ML13197A118
| ML13197A118 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 07/15/2013 |
| From: | Meyer L Point Beach |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| EA-13-125, IR-13-011, NRC 2013-0069 | |
| Download: ML13197A118 (45) | |
See also: IR 05000266/2013011
Text
July 15, 2013 U.S. Nuclear Regulatory
Commission
ATTN: Document Control Desk 11555 Rockville
Pike Rockville, MD 20852 Point Beach Nuclear Plant, Units 1 and 2 Dockets 50-266 and 50-301 Renewed License Nos. DPR-24 and DPR-27 NEXT era POINT BEACH NRC 2013-0069
Supporting
Documentation
for July 22. 2013. Regulatory
Conference
to Discuss Inspection
Report 05000266/2013011
and 05000301/2013011.
Preliminary
Yellow Finding References:
1) U.S. Nuclear Regulatory
Commission, Point Beach Nuclear Plant, Units 1 and 2 NRC Integrated
Inspection
Report 05000266/2013011
and 05000301/2013011;
Preliminary
Yellow Finding, dated June 18, 2013. (ML 13169A212)
2) Point Beach letter NRC-2013-0054
Response to Inspection
Report 050000266/2013011;
Preliminary
Yellow Finding, dated June 28, 2013. (ML 13179A333)
On June 18, 2013, the Nuclear Regulatory
Commission (NRC) provided NextEra Energy Point Beach, LLC (NextEra)
with the results of the Temporary
Instruction (TI) 2515-187, "Inspection
of Near-Term
Task Force Recommendation
2.3 Flooding Walk Downs," conducted
at the Point Beach Nuclear Plant (PBNP) during the first quarter of 2013, describing
a performance
deficiency
related to the PBNP implementation
of certain procedures
intended to mitigate postulated
flooding events (Reference
1 ). The Reference
1 letter further informed NextEra that NRC had preliminarily
determined
that the significance
of the identified
performance
deficiency
was yellow. On June 28, 2013, NextEra requested
a Regulatory
Conference
to discuss the significance
determination (Reference
2). The requested
Regulatory
Conference
has been scheduled
for July 22, 2013. NextEra has thoroughly
reviewed the issue raised in the Reference
1 letter, and has concluded
that the Individual
Plant Examination
for External Events (IPEEE) contains estimates
and assumptions
that are overly conservative
and it is not appropriate
to use in the safety significance
determination
for this performance
deficiency.
Therefore, NextEra has performed
substantial
additional
analyses utilizing
more recent best-available
information
and modeling to more accurately
determine
the potential
safety significance
of the identified
performance
deficiency.
Using the updated external flooding analysis and Probabilistic
Risk Assessment
NextEra Energy Point Beach, LLC, 6610 Nuclear Road, Two Rivers, WI 54241
Document Control Desk Page 2 (PRA) models of the effects of postulated
flooding is the correct tool for assessing
the safety significance
of the performance
deficiency
.. The results of the updated analyses clearly demonstrate
that the safety significance
of the performance
deficiency
is very low. As requested
in Reference
1, NextEra has provided both a summary description
of the updated analyses and an explanation
of the results in the Enclosure
to this letter. Attachment
1 conta i ns the updated wave run-up analysis performed
by NextEra's independent
contractor.
Attachment
2 is an updated safety significance
determination
analysis showing that the safety significance
of the performance
deficiency
is very low, with margin. Attachment
3 prov i des an explanation
of the PBNP design, showing that the r unning Service Water pumps would continue to operate following
a loss of DC control power. Finally, Attachment
4 is an analysis of the rates of rise of Lake Michigan during various postulated
flooding events, showing that PBNP would have more than eight weeks to respond to pre-storm
level changes before the station's license basis flood level would occur. NextEra looks forward to discussing
these documents, together with our assessment
of the very low safety significance
of the performance
deficiency , in greater detail during the upcoming Regulatory
Conference. This letter contains no new Regulatory
Commitments
and no revisions
to existing Regulatory
Commitments.
If you have any questions
or require additional
information, please contact Mr. Ron Seizert , Licensing
Supervisor
at (920)755-7500.
Very truly yours, NextEra Energy Point Beach, LLC L c Site Vice President
Enclosure
cc: Administrator , Region Ill, USNRC Project Manager, Point Beach Nuclear Plant, USNRC Resident Inspector, Point Beach Nuclear Plant, USNRC Branch Chief, Plant Support, Division of Reactor Safety, Region Ill, USNRC
ENCLOSURE
NEXTERA ENERGY POINT BEACH, LLC POINT BEACH NUCLEAR PLANT UPDATED FLOODING ANALYSIS AND SIGNIFICANCE
DETERMINATION
Executive
Summary The NRC preliminary
significance
determination
for the performance
deficiency (Reference
1) was based on determining
the change in Core Damage Frequency (CDF) using the Individual
Plant Examination
of External Events (IPEEE). NextEra has developed
an updated , more accurate storm surge/wave
run-up analysis which provides a more reliable analytical
basis for assessing
the associated
safety significance
of the postulated
flooding event. The application
of this more accurate approach shows that the identified
performance
deficiency
is of very low safety significance, with margin. Description
of the Updated Flooding Analysis and Resulting
Significance
Determination
The external flooding analysis for Point Beach Nuclear Plant (PBNP) contained
in the station's
IPEEE is dominated
by overly conservative
estimations
and assumptions.
These estimations
and assumptions
include the resultant
water elevations, environmental
conditions, equipment
elevations, and site configuration
and topography.
The cumulative
effect of these overly conservative
assumptions
results in significantly
overestimating
the impact of external flooding events, including
wave run-up. In order to better determine
the safety significance
of the identified
performance
deficiency, NextEra retained an expert independent
engineering
firm to update the station's
external flooding analysis utilizing
more recent and more accurate data. The updated analysis assumes the same initiating
still water level frequencies
as those used in the IPEEE. Further, the updated analytical
model utilizes actual plant structures, configuration, topography, and near-shore
bathymetric
survey data in calculating
the range of water levels and associated
wave run-up conditions.
The updated model included no off-setting
credit for any of the flood/wave
run-up mitigation
actually in place at PBNP to determine
water levels outside of the Turbine Building.
The calculated
water level provides the effective
driving head for any potential
water intrusion
into the Turbine Building.
NextEra performed
analysis of the potential
water flow paths in the Turbine Building to determine
the time it takes to accumulate
sufficient
water to impact safety significant
equipment.
A computer model was used to conduct this analysis, based on plant flow paths and rates, which were validated
by walk-downs. Water flow rates were determined
by calculating
flow under doors, over curbs, and through other building characteristics. It would take greater than three hours for water outside the turbine building to impact the Residual Heat Removal (RHR) Pumps and their suction valves from Containment
Sump B. However, for the purpose of simplification
and to build additional
margin into the analysis, the water was assumed to reach equilibrium
inside and outside the buildings
at time zero for the purpose of determining
impact to equipment.
Finally, the calculated
water level outside the Turbine Building was used as an input to the PBNP Probabilistic
Risk Assessment (PRA) to evaluate the risk significance
of the postulated
Page 1 of 8
flooding/wave
run-up scenarios.
This updated risk significance
determination
assumed that the external flooding wave run-up protection
mitigation
features described
in the PBNP Final Safety Analysis Report (FSAR) were not in place. The resulting
significance
determination, using the updated analysis and conservative
assumptions
described
above, demonstrate
that the safety significance
of the performance
deficiency
is very low, with margin. Evaluation
of Flood/Wave
Run-Up, Water Levels and Potential
Equipment
Impacts The PBNP external flooding analysis had been updated to more accurately
predict the potential
flooding/wave
run-up impact on PBNP and the result of the revised analysis was used to assess the potential
impact of the calculated
water levels on plant equipment.
The equipment
impact analysis utilizes the same initial conditions
contained
in the FSAR, updated to include actual site topography, offshore bathymetry
and the as-built shore-line
configuration
to calculate
expected wave phenomena
at various lake levels, including
those of very long recurrence
intervals (e.g., high lake levels). The resultant
wave phenomena
were then used as input data for the DELFT3D computer model, a state of the art model that can simulate both two dimensional (in either the horizontal
or vertical plane) and three dimensional
flow, to analyze Lake Michigan behaviors
during external flooding events and to determine
the resulting
effect of wave run-up at PBNP. The DELFT3D model has been accepted by industry experts and industry organizations
including
more than 70 countries
world-wide that use DEL TARES hydrology
modeling programs and is being used extensively
for post-Fukushima
flood hazard analyses.
The DELFT3D model has also been recently used by several other nuclear plants to demonstrate
compliance
with NRC requirements, including:
- South Texas Project, Units 3 and 4 COLA and FSAR (Delft3D-FLOW) for breach and wave modeling * Turkey Point Units 6 and 7 (Delft3D-FLOW), tsunami wave analysis * Turkey Point Units 3 and 4 flood hazard reevaluation
- Nine Mile Point (NMP) (DELFT-SWAN), for
near shore wave heights and periods * Calvert Cliffs used DELFT for storm surge for COLA and flood hazard reevaluation
- Victoria County Station Early Site Permit Application (Delft3D-FLOW)
for Cooling Basin Breach Analysis Accordingly, NextEra is confident
that its updated engineering
evaluation
of potential
wave run-up effects at PBNP provides the best available
information
to use for safety significance
determinations.
Comparison
of the Updated Storm Surge/Wave
Run-up Analysis to the PBNP IPEEE Analysis The most limiting flooding from Lake Michigan is a function of the still water lake level plus wind generated
waves. To estimate the frequency
of flooding at PBNP, the IPEEE utilized a statistical
frequency
distribution
that was estimated
from Lake Michigan gauge data. This still Page 2 of 8
water lake level has also been used in the updated Storm Surge/Wave
Run-up Analysis (Updated Wave Run-Up Analysis)
as a starting point for the modeling.
However, although the IPEEE utilizes an estimated
wave run-up, it does not describe the estimation
methodology
utilized to determine
its results. It is clear, however, that the IPEEE estimation
methodology
does not take into account site specific shoreline
and near-shoreline
configurations, which are very important
for an accurate determination
of the storm effects. The Updated Wave Run-Up Analysis, on the other hand, utilizes state of the art modeling and analytical
methods, and updated site-specific
input data to determine wave set-up
and wave run-up. Like the IPEEE, the Updated Wave Run-Up Analysis also utilizes conservative
assumptions
for evaluating
the depth of water between the Turbine Building and Pumphouse.
Specifically, both analyses assume the following:
- Yard drains do not contribute
to runoff from flooding.
- There are no relief paths from flooding (e.g., Turbine Building floor drains and Pumphouse
relief paths). The IPEEE utilizes simplified, conservative
estimates
for the amount of water that would accumulate
between the Turbine Building and the Pumphouse
from wave run-up, but again the IPEEE does not describe the estimation
methodology
used to determine
the presented
results. The Updated Wave Run-Up Analysis incorporates
license basis deep water wave heights, more extensive
local and offshore bathymetry, and the as-built shore-line configuration
and characteristics
to calculate
expected wave response at various still water levels. In determining
the equipment
impacted, the internal water levels were assumed conservatively
to equal the calculated
outside water levels at time zero. A comparison
of the overly conservative
IPEEE and the more accurate Updated Wave Run-Up Analysis showing the differences
in calculated
water level between the PBNP Turbine Building and Pumphouse, is presented
below. Summary of Water Levels IPEEE vs. PBNP Updated Analysis Water Level Resulting
Frequency
of Extrapolated
from Calculated Water Water
Level in Still Water Level Still Water the IPEEE Level (With Wave Turbine (ft-IGLD 1955) Level Estimates (ft-Run-up) Building (yr-1) (ft-IGLD 1955) (inches above IGLD 1955) floor) 583.00 1.4E-02 587.60 583.96 0 585.00 3.2E-04 588.37 585.84 0 586.00 5.4E-05 588.73 587.24 0 587.00 4.2E-06 589.24 588.51 3.7" 587.64 9.9E-07 589.53 588.89 8.3" Page 3 of 8
These results demonstrate
that the IPEEE was overly conservative
in estimating
the water level between the Turbine Building and Pumphouse
and is not appropriate
for use in assessing
safety significance
because it is not the best-available
information.
The result of the Updated Wave Run-Up Analysis is appropriate
input to determine
the safety significance
of the performance
deficiency.
The following
Figure shows the levels resulting
from the updated analysis.
Page 4 of 8
Simplified
PBNP Plant Elevation
with Calculated
Water Level (Not to Scale) Turbine Building I PEEE Describes
Lake L evel of 587' and Wave Run-Up to 596' with Frequency
of 4.2E-6. Updated analysis of lake leve l of 587' with wave run-up, results in calculated
water l evel of 588.51'. PU M PHOUSE VSR I EDG 588.2'-Turbine Building Floor 588.51' -Calculated
Water Level @ Turbine Building [ 587'-IPEEE Still Lake ] I 581.9'-Des i gn Bas i s Fl ood 580.7' -I nsta ll Je rs ey B a rri ers 576'-Appro xi m a t e C u rre n t La k e Mich i gan Lev e l Page 5 of 8
Results of the Updated Wave Run-Up Analysis The Updated Wave Run-Up Analysis shows that the calculated
water levels between the Turbine Building and Pumphouse
would be 588.51 feet of water IGLD 1955 for the event frequency
of 4.2E-06/year-much
less severe than estimated
in the IPEEE. The detailed engineering
evaluation
supporting
NextEra's
Updated Wave Run-Up Analysis is provided in Attachment
1. Point Beach Revised External Flood PRA The still water level flood exceedance
frequencies
from the IPEEE were utilized in Next E ra's updated analysis so that the impacts from this updated analysis could be compared to the same flood frequencies
used by the NRC. With the results from the updated external flooding analyses, conditional
core damage probability
was calculated
using the updated RG 1.200 internal events model. Point Beach letter NRC-2013-0054
Response to Inspection
Report 50000266/2013011 (Reference
2) provided a list of potentially
vulnerable
equipment
impacted by accumulating
water up to 589.2 feet (IGLD 1955). NextEra's
updated analysis conservatively
assumed an internal water level of 588.51 feet (IGLD 1955) based on the same calculated
water level outside the Turbine Building.
This internal water level impacts only the Residual Heat Removal (RHR) pumps and RHR pump suction from Containment
Sump B, therefore
this equipment
is not available
in the revised PRA evaluation. Based on the equipment
impacts described
above , the PRA results indicate that the risk due to external flooding (without barriers)
is very low, with a Core Damage Frequency (CDF) equal to 2.83E-07/year. The associated
change in risk with and without barriers was also determined
to be ve r y low, with a change in CDF equal to ?E-09/year.
The NRC's preliminary
significance
determination
of the performance
deficiency
was based on the 1995 Point Beach IPEEE inputs and assumptions.
This determination
calculated
a conditional
core damage probability
of 2. ?E-02/yr.
and a change in CDF of 1.8E-05/yr.
NextEra's
updated analysis demonstrates
that the IPEEE assumptions
of wave run-up levels and final water levels at and in the Turbine Building were overly conservative.
Principle
contributors
to the differences
in overall safety significance
include the site topography, the existing site layout and features, equipment
elevations, and environmental
conditions.
Each of these items has been considered
in the updated detailed modeling described
herein. Attachment
2 provides the supporting
information
associated
with the PRA evaluation.
Continued
Service Water Pump Availability
with Loss of DC Control Power A significant
contributor
to the difference
between the NextEra and the NRC staff estimated
change in CDF with failure of equipment
up to 589.2 feet IGLD 1955 is the PRA modeling of Service Water (SW) pump availability
upon loss of DC control power. NRC's SPAR model contains a presumption
that the SW pump becomes unavailable
upon loss of DC power. Page 6 of 8
The SW pumps remain available
throughout
this event. If operating
at the time DC power is lost, the SW pumps would continue to operate, because DC power is required to open the breaker supplying
AC power to the pumps. In other words, if DC power is lost, the breakers cannot open to turn off the running SW pumps. If the pumps are not operating
at the time DC power is lost, operators
can start pumps by either realigning
DC control power supplies and/or through local manual operation
of their respective
breakers.
Both actions are directed by existing site procedures
upon loss of DC power. The actions for switching
to the alternate
DC control power source and local operation
of SW pumps, including
flow control, are directed by site procedures. These actions were re-validated
by walk-downs with Auxiliary
Operators
and observed by independent
Nuclear Oversight (NOS) observations.
The validation
indicated
that the actions can be completed within one
hour. Finally, these actions are included in Operator training and evaluation
programs.
Attachment
3 provides the supporting
information
associated
with SW pump availability. Lake Michigan Level Rate of Rise Lake Michigan is a very large body of water and changes in level are very slow in comparison
to river level changes. The PBNP original Final Facility Description
Safety Analysis Report (FFDSAR) section discussing
flooding does not address a rate of rise for the lake, so an evaluation
was performed
to establish
the time that is available
to respond to rising lake levels. The rate of rise in lake level was calculated
using National Oceanographic
and Atmospheric
Administration (NOAA) historical
lake data for the 95 year period from 1918 through 2013. During this period, the greatest increase in Lake Michigan level during a single month was 0.85 ft. The evaluation
concluded
that the time available
to respond to rising Lake Michigan prestorm levels would be approximately
eight weeks from the level at which PBNP procedures
require wave run-up barrier construction
initiation
(580. 7 feet IGLD 1955) until conditions
for the license basis maximum wave run-up could be reached. With respect to the identified
performance
deficiency, this eight week time period provides significant
opportunity
to identify and correct deficiencies
with flood barriers.
The updated analysis performed
in support of this evaluation
contains significant
margin, including
that the PRA analysis does not account for the significant
time available
for Operators
to take actions in response to rising lake levels. Attachment
4 provides the supporting
information
associated
with the rate of change in Lake Michigan water level and required Operator actions. Conclusion
The updated external flooding analysis shows that the frequency
of reaching a calculated
water level that impacts safety related equipment
is very low. The PRA analysis, using the calculated
water levels, determined
that affected equipment
results in a very low CDF. Therefore, the failure to establish
adequate procedure
requirements
to implement
external flooding wave run-up protection
features as described
in the FSAR has very low safety significance, based on the calculated
The Individual
Plant Examination
for External Events (IPEEE) contains estimates
and assumptions
that are overly conservative
and it is not appropriate
to use in the safety significance
determination
for this performance
deficiency.
The IPEEE estimated
that water levels would be substantially
higher with the same input assumptions, because of the many simplifications
that were used at the Page 7 of 8
time. With more accurate site information
and a more rigorous tool for analysis, the conservatisms
of the IPEEE were shown to be excessive.
Attachments
1) Calculated
Average External Water Levels at Turbine Building 2) Point Beach Revised External Flood Safety Significance
Determination
3) Continued
Service Water Pump Availability
with Loss of DC Control Power 4) Lake Michigan Level Rate of Rise Page 8 of 8
ATTACHMENT
1 NEXTERA ENERGY POINT BEACH, LLC POINT BEACH NUCLEAR PLANT CALCULATED
AVERAGE EXTERNAL WATER LEVELS AT TURBINE BUILDING 20 Pages Follow
CALC. NO. CALCULATION
COVER SHEET FPL-076-CALC-004 N E RC O N REV. 1 PAGE NO. 1 of 20 Title: Calculated
external average water levels at turbine building Client: NextEra Energy (NEE) Project: FPLPB025 Item Cover Sheet Items Yes No 1 Does this calculation
contain any assumptions
that require confirmation?
X (If YES, identify the assumptions)
2 Does this calculation
serve as an "Alternate
Calculation"? (If YES, identify the X design verified calculation.)
Design Verified Calculation
No. 3 Does this calculation
supersede
an existing calculation? (If YES, identify the X superseded
calculation.)
Superseded
Calculation
No. Scope of Revision:
Text revised on Page 15 Revision Impact on Results: No impact to results. Text only. Study Calculation
D Final Calculation Safety-Related Non-Safety Related D (Print Name and Sign) Originator:
Shaun W. Kline . o , Date: 0 7/1 Si z_n 1 3 Design Verifier:
Justin Pistininzi
(;16-
......._...
Date: o ? /1 1.-/ ":l '0/J Approver:
Paul Martlnchlch
/ '-:J.z (j AA ... Date: t7 7 J1 0 J U)3 /
CALC. NO. CALCULATION
FPL-076-CALC-004
REV. 1 REVISION STATUS SHEET PAGE NO. 2 of 20 CALCULATION
REVISION STATUS REVISION DATE DESCRIPTION
1 July 15, 2013 Initial Issue PAGE REVISION STATUS PAGE NO. REVISION PAGE NO. REVISION All pages 1
REVISION STATUS Attachment
NO. PAGE NO. REVISION NO. Attachment
NO. PAGE NO. REVISION NO. All Attachments
All Pages 1
CALC. NO * .. CALCULATION
FPL-076-CALC-004
I j I E N ERC ON DESIGN VERIFICATION
PLAN REV. 1 AND SUMMARY SHEET PAGE NO. 3 of20 Calculation
Design Verification
Plan: Apply CSP Number 3.01, Revision 6, Section 4.5.a, Design Review Method and to include at a minimum: 1. Review and verify the design inputs, references
and tables to ensure that the Calculations
Results, as they conform to the design methodology
and design guidance, are correct. (Print Name and Sign for Approval-mark "NIA" if not required)
Approver:
Paul Martinchich Date: 07/ >:s-)"A?J J 3 Calculation
Design Verification
SummarY':
After reviewing
this calculation
and all related documents
for Revision 0, I have come to the following
conclusions:
1. The methodology, design inputs and approach are appropriate
for the derivation
of all calculated
results. 2. The results of the Calculation
are reasonable
based on verified input values. 3. The report text and general flow of the document is clear and concise. Based on the above summary, the calculation
is determined
to be acceptable. (Print Name and Sign) Design Verifier:
Justin Pistininzi
S/eZJ_p/-_ Date: 0 7/tr::-/ 'J-o£3. Others: N/A ?/"' Date: I I
CALC. NO. FPL-076-CALC-004
I W EN E RCON CALCULATION
DESIGN VERIFICATION
REV. 1 CHECKLIST
PAGE NO. 4 of20 Item Cover Sheet Items Yes No N/A 1 Design Inputs -Were the design inputs correctly
selected, referenced (latest X revision), consistent
with the design basis and incorporated
in the calculation?
2 Assumptions-
Were the assumptions
reasonable
and adequately
described, X justified
andfor verified, and documented?
3 Quality Assurance-
Were the appropriate
QA classification
and requirements
X assigned to the calculation?
4 Codes, Standard and Regulatory
Requirements-
Were the applicable
codes , X standards
and regulatory
requirements, including
issue and addenda, properly identified
and their requirements
satisfied?
5 Construction
and Operating
Experience
-Has applicable
construction
and X operating
exper i ence been considered?
6 Interfaces-
Have the design interface
requirements
been satisfied, including
X interactions
with other calculations?
7 Methods -Was the calculation
methodology
appropriate
and properly applied X to satisfy the calculation
objective?
8 Design Outputs-Was the conclusion
of the calculation
clearly stated, did it X correspond
directly with the objectives
and are the results reasonable
compared to the inputs? 9 Radiation
Exposure-Has the calculation
properly considered
radiation
X exposure to the public and plant personnel?
10 Acceptance
Criteria -Are the acceptance
criteria incorporated
in the X calculation
sufficient
to allow verification
that the design requirements
have been satisfactorily
accomplished?
11 Computer Software -Is a computer program or software used, and if so, are X the requirements
of CSP 3.02 met? COMMENTS: (Print Name and Sign) Design Verifier:
Justin Plstlnlnzi Date: D7 It s/ J..o£3. Others: N/A ,?/ Date: I
E N ERCO N CALCULATION
CONTROL S H EE T T AB L E O F C ONT E NT S C ALC. NO. F PL-076-CALC-004
R E V. 1 PAG E NO. 5 of 20 1. PURPOSE AND SCOPE ............................................................
.........................................................
....... 6 2. SUMMARY OF RESULTS AND CONCLUSIONS
............................................................................
.........
6 3. REFERENCES
..........
.............
.................................................................................................................... 9 4. ASSUMPTIONS
..............................
................................................................................
.......................... 10 5. DESIGN INPUTS ..............................................
......................................
.............................
..................... 10 6. METHODOLOGY
........................................................................................................
...................
.......... 11 7. CALCULATIONS
............................
......................................
.................................................................... 14 List of Figures FIGURE 1-1: COASTAL INUNDATION
COMPONENTS
......................................................
........................
.... 6 FIGURE 2-1: OBSERVATION
POINTS AT POINT BEACH NUCLEAR PLANT (PBNP) .....................
............
8 FIGURE 6-1: EFFECTIVE
RUNUP SCHEMATIC
...............................
............
..............
.................................. 14 FIGURE 7-1: MAXIMUM WAVE BREAKING DISTANCE OF THE LARGEST WAVES NORMAL TO THE SOUTHWEST
CORNER OF THE PUMP HOUSEfTURBINE
BUILDING AT POINT BEACH NUCLEAR PLANT (PBNP) ........................................................................................................
........................... 18 FIGURE 7-2: SCHEMATIC
OF RESULTS FROM TABLE 7-3 FOR SWL=587.00 FT-IGLD55
USING TH9 MEAN WAVE SETUP .......................
......................
...........................
......................
....................
....... 19 List of Tables TABLE 5-1: INCIDENT WAVE RUN UP AND WATER ELEVATION
CALCULATION
INPUTS ........................ 10 TABLE 7-2: CALCULATION
RESULTS FOR THE MAXIMUM STRUCTURAL
LOADING ANALYSIS ...........
16 TABLE 7-3: CALCULATION
RESULTS FOR THE AVERAGE EXTERNAL WATER LEVEL PROXIES ON THE TURBINE BUILDING ...................................................................................................
................. 17
E N ERCO N CALCULATION
CONTROL SHEET 1. Purpose and Scope CALC. NO. FPL-076-CALC
-004 REV. 1 PAGE NO.6 of 20 This calculation
is performed
under NextEra Energy (NEE) contract order 02306247 to determine
a(n) * average water level proxy at the turbine building for the PRA leakage analysis, and * maximum water level proxy at the turbine building for a structural
loading analysis on the turbine building's
rollup doors and the jersey barriers due to effects of storm surge in Lake Michigan at the Point Beach Nuclear Plant (PBNP). The purpose of this calculation
is to provide a calculation
by empirical
relationship
of incident wave run up elevations
beyond the standing water elevation, which is comprised
of the still water level (SWL) and wave setup (FEMA, 2005; Dean and Dalrymple, 2007; USACE, 2011). The initial SWL is prescribed
and the wave setup is computed by the DELFT3D model (ENERCON , 2013a). Wave runup includes many simultaneous
processes , and is the sum of static wave setup, dynamic wave setup, and incident wave runup (swash), as shown in Figure 1-1. To adequately
address the water elevations
on critical infrastructure
at PBNP, an empirical
relationship
computation
of the latter parameter (incident
wave runup) is required.
Proxies for critical total water elevations (which include the combined effects of SWL, wave setup, and individual
wave swash) on the turbine building are also computed. Results and conclusions
from this calculation
can be used to determine
the effect of waves and flooding on the turbine building at PBNP. For instance, the calculated
average water levels can be used to compute water leakage into the building and the maximum water level can be used to determine
the highest forces against the turbine building rollup doors. In ci dent I ************** ****** Coastal Inundation
Components (adapted from USACE. 2012) I ********************************************...
.......... ':::.::::.:.:**************** .. . Wav e Setup ******************** \ \. .... ** ******** Stand i ng Water Eleva l i on .. 2 J _ / ** ............ ** Still Wa t er level SWL Wind S elul
level)
Pre-slormAnl e cedent ----Water level (of la k e Mich i gan) G) Determined
In CLB (FSAR & IPEEE) Calculated
by Numerical
Modeling (DELFT3D)
@ Hand-Calculated
by Empirical
Relationships (FEMA & USACE) Note: Drawing not lo s ca le Figure 1-1: Coastal Inundation
Components
2. Summary of Results and Conclusions Conservative parameters
were used whenever available
in this analysis. Where conservative
values were not available, reasonable
inputs in accordance
with industry standard practice and justification
were used. Therefore, the results of this analysis are bound i ng for PBNP.
ENERCON CALCULATION
CONTROL SHEET CALC. NO. FPL-076-CALC-004
REV. 1 PAGE NO.7 of 20 This analysis first considered
incident wave runup, which empirically
has been shown to be a function of deep-water
characteristics
and beachface
slope (Stockdon, 2006; FEMA, 2005; Dean and Dalrymple, 2007; USAGE, 2011 ), to help determine
a total water elevation
above the still water level and wave setup components
modeled in DELFT3D (ENERCON, 2013a). Beach/beachface
characteristics
and breaking wave locations
were found near the southwest
corner of the pump house adjacent to the turbine building (observation
point BP2, see Figure 2-1), where ponding occurs in the most severe cases (ENERCON, 2013a). We also provide a water elevation
proxy considering
the mean setup, rather than the peak surge level simulated
in DELFT3D (ENERCON, 2013a). The calculated
average setup method produces a maximum mean water level proxy of 0.31 feet on the turbine building (588.51 ft-IGLD) during the case IPEEE still water level elevation
of 587 ft-IGLD55 (PBNP, 1995; PBNP, 2013). This value can be used to determine
the effective
water leakage experienced
into the turbine building from pooling water against the doors. We find an incident wave run up greater than 1.65 feet will occur for less than 2% of the storm duration (ENERCON, 2013a). Accordingly , a wave bore exceeding
2.19 feet (590.39 ft-IGLD55)
could be expected less than 2% of the storm at the turbine building in the most severe IPEEE still water level case of 587 feet-International
Great Lakes Datum 1955 (henceforth
IGLD55) (PBNP, 1995; PBNP, 2013). For an initial water level of 586 ft-IGLD, maximum runup may reach the turbine building, but mean water level proxies indicate no persistent
water present. This calculation
can support analyses of door, building, and barrier stability
in the presence of increased water
level and/or wave attack. The results in this calculation
are applicable
for a small, yet critical range of the turbine building near the southwest
corner of the pump house. Conservative
methods were applied to account for uncertainties
related to the inputs. This incident runup calculation
and total water elevation
proxies can be applied to other PBNP locations, but the methodology
and assumptions
presented
should be considered
first. The total water elevations
are expected to be lower at other PBNP turbine building locations
of interest, since the maximum setup of the observations
in Figure 2-1 was selected for this analysis (ENERCON, 2013a).
ENERCON CALCULATION
CONTROL SHEET Shoreline
CALC. NO. FPL-076-CALC-004
REV. 1 PAGE NO.8 of 20 .fo4LN3 0 Observation
points that provided water levels (wave setup) used in the wave runup calculation. Approximate
Scale: 1" = 200' Figure 2-1: Observation
Points at Point Beach Nuclear Plant (PBNP).
E N ERC ON CALCULATION
CONTROL SHEET 3. References
CALC. NO. FPL-076-CALC-004
REV. PAGE NO. 9 of 20 3.1 Dean and Dalrymple, 2007, "Water Wave Mechanics
for Engineers
and Scientists," World Scientifc , 353 pp. 3.2 Deltares, 2012, Deltares Systems, "DELFT3D-WAVE
User Manual," updated 2012. 3.3 ENERCON, 2013a, ENERCON Services, Inc. (ENERCON), "DELFT3D Modeling of Surge and Wave Runup, Revision 0," Calculation
Number FPL076-CALC-003 , 2013. 3.4 ENERCON, 2013b, ENERCON Services, Inc. (ENERCON), "Mean Wave Flow, Revision 0," Calculation
Number FPL-076-CALC
-006, 2013. 3.5 FEMA, 2005, Federal Emergency
Management
Administration (FEMA), "Guidelines
and Specifications
for Flood Hazard Mapping Partners," D.4.5 Wave Setup, Runup, and Overtopping.
3.6 FEMA, 2007, Federal Emergency
Management
Administration (FEMA), "Guidelines
and Specifications
for Flood Hazard Mapping Partners," D.2.8 Wave Runup, and Overtopping.
3.7 FEMA, 2012, Federal Emergency
Management
Administration (FEMA)," FEMA Great Lakes Coastal Guidelines, Appendix D.3 Update," D.3 Coastal Flooding Analyses and Mapping: Great Lakes. 3.8 Mase , 1988, "Spectral
Characterisitcs
of Random Wave Runup," Coastal Engineering, Vol. 12, No.2, pp.175-189. 3.9 Melby, 2012, United States Army Corps of Engineers, Coastal and Hydraulic
Laboratory, "Wave Runup Prediction
for Flood Hazard Assessment (Draft)." 3.10 PBNP, 1995, Point Beach Nuclear Plant (PBNP), "Point Beach Nuclear Plant Individual
Plant Examination
of External Events (IPEEE) for Severe Accident Vulnerabilities
-Summary Report ," Wisconsin
Electric Power Company, June 30, 1995. 3.11 PBNP, 2013, Point Beach Nuclear Plant (PBNP) Design Information
Transmittal (OfT), Modification
Process, " Still Water Elevations (IGLD55) to be used for the FPL-076 series of calculations
in the PBNP wave analysis to match up with existing event probabilities," July 11, 2013. 3.12 S&L, 1967, Sargent and Lundy (S&L), "Maximum Deep Water Waves & Beach Run-up at Point Beach," 1967. 3.13 Stockdon, 2006, "Empirical
parameterizat
i on of setup, swash, and runup," Coastal Engineering, Vol. 53, No. 2 , pp. 573-588. 3.14 USAGE, 2011, United States Army Corps of Engineers (USACE), "Coastal Engineering
Manual," EM 1110-2-1100 , updated 2011. 3.15 USACE, 2012, United States Army Corps of Engineers (USACE), "Statistical
Analysis and Storm Sampling for Lakes Michigan and St. Clair," 2012.
E N E R C ON CALCULATION
CONTROL SHEET 4. Assumptions
CALC. NO. FPL-076-CALC-004 REV. 1 PAGE NO. 10 of 20 4.1 No reduction
factors due to differing
surface roughnesses
have been applied. The beach/beachface
extent includes predominately
sand, grass, gravel, and asphalt, which require no reduction (FEMA, 2005). Applying no reduction
factors is the most conservative
approach for wave runup calculations.
4.2 The conversion
from 2% incident wave runup elevation
to 50% incident wave runup elevation
is based on an empirical
relationship
applied to total run up for i rregular waves (Mase, 1988; USACE, 2011 ). It is assumed that the conversion
applies equivalently
for wave setup and incident runup and that the conversion
is valid for waves modeled in FPL-076-CALC-003.
Given the conservative
method of calculating
incident runup and the lack of accepted industry standards
for calculating
mean incident runup heights, this is a reasonable
approach.
4.3 An effective
runup elevation, or average elevation
of the wave runup bore over its entire wavelength (wave period), is determined
by assuming the runup bore maintains
a sinusoidal
shape above the mean water surface, which is a conservative
approach for a linear wave form. An effective (average)
height for this bore is used to provide a proxy for mean effective
incident runup elevations. Although breaking waves become nonlinear
and lose their sinusoidal
shape (Dean and Dalrymple, 2007), this approach provides an approximation
of the average (effective)
runup height. It is a reasonable
and conservative
approach given the lack of industry standard in the derivation
of such a parameter.
4.4 Wave setup is assumed to be a constant value near the turbine building.
The maximum or mean water level at observation
points (BP2, SS4, or SS5) near the turbine building are used to determine
the wave setup value (height above the initial still water level). This calculation
provides a value of water levels near the southwest
corner of the pump house and may differ at other PBNP locations. However, the calculated
level bounds the expected level at the turbine building.
5. Design Inputs The design inputs are listed in Table 5-1 below. A maximum wave period of 10 seconds was used to account for the maximum wind-generated
periods determined
in FPL-076-CALC-003 (Enercon, 2013a). Table 5-1: Incident Wave Run up and Water Elevation
Calculation
Inputs Value Units Source(s)
Ho 23.5 ft ENERCON, 2013a T 10 s ENERCON, 2013a Wave 120 degrees ENERCON, 2013a Direction
Wind 90 degrees ENERCON, 2013a Direction
PBNP, 2012 m 0.025 ft/ft S&L, 1976 ENERCON, 2013a 587.64 587 PBNP, 1995 SWL 586 ft-IGLD55
585 PBNP, 2013 583
CALCULATION
CONTROL SHEET 6. Methodology
6.1 Runup CALC. NO. FPL-076-CALC-004
REV. PAGE NO. 11 of 20 Run up (R) is the maximum elevation
of wave uprush above the still water level, consisting
of wave setup (11). the elevation
of the water surface due to wave action, and oscillatory
wave swash from breaking waves (USAGE, 2011 ): R = 1J + R/Nc (FEMA, 2005 , 0.4.5-1) where: R = total runup (ft) 11 = combined static and
dynamic wave setup (ft) R1Nc = incident wave run up due to oscillatory
wave swash (ft) Physically, R is the local maximum in water elevation (USAGE, 2011 ). No reliable theoretical
formulations
for run up exist currently
because the controlling
processes
are complex and nonlinear.
Rather, empirically
derived relationships
are used to estimate runup (USAGE, 2011). Many of these formulae relate total runup (R) to wave characteristics
and beachface
morphology (i.e. slope). For the purposes of this analysis, however, such a computation
would not be required. Computed OELFT30 water levels (in FPL-076-CALC-003)
include wave setup (11). Thus, the only additional
increase to the maximum water elevation
is the oscillatory
wave swash, RING. 6.2 Incident wave runup and maximum water levels for stability
analysis FEMA defines the 2% incident wave run up (RING 2%), the oscillatory
water elevations
attributable
to wave swash that is to exceed less than 2% of the time, as where: 111 R1Nc 2% = 0.6 f!!Q Ho -.ITO (FEMA, 2005, 0.4.5-11) R1Nc 2% = incident wave run up elevation
beyond water surface exceeded by <2% of waves (ft) m = beach slope (dimensionless)
Ho = deep-water
wave height (ft) Lo = deep-water
wavelength (ft) Thus, maximum incident runup occurs on steep beaches for large, long waves. Equation 0.4.5-11 was developed
empirically
along the Pacific coast (FEMA, 2005). It was chosen for this calculation
for two major reasons: 1) it provided a clear evaluation
of the incident wave run up, rather than the combined effects of incident runup and setup, and 2) it is conservative
approach, since frictional
dissipation
over a wide, sloped dissipative
beach, like Lake Michigan , would yield lower incident runup heights than the steeper, narrower surf zones of the Pacific coast (Stockdon, 2006). FEMA (2012) does provide unofficial (draft) guidelines
for the flood mapping on the Great Lakes, and promotes the use of Melby's (2012) compilation
of wave runup formulations
when applicable.
However, equations
therein reference
a total run up elevation (Melby, 2012, Figure 1 ). FEMA (2012) defines run up as a "statistic
associated with a group of waves or a particular
storm," indicating
that the equations
do not separate setup from individual
wave swash. Runup formulations
for structures
are also provided (FEMA, 2012), but are irrelevant
when the largest waves modeled in FPL-076-CALC-003
break far seaward of PBNP and do not
E N ERCO N CALCULATION
CONTROL SHEET CALC. NO. FPL-076-CALC-004
REV. PAGE NO. 12 of 20 directly impact any vertical infrastructure.
Hence, Equation 0.4.5.11 is the best known, applicable, yet conservative
estimate of only incident wave swash. The beach is defined as the area between wave breaking and the landward extent of wave runup (FEMA, 2005). The landward extent of the beach is defined as the turbine building near the southwest
corner of the pump house (observation
point BP2) where ponding was predicted
in the most severe cases (ENERCON, 2013a; Table 7-2). Additionally, the turbine building would interrupt
runup flow and is the structure
of top importance. The elevation
of the bottom of the turbine building door is 588.2 ft-IGLD55. At PBNP, the seaward extent of the beach was located where wave breaking occurred, as predicted
by the DELFT30-WAVE
model (ENERCON, 2013a). Larger waves began breaking -700 feet from the turbine building, whereas smaller wind-generated
waves, which produce significantly
less incident runup broke approximately
-250 feet from the BP2 observation
point (ENERCON, 2013a). In deep-water, wavelengths
are directly related to the wave period (T): (FEMA, 2005, 0.4.5-10)
where: T =wave period (s) Incident runup heights thus become a function of deep-water
wave height and period, as well as the beach slope. The largest incident wave run up values occur on steep beachfaces
for waves that are large {Ho) and long (T). Thus, the simulations
with the largest Ho and T values along the deep-water
boundaries
would produce the highest incident wave run up elevations.
The water elevation
given by SWL +I"JMAX+RINC
2% (Wl2%) is a proxy for the maximum water level reached during the storm. It is the value used in stability
analysis used of the turbine building's
rollup doors and jersey barriers.
6.3 Effective
incident runup to determine
external water levels on turbine building The incident wave runup (RINC) is only an instantaneous
water elevation (Figure 6-1). To better understand
the time-averaged, mean total water level, an average runup elevation
proxy may be developed. At PBNP, the mean water level is an important
factor in the leakage experienced
in the turbine building.
After a wave breaks, it continues
as a bore up the beachface
until gravity limits its upward swash rush or it is interrupted
by a hard structure. For sinusoidal
bores that are equally spaced (i.e. the length of the bore is equal to the space between bores, the mean elevation
can be given in two parts. The first part is the same calculation
performed
in FPL-076-CALC-006, and the result from that analysis (Equation
6-2 in FPL-076-CALC-006)
is provided here: where: A = n1Nc2%L BORE 2 1f AsoRE = area under the wave bore (ft 2) L = wavelength (ft) (6-1) The average height of that bore is given by dividing by half of the nearshore
wavelength, L/2 (see Figure 6-1 ): where: -h -_ A BORE _ RINC 2% BORE -Lj2 --lf-hBoRE = average height of the bore (ft) (6-2)
ENERCON CALCULATION
CONTROL SHEET CALC. NO. FPL-076-GALC-004
REV. 1 PAGE NO. 13 of 20 Note that the height of the wave bore is not a true wave height; rather, it is a wave amplitude, since the trough of the bore is neglected. The second part of the calculation
is the space between bores, which is assumed to be at the standing water elevation (Figure 6-1). Since the 'bore' has a height of zero in this range, the overall effective
height of the bore, and subsequently
of the incident run up (REFF 2%), if the next bore is assumed to follow the profile in Figure 6-1, is given by: R _ hBoRE _ R/Ncz% EFF2% (6-3) where: REFF 2% = effective
run up height (ft) This value (REFF 2%) is used as a proxy of the wave runup provided by the incident runup (RJNc) predicted
by Equation 0.4.5-11 from FEMA (FEMA, 2005). This approximation
is a conservative
approach of the linear wave profile since the wave trough is neglected.
Additionally, the USAGE (2011) provides empirical
formulas for various total run up thresholds (e.g. RMAx, R2%, R) for irregular
waves (USAGE, 2011 ). If incident wave run up and wave setup, the two components
of total wave runup, are assumed to vary equally (i.e. increase/decrease
by the same percentage)
between these various thresholds, then a comparison
of the empirical
formulas will allow for a conversion
of REFF 2%, derived from applying Equation 6-3 to an R1Nc 2% computation, to an equivalent
REFF 5o% proxy for R, the mean run up calculation (USAGE, 2011): where: R o.aaR EFF 50% = l.0 6 EFF 2% REFF 50% = effective
run up height proxy for R (ft) REFF 2% = effective
run up height proxy for R1Nc (ft) (6-4) The coefficients
in Equation 6-4 (0.88 and 1.86) are found in Section 11-4-4 of USAGE (2011 ). This value (Rm 5o%) can be used as a proxy for average runup elevation, although it should be noted that this elevation
is not static and the instantaneous
level oscillates
around this value, as shown in Figure 6-1. Physically, REFF so% is equivalent
to the average height that run up will reach 50% of the time. Similarly, REFF 2% is the average height that runup will reach 2% of the time. Thus, SWL +i]+REFF 50% (WL50% EFF) where iJ is the mean wave setup, can be thought of as a proxy for the mean water level. Instantaneous
water elevations
range between the standing water level and the maximum extent of run up. WLso% EFF is used to compute mean water leakage into the turbine building.
E N ERCO N Turbine building Note: drawing not to scale U2 CALC. NO. FPL-076-CALC-004
CALCULATION
CONTROL SHEET REV. L PAGE NO. 14 of 20 Instantaneous
water level Standing water elevation (SWL + fl*) Floor elevation
(588.2 ft-IGLD55)
- Note: wave setup (fl) was considered
either as a maximum modeled level (flMAX), which was used in calculations
for the structural
loading analysis, or a mean level (ij), which was used in the computations
for average external water level proxies at the turbine building. Figure 6-1: Effective
Run up Schematic
7. Calculations
These cases examine the incident wave run up for the largest (significant
wave height, Hs = Ho = 23.5 feet) and longest (T = 10 seconds) deep-water
waves with no barriers present and each evaluated
SWL, shown in Table 7-1 (ENERCON, 2013a). From Equation 0.4.5-10, the deep-water
wavelength (Lo) of these waves would be 512.32 feet. These parameters
provide a worst-case
flooding scenario for each initial SWL; all input values are shown in Table 5-1. For these deep-water
wave conditions, the maximum wave setup ('lMAX) was 1.74 feet, corresponding
to the still water level of 587 ft-IGLD55, as found in FPL-076-CALC-003 (ENERCON, 2013a). For the lower still water levels, the maximum wave setup narrowly ranged between 1.20 and 1.28 feet (ENERCON, 2013a). This result is likely attributable
to the relatively
steep sloping bathymetry
at the seaward edge of PBNP. For the highest still water level, 587.64 ft-IGLD55, the maximum setup at BP2 was 1.46 feet. Above a threshold
water level (between 586 and 587 ft-IGLD55), waves and accompanying
setup make it close to the turbine building;
below it, the wave setup height appears to be quite stable. Please refer to FPL-076-CALC-003
for a more comprehensive
discussion
and presentation
of the DELFT3D setup results. Mean wave setup (i]) ranged from 1.12 to 1.39 feet (ENERCON, 2013a). If observation
point BP2 was submerged , then it was used to determine
the maximum and average wave setup, as it was d i rectly adjacent to the turbine building (see Figure 2-1). If that point was dry for the entire simulation, then observation
point 884 or 885, the next closest inundated
points, were used. The mean wave setup was computed for only the durations
in which BP2 (or neighbor observation
point) experienced
flooding, which often lagged the start of the model by several minutes (ENERCON, 2013a).
ENERCON CALCULATION
CONTROL SHEET CALC. NO. FPL-076-CALC-004
REV. 1 PAGE N0.15 of 20 The largest waves, responsible
for the highest incident run up elevations, break furthest seaward of the turbine building (Figure 7-1). The slope of the beach/beachface
for this calculation
was divided into two segments, after the methodology
shown in Figure 0.2.8-1 of FEMA (2007). The landward segment extended from near the turbine building (observation
point BP2, see Figure 2-1) out to the edge of the topographic
map of PBN. The elevation
of the BP2 is 587.35 feet-IGLD55
and the elevation
at the seaward edge of the topographic
map is 573.35 feet-IGLD55.
The distance between these points is 350 feet, providing
an upper beach slope of 0.04. Seaward of this segment, the beach slope is 0.01 out to 1,000 feet from the turbine building (S&L, 1976). The DELFT3D model showed wave breaking initiating
-700 feet from the turbine building (Figure 7-1), so the horizontal
extent of this segment is 350 feet. A weighted average of the overall beach slope was computed to yield an average value of 0.025. This beach slope (m) was used in all of the wave runup calculations, since only minor shifts (-20 feet) occurred in wave breaking locations
due to different
initial still water levels. From the calculated
beachface
slopes and deep-water
wave conditions, the incident wave runup (RINc) was calculated
to be 1.65 feet. This oscillatory
swash operates on top of the wave setup (11), so this result must be added to the SWL (583, 585, 586, 587, OR 587.64 ft-IGLD55)
and modeled maximum or mean setup. Thus, the water elevation (SWL +11MAx+R1Nc
2%) which would be exceeded less than 2% of the storm is 590.39 IGLD55 in the 587 ft-IGLD55
SWL case, the most severe still water level in the IPEEE (PBNP, 1995; PBNP, 2013). For this incident wave runup, an instantaneous
water depth of up to 2.19 feet at 590.39 ft-IGLD55 (Table 7-2) when SWL = 587 ft-IGLD55
could be realized at the turbine building. This water depth may be used to calculate
loading against the turbine doors. Physically, this elevation
is a close proxy for the maximum water elevation
for the provided still water level, wind, and wave characteristics, but could be exceeded less than 2% of the storm. The effective
runup (Rm 2%), calculated
from Equation 6-3, is 0.26 feet. The effective
height that 50% of individual
wave run ups will exceed (REFF so%), calculated
from Equation 6-4, is 0.12 feet. Using inputs from Table 5-1 and the calculated
R1Nc, REFF2%, and REFFSo% from section 6.2 and 6.3, water level proxies were computed for turbine building's
east wall. Results are shown in Table 7-3, and the most severe IPEEE case is shown schematically
in Figure 7-2 (PBNP, 1995; PBNP, 2013). The incident runup remains the same in each case, but the overall water elevation
proxies differ (Table 7-3). When the BP2 observation
point was dry, the next closest submerged
observation
point (SS4 or SS5) was used to determine
the maximum or mean wave setup (see Figure 2-1 and ENERCON, 2013a). The mean water surface proxy (WLso% EFF) is above the elevation
of the turbine building floor during only the most elevated initial still water levels, 587 and 587.64 ft-IGLD55.
For the 586 ft-IGLD55
case, runup would be expected to impact the structure
less than 0.65 feet (588.85 ft-IGLD55)
for 98% of the storm. The effective
runup elevations
indicate no permanent
ponding due to wave setup and swash. In the other two initial water level cases, 583 and 585 ft-IGLD55, more than 98% of the incident wave runups would not reach the turbine building floor; similarly, the mean water surface elevation
proxy indicates no persistent
water on the building doors. A maximum mean setup (if) also was used to calculate
the total effective
water elevation
proxies used to determine
leakage into the turbine building. The mean water level proxy (WLsoo;, EFF) is above the turbine building floor elevation
by 0.31 feet in the most severe IPEEE case, SWL = 587.00 ft-IGLD55 (PBNP, 1995; PBNP, 2013). No standing water is predicted
for the SWL = 586 ft-IGLD55
case, with WLso% EFF = 587.24 IGLD55. Further, no standing water and less than 2% of incident wave runup is expected for the initial SWL = 583 or 585 ft-IGLD55
cases.
--**--------CALC. NO. FPL -076-CALC-004
E N ERCO N CALCULATION
CONTROL SHEET REV. 1 PAGE N0.16 of 20 Table 7-2: Calculation
Results for the Maximum Structural
Loading Analysis.
Inputs for Maximum Incident Runup (Rmc2%) and Setup (I"JMAX) for each SWL Case. Output is a Dynamic Total Water Level (WL2%). Ho T (s) m RiNC2% SWL Frequency
of I'] MAX SWL + I']MAX Wl:z% (ft) (ft/ft) (ft) (ft-IGLD55)
SWL (yr 1)* (ft) ** (ft-IGLD55) (ft-IGLD55)
23.50 10.00 0.025 1.65 587.64 9.9E-07 1.46 589.10 590.75 23.50 10.00 0.025 1.65 587.00 4.2E-06 1.74 588.74 590.39 23.50 10.00 0.025 1.65 586.00 5.4E-05 1.20 587.20 588.85 23.50 10.00 0.025 1.65 585.00 3.2E-04 1.21 586.21 587.86 23.50 10.00 0.025 1.65 583.00 1.4E-02 1.28 584.28 585.93 * SWL frequencies
are provided by PBNP (2013), formulated
from data i n PBNP (1995). ** maximum setup values (r]MAX), measured at either observation
point BP2 or SS5 (if BP2 was dry), obtained from DELFT3D simulations (FPL-076-CALC-003)
corresponding
to still water levels (SWL) and deep-water
wave conditions
of Ho = 23.5 feet and direction=
120 °. Note: This table represents
a temporary
condition
that would induce maximum wave runup for use in calculating
structural
loading on the turbine building.
*-------------------------------------------------------------
CALC. NO.
FPL -076-CALC-004
E i!" J E N ERCON CALCULATION
CONTROL SHEET REV. 1 PAGE N0.17 of20 Table 7-3: Calculation
Results for the Average External Water Level Proxies (WLso.,. EFF) on the Turbine Building.
Inputs for Highest Effective
In cident Run up (REFF so%) and Mean Setup (7]) for each SWL Case. Ho T (s) m REFFSO% SWL Frequency
of i] (ft) -SWL+i] Wlso%EFF (ft) (ftlft) (ft) (ft-IGLD55)
SWL (yr 1) '* (ft-IGLD55) (ft-IGLD55)
23.50 10.00 0.025 0.12 587.64 9.9E-07 1.13 588.77 588.89 23.50 10.00 0.025 0.12 587.00 4.2E-06 1.39 588.39 588.51 23.50 10.00 0.025 0.12 586.00 5.4E-05 1.1 2 587.12 587.24 23.50 10.00 0.025 0.12 585.00 3.2E-04 0.72 585.72 585.84 23.50 10.00 0.025 0.12 583.00 1.4E-02 0.84 583.84 583.96 * SWL frequencies
are provided by PBNP (2013), formulated
from data in PBNP (1995) . .. mean setup values (ij') averaged over the entire simulation
when flooding occurred, measured at either observation
point BP2 or SS4 (if BP2 was dry), obtained from DELFT3D simulations (FPL-076-CALC-003)
corresponding
to still water levels (SWL) and deep-water
wave condit i ons of Ho = 23.5 feet and direction
= 120 °. Note: This table represents
average water level proxies at the turbine building.
. -* ---------.... -.. -... 1:1 E N ERCO N *ru .. -,..-;:;-*
-" ..... 44.2835 44.283 44.2825 t §: 44.282 "' .5 .., 0 44.2815 0 <.> >-44.281 44.2805 44.28 44.2795 -87.538 CALCULATION
CONTROL SHEET -87.537 -87.536 -87.535 CALC. NO. FPL-076-CALC-004
REV. 1 PAGE NO. 18 of 20 --87.534 -87.533 -87.532 x coordinate (m) Figure 7-1: Maximum Wave Breaking Distance of the Largest Waves Normal to the Southwest
Comer of the Pump House/Turbine
Building at Point Beach Nuclear Plant (PBNP). Percent Breaking (Oo/o=No Breaking, 1=100% Breaking)
i s Shown in the Color Map Above.
Turbine building Note: drawing not to scale CALCULATION
CONTROL SHEET CALC. NO. FPL-076-CALC-004
REV. 1 PAGE NO. 19 of 20 SWL = 587 ft-IGLD55
Mean setup ________________
Wlsocro...£fu588.51
tt-IGLD55)"" i REFFSO%
Standing water elevation, SWL + i'j (588.39 ft-IGLD55)
Door/floor
elevation
(588.2 ft-IGLD55)
Results for deep-water
wave height= 23.5 ft. deep-water
wave direction=
120 °, SWL = 587 ft-IGLD55, and no barriers present. Legend R 1 Nc = max. incident wave run up ReFF = effective
wave run up ('time-averaged'
R 1 Nc) SWL = still water level (587 ft-IGLD55)
fj =mean wave setup at BP2 (ft) Wlso% EFF = 'average'
water elevation
proxy including
ReFF soo/o Figure 7-2: Schematic
of Results from Table 7-3 for SWL=587 .00 ft-IGLD55
using the Mean Wave Setup. The WLr;. EFF and EFFWL 2% are the Effective
Water Level Proxies Used to Determine
Water Leakage into the Turbine Building.
E N E R C ON CALCULATION
CONTROL SHEET CALC. NO. FPL-076-CALC-004
REV.1 PAGE NO. 20 of 20 Attachment
A (On DVD) Pages/ Worksheets/
File Name (References)
Revision File Dean and Dalrymple, 2007 NA File Delatres, 2012.pdf NA File ENERCON, 2013a 0 File ENERCON, 2013b 0 File FEMA, 2005 NA File FEMA, 2007 NA File FEMA, 2012 NA File Mase, 1988 NA File Melby, 2012 NA File PBNP, 1995 NA File PBNP, 2013 NA File S&L, 1967 NA File Stockdon, 2006 NA File USACE, 2011.pdf NA File USACE, 2012.pdf NA File
ATTACHMENT
2 NEXTERA ENERGY POINT BEACH, LLC POINT BEACH NUCLEAR PLANT POINT BEACH REVISED EXTERNAL FLOOD SAFETY SIGNIFICANCE
DETERMINATION
Performance
Deficiency
The licensee failed to establish
appropriate
procedural
requirements
to implement
external flooding wave run-up protection
design features as described
in the FSAR. Executive
Conclusion
The safety significance
of this issue is assessed to be of very low with margin for Units 1 and 2. Table 4 provides the core damage frequency (CDF) with and without barriers as well as the change in core damage frequency
with and without the barriers.
The basis of this conclusion
is that a detailed wave run-up analysis results in a calculated
water level much lower than the water levels previously
evaluated
in the IPEEE. The PRA analysis based on the updated engineering
analysis confirms that the IPEEE water levels were dominated
by estimates
and assumptions
that resulted in excessive
conservatism
for the 4.2E-06/yr
frequency
event. These lower water levels from the updated engineering
analysis result in fewer equipment
impacts. Background
The IPEEE response to GL 88-20, "Individual
Plant Examination
for Severe Accident Vulnerabilities," evaluated
external flood hazards for PBNP. This evaluation
was based in part on the analysis for external flood events conducted
in conjunction
with the NRC's TAP A-45 study. In order to evaluate the safety significance
of this issue, the data provided in the IPEEE was used to evaluate the change in CDF and large early release frequency (LERF). For the purpose of this evaluation
the "change" being considered
is the plant with and without the barrier protection
to 589.2 (IGLD-1955), as described
in the IPEEE report. To perform this evaluation, some simplifying
conservative
assumptions, providing
margin, are made: 1) Above 589.2 ft. IGLD 1955 (+9ft.), the impact of the flood is the same with and without barriers.
2) For the purposes of the PRA calculations, the water level inside the buildings
was assumed to equal the water level outside the Turbine Building at time zero. 3) Below 588.2 ft. IGLD 1955 (+8ft.), there is no impact from the flood (with or without barriers). 4) The PRA evaluation
assumes a concurrent
dual unit loss of offsite power (LOOP) due to the storm which is conservative
because the postulated
storm does not reach sustained
wind speeds that are expected to cause damage to offsite power distribution.
Page 1 of 8
Risk Assessment
PBP PRA Model Rev. 5.02 was used for this assessment.
Since this evaluation
will be applying the frequency
of the external flood outside of the PRA model, all initiators
in the internal events model were set to 0.0 with the exception
of the weather-centered
LOOP initiator (INIT-T1W).
By doing this, the value being quantified
is the conditional
core damage probability (CCDP), i.e., the core damage probability
assuming the initiator (external
flood in this case) occurs The following
steps were taken to evaluate the significance
of this issue: 1) Run CAFTA cases (average Testing & Maintenance)
for Units 1 and 2 with an E-10 truncation
limit with flags set to account for the postulated
equipment
failures. The results of the cases representing
the CCDPs for the five bins comprising
varying depths of water on the Turbine Building floor are shown in Table 1. For simplicity, only the maximum CCDP for each bin will be carried through the rest of this calculation.
2) In order to calculate .LlCDF for the water height ranges in this report , flood event frequencies
had to be derived. That was done by defining a relationship
between calculated
water levels and still water levels from Attachment
1. This relationship
is shown in Table 2. 3) The results of the curve-fit of the flood exceedance
frequencies
from Table 5.2.5-2 of the IPEEE are presented
in Table 3. Note that due to the data, two curve fits are presented.
The first curve fit represents
still water elevations
s585.1 ft IGLD 1955 and the second curve fit represents
still water elevations
> 585.1 ft IGLD 1955. 4) By using these developed
relationships, a frequency
is derived for a given calculated
flood level by determining
the associated
still water level from Table 2 and then using it to determine
the frequency
from Table 3. 5) The CDF is calculated
by multiplying
the Incremental
Flood Frequency (determined
from the relationships
in Tables 2 and 3, by the CCDP and is presented
in Table 4. 6) The .LlCDF was calculated
by subtracting
the CDF with barriers from the CDF without barriers for each bin. The Total .LlCDF was obtained by subtracting
the CDF Total with barriers from the CDF Total without barriers.
This information
is also presented
in Table 4. Note that based upon previous evaluations
and the very small CDF values, values for LERF were not calculated.
Due to the nature of the initiating
event, i t is judged that there is no unique challenge
to L E RF. Thus , the .LlLERF for this evaluation
is judged to be well below 1 E-09 /yr. The final calculation
of .LlCDF for this issue is determined
to be ?.E-09 /yr, which is of very low safety significance , with margin. Page 2 of 8
Margin The flood consequence
is considered
to be bounding and conservative
for the following
reasons: 1) All equipment
affected by the flood is assumed to be failed at time zero. Based on engineering
evaluations, the water accumulation
inside various areas of the plant would take over three hours prior to affecting
any safety significant
equipment.
2) No credit for
flood mitigation
actions taken in response to rising water levels throughout
the plant has been modeled. Due to the relatively
slow progression
of the postulated
flood, there should be time for the operators
or plant staff to respond to the rising water level and to protect and/or realign equipment.
3) No credit for
recovery actions taken in response to equipment
issues in the plant has been modeled. It is expected that some equipment
may be able to be recovered
and that other means to provide decay heat removal could be used, e.g., pumper trucks, B.5.b equipment, and portable generators.
4) The concrete barriers installed
at a lake level of 580.7 ft. (IGLD 1955), in accordance
with PC 80 Part 7, "Lake Water Level Determination," are assumed to be ineffective
in limiting the quantity of water. Page 3 of 8
Ta bl e 1 Maximum Conditional
Co r e Damage P robability
vs. Water Level Range Bins Range of Water Level CCDP (max) Bin on Turbine Equipment
Assumed Failed (1,7) Building Floor (4) (inches) (2,3) Offsite power assumed lost, Offsite Power Transformers
(1 X-01/03, 1 0 to <4.0 2X-01/03), 4.25 E-05 RHR Pumps (1/2P-1 OAIB), RHR Pump Suction from Containment
Sump B (1/2SI-851AIB) Charging Pumps (1 CV-2AIB/C and 2CV-2 4.0 to <8.0 2AIB/C), 6.87 E-04 Station Battery Chargers (D-07/D-08/D-09)
A Train Emergency
Diesel Generators (G-01, G-02), G-01/G-02 EDG Alarm & Electrical
Panels (C-34/C-35), G-01/G-02
EDG DC Power Transfer Control Panels (C-78/C-79), 3 8.0 to <12.5 4.16 KV Switchgear ( 1/2A-03/04
), 7.70 E-03 (5) 4.16 KV Vital Switchgear
A Train (1/2A-05), 1/2HX-11A, B RHR HX Shell Side Inlet Valves (1/2CC-738AIB), Non-Safety
Related 480V MCCs (B-33, 8-43), Steam Generator
Pump Seal Water Injection
Pumps (1/2P-99AIB)
480 V Vital MCCs A Train (1/2B-32), 4 Safeguards
Batteries (D-01, D-02), (6) 12.5 to <17 Service Air Compresso r (K-3B,) 8.92 E-02 Diesel Driven Fire Pump (P-35B), Instrument
Air Compressors (K-2AIB) Condensate
Pumps (1/2P-25AIB), Feedwater
Pumps (1/2P-28AIB), Service Water Pumps (P-32AIB/C/D/E/F), DC Distribution
Panels (D-63, D-64 ), Stand-by Steam Gene r ator Pumps 5 (P-38AIB), 1.00 Turbine Driven Auxiliary
Pumps (1/2P-29), Motor Driven Auxiliary
Pumps (1/2P-53), Service Air Compressor (K-3A), Safety Injection
Pumps (1/2-P12AIB)
Page 4 of 8
Notes: (1) "Equipment
Assumed Failed" for each range of water levels greater than 588.2 ft. IGLD 1955 is based on the elevation
of the limiting vulnerable
subcomponent.
(2) "Range of Water Level" is based on inches of water on the turbine building floor. (3) "Range of Water Level" 0 inches equals 588.2 ft. IGLD 1955. (4) The maximum CCDP from either unit is used in the downstream
calculations.
(5) It has been identified
that P-35A, Electric Fire Pump, may fail at an elevation
in Bin 3. Since this bin already fails 1A-05 (which powers 1 B-03, which powers the electric fire pump), there is no additional
consequence
of this component
failure. (6) It has been identified
that a control panel associated
with the 2P-29, Turbine Driven Aux Feedwater
Pump low suction pressure trip, may fail at an elevation
in Bin 4. A sensitivity
case was run that showed that the CCDP value would increase slightly to 9.0E-2. This small difference
compared to the CCDP value used for Bin 4 is not significant
in the conclusions
of this evaluation.
(7) Equipment
failures at the water level elevations
have been validated
against the most recent walk-downs
as documented
in EC 279398. Page 5 of 8
-l.() l.() m ..--I 0 _J <.9 :S (ii > Q) _J '-Q) ..... ro s "0 Q) -m ::J .2 ro l) Table 2 Calculated
Water Level Based on Still Water Lake Elevation
Still Water Elevation
to Calculated
Water Level Relationship
St ill Water Lake Calculated
Water Ele v ation Leve l (ft.IGLD-(ft. IGLD-1955) * 1955) 587.64 588.89 587.00 588.51 586.00 587.24 585.00 585.84 583.00 583.96 Relationship
Between Still Water Lake Elevation
and Calculated
Water Level (Level Against Turbine Hall) 590 589 588
587 586 585 584 583 582 583 584 585 586 587 Still Water Elevation (ft IGLD-1955)
588 NOTE: *Calculated
Water Level is taken from Table 7-3 of Enercon Calculation
FPL-076-CALC-004
Page 6 of 8
Annual Frequency (per yr) 3.69E-02 2.53E-04 3.45E-07 8.25E-11 Table 3 Annual Frequency
Based on Still Water Elevation
[Derived from Information
in IPEEE] Flood Frequency
-Curve Fit Equat ions Frequency-
Curve Fit (per yr) Still Water Elevation
IPEEE (ft IGLD 1955) from IPEEE StiiiWaterFREQ1
StiiiWaterFREQ2
IPEEE Table 5.2.5-2 582.5 3.7E-02 585.1 2.7E-04 4.8E-04 588.0 4.1 E-07 591.0 2.9E-10 Note where two values are provided, IPEEE StillWater
FREQ2 was used. (.J 1: (!) ::J C" E LL Ill ::J 1: 1: Point Beach Flood Hazard Frequency (from IPEEE Table 5.2.5-2) 1.E-01 ,-----------------------
---, <( 1.E-06
1.E-07
1.E-10 +-----,--------.-----,--------.----.---L----J
580.0 582.0 584.0
586.0 588.0 590.0 592.0 Still Water Flood Elevation (ft IGDL-1955)
Page 7 of 8
Tab le 4 .t.CDF Calcu l a t ion With and Without Barriers {1 'lH' t-t*n r:l:Iffl'm
Effective
Flood Incremental
Still Water Water
Bin Frequency
Flood Lake Level CCDP CDF CCDP CDF ACDF1 Frequency
Elevation (Range) (1) peryr peryr
ft (IGLD-peryr peryr peryr 1955) inches 1 5.6E-06 2.9E-06 586.93 0 to <4.0 4.25E-05 1.23E-1 0 O.OOE+OO O.OOE+OO 1.23E-10 2 2.7E-06 1.4E-06 587.23 4.0 to <8.0 6.87E-04 9.54E-10 O.OOE+OO O.OOE+OO 9.54E-10 587.53 8.0 to 3 1.3E-06 7.3E-07 <12.5 7.70E-03 5.60E-09 O.OOE+OO O.OOE+OO 5.60E-09 4 5.7E-07 3.2E-07 587.87 12.5 t o<17 8.92E-02 2.8 4 E-08 8.92E-02 2.84E-08 O.OOE+OO 5 2.5E-07 2.5E-07 588.21 >17 1.00E+OO 2.48E-07 1.00E+OO 2.48E-07 O.OOE+OO CDF CDF Total 2.83E-07 Total 2.76E-07 7.E-0 9 (1) E ff ect i ve wate r level is t he level o f water in the t urbine build i ng. Page 8 o f 8
ATTACHMENT
3 NEXTERA ENERGY POINT BEACH, LLC POINT BEACH NUCLEAR PLANT CONTINUED
SERVICE WATER PUMP AVAILABILITY
WITH LOSS OF DC CONTROL POWER As discussed
in Reference
2, a significant
contributor
to the difference
between initial NextEra and NRC staff estimated
changes in Core Damage Frequency (CDF) with failure of equipment
up to 589.2 feet of water IGLD 1955 is the PRA modeling of Service Water (SW) pump availability
upon loss of DC control power. NRC's SPAR model contains a presumption
that the SW pump becomes unavailable
upon loss of DC power. (It is important
to note that NextEra's
updated analysis does not result in water levels which would impact DC power.) With a Loss of Offsite Power (LOOP), all four installed
Emergency
Diesel Generators (EDGs) will start and energize their associated
buses. All six Service Water (SW) pump supply breakers will then sequence onto their respective
AC load centers. With respect NRC's SPAR model assumption
that SW would be unavailable
upon loss of DC power, an interruption
in DC control power does not cause re-positioning
of breakers.
DC control power provides remote breaker operation
of the 480 volt SW supply breakers by momentarily
energizing
either the opening or closing solenoid coils. The overcurrent
protective
device is not dependent
on DC control power and remains functional
without DC control power. Once a breaker is closed, a loss of DC control power will not cause it to open, and the connected
load will continue to be energized.
Therefore, the operating
SW pumps will remain in operation
if DC control power is lost. DC control power supplies the starting circuit of the EDGs, the power to initially
flash the field on an EDG that is starting, and provides the ability to remotely adjust the electric governor setpoint, and to adjust the voltage regulator
setpoint.
If an operating
EDG suffers a complete loss of DC control power, the electronic
governor will fail to full fuel demand, and the backup mechanical
governor will take over speed regulation.
The exciter and voltage regulator
are self-energized
from the generator
output, and will fail to the as-set voltage. The ability to locally adjust frequency
on the running generator
will remain available.
The pending loss of DC control power due to flooding would be anticipated, and would be acted upon by the Operator before the actual loss occurred.
Each battery charger would initiate a trouble alarm when it failed, providing
a minimum of 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> notice of the loss of the supplied bus. The one hour time is based on the minimum capacity of the batteries, and provides time to align the DC control power supplied to running EDGs, 4 kV switchgear, and 480 V Load Centers prior to the complete loss of control power. Abnormal Operating
Procedure
AOP-0.0 directs the Operator to realign control power from the normal source to the alternate
DC control power source. This includes realigning
the DC control power for Emergency
Diesel Generators
and 4 kV switchgear, and the direction
would be exercised
in anticipation
of the loss of the busses when the inability
to recover the overheated
chargers became evident. Page 1 of 2
If a running "B" train EDG were lost for any reason, the remaining "B" train EDG would be aligned to re-energize
the bus previously
supplied by the lost EDG using either ECA-0.0 (loss of AC power) or OI-35A (standby emergency
power alignment).
This would ensure the availability
of power to all 3 "B" train SW pumps. In the event that a SW pump needs to be started on an energized
bus , but does not have DC control power available
to effect remote operation, the procedural
direction
to "start pumps as necessary" will cause the Operator to start the pump by closing the breaker locally. The low service water pressure alarm response procedure
would direct this action, as would di r ection in the various abnormal operating
and emergency
operating
procedures.
Based on these considerat
i ons, it is concluded
that the postulated
combination
of a LOOP, loss of the "A" train buses, and loss of the D-07 , D-08, D-09 battery chargers does not limit the plant to only a single SW pump during long term operation. The actions for switching
to alternate
DC Control power are as follows: * The operators
will respond to control room alarms based on degrading
DC voltage * AOP 0.0 Vital DC System Malfunction, entry conditions
would be satisfied
and direct switching
to alternate
DC Control power for G-04 EDG. * If G-04 E DG would lose DC control power, guidance for local speed control is provided in E CA 0.0, Loss of all AC, for hydraulic
governor operation. * AOP 1 OA, Safe Shutdown local control procedure, provides guidance for local operation
of the Service Water pump breakers, if local operation, is required.
- A Nuclear Oversight
Observer completed
a satisfactory
observation
of the above actions in the field by 3 Auxiliary
Operators.
- The above field actions were timed and validated
to be completed
in aggregate
of <1 hour. * These Operator actions are part of the IN PO accredited
training programs for both initial and continuing
training for the Auxiliary
Operators. Local operation
of these breakers is trained on, tested, and evaluated
by our Operator Initial and Continuing
Training programs.
Conclusion
If a Service Water Pump is operating
when DC Control Power is lost it will continue operating
and if it is not operating
when DC Control Power is lost, the Operators
are trained and are procedurally
directed to start the pumps locally. If DC Control Power is lost to G-04 EDG , the operators
are trained and have procedural
guidance to locally control G-04 EDG's speed with the hydraulic
governor.
Page 2 of 2
ATTACHMENT
4 NEXTERA ENERGY POINT BEACH, LLC POINT BEACH NUCLEAR PLANT PBNP TIME TO RESPOND TO RATES OF RISE IN LAKE MICHIGAN WATER LEVEL Purpose The purpose of this evaluation
is to establish
the time available
to respond to rising levels in Lake Michigan before the design basis flood threat may be reached. This evaluation
does not rigorously
reevaluate
the point at which there is a threat from rising water. Design and Licensing
Basis No flood height elevation
has been calculated
for anything but the vertical wall on the east side of the forebay to date. This value is stated in the FSAR (Section 2.5) as 8.42 feet plant elevation.
It is based on a maximum undisturbed
lake level of +1.7 ft. plant elevation
plus a wave run-up of 6.55 feet against a vertical surface, and a sustained
level change of +0.17 feet of water based on conservative
value of sustained
easterly wind velocity of 40 mph over a fetch length of 70 miles and average depth of 465 feet of water. Thus, the maximum expected run-up on a vertical structure
would be 6.72 feet above the normal water level (resulting
in a plant elevation
of 8.42 feet) and somewhat less on a riprap slope. Plant Reaction to Lake Level Changes Prior to Revision 4 (issued March 14, 2013) Point Beach procedure
PC 80 Part 7 required installation
of pre-cast concrete barriers within 3 weeks when the level of Lake Michigan reached a reported level of 580. 7ft. IGLD 1955. The detailed directions
in the procedure
on how to obtain this information
would have resulted in using the currently
accepted International
Great Lakes Datum ("IGLD") of 1985. This elevation
equates to -0.2 feet plant elevation.
This procedure
is performed
monthly and ensures advance preparation
in anticipation
of a potential
high water event. Historical
Lake Level Changes To determine
how much advance notice it would have ensured, the historical
lake data archived by the National Oceanographic
and Atmospheric
Administration (NOAA) was reviewed.
The data for monthly average lake level contained
data from January 1918 through March 2013 was converted
to feet, and the difference
between successive
months calculated
to obtain the monthly rate of level change. As shown in the histogram
below, the distribution
of level change is asymmetrical.
Page 1 of 4
Histogram
of Rate of Level Change 140 9 0.00% 120 . 80.00% 100 70.00% 6 0.00% > 80 v c Gl :I .... 5 0.00% 60 ... 40.00% 40 3 0.00% 20.00% 20 0
Rate of Lake Level Change (ft/month)
Because the lake level as a function of time cannot be replicated
by any meaningful
function, it is instructive
to calculate
the maximum historical
one month and two month level changes. On one occasion, the rate of rise in the lake reached 0.85 ft in a single month (April, 1960). The next highest rate of rise ever observed was 0.69 ft/month during two successive
months (April and May 1929). As the length of the period increases, the monthly average rate of rise decreases.
The maximum monthly rate of rise for a three month period is 0.55 ft!month, and for a four month period it has been 0.48 ft!month.
A full listing of the data is appended to this evaluation.
IPEEE Trigger Points From Table 3-3 in the TAP A-45 report (recreated
in the IPEEE submittal), the combination
of lake level and wave run-up which gets to the 8ft plant elevation
(588.2ft IGLD 1955) occurs with a still lake level of about 582ft IGLD 1955. Since 580.2 IGLD 1955 corresponds
to 0.0 feet plant elevation, the still lake level at which the wave run-up reaches 8.0 feet , is 1.8 feet plant elevation.
Using this as the lake level at which the threat from rising water materializes , there is 2 feet between the "install barriers" trigger point contained
in PC 80 Part 7 and the threat level. Using the maximum historical
rise rates for one, two, three, and four months to consume the entire 2 foot margin (height differential)
would require a period (denoted as " available
time period") of: ( 2ft ) weeks T = * 4.33-----,--
Rate (n Months) month Page 2 of 4
Using this formulation, the following
results are obtained:
Rate of Rate Period Available
Rise Time Period Height From Differential (ft) ft!month months weeks Trigger Point (Weeks) 2 0.48 4 17.3 18.1 2 0.55 3 13.0 15.8 2 0.69 2 8.7 12.6 2 0.85 1 4.3 10.2 In all cases, the available
time period for the 2 foot rise exceeds the highest historical
value for that same time period. Therefore, the rate of rise and the available
time for each case is conservative. This indicates
that even in the "worst case" where lake level were rising at the most rapid historic 1 month rate of 0.85 ft!month, and sustained
it for an unprecedented
10 weeks, it would still take a little more than those 10 weeks to consume the 2 feet of margin from the time that the trigger point is reached until the threat level was reached. However, the surveillance
is only performed
monthly. So it is possible that the reported lake level could be just below (e.g., 0.1 foot less than) the "trigger point" level of 580.7 ft at the time that the procedure
is performed.
It would then take another month (4.3 weeks) to discover that the trigger point level had been exceeded.
Under this postulation, it is appropriate
to use the rise rate for n+1 months to determine
time to achieve the total rise. T = [( 2 ft ) -1 month] * 4.33 _w_e_e_k.,...s
Rate (n + 1 Months) month Using this formulation, the following
results are obtained:
Rate of Rate Period Available
Rise Time Period Height From Differential (ft) ft!month months weeks Detection
to Threat Level (Weeks) 2 0.48 4 17.3 -2 0.55 3 13.0 13.7 2 0.69 2 8.7 11.4 2 0.85 1 4.3 8.2 Using the conservative
approach described
above, it would still leave at least 8.2 weeks, after discovery
that the trigger point
had been exceeded, to complete preparations
for high water, even if the first opportunity
had been missed. The procedure
allows three weeks for installation
so that there would be 5.2 weeks available
to address barrier deficiencies
before lake level reaches the design basis flood level. At the time that the barriers would have been set, the deficiencies
in setting, placement, gaps, etc. would have been self-evident, just as they were when the station performed
a trial placement
in 2012. Page 3 of 4
Station Actions related to increasing
lake levels: * Weather Conditions
are monitored
daily by the Shift Technical
Advisor and inputted into Safety Monitor * Weekend look ahead by Work Week manager for weather effects on weather impact for weekend on Safety Monitor * Procedurally
directed Monthly Recording
of Lake Level per PC 80 Part 7 "Lake Level Determination" * Per PC 80 Part 7 at a Lake Level (580.7 ft.') the Jersey Barriers are installed
- At a lake level of greater than or equal to 588.2 ft the plant will declare an Unusual Event (HU 1.7) * At a lake level of greater than or equal to 589.2 ft the plant will declare an Alert (HA 1.6) As described
previously, it has been calculated
that, with the maximum historical
lake rise, it would take greater than 8 weeks to reach the CLB lake level of 581.9 ft. from a starting level of 580.7 ft. The jersey barriers , including
approximately
1000 sand bags, was installed
and inspected
in less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Conclusion
The time available
to respond to rising Lake Michigan pre-storm levels would be at least 8.2 weeks from the time of discovery
until the license basis flood level could be attained.
During 2012 , when the barriers were installed, it took less than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. Additionally , installation
of the modified barrier (which includes approximately
1000 sand bags) was completed
in less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Therefore, there is ample time to install the barriers and take appropriate
additional
actions. Page 4 of 4