ML20011D736
| ML20011D736 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 07/01/1989 |
| From: | CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | |
| Shared Package | |
| ML20011D723 | List: |
| References | |
| NUDOCS 8912280339 | |
| Download: ML20011D736 (61) | |
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3(d TABLE OF CONTENTS Chapter 2 2.I GEOGRAPHY AND DEMOGRAPHY 2.1.1 SITE LOCATION AND DESCRIPTION r
2.1.2 EXCLUSION AREA AUTHORITY AND CONTROL 2.1.3 POPULATION DISTRIBUTION 2.2 NEARBY INDUSTRIAL, TRANSPORTATION, AND MILITARY FACILITIES 2.2.1 LOCATIONS AND ROUTES 2.2.2 EVALUATION
SUMMARY
2.3 METEOROLOGY 2.3.I NORMAL AND SEVERE WEATHER l
2.3.2 METEOROLOGICAL MONITORING L
2.3.3 ATMOSPHERIC TRANSPORT AND DIFFUSION ESTIMATES 2.4 HYDROLOGY 2.4.1 HYDROLOGIC DESCRIPTION 1
2.4.2 FLOODS 2.4.3 PROBABLE MAXIMUM FLOODING (PNF) 2.4.4 PROBABLE MAXIMUM PRECIPITATION (PHP) 2.4.5 LOSS OF ULTIMATE HEAT SINK (UHS) 2.4.6 FLOOD EMERGENCY OPERATIONAL REQUIREMENTS 2.5 GEOLOGY, SEISMOLOGY AND GEOTECHNICAL ENGINEERING 2.5.1 BASIC GEOLOGIC AND SEISMIC INFORMATION 1
2.5.2 VIBRATORY GROUND HOTION t
2.5.3 SURFACE FAULTING 2.5.4 STABILITY OF SUBSURFACE MATERIALS AND FOUNDATIONS 2.5.5 STABILITY OF SLOPES RJ 2.5.6 EMBANKMENTS AND DAMS MIO687-0254A-BX01 8912280339 891222 I
PDR ADOCK 05000155 K
CHAPTER 2 SITE CHARACTERISTICS 2.1 GEOGRAPHY AND DEMOGRAPHY 2.1.1 SITE LOCATION AND DESCRIPTION The Big Rock Point nuclear plant site plan for the facility is shown in Drawing 0740020003.
The site property consists of gently sloping wooded and cleared land at the western extremity of the southern shore of Little Traverse Bay. The site is 228 miles NNW of Detroit and 262 miles NNE of Chicago.
Figure 2.1 shows the location of the site with respect to the over-all view of the state of Michigan and its surr>undings.
Fi_gure 2.2, Site Map, indicates the property owned by Consumers Power Company, in relation to the nearby highway and railroad. Figure 2.2 also indicates the location of the reactor on the site.
2.1.1.1 Immediate Environs The immediate environs of the site are sparsely occupied and little utilized. The gently sloping, partly wooded land with no significant topographic features found on the site itself, continues for several miles. To the south, at a distance of about three miles, is Lake Charlevoix, an inland extension of Lake Michigan of significant size.
The size and shape of the site and the location of the reactor enclosure on it insure that no residences or commercial facilities are within one-half mile of the reactor. Only scattered rural or resort residences and a few commercial facilities are found within several miles of the site.
Commercial sad cultural facilities and important residential areas are found in Charlevoix, about four miles southwest of the site; and at Petoskey, about eleven miles east of the site. Outside of such cities, there are no nearby significant industrial operations, except for a cement plant about six miles to the west.
2.1.1.2 Site Access Access to the site is available by U.S. Michigan Route #31 which passes the site at a distance of one-half to one mile from the reactor location and connect the cities of Charlevoix and Petoskey.
Access to the plant is by a winding access road running west from U.S. 31.
2.1-1 MIO687-0254A-BX01
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2.1.1.3 Plant Features The Big Rock Point nuclear power plant consists of a direct cycle, forced circulation boiling water reactor, a power extraction system, l
and associated service facilities. The principal structures include:
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A 130-ft diameter spherical containment vessel Reactor Building (T-1) l A Turbine Generator Building (B-3)
A structure housing water intake facilities and diesel generator Screen, Well and Pump House (B-4)
Emergency Generator Room (B-5)
A 240 foot stack (chimney) (B-1)
A Alternate Shutdown Panel Building (ASPB)(B-24)
A Security Building (B-16)
Waste Storage Vaults (Liquid)(B-11) (Solid)(B-10)
Reference BRP Drawing 0740G20003 Site Plan for the Building and Structure locations and to Figure 2.3 for general Plant Facility Identifications.
The containment vessel houses the reactor, recirculation piping, pumps, steam drum, fuel pool, and equipment for removal of shutdown heat. The turbine-generator and other conventional plant components are housed in a separate adjoining building.
2.1.1.4 Surrounding Area Charlevoix County, with a land area of about 400 squart miles, has farm earnings (Reference 3) of about $1 - 1/2 million per year, with about. 18% of its land area in agricultural ~use.
Produce is principally forest, dairy and poultry products, and fruit. Statistics on the economy of the three counties around the site (the approximate thirty-mile radius), are shown in the following table.
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TABLE 2.1 STATISTICS OF SURROUNDING AREA (Reference 3) i County Antrim Charlevoix Emmet j
Land Area, sq mile 480 421 468 Population 1980 16,194 19,907 22,992 Population /sq mile 33.7 47.3 49.1
% of Population Increase 1960-1970 21.6%
23.2%
15.3%
% of Population Increase 1970-1980 28.4%
20.3%
25.4%
% of Urban Population 1980 26.5%
33.4%
26.5%
Persons / Household 1980 2.80 2.80 2.76 Total Number of Households 4506 5371 5923 Manufacturing Establishments,1977 51 52 41
% With Over 20 Employees 21.6%
34.6%
29.3%
Average Annual Manufacturing l
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Employment 1977 1600 2100 1300 Farns, '978 268 247 230 Average Size Farms, Acres 238 175 135 Value of Farm Products Sold, (in $1,000's) 11,100 4,400 3,400 Including % of Crops
- Note 1 60.6%
- Note 2
- Note 2
% of Livestock Products 31.9%
57.8%
66.6%
- Note 1 - Includes Forest Products
- Note 2 - Figures were withheld
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Typical of most. of the northern portion of the southern peninsula of Michigan, and because of comparatively moderate summer climate and
'j abundant lake frontage, the general region of the site is an important summer vacationland, llowever, this summer occupancy is not a significant factor within about two miles of tTse plant site.
2.1.2 EXCLUSION AREA AUTl10RITY AND CONTROL (Reference 1) i The Big Rock Point nuclear power plant is located on the shore of
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Lake Michigan in Charlevoix County in the northern part. of Michigan's lower peninsula. The plant site is approximately three and one half miles northeast of the city of Charlevoix and eleven miles west of the city of Petoskey, Michigan. The site exclusion area is defined by the site property limits and thus the exclusion area boundary lines are identical to the plant property lines shown on the Site Map. The nearest boundary of the exclusion area on the landward side of the plant is 2,680 feet.
The approximately 600 arres of property within the exclusion area boundaries including the mineral rights is owned by the licensee.
Parts of the exclusion area are traversed by U.S. Route 31 and the' Chesapeake and Ohio Railroad, portions of which are owned by the Michigan Department of Transportation as shown in Figure 2.2.
Arrangements have been made to control traffic on Route 31 in the event of a plant emergency, as documented in the Site Emergency Plan (Reference 2).
Similar arrangements, however, have not been made regarding the railroad line as the access from the west has been rendered impossible by removal of the Pine River Rail trestle and access from the east is currently impossible due to washout of the tracks near Petoskey. Further, abandonment proceedings are in progress for this section of tracks.-
The Plant under Michigan law, owns to tha water's edge and has the i
right to control access from the landward side to the lakeshore-frontage within the exclusion area.
The exclusion area is not defined over the waters of Lake Michigan adjacent to-the site. While Big Rock Point has not specifically defined an exclusion area over the water, arrangements have been made with the U.S. Coast Guard, as documented in the Site Emergency Plan (Reference 2), for the control of water traffic offshore of the plant in the event of an emergency.
Evaluation Summary The topic of Exclusion Area Authority and Control was evaluated by the NRC as part of the Systemic Evaluation Program topic number II-1.A.
This review resulted in an assessment and evaluation (Reference 1) which found that the arrangements with the U.S. Coast Guard meet the intent of t.he criteria in Part 100 and, therefore, the lack of a defined exclusion area over the water does not constitute a significant safety issue for the SEP review.
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d This evaluation concluded that Big Rock Point has the proper authority, with one exception, to determine all activities withir. the exclusion area, as required by 10 CFR Part 100 - The exception concerned the lack of an arrangement to control traffic on _the Chesapeake and Ohio e
hailroad line which traverses a part of the exclusion area. This was a departure from current criteria but was not considered a significant safety issue in view of the location of the railroad li.e in relation t
to the plant, the then low volume of traffic on the line, and the stated intention of the licensee to include ~ such w arrangement (*
Note 1) in the new site emergency plan.
This completed the evaluation of the SEP topic.
- Note 1 Since_that evaluation was completed, the need to include _this arracrement in the Site Emergency Plan has become moot as described in this report.
If in the future the railroad line is reopened, arrangements for control of traffic on the line in the event of a plant emergency will be included in the Site Emergency Plan.-
2,1.3 POPULATION DISTRIBUTION The site is remote from any large metropolitan areas, and has generally favorable low surrounding permanent population as shown in Figure 2.4 which wt.s extracted from Reference 4.
2.1.3.1 Population Within Five (5) Miles A survey of tne population within a five mile radius of the plant indicates the following ring population (Reference 4) as of November 1983:
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TABLE 2.2 Special Ring Permanent Seasonal Transient Facility Total Mile Residents Residents
- Note 1
- Note 2 Population 0-1 0
0 355 0
355 1-2 133 0
7 6
146 2-3 789 562 320 58 1729 3-4 1546 658 666 584 3454 4-5 2765-405 1196 1,114 5480 Total Cumulative'11,164
- Note 1 - Persons in work force, Hotel / Mote 1' Guests and Visitors to Recreation Area.
- Note 2 - School, Medical, Nursing Home, and Incarceration Facilities.
The preponderance of population toward the, southwest coincides with a minimum wind direction probability in that_ direction.
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2.1.3.2 Population Within Thirty (30) Miles 1
The region surrounding the Big Rock Point plant is generally of low population density and rural to suburban in character. The total population within the counties of Charlevoix, Emmet, and Antrim, which cover the majority of the area within 30 miles of the plant, based on 1980 census data, was about 59,000, this region has experienced an overall average increase-of 25% in their resident population between 1970 and 1980 (Refer to Table 2.1).
The majority of this population increase is attributed to in-migration primarily from other regions of Michigan.
2.1.3.3 Seasonal Population Seasonal population is an important factor in the area surrounding the plant as this part of Michigan attracts a large number of visitors year round with the peak occurring in the summer season. The seasonal population (ie, seasonal residents, overnight tourists, and daily-visitors) in the three county area is estimated to increase the population by 75% during the height of the season (Reference 6).
2.1.3.4 Low Population Zone and Emergency Planning Zones The low population zone specified for Big Rock Point site is the area within two and one half (2.5) mile radius of the Plant; the primary fs
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emergency planning zone is the five (5) mile radius; and the secondary emergency planning zone extends to a thirty (30) mile radius _(Reference 2).
2.1.3.5 Population Centers TABLE 2.3 Principal urban areas within 60 miles are:
- Population Distance Direction Urban Center 1960 1970 1980 from Site from Site Charlevoix 2,751 3,519 3,296 4 Miles.
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Harbor Springs 1,433 1,662 1,567 11 Miles ENE Petoskey 6,138 6,342 6,097 11 Miles E.
Boyne City 2,797 2,969 3',348 14 Miles SE East Jordan 1,919 2,041 2,185 14 Miles SSE Gaylord 2,569 3,012-3,011 33 Miles SE-Cheboygan 5,859 5,553 5,106 40 Miles' NE St. Ignace 3,334 2,892 2,632 42 Miles NNE
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Traverse City 18,432 18,048 15,516 45 Miles SSW Grayling
'2,015 2,143 1,792 52 Miles SSE L
- Population figures are 1980 census (Reference 5) iO lv l
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Charlevoix is the closest urban center and does not presently nor foreseeably fall within the population center definition of 10 CFR Part 100.
2.1.3.6 Population Density i
By applying the Seasonal Population increase to the three county 1980 Census Resident Population, the cumulative population of the majority of the area within thirty (30) miles of the plant is about 103,000 i
people for a population density of about seventy five (75) persons per square mile. This Population Density is not expected to approach the 10 CFR Part 100 Guideline Limits during the' Plant Lifetime.
2.1.3.7 Evaluation Summary The topic of Population Distribution was evaluated by the NRC as part of the Systematic Evaluation Program topic number II-1.B.
This review resulted in an assessment and evaluation (Reference 1) which.
found that based upon an examination of present and projected population data and on observations made'during a visit to the site in July 1979, that neither Charlevoix nor any other city within 30 miles' of the plant is now, or is likely to become in the foreseeable' future, a population center, (more than 25,000 residents), as defined in 10 CFR Part 100. Further, the NRC concluded that the low population-fx zone and population center distances specified for the Big Rock Point
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site remain valid and the site is in conformance with the distance requirements of 10 CFR Part 100 in that the population center distance is more than one and one-third times the distance from the reactor to the outer boundary of the low population zone.
This completed the evaluation of this SEP topic. Since the plant.
site conforms to current licensing criteria, no additional SEP review is required.
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FIGURE 2.4 1980 PERMANENT POPULATION WITHIN THE BIG ROCK POINT PLUME EXPOSURE EPZ i-ENE M
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k 2.2 NEARBY INDUSTRIAL, TRANSPORTATION, AND MILITARY FACILITIES r
2.2.1 LOCATIONS AND ROUTES s
Figure 2.5 Provides a listing of manufacturing plants in the five (5) mile radius of the Big Rock Point Plant.
Figure 2.6 Provides additional listings for the City of Charlevoix which falls within the southwest quadrant from the Big Rock Point Plant.
These Figures were extracted from Appendix "A" of Reference 4.
Industrial activity in the vicinity of the Big Rock Point Plant consists primarily of small manufacturing companies. There are two cement plants and quarries in the area, one operating plant about six miles to the south-southwest and one plant which has discontinued mining operation about nine miles to the east from the Big Rock Point Plant.
A low 1cvel military training route (VR-1634) currently passes 5.2 miles from the Big Rock Point Plant at its closest point. A former t
military low level training route (IR 600/601) a simulated radar bomb scoring range over Lake Michigan'has been discontinued.
2.2.2 EVALUATION
SUMMARY
The topic of Potential Hazards Due to Nearby Industrial, Transportation and Military Facilities was evaluated by the NRC as part of the Systematic Evaluation Program topic number II-1.C.
This resulted in a safety evaluation (Reference 7) as follows:
2.2.2.1 Industrial Activity Industrial activity in the vicinity of the Big Rock Point Plant consists primarily of small manufacturing companies. There are also some cement plants and quarries in tha area. The closest industrial facility is a manufacturing plant located about one mile east where 105 employees are engaged in producing custom molded plastic fixtures.
An inventory of approximately 100,000 pounds of thermoplastic materials is stored at the facility.
These materials are not an explosive hazard but could produce toxic combustion-products if a fire should occur. The severity of this event with regard to safe operation of the nuclear plant, in particular, the habitability of the control room, would depend on many factors including source parameters, wind speed and direction, cloud plume rise, and protective actions taken by plant operators.
(Control room habitability is addressed in Chapter 6 of this updated FHSR).
An industrial park is located about 2.5 miles southwest of the plant.
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Several light manufacturing companies employing a total of about 200 b
persons are located in the park. No hazardous materials in quantities 2.2-1 MIO987-0359A-BX01
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b large enough to affect the safe operation of the nuclear plant are j
known to be processed, stored, or transported at the industrial park.
An oil conpany storage terminal is located on US Route 31 near the industrial park.
The maximum storage capacity at the terminal is approximately 46,000 gallons of fuel oil and 40,000 gallons of gasoline. No propane is stored at the facility. The separation distance between the fuel storage terminal and the nuclear plant (over two miles) is considered adequate to preclude accidents at the terminal affecting the safe operation of the nuclear plant. A local l
planning official has stated that no additional industrial developments-are proposed or planned for the area in the vicinity of the plant.
2.2.2.2 Transportation Activity The nearest highway to the plant is US Route 31 (Refer to Figure 2.2) which is located 2,760 feet southeast at its closest point of approach.
Shipments of explosives used in local quarry operations travel on Route 31 past the plant. The guidance of Regulatory Guide 1.91, Revision 1 was utilized to evaluate the consequences of a postulated explosive accident on the highway.
We find that the separation distance between the highway and the plant exceeds the minimum distance criteria given in the regulatory guide for truck-size shipments of explosive materials and, therefore, there is reasonable assurance that an explosive accident on the O
highway will not affect the safe operation of the plant.
We have also evaluated the potential consequences of highway accidents involving toxic chemicals. A conservative analysis indicates that certain toxic chemicals which form a gas cloud when released (eg, chlorine, ammonia) could reach the plant in concentrations high enough to be of concern depending on such factors as spill size and atmospheric dispersion conditions. Accident data compiled by the Michigan Department of Highways indicate that the-expected frequency-of an accident involving hazardous chemicals on the approximately ten-mile stretch of US Route 31 past the plant is about 1.3 x 10 a per year. The percent of tanker truck accidents which involve a significant loss of material is about 2%. The percent of time on an annual basis that the wind blows from the ten-mile stretch of Route 31 toward the plant is about 51%. Thus, we conservatively estimate that the potential annual exposure rate to,the plant due to toxic chemical accidents on Route 31 is about 10 5 per year.
The probability of toxic chemical exposure noted above is higher than the acceptance probability level used in' current licensing criteria (see SRP 2.2.3).
However, the calculated frequency of toxic chemical accidents on Route 31 past the plant is based on the assumption that the toxic chemical traffic on Route 31 is similar to that on other highways in Michigan. Our review of the industrial activity in the i
region surrounding the plant indicates a lack of industrial or O
chemical complexes which would generate toxic chemical traffic.
V Therefore, it is our judgement that the threat to the safe operation 2.2-2 MIO987-0359A-BX01
of the plant posed by highway accidents involving toxic chemicals is sufficiently remote so that such accidents need not be considered as a design basis event.
A Chesapeake & Ohio Railroad branch line runs approximately 5,600 feet south of the plant at its closest point.
Information obtained from the railroad company indicates that three freight trains per week providing only local service use the line. The railroad company identifies propane as the only hazardous material shipped on the line. We have evaluated the consequences of a postulated explosion on the railroad in accordance with the guidance in Regulatory Guide 1.91, Revision 1.
We find that the separation distance between the railroad line and the plant exceeds the minimum distance criteria given in the regulatory guide for railroad shipments of explosive materials and, therefore, is acceptable.
(Note: As explained in Section 2.1.2 of this Updated FHSR, this line is currently not in-use.)
2.2.2.3 Pipelines The nearest pipeline to the plant-is a 6 inch diameter natural gas line which is located about 1.5 miles south. At this distance, pipeline accidents will not affect the safe operation of the plant, based on evaluations of pipeline accidents done in previous licensing reviews. There are no gas or oil production fields, underground storage facilities, or refineries in the vicinity of the plant.
2.2.2.4 Waterways i
There are no large commercial harbors near the plant but some commercial shipping does take place at Charlevoix Harbor which is-approximately four miles southwest of the plant.. While the great majority of the cargo consists of non-hazardous commodities such as i
coal and limestone, some gasoline and fuel oil is shipped from the harbor by barge. All of the gasoline-and fuel oil is_ loaded into barges from trucks for shipment to Beaver Island which is some 25 miles northwest of Charlevoix. Two barge line companies, each with one barge, are engaged in this trade. Between_them they make about 20 trips per year and the captains estimate that they come.no closer than about three to four miles from the plant. Thus, the occurrence of a barge accident with consequences severe enough to affect the safe operation of the plant is extremely unlikely' and does not constitute a credible risk to the plant. Similarly, the main shipping route in Lake Michigan which is located about 40 miles northwest of the plant is not a threat to plant operation..
2.2.2.5 Airports i
The nearest airport to the plant is Charlevoix Municipal ~ Airport which is located approximately five miles southwest. The airport has one paved runway 3,500 feet in length oriented in an east-west direction and two turf runways.
Charlevoix Municipal is a general 2.2-3 MIO987-0359A-BX01
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aviation facility used primarily by light single engine ' aircraft.
There were a total of 16,800 itinerant and local operations at the I
field in 1976 and this is projected to increase to 71,000 operations in 1997 according to the airport master plan. The master plan l
recommends that Charlevoix Municipal Airport should be upgraded to a l
basic transport facility, ie, one capable of handling turbojet powered aircraft up to 60,000 pounds gross weight. Using the analytical model given in SRP 3.5.1.6, we conservatively calculate the probability of an aircraft from Charlevoix Airport crashing into the Big Rock Point Plant is 8.5 x 10 7 per year.
Conservatisms in our calculation include the use of the projected 1997 level of operations, the assumption that all aircraft arriving or departing the airport fly over the plant area, and the consideration of the entire plant as a potential " target area".
In fact, since the vast majority of aircraft operating at Charlevoix Airport are expected to b: light, general' aviation aircraft, only a small fraction of postul.ted aircraft strikes would seriously affect the safety of the plant.
The probability of an accident resulting in severe radiological consequences would,,
therefore, be even lower than the probability value given above. We conclude that the Charlevoix Airport 'does not represent an undue risk to the safe operation of the nuclear plant.
2.2.2.6 Military Training Routes (Reference 8)
A military low level training route (VR-1634) passes 5.2 miles from the Big Rock Point Plant at its closest point.
In the Big Rock Point Spent Fuel Pool Expansion Hearings, the Atomic Safety and Licensing Board (ASLB) concluded ".'..that the evidence has demonstrated that the risk from aircraft to the Big Rock Point Plant is sufficiently low so that it need not be considered further in the design of the plant...."
2.2.3 SAFETY EVALUATION CONCLUSIONS (Reference 7)
We conclude that.the Big Rock Point Plant is adequately protected and L
can be operated with an acceptable degree of safety with regard to industrial, transportation, and military activities in the vicinity of the plant.
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Note:
Further support for the NRC Staffs conclusions pertaining to military, general aviation, and Charlevoix airport cumulative realistic probability.'of an aircraft crashing into. the plant can be found in Reference 8 and was about 2 x 10 a per year i
in 1984 and has since been further reduced by the closing of military training route (IR-600/601).
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2.3 METEOROLOGY A " Meteorology Study of Natural Ventilation in the Atmosphere,' Big Rock Point Nuclear Plant, Charlevoix, Michigan," Final Report was.
issued in Cacember 1963 by the University of Michigan. This Report is contained in Volume Two of the original FHSR. This study includes collection and analyses of wind data - eg, speed, direction, and turbulence, variability of these parameters with height,. temperature lapse rates, and diffusion studies to determine the local effects of.
the-lakeside location on air passing the site and was designed to furnish that information-which would be needed to accurately assess the general air flow and dilution potential of the air passing the plant site.
A 256 foot tower was built on the site to support the study and was instrumented to provide measurements of air temperature at six different levels and wind data at four different levels.
In addition, the lake water temperature was measured.
The report described the tower installation and summarized the wind data collected from February 1961 through January 1963, and provided typical annual variation of the mean water temperature at a depth of three feet in Little Traverse Bay and the mean daily maximum air temperature at a height of ten feet based on two years of data.
7-g The general meteorological data available from the surrounding areas (j
and the data collected during the two year study indicate that.there are no factors which would produce significant limitations on plant operations. Specifically, the high average wind speed coupled with the relatively low percentages of calm conditions at the 256 foot level during most of the year indicate advantageous diffusion conditions would be prevalent a great deal of the time.
1 To further substantiate that advantageous diffusion conditions would.
exist much of the time, diffusion studies were initiated during the summer of 1961. These studies. utilized the photography of smoke plumes released from the tower in an effort to obtain moderately accurate measurements of diffusion under the most adverse meteoro-
. logical conditions. The smoke studies were intended to define the lower limits of diffusion capability at the site.
The " Smoke Plume Photography Study, Big Rock Point Nuclear Plant, Charlevoix,-Michigan," Progress Report No. 3, was issued in December 1963 by the University of Michigan. This report is contained in Volume Two of the. original FHSR.
Based upon the results of the two phase meteorological study made at.
the site, the annual average licensed stack discharge rate at one curie /second was the highest licensed rate for any reactor operating in 1964.
7O 2.3-1
'MIO987-0360A-BX01
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The 256 foot tower was subsequently removed and present meteorological monitoring is described in Section 2.3.2 below and in the Big Rock j
Point Site Emergency Plan.
Indications are that the normal meteorology of the site region will produce no significant limitations on plant design and operation.
Generally prevailing winds are from the western half of the compass and there are no significant population centers, as defined in 10 CFR Part 100, within the 30 mile radius of the plant.
4 2.3.1 NORMAL AND SEVERE WEATHER The topic of Severe Weather Phenomena was evaluated by the NRC as part of the Systematic Evaluation Program; this review resulted in a-staff safety evaluation (SE) which assumed a licensing basis (Reference 9) for the following conditions.
Consumers Power Company reviewed the SE and the values selected by the NRC for extreme temperature, lightning strikes, snow and ice loads, and wind and tornado loadings have been verified: against climatological data selected to be representative of site conditions.
All parameters except the wind and tornado loading were verified' against the climatological data recorded for the Pellston FAA weather station. Climatological data recorded for the Muskegon National Weather Service station were used to verify the wind loading value.
., "o Current guidelines for estimating tornado and extreme wind character-istics were used to verify the tornado loading values. The'results of the review are documented in Reference 10 and the CPCo conclusions follow each of the conditions from the NRC Safety Evaluation assumptions.
2.3.1.1 Temperature (NRC-SE)
Normal daily temperatures range from a minimum of ten degrees Fahrenheit in January to a maximum of 80 degrees Fahrenheit in July. Measured extreme temperatures for the site region are 103 degrees Fahrenheit l
and -37 degrees Fahrenheit. The extreme maximum and minimum temperatures appropriate at the Big P.ock Point site for general plant design (ie, HVAC systems) are 86 degrees Fahrenheit (equalled or exceeded 1% of the time) and -6 degrees Fahrenheit (equalled or exceeded 99% of the time).
l (CPCo Verification)
The extreme maximum and minimum temperatures of 86'F and -6*F selected by the NRC are appropriate.
2.3.1.2 Thunderstorms and Lightning Strikes (NRC-SE) l Thunderstorms occur an average of 32 days per year in the site l
region. Based on the annual number of thunderstorm days, the calculated annual flash density of ground lightning strikes is four flashes per l
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square kilometer.
A structure with the approximate dimensions of the
[d 2.3-2 MIO987-0360A-BX01
L O-Big Rock Point reactor building can be expected to be subjected, on the average, to one strike every seven years.
(CPCo Verification)
The NRC values of four flashes per square kilometer and one strike every seven years are reasonable.
2.3.1.3 Hail Storms, Freezing Rain, and Ice Loading (NRC-SE)
On the average, hail storms occur about two days annually, and freezing rain occurs approximately twelve days per year. The maximum radial thickness of ice expected in the site region is about 0.75 inch.
(CPCo Verification)
These values are consistent with values determined for our Midland plant site and are acceptable.
2.3.1.4 Snowfall and Snow Load (NRC-SE)
Mean annual snowfall in the site region is approximately 100 inches.
-Data for the maximum monthly snowfall, the maximum snowfall from a single storm, and the maximum measured snow depth on the ground for the site region is not readily available. Based on the 100 year recurrence accumulated ground snowpack and probable maximum winter -
precipitation for the site region, the noriual winter precipitation-snow load on a flat surface is about 50 pounds per square foot and the extreme winter precipitation snow load on a flat surface is 115 pounds per square foot.
(CPCo Verification)
CPCo agrees with the NRC selected value of 115 lb/fts, 2.3.1.5 Design Wind Speed (NRC-SE)
The design wind speed (defined as the " fastest-mile". wind speed at a height of 30 feet above ground level with a return period of 100 years) acceptable for the site region is 80 miles per hour.
(CPCo Verification)
BRP original design criteria for most buildings was approximately 87 MPH.-
The value of 80 miles per hour will be considered for future design as practicable within the constraints of existing plant design and considering the improvement in terms of its effect1 on overall plant safety.
2.3.1.6 Tornadoes (NRC-SE)
Tornadoes have been reported 25 times during the period 1950-1977 within an approximate 60-mile radius from the Big Rock Point site, excluding the water area over Lake Michigan. On the average, one-tornado can be expected to occur in the vicinity of the Big Rock 2.3-3 MIO987-0360A-BX01 l
1
t.
Point site every year.
Based on the tornado characteristics for tLe site region and the probability calculations outlined in WASH-1300, the recurrence interval for a tornado at the site is calculated to be about 5150 years.
The assumptions used in Regulatory Guide 1.76 provide an adequate design basis tornado for the site region. These characteristics include a maximum windspeed of 360 miles per hour (a maximum rotational windspeed of 290 miles per hour plus a maximum translational windepeed-of 70 miles per hour), a maximum pressure drop of three pounds per square inch, and rate of pressure drop of two pounds per square inch per second.
Based on actual tornado occutrences in the site region area and using-theproceduresdiscussedinWASH-1300,a" site-sgecific"designbasis tornado (with a probabi'lity of occurrence of 10 per year) can be calculated. For the Big Rock Point site, the characteristics of tornadoes occurring within a 60-mile radius are a maximum windspeed of 310 miles per hour (a raximum rotational windspeed of 250 miles per hour plus a maximum t::anslational windspeed of 60 miles per hour), a maximum pressure drop of two pounds per square inch, and rate of pressure drop of one pound per square inch per second.
Because of the infrequent occurrence of tornadoes in the site region (19 tornadoes with available data), the site-specific tornado I
characteristics are based on a very small sample of data which we O
believe does not provide a reasonable degree of accuracy for calculations of safety-related structure design.
(CPCo Verification)
As previously stated in our letter of January 23 1981, design basis tornado parameters from Regulatory Guide 1.76 are not consistent with l
either-the recorded tornado frequency' and intensity data for the site region or with the current state of knowledge on tornado and extreme wind characteristics. More current guidance for the characteristics of a design basis tornado for the site region suggest the following characteristics:
- 1) Maximum wind speed of 250 MPH (combined rotational and translational).
- 2) Maximum translational wind speed of 55 MPH.
- 3) Maximum pressure change of 1.35 PSI.
q These design basis tornado characteristit.s are more reprecentative of the site and will be used instead of the Regulatory Guide 1.76 design basis tornado characteristics.
Since the lake shore environment of the Big Rock Point site exerts an additional moderating influence on severe storm intensity which has not been taken-into account, the above parameters are still considered to be conservative.
2.3-4 MIO987-0360A-BX01
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2.3.1.7 Severe Weather Conclusions j'
(CPCo Conclusious)(Reference 12)
For the specific case of Big Rock Point, a tornado wind speed value 5 would be with a probability on the order of approximately 10 appropriate to ensure that the risk from the single event is small compared to other risk contributors.
If it were assumed that a tornado wind in excess of this value would result in core damage, a very conservative assumption in itself, then tornadoes would still represent only a small percentage of the total residual core damage probability. This is certainly true now, and will remain true after i
any other planned plant modifications are complete. The cost associated with analyses of lower probability conditions more extreme.than these-are simply not warranted for a plant of small core size like Big Rock Point.
Analyses of Big Rock Point' structures'have been completed (refer to Section 3.3 of this Updated FHSR).
These analyses were performed assuming a tornado wind speed of 250 mph. Although this value is t
very conservative in view of the discussion, it was selected some time ago because it was the 10 7 wind speed value determined by our tornado analysis. This wind speed also corresponds to a probability 7
of approximately 2 x 10 in Mcdonald's work.
It is our intent to continue using 250 mph for wind speed.
In the event that specific t
structures are identified which cannot withstand this wind load, then lower values may be selected for further structural evaluations.
If the wind-induced failure (below 250 mph) of.important structures from gross loading or missiles becomes significant with respect to other risk contributors, then these structures will be evaluated using the PRA during the Integrated Assessment. The methodology for the Integrated Assessment has been described previously in CPCo letter of February 2, 1982 and in Chapter 1 of this Updated FHSR.
2.3.2 METEOROLOGICAL'HONITORING The onsite meteorological wind sensor is mounted near the top cf the 240 foot stack approximately two' stack diameters (10 feet) away from the side of the stack to minimize stack influence.
The recording equipment, both analog and digital, are-placed in the Technical Support Center (TSC).
Instantaneous wind speed and wind direction are recorded on one analog strip chart recorder with separate adjacent channels for each parameter.
A digital system is used to compute and display 15 minute averages of wind speed, wind direction, sigma theta, and pasquill stability category. The digital system provides remote interrogation capability for the 15 minute average data.
Secondary meteorological data may be obtained from the National
/}
Weather Service (NWS) through the automated computer system of k,/
Weather Services loternational.
Access to this system from the TSC m
l 1
2.3-5 MIO987-0360A-BX01-
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is via a dial'up' remote terminal. Reliability is assured through the use of redundant computers and multiple telephone access ports.
In addition to data concerning past and present weather, the system will j
also provide the NWS forecast for the plant area. Weather Services
+
International forecasters are available to assist in providing meteorological data interpretation and evaluation on a 24-hour a day basis.
Meteorological data may also be obtained by contacting the National l
Weather Service stations in Sault Ste Marie and Ann Arbor,- Michigan.
2.3.3 ATMOSPHERIC TRANSPORT AND DIFFUSION ESTIMATES An evaluation of Systematic Evaluation Program Topic II-2.C, ~ Atmospheric Transport and Diffusion Characteristics for Accident Analysis, (Reference 13), was completed by CPCo April 6, 1982.- The objective of this topic was to review atmospheric transport a,4 diffusion characteristics utilized to demonstrate compliance with 10 CFR 100 guidelines with respect to plant design, control room habitability and doses to the public during and following a postulated design-basis accident.
Criteria 10 CFR 100 requires that as an aid in evaluating a proposed site, the g;
applicant should hypothesize a fission product release (generally t\\'
assumed to be a result of a substantial meltdown of the core with subsequent release of appreciable quantities of fission products) from the core, the maximum expected leak rate from the containment and the meteorological conditions pertinent to the site. The total dose to an individual at the boundary of the exclusion area over the first two hours after this hypothesized event must be less than 25 rem to the whole body or 300 rem to the thyroid. Also, the NRC' Standard Review Plan (SRP) items of potential hazard from industrial, l
military and transportation facilities should be evaluated and-analysis of the consequences to the plant personne1' of accidents.
involving these facilities should be evaluated. Further, the SRP requests the meteorological data and models used to determine these
~
consequences be presented.
Other pertinent guidance is provided in l
Regulatory Guides 1.3, Assumptions Used for Evaluating the Potential Radiological Consequences of a LOCA for Boiling Water Reactors and 1.145, Atmospheric Dispersion Models for Potential Accident Consequence Assessments at Nuclear Power Plants.
I Summary of Previous Analysis Methods l
Transport of airborne radioactivity from the Big Rock Point site has been calculated by several different means over the past 20 years of plant operation.
Briefly, the techniques and reference documentation l
for each are as follows:
O V
i 2.3-6 MIO987-0360A-BX01 l
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- 1) Siting criteria calculations - Atmospheric diffusion based on Sutton's method for analyses of onsite preoperational meteorology data. Documented in Sections 13 and 14 of the Big Rock Point Final Hazards Summary Report, November 14, 1961.
- 2) Current safety analyses, including Emergency Plan and Emergency Implementing Procedure calculations - Atmospheric diffusion parameters from Regulatory Guide 1.3, assuming ground level or elevated release, dependent upon observed release mode.
- 3) Environmental dose calculations for 10 CFR 50, Appendix I -
Regulatory Guides 1.109 and 1.111 were utilized for computation of doses from elevated releases, based on onsite meteorology data collected February 9, 1961 through February 8, 1962.
Bases and results of these calculations are presented in Consumers Power Company (CPCo) letter dated June 4, 1976.
- 4) Offsite consequences of accidents, Probabilistic Risk Assessment
- Preoperational meteorology data was utilized in accordance with-the methods of WASH-1400. Results of the consequence analyses were submitted by CPCo letter dated March 31, 1981.
Discussion An evaluation of X/Q (Note 1) values at the Big Rock Point Plant was G
presented in Section 14 of the November 14, 1961 Big Rock Point Final Hazards Summary Report (FHSR). As described in Section 14, a meteorological tower was constructed on-a point of land at the shore of Lake Michigan about 2,000 feet to the WNW of the stack.
Trees in the surrounding area were removed. The area = was chosen. so that the measured data would be most accurate for winds blowing toward the Harbor Springs - Petoskey and Charlevoix areas. Hourly data was taken from November 1960 to February 1962. Wind direction was obtained from 36 points (0 to 360). Wind direction and' speed were obtained from sensors located at 32 feet,- 64 feet,128 feet and 256 feet. Temperature data was obtained at 3 feet below the surface of the water, 10 feet, 50 feet, 100 feet, 150 feet, 200 feet and 250 feet above the surface. The data was analyzed using a computer program and hourly values of X/Q were obtained.
The data has since been used in three ways. First, Section 13 of the November 14, 1961 FHSR (Maximum Credible. Accident) used four selected points in the atmospheric diffusion spectrum which encompass the conditions encountered at the site. Atmospheric diffusion methods of Sutton were used for the neutral and unstable cases and Hanford diffusion results (Report HW-54128) were used for inversion cases.
These were compared with site data and found to be conservative.
Radiation doacs at the site boundary and beyond were calculated using the stated diffusion methods. The worst case X/Q at the site boundary 3
for a ground level release was found to be 4E-04 sec/m.
This e
3 for 0-8 comsares with Regulatory Guide 1.3 values of 6E-04 sec/m hours, 2.2E-04 for 8-24 hours, 8E-05 for 1-4 days and 1.7E-05 for 2.3-7 MIO987-0360A-BX01
1 1
l 4-30 days.
Since the radiation doses at the site boundary are very much below the limits given in 10 CFR 100 the actual difference between 4E-04 and 6E-04 is not significant with respect to meeting 10 CFR 100 limits.
The second use of the meteorological data was in the Big Rock Point Probabilistic Risk Assessment (PRA), submitted to NRC by CPCo letter of March 31, 1981. Doses to the public from dominant sequen?cs were calculated using a variety of meteorological conditions with the CRAC code (same methodology as WASH-1400). The conditions were chosen using the sampling technique of WASH-1400. The values for X/Q were not listed in the output of the CRAC code. However, previous analyses 3
of the meteorological tower data show that the worst case X/Q (worst 2-hour interval calculated in accordance with Regulatory Guide 1.145) at the site boundary, 7.5E-04 sec/ma is almost the same as that used in the ITSR.
Control Room Habitability with regards.to external:
events was also presented in'the PRA. Habitability was demonstrated; by showing that the operatcr could isolate the control room ventilation system prior to intake of excessive quantities of toxic gases, smoke, etc. Also, the probability of these events occurring along with the proper meteorological conditions and ventilation failure was small
(<10 4/yr).
The third use of the meteorological tower data was in the CPCo submittal of June 4, 1976 concerning 10 CFR 50, Appendix I.
The meteorological data was used to obtain X/Q and D/Q (Note 2) values, wind roses, monthly and yearly joint frequency distributions, and an annual average X/Q. The methodology used was in accordance with Regulatory Guide 1.111.
This data was then input into the GASPAR-
')
computer code for radiation dose calculations. The maximum annual average X/Q for an elevated release was found to be 2.5E-07 sec/m,
s This occurred in the East sector at 2414 m from the stack. Additional data may be found in Table 3.1 of the Appendix I submittal dated June j
4, 1976.
l CPCo Conclusion i
Because the radiation doses calculated at the site boundary are small, the' demonstration of compliance with-10 CFR 100 limits is not particularly sensitive to the X/Q values used.
Consumers Power Company's intent is to continue with the use of onsite preoperational data for realistic analyses performed-for PRA and environmental dose pu rposes. For all other calculations, Regulatory Guide 1.3 values will be used. Assuming a ground level' release for all unknown accident conditions, the following values of X/Q are applicable at 0.5 miles. Exclusion Area Boundary and Low Population Zone (EAB and LPZ):
i i
0-8 hours 6.0 E-04 i
8-24 hours 2.2 E-04 O-1-4 days 7 4 E-05 4-30 days 1.8 E-05 4
2.3-8 f
MIO??7-0360A-BX01 4
d (X/Q Note 1) - X = the short term average centerline value of the 8
ground level concentration (curie / meter )
Q = amount of material released (curie /sec) 1 (D/Q Note 2) - D = Deposition Constants
]
Q = amount of material released Evaluation Summary The topic of Atmospheric Transport and Diffusion Characteristics for Accident Analysis - Big Rock Point Plant was evaluated by the NRC (Reference 14).
This revised final evaluation of SEP Topic II-2.C.
On June 23, 1982, the staff issued an SER.on Topic II-2.0, which was based on Consumers Power Company evaluation submitted by letter dated April 6, 1982. 'The staff SER derived the X/Q values at the outer boundary of the low population zone (LPZ) based on the minimum distance (805 meters) of a variable outer boundary as defined in the licensee's submittal of April 6, 1982. The actual LPZ boundary is 2.5 miles (4023m) and the LPZ X/Q values have been-recalculated based i
on this distance.
p The evaluation was donc using-the meteorological diffusion parameters 4
Q described in Regulatory Guide 1.3 since no meteorological observations have been made onsite in twenty years. The staff has confirmed that the Regulatory Guide 1.3 parameters are conservative.
This confirmation was done with the methods of the guide as described below and resulted in the values given in Table 1 at the 805 meter exclusion area boundary and at the 2.5 mile (4023m) re-defined distance to the outer boundary of the low population zone distance.
Table 1: Relative Concentration at Big Rock Point 8
Time Relative Concentration X/Q sec/m 0-2 hours EAB 6.7 x 10~4 0-8 hours LPZ 8.0 x 108 8-24 hours 1.7 x 10"8 1-4 days
'5.5 x 10 8-4-30 days 1.2 x 10 s These-values are derived from Figure 3A with the application of the building wake dispersion correction factor in Figure 2 of Regulatory Guide 1.3 for a 500 square meter building surface area. The above values should be used for all contained release accidents.
v 2.3-9 HIO987-0360A-BX01
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(_
Conclusion I
The staff concludes that the X/Q values presented in Table 1 are appropriate for estimating exposures from postulated accidents and should be used in all but steam line break accident calculations.
This provides a conservative assessment compared to the use of
?
methods in conjunction with Regulatory Guide 1.145, which is the basis of current review for new licenses.
9 0
4 1
O 2.3-10 MIO987-0360A-BX01
/M) 2.4 HYDROLOGY Professor James H. Zumberge of the University of Michigan was retained as a consultant on the geology and hydrology of the reactor site and i
its environs. His findings are reported in Volume Two of the November 14, 1961 FHSR.-
in general, the findings are favorable. The surface drainage of the immediate area of the reactor plant building is from the building locations directly to Lake Michigan rather than inland towards inhabited areas and local wells. There appears to be a high probability that any accidental release of material at the immediate location of the plant buildings which penetrated to ground water would also be-drained directly into Lake Michigan.
The surface soils are of types which generally have low permeabi.11ty i
and might be expected to have fair to good ion exchange capacity.
The principal currents in Lake Michigan important to the site for considerations of liquid waste disposal are generally favorable.
Most of the time it is indicated that the current along the plant chore will be from east to west, with significant rapid diffusion into the main body of upper Lake Michigan.
A Hydrological Survey to determine currents and dilution of Lake s
Michigan and Little Traverse Bay in the region near the site was completed during the summer of 1960 under the direction of Professor John C. Ayers, University of Michigan, the Report issued' November 1961 is contained in Volume Two of the November 14, 1961 FHSR.
The NRC completed an evaluation of Hydrology topics as part of the Systematic Evaluation Program (SEP).
The results of this evaluation (Reference 15) and the CPCo evaluation conclusions-(Reference 16) i along with the revised NRC Safety Evaluation Reports (Reference 17 and 18) were utilized to provide the following summary and conclusions for Hydrology issues.
2.4.1 HYDROLOGIC DESCRIPTION l
Refer to Figure 2.1 and 2.2 for Location and Site Plan Maps.
Big-rock Point Nuclear Power Station is located on the eastern shore of Lake Michigan in the northwest section of Michigan's lower peninsula, on the south side of Little Traverse Bay,.....
It is 3 miles north of Lake Charlevoix, an inland extension of Lake Michigan. To the east of the site is Susan Creek, which flows from Susan Lake north j
into Lake Michigan. Plant grade varies from 592.5 to 594 feet MSL at the containment, to 596.6 feet MSL at the stack. Nominal finished grade at the containment structure is 592.5 feet MSL.
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2.4-1 L
MIO987-0361A-BX01
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Lake Water Level The water level of Lake Michigan has varied between-576 and 584 ft msl.. Lake Mich'gan water level experiences long term, seasonal, and short-term v-.r ations. Long-term variations are caused by periods of l
higher or lucr-than-usual precipitation lasting reveral years and extending over a large part of the Great Lakes watershed. The 1
highest recorded (1905-1986) mean monthly water level on northern Lake Michigan near the site was 582.6 ft asl (September 1986).
Seasonal variations average 1 ft between high water in-July and low water in February.
In some years the range may be as high as 2 ft.
Short-term water level fluctuations have a period of a few hours and have produced changes in water level of up to 3 ft.
The~ minimum monthly level of Lake Michigan was elevation 576.4 MSL (USGS-March, 1964).
Watershed The Big Rock Point Plant is located in an area where surface runoff flows directly into Lake Michigan. There are no perennial streams or rivers in this watershed which has an area of between 3 and 4 square miles.
Drainage Site drainage from building areas is generally away from the plant toward Lake Michigan. Some runoff from high ground is diverted around the plant to the lake by-a ditch and culverts on the south and east sides of the site. Drainage areas are well vegetated and relatively flat.
The site is equipped with a storm drainage system, consisting of catchbasins and corrugated metal pipes emptying into Lake Michigan.
The drainage system is necessary to prevent ponding on the site.
Groundwater Groundwater at the Big Rock Point Plant moves north into Lake Michigan from the groundwater divide between Lakes Charlevoix and Michigan.
At the site of the plant, the soil is well drained. Before construction, the water table elevation was approximately 580 ft as1.
A thick sequence of Traverse limestone is overlaid by 50 ft of compact clay till, interbedded with artesian sand zones. The top 10 ft of limestone are badly fractured, and' groundwater conditions are artesian.' The fractured bedrock is directly connected with Lake Michigan and the groundwater gradient responds to short term lake water level variations.
k 2.4-2 MIO987-0361A-BX01
OV 2.4.1.1 Hydrologic Design Bases Roof Loading The roofs of safety related buildings (including Alternate Shutdown Building) are not surrounded by parapets. Therefore, the structural-integrity of the roofs will not be endangered by any local intense precipitation up to and including the Probable Maximum Precipitation.
(PMP).
Ground Water Level The original design basis for hydrostatic groundwater loading of the pumphouse is elevation 583 ft.
The original design value for ground water level at Big Rock Point was 583.6 ft MSL.
In lieu of. an analysis to determine the maximum ground water level, a ground water ~ level at plant grade would be assumed when considering uplift and hydrostatic forces separately-from seismic loadings.
The NRC staff's review of this topic indicates that plant structures can withstand ground water levels at plant.
grade.
In lieu of further analysis to determine the ground water-level to be used in combination with seismic loading, the highest' recorded lake level (approximately 584 f t MSL) may be-used. As part of the SEP r
Topic III-6 evaluation, load combinations involving seismic loading.
and ground water level were considered using'the original design-basis ground water elevation of 583.6 ft MSL. This elevation is sufficiently close to the 584 ft value so that the NRC staff finds it acceptable.
l CPCo has analyzed the stability,of safety related structures for uplifting due to buoyancy for groundwater at elevation 583.6 ft MSL and~found the buildings to be safe. This groundwater elevation corresponds to the 100 year high mean monthly level of Lake'Hichigan and can be taken as the 100 year ground water level for the purpose-of establishing uplift forces.
3
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Safe Shutdown Flood Capability Safe shutdown can be accomplishe'd for flooding events'in which the flooding elevation does not exceed about 594.0 ft MSL at the ' turbine building and about 589.0 ft MSL outside and about 584.0 ft MSL7doside the intake structure. At these elevations, the interior of the
structures would be flooded, but the pumps and electric power supplies necessary for shutdown would be above the flooding elevation.
~
Further, if cooling water could not be supplied by the pumps inside the intake structures, the emergency condenser could operate using the demineralized water storage tank with well water or demin water cooling of the air compressors needed to operate the control valves-3 of the emergency condenser.
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2.4 MIO987-0361A-BX01
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Low Water Level l
The design basis minimum water level in the intake structure is 570.0 ft MSL.
+
Surface Flooding of Safety'Related Structures The design basis water. level for surface flooding of safety related structures, with the exception of the Core Spray Room,-is elevation 583.6 ft MSL.
The design basis for the Core Spray Room is the floor slab at elevation 584.0 ft MSL. The'583.6.ft MSL corresponds to the j
screen, well, and pump house floor slab elevation. The design basis water level for the Turbine Building is the 593.0 ft. floor slab elevation.- The design basis water level for the Alternate Shutdown Panel Euilding is. the 594.5 f t floor' slab elevation.
2.4.2 FLOODS-The potential for a flooding event that could exceed the 594.0 feet '
MSL Safe Shutdown capability at the Turbine Building-is very low.
Flood History There is no record of any flooding at Big Rock Point.
. h 2.4.3 PROBABLE MAXIMUM FLOODING (PMF)
Q.
2.4.3.1 PMF From Probable Maximum Precipitation (PHP) Event' The possibility of plant flooding from local intense It@ was evaluated-for the-following' drainage areas:
- 1) Susan Creek
- 2) Unnamed drainage basin south of the plant site.
- 3) Onsite area Susan Creek The Susan Creek drainage basin lies east of the. plant and drains to Lake Michigan.
The. drainage basin. has an area of 5.7. square miles.
For Susan Creek near the plant site a PMF peak discharge of 20,000 cfs was determined which resulted in afpeak water surface elevation of 590 ft MSL. There is a ridge line above this elevation that separates the Susan Creek drainage basin from the plant, hence,; a PMF
(
on Susan Creek will'not flood the site.
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v 2.4-4 MIO987-0361A-BX01
..m..
}
3 1 named Drainage Basin The unnamed drainage basin adjacent to the plant site has a drainage area of approximately 0.75 square miles. Using a one hour Probable b:U.ium Precipitation (PMP) of 16 inches for this location (current liceni.ing criteria) resulted in a revised analysis as follows:
The watershed is divided into the two sub-areas (a west and east area) by a railroad spur that runs into the plant. The west sub-area was estimated by the NRC staff to have a PNF peak flow of 2,640 cis.
The capacity of the drainage ditch and road cut to the west side of the plant is such that flood elevations would not exceed $94 f t MSL along the opposite side of the railroad bed that comes in beside the turbine building.
Also, this maximum elevation tf 594 ft MSL is at least 2 ft below the railroad bed and thus this flood flow would be blocked from flowing onto plant grade and in and about crucial structures. The peak PMF flow from the east sub-area was estimated as 1280 cis and by the nature of the topography and situation of plant site would drain right onto plant grade. The flow would spread out through the parking lot and then drain through trees and a cleared space along side the turbine building and intake building into Lake Michigan. From an evaluation of the flow depths, the maximum depth at the south end of the turbine building has been calculated to be 593.0 ft MSL (0.4 ft less than the critical (safe shutdown) level of 594.0 f t MSL).
The flow around the intake structure has similarly been calculated to be below all door sill levels, except one door on the south side of the building that leads into the emergency diesel generator room.
Because of the short duration of the peak flow, tightly closed door to the diesel generator room, elevation of equipment in the room, and presence of another dinel generatcr off-site, flooding through this door will not prevcat safe shutdawn.
The flow around the Alternate Shutdown Panel Building was considered during the Facility Change. Hardened protection as defined by RG 1.102 is provided by a retaining wall at elevation 595.5 feet and an embankment at 597.0 feet to divert any flood run-off. The grade around the building was designed to prevent ponding and all penetrations I.
below 5%.0 feet are sealed to prevent in leakage. The sealed door L
sill is at 596.0 feet.
Onsite Area The onsite area analyzed is a small semi-closed basin adjacent to the turbice generator and reactor buildings.
This area is bounded by an access road having an elevation of 595.4 ft MSL and is drained by a culvert system.
If the culvert system is plugged,-vater from a local intense PMP will flow and drain onto plant grade as outlined for the "Onnamed Drainage Basin" above. The possibility of complete blockage of the yard drain is highly unlikely.
2.4-5 MIO987-0361A-BX01
i O
2.4.3.2 PNF Trom Lake Flooding Surge heights resulting from a moving squall line storm and wind storm were determined in the "High Water Level Study" BRP Plant, i
performed by R.M. Noble & Associates, Job No. 13-02, June 14, 1982.
t These surge heights were combined with maximum mean monthly lake levels and the results submitted to the NRC in (Reference 16).
The results of these analyses gave a high water elevation for the moving squall line storm (surge plus maximum mean monthly lake level) of 584.1 ft MSL. From the consultant'a report wave run-up would add l-2 feet to the high water level for the squall line storm; thus the total height would not be greater than 586.1 ft MSL. Static water level from this event would rise in the intake structure to 584.1 ft MSL, about 7 inches above the pump floor level of 583.5 ft MSL.
The pumps located in the intake structure are on pedestals and all electrical controllers and connections are above the calculated level of maximum flooding.
For the wind storm, the high water level was determined from a combination of maximum-mean monthly lake level, plus set-up, plus vave run-up resulting in a high water level of 587.4 ft MSL. That la also below the north plant grade elevation of 590 ft MSL.
2.4.4 PROBABLE MAXIMUM PRECIPITATION (PMP)
The PMP for the Big Rock Point Plant is based on a drainage area of 10 square miles, which is applicable to smaller areas also, it is found to be 22.5 inches for the most severe 6 hour6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> period of the assumed probable maximum storm. This value is taken from Hydro-meteorological Report No. 33, National Weather Service.
The water level from Pt!P would not have a depth greater than flooding depths calculated for the Probable Maximum Flood (PMF) from the adjacent watershed (593.6 ft MSL).
2.4.5 LOSS OF ULTIMATE HEAT SINK (UHS)
An evaluation to determine if the UHS can be lost due to low water level or due to flooding was completed and found that the Technical Specification states that the safety related diesel-driven and electric-driven fire pumps each have a capacity of 1,000 gpm when the water level at the intake is above elevation 570.0. When only these two pumps are operating, the flow through the intake pipe is conservatively estimated at 2,000 gpm and the water level in the pumphouse forebay will be substantially the same as the level in Lake Michigan at the intake. The minimum monthly level of Lake Michigan was elevation 576.4 USGS (March 1964~). Assuming this lake level and applying the setdown of 0.8 feet during the extreme windstorm postulated, the minimum level at the intake and in the pumphouse forebay would be elevation 575.6, well above the level of 570.0 required.
2.4-6 MIO987-0361A-BX01 e
l If the non-safety related circulating water pumps and one service pump were operating at the same time as the fire pumps, the flow would be approximately 53,000 gpm. The head losses in the system would total 3.5 feet and the minimum water level in the forebay would be at elevation 572.1, still well above the level required. This makes it highly implausible that the ultimate heat sink could be' lust due to low water level.
l For the winds associated with a moving squall line or windstorm from the Probable Maximus Flood from lake flooding, the static water levels from these events would rise in the intake structura to a maximum of 584.1 ft MSL, or about seven inches above the pamphouse floor elevation of 583.5 f t MSL. If the plant were operating, the water levels in the wet well would be considerably lower.
Maximum water level in the intake structure was deternined to be below the pumps, pump controllers, and electrical wiring and connections; therefore, the UHS's capability to withdraw water would not be lost due to lake flooding.
2.4.6 FLOOD EMERGENCY OPERATIONAL REQUIREMENTS In the unlikely event of flooding conditions in the Turbine Building, Pumphouse, or Core Spray Room which could disable the demineralized water transfer pump, demineralized water fill pump and fire pumps, O
CPCo has committed to instruct the operators via the Emergency Procedures to request a Fire Department pumper truck to refill the demineralized water storage t,ank with raw water to furnish make-up for the emergency condenser (Reference 19).
Classification of Flood Emergency Conditions for potential flooding from a seiche; water level greater than 583.5 feet (screenhouse floor level 583 feet 6 inches) for flooding of the screenhousa; and intake bay water level less than 572 feet for drought potentially affecting function of safety equipment, or less than 570 feet for loss of l
ultimate heat sink has been included in the Big Rock Point Site L
Emergency Implementing Procedures.
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2.4-7 MIO987-0361A-BX01.
2.5 GEOLOGY, SEISMOLOGY, AND GEOTECWICAL ENGINEERING 2.5.1 BASIC GEOLOGIC AND SEISMIC INFORMATION The following Geology and Seismology descriptions were extracted from the 1961 Final Hazards Summary Report and are reported in this section. Never analyses have been completed since that time, and are reported in subsequent sections of this report.
Geology Professor James H. Zumberge of the University of Michigan was retained as a consultant on the geology and hydrology of the reactor site and its environs. His findings are reported in Volume Two of the 1961 FHER.
Seismology The seismicity of the site area was investigated by Professor James T.
Wilson, Professor of Geology, University of Michigan, who was retained as a consultant for this purpose, and his findings are attached in Volume Two of the 1961 FHSR. The probability that earthquakes of significant intensity will occur in the general site area appears to be very low.
O The importance of earthquakes to plant design was independently investigated by the Bechtel Corporation. Their summary statement of findings is:
"An investigation of the seismic history indicates that this is a region of low seismic activity. The Coast and Geodetic Survey Publication, Serial 609, Earthquake History of the United States, lists earthquakes in the Michigan area as shown below. All of these are classified as intermediate or minor. The nearest recorded carthquake was the one centered near Menominee, approximately 110 miles from the plant site."
Earthquake History as of October, 1959 Rossi-Forel Date L_ocality Intensity Feb 6, 1872 Winona, Michigan 5*
Aug 17, 1877 Southeast Michigan 4-5 Feb 4, 1883 Indiana & Michigan 6
Mar 13, 1905 Menominee, Michigan 5
July 26, 1905 Calumet, Michigan 8
May 26, 1906 Neewenaw Peninsula, Michigan 8-9 Jan 22, 1909 Houghton, Michigan 5*
- Locally felt only.
2.5-1 MIO987-0362A-BX01
)
Since no recorded earthquakes have centered near the plant site, and there is no knowledge of earth tremors having been felt near the site, elaborate or special seismic design features were not considered necessary. However, in keeping with good engineering practice, all structures are designed to resist nominal seismic loading. Otructural design of the plant complies with the Uniform Building Code (UBC).
Horizontal forces based on Zone 1 are used.
The UBC does not clearly cover the reactor containment vessel or the concrete structure and equipment within.
In view of their high degree of rigidity, it appeared prudent to use a seismic factor. equal to the maximum expected ground acceleration at the site. A study of the brief earthquake history of the region led to the conclusion that an intensity of 7 on the Rossi-Forel scale was a reasonably conservative assumption. This corresponds roughly to a ground acceleration of 0.05 gravity. Therefore, a seismic factor of 0.05 was used for this portion of the plant. This is twice the factor required by the UBC for tanks and similar structures, and appears to be reasonable in view of the high rigidity already mentioned.
For the containment vessel itself, earthquake forces do not govern the design, since the wind force on the vessel at the design velocity of 100 miles per hour is greater than 0.05 times its weight.
2.5.1.1 Regional Geology O
The following Regional Geology was extracted from the NRC assessment of Systematic Evaluation Program Topic II-4 (Reference 20).
The Big Rock Point site lies within the Great Lakes Section of the Central Lowlands Physiographic Province (Thornbury, 1965). The dominant festures of this section were caused by glaciation and include lakes, large and small, prominent end moraines, outwash plains, closed basins forming swamps or lakes, eskers and drumlins, and vast areas of rolling ground moraine between the end moraines.
Because of the direction of advance and retreat of the last glaciation, lower peninsula Michigan has a strong surficial northwest-southeast grain. This is also the principle structural trend in Paleozoic rock.
Bedrock beneath the site area consists of limestones and shales of the Traverse Group of Middle Devonian age-(395 million years before present (mybp) to 375 mybp)(Harding cawson Associates, 1979). Three formations of the Traverse Group are exposed in the site region: the Petoskey, Charlevoix, and Gravel Point formations. The bedrock immediately beneath the site is the Gravel Point formation because the Petoskey and Charlevoix have been eroded away.
In the site vicinity, the Gravel Point formation is about 200 feet thick and consists of a variety of rock types but is primarily a gray to brown, fossiliferous limestone that varies from massive to thin bedded.
Interbedded with the limestone strata are beds of shale and shaley v
limestone. Much of the southern shoreline of Little Traverse Bay 2.5-2 MIO987-0362A-BX01
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from Charlevoix to Petoskey is formed by outcrops of the Gravel Point formation.
The rock in the site is overlain by several tens of feet of till, glacial lakebed, glacial outwash, and windblown deposits.
The site is located in the Central Stable Region Tectonic Province (Eardley, 1962).
This province is characterized by major domes, basins, and arches which formed during the Paleozoic Era (570 mybp to 240 sybp). The site lies above the northern flank of the Michigan Basin, which is one of the large tectonic structures in the Central l
Stable Region.
i Bedrock in the site region dips at a low angle.to the southeast toward the center of the Michigan Basin.
Superimposed on this regional dip in the site region, are gentle undulations caused by the presence of minor synclines and anticlines. These folds strike generally northwest-southeast and plunge to the southeast (Harding-Lawson Associates, 1979).
The axes of major folds within Paleozoic rocks of the Michigan Basin also have northwest-southeast i
trends.
Regional jointing in the northern Michigan basin have four major
[
vertical joint sets: N52*E, N46*W, N89'W, and N1*E (Holst, 1982).
p These trends are present in the site region with the northwest set being the most prominent (Harding-Lawson Associates,1979). The joints are usually tight and widely spaced, but locally they have been videned by solutioning.
The sinkholes exposed in the quarries
[
in the area appear to be aligned along major joint trends. Solutioning
?
in the region is discussed in Section 2.5.1.3.
The Michigan Basin has been relatively stable for several hundred million years and is therefore relatively undeformed. Faults have been identified in Paleozoic rocks in the basin, however, no major faults are known in the site area.
The faults in the basin are believed to be pre-Pennsylvanian (more than 330 mybp). They do not offset Pleistocene (10,000 years to 2 mybp) glacial deposits. Minor faults related to ancient solution collapse features have been observed in local quarries. Faults have been postulated, based on seismic reflection profiling in Lake Michigan. These faults have been evaluated and interpreted to be not capable (USNRC, 1978).
Faulting in tne region and site area is discussed in more detail in Section 2.5.2.
2.5.1.2 Site Geology The following Site Geology was extracted from (Reference 20) the NRC assessment of Systematic Evaluation Program Topic II-4.
The site is located on the south shore of Little Traverse Bay where O'
it opens into the northern end of Lake Michigan. Elevations range from about 580 feet mean sea level (f t. ms1) at the lake shore to 2.5-3 MIO987-0362A-BX01
l l
(_,/
+700 ft asl about one mile inland. Elevation at the site is +590 ft l
ms1. From the lake shore to about one mile inland the terrain is a lowland that was once submerged beneath ancestral Lake Michigan. The to1>ography is characterized by low beach ridges with swampy areas in between. From one to five miles from the lake elevations range from
+700 to +900.
This area is a till plain with drumlins that rise I
forty to sixty feet above it.
A drainage divide is present in that area from which surface water and shallow groundwater flow north to Little Traverse Bay and south to Lake Charlevoix.
It is also the j
probable recharge area for minor artesian zones in the soil beneath the site.
The geology of the site was investigated by Consumers Power Company (CPC) in several phases.
Two exploratory boring were drilled into l
the top of bedrock in May, 1959, and seven additional borings were drilled into rock in February, 1960.
In 1979, three borings were drilled to determine the dynamic-characteristics of the soil and rock beneath the site.
The site lies within the outcrop belt of Devonian limestones of the Traverse Group, and the rock directly below the plant is the Gravel Point formation.
It consists of brown and gray, broken to massive limestone with clay seams and interbedded shale, claystone and siltstone layers (D'Appolonia, 1979).
Between depths of cbout 130 and 190 feet tne limestone contains vuggy zones and core recovery and i
RQD (Rock Quality Designation) percentages were low. The limestone bedrock is overlain by about 40 feet of soil.
The upper eight to ten feet consists of dense, fine to coarse sand with gravel and some boulders.
Below the sand and extending to bedrock is very dense till. The till consists of clayey, fine to medium sand with limestone fragments, cobbles and boulders.
The water table varies seasonally, but is usually several feet above the normal level of Lake Michigan.
The till and massive bedrock beneath the site are competent foundation materials, however, the Gravel Point limestone is susceptible to solutioning.
In northeastern lower peninsula Michigan, karst topography is well developed in the Devonian limestones.
This may be due to the relatively thin cover of glacial deposits in that area.
In the site area solution features are more subtle and apparently far less common, but several significant features have been found. A more detailed discussion of limestone solutioning is included in Section 2.5.1.3.
Other than the slight possibility of cavernous conditions beneath the f
site, there are no geologic hazards at this site.
2.5.1.3 The Totential for Subsidence or Collapse Due to Solutioning During the NRC Review of Systematic Evaluation Program (SEP) Topic II-4.B, Proximity of Capable Tectonic Structures in Plant Vicinity,
(
two concerns were identified (Reference 20):
2.5-4 MIO987-0362A-BX01
i i
1
- 1) The possible existence of a large cavern under the site that could ultimately cause subsidence or collapse.
l
- 2) The possibility of the development and enlargement of a new f
cavern during the life of the plant.
j The bases for the concerns were: 1) the existence of three large sinks and an open cavern in the Penn-Dixie and Medusa quarries, which j
are located eight miles to the east and several miles to the southwest respectively; 2) the susceptibility to solutioning of the Traverse Group limestones which comprise the site bedrock; 3) the karst-like i
topography of the rock surface offshore beneath Little Traverse Bay where there is little or no soil cover; and 4) poor rock recovery in the original site exploratory borings and the discovery in three i
recent borings of a vuggy zone between 130 and 190' depths.
in their report entitled " Solution Features in the Traverse Group of Northwestern Michigan" Harding-Lawson Associates, geologist consultants for Consumers Power Company, presented data supporting their conclusion I
that extensive solutioning is not going on in the site area at the present time, nor has it likely been for the past several thousand years. The evidence cited includes: 1) the sinks present in the quarries are filled with undisturbed glacial deposits including sand, gravel and till; thus dating the solution holes as being at least Late Pleistocene age;
- 2) the open cavern in the Penn-Dixie quarry had been bridged by 60 to 80 feet of rock before excavation and was well below the present 1cvel of Lake Michigan, indicating that it probably formed when the level of the Lake was much lower than it is today; 3) movement of groundwater through the rock, related to the wide range of fluctuation of the surface of ancestral Lake Michigan durinF the Pleistocene, is believed to have caused most of the more geologically recent solutioning activity. The level of Lake Michigan and the local groundwater surface have been relatively stable since the lake reached its present level after the close of the Pleistocene;
- 4) the site region is covered by a blanket of relatively impermeable soil, causing most precipitation to run off rather than percolate down and move through the rock; 5) extensive karst topography is not apparent at ground surface in the site area.
Based on the (vidence available to date, it is not likely that significant solution activity is going on in the rock beneath the site, ner is it likely that there are large caverns beneath the site
~t sufficiently close to the surface to cause subsidence or collapse beneath the plant, as indications of this condition would probably have already been observed during or shortly after construction i
twenty years ago. However, because of the scarcity of information on the condition of site bedrock it was considered prudent to perform additional studies to confirm its competency.
The additional studies were completed and the results and conclusions O
on these concerns were addressed in (Reference 21) as follows:
1
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CPCo contracted with Conanonwealth Associates, Inc (CAI) of Jackson, Michigan, to investigate the possible existence of solution cavities beneath the plant.
CAI reported its conclusions in the report "An Investigation Into the Possible Existence of Solution Cavities Beneath the Big Rock Point Nuclear Power Plant Near Charlevoix, Michigan," February 1983.
In that report the consultant concluded that the geologic processes that created solution features in tLe area have not been active since the last episode of glaciation, and there is insufficient information to confira either the presence or sbsence of cavities beneath the site.
Evaluation Sununary Conclusion On the basis of the evidence available to date, it is not. likely that significant solution activity is going on in the rock beneath the site, nor is it likely that there are large caverns beneath the site sufliciently close to the surface to cause subsidence or collapse beneath the plant, because indications of this condition would probably have been observed during or shortly after construction 20 years ago.
The staff concludes that there is insufficient benefit to be gained from conducting additional onsite investigations; therefore, no further action is required.
i One other concern raised during SEP Topic II-4.B review (Reference
- 20) was the possibility of subsidence and collapse due to the O
dissolution of salt at depth beneath the site. Wold (1980), based on the examination of the available seismic reflection profiles in Lake Michigan interprets the presence of faults, which he attributes to collapse structures formed by the dissolution of salt within the zone i
of outcrop of Middle Suurian (445 mybp) through Middle Devonian (360 mybp) strata. The si a lies within this zone. Based on NRC review, they don't consider this phenomenon to represent a hazard to the site because'.
1) the site is underlain by a relatively thick section (400/500 feet) of Upper Devonian rocks with little or no salt deposits (based on studies by Dr. T. Buschbach of outcrops, quarries, hydrocarbon exploratory borings, and water well logs); and
- 2) the section of rocks that are of concern, in addition to being overlain by a thick sequence of Upper Devonian rocks, are also overlain by 40 feet of glacial deposit.s. There is no apparent evidence of collapse features at depth in the glacial soil at the site.
Evaluation Summary Resolution Salt deposits lie at depth beneath the site.
It has been postulated that-inferred faults in Lake Michigan are the result of collapse due to dissolution of salt. We conclude that this phenomenon doesn't O
present a hazard to the plant because of thick limestones over the V
salt deposit, and there is no evidence of it having occurred in at l
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2.5-6 l
MIO987-0362A-BX01
f s
least the last 10,000 years in the Pleistocene soils that cover rock in the site area.
2.5.2 VIBRATORY GROUND MOTION As discussed is Section 2.5.1 above, the i
probability of earthquakes of significant intensity to provide vibratory ground motions which would cause major damage at Big Rock Point is very low. As a result of the Systematic Evaluation Program f
(SEP), (Reference 28) the seismicity of the Big Rock Point vicinity l
has been recently reviewed by experts employed by the NRC, the SEP l
Owners Group and by Consumers Power Company (see NUREG/CR-1582 and
" Eastern United States Tectonic Structures and Provinces Significant to the Selection of a Safe Shutdown Earthquake," Weston Geophysical, August 1979).
Based on approximately 200 years of reasonably reliable earthquake history and the known geological and tectonic structure of the area, the experts seem to agree that a design basis earthquake with a return period of one to ten thousand years would be 0.05 to 0.07 g.
Earthquakes of this size do not cause major damage to even l
poor quality construction.
v If, in addition to the above, a minimum design earthquake is assigned for the er tire eastern United States without regard to structure or location, the design earthquake increases as in Attachment 1 to the 7
August 4, 1980 NRC letter to approximately 0.10 g.
Typical industrial construction is not usually damaged by this Icvel of earthquake, r-'
Steel and reinforced concrete construction as used at Big Rock might,
( j) at worst, suffer minor cracking.
Finally, p;eliminary calculated results from the Big Rock structural evaluation indicate that majcr structural elements of all safety-related structures will remain below code allowable stress when subjected to an 0.11 g earthquake of the type shown in Attachment I to the August 4, 1980 letter.
In summary, earthquakes are not very probable at Big Rock Point.
Even for long return periods, the earthquake is not predicted to be large enough to cause major damage to quality industria'4 construction.
Preliminary calculations for Bir; Rock structures show no significant damage occurs to the structures i' rom earthquakes of the size proposed in your letter.
Independent work being done for the Big Rock Probabilistic Risk Assessment indicates very long return periods for earthquakes of this size. We conclude that continued operation of the Plant while the seismic analysis is completed is entirely acceptable for the above enunciated reasons.
Summary of Seismic Design Considerations A summary of the Big Rock Point seismic resistance from Systematic Evaluation Program (SEP) Topic III-6 Seismic Design (Reference 27) is provided below:
O 2.5-7 MIO987-0362A-BX01
i The initial seismic criteria as applied to Big Rock Point were based i
on static requirements of the 1958 edition of the Uniform Building Code. The containment design was based on a 0.05g horizontal static coefficient.
The turbine building, concrete stack, intake structure, i
control room and rad waste storage buildings were designed based on a 0.023g horizontal static coefficient.
Piping design for seismic resistance was limited to the reactor vessel supports and NSSS major piping. These components incorporated a 0.0$g and a 0.025g horizontal j
static coefficient in the respective designs. The RDS was designed in 1974 in accordance with seismic design requirements as they j
existed at that time. These compare with more recent requirements 4
which assume a 0.12g (Reg Guide 1.60) safe shutdown earthquake. The Alternate Shutdown Panel Building design and electrical conduit for alternate safe shutdown also utilized the 0.12g (Reg Guide 1.60) safe i
shutdown earthquake requirement.
A complete review of the seismic design adequacy of the Big Rock Point Plant was initiated by the NRC staff early in 1979 as a part of Systematic Evaluation Program Topic III-6. Plans were developed by Consumers Power Company and submitted April 25, 1979 with respect to important structures which were to be analyzed. The staff requested that major. portions of the primary coolant loop be included in this initial structural analysis in July 1979.
Initial structural analyses i
employed Reg Guide 1.60 Spectra (anchored at.12g) while awaiting
('
staff approval of a site specific seismic response spectra. Preliminary results from analysis of 15 major site structures plus the primary coolant loop were submitted January 9, 1981 with the final report (by D'Appolonia) published August 26, 1981.
In July 1979 (IEB 79-14), the staff required all licensees to verify that the configuration of safety-related piping systems corresponded to that assumed in the plants existing design analysis. This activity t
resulted in an inspection of approximately 6000 feet of safety-related piping at Big Rock Point including examination of pipe geometry,.
l support desis,n, embedments, attachments and valve location and orientation. Results associated with this activity were published in October 1979, and were to be used eventually as input to the piping design review associated with SEP Topic III-6.
In January 1980, the staff published a formal request for the immediate identification and evaluation of important electrical equipment and its anchorage. As a part of the request, auxiliary failurer which could result in the disabling or failure of safety related equipment (such as gas bottles, dollies, etc) were to be identified and evaluated as well. This Systematic Evaluation Program work resulted in the identification, analysis, and anchorage of over 50 equipment items.
Among the major equipment important to safety were motor control centers, distribution panels, batteries and transformers. As requested,
~
auxiliary equipment was also evalua W and included tanks, containers, cabinets and lighting located in the vicinity of important safety
.g equipment.
The majority of the electrical equipment anchorage work
(
was completed by March, 1981.
l l
2.5-8 l
MIO987-0362A-BX01
~.
In April,1981 the staff requested a firm schedule for completion of
[
seismic design review activities.
Included in their request were not only the primary coolant loop but verification of fluid and electrical distribution system integrity and analyses of the integrity and functionability of important mechanical and electrical equipment.
Also requested was justification for continued operation while the i
additional work was in progress.
At this time the cost of evaluating this single SEP topic was well in excess of one million dollars and had at least as much evaluation and analysis awaiting completion as had been accomplished to date.
In addition, work was ongoing in the development of-resolutions to NRC questions raised with respect to work submitted to date. As part of its justification submitted June 19, 1981, Consumers Power Company questioned the benefits of such an extensive, deterministic based eevaluation of the Big Rock Point
+
structural design. Referenced were the results of the Big Rock Point risk assessment published in March,1981 which suggested that seismic concerns represented only a small contribution to the total risk of operatten. Consumers Power Company proposed the detailed analyses completed to date used in conjunction with augmentation of the Probabilistic Risk Assessment (PRA) arguments would demonstrate a basis for concluding that seismic risk at Big Rock Point was small compared to other contributors, and that further deterministic analyses were not necessary.
In a site visit on June 30, 1981, the staff insisted that the deterministic approach was necessary and that the proposal to use risk assessment as a basis for continued operation had little promisc of working. Consumers Power Company submitted a plan for future evaluations with respect to SEP Topic III-6 on July 27, 1981 and on September 29, 1981, the staff concluded that our plan and justification for operation in the interim were acceptable. Justification was based on analysis of plant structures and systems performed to date, apparent inherent seismic resistance of remaining systems and structures, and the low seismic hazard associated with the Big Rock Point site.
In April,1982, as a part of its review of Consumers Power Company seismic evaluations that had been completed, the staff raised questions with respect to soil properties assumed in these analyses. This placed into question the adequacy of the Reg Guide and site specific spectra used in the analyses.
In August 1982, work explicitly aimed i
at analysis of piping and equipment was suspended (except for model development) while these uncertainties were resolved.
On October 19, 1982, the staff issued a draft Safety Evaluation Report (SER) with respect to the status of the seismic reevaluation of Big Rock Point. This report identified several areas of concern that the staff had with respect to the appropriateness and completeness of analyses performed to date. As a result, the staff stated that they were unable to come to a conclusicn with respect to the scismic
()
capability of the Big Rock Point Plant. They did conclude, however,
\\s /
that there existed inherent seismic resistance in the design of the 1
2.5-9 MIO987-0362A-BX01
plant, that operation was justified in the interim whil.e the Integratei Assessment was performed and that alternate approaches to resolving this topic should be investigated.
A meeting was held with the staff in December, 1982 in which Consumer:
Power Company was encouraged to respond to the staff comments presented in the October SER. The staff concluded that because of the significant cost of continuation of the seismic analysis program it was recommended that Consumers Power Company consider and propose alternate approaches.
These approaches could include bounding analyses with selected plant upgrading assessments of the consequences of failures, comparison of probabilistic risk and representative cross-sections of current i
plants, or combinations thereof. The resulting approaches would be considered in the Big Rock Point Integrated Plant Safety Assessment.
In June, 1983, explicit response to the staff's concern in their draft SER were provided in addition to the Iternatives Consumers Power Company was proposing for final resolution of this SEP topic.
The alternatives included a comparison of the risks associated with Big Rock Point Plant consequences on the health and safety of the public in comparison with a newer typical facility, as the staff sugRested.
Also an approach to identifying, evaluating and upgrading 1
the seismic " weak-links" at Big Rock Point was presented with explicit results.
Commitments were made to upgrade the report. to more completely identify the perceived weaknesses associated with the plant design, O
if t.he staff approved of the approach.
In September and November of 1983 the staff and Consumers Power i
Company presented joint testimony before the Advisory Committee on 3
Reactor Safeguards in regard to the alternate " weak-link" approach.
The ACRS was requested to comment on the appronriateness of the proposed approach.
In their testimony the staff concluded that the-
" weak-link" approach was prudent and correct for Big Rock Point.
They intended to monitor its implementation in the form of analyses and backfits before concluding as to the level of protection afforded by the plant. design against seismic events. Preliminary conclusions by ACRS members indicated that it was not necessary to get Big Rock Point up to the level of a new plant and that the " weak-link" approach was appropriate.
In May 1984, the final Integrated Plant Safety Assessment was p%blished by the staff (Reference 21).
In that' report, both the staff anc the ACRS conclude that the proposed " weak-link" approach is approl riate and that they will continue to monitor its implementation.
NRC Evaluation Conclusions (Reference 21)'
The following v.as exuacted from NUREG 0828, Final Report May 1984, Section 4.12 and supports the evaluation above.
(d
's During its topic evaluation, the staff concluded that the criteria and analyses supplied by the licensee for structures, buried piping, 2.5-10 MIO987-0362A-BX01
and portions of the reactor coolant loop piping were not adequate to resolve questions concerning analytic uncertainty or to quantify the effects of simplifying assumptions. The sein,mic analyses performed to date are not in accord with either Systematic Evaluation Program (SEP) or Standard Review Plan (SRP) current criteria. The licensee has indicated that it is not economically feasible to perform the analyses required to demonstrate seismic capability and quantify analytical uncertainty. The staff agrees that considerabic detailed analysis would be required.
As an alternative, the licensee has proposed to evaluate the seismic resistance of equipment important to safety using a combination of probabilistic methods and deterministic analyses....
I The staff concurs with the licensee's proposed approach to selective seismic upgrading. The original design of Big Rock Point included a static horizontal load for structures.
The seismic analyses performed under Topic III-6 have demonstrated that there is inherent seismic resistance in the design; however, to complete the analysis and any modifications necessary to dem'nstrate a consistent seismic capability for all rafety-related equipment. and structurca would be very time consuming and expensive because of the lack of original seismic design analyses, the compicx nature of the "as-built" plant, and (in some cases) lack of original construction details needed to perform seismic analyses. The offsite dose analyses performed in conjunction q
with SEP topics and the licensee's PRA have demonstrated that the Q
relative consequences of accidents, even those involving core melt, are very low because of the small plant size and low population distribution around the plant site, In view of these considerations, the staff concludes that the approach proposed by the licensee (ie, to selectively upgrade the " weak links" in the systests and structures necessary to mitigate accidents that would be expected to result from seismic events) is reasonable and, if pr7erly executed, would provide sufficient seismic resistance so that the bealth and safety of the public could be ensured.
2.5.2.1 Response Spectra Various seismic design Response Spectra have teen used in the Systematic Evaluation Program to demcustrate the seismic design adequacy of Big Rock Point:
In the August 4,1980 NBC letter, the preliminary scismic input grcund response spectra recommended for use in the interim until F
Wa-.
g 2.5-11 MIO987-0362A-BX01
i
-~
(.
the final NRC staff decision on Site Specific Spectra at SEP i
sites was provided at the 50th percentile of 0.102g and 5%
j damping.
j This Site Specific Response Spectra for SEP Plants Located in the Eastern United States was finalized and issued by NRC letter to all SEP Owners (except San Onofre) June 8, 1981 (reissued June 17, 1981).
This Final Site Specific Spectrum recommended ground response spectra (5% damping) was 0.11g.
In the CPCo April 25, 1979 letter and the July 26, 1979 meeting, we agreed to construct structural models and exercise them using an example spectra. The example spectra is a Reg Guide 1.60 l
spectra anchored at 0.12g.
This seismic input consists of a sample problem earthquake having a zero period horizontal ground acceleration equal to 0,12g.
In May of 1982, a Site Specific Response Spectrum was prepared for CPCo by Weston Geophysical Corporation and was derived by CPCo independently from the NRC efforts in this area. This report was submitted to the NRC on May 5, 1982. A copy of from the May 5, 1982 letter is provided as Figure 2.7 of this report and shows a plot of the spectra resulting from the Wes*4a work as well as a 0.12g Reg Guide 1.60 spectrum and the f-site specific spectrum issued by the NRC (letter of June 8, 1981)
(
of 0.104g.
In the Spent Fuel Pool Expansion Hearings, an affidavit in support of Motion for Extension of Time (May 3, 1982) was filed noting possible anomalous site conditions which could affect the seismic input ground motion at Big Rock Point.
i The NRC staff issued an " Assessment of Possible Soil Amplification at Big Rock Point Site," June 30, 1982. This evaluation of the l
possible need to modify the seismic input ground motion because of shallow soil conditions at the site concluded that the original issued ground response spectra are still appropriate (ie, 0.11g).
Extensive studies of amplification at Big Rock Pofut may only be of marginal safety significance. The seismic hazard at this site is so low r,uch that the chance that there will be amplified ground motion in excess of the previously identified spectrum (Memorandum from R. Jackson to W. Russell, dated May 20, 1981 attached to the June 17, 1981 NRC letter) is extremely small.
Conclusions It has been Consumers Power Company's position that safety-related plant improvements or additions should be designed in accordance with current regulatory criteria as' practicable within the
[\\m-)' -
of the improvement in terms of its effect on overall plant safety.
constraints of the existing plant design and considering the nature l
I 2.5-12 MIO987-0362A-BX01
U In this regard we would intend to use seismic design criteria based either on the R, Guide 1.60 (0.12g) earthquake or the NRC site 4
specific (0.104g) earthquake as both are acceptable seismic design bases. Big Rock Point is also involved in resolution of unresolved Safety Issue A-46 for Seismic Qualification of Equipment in Operating Nuclear Power Plants through Generic 1.etter 87-02 as a member of a Seismic Qualification Utility Group (SQUG).
]
2.5.2.2 Historical Hazard Analysis The following historical hazard analysis summary was extracted from (Reference 29) and is included in this report to provide additional 1
seismic hazard analysis which justifies the conclusion by the NRC j
that further extensive studies of amplification at Big Rock Point may i
only be of marginal safety significance:
1 The seismic hazard at Big Rock Point is very low. According to a recent compilation of historical and instrumentally recorded earthquakes 4
(NUREG/CR-1577) the closest earthquake occurred at a distance of more than 100 km from the site aed this event was of Modified Mercalli Intensity V or less.
In addition, Chen and Bernreuter (1982) performed i
a historical hazard analysis ie, using only actual events in the historic record (not moving them) and a ground motion model which estimates ground motion (peak acceleration) at Big Rock Point from m
these events. They estimated the return periods associated with peak accelerations at the site. Depending on the ground motion model used the peak acceleration associated with 4000 year return period varied i
from 0.03g to 0.lg.
The high value was determined using a ground motion model that according to Chen and Bernreuter (1982) may over cmphasize the distant (over 1000 km) 1811, 1812 New Madrid Earthquakes.
Indeed, using the most recent ground motion model (Nuttli and Hermann, 1981), results in peak accelerations on the order of 0.001g at a distance of 1000 km.
Excluding the New Madrid events (which according to Chen and Bernreuter, 1982, have estimated return periods on the order of 500 to 1000 years) results in a peak acceleration at Big Rock Point of 0.03g associated with the 4000 year return period.
While no attempt is made to correct for completeness of the data or delineate earthquake zones t.hese studies indicate that based upon 200 i
years of earthquake history the ground motion occurring at Big Rock Point has been very low and that simple projections of this history using current ground motion models, to long return periods on the order of thousands of years yields peak accelerations well below that originally recommended (0.lg) for the cite.
Based on the above, the chance that Big Rock Point will experience earthquake ground irotion of any significance is extremely small.
2.5.2.3 Safe Shutdown Earthquake (SSE) 10 CFR Part 100, Appendix A requires that the Safe Shutdown Earthquake (SSE) be defitted by response spectra corresponding to the expected
)
iv 2.5-13 MIO987-0362A-BX01
f~x()
maximum ground accelerations. Reg Guide 1.60, Revision 1 describes methods for defining this response spectra as follows:
Maximum (peak) Ground Acceleration specified for a
- ven site means that value of the acceleration which corresponds to zero period in the design response spectra for that site. At zero period the design response spectra acceleration is identical for all damping values and is equal to the maximum (peak) ground acceleration specified for that site.
For the Big Rock Point site, this maximum (peak) ground acceleration is graphically depicted in the Design Response Spectrum in Figure 2.7 as the Reg Guide 1.60 at 0.12g.
It should be noted that the 0.12g Reg Guide 1.60 Spectrum envelopes both the NRC Site Specific Spectra and CPCo's Big Rock Point Site Specific Spectra as discussed in 2.5.2.1 above.
2.5.2.4 Operating Basis Earthquake (OBE)
Values have not been tabulated or depicted for the Big Rock Point OBE, however these values are normally one half of the Safe Shutdown Earthquake.
2.5.2.5 Site Specific Seismic Floor Response Spectra
(\\
Derivation.of Site Specific Seismic Floor Response Spectra for the seismic safety margin evaluation of Big Rock Point Plant are contained in D'Appolonia Report dated August, 1983 (Reference 30) and in (Reference 23).
2.5.3 SURFACE FAULTING The following NRC assessment of the capability of faults in the site region was extracted from Systematic Evaluation Program Topic II-4.B.
Proximity of Capable Tectonic Structures in Plant Vicinity (Reference 20):
Major faulting has not been racognized in the subregional area around the site. Although the Michigan Basin has a long history (hundreds of million years) of relative tectonic stability, large-scale structures have been mar; ed within it, primarily in areas of hydrocarbon exploration and production.
During geological studies in regard to the (proposed) Midland Nuclear site, a pattern of orthogonal northwest-northeast mild deformation was mapped on several Mississippian and Devonian stratigraphic horizons (USNRC, 1982). Faults were inferred to be associated with that pattern. These investigations showed that the inferred faulting
/'.'
could not be demonstrated to extend upward into overlying Pennsylvanian strata, therefore the faults, if they exist are at least Late
\\
Mississippian in age (more than 330 mybp). Deformation was also 2.5-14 MIO987-0362A-BX01
i l
identified in Pennsylvanian rocks south and east of the Midland site.
It was demonstrated however that these distortions were formed by sof t sediment deformation that occurred during or shortly after deposition and were not tectonically derived (USNRC, 1982). All
{
faults in the region around the Midland site were concluded to have occurred prior to the Pennsylvanian period (more than 300 mybp).
That conclusion is consistent with observations on the regional geologic history of the Michigan Basin (Haxby et al.,1976; Cross, 1982; and Fisher, 1979 and 1982).
The intrabasin structure is dominated by a subparallel set of northwest-southeast anticlinal flextures that are asymmetric in cross-section with the strong dip toward the basinward side. They are best defined in the eastern, southesstern, and centrrl portions of the basin.
l Several prominent features located far to the south of the plant site, namely the Howell antiline, Albion-Ccipio syncline, and the Lucas-Monroe monocline, are postulated (but not proven) as having west-flanking in their Paleozoic strcta (USNRC 1982).
i Several faults are located on the southeast flank of the Michigan Basin that have mid-Paleozoic displacements. These are the Bowling Green Fault, located in northwestern Ohio, with youngest displacement being of upper Silurian age, and faults associated with the Chatham sag, Ontario, Canada. The latter system of faults, which includes 7
the Electric and Osborn faults, indicates that the Chatham sag was e
inactive after middle Devonian time (more than 350 mybp).
A series of major folds in the Paleozoic rocks characterizes the Michigan Basin (Holst, 1982). A prominent northwest striking joint set may be related to this structural grain.
It is likely that faults are associated with these structures, but based on regional associations, these faults are not capable.
During the staff review of the Wisconsin Electric Company's (WEPCO)
Haven site several sources of seismic reflection data indicated the possible presence of NNE and NW trending faults beneath Lake Michigan.
The staff reviewed these and other data gained during WEPCOs investi-gation, and studied the seismicity of the Lake Michigan region.
Based on that review (memo from R. Denise to B. Grimes, October 11, 1978) the staff concluded that 1) faulting within Paleozoic strata in the Central Stable Region is widespread in rocks that are Mississippian age and older (320 mybp), therefore, the discovery of faults, or the inference of faulting within Mississippian or older units beneath Lake Michigan is not surprising; 2) no h.storic earthquake epicenters t
have been plotted in Lake Michigan, and 3) the faults beneath Lake Michigan are geologically old and pose no potential to increase the earthquake hazard of the region.
There are other structures like those described above within and around the Michigan Basin. All of these structures are considered by O
the staff to be post Devonian to pre Pleistocene (345 mybp to 1 mybp) with most activity occurring in the Late Paleozoic.
This conclusion 2.5-15 MIO987-0362A-BX01
i is based on the observation that all Paleozoic rocks are affected by i
the structures, with Mississippian being the youngest; and there is I
no evidence that the faults cut Pleistocene sediment.
l Several minor faults have been reported in the site area. One small fault mapped by Pohl (1929) was reported as not displacing the Petoskey formation, and is therefore more that 360 million years old.
Faulting described in the Penn-Dixie quarry (Walden,1977) is related to solution slumping because they do not extend below the sinkhole in
(
the north wall (Harding-Lawson Associates, 1979).
We assume that there are probably minor faults in bedrock in the site area because faults have been mapped in Paleozoic rocks throughout the Michigan Basin. There is no evidence, however, of fault displacement of Pleistocene soils t. hat cover bedrock in the region. We conclude that there are no faults within the site region'that could be expected to localize earthquakes in the site vicinity, or that could cause surface displacements at the site.
Based on our review, it is the staff's conclusion that there are no tectonic faults that represent a hazard to the continued safe operation of the Big Rock Point Plant.
Evaluation Summary Conclusion Geological investigations that have been carried out in the site area p
and throughout the Michigan Basin have not found any indicat. ion of fault movem3nt in the recent geologic past. Evidence has been found throughout the tasin that indicates that the latest movement that occurred along known faults was at least 330 million years ago. No evidence has been found that faults displace Pleistocene deposits.
No faults have been identified at the site, however, if they exist, they like all known faults in the Michigan Basin are not capable according to Appendix A 10 CFR, Part 100, 2.5.4 STABILITY OF SUBSURFACE MATERIALS AND FOUNDATIONS The following assessment of the foundations and earthworks properties under antiefpated loading conditions including earthquakes was extracted from Systematic Evaluation Program Topic II-4.F, Settlement of Foundations and Buried Equipment (Reference 22):
Figure 2.3 on Page 2.1-11 shows the general layout of the plant.
In addition to the structures shown in Figure 2.3, an Offshore Intake Structure and Offshore Intake Pipe Line are also part of the plant.
These supply the cooling water for the operation and also safe shutdown of the plant. The Offshore Intake Structure is a-submerged trestle structure located approximately 1200 feet offshore in Lake Michigan where the depth of water is approximately 30 feet.
The Offshore Intake Pipe Line connects the Intake Structure to the Screenwell-Pumpbot.s.c/ Diesel Generator / Discharge Structure (the total length of the pipeline is about 1450 feet).
IU 2.5-16 MIO987-0362A-BX01
((
Seismic safety margin evaluation of BRP by D'Appolonia (Reference 23) i presents detailed description and functions of these safety related structures, systems and components.
(NOTE: Since issuance of the NRC Safety Evaluation Report (Reference 22), BRP has constructed an Alternate Shutdown Panel Building. This building was analyzed for settlement and for the seismic safe shutdown earthquake ground acceleration of 0.12g by CPCo and the following evaluation data is applicable to this structure.)
The foundations of the safety-related structures, systems and components that were considered in the NRC SEP Topic II-4.F settlement evaluations are:
Reactor Building Turbine Building Screenwell-Pumphouse/ Diesel Generator / Discharge Structure Fuel Cask Loading Dock / Core Spray Equipment Room Intake Structure (offshore)
Intake Pipe Line (offshore)
Buried Fire Main Piping System and Electrical Cables (NOTE: Alternate Shutdown Panel Building evaluated by CPCo)
Foundation Data Source of Information Geotechnical data available for this site are:
1.
" Soil Report," Big Rock Point Plant, Charlevoix, Michigan by Soil Testing Service, Inc., March 7,1960.
2.
" Big Rock Nuclear Power Plant, Hydrological Survey," Report by Great Lake Research Division, Institute of Science and Technology, University of Michigan for Consumer Power Company, November 1961.
3.
" Geophysical Cross-Hole Survey," Big Rock Point Nuclear Power Plant, Charlevoix, Michigan, January 1979, by D'Appolonia, Consulting Engineers.
The first set of data, Soils Report (1960), presents the geotechnical investigation and analyses performed in connection with the construction
,q of the power plant. The investigation consisted of drilling seven (d
borings and performing laboratory tests on noil samples recovered from the borings.
2.5-17 MIO987-0362A-BX01
O The second set of data presents a description of the lake bottom as observed by divers during hydrological survey.
The third set of data, Geophysical Cross-Hole Survey Report (1979),
presents the geophysical investigations performed to establish the dynamic properties of the materials at the site. This investigation consisted of drilling three borings and performing cross-hole tests to determine the compressional and shear wave velocities as a function of depth.
In addition, data gathered during NRC site visits were also used in the evaluation.
Subsurface Conditions Plant Site The plant site (ground surface at average elevation 590.0 feet) has approximately 40 feet thick soil overburden overlying limestone bedrock; the overburden is compoacd of:
Seven to ten foot thick, medium dense to dense, fine to coarse sand with some gravel and limestone chips, and varying amount of Filt. This is a glacial outwash deposit.
Standard penetration O
test (ASTM D1586) blow count ranged from 8 to 33.
The ground water table is controlled by the adjoining lake level and is at an approximate depth of 8 feet below ground surface.
Thirty to thirty-five foot thick, fine to coarse sand with some clay, trace of silt and gravel.
This is a very stiff cohesive glacial till. The standard penetration test blow count ranged form 19 to 162.
Sand lenses were occasionally encountered in this stratum.
The bedrock is limestone. The upper 15 to 17 feet of this is highly fractured and weathered fossiliferous limestone with seams of clay. The core recovery in this zone ranged from 0 to 90 percent and the RQD (Rock Quality Designation) ratio ranged from 0 to 26.
The highly f ractured limestone a one is underlain by approximately 75 foot thick limestone with occasional seams of clay. The core recovery in this zone ranged from 40 to 100 percent and the RQD ratio ranged from 0 to 84.
This limestone is underlain by approximately 50 foot thick, highly fractured limestone with vugs..The core recovery in this q
zone ranged from 10 to 100 percent and RQD ratio was 0.
1 The fractured vuggy zone is underlain by slightly broken to
_3 massive limestone. The core recovery in this zone rauged from 52 l
to 100 percent and the RQD ratio ranged from 55 to 90. The MIO987-0362A-BX01
i
,rN
[
s_-
deepest boring at the site (201 feet deep) was terminated in this stratum.
Offshore Intake Structure and Offshore Intake Pipe Line The surficial material on the lake bed along the intake pipe consists of an initial stretch of beach zone followed by boulder-pavement zone and till-col-ble zone. Offshore intake structure is located in the till-cobble zone. The intake pipe line runs from the offshore intake structure to the screen well pumphouse/ Diesel Generator /Diset,arge Structure.
Contours and approximate boundary of the lake bottom material found offshore of the BRP site are presented in BRP llydrological Survey contained in Volume II of this Report.
The beach zone, approximately 250 feet wide, consists of cobbles, pebbles and sand, and is continuously subjected to agitation by wave action. This includes zone of water depth shallower than five feet.
The boulder pavement zone, approximately 500 feet wide, is a spread out area of cobbles and small boulders set closely together on the bottom. Wave erosion has removed the clay and sand content of the glacial till (upper two feet zone) leaving the pebbles, cobbles and boulders to form the lake bottom, termed " boulder Pavement Zone."
This boulder pavement is approximately two feet thick and is underlain r~'s by glacial till.
In the till-cobble zone, the surficial boulder pavement zone mentioned above is not present and the till is exposed at the lake bottom.
Soil Properties In addition to the standard penetration test blow counts, the test data available are:
1.
insitu moisture content (6 to 10 percent) of till.
2.
unconsolidated undrained triaxial shear test on till samples recovered from split-spoon sampler (ASTM D1586) indicated an undrained shear strength of 3 TSF cohesion and 30 degrees angle of internal friction.
It is concluded that this till is very stiff and highly overconsolidated.
2.5.4.1 Settlement of Structures Plant Site Structures All the seismic Category I buildings within the plant site are founded on glacial till stratum which is present at the plant site at a nominal depth of eight feet. Based on the available data (presented 7 ~s
(
)
in Soil Properties 65ove) it is concluded that the glacial till is
\\'/
very stiff (cohesie 3 TSF) and heavily overconsolidated. The 2.5-19 M10987-0362A-BX01 i
i l
maximum settlement due to the load from the structures was estimated by the applicant during the design stage to be minimal (less than 0.5 inch) and would take place within a short period after load application.
(Note, since this evaluation was completed, the Alternate Shutdown Panel Building was constructed, with an analyzed Lettlement of 0.36 inch.)
The licensee had not initiated any settlement monitoring program and has no records of any settlement monitoring. The plant has been in operat. ion for nearly 20 years and there is no evidence of any excessive settlement. A few minor cracks were noticed during the site visit, but these minor cracks are judged to be of no significance to the safety-related structures. As the structures have been in place for nearly 20 years, the potential for future settlement is negligible.
l Offshore Intake Structure The offshore intake structure is located approximately 1200 feet offshore where the depth of the water is approximately 30 feet. The bottom of the intake structure is approximately 12 feet below the 4
lake bottom (till). A two-foot thick sand bedding was provided and the excavation was backfilled with t.he excavated soil (till) except the upper two feet was backfilled with boulder and cobble. The intake structure is a light structure and is founded on till stratum.
There is no data available on either the estimated or measured settlement of this structure.
Underwater inspection by the diver did not reveal any signs of tilt due to excessive differential settlement (Reference 24).
Based on the information available, it is concluded that the past and future settlement of this structure is minimal with no significance to the safe operation of this safety-related structure.
j Liquefaction and Seismic Settlement The postulated safe shutdown earthquake (SSE) ground acceleration for j
BRP is 0.12g.
The glacial till, material beneath the mat foundation is a very stiff (approximately 20 percent clay content) material which is not susceptible to liquefaction. The granular material (8 feet thick) occurring above the till is in a dense state. The water l
table is in the vicinity of the top of the till stratum so this granular material is not susceptible to liquefaction because it is not saturated.
Seismic induced settlement of t.he till or dense granular material would be negligible.
The intake structure is founded in the till material which is not susceptible to liquefaction. The two foot thick sand bedding under the intake structure might. liquefy and the consequences would be seismically induced settlement of negligible magnitude with no significance to its safe operation, i-,G i
2.5-20 M10987-0362A-BX01
(~N i
b 2.5.4.2 Settlement of Buried Equipment Buried Fire Main Piping System (BFMPS) and Electrical Cables i
Fire main piping system and electrical cables within the plant site are buried at a minimum depth of six feet below ground surface. The j
construction details and specifications for these are not all available.
In the absence of knowledge on the backfill material assuming that the insitu granular material from the excavation was used for backfill, j
it is judged that this material is amenable to compaction and a j
modest compactive effort would result in a dense material estimated i
to be in the 70 percent relative density range.
It is the staff's i
opinion that, in the plant area, there would be no settlecient related loss of support for seismic Category I piping and electrical cables I
founded on and in this material under static cunditions.
Offshore Intake Pipe Line The Intake Pipe runs from offshore intake structure to the Screenwell-pumphouse/ diesel generator / discharge building. This is a 60-inch inside diameter and 6-inch thick wall reinforced concrete pipe buried in the lake bottom to a total length of 1450 feet, in 16.5 foot sections connected with gasketed joints. The pipe is laid in till material (excavation 12 to 16 feet below bottom of lake bed) on 18-inch thick sand bed. The excavation is backfilled with sand up to g
one foot above the pipe and with gravel and cobble of six inch size up to the lake bottom. The sand was placed under water by a tremie.
There was no compaction control in the specifications. The sand (amenable to compaction) has been subjected to some compaction effort when gravel and cobble stones were dumped on top of the sand.
It is the staff's opinion that this material is in tbs 50 to 60 percent relative density range. The staff is also of f he opinion that there would be no settlement related loss of support for this pipe (founded on a 18-inch thick bedding over glacial till) tnder static conditions.
Liquefaction and Seismic Settlement The staterials beneath and surrounding the buried Fire Main Piping Systems arid Electrical Cables are not susceptible to liquefaction (see 2.5.4.1 above). Also, the seismic (SSE) induced settlement of the till or dense granular material would be negligible.
The till beneath the buried offshore intake pipe is not susceptible to liquefaction. The sand bedding under the intake pipe might
- liquefy, If it did, the pipe would not be affected because:
a) the pore water would escape to the overlying gravel fill.
b) a very slight settleinent (a few hundredths of an inch) would occur.
2.5-21 MIO987-0362A-BX01 1
i
,m Hence liquefaction is not a safety problem and also the seismic (SSE) m-induced settlement would be negligible.
2.5.4.3 Evaluation Summary Conclusions (for Section 2.5.4 above)
Based on review of the CPCo Safety Analysis Report (Reference 25) and information obtained during the site visit, the NRC staff concurs j
i with the licensee's conclusions that'
-l 1.
All the seismic Category I structures are founded on competent i
till material and do not possess any potential for future settlement as the settlement was essentially complete soon after construction.
i Any future seismic induced settlement should be minimal and will not pose a safety problem.
2.
The material beneath and around the seismic Category I structures are not likely to liquefy under postulated SSE with a ground acceleration of 0.12g.
The sand bedding under the offshore structures may liquefy and this would result in a seismic induced settlement of negligible magnitude. This would not be a safety cencern.
3.
Settlement of seismic Category I foundations and buried equipment is not a safety problem at the Big Rock Point Nuclear Power p
Plant.
(
2.5.5 STABILITY OF SLOPES Consumers Power Company and the NRC evaluated Systematic Evaluation Program Topic II-4.D, Stability of Slopes, and determined that there are no significant natural or man made slopes on this site whose failure would affect either the safety of the plant or the attaining of safe shutdown of the plant.
Evaluation Conclusion (Reference 26) l The NRC staff concludes that slopes stability is not a radiological safety concern at the Big Rock Point site.
2.5.6 EMBANDfENTS AND DAMS As described in Sections 2.4 and 2.5.4 of this report, there are no
[
significant embankments or slopes and no dams in the site vicinity.
The Systematic Evaluation Program Topic II-4.E Dam Integrity, was.
determined te be "not applicable" to Big Rock Point as documented in the NRC letter dated April 16, 1979 and confirmed by CPCo in the June 22, 1979 response.
l 1
0 l
2.5-22 MIO987-0362A-BX01
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2.5-23 MIO987-0362A-BX01
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.(L CHAPTER 2 REFERENCES
- 1. USNRC letter dated June 6, 1980, SEP Topics II-1.A II-1.B. and II-1.C (Big Rock Point)
- 2. Site Emergency Plan, Big Rock Point Plant, Docket No. 50-155 j
- 3. County and City Data Book 1983, 10th Edition, U.S. Department of Commerce, Bureau of Census.
- 4. HMM Document No.83-600, February 1984, Evacuation Time Estimates for Areas Near the Big Rock Point Nucicar Power Plant.
- 5. U.S. Department of Commerce Bureau of Census Document PC 80-1-A24 Michigan Number of Inhabitants.
- 6. Population Characteristics of Northwest Michigan Counties, Developed by Nancy Haywood, Director, Data Research Center, Incorporated. Traverse City, Michigan, June 1980.
- 7. USNRC Ictter dated May 13, 1981, SEP Topic II-1.C, Potential Hazards Due to Nearby Industrial, Transportation and Military Facilities (Big Rock Point and Palisades).
g--)
- 8. USNRC Atomic Safety and Licensing Board Initial Decision (on all remaining
( j issues) Docket No. 50-155-OLA, (ASLBP No. 79-432-11LA), Served August 29, 1984, IV 0'Neill Contention IID - Risks from Aircraft.
- 9. USNRC letter dated December 17, 1980, SEP Topic II-2.A Severe Weather Phenomena.
- 10. CPCo letter dated March 9, 1981, SEP Topic.II-2.A Severe Weather Phenomena.
- 11. USNRC letter dated August 3, 1981, SEP Topic Il-2.A, Severe Weather Phenomena.
- 12. CPCo letter dated March 1, 1982, SEP Topic II-2.A - Severe Weather Phenomena; III Wind and Tornado Loading; and III-4.A - Tornado Missiles.
- 13. CPCo letter dated April 6, 1982, SEP Topic II-2.C, Atmospheric Transport and Diffusion Characteristics For Accident Analysis.
- 14. USNRC letter dated October 26, 1982, SEP Topic II-2.C, Atmospheric Transport and Diffusion Characteristics for Accident Analysis.
- 15. USNRC letter dated October 26, 1982, SEP Hydrology Topics II-3.A II-3.B, II-3.B.1, II-3.C and III-3.B.
- 16. CPCo letter dated June 23, 1983, SEP Topics II-3. A Hydrologic Description; II-3.B Flooding Potential and Protection Requirements; II-3.B.1 Capability of Operating Plant to Cope With Design Basis Floods; 11-3.C Safety Related O~
Water Supply (Ultimate Heat Sink); III-3.A Effects of High Water Levels on Structures - Response to Safety Evaluation Reports.
2.5-24 HIO987-0362A-BX01
,i i
- 17. NRC letter dated December 2, 1982, SEP Topic III-3.A, Effects of High Water on Structures.
- 18. NRC letter dated March 22, 1984, SEP Hydrology Issues.
- 19. CPCo letter dated February 2, 1984, Integrated Assessment of Open Issues and Completion Dates for Issue Resolution.
I
- 20. NRC letter dated October 12, 1982 SEP Review Topics II-4, Geology and Seismology and II-4.B Proximity of Capable Tectonic Structures in Plant Vicinity.
- 21. Integrated Plant Safety Assessment - Systematic Evaluation Program, NUREG-0828, Final Report, May 1984.
- 22. NRC letter dated July 20, 1982, SEP Safety Topic II-4.F Settlement of l
Foundations and Buried Equipment.
- 23. Seismic Safety Margin Evaluation Report, D'Appolonia Consulting Engineers, Inc. (D'Appolonia), Project 78-435 Dec 80, August 81, Revision 1.
- 24. CPCo letter dated December 21, 1981, SEP Topic III-3.C. Inservice Inspection of Water Control Structures.
- 25. CPCo letter dated October 19, 1981, SEP Topic II-4.F, Settlement of 7-~)j Foundations and Buried Equipment.
i s
- 26. NRC letter dated July 6, 1982, SEP Topic II-4.D Stability of Slopes.
- 27. CPCo letter dated Novembet 21, 1985, Integrated Plan Issue 014 (SEP Topic III-6) Seismic Weak Link Analysis Update.
- 28. CPCo letter dated October 10, 1980, Response to Staff letter dated August 4, 1980, Proposed Seismic Evaluation Program and Basis for Continued Interim Operation.
- 29. NRC letter dated June 30, 1982, Assessment of Possible Soil Amplification at Big Rock Point Site.
- 30. Derivation of Site-Specific Seismic Floor Response Spectra, Seismic Safety Margin Evaluation, D'Appolonia Project No.78-435, August 1983.
d 2.5-25 MIO987-0362A-BX01
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