcb: 1.5e-02 X -X X MD 3.8e-03 5.7e-05Pcc:: 3.0e-03 --X X -1.0e-02 3.0e-05Pcd! 3.0e-03 -X X X -5.0e-03 1.5e-05Pce: 6.0e-03 X X X MD 1. le-02 6.6e-05Pof, nell. -1.0e+00Pc-:. neg.- -1.0e+00Pch: : ne .-1.0e+00Sumof
Pch = Inita Pc-= 9.2e-04Notes:Due to long timeframe
and severity
of scenario,
STA and Emergency
Response
Facility
will be available.
Operations
staffing
to perform the procedures
was assessed
by Xcel as optimal (several
operators
assigned
as desired to each procedure)
so Extra Crew was credited.
Used Moderate
Dependency
due to high stress.Revision
2 Page 12Revision
2Page 12
ISML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSISM LI 6012.000-1
Appendix
A -HRA CALCULATOR
REPORTSExecution
Unrecovered
RCICSBOFLOOD
Table 44: RCICSBOFLOOD
EXECUTION
UNRECOVERED
Procedure:
A.8-05.01,
Manual Operation
of RCIC .Comment.
Stress- Over Ride%* .- ,.FactorStep No. instrUction/Comment
Error ..THERP -HEP... ..* .....YPe.. .. 1. Table .. I .*Item * __._ * ._.In RCIC Room, verify open valves MO-2106 and MO-2096 Depress declutch
lever and turn handwheel.
A.8-05.01,
Step 8 Location:
Reactor Building
EOM 20-7b 2 1.3e-03 5EOC 20-13 1 1.3E-3Total Step HEP 1.3e-02Remove the pin securing
the slip link to the governor
lever to preventinterference
from the hydraulic
governor
(See Attachment
1) 5A.8-05.01,
Step 9 Location:
Reactor Building
EOM 20-7b 2 1.3e-03EOC 99 1 1.OE-2Total Step HEP 5.7e-02Uncap and throttle
open RCIC-27 condenser
cooling water starting
YSA.8-05.01,
Step 20 6082 drain. Close when steam is present.
5-22 Location:
Reactor Building
EOM 20-7b 2 1.5e-03_5
-_22_EOC
20-12 5 1.3E-3Total Step HEP 1.3e-02Throttle
MO-2080 and control as necessary
A.8-05.01
Steps Location:
Reactor Building
EOM 20-7b 2 1.3e-03 517,18,25,26
EOC 20-12 5 1.3E-3Total Step HEP 1.3e-02At D31, Access Control -SET UP for Monitoring
RX Vessel level byA.8-05-01,
Step 2, opening circuits
and kick out to Part B Mat D31 Location:
Reactor Building
EOM 20-7b 3 1.3e-03_5
atD31_EOC
20-12 3 1.3E-3Total Step HEP 1.3e-02At D100, 1st Floor EFT -SET UP for Monitoring
RX Vessel level byA.8-05-01,
Step 2, opening circuits
and kick out to Part BAt ST Location:
EFT EOM 20-7b 3 1 .3e-03At EFT EOC 20-12 3 1.3E-3Total Step HEP 1.3e-02SET UP for Monitoring
RX Vessel level by selecting
level instrument
and PART B SET UP AND MONITOR OF RX VESSELattaching
Fluke 707 monitoring
device -Control Room WITH FLUKE 707Part B, Steps 29 & 29. SELECT a level instrument
from list below,30P -MCR (preference
should be given to accessibility
and 5environmental
conditions
such as radiation,
temperature,
lighting,
etc.):In Control Room;Revision
2Page A-1 3
ISML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSSýProcedure:'A.8.45.01;
Manual Operationof.RCIC
Comment Stress. Over RideFactorStep No. Instruction/Commetn:t-:
Error THERP HEPi. " .i : .... ..... ..-" ' i , " : i :+ Tabley. ; I;. , tem ... .I. .LI-2-3-85A,
Reactor Vessel Water Level, Panel C-03, Term Strip TT-62 to TT-61.LI-2-3-85B,
Reactor Vessel Water Level, Panel C-03, Term Strip PP-70 to PP-71.LI-2-3-91A,
Fuel Zone, Panel C-03, Term Strip TT-59 to TT-58.30.
If Level Indicator
selected
for use,Then ATTACH one lead from Fluke 707 to eachterminal
point listed.Location:
Main Control Room EOM 20-7b 3 1.3e-03EOC 20-12 13 1.3E-2Total Step HEP 7.2e-02SET UP for Monitoring
RX Vessel level by selecting
level instrument
and PART B SET UP AND MONITOR OF RX VESSELattaching
Fluke 707 monitoring
device -Cable Spreading
Room WITH FLUKE 70729. SELECT a level instrument
from list below,(preference
should be given to accessibility
andenvironmental
conditions
such as radiation,
temperature,
lighting,
etc.):In Cable Spreading
Room;Part B, Steps 29.& LI-2-3-91A,
Fuel Zone, Panel C-18, Term Strip BB- 530 -CSR 57 to BB-59.If Level Indicator
selected
for use,Then ATTACH one lead from Fluke 707 to eachterminal
point listed.Location:
Cable Spreading
Room EOM 20-7b 3 1.3e-03EOC 20-12 13 1.3E-2Total Step HEP 7.2e-02SET UP for Monitoring
RX Vessel level by selecting
level instrument
and PART B SET UP AND MONITOR OF RX VESSELattaching
Fluke 707 monitoring
device -EFT WITH FLUKE 70729. SELECT a level instrument
from list below,(preference
should be given to accessibility
andenvironmental
conditions
such as radiation,
temperature,
lighting,
etc.):At 3rd Floor EFT, ASDS Panel;LI-2-3-86,
Reactor Flooding
Level, Panel C-292,Part B, Steps 29 & Term Strip (EFT 3) HH-4 to HH-5. 530 -EFT LI-2-3-91
B, Fuel Zone, Panel C-292, Term Strip(EFT 3) HH-1 to HH-2.If Level Indicator
selected
for use,Then ATTACH one lead from Fluke 707 to eachterminal
point listed.Location:
EFT EOM 20-7b 3 1.3e-03EOC 20-12 13 1.3E-2 IRevision
2Page A-14
1SML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSI SMLI 6012.000-1
Appendix
A -HRA CALCULATOR
REPORTSProcedure:
A.8-05.01,
ManUal Operation
of R(Step No.instruction/Cot
SET UP for Monitoring
RX Vessel level by selecting
level instrument
andattaching
Fluke 707 monitoring
device -Reactor BuildingPART B SET UP AND MONITOR OF RX VESSELWITH FLUKE 70729. SELECT a level instrument
from list below,(preference
should be given to accessibility
andenvironmental
conditions
such as radiation,
temperature,
lighting,
etc.):At 962', Rx Bldg;LT-2-3-85A,
Reactor Vessel Water Level, Panel C-56.LT-2-3-85B,
Reactor Vessel Water Level, Panel C-55.LT-2-3-61,
Reactor Flooding
Level, Panel C-55.At 935', Rx Bldg;LT-2-3-112A,
Fuel Zone, Rx Bldg 935' West, PanelC-122.LT-2-3-112B,
Fuel Zone, Rx Bldg 935' East, PanelC-121.31. If level transmitter
selected
for use,Then PERFORM the following:
a. REMOVE the cover (see Attachment
5 & 6).b. LIFT positive
lead from its conductor
(seeAttachment
7).c. Slightly
ENGAGE screw threads into transmitter.
d. CLAMP Fluke 707 leads in series with liftedpositive
wire and positive
terminal
point ontransmitter.
Part B, Steps 29 &31 -RxB5Location:
Reactor Building
EOM 20-7b 3 1 .3e-03EOC 1 20-12 1 13 1 1.3E-2-t --Total Step HEP 7.2e-02MONITOR OF RX VESSEL WITH FLUKE 707 (Conducted
separately
by DETERMINE
Rx water level by performing
theI&C) following:
(see Attachment
8 -diagram of FLUKE 707CALIBRATOR
pointing
out buttons and displays)
a. PRESS green button to START Fluke 707.b. PRESS MODE button until display readsMEASURE mA and Loop Power.c. USE Attachment
9 to obtain vessel level. [readPart B, Step 32 table of RCIC -mA VS. RPV WATER LEVEL]33. If connected
to LT-2-3-61
or LI-2-3-86,
Then OPERATE RCIC turbine to maintain
steadyindication
as close to 8 mA aspossible.
34. If NOT connected
to LT-2-3-61
or LI-2-3-86,
Then OPERATE RCIC turbine to maintain
steadyindication
as close to 20 mA aspossible.
Revision
2 Page A-15Revision
2Page A-1 5
1SML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSProcedure:-A.8-05.01,
Manual Operation
of RCIC Comment-w
.'Stress Over Ride,FactorStep INo .Instrudtion/comnment.
Error -~ THERP :F HEP.Typeý. Table,. ItemLocation:
Reactor Building
EOM 20-7b 3 1.3e-03EOC 20-11 1 1.3E-3Total Step HEP 1.3e-02Interpret
Fluke monitor readings
using density compensation
tables in E-mail from Xcel Operations
toB.1.1 operations
manual, section 6 (posted in Control Room) Xcel PRA Manager,
2 July 2013The indicated
level can be drastically
different
fromthe actual level depending
on the calibration
conditions
of the instrument
(hot or cold calibration
conditions)
and the actual pressure/temperature
atthe time of the reading.
None of this information
iscontained
in the A.8 procedures.
There are density 5Part B, Step 32c compensation
tables in the B.1.1 operations
manualfigures section six and they are also posted in thecontrol room. It would take additional
action for theon-shift
team/technical
staff to put this all together
todetermine
what actual level was from the readingsthat came off the fluke.Location:
Main Control Room EOM I 20-7b 3 1.3e-03EOC 120-10 10 1.3E-2Total Step HEP 7.2e-02Maintain
CST level and venfy valve status in the steam chase ILocation:
Reactor Building
EOM 20-7b 4 4.3e-03 5EOC 20-12 5 1.3E-3Total Step HEP 2.8e-02Feedback
from I&C Level Monitoring
i 5Recovery
1 Location:
Reactor Building
EOM 99 1 1.0e-02Total Step HEP 5.0e-02Feedback
from Control Room 1 5Recovery
2 Location:
Main Control Room EOM 20-7b .3 1 1.3e-03Total Step HEP 6.5e-03Revision
2Page A-1 6
1SML-16012,000-1
Appendix
A -HRA CALCULATOR
REPORTSI SMLI 6012.000-1
Appendix
A -HRA CALCULATOR
REPORTSExecution
RecoveryRCICSBOFLOOD
Table 4-5: RCICSBOFLOOD
EXECUTION
RECOVERYCritical
Step No.Recovery
Step No.ActionHEP (Crit)HEP (Rec).Dep. Cond. HEP Total forDe. (Recl Stan,A-8-05.01,
Step 8 In RCIC Room, verify open valves MO-2106 and MO-2096 1.3e-02 7.3e-04Recovery
2 Feedback
from Control Room 6.5e-03 LD 5.6e-02A-8-05.01,
Step 20 -Uncap and throttle
open RCIC-27 condenser
cooling water 1.3e-02 7.3e-0422 starting
YS 6082 drain. Close when steam is present.Recovery
2 Feedback
from Control Room 6.5e-03 LD 5.6e-02A.8-05.01
Steps 17, Throttle
MO-2080 and control as necessary
18,25,26
13e02 1.4e04Recovery
1 Feedback
from I&C Level Monitoring
5.0e-02 MD 1.9e-01Recovery
2 Feedback
from Control Room 6.5e-03 LD 5.6e-02A.8-05-01,
Step 2, At D31, Access Control -SET UP for Monitoring
RX Vessel 1.3e-02 7.3e-04at D31 level by opening circuits
and kick out to Part BRecovery
2 Feedback
from Control Room 6.5e-03 LD 5.6e-02A.8-05-01,
Step 2, At D100, 1st Floor EFT -SET UP for Monitoring
RX Vessel level 1.3e-02 7.3e-04At EFT by opening circuits
and kick out to Part BRecovery
2 Feedback
from Control Room 6.5e-03 LD 5.6e-02Part B, Steps 29 & SET UP for Monitoring
RX Vessel level by selecting
level30 -MCR instrument
and attaching
Fluke 707 monitoring
device -7.2e-02 1.1e-02Control RoomRecovery
2 Feedback
from Control Room 6.5e-03 MD 1.5e-01Part B, Steps 29 & SET UP for Monitoring
RX Vessel level by selecting
level30 -CSR Instrument
and attaching
Fluke 707 monitoring
device -Cable 7.2e-02 4.0e-03Spreading
Room__Recovery
2 Feedback
from Control Room 6.5e-03 LD 5.6e-02Part B, Steps 29 & SET UP for Monitoring
RX Vessel level by selecting
level 7.2e-02 4.0e-0330 -EFT instrument
and attaching
Fluke 707 monitoring
device -EFTRecovery
2 Feedback
from Control Room 6.5e-03 LD 5.6e-02Part B, Steps 29 & SET UP for Monitoring
RX Vessel level by selecting
level31 -RxB Instrument
and attaching
Fluke 707 monitoring
device -7.2e-02 4.0e-03Reactor BuildingRecovery
2 Feedback
from Control Room 6.5e-03 LD 5.6e-02Part B, Step 32 MONITOR OF RX VESSEL WITH FLUKE 707 (Conducted
1.3e-02 7.3e-04separately
by I&C)Recovery
2 Feedback
from Control Room 6.5e-03 LD 5.6e-02Part B, Step 32c Interpret
Fluke monitor readings
using density compensation
tables In B.1.1 operations
manual, section 6 (posted In Control 7.2e-02 7.0e-03I Room)Recovery
I Feedback
from I&C Level Monitoring
5.0e-02 LD 9.8e-02Revision
2 Page A-17Revision
2Page A-17
1SML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSI SMLI 6012.000-1
Appendix
A -HRA CALCULATOR
REPORTSCritical
StA.8-05.05
A.8-05.01,
ep No. Recovery
Step No. .ý.Action.
HEP (Crit) HEP (Rec) Dep. Cond. HEP sTotapfor
(Rec) : *stepMaintain
CST level and verify valve status in the steam chase 2.8e-02 1.6e-03Recovery
2 Feedback
from Control Room 6.5e-03 LD 5.6e-02Step 9 Remove the pin securing
the slip link to the governor
lever toprevent interference
from the hydraulic
governor
(See 5.7e-02 5.7e-02Attachment
1)Total Unrecovered:.
5.2e-01 Total Recovered:
9.2e-02Revision
2 Page A-18Revision
2Page A-1 8
ISML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSA.2. HPV_SBO_FLOOD,
Fail to operate the HPV using N2 bottles to providecontainment
heat removal during SBO/Flood
Basic Event SummaryPlant DataFile
...File;Size.
File Datei ."Re&cordDate
Monticello
Ext 901120 06/28/13
06/28/13Flooding
SDPHRA June2013.HRAJohn Spaargaren
& PierreMacheret,
Hughes Associates
Table 46: HPVSBOFLOOD
SUMMARY... .._*__"___._."_
__.___ '._____HEP
Sumrnhiaty
3.le-02 2.3e-01With Recovery
6.1e-04 1.3e-02 1.3e-02 5Initial Cue:Drywell pressure
above 2 psigCue Comments:
The cue for action is that the TSC has recommended
venting the DW by using the Hard Pipe Vent usingprocedure
A.8-05.08,
Manually
Open Containment
Vent Lines.Initial procedure
entered on high drywell pressure
is C.5-1200.
The DW/Torus
Pressure
leg directsoperators
to C.5-3505.
For the limiting
PRA case, it is assumed that normal and alternate
andpower via Y-80 is not available
and operators
must therefore
use A.8-05.08
to install pre-staged
nitrogenbottles directly
to the inboard and outboard
HPV isolation
valves to open them.Due to the SBO, it is assumed that there will be multiple
impacts to indications,
so the degree of clarityhas been set at "Poor".Degree of Clarity of Cues & Indications:
PoorProcedures:
Cognitive:
C.5-1200
(PRIMARY
CONTAINMENT
CONTROL flowchart
(Monticello))
Revision:
16Execution:
A.8-05.08
(Manually
Open Containment
Vent Lines) Revision:
1Other: A.6 (ACTS OF NATURE (Monticello))
Revision:
43Other: C.5-3505-A
0 Revision:
10Cognitive
Procedure:
Step: DW/TORUS
PRESSURERevision
2 Page A-19Revision
2Page A-1 9
1SML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSInstruction:
BEFORE DW pressure
reaches Fig. D, DW Pressure
Limit (56 psig) vent to stay below Fig. D,DW Pressure
Limit per C.5-3505Procedure
and Training
Notes:Three JPM trials were performed
emulating
the specific
external
flooding
conditions
of this scenario
on 18June 2013. Observations
were factored
into this analysis.
Training:
Classroom,
Frequency:
0.5 per yearSimulator,
Frequency:
0.5 per yearJPM Procedure:
JPM-A.8-05.08-001
(Manually
Open Containment
Vent Lines) Revision:
0Identification
and Definition:
This HFE is for the external
flooding
model for venting prior to core damage.1. Initial Conditions:
SBO due to external
flooding.
2. Initiating
Events: External
flooding
causes station blackout.
3. Accident
sequence
(preceding
functional
failures
and successes):
No containment
venting or heat removalNeed to vent to maintain
containment
integrity
prior to ultimate
containment
pressure
for RCIC injection
4. Preceding
operator
error or success in sequence:
None.5. Operator
action success criterion:
Align pre-staged
alternate
bottles directly
to AO-4539 andAO-4540 (located
on the torus catwalk)
to open the hard pipe vent.6: Consequence
of failure:
Failure to vent containment
leads to containment
failure.
Any subsequent
release will likely be through an unscrubbed
and unfiltered
release path.Key Assumptions:
JPM A.8-05.08-001,
Rev. 0, Manually
Open Containment
Vent LinesINITIAL CONDITIONS:
o Extreme flooding
has led to a Station Blackout
that has. existed at Monticello
for the last 10hours.o Div. 1 and Div 2 250 VDC battery systems have been depleted
and are not available.
o The plant was in Shutdown
Cooling until the station blackout
and has since been slowlyrepressurizing
due to heating up.o Current RPV pressure
is 75 psig-and
slowly rising.o H SRV has failed to reseat and indication
of the tailpipe
vacuum breaker sticking
open have led toa Drywell pressure
of 45 psig and rising about 1 psig every 30 minutes.o Efforts to align the diesel fire pump to DW sprays have been unsuccessful
due to the flooding.
o The TSC has recommended
venting the DW by using the Hard Pipe Vent using procedure
A.8-05.08, Manually
Open Containment
Vent LinesINITIATING
CUES (IF APPLICABLE):
o The CRS directs operator
to initiate
DW venting through the Hard Pipe Vent lAW procedure
A.8-05.08, Manually
Open Containment
Vent Lines, Parts A and B.Revision
2Page A-20
1SML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSHard Pipe Vent local manual operation
Job Performance
Measure entry condition
assumptions,
Information
excerpted
from Hughes Associates
Record of Correspondence,
Hard Pipe Vent ManualOperation
e-mails with Xcel Energy during June 2013, Hughes Associates,
Baltimore,
MD, 7 July 2013:Conditions
anticipated
following
a SBO resulting
from an external
flooding
event:o ERO has been manned for the past several days, with these procedures
predicted
and plannedto be implemented
ahead of timeo Plant is in cold shutdown
condition
(mode 4)o Operations
staffing
to perform the procedures
would be optimal (several
operators
assigned
asdesired to each procedure)
o Environment
would be consistent
with SBO (hot, dark, damp)o There would be more than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> to perform the procedures,
allowing
several opportunities
totroubleshoot
and/or re-perform
steps if necessary
o The ERO would place maximum priority
on maximizing
chances of successful
performance
ofthese procedures
Operator
Interview
Insights:
The JPM that was completed
by Xcel with 2 ROs and 2 NLOs was JPM A.8-05.08-001,
Rev. 0, ManuallyOpen Containment
Vent Lines. The average time to complete
the JPM was 30 minutes given theinformation
that the N2 bottles were staged on the CRD catwalk.
There were no problems
or issues thatrequired
any of the operators
to stop and get clarifying
information,
it was identified
that removing
fittingswas not the best idea it would be better if the lines had tee's installed
where the caps could be removedand the appropriate
lines connected.
This way the capped connection
could be labeled to furtherminimize
connecting
to the wrong fitting.
The operators
stated that strips of non-skid
should be placed onthe areas around the site for safety reasons.
They also mentioned
using the LED headlights
versusflashlights
to allow both hands to be free.Manpower
Requirements:
..._....._.____"_
Ci~Wei~ier
hclu~de~d::
TotaAIIVailale
4KRqiiiredfr
'Noe____________
Ex'c~itip'"in
_ _ _ __ _Reactor operators
Yes 2 1Plant operators
Yes 2 0Mechanics
Yes 2 0Electricians
Yes 2 0I&C Technicians
Yes 2 0Health Physics Technicians
Yes 2 0Chemistry
Technicians
Yes 1 0Execution
Performance
Shapina Factors:Environment:
Lighting
PortableHeat/Humidity
Hot / HumidRadiation
Background
Atmosphere
Steam (although
steam will notbe present,
this PSF was usedto indicate
an off-normal
condition,
such as would bepresent for flood and SBO)Special Requirements:
Tools RequiredAdequateAvailable
Parts RequiredI I_ AdequateRevision
2Page A-21
1SML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSClothing
RequiredAdequateComplexity
of Response:
Cognitive
ComplexExecution
ComplexEquipment
Accessibility
Main Control Room Accessible
(Cognitive):
Equipment
Accessibility
Reactor Building
With Difficulty
(Execution):
Stress: HighPlant Response
As Expected:
YesWorkload:
HighI Performance
Shaping Factors:
NegativePerformance
Shaping Factor Notes:The response
is considered
to be Complex due to the flooding
and SBO impacts to lighting
andaccessibility.
Flashlights,
headlamps
and boots were considered
necessary
by Training
when the JPMswere performed
for these tasks.The Equipment
Accessibility
is evaluated
as With Difficulty
due to Rx building
lighting
and flooding
issues.Key Assumptions
(see that section)
regarding
the conditions
provided
to Training
for performing
the JPMfor this task said that the "Environment
would be consistent
with SBO (hot, dark, damp)". The Traininginsights
from the JPM performance
stated that the operators
recommended
the use of "LED headlights
versus flashlights",
so it is clear that portable
lighting
is used.Despite preparations
and training,
the flooding
scenario
is considered
to be a high stress situation.
The steps identified
as Critical
in JPM-A.8-05.08-001
were used for the Execution
quantification.
Timing:T SW15.00 HoursT 5.50 HoursdelayT1/2 10.00 MinutesTM 45.00 MinutesM ~ I1CueIIrreversible
DamageState
I-I.t=0Timing Analysis:
TO = Station Blackout.
Tsw = Per MAAP run Rcic-dgl
3-cts-ABS
performed
in support of an external
flooding
SDP, containment
pressure
reaches 56 psig at 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> following
a SBO (flooding
>930'). Core temperature
reaches 1800degrees F at 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> due to CST depletion
and no transfer
of RCIC to the torus. This is conservative
timing as refilling
of the CST is very likely.Td = 5.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> -Based on an interview
conducted
in a prior analysis
with a senior Shift Manager,
theorder to begin the procedure
to manually
operate the hard pipe vent would be given at approximately
27psig containment
pressure.
This is due to the step in C.5-1200
(DW/Torus
Pressure
leg) that says if youcannot restore and maintain
drywell pressure
within Figure 0 (27psig for 0 ft torus level), then maintaindrywell pressure
less than Figure D (56 psig).The 5.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> is based on MAAP run Rcic-dg13-cts-ABS
as the time when drywell pressure
reaches 42psia (27 psig) [Worksheet
d43-1, column AC Drywell Pressure]
T1/2 = According
to the initial conditions
assumed by Training
for the Job Performance
Measureperformed
for this task, the ERO will have been manned for the past several days, with these procedures
Revision
2Page A-22
1 SML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSpredicted
and planned to be implemented
ahead of time. Daily planning
meetings
will have been held todiscuss actions to be taken, so the 10 minutes is simply an estimate
of the meeting time between TSCand ERF personnel
to make the actual decision
to vent the DW by using the Hard Pipe Vent. The controlroom supervisor
(CRS) will then direct operators
to initiate
the process.Tm = Results of HPV local manual operation
Job Performance
Measure A.8-05.08-001
performed
18June 2013. The procedure
was performed
four times, taking an average of 30 minutes.
Additional
15minutes for C.5-3505-A
steps 3 and 4.Time available
for cognition
and recovery:
525.00 MinutesTime available
for recovery:
515.00 MinutesSPAR-H Available
time (cognitive):
525.00 MinutesSPAR-H Available
time (execution)
ratio: 12.44Minimum level of dependence
for recovery:
ZDRevision
2Page A-23
1SMLII16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSCognitive
Unrecovered
HPVSBOFLOOD
Table 47: HPVSBOFLOOD
COGNITIVE
UNRECOVERED
- Pc Failure .Mecdhanism
... -". 1 .1 ." 1 1 .Branch : .HEP.::..Pca: Availability
of Information
d 1.5e-03PCb: Failure of Attention
m 1.5e-02Pcc: Misread/miscommunicate
data e 3.0e-03Pcd: Information
misleading
b 3.0e-03Pce: Skip a step in procedure
e 2.0e-03Pcf: Misinterpret
instruction
a neg.Pcg: Misinterpret
decision
logic c 6.0e-03PCh: Deliberate
violation
a neg.Sum of Pca through PCh = Initial Pc = 3.1e-02Notes:Presumed
that SBO causes issues with normal alarms and indications
so pc-a through -d were adjustedconsistent
with insights
from EPRI 1025294,
A Preliminary
Approach
to Human Reliability
Analysis
forExtemal Events with a Focus on Seismic,
October 2012.Revision
2 Page A-24Revision
2Page A-24
1SML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSpca: Avlabhty
of infonnation
Indiation
ail in CR Indication
bminglAlftmate
Training
onCR Accurate
in Procedure
Indcators
I.0e-01 (a) neg..Oe.00 1.0e+00 (b) neg.O.0e4.00
I .oe-o (c) neg-7- e0(d) 1-pe-03Yes 5.0e-0 (e) 5.0e-02No1.e+00
f) 5.oe-o01.0e+001.0e-+O (g) .0" WOMCR indications
may not be accurate
due to the Station Blackout,
however,
either procedural
or informalcrew information
on alternate
indications
and training
should provide operator
input to decision-making.
pcrb: Failure of attention
Low vs. Hi Check vs. Monitor Front vs. Back Aarmed vs.NotWokdload
Panel AlarmedEvout(a)
neg-O.Oe0 Back .0(b) 1.5e-4LOW 3.0e-03 (c) 3.0e-031.0e+001.0e+00 Front 5e-2(d) 1.-%-045.0e-02OMonitor I0-0e+00
l(e) 3.0e-033.0e-03 Back 5.0e-02 (f) 3.0e-041. Nice 3.0e-03 1(g) 6.0e-032. ic Fro,,t 15.,10 (h eg-5(b0n-02Check O.Oe+0 18 0(i) neg.0.0e*WBack
(.0e.so5.0e-02e-04
WIgh 3.0e-03 1Ae(k) 1.e-02Front ()7.5e-04
Monitor --- Oe --0- (m) I.5e-023 -Back 50e-02 (n) 1.5e-033.Oe-03 I1.0e0 (o) 3.0e-02Revision
2 Page A-25Revision
2Page A-25
I SM L16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSISM LI 6012.000-1
Appendix
A -HRA CALCULATOR
REPORTSpcc: Misreadftniscmmnnicate
dataInhicators
Easy to Good--ad
Indicator
Fom- --Locate cminunicafions
I O.Oe.H) (a) neg.O.Oe.)O 3i 3 (b) 3.0e-03, O-Oe+0 (c) 1.0e-030(g) 4.0e-031.0e-03 (h) 4.0e-033.0e-03o.oe-4oo
(g) 3.Oe-0313.0e-033.oe-o3 (h) 7.Oe-O3pcd: Infonmtion
fidNilngM Cuesas Stated Warnng SpecoTc Tbn,,ig e TiningDire IIo.oe+0o (a) meg.No--------------------
(b) 3Je-03.0-L-02 (c) 1.0e-021..eOe0 1..od-o (d) 1.Oe-O11.Oe+OO (e) 1.0e" 0MCR indications
may not be accurate
due to the Station Blackout
so cues may not be as stated inprocedures.
pce: Sli a step in procedure
Obvious Ms Eing s Mlle V& MUPleawaf
cekeqing
A&d13.Oe-O3(a)
1 .0e-033.3e-01 (b) 3.Oe-031.0e.-02O.e.O0 3(c) 3.0e-03.Oe.001e-0
(d) 1.8e-02-(e) 4-e-033.3e-o------.----
Yes3.0e-03
13.e-3 (g) 6.0e-031.Oe4-OI
(h) I.3e-021..0e-021.0e-01 (i) t.0e -0tRevision
2 Page A-26Revision
2Page A-26
1SML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSI SMLI 6012.000-1
Appendix
A -HRA CALCULATOR
REPORTSpf: Misinterpret
instruction
Standard
or AM Required
7haning on StepAmbiguous
wonling Information
--- ------- ------- ---------
--- (a) neg.(b) 3.oe-033.0e-02 (c) 3.0e-02NO .0e4H (d) 3.0e-03o.e-,.o I(e) 3.0e-023.0e-02 1.0e-01 (f) 6.Oe-033.0e..02
I 0 (g) 6.0e-02pcg: Mi§sinrmpt
decision
ogicNMor statemmut
-ir*N or -ow- Both AND' & IPracticed
ScenailStatement
"OFr3.3e41 (a) 1.Ge-023.0e-02 (b) 4.9--021.2-02 -3(c) 6.0e-0333.ie-Ol-
.Oe. (d) .9e-026.0e-03 (1.0e.9.42
3.3e-1 (e) 2.0e-03O.Oe-Oe-0
Yes OO + 1.00,6 0O (f) 6.0e-03(g) t.Oe-02No 3.0e-02 --(h) 3.1e-021.0e30.-0
I.0e-03 30"1 3.0e-0M13.3e-01
(k) neg.O.OedO l- (1) neg.pch: Deliberate
violation
Belef in Adequacy
Adverse Reasonable
Poky ofof Instructon
Consequence
if Alternatis
"'Verbatic"
oew-------
--- ------- ------- ---------
------ (a) neg.Yes 5.0eM (b) 5.0"-01oI. (c) 1.0e4WI.Oe4O110e00
O.Oe,.O0
(d) neg.Io.oe.,o
(e) neg.Revision
2 Page A-27Revision
2Page A-27
1SML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSI SMLI 6012.000-1
Appendix
A -HRA CALCULATOR
REPORTSCognitive
RecoveryHPVSBOFLOOD
Table 48: HPVSBOFLOOD
COGNITIVE
RECOVERY< a) (" I- LL '.D FinalInitiaIIl.
HE > Z 1 -'5: -r-.O Value0CO W nOa C -O) Lu ValuePc. 1.5e-03 X X -2.5e-01 3.8e-04Pcb: 1.5e-02 X X X MD 3.8e-03 5.7e-05Pc': 3.0e-03 X X MD 2.1e-02 6.3e-05PCd: 3.0e-03 X X X MD 7.3e-03 2.2e-05<PCe: 2.0e-03 X X X MD 1.0e-02 2.0e-05, :; neg. -1.0e+00P. 6.e-03 X X X MD 1.1 e-02 6.6e-05-I--neg. 1.0e+00P 6 SuoP dt 6.1e-04Notes:Due to long timeframe
and severity
of scenario,
STA and Emergency
Response
Facility
will be available.
Operations
staffing
to perform the procedures
was assessed
by Xcel as optimal (several
operators
assigned
as desired to each procedure)
so Extra Crew was credited.
Used Moderate
Dependency
due to high stress.Revision
2 Page A-28Revision
2Page A-28
1SML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSISM LI 6012.000-1
Appendix
A -HRA CALCULATOR
REPORTSExecution
Unrecovered
HPVSBOFLOOD
Table 49: HPVSBOFLOOD
EXECUTION
UNRECOVERED
ProcedurYe
C:A8-5.08,eManuallyOpen
Containm
ent CvehtLines
., omment Stress Over RideI IStep.No.*
jnstructionlComnent,-,
Error' -,. HTHERP HEP Factor.,Type' Table Item -..___- _Connect and apply pressure
from AH-1 cylinder
to rupture Rupture DiskPSD-4543A.8-05.08,
Step 4 Location:
Reactor Building
EOM 20-7b 2 1.3e-03EOC 20-12 5 1.3E-3Total Step HEP 1.3e-02Connect and adjust AH-1 regulator
to less than 100 psig and slowly openAH-1 discharge
valve to open valve AO-4539 5A.8-05.08,
Step 5 Location:
Reactor Building
EOM 20-7b 4 4.3e-03EOC 20-13 5 1.3E-2Total Step HEP 8.7e-02Connect and adjust AH-2 regulator
to less than 100 psig and slowly openAH-2 discharge
valve to fully open valve AO-4540 5A.8-05.08,
Step 6 Location:
Reactor Building
EOM 20-7b 4 4.3e-03EOC 20-13 5 1.3E-2 ITotal Step HEP 8.7e-02Open and Close the HPV isolation
valves as directed
by shift supervisor
C.5-3505
Part A, Location:
Reactor Building
EOM 20-7b 1 4.3e-04 5Step 3 1 EOC 20-13 2 3.8E-3 ITotal Step HEP 2.1e-02Monitor Containment
Pressure
and Radiation
Levels in the Hard PipeC.5-3505
Part A Vent. 5Step 4 Location:
Reactor Building
EOM 20-7b 1 4.3e-04Step 4 EOC 20-10 1 3.8E-3Total Step HEP 2.1e-02Feedback
from Control Room 5Recovery
Location:
Main Control Room EOM 20-7b 3 1.3e-03 ITotal Step HEP 6.5e-03Revision
2 Page A-29Revision
2Page A-29
1SML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSExecution
RecoveryHPV_SBOFLOOD
Table 4-10: HPVSBOFLOOD
EXECUTION
RECOVERYc it.Recovery
Step No.. -i HEP (crit)i HEP'Rec .Dep. P"Cond. :.Totalffor.
~Criticalý
'te k o .__________
_______________________________________________________
....___.... ..._(Rec) StepA.8-05.08,
Step 4 Connect and apply pressure
from AH-1 cylinder
to rupture 1.3e-02 7.3e-04Rupture Disk PSD-4543Recovery
Feedback
from Control Room 6.5e-03 LD 5.6e-02A.8-05.08,
Step 5 Connect and adjust AH-1 regulator
to less than 100 psig andslowly open AH-1 discharge
valve to open valve AO-4539 8.7e-02 4.9e-03Recovery
Feedback
from Control Room 6.5e-03 LD 5.6e-02A.8-05.08,
Step 6 Connect and adjust AH-2 regulator
to less than 100 pslg and 8.7e-02 4.9e-03slowly open AH-2 discharge
valve to fully open valve AO-4540Recovery
Feedback
from Control Room 6.5e-03 LD 5.6e-02C.5-3505
Part A, Open and Close the HPV isolation
valves as directed
by shift 2.1 e-02 1.2e-03Step 3 supervisor
Recovery
Feedback
from Control Room 6.5e-03 LD 5.6e-02C.5-3505
Part A, Monitor Containment
Pressure
and Radiation
Levels in the 2.1 e-02 1.2e-03Step 4 1 Hard Pipe Vent.I Recovery
Feedback
from Control Room 6.5e-03 LD 5.6e-02-* .: .Total ....I.- Unrecoered:-
2.3e1- .Total R 2ovIered:
1.3e2Revision
2 Page A-30Revision
2Page A-30
ISML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSA.3. RCICSBOFLOOD,
Fail to manually
operate RCIC during SBO and extremeflooding
conditions
(SPAR-H)Basic Event Summary'Planlt;:".. i. Data :File Dati e
- Rebo d
- :".Monticello
Ext 909312 07/02/13
07/02/13Flooding
SDPHRAJune2013_SPAR
Hquant forsensitivity.HRA
Table 11: RCIC_SBOFLOOD
SUMMARY[Ana l, i Resu!ts:.-I4
Cognitive
Execution
[Failor
3.2e.. 9.1 e-021 .4e-01Plant:Monticello
Initiating
Event:External
Flood + SBOBasic Event Context:The flooding
engineer
provides
daily updates to the station on high river water levels including
potentials
to rise above any A.6 trigger points. At this point, heightened
awareness
of the potential
for flooding
isimplemented.
When river level exceeds 921 feet an evaluation
of EALs would be performed.
If visible damage hasoccurred
due to flood water rising greater than 921 feet, then an Alert per EAL HA1.6 would be declared.
Prior to river levels reaching
these levels, operators
would be walking down the A.8 procedures
foralternate
methods to vent primary containment
and operate RCIC remotely.
This would involve staging ofequipment
in the torus area to open the Hard Pipe Vent and verification
that equipment
is properly
stagedto operate RCIC remotely.
EDGs and batteries
are not available.
Shutdown
cooling,
HPCI, and RCIC are not available
from normalelectrical
means. RCIC is available
for manual operation.
Operators
have temporary
level indication
setup in the reactor building.
Pressure
indication
is available
inthe direct area of the level transmitters.
The building
is dark and most likely water in the basement
of thereactor building.
Additional
portable
lights are available
to assist with lighting
and boots staged for higherwater. The operators
would utilize A.8-05.01
to un-latch
the governor
from the remote servo linkage andthrottle
steam flow to RCIC to start the turbine rolling while coordinating
with operators
monitoring
waterlevel and reactor pressure.
Upon reaching
the high end of the level band the operators
would throttleclosed the steam admission
valve and await direction
to re-start
RCIC. Local operation
of RCIC isdemonstrated
each refueling
outage during the over speed test. Operation
of a coupled turbine run isless complex because the turbine is easier to control with a load.Revision
2Page A-31
ISML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSTiming:T 7.97 HoursT delay 5.75 Hours i T1/2 10.00 Minutes TM 80.00 Minutes1Irreversible
Cue DamageState
t=oTiming Analysis:
TO = Station BlackoutTsw = Time from Station Blackout
to the time by which RCIC must be restored.
Per Monticello
MAAP Calculations,
case "SBOCase3-RI",
27 June 2013:Time to TAF = 7.17 hrsTime to -149" = 7.2 hrsTime to 1800 F = 7.97 hrsDamage is assumed to occur if the temperature
exceeds 1800 F or 7.97 hrs, so this was used as the timeby which RCIC restoration
is required.
Tdelay = PRA battery calc (PRA-CALC-1
1-002) indicates
that there are 5.75 hrs until RCIC batterydepletion.
Also, the RCIC Water Flow (column BC) of the d41 tabs in the "SBOCase3-RI"
MAAPanalysis
spreadsheet
shows that RCIC injection
stops at approximately
the same time (5.74 hrs), so theMAAP runs agree with the calc. This Tdelay can be considered
somewhat
conservative,
since in reality,
itis likely that an action would be taken before waiting for battery depletion.
T1/2 = The cue for action is that the TSC and the Emergency
Response
Director
have determined
thatRCIC operation
is needed. Daily planning
meetings
will have been held to discuss actions to be taken assoon as the diesels are lost, so the 10 minutes is simply an estimate
of the meeting time between TSCand ERF personnel
to make the actual decision
to manually
operate RCIC. The Control Room Supervisor
(CRS) directs operator
to initiate
RCIC and inject into the RPV using procedure
A.8-05.01,
ManualOperation
of RCIC, Part A, Placing RCIC in Service.Tm = Results of RCIC local manual operation
Job Performance
Measure performed
18 June 2013. Theprocedure
was performed
three times, taking 49 minutes,
37 minutes and 50 minutes to complete
for anaverage time of 45 minutes.
50 minutes was used as the conservative
value for JPM performance.
The JPM did not include the performance
of Part B for installation
and use of the Fluke level monitoring
device; this was estimated
to require 30 minutes,
so the total time for Tm was estimated
as 50 min + 30min = 80 min.Time available
for recovery:
43.20 MinutesSPAR-H Available
time (cognitive):
53.20 MinutesSPAR-H Available
time (execution)
ratio: 1.54Minimum level of dependence
for recovery:
LDRevision
2 Page A-32Revision
2Page A-32
1SML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSISMLI6OI2.000.1
Appendix
A -HRA CALCULATOR
REPORTSPART I. DIAGNOSIS
PSFss PSF ,ve;s9 %fMultlper~or<.
Available
Time Inadequate
Time P(failure)
= 1.0(recommended
choice Barely adequate
time (~ 2/3 x nominal)
10based on timing Nominal time 1information
in bold) Extra time (between
1 and 2 x nominal 0.1and > 30 min)Expansive
time (> 2 x nominal and > 30 X 0.01min)Insufficient
Information
IStress Extreme 5High X 2Nominal 1Insufficient
Information
IComplexity
Highly complex 5Moderately
complex X 2Nominal 1Obvious diagnosis
0.1Insufficient
Information
1Experience/Training
Low 10Nominal X 1High 0.5Insufficient
Information
1Procedures
Not available
50Incomplete
20Available,
but poor 5Nominal X 1Diagnostic/symptom
oriented
0.5Insufficient
Information
1ErgonomicslHMI
Missing/MisleadingJ
50Poor 10Nominal X IGood 0.5Insufficient
Information
1Fitness for Duty Unfit P(failure)
= 1.0Degraded
Fitness 5Nominal X 1Insufficient
Information
1Work Processes
Poor 2Nominal 1Good X 0.8Insufficient
Information
1Revision
2 Page A-33Revision
2Page A-33
ISM LI6012.000-1ApndxA-HACLUTORERS
Appendix
A -HRA CALCULATOR
REPORTSDiagnosis
HEP:3.2e-04PART I1. ACTIONPSFs PSF IUVeis. ~ Multi 11ýr for.__________________
griagn sisAvailable
Time Inadequate
Time P(failure)
= 1.0(recommended
choice Time available
is -the time required
10based on timing Nominal time X 1information
in bold) Time available
>= 5x the time required
0.1Time available
>= 50x the time required
0.01Insufficient
Information
1Stress/Stressors
Extreme 5High X 2Nominal 1Insufficient
Information
1Complexity
Highly complex 5Moderately
complex X 2Nominal 1Insufficient
Information
1Experience/Training
Low 3Nominal X 1High 0.5Insufficient
Information
1Procedures
Not available
50Incomplete
20Available,
but poor X 5Nominal 1Insufficient
Information
1Ergonomics/HMI
Missing/Misleading
50Poor X 10Nominal 1Good 0.5Insufficient
Information
1Fitness for Duty Unfit P(failure)
= 1.0Degraded
Fitness 5Nominal X 1Insufficient
Information
1Work Processes
Poor 5Nominal 1Good X 0.5Insufficient
Information
0.5Revision
2 Page A-34Revision
2Page A-34
ISML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSAction Probability:
9.1e-02 [Adjustment
applied:
1.0e-3 * 1.0e+02 / (1.0e-3 * (1.0e+02
-1) + 1)]PART Ill. DEPENDENCY
caeI Im In~ mC..-mhwamccwiTask Failure WITHOUT Formal Dependence:
9.1le-02Task Failure WITH Formal Dependence:
1 .4e-01Revision
2 Page A-35Revision
2Page A-35
ISML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSA.4. HPVSBOFLOOD,
Fail to operate the HPV using N2 bottles to providecontainment
heat removal during SBO/Flood
(SPAR-H)Basic Event Summary.:Plant , :Datale FileSize"..
- FileDate
- Rerd DateMonticello
Ext 901120 06/28/13
06/28/13Flooding
SDPHRAJune2013-SPAR
Hquant for1 sensitivity.HRA
John Spaargaren
& PierreMacheret,
Hughes Associates
Table 412: HPVSBOFLOOD
SUMMARYAnalyssResults-,*
Cognitive
Execution
Fe ! rN r 1b6 1i.ii 3.2e-04 5.0e-03Total :HEP. I 5.5e-02Plant:Monticello
Initiating
Event:External
Flood + SBOBasic Event Context:The flooding
engineer
provides
daily updates to the station on high river water levels including
potentials
to rise above any A.6 trigger points. At this point, heightened
awareness
of the potential
for flooding
isimplemented.
When river level exceeds 921 feet an evaluation
of EALs would be performed.
If visible damage hasoccurred
due to flood water rising greater than 921 feet, then an Alert per EAL HA1.6 would be declared.
Prior to river levels reaching
these levels, operators
would be walking down the A.8 procedures
foralternate
methods to vent primary containment
and operate RCIC remotely.
This would involve staging ofequipment
in the torus area to open the Hard Pipe Vent and verification
that equipment
is properly
stagedto operate RCIC remotely.
EDGs and batteries
are not available.
Shutdown
cooling,
HPCI, and RCIC are not available
from normalelectrical
means. RCIC is available
for manual operation.
Revision
2 Page A-36Revision
2Page A-36
1SML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSTimina:T S 15.00 HoursTdelay 5.50 Hours T1/2 10.00 Minutes TM 45.00 MinutesIreversible
Cue DamageState
t=oAnalysis:
TO = Station Blackout.
Tsw = Per MAAP run Rcic-dg13-cts-ABS
performed
in support of an external
flooding
SDP, containment
pressure
reaches 56 psig at 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> following
a SBO (flooding
>930'). Core temperature
reaches 1800degrees F at 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> due to CST depletion
and no transfer
of RCIC to the torus. This is conservative
timing as refilling
of the CST is very likely.Td = 5.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> -Based on an interview
conducted
in a prior analysis
with a senior Shift Manager,
theorder to begin the procedure
to manually
operate the hard pipe vent would be given at approximately
27psig containment
pressure.
This is due to the step in C.5-1200
(DW/Torus
Pressure
leg) that says if youcannot restore and maintain
drywell pressure
within Figure 0 (27psig for 0 ft torus level), then maintaindrywell pressure
less than Figure D (56 psig).The 5.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> is based on MAAP run Rcic-dg13-cts-ABS
as the time when drywell pressure
reaches 42psia (27 psig) [Worksheet
d43-1, column AC Drywell Pressure]
T1/2 = According
to the initial conditions
assumed by Training
for the Job Performance
Measureperformed
for this task, the ERO will have been manned for the past several days, with these procedures
predicted
and planned to be implemented
ahead of time. Daily planning
meetings
will have been held todiscuss actions to be taken, so the 10 minutes is simply an estimate
of the meeting time between TSCand ERF personnel
to make the actual decision
to vent the DW by using the Hard Pipe Vent. The controlroom supervisor
(CRS) will then direct operators
to initiate
the process.Tm = Results of HPV local manual operation
Job Performance
Measure A.8-05.08-001
performed
18June 2013. The procedure
was performed
four times, taking an average of 30 minutes.
Additional
15minutes for C.5-3505-A
steps 3 and 4.Time available
for recovery:
515.00 MinutesSPAR-H Available
time (cognitive):
525.00 MinutesSPAR-H Available
time (execution)
ratio: 12.44Minimum level of dependence
for recovery:
ZDRevision
2 Page A-37Revision
2Page A-37
1SML16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSPART I. DIAGNOSIS
P PSFs,6V , AfPSF vels u-ti'for-Dagposis,
Available
Time Inadequate
Time P(failure)
= 1.0(recommended
choice Barely adequate
time (~ 2/3 x nominal)
10based on timing Nominal time 1information
in bold) Extra time (between
1 and 2 x nominal 0.1and > 30 min)Expansive
time (> 2 x nominal and > 30 X 0.01min)Insufficient
Information
Stress Extreme 5High X 2Nominal 1Insufficient
Information
1Complexity
Highly complex 5Moderately
complex X 2Nominal 1Obvious diagnosis
0.1Insufficient
Information
1Experience/Training
Low 10Nominal X 1High 0.5Insufficient
Information
1Procedures
Not available
50Incomplete
20Available,
but poor 5Nominal X 1Diagnostic/symptom
oriented
0.5Insufficient
Information
1Ergonomics/HMI
Missing/Misleading
50Poor 10Nominal X 1Good 0.5Insufficient
Information
1Fitness for Duty Unfit P(failure)
= 1.0Degraded
Fitness 5Nominal X 1Insufficient
Information
1Work Processes
Poor 2Nominal 1Good X 0.8Insufficient
Information
1Revision
2 Page A-38Revision
2Page A-38
1 SML-16012.000-I
Appendix
A -HRA CALCULATOR
REPORTSI SMLI 6012.000-1
Appendix
A -HRA CALCULATOR
REPORTSDiagnosis
HEP:3.2e-04PART II. ACTION.PSFs,, PSFLevels'
s Multiplier
forS~ Diagflosis
Available
Time Inadequate
Time P(failure)
= 1.0(recommended
choice Time available
is -the time required
10based on timing Nominal time X 1information
in bold) Time available
>= 5x the time required
0.1Time available
>= 50x the time required
0.01Insufficient
Information
1Stress/Stressors
Extreme 5High X 2Nominal 1Insufficient
Information
1Complexity
Highly complex 5Moderately
complex 2Nominal X IInsufficient
Information
1Experience/Training
Low 3Nominal 1High X 0.5Insufficient
Information
1Procedures
Not available
50Incomplete
20Available,
but poor 5Nominal X 1Insufficient
Information
1Ergonomics/HMI
Missing/Misleading
50Poor X 10Nominal 1Good 0.5Insufficient
Information
IFitness for Duty Unfit P =failure)
1.0Degraded
Fitness 5Nominal X 1Insufficient
Information
1Work Processes
Poor 5Nominal 1Good X 0.5Insufficient
Information
0.5Action Probability:
5.0e-03Revision
2 Page A-39Revision
2Page A-39
ISMLI16012.000-1
Appendix
A -HRA CALCULATOR
REPORTSPART II1. DEPENDENCY
C,=, TD I E I I C ,F.-- -Cb ntin i...,=, ,w M&IMAB ~ F, ibTask. Failre WTHOUForal
D endncesocb addiiorW
khedlafr-I.-ks.
&k*T Faaulia u HD5emTask Failure WITHOUT Formal Dependence:
5.3e-03Task Failure WITH Formal Dependence:
5.5e-02Revision
2 Page A-40Revision
2Page A-40'
ISML16012.000-1
B. APPENDIX
B -EVENT TREESAppendix
B -EVENT TREESRevision
2 Page B-IRevision
2Page B-1
EXTERNAL
FLOOD >930' < 935' EARLY WARNING REACTOR BUILDING
PROTECTED
RCIC/RPV
& HARD PIPE VENT Prob NameSUCCESSFUL
EARLY WARNINGO.OOE+00FLOOD <935'0.891RCIC SUCCESS0.894EXTERNAL
FLOOD >930'[8.90E-06]
[1]SUCCESSFUL
EARLY WARNING[0.106]O.00E+007.09E-068.41 E-070.OOE+007.72E-070.15E-081 07F-07DKOK'D Seq 1:)KDK,D Seq 2MD Seq 3O.00E+00FLOOD > 935'[0.109]RCIC SUCCESSREACTOR BLDG PROTECTED
0.8940.89FAILURE TO PROTECT RB[0.106]1lI[0.11]IMonticello,
Flood SDP 930-935.eta
17/3/2013
1 Page 1IMonticello
Flood SDP 930-935.eta
7/3/2013
Page 1
EXTERNAL
FLOOD >930' < 935' EARLY WARNING REACTOR BUILDING
PROTECTED
RCIC/RPV
& HARD PIPE VENT Prob I NameSUCCESSFUL
EARLY WARNINGO.OOE+00FLOOD <935'0.5in flflF4flf
RCIC SUCCESS1
a; mai--fnr,
[1]0.894'I .uhlt--ub
EXTERNAL
FLOOD >930'[2.00E-05]
[0.106]SUCCESSFUL
EARLY WARNING:)K::)K,D Seq 1:)K,D Seq 2'D Seq 3O.00E÷00FLOOD > 935'[0.5]RCIC SUCCESSREACTOR BLDG PROTECTED
0.8940.89FAILURE TO PROTECT RB7.96E-06-9.43E-07
1.10E-06[0.106][1][0.11]Monticello
Flood SDP 930-935 Sens Freq.eta17/3/2013
1 Page 1
EXTERNAL
FLOOD >930' < 935' EARLY WARNING REACTOR BUILDING
PROTECTED
RCIC/RPV
& HARD PIPE VENT Prob NameSUCCESSFUL
EARLY WARNINGIO.OOE+00FLOOD <935'0.891 1RCIC SUCCESS0.805D.O0E+005.38E-061.55E-06EXTERNAL
FLOOD >930'[8.90E-06]
[1]SUCCESSFUL
EARLY WARNING[0.195]ILl=t =IPI Jt I:)K:)K,D Seq 1:)K:)K'D Seq 2'D Seq 30.OOE+00RCIC SUCCESSFLOOD > 935'[0.109]REACTOR BLDG PROTECTED
0.805[1]0.89] FAILURE TO PROTECT RB[0.195]5.95E-071 .68E-071.07E-07[0.11]Monticello
Flood SDP 930-935 Sens SPAR-H.eta
7/3/2013
Page 1
Enclosure
3Monticello
Nuclear Generating
Plant"Monticello
Flood Protection"
11 Pages Follow
Monticello
Flood Protection
1.0 PURPOSEThe purpose of this document
is to evaluate
the flood protection
provided
at Monticello
Nuclear Generating
Plant (MNGP).Nuclear power plants are designed
to meet robust design criteria,
referred
to as GeneralDesign Criteria
(GDC); which are now codified
as part of NRC regulations
in 10 CFRPart 50. The GDC have existed in various forms prior to being codified
in part 50 andplant commitments
to meet the GDC (or pre-existing
requirements)
depend on the ageof the plant.MNGP was designed
before the publishing
of the 70 General Design Criteria
(GDC) forNuclear Power Plant Construction
Permits proposed
by the Atomic Energy Commission
(AEC) for public comment in July 1967, and constructed
prior to the 1971 publication
ofthe 10 CFR 50, Appendix
A, GDC. As such, MNGP was not licensed
to 10 CFR 50Appendix A, GDC. The MNGP USAR, Section 1.2, lists the Principal
Design Criteria(PDC) for the design, construction
and operation
of the plant. MNGP USAR Appendix
Eprovides
a plant comparative
evaluation
to the 70 proposed
AEC design criteria.
It wasconcluded
in the USAR that the plant conforms
to the intent of the GDC. A listing of thePDC and AEC GDC (by number and title) pertaining
to external
flooding
is providedbelow:PDC 1.2.1 .c "General
Criteria"
"The design of those components
which are important
to the safety of the plantincludes
allowances
for the appropriate
environmental
phenomena
at the site.Those components
important
to safety and required
to operate during accidentconditions
are designed
to operate in the post accident
environment."
AEC Criterion
2 -Performance
Standards
(Category
A)"Those systems and components
of reactor facilities
which are essential
toprevention
of accidents
which could affect the public health and safety or tomitigation
to their consequences
shall be designed,
fabricated,
and erected toperformance
standards
that will enable the facility
to withstand,
without loss ofthe capability
to protect the public, the additional
forces that might be imposed bynatural phenomena
such as earthquakes,
tornadoes,
flooding
conditions,
winds,ice, and other local site effects.
The design bases so established
shall reflect:
(a)appropriate
consideration
of the most severe of these natural phenomena
thathave been recorded
for the site and surrounding
area and (b) an appropriate
margin for withstanding
forces greater than those recorded
to reflectuncertainties
about the historical
data and their suitability
as a basis for design."This evaluation
addresses
the following
aspects of flood protection
that are provided
forthe MNGP to meet AEC Criterion
2:* Flood Analyses
-this discussion
describes
the site location,
hydrology
anddetermination
of the maximum predicted
flood water elevations
and timing.Page 1 of 11
- Flood Mitigation
Strategy
-this discussion
describes
the aspects provided
topreclude
the design bases flood from adversely
impacting
the site. Thisprotection
is provided
by structural
design and procedural
actions.* Flood Protection
Implementation
-this discussion
describes
the actions taken atthe site to provide reasonable
assurance
that flood protection
strategy
can beeffectively
implemented
in a design bases flood scenario.
2.0 FLOOD ANALYSISThis section describes
the site location
and hydrology,
and a summary of current designbasis flood elevations.
Information
in this section is based on information
in the MNGPUpdated Safety Analysis
Report (USAR) (Reference
1); specific
sections
are identified
below.2.1 Site Location
and Description
The plant is located within the city limits of Monticello,
on the right (west)bank of the Mississippi
River. The topography
of the MNGP site is characterized
byrelatively
level bluffs which rise sharply above the river. Three distinct
bluffs exist at theplant site at elevations
920, 930, and 940 ft. above msl. The finished
plant grade isapproximately
930 ft. msl. The plant grade surrounding
Class I and Class II structures
housing Class I equipment
varies between 935 ft. msl and 930 ft. msl. The sitedescription
and topography
is described
in detail in the MNGP USAR, Section 2.2.Hydrology
The Mississippi
River is the major hydrologic
feature for the site. The river poses thesignificant
flooding
source for the site. Table 1, below, summarizes
normal and floodedriver flow rates and water elevations.
Table 1Normal and Flooded River Flow Rates and Water Elevations
River Flow Rate (cfs) Water Elevation
Condition
(ft. msl)Normal 4,600 905Maximum Recorded(1965) 51,000 9161000 Year Flood -90,000 (1) 921Probable
Maximum 364,900 939.2Flood 364,900 _ 939.2(1) Estimated
using USAR Appendix
G, Exhibit 8, for a waterelevation
of 921 ft.Normal river level at the MNGP site is about 905 ft. msl at a distance
1.5 milesupstream,
the normal river elevation
is about 910 ft. msl and at an equal distancedownstream,
the river is at 900 ft. msl. The following
flow statistics
are estimated
for theMississippi
River at the MNGP site:Page 2 of 11
Average Flow -4,600 cubic feet per second (cfs)Minimum Flow -240 cfsMaximum Flow -51,000 cfsThe maximum reported
high water level at the MNGP site was about 916 ft. msl whichwas recorded
during the spring flood of 1965 with an estimated
river flow of 51,000 cfs.The results of flood frequency
study for the 1000 year flood estimated
a peak stage of921 ft. msl (USAR Section 2.4)2.2 Design Basis Flood HazardThe following
flood scenarios
are evaluated
as part of the MNGP licensing
basis [USARAppendix
G]:* Flooding
in Streams and Rivers* Flooding
due to Downstream
Ice Dam Build-UpA summary of the results as described
in Reference
2 for each of these floodingscenarios
is provided
below; specific
sections
from Reference
2 are identified
with theassociated
discussion.
2.2.1 Flooding
in Streams and RiversThe probable
maximum discharge
was determined
to be 364,900 cfs and acorresponding
peak stage of elevation
939.2 ft. msl. The flood would result frommeteorological
conditions
which could occur in the spring and would reach maximumriver level in about 12 days. It was estimated
the flood stage would remain aboveelevation
930.0 ft. msl for approximately
11 days.The most critical
sequence
of events leading to a major flood would be to have anunusually
heavy spring snowfall
and low temperatures
after a period of intermittent
warmspells and sub-freezing
temperatures
has formed an impervious
ground surface andthen a period of extremely
high temperatures
followed
by a major storm. The snowmeltand rainfall
excesses
were then routed to the plant site by computer
modeling.
A stagedischarge
rating curve was then constructed.
The probable
maximum discharge
wasdetermined
to be 364,900 cfs with a corresponding
peak stage elevation
of 939.2 ft. mslfrom the discharge
rating curve.A probable
maximum summer storm over the project area was also studied in detail andthe resulting
flood at the project site determined.
Although
the summer storm was muchlarger than the spring storm, the initial retention
rate of zero for spring conditions,
andthe snowmelt
contribution
to runoff, resulted
in the spring storm producing
the morecritical
flood.Key Assumptions
Used to Determine
Design Basis Flood HazardThe PMF evaluation
for the spring storm conservatively
maximizes
the potential
snowcover and precipitation.
A limiting
temperature
sequence
that results in an impervious
ground surface due to subfreezing
temperatures
is assumed.
This is followed
byextreme high temperatures,
and a subsequent
major spring storm. The snowmelt
andPage 3 of 11
rainfall
maximizes
the runoff to the river basin. This sequence
of events is postulated
toproduce a PMF. Additional
details regarding
key assumptions
used in the analyses
aredescribed
in USAR Appendix
G.Methodology
Used to Develop Design Basis Flood HazardThe predicted
flood discharge
flow and PMF level at the MNGP site was defined usingDepartment
of the Army, Office of the Chief of Engineers,
the U.S. Army Corps ofEngineers,
Engineer
Circular
No. 1110-2-27,
Enclosure
2, "Policies
and Procedures
Pertaining
to Determination
of Spillway
Capacities
and Freeboard
Allowances
for Dams,"dated August 1, 1966 (Reference
2).The PMF at the MNGP site was determined
by transposing
an actual critical
springstorm to the drainage
basin and maximizing
the precipitation
for potential
moisture.
Potential
snow cover and a critical
temperature
sequence
were developed
fordetermining
snowmelt
contribution
to flood runoff.The study area was divided into four major sub-basins
and synthetic
unit hydrographs
were developed
for each, using Snyder's
method, which is derived from the variousphysical
basin characteristics.
Unit hydrograph
peaks were also increased
by 25 percentand basin lag decreased
by one-sixth,
in accordance
with standard
Corps of Engineerpractice.
Snowmelt
and rainfall
excesses
were applied to unit hydrographs
and the resulting
hydrographs
determined
for each sub-basin.
Sub-basin
hydrographs
were then routed tothe project site by computer
program using the modified
Wilson method. Travel times forflood routing were taken from Corps of Engineers
recorded
travel times for large floods.Base flow was determined
from long-term
records of stream flow for nearby stations.
Base flow was then added to the total of the routed flood hydrographs.
The stage-discharge
curve at the MNGP Site was extended
above the range of historical
experience
by means of hydraulic
computations
based on the river channel downstream.
This was done by a series of backwater
computations
based on a range of discharges.
Backwater
computations
were made using water surface elevations
and theircorresponding
discharges
as determined
from the rating curve downstream
fromMonticello.
Using the discharges
and the resulting
water surface elevations,
a stagedischarge
curve was constructed
for the site.ResultsThe detailed
analysis
results are presented
in USAR Appendix
G. To summarize,
theanalysis
predicts
a probable
maximum discharge
of 364,900 cfs and a corresponding
peak stage of elevation
939.2 ft. msl. The flood would reach maximum river level inabout 12 days after the beginning
of high temperatures,
and it was estimated
the floodstage would remain above elevation
930.0 ft. msl for approximately
11 days.It is noted that the 12 day time period is for the river elevation
to reach the peak level.Other important
levels are the elevation
of the Intake Structure
(919 ft.) and Plant Grade(930 ft.). Based on USAR Appendix
G Exhibits
8 and 9, water elevation
of 919 ft. couldbe exceeded
at about the fourth day and water elevation
of 930 ft. could be exceeded
atthe eighth day.Page 4 of 11
2.2.2 Floods due to Ice Dam Build-UpFlooding
due to backwater,
usually caused by ice jams, was considered.
USAR,Appendix
G, Chapter II, Page G.2-5 states that two types of flooding
occur in the basin --open-water
flooding
and backwater
flooding.
Flooding
while open-water
conditions
prevail is caused by runoff producing
rains, or by melting snow, or by a combination
ofthe two. Flooding
because of backwater
is usually caused by ice jams. The most seriousflooding
throughout
the basin has been associated
with excessive
snowmelt
and rainfall.
Thus, the open-water
flooding
was considered
to be more limiting
that the backwater
flooding,
and was analyzed
in detail in the USAR.3.0 FLOOD MITIGATION
STRATEGYFlood protection
features
and flood mitigation
procedures
are described
below. The PMFevent is applicable
to all modes of operation
(i.e., power operation,
startup,
hotshutdown,
cold shutdown,
and refueling).
Flood Protection
requirements
necessary
toprevent external
flooding
or flood damage to Class I Structures
or Class II structures
housing Class I equipment,
are identified
in USAR Section 12.2.1.7.1.
Flood protection
features
utilized
at MNGP in the event of a PMF include both incorporated
(installed)
andtemporary
active and passive barriers.
MNGP does not rely upon any flood protection
features
external
to the immediate
plant area as part of the current licensing
basis thatprotect safety related systems,
structures
and components
from inundation
andstatic/dynamic
effects of external
floods.Incorporated
engineered
passive or active flood protection
features
are features
that arepermanently
installed
in the plant that protect safety related systems,
structures,
andcomponents
from inundation
and static/dynamic
effects of external
flooding.
Examplesinclude external
walls and penetration
seals that are permanently
incorporated
into aplant structure.
Temporary
passive or active flood protection
features
at MNGP include portable
pumps,sandbags,
plastic sheeting,
steel plates, levees, etc., that protect safety related systems,structures
and components
from the effects of external
flooding.These
features
aretemporary
in nature, i.e., they are installed
prior to design basis external
flood levelsattaining
specific
levels.The following
Class I and II structures
are protected
from flooding
up to 939.2 ft. msl:1. Reactor Building
(including
High Pressure
Coolant Injection
(HPCI) structure)
2. Turbine Building3. Intake Structure
(including
access tunnel)4. Off-gas Stack and Compressed
Gas Storage Building5. Radwaste
Building6. Diesel Generator
Building7. Plant Control and Cable Spreading
Structure
8. Emergency
Filtration
Train (EFT) Building9. Diesel Fuel Oil Pump House10. Diesel Oil Storage TankPage 5 of 11
Flood preparations
at the site begin with a flood surveillance
procedure
(Reference
6).During the time period of interest
the surveillance
was initiated
by procedure
annually
inthe late winter. The procedure
is currently
performed
monthly for river level predictions
and an annual performance
includes
inventory
and inspection
in addition
to the riverlevel prediction.
The purpose of this procedure
is to determine
if the potential
for plantflood exist prior to and during the spring flooding
season to ensure adequate
steps aretaken to protect the plant if the potential
for flooding
exists. The actions taken inReference
6 are summarized
as follows:* Based on the nature of the design basis flood (heavy snow pack,thawing/freezing
cycle, coupled with heavy rain) the flood scenario
is slowdeveloping
and flood levels are generally
predictable.
Reference
6 determines
the potential
for flooding
based on forecast
information
from the NationalWeather Service and river level monitoring.
Procedure
A.6 (Reference
7), Noteto Step 5.2.1, indicates
that the National
Weather Service Flow Exceedance
Probability
Forecast
on internet
is used to forecast
riverelevations.
The information
for the St. Cloud and Anoka measurement
stations
isprovided
on a weekly basis in terms of the probability
that the river flow willexceed a given flow rate. The prediction
information
at the website is for the next90 days based on current conditions.
A flow discharge
curve in Reference
7 isused to determine
predicted
river water elevation
based on the predicted
flowrate. Given the conditions
that precede the PMF; i.e., snowpack
with thawing andrefreezing,
it is reasonable
to expect that the responsible
individuals
at the plant(engineering,
operations,
management)
would be keenly aware of the need tomonitor river water elevations
for predicted
flood conditions.
Increased
monitoring
and use of the predictive
National
Weather Service tools wouldincrease
the time available
to implement
flood protective
actions." Flood preparation
measures
are taken as part of Reference
6 to ensure that floodprotection
materials
such as sandbags,
steel plates, covers and gaskets,
andplugs are available.
Contact information
for vendors that would be used as part offlood preparation
activities
are confirmed
to still be valid. This contact information
includes
vendors that would be involved
with construction
of the bin wall andearthen levee. These actions are implemented
even if flood conditions
are notpredicted.
A memorandum
of understanding
is in place with VeitVeit
& Company,a local construction
firm, to provide construction
related services
in the event of asite emergency,
and would cover activities
such as construction
of the earthenlevee." In the event that the potential
for flood conditions,
dump trucks and excavators
are ensured to be available
for installation
of the levee, and a detailed
flood planis developed.
MNGP Procedure
A.6 (Reference
7), "Acts of Nature,"
(Part 5 -.External
Flooding)
stipulates
the actions to be taken in the event flood waters are predicted
to exceedelevation
918 ft. Revision
41 through Revision
45 of Procedure
A.6 (Reference
7) werein effect during the period of time from February
29, 2012 through February
15, 2013.Revision
41 was issued on February
28, 2012 and Revision
45 was issued on February14, 2013.Page 6 of 11
The following
summarize
the actions in A.6 based on the different
predicted
flood waterelevations.
- Step 5.2.8, river level is predicted
to exceed elevation
918 ft. Notification
ofUnusual Event is declared.
Actions are taken to protect equipment
such as thedischarge
structure
substation.
- Step 5.2.9, river level is predicted
to exceed elevation
919 ft. Actions are taken toprotect the Intake Structure
from flooding.
As noted above the Intake Structure
isat elevation
919 feet.* Step 5.2.10, river level is predicted
to exceed elevation
921 ft. An Alert isdeclared
and the plant is shutdown
and cooled down to cold shutdownconditions.
Actions are taken to ensure a supply of service water is available.
- Step 5.2.11, river level is predicted
to exceed elevation
930 ft. The bin walls andearthen levee are built. Steel plates are installed
on the outside roof areas of theIntake Structure.
Yard drains and other paths that could result in a water pathwaythat bypasses
the levee are closed. An alternate
access route to the plant isprovided
from higher ground in the event that the normal access road is flooded.The levee is designed
to provide flood protection
up to a river elevation
of 941 ft.Backup flood protection
to the levee can be provided
by closing up the variousbuildings
using steel plates, installing
sand bags, etc. It is noted that the levee isidentified
in the procedure
as the preferred
option but, per the procedure,
thebackup flood protection
can be used in lieu of constructing
the levee. This isdiscussed
in more detail below." The remaining
Steps 5.2.12 and 5.2.13 provide additional
backup floodprotection
for predicted
river elevations
above 930 feet. These are backup floodprotection
measures
to the levee.As described
in A.6, Step 5.2.11, Note 2, the preferred
flood protection
measure isconstruction
of a levee around the plant. The decision
to use the levee as the preferred
flood protection
is based on a recommendation
from the US Army Corps of Engineers
(USACE),
letter dated November
8, 2001. This USACE letter is referred
to in the Basesdiscussion
for Part 5 of Reference
7. However,
Reference
7 includes
an option forproviding
flood protection
in lieu of construction
of the levee. This optional
floodprotection
means involves
installing
barriers
(steel plates, etc.), sandbags,
and sealingpenetrations.
Resource
loaded schedules
developed
in support of the A.6 procedure
demonstrate
that the activities
were achievable
in the time required.
Recent simulations
and demonstrations
confirm the construction
time for the bin wall, steel plate installation
and sand bagging.As shown on Figure 13.10 of Reference
7, construction
of the levee includesconstruction
of a bin wall to the immediate
east and west of the Intake Structure.
The binwall was added as part of Revision
41 to A.6 on February
28, 2012. Prior to Revision41, the levee was made entirely
of earthen material.
The decision
to use the bin wall wasbased on an analysis
performed
by Short Elliot Hendrickson,
Inc., (SEH) (Reference
8).As part of this same change, the configuration
of the levee was modified
from a ringlevee entirely
around the plant to a horseshoe
design that ties into areas of the site thatPage 7 of 11
are above the peak PMF water elevation.
The recommendation
to use the bin wall wasmade as part of Reference
8 after considering
various options for the tie to the IntakeStructure.
Reference
8 included
the following
recommendations:
- Secure a borrow source of levee fill within 15 minutes of the site or purchase
andstore on site.* Purchase
bin wall materials,
assemble
in modules to reduce installation
timeframe, and store on site.The deficiencies
identified
in Reference
5 have subsequently
been addressed.
Inaddition
to the noted deficiencies,
other areas were also identified
for improvement
tothe plant and procedures.
All of these areas for improvement
were entered into the plantcorrective
action system.Additional
actions have been implemented
to further improve the flood protection
at thesite. These additional
actions are summarized
below:* Bin wall materials
have been procured
and are now stored on site. Theprocurement
of the bin walls took approximately
eight weeks; however,
this wastreated as a normal procurement.
The bin walls were supplied
by ContechEngineered
Solutions.
Based on discussions
with Contech Engineered
Solutions
it is estimated
that the bin wall sections
could be provided
in approximately
14days in an emergency
situation.
As discussed
above, in the event that the binwalls cannot be constructed
due to unavailability
of materials,
flood protection
could still be provided
as stipulated
in the procedure
using the sandbag and floodbarrier option. This option is independent
of the levee and bin walls.* Levee materials
have been procured
and are now stored on site. Levee materials
were delivered
to the site within four 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> shifts.* External
flood surveillance
procedure,
1478, (Reference
6) has been improved
toincrease
the frequency
of river level monitoring
during potential
floodingconditions.
The additional
river level monitoring
ensures timely plant preparation
for a potential
flood. The increased
river level monitoring
serves to provide earlierwarning of predicted
flood levels and increases
available
time to implement
protective
actions.* Procedure
A.6 (Reference
7) has been revised to improve the procedure
clarity,remove unnecessary
steps, and ensure completeness
of protective
actions." Detailed
work instructions
have been developed
to implement
actions in A.6.The work instructions
provide the technical
detail necessary
to implement
therequired
action. Pre-staging
the work instructions
prior to the event reduces therequired
time frames to implement
the required
actions in A.6.* Monticello
conducted
a self-assessment
of the site flood protection
response
totake an additional
critical
review. The self assessment
was performed
by a teamof Xcel and contract
professionals
experienced
in areas of flood protection.
Page 8 of 11
Specific
areas for improvement
were identified
during the self assessment
andwere entered in the corrective
action program and are being actively
addressed.
4.0 FLOOD MITIGATION
STRATEGY
-FURTHER DEMONSTRATIONS
Table top walkthroughs
of procedure
A.6 have been performed
to demonstrate
feasibility
of performance
of the required
actions.
A detailed
schedule
is developed
for the actionsin A.6 using input from the site departments
who would execute the actions.
Theschedule
shows actions to be performed,
time frames, and sequencing,
anddemonstrates
that the actions can be completed
within the available
time period.Detailed
work instructions
have been developed
to implement
the actions in A.6. Pre-staging of the work instructions
reduces the overall time to perform the tasks byremoving
the time associated
with work planning,
identifies
that materials
that may beneeded to accomplish
the work, and identifies
any potential
interferences
orimpediments
to completing
the required
task ahead of time.As described
in Section 3.0, above, the materials
to construct
the bin wall sections
andthe earthen levee have been procured
and are stored on site. As previously
discussed,
amemorandum
of understanding
(MOU) is in place with VeitVeit
& Company,
a localconstruction
firm, to provide equipment
and services
for construction
of the bin wall andearthen levee.Reasonable
simulation
of construction
of several of the actions believed
to be more timeconsuming
was performed
in order to demonstrate
that the actions could be performed
within the available
time frame. Specific
actions examined
were construction
and fillingof the bin walls, construction
of the steel plates around the roof of the Intake Structure,
and filling of sandbags.
The results from these reasonable
simulations
are summarized
below.* Construction
of bin walls. For the reasonable
simulation,
approximately
5% of thetotal bin wall sections
were constructed
and filled. The simulation
was contracted
to Veit to add realism per our MOU and exercise
the mobilization
of personnel.
The reasonable
simulation
took 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> for one crew to fully construct
and fill.Based on using six crews, available
per our MOU, to construct
and fill the binwalls during implementation
of procedure
A.6, this would indicate
that the entirebin wall sections
could be fully constructed
within 1.4 days. Accounting
for issuessuch as excavation,
inclement
weather,
security
concerns,
coordination,
totalconstruction
time of four days is reasonable.
- Steel plates around roof of Intake Structure.
As part of procedure
A.6 steel platesare attached
to the wall of the Intake Structure
with anchors and the seamsbetween the plates welded to form part of the flood protection
barrier.
For thereasonable
simulation,
approximately
20% of the plates were installed
on amock-up.
The reasonable
simulation
took 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> and 11 minutes.
Based on onewelder all of the plates could be installed
within 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />. Using two welderswould reduce this time to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. Additional
welders would reduce this timeeven more. This time period is much less than the available
time and providesmargin for working in inclement
weather conditions.
Page 9 of 11
Sandbagging.
Per procedure
A.6, approximately
100,000 sandbags
are filled.Sandbags
are used in several steps in A.6 to seal openings,
provide backupflood protection.
Sandbags
are critical
in the event that the sandbag and floodbarrier option were implemented
in A.6 in lieu of the levee option. Reasonable
simulation
indicates
that 600 sandbags
can be filled per hour using one machineand 8 people. Go-Baggers
are a manual bagging apparatus
with which anindividual
can fill 55 bags an hour. With one machine and 20 people workingaround the clock, the 100,000 sandbags
can be filled in 2 1/2 days. Reasonable
simulation
also showed that a steel double door can be sandbagged
by fivepersonnel
in 34 minutes.
Furthermore,
it was shown that laying lumber andsandbagging
1 EDG room can be accomplished
by 14 personnel
in four hours.In the three cases discussed
above, the reasonable
simulation
concluded
that therequired
actions can be accomplished
within the available
time frame.5.0 CONCLUSIONS
The following
conclusions
are drawn from the above discussion:
- The postulated
flood scenario
for the MNGP is considered
to be veryconservative.
The methodology
employed
provides
conservative
results.
Thiscan be seen from the comparison
of river flow rates and water elevations
inTable 1 in Section 2.1, above.* The flood is a relatively
slow developing
evolution
that allows time for plant staffto monitor,
predict and implement
appropriate
actions to provide the requiredflood protection.
- The flood mitigation
procedure
clearly identifies
actions for plant staff toimplement
to provide the required
flood protection.
- In the event that the levee were not able to be constructed
due to not having thebin wall materials
available,
the procedure
provides
an optional
approach
toimplement
flood protection
without relying on the levee and bin wall system.Table top review of the steps to implement
this optional
means of floodprotection
demonstrated
that the protection
could be provided
within theavailable
time.* Subsequently
actions have been taken to procure the bin wall and leveematerials.
Reasonable
simulation
has demonstrated
that the levee and bin wallsystem can be installed
well within the available
time.Page 10 of 11
6.0 REFERENCES
1. Monticello
Nuclear Generating
Plant, Updated Safety Analysis
Report (USAR), Revision
29.2. Department
of the Army, Office of the Chief of Engineers,
the U.S. Army Corps ofEngineers,
Engineer
Circular
No. 1110-2-27,
Enclosure
2, "Policies
and Procedures
Pertaining
to Determination
of Spillway
Capacities
and Freeboard
Allowances
for Dams,"dated August 1, 1966.3. NRC Letter to Licensees,
dated March 12,2012,
"Request
for Information
Pursuant
to Title10 of the Code of Federal Regulations
50.54(f)
Regarding
Recommendations
2.1,2.3,
and9.3 of the Near Term Task Force Review of Insights
from the Fukushima
Daiichi Accident"
(ADAMS Accession
No. ML 12053A340).
4. NEI 12-07, Revision
O-A, "Guidelines
for Performing
Verification
Walkdowns
of Plant FloodProtection
Features,"
dated May 2012 (ADAMS Accession
No. ML 12173A215).
5. Xcel Energy Letter L-MT-1 2-097, "MNGP Final Response
to NRC Request for Information
Pursuant
Regarding
the Flooding
Aspects of Recommendation
2.3 of theNear-Term
Task Force Review of Insights
from the Fukushima
Dai-ichi
Accident,"
datedNovember
27, 2012.6. Procedure
1478, "External
Flood Surveillance,"
Revision
7. [Revision
7 is the procedure
revision
currently
in effect. During 2012, Revisions
4 through 6 was in effect and theprocedure
was titled "Annual Flood Surveillance."]
7. Procedure
A.6, "Acts of Nature,"
Revision
46. [Revision
46 is the procedure
revisioncurrently
in effect. When used, previous
revision
numbers are identified
in the text.]8. Xcel Contract
No. 38398, SEH No. MONNE 117980, "Monticello
Nuclear Generation
Plant,External
Flooding
Plan Update: Alternative
Analysis
and Final Design Report,"
datedJanuary 5, 2012.Page 11 of 11
Enclosure
4Monticello
Nuclear Generating
Plant"Annual Exceedance
Probability
Estimates
for Mississippi
River Stages at theMonticello
Nuclear Generating
Plant based on At-site Data for Spring and SummerAnnual Peak Floods"12 Pages Follow
Annual Exceedance
Probability
Estimates
for Mississippi
River Stages at the Monticello
NuclearGenerating
Plant based on At-site Data for Spring and Summer Annual Peak FloodsDavid S. Bowles and Sanjay S. ChauhanRAC Engineers
& Economists
June 28, 2013Purpose:To estimate
the annual exceedance
probabilities
(AEPs) for Mississippi
River Stages 917, 930 and 935 ft.NGVD 29 at the Monticello
Nuclear Generating
Plant (MNGP) using at-site data for spring and summerfloods.These estimates
are intended
to improve on the previous
annual peak flood estimates
that weresubmitted
on April 8, 2013. The previous
estimates
were was based on an at-site flood frequency
curveconstructed
using a) a conservatively
assigned
AEP to the Harza spring PMF, and b) at-site floodfrequency
estimates
obtained
from a drainage-area
weighted
interpolation
between provisional
USGSannual peak flood frequency
estimates
for the upstream
and downstream
River gages at St.Cloud and Elk River, respectively.
Given more time, we recommend
that a Monte Carlo rainfall-runoff
approach
should be used to developestimates
of extreme flood frequencies
to make use of regional
precipitation
data and a morephysically-based
transformation
of rainfall
to runoff, including
snow melt and explicit
consideration
ofuncertainties.
Available
Information:
Observed
mean daily flows at the following
locations:
1) Station Number 05270700
River at St. Cloud, MN with a period of record from 1989to 2012.2) Station Number 05275500
River at Elk River, MN with a period of record from 1916to 1969.3) Monticello
Nuclear Generating
Plant (at-site)
with a period of record from 1970 to 2012.Flood frequency
estimates
of annual peak discharges:
4) Provisional
2013 USGS annual peak discharge
flood frequency
analyses
with estimates
of AEPsranging from 1 in 1.005 to 1 in 500 based on maximum daily flow rates for the annual peakflows:1
a. Station Number 05270700
River at St. Cloud, MN with drainage
area of13,320 sq. miles.b. Station Number 05275500
River at Elk River, MN with drainage
area of14,500 sq. miles.Probable
maximum flood (PMF) peak discharge
and stage estimates:
5) Harza 1969 (spring)
PMF peak discharge
and river stage at the Monticello
Nuclear Generating
Plant -1912 Datum.6) Bechtel 20121 spring and summer PMF peak discharges
and river stages at the Monticello
Nuclear Generating
Plant -NAVD88 Datum.Discharge
rating relationships:
7) Harza 1969 relationship
between river stage (1912 Datum) and river discharge
(cubic feet persecond, cfs) over the range 26,000 to 437,000 cfs.8) Ops manual equation
between river discharge
(cubic feet per second, cfs) up to 4,000 cfs andriver stage (NGVD 29 Datum): Q = 122(Stage
-901)2.2.Datum conversions
for river stages:9) NGVD 29 Datum = 1912 Datum -0.36 ft.10) NGVD 29 Datum = NAVD 88 Datum -0.4 ft.Procedure:
The following
two approaches
were examined
for developing
improved
at-site estimates
of annualexceedance
probabilities
(AEPs) for the spring and summer annual floods in the Mississippi
River at theMNGP:1) Drainage-area
weighted
interpolation
of flood frequency
estimates
for the upstream
anddownstream
USGS gages: Similar to the April 8, 2013 approach,
an at-site flood frequency
curvewas obtained
from a drainage-area
weighted
interpolation
between flood frequency
estimates
for the upstream
and downstream
River gages at St. Cloud and Elk River,respectively.
However,
this revised approach
was conducted
separately
for spring and summerannual peak floods and it did not conservatively
assign an AEP to the Harza PMF as was done inthe April 8, 2013 approach.
Instead the flood frequency
curve was extrapolated
to extremefloods thus providing
estimate
of the AEPs for the spring and summer PMF peak flow estimates
and for the three elevations
of interest.
1 The report, Bechtel 2012 spring and summer PMF peak discharges
and river stages at the Monticello
NuclearGenerating
Plant -NAVD88 Datum, has been provided
to NSPM. This study provides
bounding
estimates
to sitepeak flood elevations
applicable
to the development
of annual exceedance
probabilities
at the Monticello
NuclearGenerating
Plant.2
2) Flood frequency
analysis
based on at-site flow data: A flood frequency
analysis
was conducted
on the available
at-site streamflow
data for the period 1970 to 2012 with extrapolation
toextreme floods. This provided
estimate
of the AEPs for the three elevations
of interest
and forthe PMF peak flow estimates
for spring and summer annual peak floods.Both of the above approaches
included
estimating
separate
flood frequency
relationships
for spring andsummer annual peak floods. Data for estimating
these relationships
were obtained
using the following
definitions
of spring and summer floods based on discussions
in the Hydrologic
Atlas of Minnesota
(Stateof Minnesota
1959) and examination
of the flow records:1) Spring annual peak floods generally
peaked in the period March to May, but if it was clear fromexamination
of the hydrograph
that a snow melt flood event peaked in June then that peak wasused.2) Summer annual peak floods generally
peaked in the June to early October period, but floodpeaks occurring
in June, which were clearly associated
with snow melt events, were excluded
asmentioned
in 1). Since the recession
limb of the annual snow melt hydrograph
extends throughthe summer, the peak flow rates for summer floods, which are associated
with convective
storms, are dependent
to some degree on the magnitude
of flow on this recession
limb at thetime of the summer flood.The two approaches
are discussed
in more detail below.Approach
1): Drainage-area
weighted
interpolation
of flood frequency
estimates
for the upstream
anddownstream
USGS gagesThe provisional
USGS annual peak flow flood frequency
estimates
for the Mississippi
River gages at St.Cloud and Elk River were verified
using USGS flood frequency
software
following
Bulletin
- 17B floodfrequency
analysis
procedures
(USGS 1982). The following
softwares
were applied to the maximumdaily annual peak streamflow
data assembled
by the USGS to verify their results:1) PeakFQ: Bulletin
- 17B procedure
based on method of moments parameter
estimation
for a LogPearson Type 3 probability
distribution
(Flynn et al 2006)2) PeakfqSA:
The more efficient
Expected
Moments Algorithm
(EMA) applied to the Bulletin
- 17Bmethodology
(Cohn 2012)Following
the USGS provisional
analysis,
the Bulletin
- 17B (PeakFQ)
software
was applied to the St Cloudgage and the EMA (PeakfqSA)
software
was applied to the Elk River gage for the verification
step.Separate
flood frequency
analyses
were then conducted
for spring and summer annual peak flow dataat the St. Cloud and Elk River USGS gages. The maximum daily annual peak streamflow
data wereassembled
by the USGS and provided
with their provisional
flood frequency
analyses.
These datacomprised
a mixture of spring and summer floods. These data were separated
into spring and summerfloods and mean daily peak flow data were obtained
from USGS flow records at both gages for thosecases that were not covered by the maximum daily annual peak streamflow
data assembled
by the3
USGS. An additional
year (2012) of data was added for the St Cloud gage. Maximum daily annual peakflows were estimated
from mean daily annual peak flows for those data not included
in the USGSprovisional
analyses
using regression
relationships
established
between maximum daily annual peakflow data and mean daily annual peak flow data for spring and summer flows for each gage.The PeakfqSA
software
containing
improved
EMA parameter
estimation
(Stedinger
2013) was applied toboth spring and summer flood data for both gages. No outliers
were identified.
The EMA softwareprovided
AEP estimates
from I in 1.0001 to I in 10,000. Estimates
of annual peak discharge
on theMississippi
River at the MNGP were then obtained
based on linear interpolations
between variousfrequency
(AEP) estimates
developed
for the St Cloud and Elk River gages as a function
of drainage
areawith the drainage
area at the MNGP being 14,071 sq. miles. This interpolation
the procedure
is thesame as developed
for the April 2013 AEP estimates.
The at-site annual peak discharge
estimates
wereconverted
to at-site river stages using a combination
of the Harza and Ops Manual equation
ratingcurves shown in Figure 1.Examination
of the relationship
between flood estimates
for various AEPs and drainage
area shown inFigure 2 showed an inconsistent
relationship
that was increasing
or decreasing
with drainage
area. As aresult we have not relied on these estimates
in favor of using the flood frequency
estimates
obtainedfrom analysis
of at-site data in the second approach.
947942937* 9320JS927 _______.5922 __________
0JS917912907 1 1 _________
9021100 1,000 10,000 100,000 1,000,000
Discharge
In cfs-Ops Man Eqn, Q= 122(Stage-901)^2.2
-Harza Discharge
Rating -- Transition
-.Final curveFigure 1. Combined
Harza and Ops Manual Equation
stage-discharge
rating curve4
80,00070,00060,00050,0000 40,000E.30,00020,00010,000Interpolation
of at-site quantiles
-TFU-------- ----- ----*0.995-0.99-0.95-0.9.--0.6667ý0.5--*-0.4292-o-0.2-0.04-0.02-.--0.01-0-0.005-4-0.002-MNGS5,000U13,00013,50014,000Drainage
Area (sq. miles)14,600IFigure 2. Relationships
between flood estimates
for various AEPs and drainage
area for Approach
1Approach
2): Flood frequency
analysis
based on at-site flow dataThe second approach
is based on extrapolation
of flood frequency
relationships
developed
from at-siteflow data. The mean daily annual peak stages were obtained
for spring and summer annual peak floodsfollowing
the process summarized
above. Since only single observations
have been recorded
for eachday it was not possible
to obtain maximum daily annual peak stages. The daily annual peak stages wereconverted
to daily annual peak flows for spring and summer floods using the combined
rating curveshown in Figure 1. The EMA (PeakfqSA)
software
was applied to estimate
the flood frequency
relationships
for spring and summer annual peak floods. No outliers
were identified
for the springseason, but one low outlier (2,416 cuffs) was identified
for the summer season using the MultipleGrubbs-Beck
Test) low outlier identification
method. The EMA software
provided
AEP estimates
for therange 1 in 1.0001 to 1 in 10,000.Annual Exceedance
Probability
Estimates:
Figures 3 and 4 show the resulting
flood frequency
estimates
for the spring and summer annual peakfloods obtained
from the second approach.
The annual peak discharge
is plotted on a Log scale andAEPs are plotted on a z-variate
scale (corresponding
to a Normal probability
distribution).
In addition
to5
Monticello
NGS -Spring1,000,000
B el 2012 PMF estim tean--- ----a--T9. nbrPes-Tma
--e .--., e.0l vafion 93SEl, -atlon 930100,000 ...... ...-, -..-'":! ...
""h...=-- -- ~ ~... :...........
10,000 v-Exce dance Probability
1E I 1E-1 1E-2 E-3 1E-4 iE-5 1E-6 1E-7 1E-8 1 91,000 .I I I" I 1- 1-4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0z-variate
Figure 3. Spring Annual Peak Flood Frequency
(approximate
mean shown by black dashed line)6
Monticello
NGS -Summer1,000,000
N024)4)4)a.100,00010,0001,000-4.0 -310 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0z-variate
Figure 4. Summer Annual Peak Flood Frequency
(approximate
mean shown by black dashed line)7
providing
median (50th percentile)
and approximate
mean2 estimates,
the 20% (40th and 60thpercentiles),
40% (30th and 70th percentiles),
60% (20th and 80th percentiles),
80% (10th and 90thpercentiles),
and 90% (5th and 95th percentiles)
confidence
interval
estimates
are provided
with linearextrapolation
to smaller AEPs beyond 1 in 10,000. The site elevations
of 917, 930 and 935 are shown byhorizontal
lines based on the NGVD 29 datum matching
the datum used on the site drawings.
Also theHarza and Bechtel PMF estimates
are shown by horizontal
lines corresponding
to peak elevations
forthese events.It is noted above that only single daily river stage observations
have been recorded
at site and therefore
it was not possible
to obtain maximum daily annual peak stages. Since the difference
between meandaily and maximum daily peak stages decreases
with smaller AEPs, it is likely that the flood frequency
relationships
are slightly
steeper than shown. This effect would tend to make AEP estimates
forextreme flows slightly
conservative
(i.e. slightly
larger) than of this effect were removed.Tables 1 and 2 contain numerical
AEP estimates
for spring and summer annual peak floods, respectively,
for river stages 917, 930 and 935 ft. NGVD 29 for the median (50th percentile)
and approximate
mean,and for various confidence
percentiles.
Table 1. Spring Annual Peak Flood Frequency
Estimates
Elevation
91795th I ge 1 84th 1 0th I 70th I 60 I Median 50e 5th Approx MeanAEP Estimates
3.4E-02 2.5E-02 2.0E-02 1.7E-02 1.2E-02 8.9E-03 6.3E-03 5.9E-07 7.9E-03i in Tyears 29 40 51 59 82 112 158 1,680,000
127Elevation
93095t' 90 84th 80' 70 60h Median 50 5t Approx MeanAEP Estimates
7.OE-06 7.6E-07 7.5E-08 1.7E-08 < 1E-9 < 1E-9 < 1E-9 < 1E-9 < 1E-91inTyears
143,0001
1,320,0001
13,400,0001
60,500,0001
>1E+9 I >1E+9 [ >1E+9 I >1E+9 [ >1E+9I _Elevation
935F-9 90 o 84th 806 70& 60' Median 506' 51 Approx MeanAEP Estimates
4.3E-07 2.OE-08 < 1E-9 < 1E-9 < 1E-9 < 1E-9 < 1E-9 < 1E-9 < 1E-91 in T years 2,350,000
51,100,000
>1E+9 >1E+9 >1E+9 >1E+9 >1E+9 >1E+9 >1E+9Table 2. Summer Annual Peak Flood Frequency
Estimates
___Elevation
9179Sth 90t 84th 80 th 70 th 60d Median 50th 5th Approx MeanAEP Estimates
1.9E-02 1.3E-02 8.8E-03 7.2E-03 4.4E-03 2.8E-03 1.7E-03 8.5E-07 3.OE-031 in Tyears 52 79 113 140 225 358 590 1,180,000
328_ _Elevation
930_95_ 90go 84th 80eh 70th 60e Median 506h 5th Approx MeanAEP Estimates
2.1E-04 4.3E-05 8.8E-06 3.1E-06 2.4E-07 1.5E-08 < 1E-9 < 1E-9 1.6E-061in Tyears 4,7201 23,4001 11,00 324,000 4,160,000
65,100,000
>1E+9 >1E+9 641,000I-_ Elevation
93595h 90 o 841 80h 70 60'h Median 50' 5 h Approx MeanAEP Estimates
6.1E-05 7.9E-06 9.7E-07 2.5E-07 8.9E-09 < 1E-9 < 1E-9 < 1E-9 2.OE-07I in T years 16,500 127,000 1,030,000
4,000,000
112,000,000
>1E+9 >1E+9 >1E+9 1 4,930,000
2 The approximate
mean estimates
were obtained
by weighting
the various percentile
estimates
by theirrespective
intervals
of probability
that each represents.
For example,
the 60th percentile
represents
the intervalbetween the mid-points
of the 50th -60th and 60th -70th percetile
intervals
and hence is weighted
by thedifference
between the percentiles
associated
with the mid-points
of these two intervals,
i.e. 0.65-0.55
= 0.10.8
The following
is a summary of the median estimates
and ranges (Upper -95th percentile
and Lower -5thpercentile)
of the AEP estimates
for the river stages of 917, 930 and 935 ft. NGVD 29 at the Monticello
Nuclear Generating
Plant for spring and summer annual peak floods and for the Harza and Bechtel PMFestimates.
The April 8, 2013 spring estimates
are shown in italics for comparison.
The comparison
shows that these estimate
were conservative
relative
to those obtained
using the second approach.
Spring Floods:Elevation
917 ft. NGVD 29:* Upper (95th): 3.4E-02 (1 in 29/year)
4.OE-02 (1 in 25/year)" Median (50th): 6.3E-03 (1 in 158 /year) 7.2E-03 (1 in 140/year)
- Lower (5th): 5.9E-07 (1 in 1,680,000
/year) 9.5E-04 (1 in 1,100/year)
Elevation
930 ft. NGVD 29:* Upper (95th): 7.OE-06 (1 in 143,000 /year) 1.6E-04 (1 in 6,300/year)
- Median (50th): < 1E-9 (1 in >1E+9 /year) 1.6E-05 (1 in 61,000/year)
- Lower (5th): < 1E-9 (1 in >1E+9 /year) 2.2E-06 (1 in 460,000/year)
Elevation
935 ft. NGVD 29:* Upper (95th): 4.3E-07 (1 in 2,350,000
/year) 3.OE-05 (1 in 33,000/year)
- Median (50th): <1E-9 (1 in >1E+9 /year) 3.1E-06 (1 in 330,000/year)
- Lower (5th): <1E-9 (1 in >1E+9 /year) 3.4E-07 (1 in 2,900,000/year)
The Harza Spring PMF AEP estimates
are shown below with the April 8, 2013 AEPs assigned
to the Harza(spring)
PMF shown in italics for comparison.
- Upper (95th): 5.9E-08 (1 in 16,900,000)
1 in 10,000,000
- Median (50th): < 1E-9 (1 in >1E+9 /year) 1 in 1,000,000
" Lower (5 h): <1E-9 (1 in >1E+9 /year) 1 in 100,000The estimates
of AEPs assigned
to the Harza PMF in the April 8, 2013 work are therefore
confirmed
tobe conservative
(i.e. larger than now estimated).
The AEP Bechtel spring PMF estimates
are shown below:" Upper (95th): 1.8E-08 (1 in 54,500,000)
Summer Floods:Elevation
917 ft. NGVD 29:* Upper (95th):* Median (50th):* Lower (5th):1.9.4E-02
(1 in 52 /year)1.7E-03 (1 in 590 /year)8.5E-07 (1 in 1,180,000
/year)Elevation
930 ft. NGVD 29:* Upper (95th):* Median (50th):" Lower (5th):2.1E-04 (1 in 4,720 /year)< 1E-9 (1 in >1E+9 /year)<1E-9 (in >1E+9/year)
Elevation
935 ft. NGVD 29:000Upper (95th):Median (50th):Lower (5th):6.1E-05 (1 in 16,500 /year)< 1E-9 (1 in >1E+9 /year)< 1E-9 (1 in >1E+9/year)
The AEP Bechtel summer PMF estimates
are shown below:* Upper (95th):* Median (50th):* Lower (5th):5.7E-04 (1 in 1,750/year)
3.3E-08 (1 in 29,900,000
/year)< 1E-9 (1 in >1E+9/year)
The second approach
used to develop these revised AEP estimates
is preferred
to the initial approachused to develop our April 2013 estimates
for the following
reasons:1) It separates
the spring and summer flood events.2) It relies on at-site date rather than a drainage-area
weighted
interpolation
of AEP estimates
atupstream
and downstream
River USGS gages.3) It does not rely on an assignment
of an AEPtothe
PMF.A graphical
comparison
of the April 2013 and the current estimates
is presented
in Figure 5. It indicates
that the April 2013 AEP estimates
are likely overly conservative
as a result of the assignments
of theAEPs to the Harza PMF.Figure 5 is similar to Figure 3 but includes
the USNRC (2013) AEP estimates:
9.37E-05
for Elevation
930and 2.72E-05
for Elevation
935 (based on 6.65E-05/year
for Elevation
930-935).
The NRC estimates
exceed our current 95th percentile
estimates
but are very similar to our April 2013 95th percentile
estimates,
which were based on assigning
an AEP of 1E-5 to the Harza PMF. According
to USNRC (2013)their estimates
are based on flood frequency
estimates
from the Monticello
USAR and IPEEE but we arenot clear about the origin of those estimates
or the curve fitting approach
that was used by the USNRC(2013). Therefore
it is not possible
to make a more informed
comparison
with our estimates;
although
it10
Monticello
NGS -Spring1,000,000
z99LaJtU.X100,00010,0001,000-4.0-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0z-variate
-April 2013 Best Estimate
--April 2013 Upper Estimate
--April 2013 Lower Estimate
- NRC Estimates
-Approx Mean6.0Figure 5. Comparison
of the current Spring Annual Peak Flood Frequency
with the April 2013 estimates
and the NRC (2013) estimates
11
would appear that our estimates
rely on more recent site-specific
data than the NRC had available.
Inaddition
they use the Bulletin
- 17B flood frequency
approach,
which is the standard
for flood frequency
analysis
in the US. We also used the improved
EMA parameter
estimation
approach
that will beincluded
in the revision
of the Bulletin
- 17B procedure
that has been drafted.However,
we recommend
that a Monte Carlo rainfall-runoff
approach
be considered
to developestimates
of extreme flood frequencies
with explicit
consideration
of uncertainties
in the future. Thisapproach
can be expected
to provide improved
estimates
based on the use of regional
rainfall
analysis,
and a more physics-based
representation
of the rainfall-runoff
(including
snow melt) processes
forextreme floods than is associated
with the current extrapolation
approach.
References
Cohn, T. 2012. User Manual for Program PeakfqSA
Flood-Frequency
Analysis
with the ExpectedMoments Algorithm
DRAFT. September.
Flynn, K.M., Kirby, W.H., and Hummel, P.R., 2006, User's Manual for Program PeakFQ Annual Flood-Frequency
Analysis
Using Bulletin
17B Guidelines:
U.S. Geological
Survey, Techniques
andMethods Book 4, Chapter B4; 42 pgs.State of Minnesota.
1959. Hydrologic
Atlas of Minnesota.
Davison of Water, Department
ofConservation,
State of Minnesota.
Stedinger,
J.R. V. Griffis,
A. Veilleux,
E. Martins,
and T. Cohn. 2013. Extreme Flood Frequency
Analysis:
Concepts,
Philosophy
and Strategies.
Proceedings
of the "Workshop
on Probabilistic
FloodHazard Assessment
(PFHA)" sponsored
by the U.S. Nuclear Regulatory
Commission's
Offices ofNuclear Regulatory
Research,
Nuclear Reactor Regulation
and New Reactors
in cooperation
withU.S. Department
of Energy, Federal Energy Regulatory
Commission,
U.S. Army Corps ofEngineers,
Bureau of Reclamation
and U.S. Geological
Survey organized.
Rockville,
January 29 -31.USGS (US Geological
Survey).
1982. Guidelines
for Determining
Flood Flow Frequency.
Bulletin
- 17B,Hydrology
Subcommittee,
Interagency
Advisory
Committee
on Water Data, Office of Water dataCoordination.
USNRC (U.S. Nuclear Regulatory
Commission).
2013. Monticello
Nuclear Generating
Plant, NRCInspection
Report 05000263/2013008;
Preliminary
Yellow Finding.12
Enclosure
5Monticello
Nuclear Generating
Plant"Stakeholder
Outreach"
I Page Follows
Stakeholder
OutreachNSPM hosted an open house on Thursday,
June 6, from 4 p.m.-8 p.m. to shareinformation
with its community
neighbors
on operations
and preparedness
to handlepotential
emergencies
and how we would respond to flooding,
and otherunforeseen
challenges.
The Site employed
numerous
methods to publicize
the event:personal,
direct invitations
to community
leaders,
a full page ad was purchased
inweekly newspapers,
a news release was distributed
to local media and 14,000postcards
were mailed to neighbors
in surrounding
communities.
The outreach
eventhad full corporate
support and the Xcel Energy Chairman,
President
and CEO, and theChief Nuclear Officer attended,
as well as numerous
senior members of the corporate
nuclear staff. The Monticello
Site Vice President
and Plant Manager were also joined bythe site's senior leadership
team at the event.A total of 515 persons from Monticello
and surrounding
communities
attended
the eventat the Monticello
Training
Center.The key message presented
to visitors
was that safety and security
at the NSPM nucleargenerating
plants are top priorities
for Xcel Energy. Further,
that we understand
theNRC's increased
scrutiny
of safety and flood preparedness
at the nation's
nuclear powerplants in the wake of events such as 9/11 and Fukushima
Daiichi.
The Monticello
FloodProtection
Strategy
was identified
and explained
to demonstrate
that the site is designedto withstand
a hypothetical
flood beyond anything
reported
in the Monticello
area. Thebroad underlying
key messages
were reinforced
and manifest
in specific
subject itemssuch as: B.5.b Pump/Electrical
Generator/Trailer,
Portable
Emergency
ResponseEquipment,
Backup Power Sources including
description
of backups to the backup(Battery
Systems)
and the continual
focus on improving
emergency
preparedness
capabilities.
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