ML20211M484
| ML20211M484 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 08/31/1999 |
| From: | Maine Yankee |
| To: | |
| References | |
| NUDOCS 9909090126 | |
| Download: ML20211M484 (4) | |
Text
p. .o r
1 Proc. No. 0-061 Rev. No. 5 28 THRU 38 - NRC HEADQUARTERS Page 4 of 5 DOCUMENT CONTROL DESK H. MILLER (11)
(' COPY NUMBER:
ATTACHMENT A MAINE YANKEE CONTROLLED DOCUMENT TRANSMITTAL FORM l DOCUMENT: DEFUELED SAFETY ANALYSIS REPORT l
L TRANSMITTAL ISSUE DATE: 8-31-99 TRANSMITTAL RETURN DATE*: 9-29-99 An error was found in Section 2.0 of the updates you recently received.
Due to the changes on page 247 a paragraph moved onto the next page, which i affected pages 2-48,249 and 2-50.
Please remove the following peges 248,2-49 and 2-50 all Rev.14, which will not change, because none of the text changed, and replace with the attached pages 2-48, 249 and 2-50.
l 1
The above listed oocument has been inserted into the assigned manual #ile and all superseded pages have been destroyed.
MANUAUFILE UPDATED BY:
[ Please Print Name DATE:
Signatum ,
CAUTION
- Manual Holders who do not sign and return this transmittal form to Document Control on or before the required return date may be required to return their controlled manual (s) to Document Control.
Please retum to: MAINE YANKEE Document Control Center 321 Old Ferry Road Wiscasset, Maine 04578 g ;
i nfDA 9909090126 990831 'T cp I PDR ADOCK 05000309 \
H PDR
1 MYAPC f)
V The maximum probable flood flow in the Sheepscot River (Figure 2.3-2) was determined by means of a triangular hydrograph method (Reference. 2). This results in a flow at Wiscasset of 126,500 cfs (Figure 2.3-3). Due to its vast size, the water levels in the Sheepscot Bay will remain essentially unaffected by this flood flow. Therefore, a backwater curve was calculated for the Sheepscot River from the open coast to Wiscasset, assuming conservatively that none of the flow passes through Back River but that the water surface at the plant site will be the same as Wiscasset.
I It was assumed that the highest water levels would occur if the peak of the runoff coincided with the peak of the astronomical high tide and storm surge. Uniform flow was assumed with an n= 0.03, and j the area and hydraulic radius at Doggett Castle, as taken from USC&GS Chart No. 314, was used as I the mean river section. This resulted in a water slope of 0.035 feet per mile, which is equal to a total increase in water levels of only 0.4 feet.
2.3.3.2 Wave Runup and Wave Forces Wave runup on the slope above still water level is dependent on the roughness and porosity of the material composing this slope as well as peried and height. As given in Reference 3, a sandy slope is considered smooth while a rubble-mound structure or a riprap covered structure is considered rough.
p V
The slope for which wave runup was determined is covered with trees and brush. Since the trees will l break up and retard the waves in the same manner as rubble, the wave runup was determined using a slope roughness equal to the average of smooth and rough as shown in Reference 3. Figures 2.3-4, 2.3-5,2.3-6, and 2.3-7 give plans and profiles for the plant and surrounding area.
Wave runup from the significant wave at the Maine Yankee site was determined in the probable maximum hurricane to be 5.11 feet on the slope south of the turbine building and 6.68 feet on the circulating water pump house. Varying the pericd of the significant wave affects the extent of wave runup on the structures. As seen on Graph B, on Figure 2.3-8, the wave runup on the slope increases with greater wave period while the wave runup on the screen wellincreases with shorter wave period.
This condition is due to the wave runup at the screen well being a standing wave while the wave runup j on the slope is due to a breaking wave. i The probability of any wave occurring in a spectrum of waves can be determined using Bretschneider's !
Joint Distribution as found in Reference 3. Assuming that the design wave occurs during the period ,
of 2.2. hours when the winds in the probable maximum hurricane exceed 110 mph, approximately l 1,840 waves can occur. This period of maximum winds we define as the " critical period" of the i probable maximum hurricane. Using Bretschneider's Distribution, the distribution of waves with a height of 5.63 feet and a varying period is shown in Graph A of Figure 2.3-8. This graph shows that i
, Rev.14 v i DSAR 2-48 l
\
l
MYAPC O
O ~
0.6% of the waves that occur when the winds exceed 110 mph have a period of 1.7 to 2.6 seconds; accordingly, the wave runup on the circulating water pump house or slope as plotted in Graph B would have the same frequency of occurrence. Accumulative frequency of wave runup during the " critical period" has been obtained by plotting the sum of the individual frequencies as shown in Graph A versus the corresponding wave runup as shown by Graph B. This accumulative frequency of wave runup is shown in Graph C.
The wave runup frequency curve for the pump house shows that approximately 10% of the waves during the period of maximum winds would result in a wave runup equal to or greater than 6 feet. For reference purposes, design wave runup for both the slope and the pump house is indicated in Graph C. Wave runup equal to or greater than the design runup would occur during approximately 4% of the
" critical period." Should any wave runup occur that would overtop the slope or pump house, the flow rate due to overtopping would be such that the site pump house could drain. It is not considered credible that these waves would be consecutive in the wave spectrum.
Provisions are made in the design of the circulating water pump house to accept the splash and flow of wave runup to Elevation 22 feet 0. inches. This is accomplished with plates which seal the interior deck. For water to overtop the 12-inch kick plate / floodgate system inside the building, water would n have to stand above that elevation on the outside of the building; however, this is not possible. Only lC) one door of the pump house will be exposed to the runup. In addition to the precautions designed into the structure, the exposed door can always be sandbagged if runup is a problem. Equ:pment located in the circulating water pump house and the structure itself have been designed to be unaffected by the maximum water height described. Pump seals, castings and auxiliary piping all are installed with due consideration of the maximum water height.
l An investigation has been conducted to determine the forces on the outside curtain wall and the supporting floor for the service water. This investigation includes the dynamic forces of a breaking wave on the structure. The first part of the calculation assumes a wave train approaching the front face of the structure at a 30 degree angle. This angle is considered the flattest angle at which a wave of 5.63 feet could be generated due to the estuarial geometry. We have conservatively assumed the wave break at the structure. The Minikin formula (Reference 3), as modified by the approach angle and wall inclination, was used to calculate the static and dynamic forces on the exterior curtain wall of the structure. The water level in the interior of the structure was assumed to oscillate with the same period and amplitude as the incident wave. The dynamic force of this free surface rising to strike the j underside of the pump well floor was calculated by determining the momentum change in the vertical l direction. The underside of the pump well floor is flat, and thus offers no resistance to horizontal fluid f flow, which is the direction to which the velocity is converted once impingement occurs. A factor of two !
O Rev.14
(
DSAR 2-49 J
1 1
1 MYAPC O'
v design margins between the strength of the wall and the force of a breaking wave was found.
l An investigation has been carried out to examine the characteristics of waves that could be generated l across Back River from the east. Significant wave heights of 3.6 feet or less were predicted for ,
conditions of a 2,000 foot fetch length, a sustained wind speed of 110 mph, and 4 different water l surface elevations ranging from -7 feet to +15 feet (MSL). The Thijsse and Schijf method (Reference
- 4) formed the basis of these computations. Each of the four wave heights was examined according to wave-breaking criteria summarized in Reference 4 and found to be smaller than a breaking wave.
Consequently, none of the waves generated under these conditions could break. Therefore, they pose no threat to the structural integnty of the screen well curtain wall. l The new Fuel Oil Storage Facility is well back from the river bank. Wave run-up on the slope will drain back between waves and not flow around the fuel oil facility's two doors. The doors sills are at l Elevation 25 feet,1 inch, which is 5 feet,1 inch, above the highest calculated run-up. One of two vent pipe centerlines penetrates a wall at Elevation 35 feet,7-1/4 inches, while the other vent pipe centerline l l penetrates a wall at Elevation 35 feet,9 inches. The two fill pipe centerlines, which have locking caps, penetrate a wall at Elevation 21 feet, O inches. The fill pipe penetrations are grouted and sealed.
All other buildings are even more remote from the river edge and less susceptible to flooding from any j O V
cause. Nevertheless, they all are capable of being sandbagged if conditions indicated the need.
l Computations for these improbable combinations of events show that no structural damage or jeopardy j to the plant would result. Even if the waves could break against the pump house structure with I appreciably more energy, the curtain wall would not fail catastrophically, but might crack and be held in place by the reinforcing steel. The curtain wallis not required for the integrity of the remainder of the structure.
2.3.3.3 Extreme Low Water In support of original service water system design a study of the most severe combination of tide influencing conditions was made by coupling the effects of a low spring tide and the winds of the I probable maximum hurricane blowing from a northerty direction rather than southerly.
The low spring tide level is 5.2 feet below MSL at Lower Hell Gate. Wind setup calculations proceeded from the method summarized in Reference 3. An additional change in the water surface of -2.6 feet was predicted which brings the water surface elevation to -7.8 feet at the service water l
l O DSAR 2-50 Rev.14
l MYAPC
~
The maximum probable flood flow in the Sheepscot River (Figure 2.3-2) was determined by means of a triangular hydrograph method (Reference. 2). This results in a flow at Wiscasset of 126,500 cfs (Figure 2.3-3). Due to its vast size, the water levels in the Sheepscot Bay will remain essentially unaffected by this flood flow. Therefore, a backwater curve was calculated for the Sheepscot River from the open coast to Wiscasset, assuming conservatively that none of the flow passes through Back River but that the water surface at the plant site will be the same as Wiscasset.
It was assumed that the highest water levels would occur if the peak of the runoff coincided with the peak of the astronomical high tide and storm surge. Uniform flow was assumed with an n= 0.03, and the area and hydraulic radius at Doggett Castle, as taken from USC&GS Chart No. 314, was used as the mean river section.- This resulted in a water slope of 0.035 feet per mile, which is equal to a total increase in water levels of only 0.4 feet. g 2.3.3.2 Wave Runup and Wave Forces l Wave runup on the slope above still water level is dependent on the roughness and porosity of the l material composing this slope as well as period and height. As given in Reference 3, a sandy slope is considered smooth while a rubble-mound structure or a riprap covered structure is considered rough. !
The slope for which wave runup was determined is covered with trees and brush. Since the trees will l )
break up and retard the waves in the same manner as rubble, the wave runup was determined using 1 a slope roughness equal to the average of smooth and rough as shown in Reference 3. Figures 2.3-4, ;
2.3-5,2.3-6, and 2.3-7 give plans and profiles for the plant and surrounding area. l l
Wave runup from the significant wave at the Maine Yankee site was determined in the probable j maximum hurricane to be 5.11 feet on the slope south of the turbine building and 6.68 feet on the circulating water pump house. Varying the period of the significant wave affects the extent of wave runup on the structures. As seen on Graph B, on Figure 2.3-8, the wave runup on the slope increases with greater wave period while the wave runup on the screen well increases with shorter wave period.
This condition is due to the wave runup at the screen well being a standing wave while the wave runup !
cn the slope is due to a breaking wave.
The probability of any wave occurring in a spectrum of waves can be determined using Bretschneider's Joint Distribution as found in Reference 3. Assuming that the design wave occurs during the period of 2.2. hours when the winds in the probable maximum hurricane exceed 110 mph, approximately 1,840 waves can occur. This period of maximum winds we define as the " critical period" of the probable maximum hurricane. Using Bretschneider's Distribution, the distribution of waves with a height of 5.63 feet and a varying period is shown in Graph A of Figure 2.3-8. This graph shows that Rev.14 DSAR' 2-48
l l
MYAPC s- 0.6% of the waves that occur when the winds exceed 110 mph have a period of 1.7 to 2.6 seconds; accordingly, the wave runup on the circulating water pump house or slope as plotted in Graph B would l have the same frequency of occurrence. Accumulative frequency of wave runup during the " critical period" has been obtained by plotting the sum of the individual frequencies as shown in Graph A versus the corresponding wave runup as shown by Graph B. This accumulative frequency of wave runup is shown in Graph C.
The wave runup frequency curve for the pump house shows that approximately 10% of the waves during the period of maximum winds would result in a wave runup equal to or greater than 6 feet. For reference purposes, design wave runup for both the slope and the pump house is indicated in Graph C. Wave runup equal to or greater than the design runup would occur during approximately 4% of the
" critical period." Should any wave runup occur that would overtop the slope or pump house, the flow rate due to overtopping would be such that the site pump house could drain. It is not considered credible that these waves would be consecutive in the wave spectrum.
Provisions are maoe in the design of the circulating water pump house to accept the splash and flow l I
of wave runup to Elevation 22 feet 0 inches. This is accomplished with plates which seal the interior deck. For water to overtop the 12-inch kick plate / floodgate system inside the building, water would n have to stand above that elevation on the outside of the building; however, this is not possible. Only
() one door of the pump house will be exposed to the runup. In addition to the precautions designed into the structure, the exposed door can always be sandbagged if runup is a problem. Equipment located in the circulating water pump house and the structure itself have been designed to be unaffected by the maximum water height desciibed. Pump seals, castings and auxiliary piping all are installed with due consideration of the maximum water height.
An investigation has been conducted to determine the forces on the outside curtain wall and the supporting floor for the service water. This investigation includes the dynamic forces of a breaking wave on the structure. The first part of the calculation assumes a wave train approaching the front face of the structure at a 30 degree angle. This angle is considered the flattest angle at which a wave of 5.63 feet could be generated due to the estuarial geometry. We have conservatively assumed the wave break at the structure. The Minikin formula (Reference 3), as modified by the approach angle and wall inclination, was used to calculate the static and dynamic forces on the exterior curtain wall of the structure. The water level in the interior of the structure was assumed to oscillate with the same period and amplitude as the incident wave. The dynamic force of this free surface rising to strike the underside of the pump well floor was calculated by determining the momentum change in the vertical direction. The underside of the pump well floor is flat, and thus offers no resistance to horizontal fluid flow, which is the direction to which the velocity is converted once impingement occurs. A factor of two p)
'w Rev.14 DSAR 2-49
7 l
l MYAPC design margins between the strength of the wall and the force of a breaking wave was found.
An investigation has been carried out to examine the characteristics of waves that could be generated across Back River from the east. Significant wave heights of 3.6 feet or less were predicted for conditions of a 2,000 foot fetch length, a sustained wind speed of 110 mph, and 4 different water surface elevations ranging from -7 feet to +15 feet (MSL). The Thijsse and Schijf method (Reference
- 4) formed the basis of these computations. Each of the four wave heights was examined according to wave-breaking criteria summarized in Reference 4 and found to be smaller than a breaking wave.
Consequently, none of the waves generated under these conditions could break. Therefore, they pose no threat to the structuralintegrity of the screen well curtain wall.
l The new Fuel Oil Storage Facility is well back from the river bank. Wave run-up on the slope will drain back between waves and not flow around the fuel oil facility's two doors. The doors sills are at Elevation 25 feet,1 inch, which is 5 feet,1 inch, above the highest calculated run-up. One of two vent pipe centerlines penetrates a wall at Elevation 35 feet,7-1/4 inches, while the other vent pipe centerline penetrates a wall at Elevation 35 feet,9 inches. The two fill pipe centerlines, which have locking caps, penetrate a wall at Elevation 21 feet, O inches. The fill pipe penetrations are grouted and sealed.
All other buildings are even more remote from the river edge and less susceptible to flooding from any cause. Nevertheless, they all are capable of being sandbagged if conditions indicated the need.
Computations for these improbable combinations of events show that no structural damage orjeopardy to the plant would result. Even if the waves could break against the pump house structure with appreciably more energy, the curtain wall would not fait catastrophically, but might crack and be held in place by the reinforcing steel. The curtain wall is not required for the integrity of the remainder of the structure.
2.3.3.3 Extreme Low Water in support of original service water system design a study of the most severe combination of tide influencing conditions was made by coupling the effects of a low spring tide and the winds of the probable maximum hurricane blowing from a northerly direction rather than southerly.
The low spring tide level is 5.2 feet below MSL at Lower Hell Gate. Wind setup calculations proceeded from the method summarized in Reference 3. An additional change in the water surface of -2.6 feet was predicted which brings the water surface elevation to -7.8 feet at the service water O
V DSAR 2-50 Rev.14 J
I I
MYAPC lO j U The maximum probable flood flow in the Sheepscot River (Figure 2.3-2) was determined by means of a triangular hydrograph method (Reference. 2). This results in a flow at Wiscasset of 126,500 cfs (Figure 2.3-3). Due to its vast size, the water levels in the Sheepscot Bay will remain essentially unaffected by this flood flow. Therefore, a backwater curve was calculated for the Sheepscot River from the open coast to Wiscasset, assuming conservatively that none of the flow passes through Back River but that the water surface at the plant site will be the same as Wiscasset.
It was assumed that the highest water levels would occur if the peak of the runoff coincided with the peak of the astronomical high tide and storm surge. Uniform flow was assumed with an n= 0.03, and the area and hydraulic radius at Doggett Castle, as taken from USC&GS Chart No. 314, was used as the mean river section. This resulted in a water slope of 0.035 feel per mile, which is equal to a total increase in water levels of only 0.4 feet.
2.3.3.2 Wave Runup and Wave Forces Wave runup cn the slope above still water level is dependent on the roughness and porosity of the material composing this slope as well as period and height. As given in Reference 3, a sandy sl ope is considered smooth while a rubble-mound structure or a riprap covered structure is considered rough.
(' The slope for which wave runup was determined is covered with trees and brush. Since the trees will break up and retard the waves in the same manner as rubble, the wave runup was determined using a slope roughness equal to the average of smooth and rough as shown in Reference 3. Figures 2.3-4, 2.3-5,2.3-6, and 2.3-7 give plans and profiles for the plant and surrounding area.
Wave runup from the significant wave at the Maine Yankee site was determined in the probable maximum hurricane to be 5.11 feet on the slope south of the turbine building and 6.68 feet on the circulating water pump house. Varying the period of the significant wave affects the extent of wave runup on the structures. As seen on Graph B, on Figure 2.3-8, the wave runup on the slope increases with greater wave period while the wave runup on the screen well increases with shorter wave period.
This condition is due to the wave runup at the screen well being a standing wave while the wave runup on the slope is due to a breaking wave.
The probability of any wave occurring in a spectrum of waves can be determined using Bretschneiders Joint Distribution as found in Reference 3. Assuming that the design wavo occurs during the period of 2.2. hours when the winds in the probable maximum hurricane exceed 110 mph, approximately 1,840 waves can occur. This period of maximum winds we define as the " critical period" of the probable maximum hurricane. Using Bretschneider's Distribution, the distribution of waves with a height of 5.63 feet and a varying period is shown in Graph A of Figure 2.3-8. This graph shows that p Rev.14 DSAR 2-48
~
( l V 0.6% of the waves that occur when the winds exceed 110 mph have a period of 1.7 to 2.6 seconds; accordingly, the wave runup on the circulating water pump house or slope as plotted in Graph B would have the same frequency of occurrence. Accumutative frequency of wave runup during the " critical period" has been obtained by plotting the sum of the individual frequencies as shown in Graph A versus the corresponding wave runup as shown by Graph B. This accumulative frequency of wave runup is shown in Graph C.
The wave runup frequency curve for the pump house shows that approximately 10% of the waves during the period of maximum winds would result in a wave runup equal to or greater than 6 feet. For reference purposes, design wave runup for both the slope and the pump house is indicated in Graph C. Wave runup equal to or greater than the design runup would occur during approximately 4% of the
" critical period." Should any wave runup occur that would overtop the slope or pump house, the flow rate due to overtopping would be such that the site pump house could drain. It is not considered credible that these waves would be consecutive in the wave spectrum.
Provisions are made in the design of the circulating water pump house to accept the splash and flow of wave runup to Elevation 22 feet 0 inches. This is accomplished with plates which seal the interior deck. For water to overtop the 12-inch kick plate / floodgate system inside the building, water would
- have to stand above that elevation on the outside of the building; however, this is not possible. Only (u,b one door of the pump house will be exposed to the runup. In addition to the precautions designed into the structure, the exposed door can always be sandbagged if runup is a problem. Equipment located in the circulating water pump house and the structure itself have been designed to be unaffected by the maximum water height described. Purnp seals, castings and auxiliary piping all are installed with due consideration of the maximum water height. l An investigation has been conducted to determine the forces on the outside curtain wall and the I
supporting floor for the service water. This investigation includes the dynamic forces of a breaking wave on the structure. The first part of the calculation assumes a wave train approaching the front face of the structure at a 30 degree angle. This angle is considered the flattest angle at which a wave of 5.63 feet could be generated due to the estuarial geometry. We have conservatively assumed the wave break at the structure. The Minikin formula (Reference 3), as modified by the approach angle and wall inclination, was used to calculate the static and dynamic forces on the exterior curtain wall of the structure. The water level in the interior of the structure was assumed to oscillate with the same period and amplitude as the incident wave. The dynamic force of this free surface rising to strike the underside of the pump well floor was calculated by determining the momentum change in the vertical direction. The underside of the pump well floor is flat, and thus offers no resistance to horizontal fluid flow, which is the direction to which the velocity is converted once impingement occurs. A factor of two O Rev.14 L)
DSAR 2-49
l.
c MYAPC
(
C') design margins between the strength of the wall and the force of a breaking wave was found.
.An investigation has been carried out to examine the characteristics of waves that could be generated across Back River from the east. Significant wave heights of 3.6 feet or less were predicted for conditions of a 2,000 foot fetch length, a sustained wind speed of 110 mph, and 4 different water surface elevations ranging from -7 feet to +15 feet (MSL). The Thijsse and Schijf method (Reference
- 4) formed the basis of these computations. Each of the four wave heights was examined according '
to wave-breaking criteria summarized in Reference 4 and found to be smaller than a breaking wave.
Consequently, none of the waves generated under these conditions could break. Therefore, they pose no threat to the structural integrity of the screen well curtain wall.
The new Fuel Oil Storage Facility is well back from the river bank. Wave run-up on the slope will drain back between waves and not flow around the fuel oil facility's two doors. The doors sills are at Elevation 25 feet,1 inch, which is 5 feet,1 inch, above the highest calculated run-up. One of two vent pipe centerlines penetrates a wall at Elevation 35 feet,7-1/4 inches, while the other vent pipe centerline penetrates a wall at Elevation 35 feet,9 inches. The two fill pipe centerlines, which have locking caps, penetrate a wall at Elevation 21 feet O inches. The fill pipe penetrations are grouted and sealed. l All other buildings are even more remote from the river edge an.11ess susceptible to flooding from any h) v cause. Nevertheless, they all are capable of being sandbagged if conditions indicated the need.
Computations for these improbable combinations of events show that no structural damage or jeopardy to the plant would result. Even if the waves could break against the pump house structure with appreciably more energy, the curtain wall would not fait catastrophically, but might crack and be held in place by the reinforcing steel. The curtain wall is not required for the integrity of the remainder of the structure.
2.3.3.3 Extreme Low Water in support of original service water system design a study of the most severe combination of tide influencing conditions was made by coupling the effects of a low spring tide and the winds of the probable maximum hurricane blowing from a northerly direction rather than southerly.
The low spring tide level is 5.2 feet below MSL at Lower Hell Gate. Wind setup calculations proceeded from the method summarized in Reference 3. An additional change in the water surface of -2.6 feet was predicted which brings the water surface elevation to -7.8 feet at the service water C)
V DSAR 2-50 Rev.14
s n MYAPC i i U The maximum probable flood flow in the Sheepscot River (Figure 2.3-2) was determined by means of a triangular hydrograph method (Reference. 2). This results in a flow at Wiscasset of 126,500 cfs (Figure 2.3-3). Due to its vast size, the water levels in the Sheepscot Bay will remain essentially unaffected by this flood flow. Therefore, a backwater curve was calculated for the Sheepscot River from the open coast to Wiscasset, assuming conservatively that none of the flow passes through Back River but that the water surface at the plant site will be the same as Wiscasset.
It was assumed that the highest water levels would occur if the peak of the runoff coincided with the peak of the astronomical high tide and storm surge. Uniform flow was assumed with an n= 0.03, and the area and hydraulic radius at Doggett Castle, as taken from USC&GS Chart No. 314, was used as the mean river section. This resulted in a water slope of 0.035 feet per mile, which is equal to a total increase in water levels of only 0.4 feet.
1 2.3.3.2 Wave Runup and Wave Forces
)
Wave runup on the slope above still water level is dependent on the roughness and porosity of the material composing this slope as well as period and height. As given in Reference 3, a sandy slope is considered smooth while a rubble-mound structure or a riprap covered structure is considered rough.
l(' The slope for which wave runup was determined is covered with trees and brush. Since the trees will
'k break up and retard the waves in the same manner as rubble, the wave runup was determined using i a slope roughness equal to the average of smooth and rough as shown in Reference 3. Figures 2.3-4, 2.3-5,2.3-6, and 2.3-7 give plans and profiles for the plant and surrounding area.
Wave runup from the significant wave at the Maine Yankee site was determined in the probable maximum hurricane to be 5.11 feet on the slope south of the turbine building and 6.68 feet on the l circulating water pump house. Varying the period of the significant wave affects the extent of wave runup on the structures. As seen on Graph B, on Figure 2.3-8, the wave runup on the slope increases l
with greater wave period while the wave runup on the screen well increases with shorter wave period.
This condition is due to the wave runup at the screen well being a standing wave while the wave runup on the slope is due to a breaking wave.
l The probability of any wave occurring in a spectrum of waves can be determined using Bretschneider's Joint Distribution as found in Reference 3. Assuming that the design wave occurs during the period of 2.2. hours when the winds in the probable maximum hurricane exceed 110 mph, approximately 1,840 waves can occur. This period of maximum winds we define as the " critical period" of the probable maximum hurricane. Using Bretschneider's Distribution, the distribution of waves with a height of 5.63 feet and a varying period is shown in Graph A of Figure 2.3-8. This graph shows that g Rev.14
%s)
DSAR 2-48
l MYAPC h
d 0.6% of the waves that occur when the winds exceed 110 mph have a period of 1.7 to 2.6 seconds; accordingly, the wave runup on the circulating water pump house or slope as plotted in Graph B would have the same frequency of occurrence. Accumulative frequency of wave runup during the " critical period" has been obtained by plotting the sum of the individual frequencies as shown in Graph A versus the corresponding wave runup as shown by Graph B. This accumulative frequency of wave runup is shown in Graph C.
The wave runup frequency curve for the pump house shows that approximately 10% of the waves during the period of maximum winds would result in a wave runup equal to or greater than 6 feet. For reference purposes, design wave runup for both the slope and the pump house is indicated in Graph C. Wave runup equal to or greater than the design runup would occur during approximately 4% of the
" critical period." Should any wave runup occur that would overtop the slope or pump house, the flow rate due to overtopping would be such that the site pump house could drain. It is not considered credible that these waves would be consecutive in the wave spectrum.
Provisions are made in the design of the circulating water pump house to accept the splash and flow of wave runup to Elevation 22 feet 0 inches. This is accomplished with plates which seal the interior deck. For water to overtop the 12-inch kick plate / floodgate system inside the building, water would p have to stand above that elevation on the outside of the building; however, this is not possible. Only C/ one door of the pump house will be exposed to the runup. In addition to the precautions designed into the structure, the exposed door can always be sandbagged if runup is a problem. Equipment located in the circulating water pump house and the structure itself have been designed to be unaffected by the maximum water height described. Pump seals, castings and auxiliary piping all are installed with due consideration of the maximum water height.
An investigation has been conducted to determine the forces on the outside curtain wall and the supporting floor for the service water. This investigation includes the dynamic forces of a breaking wave on the structure. The first part of the calculation assumes a wave train approaching the front face of the structure at a 30 degree angle. This angle is considered the flattest angle at which a wave of 5.63 feet could be generated due to the estuarial geometry. We have conservatively assumed the wave break at the structure. The Minikin formula (Reference 3), as modified by the approach angle and wall inclination, was used to calculate the static and dynamic forces on the exterior curtain wall of I
the structure. The water level in the interior of the structure was assumed to oscillate with the same period and amplitude as the incident wave. The dynamic force of this free surface rising to strike the underside of the pump well floor was calculated by determining the momentum change in the vertical direction. The underside of the pump well floor is flat, and thus offers no resistance to horizontal fluid j flow, which is the direction to which the velocity is converted once impingement occurs. A factor of two Rev.14 l DSAR 2-49 1
l
. design margins between the strength of the wall and the force of a breaking wave was found.
An investigation has been carried out to examine the characteristics of waves that could be generated across Back River from the east. Significant wave heights of 3.6 feet or less were predicted for
~ conditions of a 2,000 foot fetch length,'a sustained wind spee' d of 110 mph, and 4 different water
- surface elevations ranging from -7 feet to +15 feet (MSL). The Thijsse and Schijf method (Reference
- 4) . formed the basis of these computations. Each of the four wave heights was examined according
' to wave-breaking criteria summarized in Reference 4 and found to be smaller than a breaking wave.
Consequently, none of the waves generated unde,- these conditions could break. Therefore, they pose no threat to the structural integrity of the screen well curtain wall. j The new Fuel Oil Storage Facility is well back from the river bank. Wave run-up on the slope will drain back between waves and not flow around the fuel oil facility's two doors. The doors sills are at Elevation 25 feet,1 inch, which is 5 feet,1 inch, above the highest calculated run-up. One of two vent
. pipe centerlines penetrates a wall at Elevation 35 feet,7-1/4 inches, while the other vent pipe centerline penetrates a wall at Elevation 35 feet,9 inches. The two fill pipe centerlines, which have locking caps, i penetrate a wall'at Elevation 21 feet,0 inches. The fill pipe penetrations are grouted and sealed.
I All other buildings are even more remote from the river edge and less susceptible to flooding from any f Q
b cause. Nevertheless, they all are capable of being sandbagged if conditions indicated the need. I Computations for these improbable combinations of events show that no structural damage or jeopardy to the plant would result. Even if the waves could break against the pump house structure with appreciably more energy, the curtain wall would not fail catastrophically, but might crack and be held in place by the reinforcing steel. The curtain wall is not required for the integrity of the remainder of the structure.
2.3.3.3 Extreme Low Water in support of original service water system design a study of the most severe combination of tide influencing conditions was made by coupling the effects of a low spring tide and the winds of the probable maximum hurricane blowing from a northerly direction rather than southerly.
l The low spring tide level is 5.2 feet below MSL at Lower Hell Gate. Wind setup calculations proceeded from the method summarized in Reference 3. An additional change in the water surface of-2.6 feet was predicted which brings the water surface elevation to -7.8 feet at the service water O DSAR 2-50 Rev.14 i
1 l
MYAPC p
b The maximum probable flood flou in the Sheepscot River (Figure 2.3-2) was determined by means of a triangular hydrograph method (Reference. 2). This results in a flow at Wiscasset of 126,500 cfs (Figure 2.3-3). Due to its vast size, the water levels in the Sheepscot Bay will remain essentially unaffected by this flood flow. Therefore, a backwater curve was calculated for the Sheepscot River from the open coast to Wiscasset, assuming conservatively that none of the flow passes through Back River but that the water surface at the plant site will be the same as Wiscasset.
It was assumed that the highest water levels would occur if the peak of the runoff coincided with the peak of the astronomical high tide and storm surge. Uniform flow was assumed with an n= 0.03, cnd the area and hydraulic radius at Doggett Castle, as taken from USC&GS Chart No. 314, was used as th mean river section. This resulte'd in a water slope of 0.035 feet per mile, which is equal to a total increase in water levels of only 0.4 feet.
2.3.3.2 Wave Runup and Wave Forces Wave runup on the slope above still water level is dependent on the roughness and porosity of the material composing this slope as well as period and height. As given in Reference 3, a sandy slope is considered smooth while a rubble-mound structure or a riprap covered structure is considered rough.
/G The slope for which wave runup was determined is covered with trees and brush. Since the trees will U break up and retard the waves in the same manner as rubble, the wave runup was determined using a slope roughness equal to the average of smooth and rough as shown in Reference 3. Figures 2.3-4, 2.3-5,2.3-6, and 2.3-7 give plans and profiles for the plant and surrounding area.
Wave runup from the significant wave at the Maine Yankee site was determined in the probable maximum hurricane to be 5.11 feet on the slope south of the turbine building and 6.68 feet on the circulating water pump house. Varying the period of the significant wave affects the extent of wave runup on the structures. As seen on Graph B, on Figure 2.3-8, the wave runup on the slope increases with greater wave period while the wave runup on the screen wellincreases with shorter wave period.
This condition is due to the wave runup at the screen well being a standing wave while the wave runup on the slope is due to a breaking wave.
The probability of any wave occurring in a spectrum of waves can be determined using Bretscnneider's Joint Distribution as found in Reference 3. Assuming that the design wave occurs during the period of 2.2. hours when the winds in the probable maximum hurricane exceed 110 mph, approximately 1,840 waves can occur. This period of maximum winds we define as the " critical period" of the probable maximum hurricane. Using Bretschneider's Distribution, the distribution of waves with a height of 5.63 feet and a varying period is shown in Graph A of Figure 2.3-8. This graph shows that g)
L Rev.14 DSAR 2-48
,, MYAPC lV) 0.6% of the waves that occur when the winds exceed 110 mph have a period of 1.7 to 2.6 seconds; accordingly, the wave runup on the circulating water pump house or slope as plotted in Graph B would have the same frequency of occurrence. Accumulative frequency of wave runup during the " critical period" has been obtained by plotting the sum of the individual frequencies as shown in Graph A versus the corresponding wave runup as shown by Graph B. This accumulative frequency of wave runup is shown in Graph C.
The wave runup frequency curve for the pump house shows that approximately 10% of the waves during the period of maximum winds would result in a wave runup equal to or greater than 6 feet. For reference purposes, design wave runup for both the slope and the pump house is indicated in Graph C. Wave runup equal to or greater than the design runup would occur during approximately 4% of the
" critical period." Should any wave runup occur that would overtop the slope or pump house, the flow rate due to overtopping would be such that the site pump house could drain. It is not considered credible that these waves would be consecutive in the wave spectrum.
Provisions are made in the design of the circulating water pump house to accept the splash and flow of wave runup to Elevation 22 feet 0 inches. This is accomplished with plates which seal the interior deck. For water to overtop the 12-inch kick plate / floodgate system inside the building, water would have to stand above that elevation on the outside of the building; however, this is not possible. Only V one door of the pump house will be exposed to the runup. In addition to the precautions designed into the structure, the exposed door can always be sandbagged if runup is a problem. Equipment located in the circulating water pump house and the structure itself have been designed to be unaffected by the maximum water height described. Pump seals, castings and auxiliary piping all are installed with due consideration of the maximum water height.
An investigation has been conducted to determine the forces on the outside curtain wall and the supporting floor for the service water. This investigation includes the dynamic forces of a breaking wave on the structure. The first part of the calculation assumes a wave train approaching the front face of the structure at a 30 degree angle. This angle is considered the flattest angle at which a wave of 5.63 feet could be generated due to the estuarial geometry. We have conservatively assumed the wave break at the structure. The Minikin formula (Reference 3), as modified by the approach angle and wallinclination, was used to calculate the static and dynamic forces on the exterior curtain wall of the structure. The water levelin the interior of the structure was assumed to oscillate with the same period and amplitude as the incident wave. The dynamic force of this free surface rising to strike the underside of the pump well floor was calculated by determining the momentum change in the vertical direction. The underside of the pump well floor is flat, and thus offers no resistance to horizontal fluid flow, which is the direction to which the velocity is converted once impingement occurs. A factor of two Rev.14
(]
V DSAR 2-49
l MYAPC l design margins between the strength of the wall and the force of a breaking wave was found.
An investigation has been carried out to examine the characteristics of waves that could be generated i across Back River from the east. Significant wave heights of 3.6 feet or less were predicted for conditions of a 2,000 foot fetch length, a sustained wind speed of 110 mph, and 4 different water surface elevations ranging from -7 feet to +15 feet (MSL). The Thijsse and Schijf method (Reference
- 4) formed the basis of these computations. Each of the four wave heights was examined according to wave-breaking enteria summarized in Reference 4 and found to be smaller than a breaking wave. J l Consequently, none of the waves generated under these conditions could break. Therefore, they pose l
l no threat to the structural integrity of the screen well curtain wall.
The new Fuel Oil Storage Facility is well back from the river bank. Wave run-up on the slope will drain back between waves and not flow around the fuel oil facility's two doors. The doors sills are at Elevation 25 feet,1 inch, which is 5 feet,1 inch, above the highest calculated run-up. One of two vent !
l pipe centerlines penetrates a wall at Elevation 35 feet,7-1/4 inches, while the other vent pipe centerline l penetrates a wall at Elevation 35 feet,9 inches. The two fill pipe centerlines, which have locking caps, l penetrate a wall at Elevation 21 feet, O inches. The fill pipe penetrations are grouted and sealed.
All other buildings are even more remote from the river edge and less susceptible to flooding from any cause. Nevertheless, they all are capable of being sandbagged if conditions indicated the need.
Computations for these improbable combinations of events show that no structural damage or jeopardy to the plant would result. Even if the waves could break against the pump house structure with appreciably more energy, the curtain wall would not fait catastrophically, but might crack and be held j in place by the reinforcing steel. The curtain wall is not required for the integrity of the remainder of the structure. !
l 2.3.3.3 Extreme Low Water l l
l In support of original service water system design a study of the most severe combination of tide influencing conditions was made by coupling the effects of a low spring tide and the winds of the probable maximum hurricane blowing from a northerly direction rather than southerly.
The low spring tide level is 5.2 feet below MSL at Lower Hell Gate. Wind setup calculations proceeded from the method summarized in Reference 3. An additional change in the water surface of -2.6 feet was predicted which brings the water surface elevation to -7.8 feet at the service water
'O DSAR 2-50 Rev.14 l
l
MYAPC q
V The maximum probable flood flow in the Sheepscot River (Figure 2.3-2) was determined by means of a triangular hydrograph method (Reference. 2). This results in a flow at Wiscasset of 126,500 cfs (Figure 2.3-3). Due to its vast size, the water levels in the Sheepscot Bay will remain essentially unaffected by this flood flow. Therefore, a backwater curve was calculated for the Sheepscot River from the open coast to Wiscasset, assuming conservatively that none of the flow passes through Back River but that the water surface at the plant site will be the same as Wiscasset.
It was assurned that the highest water leveis would occur if the peak of the runoff coincided with the peak of the astronomical high tide and storm surge. Uniform flow was assumed with an n= 0.03, and the area and hydraulic radius at Doggett Castle, as taken from USC&GS Chart No. 314, was used as the mean river section. This resulted in a water slope of 0.035 feet per mile, which is equal to a total increase in water levels of only 0.4 feet.
2.3.3.2 Wave Runup and Wave Forces Wave runup on the slope above still water level is dependent on the roughness and porosity of the material composing this slope as well as period and height. As given in Reference 3, a sandy slope is considered smooth while a rubble-mound structure or a riprap covered structure is considered rough.
N The slope for which wave runup was determined is covered with trees and brush. Since the trees will (d break up and retard the waves in the same manner as rubble, the wave runup was determined using a slope roughness equal to the average of smooth and rough as shown in Reference 3. Figures 2.3-4, 2.3-5,2.3-6, and 2.3-7 give plans and profiles for the plant and surrounding area.
Wave runup from the significant wave at the Maine Yankee site was determined in the probable maximum hurricane to be 5.11 feet on the slope south of the turbine building and 6.68 feet on the circulating water pump house. Varying the period of the s gnificant wave affects the extent of wave runup on the structures. As seen on Graph B, on Figure 2.3-8, the wave runup on the slope increases with greater wave period while the wave runup on the screen well increases with shorter wave period.
This condition is due to the wave runup at the screen well being a standing wave while the wave runup on the slope is due to a breaking wave.
The probability of any wave occurring in a spectrum of waves can be determined using Bretschneider's Joint Distribution as found in RrJerence 3. Assuming that the design wave occurs during the period of 2.2. hours when the windu ir the probable maximum hurricane exceed 110 mph, approximately 1,840 waves can occur. This period of maximum winds we define as the " critical period" of the probable maximum hurricans. Using Bretschneider's Distribution, the distribution of waves with a height of 5.63 feet and a varying period is shown in Graph A of Figure 2.3-8. This graph shows that Rev.14
)
DSAR 2-48
I 7
/
V 0.6% of the waves that occur when the winds exceed 110 mph have a period of 1.7 to 2.6 seconds; accordingly, the wave runup on the circulating water pump house or slope as plotted in Graph B would have the same frequency of occurrence. Accumulative frequency of wave runup during the " critical period" has been obtained by plotting the sum of the individual frequencies as shown in Graph A versus the corresponding wave runup as shown by Graph B. This accumulative frequency of wave runup is shown in Graph C.
The wave runup frequency curve for the pump house shows that approximately 10% of the waves during the period of maximum winds would result in a wave runup equal to or greater than 6 feet. For reference purposes, design wave runup for both the slope and the pump house is indicated in Graph C. Wave runup equal to or greater than the design runup would occur during approximately 4% of the
" critical period." Should any wave runup occur that would overtop the slope or pump house, the flow rate due to overtopping would be such that the site pump house could drain. It is not considered credible that these waves would be consecutive in the wave spectrum.
Provisions are made in the design of the circulating water pump house to accept the splash and flow of wave runup to Elevation 22 feet 0 inches. This is accomplished with plates which seal the interior deck. For water to overtop the 12-inch kick plate / floodgate system inside the building, water would
, have to stand above that elevation on the outside of the building; however, this is not possible. Only V one door of the pump house will be exposed to the runup. In addition to the precautions designed into the structure, the exposed door can always be sandbagged if runup is a problem. Equipment located in the circulating water pump house and the structure itself have been designed to be unaffected by the maximum water height described. Pump seals, castings and auxiliary piping all are installed with due consideration of the maximum water height.
An investigation has been conducted to determine the forces on the outside curtain wall and the supporting floor for the service water. This investigation includes the dynamic forces of a breaking wave on the structure. The first part of the calculation assumes a wave train approaching the front face of the structure at a 30 degree angle. This angle is considered the flattest angle at which a wave of 5.63 feet could be generated due to the estuarial geometry. We have conservatively assumed the wave break at the structure. The Minikin formula (Reference 3), as modified by the approach angle and wall inclination, was used to calculate the static and dynamic forces on the exterior curtain wall of the structure. The water level in the interior of the structure was assumed to oscillate with the same period and amplitude as the incident wave. The dynamic force of this free surface rising to strike the underside of the pump well floor was calculated by determining the momentum change in the vertical direction. The underside of the pump well floor is flat, and thus offers no resistance to horizontal fluid flow, which is the direction to which the velocity is converted once impingement occurs. A factor of two p)
L Rev.14 DSAR 2-49
MYAPC p
C/ design margins between the strength of the wall and the force of a breaking wave was found.
l An investigation has been carried out to examine the characteristics of waves that could be generated j across Back River from the east. Significant wave heights of 3.6 feet or less were predicted for conditions of a 2,000 foot fetch length, a sustained wind speed of 110 mph, and 4 different water surface elevations ranging from -7 feet to +15 feet (MSL). The Thijsse and Schijf method (Reference
- 4) formed the basis of these computations. Each of the four wave heights was examined according to wave-breaking criteria summarized in Reference 4 and found to be smaller than a breaking wave.
Consequently, none of the waves generated under these conditions could break. Therefore, they pose no threat to the structural integrity of the screen well curtain wall.
The new Fuel Oil Storage Facility is well back from the river bank. Wave run-up on the slope will drain back between waves and not flow around the fuel oil facility's two doors. The doors sills are at Elevation 25 feet,1 inch, which is 5 feet,1 inch, above the highest calculated run-up. One of two vent pipe centerlines penetrates a wall at Elevation 35 feet,7-1/4 inches, while the other vent pipe centerline penetrates a wall at Elevation 35 feet,9 inches. The two fill pipe centerlines, which have locking caps, penetrate a wall at Elevation 21 feet,0 inches. The fill pipe penetrations are grouted and sealed.
All other buildings are even more remote from the river edge and less susceptible to flooding from any A cause. Nevertheless, they all are capable of being sandbagged if conditions indicated the need.
V Computations for these improbable combinations of events show that no structural damage or jeopardy to the plant would result. Even if the waves could break against the pump house structure with appreciably more energy, the curtain wall would not fail catastrophically, but might crack and be held in place by the reinforcing steel. The curtain wall is not required for the integrity of the remainder of the structure.
2.3.3.3 Extreme Low Water in support of original service water system design a study of the most severe combination of tide influencing conditions was made by coupling the effects of a low spring tide and the winds of the probable maximum hurricane blowing from a northerly direction rather than southerly.
The low spring tide level is 5.2 feet below MSL at Lower Hell Gate. Wind setup calculations proceeded from the method summarized in Reference 3. An additional change in the water surface of -2.6 feet was predicted which brings the water surface elevation to -7.8 feet at the service water C\
DSAR 2-50 Rev.14
, MYAPC V The maximum probable flood flow in the Sheepscot River (Figure 2.3-2) was determined by means of a triangular hydrograph method (Reference. 2). This results in a flow at Wiseasset of 126,500 cfs (Figure 2.3-3). Due to its vast size, the water levels in the Sheepscot Bay will remain essentially unaffected by this flood flow. Therefore, a backwater curve was calculated for the Sheepscot River from the open coast to Wiscasset, assuming conservatively that none of the flow passes through Back River but that the water surface at the plant site will be .he same as Wiscasset.
It was assumed that the highest water levels would occur if the peak of the runoff coincided with the peak of the astronomical high tide and storm surge. Uniform flow was assumed with an n= 0.03, and the area and hydraulic radius at Doggett Castle, as taken from USC&GS Chart No. 314, was used as the mean river section. This resulted in a water slope of 0.035 feet per mile, which is equal to a total increase in water levels of only 0.4 feet.
2.3.3.2 Wave Runup and Wave Forces Wave runup on the slope above still water level is dependent on the roughness and porosity of the material composing this slope as well as period and height. As given in Reference 3, a sandy slope is considered smooth while a rubble-mound structure or a riprap covered structure is considered rough.
(T The slope for which wave runup was determined is covered with trees and brush. Since the trees will kJ break up and retard the waves in the same manner as rubble, the wave runup was determined using a slope roughness equal to the average of smooth and rough as shown in Reference 3. Figures 2.3-4, 2.3-5,2.3-6, and 2.3-7 give plans and profiles for the plant and surrounding area.
Wave runup from the significant wave at the Maine Yankee site was determined in the probable maximum hurricane to be 5.11 feet on the slope south of the turbine building and 6.68 feet on the circulating water pump house. Varying the period of the significant wave affects the extent of wave runup on the structures. As seen on Graph B, on Figure 2.3-8, the wave runup on the slope increases with greater wave period while the wave runup on the screen well increases with shorter wave period.
This condition is due to the wave runup at the screen well being a standing wave while the wave runup on the slope is due to a breaking wave.
The probability of any wave occurring in a spectrum of waves can be determined using Bretschneider's Joint Distribution as found in Reference 3. Assuming that the design wave occurs during the period of 2.2. hours when the winds in the probable maximum hurricane exceed 110 mph, approximately 1,840 waves can occur. This period of maximum winds we define as the " critical period" of the probable maximum hurricane. Using Bretschneider's Distribution, the distribution of waves with a height of 5.63 feet and a varying period is shown in Graph A of Figure 2.3-8. This graph shows that g Rev.14 l
DSAR 2-48 i
i
MYAPC lV) 0.6% of the waves that occur when the winds exceed 110 mph have a period of 17 to 2.6 seconds, accordingly, the wave runup on the circulating water pump house or slope as plotted in Graph B would l
have the same frequency of occurrence. Accumulative frequency of wave runup during the " critical period" has been obtained by plotting the sum of the individual frequencies as shown in Graph A versus the corresponding wave runup as shown by Graph B. This accumulative frequency of wave runup is shown in Graph C.
The wave runup frequency curve for the pump house shows that approximately 10% of the waves during the period of maximum winds would result in a wave runup equal to or greater than 6 feet. For reference purposes, design wave runup for both the slope and the pump house is indicated in Graph C. Wave runup equal to or greater than the design runup would occur during approximately 4% of the
" critical period." Should any wave runup occur that would overtop the slope or pump house, the flow rate due to overtopping would be such that the site pump house could drain. It is not considered credible that these waves would be consecutive in the wave spectrum.
Provisions are made in the design of the circulating water pump house to accept the splash and flow of wave runup to Elevation 22 feet 0 inches. This is accomplished with plates which seal the interior deck. For water to overtop the 12-inch kick plate / floodgate system inside the building, water would
- have to stand above that elevation on the outside of the building; however, this is not possible. Only
/
C one door of the pump house will be exposed to the runup. In addition to the precautions designed into the structure, the exposed door can always be sandbagged if runup is a problem. Equipment located in the circulating water pump house and the structure itself have been designed to be unaffected by the maximum water height described. Pump seals, castings and auxiliary piping all are installed with due consideration of the maximum water height.
An investigation has been conducted to determine the forces on the outside curtain wall and the supporting floor for the service water. This investigation includes the dynamic forces of a breaking wave on the structure. The first part of the calculation assumes a wave train approaching the front face of the structure at a 30 degree angle. This angle is considered the flattest angle at which a wave of 5.63 feet could be generated due to the estuarial geometry. We have conservatively assumed the wave break at the structure. The Minikin formula (Reference 3), as modified by the approach angle and wall inclination, was used to calculate the static and dynamic forces on the exterior curtain wall of the structure. The water level in the interior of the structure was assumed to oscillate with the same period and amplitude as the incident wave. The dynamic force of this free surface rising to strike the underside of the pump well floor was calculated by determining the momentum change in the vertical direction. The underside of the pump well floor is flat, and thus offers no resistance to horizontal fluid flow, which is the direction to which the velocity is convetted once impingement occurs. A factor of two p V Rev.14 DSAR 2-49
l-
{
MYAPC '
O d esign margins between the strength of the wall and the force of a breaking wave was found.
An investigation has been carried out to examine the characteristics of waves that could be generated across Back River from the east. Significant wave heights of 3.6 feet or less were predicted for conditions of a 2,000 foot fetch length, a sustained wind speed of 110 mph, and 4 different water surface elevations ranging from -7 feet to +15 feet (MSL). The Thijsse and Schijf method (Reference
- 4) formed the basis of these computations. Each of the four wave heights was examined according to wave-breaking criteria summarized in Reference 4 and found to be smaller than a breaking wave. I Consequently, none of the waves generated under these conditions could break. Therefore, they pose no threat to the structural integrity of the screen well curtain wall.
The new Fuel Oil Storage Facility is well back from the river bank. Wave run-up on the slope will drain back between waves and not flow around the fuel oil facility's two doors. The doors sills are at Elevation 25 feet,1 inch, which is 5 feet 1 inch, above the highest calculated run-up. One of two vent l
pipe centerlines penetrates a wall at Elevation 35 feet, 7-1/4 inches, while the other vent pipe centerline
{
penetrates a wall at Elevation 35 feet,9 inches. The two fill pipe centerlines, which have locking caps, penetrate a wall at Elevation 21 feet,0 inches. The fill pipe penetrations are grouted and sealed.
All other buildings are even more remote from the river edge and less susceptible to flooding from any f)
%J cause. Nevertheless, they all are capable of being sandbagged if conditions indicated the need.
I Computations for these improbable combinations of events show that no structural damage or jeopardy j to the plant would result. Even if the waves could break against the pump house structure with
]
)
appreciably more energy, the curtain wall would not fail catastrophically, but might crack and be held in place by the reinforcing steel. The curtain wall is not required for the integrity of the remainder of the structure. )
2.3.3.3 Extreme Low Water In support of original service water system design a study of the most severe combination of tide influencing conditions was made by coupling the effects of a low spring tide and the winds of the probable maximum hurricane blowing from a northerly direction rather than southerly.
The low spring tide level is 5.2 feet below MSL at Lower Hell Gate. Wind setup calculations proceeded from the method summarized in Reference 3. An additional change in the water surface of -2.6 feet was predicted which brings the water surface elevation to -7.8 feet at the service water t
I tO V
l DSAR 2-50 Rev.14
l MYAPC
(\
U The maximum probable flood flow in the Sheepscot River (Figure 2.3-2) was determined by means of a triangular hydrograph method (Reference. 2). This results in a flow at Wiscasset of 126,500 cfs (Figure 2.3-3). Due to its vast size, the water levels in the Sheepscot Bay will remain essentially unaffected by this flood flow. Therefore, a backwater cuive was calculated for the Sheepscot River from the open coast to Wiscasset, assuming conservatively that none of the flow passes through Back River but that the water surface at the plant site will be the sarne as Wiscasset.
it was assumed that the highest water levels would occur if the peak of the runoff coincided with the peak of the astronomical high tide and storm surge. Uniform flow was assumed with an n= 0.03, and the area and hydraulic radius at Doggett Castle, as taken from USC&GS Chart No. 314, was used as the mean river section. This resulted in a water slope of 0.035 feet per mile, which is equal to a total increase in water levels of only 0.4 feet.
2.3.3.2 Wave Runup and Wave Forces Wave runup on the slope above still water levelis dependent on the roughness and porosity of the material composing this slope as well as period and height. As given in Reference 3, a sandy slope is considered smooth while a rubble-mound structure or a riprap covered structure is considered rough.
/7 The slope for which wave runup was determined is covered with trees and brush. Since the trees will U break up and retard the waves in the same manner as rubble, the wave runup was determined using a slope roughness equal to the average of smooth and rough as shown in Reference 3. Figures 2.3-4, 2.3-5,2.3-6, and 2.3-7 give plans and profiles for the plant and surrounding area.
Wave runup from the significant wave at the Maine Yankee site was determined in the probable maximum hurricane to be 5.11 feet on the slope south of the turbine building and 6.68 feet on the circulating water pump house. Varying the period of the significant wave affects the extent of wave runup on the structures. As seen on Graph B, on Figure 2.3-8, the wave runup on the slope increases with greater wave period while the wave runup on the screen well increases with shorter wave period.
This condition is due to the wave runup at the screen well being a standing wave while the wave runup on the slope is due to a breaking wave.
The probability of any wave occurring in a spectrum of waves can be determined using Bretschneider's Joint Distribution as found in Reference 3. Assuming that the design wave occurs during the period of 2.2. hours when the winds in the probable maximum hurricane exceed 110 mph, approximately 1,840 waves can occur. This period of maximum winds we define as the " critical period" of the probable maximum hurricane. Using Bretschneider's Distribution, the distribution of waves with a height of 5.63 feet and a varying period is shown in Graph A of Figure 2.3-8. This graph shows that Rev.14
)
DSAR 2-48
l MYAPC l ,
3 O 0.6% of the waves that occur when the winds exceed 110 mph have a period of 1.7 to 2.6 seconds; accordingly, the wave runup on the circulating water pump house or slope as plotted in Graph B would have the same frequency of occurrence. Accumulative frequency of wave runup during the " critical period" has been obtained by plotting the sum of the individual frequencies as shown in Graph A versus the corresponding wave runup as shown by Graph B. This accumulative frequency of wave runup is shown in Graph C.
The wave runup frequency curve for the pump house shows that approximately 10% of the waves during the period of maximum winds would result in a wave runup equal to or greater than 6 feet. For reference purposes, design wave runup for both the slope and the pump house is indicated in Graph l C. Wave runup equal to or greater than the design runup would occur during approximately 4% of the
" critical period." Should any wave runup occur that would overtop the slope or pump house, the flow rate due to overtopping would be such that the site pump house could drain. It is not considered credible that these waves 'would be consecutive in the wave spectrum.
l Provisions are made i , the design of the circulating water pump house to accept the splash and flow of wave runup to Elevation 22 feet 0 inches. This is accomplished with plates which seal the interior deck. For water to overtop the 12-inch kick plate / floodgate system inside the building, water would have to stand above that elevation on the outside of the building; however, this is not possible. Only
() one door of the pump house will be exposed to the runup. In addition to the precautions designed into the structure, the exposed door can always be sandbagged if runup is a problem. Equipment located in the circulating water pump house and the structure itself have been designed to be unaffected by the maximum water height described. Pump seals, castings and auxiliary piping all are installed with due consideration of the maximum water height.
An investigation has been conducted to determine the forces on the outside curtain wall and the supporting floor for the service water. This investigation includes the dynamic forces of a breaking !
wave on the structure. The first part of the calculation assumes a wave train approaching the front face of the structure at a 30 degree angle. This angle is considered the flattest angle at which a wave of i 5.63 feet could be generated due to the estuarial geometry. We have conservatively assumed the wave break at the structure. The Minikin formula (Reference 3), as modified by the approach angle j and wall inclination, was used to calculate the static and dynamic forces on the exterior curtain wall of !
the structure. The water levelin the interior of the structure was assumed to oscillate with the same l period and amplitude as the incident wave. The dynamic force of this free surface rising to strike the underside of the pump well floor was calculated by determining the momentum change in the vertical ]
direction. The underside of the pump well floor is flat, and thus offers no resistance to horizontal fluid flow, which is the direction to which the velocity is converted once impingement occurs. A factor of two
/G Rev.14 U
DSAR 2-49
- l design margins between the strength of the wall and the force of a breaking wave was found.
An investigation has been carried out to examine the characteristics of waves that could be generated across Back River from the east. Significant wave heights of 3.6 feet or less were predicted for conditions of a 2,000 foot fetch length, a sustained wind speed of 110 mph, and 4 different water surface elevations ranging from -7 feet to +15 feet (MSL). The Thijsse and Schijf method (Reference 1
- 4) formed the basis of these computations. Each of the four wave heights was examined according to wave-breaking criteria summarized in Reference 4 and found to be smaller than a breaking wave.
Consequently, none of the waves generated under these conditions could break. Therefore, they pose !
no threat to the structural integrity of the screen well curtain wall.
The new Fuel Oil Storage Facility is well back from the river bank. Wave run-up on the slope will drain back between waves and not flow around the fuel oil facility's two doors. The doors sills are at j Elevation 25 feet,1 inch, which is 5 feet,1 inch, above the highest calculated run-up. One of two vent I pipe centerlines penetrates a wall at Elevation 35 feet,7-1/4 inches, while the other vent pipe centerline penetrates a wall at Elevation 35 feet,9 inches. The two fill pipe centeriines, which have locking caps, l penetrate a wall at Elevation 21 feet,0 inches. The fill pipe penetrations are grouted and sealed. ]
All other buildings are even more remote from the river edge and less susceptible to flooding from any fi O
cause. Nevertheless, they all are capable of being sandbagged if conditions indicated the need.
Computations for these improbable combinations of events show that no structural damage orjeopardy to the plant would result. Even if the waves could break against the pump house structure with appreciably more energy, the curtain wall would not fail catastrophically, but might crack and be held in place by the reinforcing steel. The curtain wall is not required for the integrity of the remainder of the structure.
2.3.3.3 Extreme Low Water in support of original service water system design a study of the rnost severe combination of tide influencing conditions was made by coupling the effects of a low spring tide and the winds of the probable maximum hurricane blowing from a northerly direction rather than southerly.
The low spring tide level is 5.2 feet below MSL at Lower Hell Gate. Wind setup calculations proceeded from the method summarized in Reference 3. An additional change in the water surface of -2.6 feet was predicted which brings the water surface elevation to -7.8 feet at the service water G
b DSAR 2-50 Rev.14
1 MYAPC C) The maximum probable flood flow in the Sheepscot River (Figure 2.3-2) was determined by means of a triangular hydrograph method (Reference. 2). This results in a flow at Wiscasset of 126,500 cfs (Figure 2.3-3). Due to its vast size, the water levels in the Sheepscot Bay will remain essentially unaffected by this flood flow. Therefore, a backwater curve was calculated for the Sheepscot River from the open coast to Wiscasset, assuming conservatively that none of the flow passes through Back River but that the water surface at the plant site will be the same as Wiscasset.
It was assumed that the highest water levels would occur if the peak of the runoff coincided with the peak of the astronomical high tide and storm surge. Uniform flow was assumed with an n= 0.03, and the area and hydraulic radius at Doggett Castle, as taken from USC&GS Chart No. 314, was used as the mean river section. This resulted in a water slope of 0.035 feet per mile., which is equal to a total increase in water levels of only 0.4 feet.
2.3.3.2 Wave Runup and Wave Forces Wave runup on the slope above still water level is dependent on the roughness and porosity of the material composing this slope as well as period and height. As given in Reference 3, a sandy slope is considered smooth while a rubble-mound structure or a riprap covered structure is considered rough.
(~] The slope for which wave runup was determined is covered with trees and brush. Since the trees will b' break up and retard the waves in the same manner as rubble, the wave runup was determined using a slope roughness equal to the average of smooth and rough as shown in Reference 3. Figures 2.3-4, 2.3-5,2.3-6, and 2.3-7 give plans and profiles for the plant and surrounding area.
Wave runup from the significant wave at the Maine Yankee site was determined in the probable maximum hurricane to be 5.11 feet on the slope south of the turbine building and 6.68 feet on the circulating water pump house. Varying the period of the significant wave affects the extent of wave runup on the structures. As seen on Graph B, on Figure 2.3-8, the wave runup on the slope increases with greater wave period while the wave runup on the screen well increases with shorter wave period.
This condition is due to the wave runup at the screen well being a standing wave while the wave runup on the slope is due to a breaking wave.
The probacility of any wave occurring in a spectrum of waves can be determined using Bretschneider's Joint Distribution as found in Reference 3. Assuming that the design wave occurs during the period of 2.2. hours when the winds in the probable maximum hurricane exceed 110 mph, approximately 1,840 waves can occur. This period of maximum winds we define as the " critical period" of the l probable maximum hurricane. Using Bretschneider's Distribution, the distribution of waves with a height of 5.63 feet and a varying period is shown in Graph A of Figure 2.3-8. This graph shows that j g Rev.14 l 1 G/
DSAR 2-48 l
l
MYAPC A
b 0.6% of the waves that occur when the winds exceed 110 mph have a period of 1.7 to 2.6 seconds; 1
accordingly, the wave runup on the circulating water pump house or slope as plotted in Graph B would have the same frequency of occurrence. Accumulative frequency of wave runup during the " critical period" has been obtained by plotting the sum of the individual frequencies as shown in Graph A versus the corresponding wave runup as shown by Graph B. This accumulative frequency of wave runup is shown in Graph C.
The wave runup frequency curve for the pump house shows that approximately 10% of the waves during the period of maximum winds would result in a wave runup equal to or greater than 6 feet. For reference purposes, design wave runup for both the slope and the pump house is indicated in Graph C. Wave runup equal to or greater than the design runup would occur during approximately 4% of the
" critical period." Should any wave runup occur that would overtop the slope or pump house, the flow rate due to overtopping would be such that the site pump house could drain. It is not considered credible that these waves would be consecutive in the wave spectrum.
Provisions are made in the design of the circulating water pump house to accept the splash and flow of wave runup to Elevation 22 feet 0 inches. This is accomplished with plates which seal the interior deck. For water to overtop the 12-inch kick plate / floodgate system inside the building, water would have to stand above that elevation on the outside of the building; however, this is not possible. Only one door of the pump house will be exposed to the runup. In addition to the precautions designed into the structure, the exposed door can always be sandbagged if runup is a problem. Equipment located in the circulating water pump house and the structure itself have been designed to be unaffected by I
the maximum water height described. Pump seals, castings and auxiliary piping all are installed with due consideration of the maximum water height.
An investigation has been conducted to determine the forces on the outside curtain wall and the supporting floor for the service water. This investigation includes the dynamic forces of a breaking l wave on the structure. The first part of the calculation assumes a wave train approaching the front face of the structure at a 30 degree angle. This angle is considered the flattest angle at which a wave of 5.63 feet could be generated due to the estuarial geometry. We have conservatively assumed the wave break at the structure. The Minikin formula (Reference 3), as modified by the approach angle and wall inclination, was used to calculate the static and dynamic forces on the exterior curtain wall of the structure. The water levelin the interior of the structure was assumed to oscillate with the same period and amplitude as the incident wave. The dynamic force of this free surface rising to stnke the underside of the pump well floor was calculated by determining the momentum change in the vertical direction. The underside of the pump well floor is flat, and thus offers no resistance to horizontal fluid flow, which is the direction to which the velocity is converted once impingement occurs. A factor of two Rev.14 DSAR 2-49
MYAPC U design margins between the strength of the wall and the force of a breaking wave was found.
An investigation has been carried out to examine the characteristics of waves that could be generated across Back River from the east. Significant wave heights of 3.6 feet or less were predicted for conditions of a 2,000 foot fetch length, a sustained wind speed of 110 mph, and 4 different water surface elevations ranging from -7 feet to +15 feet (MSL). The Thijsse and Schijf method (Reference
- 4) formed the basis of these computations. Each of the four wave heights was examined according ;
to wave-breaking criteria summarized in Reference 4 and found to be smaller than a breaking wave.
Consequently, none of" waves generated under these conditions could break. Therefore, they pose no threat to the strucLral integrity of the screen well curtain wall.
The new Fuel Oil Storage Facility is well back from the river bank. Wave run-up on the slope will drain back between waves and not flow around the fuel oil facility's two doors. The doors sills are at Elevation 25 feet,1 inch, which is 5 feet,1 inch, above the highest calculated run-up. One of two vent pipe centerlines penetrates a wall at Elevation 35 feet,7-1/4 inches, while the other vent pipe centerline penetrates a wall at Elevation 35 feet,9 inches. The two fill pipe centerlines, which have locking caps, penetrate a wall at Elevation 21 feet,0 inches. The fill pipe penetrations are grouted and sealed.
All other buildings are even more remote from the river edge and less susceptible to flooding from any (3 cause. Nevertheless, they all are capable of being sandbagged if conditions indicated the need.
G l Computations for these improbable combinations of events show that no structural damage or jeopardy to the plant would result. Even if the waves could break against the pump house structure with appreciably more energy, the curtain wall would not fail catastrophically, but might crack and be held in place by the reinforcing steel. The curtain wall is not required for the integrity of the remainder of the structure.
2.3.3.3 Extreme Low Water in support of original service water system design a study of the most severe combination of tide influencing conditions was made by coupling the effects of a low spring tide and the winds of the probable maximum hurricane blowing from a northerly direction rather than southerly.
The low spring tide level is 5.2 feet below MSL at Lower Hell Gate. Wind setup calculations proceeded from the method summarized in Reference 3. An additional change in the water surface of-2.6 feet was predicted which brings the water surface elevation to -7.8 feet at the service water g3 b DSAR 2-50 Rev.14
r i
,, MYAPC (v) The maximum probable flood flow in the Sheepscot River (Figure 2.3-2) was determined by means of a triangular hydrograph method (Reference. 2). This results in a flow at Wiscasset of 126,500 cfs i (Figure 2.3-3). Due to its vast size, the water levels in the Sheepscot Bay will remain essentially unaffected by this flood flow. Therefore, a backwater curve was calculated for the Sheepscot River from the open coast to Wiscasset, assuming conservatively that none of the flow passes through Back River but that the water surface at the plant site will be the same as Wiscasset.
it was assumed that the highest water levels would occur if the peak of the runoff coincided with the peak of the astronomical high tide and storm surge. Uniform flow was assumed with an n= 0.03, and the area and hydraulic radius at Doggett Castle, as taken from USC&GS Chart No. 314, was used as
! the mean river section. This resulted in a water slope of 0.035 feet per mile, which is equal to a total increase in water levels of only 0.4 feet.
1 2.3.3.2 Wave Runup and Wave Forces Wave runup on the slope above still water level is dependent on the roughness and porosity of the material composing this slope as well as period and height. As given in Reference 3, a sandy slope is considered smooth while a rubble-mound structure or a riprap covered structure is considered rough.
O The slope for which wave runup was determined is covered with trees and brush. Since the trees will break up and retard the waves in the same manner as rubble, the wave runup was determined using a slope roughness equal to the average of smooth and rough as shown in Reference 3. Figures 2.3-4, 2.3-5,2.3-6, and 2.3-7 give plans and profiles for the plant and surrounding area.
Wave runup from the significant wave at the Maine Yankee site was determined in the probable maximum hurricane to be 5.11 feet on the slope south of the turbine building and 6.68 feet on the circulating water pump house. Varying the period of the significant wave affects the extent of wave runup on the structures. As seen on Graph B, on Figure 2.3-8, the wave runup on the slope increases with greater wave period while the wave runup on the screen well increases with shorter wave period.
This condition is due to the wave runup at the screen well being a standing wave while the wave runup on the slope is due to a breaking wave.
l The probability of any wave occurring in a spectrum of waves can be determined using Bretschneider's Joint Distribution as found in Reference 3. Assuming that the design wave occurs during the period of 2.2. hours when the winds in the probable maximum hurricane exceed 110 mph, approximately 1,840 waves can occur. This period of maximum winds we define as the " critical period" of the probable maximum hurricane. Using Bretschneider's Distribution, the distribution of waves with a height of 5.63 feet and a varying period is shown in Graph A of Figure 2.3-8. This graph shows that Rev.14
, o DSAR 2-48 i
l l
,a O 0.6% of the waves that occur when the winds exceed 110 mph have a period of 1.7 to 2.6 seconds; accordingly, the wave runup on the circulating water pump house or slope as plotted in Graph B would have the same frequency of occurrence. Accumulative frequency of wave runup during the " critical period" has been obtained by plotting the sum of the individual frequencies as shown in Graph A versus the corresponding wave runup as shown by Graph B. This accumulative frequency of wave runup is shown in Graph C.
The wave runup frequency curve for the pump house shows that approximately 10% of the waves during the period of maximum winds would result in a wave runup equal to or greater than 6 feet. For reference purposes, design wave runup for both the slope and the pump house is indicated in Graph C. Wave runup equal to or greater than the design runup would occur during approximately 4% of the
" critical period." Should any wave runup occur that would overtop the slope or pump house, the flow rate due to overtopping would be such that the site pump house could drain. It is not considered credible that these waves would be consecutive in the wave spectrum.
. Provisions are made in the design of the circulating water pump house to accept the splash and flow of wave runup to Elevation 22 feet 0 inches. This is accomplished with plates which seal the interior deck. For water to overtop the 12-inch kick plate / floodgate system inside the building, water would
, have to stand above that elevation on the outside of the building; however, this is not possible. Only one door of the pump house will be exposed to the runup. In addition to the precautions designed into the structure, the exposed door can always be sandbagged if runup is a problem. Equipment located in the circulating water pump house and the structure itself have been designed to be unaffected by the maximum water height described. Pump seals, castings and auxiliary piping all are installed with due consideration of the maximum water height.
An investigation has been conducted to determine the forces on the outside curtain wall and the supporting floor for the service water. This investigation includes the dynamic forces of a breaking wave on the structure. The first part of the calculation assumes a wave train approaching the front face of the structure at a 30 degree angle. This angle is considered the flattest angle at which a wave of 5.63 feet could be generated due to the estuarial geometry. We have conservatively assumed the wave break at the structure. The Minikin formula (Reference 3), as modified by the approach angle and wall inclination, was used to calculate the static and dynamic forces on the exterior curtain wall of the structure. The water level in the interior of the structure was assumed to oscillate with the same period and amplitude as the incident wave. The dynamic force of this free surface rising to strike the underside of the pump well floor was calculated by determining the momentum change in the vertical J direction. The underside of the pump well floor is flat, and thus offers no resistance to horizontal fluid flow, which is the direction to which the velocity is converted once impingement occurs. A factor of two p Rev.14 l
DSAR 2-49 6 I
l i
' design margins between the strength of the wail and the force _of a breaking wave was found.
An investigation has been carried out to examine the characteristics of waves that could be generated
.across Back River from the east. Significant wave heights of 3.6 feet or less were predicted for conditions of a 2,000 foot fetch length, a sustained wind speed of 110 mph, and 4 different water surface elevations ranging from -7 feet to +15 feet (MSL). The Thijsse and Schijf method (Reference
- 4) formed the basis of these computations. Each of the four wave heights was examined according to wave-breaking criteria summarized in' Reference 4 and found to be smaller than a breaking wave.
Consequently, none of the waves generated under these conditions could break. Therefore, they pose no threat to the structural integrity of the screen well curtain wall.
The new Fuel Oil Storage Facility is well back from the river bank. Wave run-up on the slope will drain back between waves and not flow around the fuel oil facility's two doors. The doors sills are at Elevation 25 feet,1 inch, which is 5 feet,1 inch, above the highest calculated run-up. One of two vent pipe centerlines penetrates a wall at Elevation 35 feet,7-1/4 inches, while the other vent pipe centerline penetrates a wall at Elevation 35 feet,9 inches. The two fill pipe centeriines, which have locking caps,
. penetrate a wall at Elevation 21 feet,0 inches. The fill pipe penetrations are grouted and sealed.
All other buildings are even more remote from the river edge and less susceptible to flooding from any cause. Nevertheless, they all are capable of being sandbagged if conditions indicated the need.
Computations for these improbable combinations of events show that no structural damage orjeopardy to the plant would result. Even if the waves could break against the pump house structure with appreciably more energy, the curtain wall would not fail catastrophically, but might crack and be held in place by the reinforcing steel. The curtain wall is not required for the integrity of the remainder of the structure.
2.3.3.3 Extreme Low Water 1
i in support of original service water system design a study of the most severe combination of tide influencing conditions was made by coupling the effects of a low spring tide and the winds of the probable maximum hurricane blowing from a northerly direction rather than southerly.
The low spring tide level is 5.2 feet below MSL at Lower Hell Gate. Wind setup calculations proceeded from the method summarized in Reference 3 An additional change in the water surface of -2.6 feet was predicted which brings the water surface elevation to -7.8 feet at the service water A '
V DSAR' 2-50 Rev.14 s
I l
l MYAPC
')
- The maximum probable flood flow in the Sheepscot River (Figure 2.3-2) was determined by means of l a triangular hydrograph method (Reference. 2). This results in a flow at Wiscasset of 126,500 cfs (Figure 2.3-3). Due to its vast size, the water levels in the Sheepscot Bay will remain essentially unaffected by this flood flow. Therefore, a backwater curve was calculated for the Sheepscot River from the open coast to Wiscasset, assuming conservatively that none of the flow passes through Back River but that the water surface at the plant site will ba the same as Wiscasset.
I It was assumed that the highest water levels would occur if the peak of the runoff coincided with the l l peak of the astronomical high tide and storm surge. Uniform flow was assumed with an n= 0.03, and the area and hydraulic radius at Doggett Castle, as taken from USC&GS Chart No. 314, was used as i the mean river section. This resulted in a water slope of 0.035 feet per mile, which is equal to a total increase in water levels of only 0.4 feet.
2.3.3.2 Wave Runup and Wave Forces i
Wave runup on the slope above still water levelis dependent on the roughness and porosity of the material composing this slope as well as period and height. As given in Reference 3, a sandy slope is considered smooth while a rubble-mound structure or a riprap covered structure is considered rough.
Q The slope for which wave runup was determined is covered with trees and brush. Since the trees will break up and retard the waves in the same manner as rubble, the wave runup was determined using a slope roughness equal to the average of smooth and rough as shown in Reference 3. Figures 2.3-4, 2.3-5,2.3-6, and 2.3-7 give plans and profiles for the plant and surrounding area.
Wave runup from the significant wave at the Maine Yankee site was determined in the probable maximum humcane to be 5.11 feet on the slope south of the turbine building and 6.68 feet on the circulating water pump house. Varying the period of the significant wave affects the extent of wave runup on the structures. As seen on Graph B, on Figure 2.3-8, the wave runup on the slope increases with greater wave period while the wave runup on the screen well increases with shorter wave period.
This condition is due to the wave runup at the screen well being a standing wave while the wave runup on the slope is due to a breaking wave.
The probability of any wave occurring in a spectrum of waves can be determined using Bretschneider's Joint Distribution as found in Reference 3. Assuming that the design wave occurs during the period of 2.2. hours when the winds in the probable maximum hurricane exceed 110 mph, approximately 1,840 waves can occur. This period of maximum winds we define as the " critical period" of the probable maximum hurricane. Using Bretschneider's Distribution, the distribution of waves with a height of 5.63 feet and a varying period is shown in Graph A of Figure 2.3-8. This graph shows that p Rev.14 b
DSAR 2-48
MYAPC n
0.6% of the waves that occur when the winds exceed 110 mph have a period of 1.7 to 2.6 seconds; accordingly, the wave runup on the circulating water pump house or slope as plotted in Graph B would have the same frequency of occurrence. Accumulative frequency of wave runup during the " critical period" has been obtained by plotting the sum of the individual frequencies as shown in Graph A versus the corresponding wave runup as shown by Graph B. This accumulative frequency of wave runup is shown in Graph C.
The wave runup frequency curve for the pump house shows that approximately 10% of the waves during the period of maximum winds would result in a wave runup equal to or greater than G foet. For reference purposes, design wave runup for both the slope and the pump house is indicated in Graph C. Wave runup equal to or greater than the design runup would occur during approximately 4% of the
" critical period." Should any wave runup occur that would overtop the slope or pump house, the flow rate due to overtopping would be such that the site pump house could drain. It is not considered credible that these waves would be consecutive in the wave spectrum.
Provisions are made in the design of the circulating water pump house to accept the splash and flow of wave runup to Elevation 22 feet 0 inches. This is accomplished with plates which seal the interior deck. For water to overtop the 12-inch kick plate / floodgate system inside the building, water would have to stand above that elevation on the outside of the building; however, this is not possible. Only one door of the pump house will be exposed to the runup. In addition to the precautions designed into the structure, the exposed door can always be sandbagged if runup is a problem. Equipment located in the circulating water pump house and the structure itself have been designed to be unaffected by the maximum water height described. Pump seals, castings and auxiliary piping all are installed with due consideration of the maximum water height.
An investigation has been conducted to determine the forces on the outside curtain wall and the supporting floor for the service water. This investigation includes the dynamic forces of a breaking wave on the structure. The first part of the calculation assumes a wave train approaching the front face of the structure at a 30 degree angle. This angle is considered the flattest angle at which a wave of 5.63 feet could be generated due to the estuarial geometry. We have conservatively assumed the wave break at the structure. The Minikin formula (Reference 3), as modified by the appro9ch angle and wall inclination, was used to calculate the static and dynamic forces on the exterior curtain wall of the structure. The water level in the interior of the structure was assumed to oscillate with the same I
period and amplitude as the incident wave. The dynamic force of this free surface rising to strike the underside of the pump well floor was calculated by determining the momentum change in the vertical direction. The underside of the pump well floor is flat, and thus offers no resistance to horizontal fluid flow, which is the direction to which the velocity is converted once impingement occurs. A factor of two Rev.14 DSAR 2-49 I
MYAPC V design margins between the strength of the wall and the force of a breaking wave was found.
An investigation has been carried out to examine the characteristics of waves that could be generated across Back River from the east. Significant wave heights of 3.6 feet or less were predicted for conditions of a 2,000 foot fetch le'ngth, a sustained wind speed of 110 mph, and 4 different water surface elevations ranging from -7 feet to +15 feet (MSL). The Thijsse and Schijf method (Reference
- 4) formed the basis of these computations. Each of the four wave heights was examined according to wave-breaking criteria summarized in Reference 4 and found to be smaller than a breaking wave.
Consequently, none of the waves generated under these conditions could break. Therefore, they pose no threat to the structural integrity of the screen well curtain wall. l I
The new Fuel Oil Storage Facility is well back from the river bank. Wave run-up on the slope will drain back between waves and not flow around the fuel oil facility's two doors. The doors sills are at Elevation 25 feet,1 inch, which is 5 feet,1 inch, above the highest calculated run-up. One of two vent l pipe centerlines penetrates a wall at Elevation 35 feet,7-1/4 inches, while the other vent pipe centerline penetrates a wall at Elevation 35 feet,9 inches. The two fill pipe centerlines, which have locking caps, penetrate a wall at Elevation 21 feet,0 inches. The fill pipe penetrations are grouted and sealed. )
l All other buildings are even more remote from the river edge and less susceptible to flooding from any cause. Nevertheless, they all are capable of being sandbagged if conditions indicated the need.
(~N]
L l Computations for these improbable combinations of events show that no structural damage or jeopardy to the plant would result. Even if the waves could break against the pump house structure with appreciably more energy, the curtain wall would not fait catastrophically, but might crack and be held in place by the reinforcing steel. The curtain wall is not required for the integrity of the remainder of the structure.
2.3.3.3 Extreme Low Water in support of original service water system design a study of the most severe combination of tide influencing conditions was made by coupling the e'fects of a low spring tide and the winds of the probable maximum hurricane blowing from a northerly direction rather than southerly.
The low spring tide level is 5.2 feet below MSL at Lower Hell Gate. Wind setup calculations proceeded from the method summarized in Reference 3. An additional change in the water surface of -2.6 feet was predicted which brings the water surface elevation to -7.8 feet at the service water n
DSAR 2-50 Rev.14