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9 UNITED STATES g, g,,g NUCLEAR REGULATORY COMMISSION
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%,,',1 30i 13 h34 MEMORANDUM FOR:
Thomas M. Novak, Assistant Director for Licensing, DL FROM:
William V. Johnston, Assistant Director Materials, Chemical & Environmental Technology, DE
SUBJECT:
HYDROLOGIC ENGINEERING INPUT TO DRAFT SAFETY EVALUATION REPORT FOR V0GTLE ELECTRIC GENERATING PLANT Plant Name:
Vogtle Electric Generating Plant Docket Numbers:
50-424/425 Licensing Stage:
OL Requested Completion Date:
October 1, 1984 Licensing Project Manager:
M. Miller Attached is the Hydrologic Engineering Draft Safety Evaluation Report for Vogtle Electric Generating Plant (VEGP).
This evaluation has identified the
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following unresolved issues:
t 1.
Section 2.4.2.2 Effects of Local Intense Precipitation - site drainage and roof drainage of safety-related buildings.
s 2.
Section 2.4.10 Flooding Protection Requirements - since site drainage is open, it is unknown if flood protection will be required in this area.
3.
Section 2.4.11 Cooling Water Supply - adequacy of UHS cooling tower performance is under staff review.
4.
Section 2.4.12 Groundwater - Design basis for hydrostatic loading.
This review was performed by G. Staley of the Hydrologic Engineering Section phone X28003.
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> p William V. Johnston, Assistant Director Materials, Chemical & Environmental Technology Division of Engineering
Attachment:
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4 Thomas M. Novak.
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E. Adensam R. Ballard R. Jachowski J. Wermeil L. Heller C. Chen J. Kane C. Nichols G. Staley
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Vogtle Electric Generating Station Docket No. 50-424 1
Draft Hydrologic Engineering Safety Evaluation 2.4 HYOROLOGIC ENGINEERING 2.4.1 HYDROLOGIC DESCRIPTION t
.2.4.1.1 Introduction l
The staff has reviewed the hydrologic engineering aspects of the applicant's I
design, design criteria and design basis of safety-related facilities for Vogtle Electric Generating Plant (VEGP).
The acceptance criteria used as
.a basis for our evaluations are set forth in the Standard Review Plan (SRP)
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NUREG-0800 in Sections 2.4-1 through 2.4-14 (Hydrologic Engineering).
These acceptance criteria include the applicable General Design Criteria (10 CFR 4
50, Appendix A), Reactor Site Criteria (10 CFR 100) and Standards for Protection Against Radiation (10 CFR 20, Appendix B, Table II).
Guidelines 1 fm for implementation of the requirements of the acceptance criteria are Y'
providad in Regulatory Guides, ANSI standards, and Branch Technical Posi-tions identified in Sections 2.4-1 through 2.4-14 of the SRP.
Conformance to the acceptance criteria provides the bases for concluding that the site i
and facilities meet the requirements of Parts 20, 50 and 100 of 10 CFR with respect to hydrologic engineering.
2.4.1.2 Site and Facilities The site of VEGP which encompasses an approximtte area of 3169 acres, is l
owned by Georgia Power Company.
The plant is located about 26 air miles j
south-southeast of Augusta, Georgia, along the west bank of the Savannah River, and 15 air miles east-northeast of Waynesboro, Georgia, in the eastern sector of Burke County, Georgia, at Savannah River mile 151.1.
The drainage area above the plant site is about 8015 sq. mi. including the Beaverdam Creek area (about 35 sc. H ).
The topography of the site is shown on Figure 2.~4-1.
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' The plant is on high ground with the entrance to the power block buildings at grade el 220 ft msl, approximately 140 ft above minimum river level, and about 80 ft above probable maximum flood (PMF) level. The PMF level is based on all-season probable maximum precipitation (PMP) of Hydrometerological Report (HMR)51(1)andHMR 52(1979 version)(2) by the National Weather Service. The grade elevation at the river intake structure is approximately 125 ft ms1.-
2.4.1.3 Hydrosphere The VEGP site is located adjacent to the Savannah River about 50 river miles below Augusta, Georgia. At a minimum flow of 5800 ft3/s, the river at this location is about 340 ft wide and from 9 to 13 ft deep and has an average velocity of about 2 mph. The two principal headwater streams of the Savannah River are the Seneca and Tugaloo Rivers, which join near Hartwell, Georgia.
From this point, the Savannah' River flows about 300 miles south-southeasterly to discharge into the Atlantic Ocean near Savannah, Georgia.
Its major downstream tributaries include the Broad River in Georgia, the two Little Rivers in Georgia and South Carolina, and Brier Creek in Georgia. The topography of the basin varies from el 5500 ft at the headwaters of the Tallulah River to about 1000 ft in the rolling and hilly Piedmont province, descending to around 200 ft at Augusta, Georgia, and from there, gently rolling to the nearby Coastal province from Augusta to the Atlantic Ocean.
Rainfall is generally abundant and is about 80 in, annually. Snow cover is rare except'in the mountains. Runoff average is about 15 in, annually for the entire drainage area, while runoff at Augusta, Georgia, averages about 19 in. Total stream flow varies considerably from year to year. Streams in the basin typically have high flows in the winter and early spring. During the sumer, flows diminish and remain low through autumn. Two upstream reservoirs, Clark Hill and Hartwell, along with certain channel improvements, ens.ure minimum water requirements. River regulation has increased the minimum daily flow from a record of 1105 ft3/s before construction of the dams to 6100 ft3/s after their construction.(3)
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. As shown in Figure 2.4-2 the Savannah River Basin is wider at upper. reaches and has about uniform width from Hartwell Dam to Clark Hill Dam.
From Clark Hill Dam to Augusta the width gradually narrows.
Below Augusta the basin continues to narrow to the Atlantic Ocean.
There are three major Corps of Engineers dams in the Savannah River Basin; namely, Hartwell, Richard B. Russell, and Clark Hill.
The thrse reservoirs have a total storage capacity of about 5,660,000 acre-feet of which 683,000 acre-feet are reserved for flood control.
In addition to flood control, the reservoirs also provide water for hydroelectric power generation and low flow augmentation.
The reservoirs also trap sediment which reduces dredging costs in the downstream navigable waterways and harbors.
Additional information on these and other dams in the basin is provided in Table 2.4.1.
There are two domestic water users of surface water (the Savannah River) downstream of the. plant.
These users are Beaufort / Jasper County, 112 river miles downstream, and the Cherokee Hill (Port Wentworth) water treatment plant, 122 river miles downstream.
Section 2.4.13 discusses the conse-quences of effluent releases to surface waters.
The staff has reviewed the material presented in the FSAR and drawings and photographs obtained during the site visit and conclude that the general hydrologic description of the site meets the applicable requirements of 10 CFR Part 50, Appendix A, GDC-2 and the acceptance criteria in SRP 2.4.1.
2.4.2 FLOODS 2.4.2.1 Flood History Th'e maximum flood on the Savannah River occurred in 1796.
The peak discharge at Augusta, Gecrgia was estimated to be 360,000 cubic feet per second (cfs).
The applicant estimated that a comparable flood would produce a water surface
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TABLE 2.4.1
-(SHEET 1 OF 2)
WATER CONTROL STRUCTURES SAVANNAH RIVER BASIN Concrete St rise ttere
( Powe r-Spill-Fa rth. hotisc Crest way No rma l Top Spill-Nonover-el Crest Pool Normal of Selsmic.
way Drainage Dike River Storage Area Length flow Wall)
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No. of Length el Head Das Design Design pp_ ants Nne_r HXe_ f acre-f t)
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fft1 m_31L ' frJtiel. - _[.[LL ELp1D _ ELL 3.L,
Criteria M t.erj.J!
13.1 152.6 7508 tiew Savannah Biterr 187.7 Lock and Das Corps of Inuancers 29 187 Stevens Creek 209.7 s.c. E lec. ar e
c.i s Clark Ilill 222.7
- 2. 51'O. 00tl 6144 3398 1186 300 23 1096 335 136 351 Yes PHI Cos ps or 0 el 335
[ngineers Richaed G. Rtissell 26fl.2 6n0.000 2900 2 68:0 1888e 436 10 590 475 175
~495 Yes PHI Corps or e el 415*
Inqincers sta rtwe l 8 290.0 2.549.600 2088 15.952 1332.
630 12 568 660 185 679 Yes PHI corps or 0 el 660
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,744.2 70.25 757 yonah 340.0 10.200 e 4 F0 ccorgia Power Co.
el 144.2 493 885 8'F8 357 891.5 144
.905 lugaloo 343.1 43.20n 0 464 coorgia Power Co.
el 891.5
' 1JO 1493 7'f8 316 1500 603.4 1514 -
1alltilah falls 346.1 2460 e 186 Cenrgia Power Co.
eI 1500 Mathis 353.4 31.400 0 151 370 312 1681.25 8.5'f8 285 1689.6 189.6 17081 Ceargia Power Co.
el 1689.6 350 1752.5 open 140 1752.5 62.2 1765 Nacoachee 362.1 8200 0 136 ceorgia Power Co.
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Concre te Structure (Power Spill-Earth slouse crest way Normal Top Spill-Drainage Dike Monove r-el Crest Pool floreal of
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30 0. of, Length el Head Das Design Design !
pre and Owner Mile lagfe-ft) leial_ f ftl.
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Criteria Critgrla
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845.5 1860 6.5'f8 ccorgia Power Co.
el 1866.6 197 1866.6 114.1 1873 i
krowee 341.01 940.000 439 3500 765 4
176 t00 140
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keowee keowee 1100 310
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Jocassee 357.G! 1.100.000 148 1800 Duke Power Co.
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4 elevation at the site of 116 feet msl. The maximum flood during the period since records were maintained (1883) at Augusta was 350,000 cfs and occurred on October 3, 1929. These floods occurred prior to construction of several upstream dams. Flood flows are now regulated by Hartwell, Richard B. Russell and Clark Hill Reservoirs as well as by upstream hydropower plants (including two associated with the three-unit Oconee Nuclear Power Plant).
2.4.2.2 Effects of Local Intense Precipitation The staff has reviewed the FSAR and determined that there is not sufficient information available to enable us to reach a conclusion on the effects of local intense precipitation. The applicant has been asked to provide additional information and detailed analysis of the roof drainage system including roof ponding levels on safety-related structures. The applicant a-was also asked to provide additional information and detailed analysis of
E'g the site drainage system and its ability to dispose of local severe precipi-tation up to and including the local PMP. The applicant was asked to consider the most recent PMP guidance available on rainfall depth-duration relations.
Until the additional information and analysis are available, the staff cannot conclude that the plant meets the requirements of GDC 2 with respect to the effect of local intense precipitation on safety-related structures.
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. i% A 2.4.3 PROBABLE MAXIMUM FLOOD (PMF) ON STREAMS AND RIVERS 1
The applicant has made several estimates fer PMF flow at the VEGP site based on standard hydrologic techniques including PMP based on HMR 51 and 52(1)(2),
streamflownetworksimulationmodels9)anddesignspillwayoutflowfromClark Hill Dam. These PMF discharge estimates range from 540,000 to 895,000 cfs at the VEGP site.
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A stage discharge relationsilip was deiefoped by the applicant for the VEGP-site (Figure 2.4-3), by using a computar program obtained from the Corps of Engineers,designatedHECi2"WaterSurfaceProfiles."(6)
In this study 29 cross-sections were taken from United States Geological Survey (USGS) topo-graphical maps. Three of these sections at the VEGP site were field checked and ccmpared with the USGS maps.
In order to obtain approp'riate values of n(coefficientofroughness),thefloodsof 1929, 1940, and 1948 were run to 9%
compare high-water marksiwith computer results. The staff has reviewed the g
procedures and parameters used by the applicant and concur with the resultant stage-discharge rating curve as shown in Figure 2.4-3.
Using the maximum PMF discharge of 895,000 cfs and the rating curve in Figure 2.4-3, the maximum PMF elevation, at the VEGP site would be about 137.0 ft msl. The applicant estimated that wave runup from coincident winds could amount to an additiccal 25 feet. T,he applicant's wave runup value may be overestimated by as much as 10 feet, but it is irrelevant since the combined wave runup and base flood level (162.0 ft msl) is well below the plant grade elevation of 220 ft msl. This site is' considered a " Dry Site" in accordance with the definition provided in Regulatory Guide 1.102.
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-s-The staff made an additional independent analyses using the conservative generalized PMF from Appendix B of Regulatory Guide 1.59.
These generalized curves indicate a PMF peak discharge of 1,000,000 cfs for the 8015 square mile drainage area above the VEGP site.
Using the rating curve in Figure 2.4-3, this discharge corresponds to a peak flood elevation of about 140 ft ms1.
Based on the applicant and staff analyses we conclude.that the plant meets the requirement of 10 CFR Part 50, Appendix A, GDC-2 and fulfills the
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5 acceptance criteria specified in SRP 2.4.3 with respect to flood potential from the Savannah River.
2.4.4 POTENTIAL DAM FAILURES The major dams upstream of the VEGP site are designed such that most seismic events would notzcause failure of these structures.
However, domino-type failure of the upstream dams is assumed to evaluate the effect of the flood erm wave at the plant site.
All safety related structures and equipment are 3
above the dam failure and coincident' wave runup elevation of 168 ft ms1.
2.4.4.1 Dam Failure Permutations There are 13 dams on the Savannah River and its tributaries above the VEGP site. The Hartwell and Clark Hill Dams are major dams immediately upstream of the plant site.
Between Clark Hill and Hartwell Dams another major dam, Richard B. Russell, is under construction and is scheduled for completion in 1984.
The existing and proposed dams are shown in Figure 2.4-2.
The VEGP site is considered a dry site.
Even if Clark Hill Dam fails due to a seismic event coincident with probable maximum flooding, the flood wave dissipates substantially before it reaches the plant site due to valley storage.
In that event the intake structure will be flooded.
Since the intake structure is not a safety-related facility, its flooding will not affect the' sa"ety of the plant.
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The applicant has also investigated the effect of other potential dam P
failures above VEGP and the resultant Savannah River water surface profiles to determine the basic assumptions for the worst possible dam failure to affect VEGP.
The study indicated that the worst reasonable failure that can be postulated.would be the failure of Jocassee Dam as a result of an earth-quake during a standard project flood (SPF) and the chain reaction that would follow.
A seismic failure of Jocassee Dam is not reasonably possible, since it h'as oeen designed as stated in the PSAR for the Oconee project (7) to include earthquake forces (design basis earthquake - 0.1 g).
However, it is more conservative to postulate this failure in determining the maximum water 7
level at VEGP.
The applicant analyzed such a failure scenario where Jocassee Dam was assumed to fail during a Standard Project Flood (SPF).
The floodwave from this breach would overtop and fail Keowee Dam 15 miles downstream.
The outflow from the assumed Keowee Dam failure would overtop and fail the earth section.of Hartwell Dam 51 miles downstream.
The surge wave from the assumed Hartwell Dam failure would overtop the Richard B. Russell Dam, 60 miles downstream by about 9 feet.
The assumed failure of the r :hard B. Russell Dam would produce a floodwave that would overtop (by (sout 6 feet) and fail the Clark Hill Dam, 38 miles downstream.
The applicant assumed instantaneous removal of Clark Hill Dam which results in a peak outflow discharge of 2,400,000 ft3/sec.
The outflow hydrograph from the failure of Clark Hill Dam was transferred undiminished, to New Savannah Bluff Lock and Dam which is down river from Augusta, Georgia.
l This hydrograph was then routed past the VEGP site using the unsteady,
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nonuniform flow computer program SOCH(8)
The peak stage and discharge at the VEGP site is 141 ft ms1 and *&OOO ft3/sec, respectively.
The coincident wind wave runup would reach about elevation 168 ft ms1 which is
.well below plant grade at elevation 220 ft ms1.
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The U.S. Army Corps of Engineers (9) also analyzed several multiple dam failure scenarios in order to develop Flood Emergency Plans for the areas downstream of their dams on the Savannah River.
This worst case scenario was the failure of Hartwell, Richard B. Russell and Clark Hill Dams during the Hartwell Spillway Design Flood.
This failure hydrograph was only routed downstream to the New Savannah Bluff Lock and Dam just south of Augusta, Georgia.
The peak stage at the Lock and Dam is about elevation 149 ft ms1 and would be considerably less at the VEGP site, 50 river miles downstream.
Based on our review of the dam failure analyses performed by the applicant and the U.S. Army Corps of Engineers, we conclude that upstream dam failures on the Savannah River will have no affect on safety related facilities at VEGP.
Using the procedures described in SRP Section 2.4.4, we find that the plant meets the requirements of GDC-2 with respect to the hydrologic aspects of dam failures.
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2.4.5 PROBABLE MAXIMUM SURGE AND SEICHE FLOODING This SRP section is not applicable because VEGP is not sited near a large body of water susceptible to surge or seiche flooding.
2.4.6 PROBABLE MAXIMUM TSUNAMI FLOODING This SRP section is not applicable because VEGP is not near a large body of water susceptible to tsunami flooding.
2.4.7 ICE EFFECTS There is no record of ice formation on the lower reaches of the Savannah River.
This observation is further supported by records of river tempera-ture where the minimum observation is generally greater than 5*C.(10)
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Ice jams are unlikely to occur at the VEGP river intake, since Hartwell, Richard B. Russell, and Clark Hill Dams upstream of Augusta will modulate the water temperature.
If surface icing were to occur at VEGP, the design of the river intake and the normal water depth of 24 ft ensure that an ice sheet across the entire river will not interfere with flow of water into the intake.
On the basis of its review of the FSAR, using procedures in SRP Section 2.4.7, the staff concludes that the effect of ice on the intake structure would not adversely effect plant operation and, therefore, the plant meets the require-ments of 10 CFR Part 50, Appendix A, GDC-2, 50.55a and 100 with respect to ice effects.
2.4.8 COOLING WATER CANALS AND RESERVOIRS There is a short canal less than 400 ft long formed by vertical sheet piling walls connecting the river intake structure and the Savannah River. As discussed in Section 2.4.11.5, the river makeup water is the secondary backup source for the nuclear service cooling water tower basins. The river intake structure as well as the intake canal have no safety function. Thus, failure of this river intake canal will not cause a threat to the safety of plant operations. There are no reservoirs at VEGP, A review under the procedures of SRP Section 2.4.8 is not applicable to this plant.
2.4.9 CHANNEL DIVERSIONS The Savannah River near the VEGP site has a relatively straight and stable channel.
It is very unlikely that the river will be diverted from the intake by natural causes. Any possible effect on water supply to the intake from channel changes should come from extremely slow changes, which can be remedied as they occur. Since, as previously stated, the river intake has no safety function, a review using the procedures of SRP Section 2.4.9 is c-not applicable to this plant.
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. 2.4.10 Flooding Protection Requirements As discussed in Sections 2.4.3 and 2.4.4, safety-related structures systems and components are protected from the effects of flooding. The staff concludes that although the intake structure will be flooded during the design basis event, it is not a safety-related structure and that potential flood levels from the Savannah River are well below plant grade level and thus are not a threat to safety-related facilities. With the exception of site drainage (Section 2.4.2.2 " Effects of Local Intense Precipitation"), the requirements of SRP 2.4.10 have been met and provisions for flood, protection are acceptable. The review of site drainage will be completed when the appli-cant furnishes the information requested by the staff.
2.4.11 COOLING WATER SUPPLY sf The ultimate heat sink for VEGP is the nuclear service cooling water (NSCW) towers. Two 100-percent capacity Seismic Category I redundant NSCW towers -
are provided for each generating unit, one tower associated with each train
-of the NSCW system. Each NSCW tower consists of a basin which contains the ultimate heat sink' water and an upper structure in which the NSCW heat loads are transferred to the atmosphere. The applicant states that the combined storage capacity of the two tower basins per unit are designed to meet the intent of the short-term storage requirements without makeup and is in con-formance with Nuclear Regulatory Commission (NRC) Regulatory Guide 1.27.
The staff has several reservations regarding the capabilities of the system, as discussed below.
2.4.11.1 System Description The NSCW towers are circular mechanical draft towers constructed of reinforced concrete. Each tower is subdivided into four individual fan cells. Each tower includes a pumphouse which contains the NSCW pumps, transfer pump, return header, and bypass valves.
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. Each NSCW fan is driven through a right-angle gear reducer by a 100 hp, 1800-rpm motor that is powered from the essential ac buses.
Each fan is 22 ft in diameter with 12 blades and has a capacity of 535,000 ft2/ min.
The NSCW tower basins have an 88-ft inside diameter and are 80 ft 3 in deep at minimum water level.
The minimum capacity of each basin is 6
3.65 x 10 gal of water.
Safety-related transfer pumps are provided in each tower basin to allow water in either basin to be used as makeup for the other basin.
2.4.11.2 System Operation The NSCW pumps take suction from the cooling tower basin as described in subsection 9.2.1.
The water is returned to the cooling tower spray mani-folds, or in the event of low return temperature from the NSCW system, the
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spray manifolds are bypassed and the water is returned directly to the Heat rejection to the environment is affected by direct contact with basin.
the forced airflow, which provides both sensible and evaporative cooling of the NSCW return flow.
Evaporation and drift losses during normal operation are made up from NSCW makeup wells and, if required, from the Savannah River.
The NSCW tower basins and pumps are also designed to ensure adequate pump net positive suction head under all operating modes and at the end of the short-term period prescribed in Regulatory Guide 1.27.
During accident conditions, including a loss-of-coolant accident (LOCA) or a main steam line break accident (MSLBA) inside the containment with loss j
.of offsite power, sources of basin makeup water (non safety-related) are P
presumed lost.
During such conditions, the combined inventory of the 2 NSCW tower basins per generating unit provides a 26.7-day cooling water supply, assuming the worst combination of meteorological conditions and accident heat loads which maximize tower heat load, basin temperature, and evaporative lo'ss es.
Each tower basin contains approximately one-half of the supply, with
' transfer pumps provided to permit the combined storage capacity of the
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4 2 basins to satisfy the 26.7-day short-term requirement of Regulatory Guide 1.27.
The basins are concrete Seismic Category 1 structures located entirely below ground with the normal water level approximately at grade, a basin failure resulting in loss of water inventory is considered highly improbable.
2.4.11.3 System Performance Based on heat loads (FSAR Table 9.2.5.2) on the NSCW coolitg towers during both normal operation and accident conditions and extreme meteorological data from the U.S. Weather Station at Augusta, Georgia, the applicant analyzed several scenarios of UHS operation to determine maximum water use and maximum return water temperature.
The applicant's analyses predict a maximum return water temperature of 92.9 F and maximum water use of 6
3.65 x 10 gallons (equivalent to 26.7 days of operation) for the 30 day performance period specified in Regulatory Guide 1.27.
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The applicant needs to provide a discussion in FSAR Section 9.2.5 regarding the use of the UHS 30-day water supply for fire protection.
This should include a description of when the water in the NSCW cooling tower basins might be used for fire protection and the extenuating circumstances.
Discuss the significance of the impact on the 30-day water supply consider-ing that the makeup sources for the NSCW cooling tower basins is not seismic category I.
FSAR Section 9.2.5.6 is also unclear.
Apparently, the analyses (for water use and temperature) presented in Section 9.2.5 was done for the PSAR and the basins provided a 26.7 day supply without makeup.
Then apparently subsequent to the PSAR ather changes occurred (diesel generator rating, fuel pit loading, " worst 30-day" meteorological data) which reduced the storage capability by 6.2 days or a net availability of 20.5 days.
The applicant next discusses conservatisms that can increase the capacity
~
(2.7 days), but these are added onto the 26.7 day value rather than the 20.5 day corrected value to give an estimated capacity of 29.4 days (25.7 + 2.7) rather than 23.2 days (20.5 + 2.7).
k-o
. - If the applicant chooses to take credit for the stated conservatisms then the analyses should be re-done incorporating the "conservatisms" with appropriate explanation so that the information can be reviewed.
Additionally, Regulatory Guide 1.27 allows that a cooling water capacity of less than 30 days may be acceptable if it can be demonstrated that replenish-ment or use of an alternate water supply can be effected to assure the continuous capability of the sink to perform its safety functions, taking into account the availability of replenishment equipment and limitatons that may be imposed on " freedom of movement" following an accident or the occurrence of severe natural phenomena.
Thus, the applicant needs to discuss procedures for ensuring replenishment or alternate source of make-up for less than 30-day capacity and continued capability after 30 days.
The staff has not yet completed its independent analyses of the thermal and
]
hydrologic performance of the emergency cooling water supply.
This will have to be completed before the staff can determine whether the plant meets RG 1.27 and GDC 44 with respect to the emergency cooling water system.
2.4.11.4 Plant Requirements During normal plant operation, a flow of 406 gal / min makeup water is required to replace evaporative losses and also losses due to drift and cooling tower blowdown.
During accident conditions, maximum evaporative losses are 1270 gal / min (for 2-train NSCWS operation) immediately after reactor shutdown, decreasing to 340 gal / min after 1 day and 210 gal / min after 30 days.
Tower blowdown is isolated during accident conditions, and therefore, total losses and makeup requirements during accident conditions comprise only evaporation and drift.
However, as discussed in subsection 9.2.5, tower makeup is assumed to be unavailable during the assumed 30-day period subsequent to reactor shutdown under accident conditions concurrent with a loss of offsite power.
The combined storage capacity of the two
~
. NSCWS cooling tower basins provided for each generating unit should be suf-ficient to provide the approximate 30-day inventory to permit safe reactor shutdown and maintenance of the plant in a safe shutdown condition to be in conformance with the short-term requirements of Regulatory Guide 1.27. The adequacy of the basin storage volume is still under staff review.
To provide NSCWS makeup during normal operation and to provide long-term (after 30 days) cooling in conformance with Regulatory Guide 1.27, water from nonsafety-related systems (deep water wells and the Savannah River) is available. Two makeup wells provide the primary makeup to the NCSWS cooling towers for both generating units, with each well equipped with a 2000-gal / min pump. The wells are approximately 2100 ft apart, and each is located approximately 1000 ft and 400 ft, respectively, from the immediate plant site boundary. These wells provide water for the following uses:
[
Fire protection.
Construction demands.
Potable and sanitary uses.
Makeup to the well water storage tank.
Water in the well water storage tank is utilized for utility purposes, for NSCW tower makeup, and for the makeup demineralizer.
The makeup wells have been sited on the basis of extensive investigations on the characteristics of the groundwater at plant site, which show the existence of two distinct aquifers, a shallow water table aquifer and a deep, confined Tuscaloosa aquifer.
Estimated recoverable water quantity in the Tuscaloosa aquifer is approximately 21 billion acre-ft.
In_the event that the well water is not available, river water can also be utilized for NSCW cooling towers makeup. The Savannah River provides the makeup water for the natural draft cooling towers and dilution water for the plart effluent discharge. The Savannah River, bordering the plant site en the east side, is approximately 340 ft wide and 9 to 13 ft deep at the site,
4 with mininum and maximum flows of 5800 ft3/s and 71,700 ft3/s, respectively.
The river temperature, recorded at the Burton's Ferry Bridge from January 1960 through September 1970, ranged from a minimum of 41 F (5 C) to a maximum of 84*F (18.9 C).
Four 22,000 gal / min capacity nonsafety-related river makeup water pumps provide makeup to the natural draft coeling towers.
Provision is also made for these pumps to supply additional dilution water as required for the plant radwaste liquid discharge to the Savannah River.
Piping is provided from the supply header of the river makeup water pumps to the basins of the NSCW cooling towers as a secondary source of makeup water.
The plant makeup-water well system serves as the primary makeup source for the NSCW cooling towers.
1 To ensure adequate river mdkeup water pump suction conditions, the pump
~
- g suction is installed 9 ft 10 in, below the minimum river water surface elevatio'n of 78 ft, in accordance with the requirements specified by the pump supplier.
The large Corps of Engineers dams located on the Savannah River upstream of the site provide a large volume of multipurpose storage that augments low flows in the riv~er.
Minimum river flows should not be less than 5800 cfs which is more than adequate for plant make-up requirements.
The completion of staff review under the providions of SRP Section 2.4.11 is contingent upon the applicant providing clarification of the analyses for 30 day water supply and identification of alternate sources for the period between the basin capacity and 30 days (Section 2.4.11.3) and the staff co.tpl.etion of its independent analysis.
We cannot conclude that the plant meets the requirements of GDC-44 and the criteria of Regulatory Guide 1.27.
Therefore, Section 2.4.11 Cooling Water Supply is a confirma-tory issue.
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16-2.4.12 GROUNDWATER 2.4.12.1 Local Aquifers, Formations, Sources, and Sinks The initial geologic exploration program for VEGP included groundwater field studies which were conducted principally within a 25-mile radius of the site.
The groundwater investigative program included pumping tests, permeability testing, well canvassing, chemical analyses, and observation well installation and monitoring.
Additional hydrogeologic data were also acquired during the Millett fault study of 1982 (reference 11).
These data are the basis for establishing groundwater conditions within the 25-mile 4
I radius.
In the vicinity of the main plant facilities at the VEGP site;there are two distinct aquifers.
Referring to Figure 2.4-4, above the Blue Bluff Marl j p,.
Member'of.the Lisbon Formation.(Tertiary System), there is a perched (water table) aquifer.
In the vicinity of the river intake structure there is also' a water table aquifer in the alluvium adjacent to the Savannah River.
Below the Blue Bluff Marl Member of the Lisbon Formation there is a confined or artesian aquifer that includes a Tertiary aquifer in the Lisbon Formation and a Cretaceous aquifer in the Tuscaloosa Formation.
These two aquifers are separated by an aquitard consisting of the Huber and E11enton Formations.
The aquitard permits hydraulic contact between the Tertiary and Cretaceous aquifers.
2.4.12.1.1 Tertiary and Quaternary Water Table Aquifers
- The marl aquiclude is overlain at VEGP and throughout much of the 25-mile study area by the Barnwell Group (late Eocene) which, in turn, is overlain by the Hawthorne Formation (early Miocene).
Both formations are extensively exposed since erosion has removed much of the Hawthorne unit.
Pleistocene I
al'1uvial and terrace deposits are also present as are Halocene flood plain deposits parallel to the Savannah River.
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. In the general vicinity of VEGP, the basal unit of the Barnwell Group is the Utley Limestone member of the Clinchfield formation (Figure 2.4-4).
This is a fossiliferous and cavernous limestone unit which is capable of transmitting groundwater.
However, the unit rarely exceeds a few tens of feet in thickness, and it is of limited areal extent.
The remaining sedimentary units overlying the marl and the Utley limestone consist of unconsolidated clays, silts, and sands, which contain ground-water'under water table conditions.
Data from packer and permeameter tests performed during exploration and plant construction indicate that both
-lateral and vertical permeability of these sediments varies considerably.
This variation is attributed mainly to the highly variable quantities of clay distributed throughout the aquifer.
1 Hydrogeologic characteristics of the water table aquifer are not well known due to lack of development.
No studies were made for the VEGP program f
T as there was never any intention of using water from this aquifer for either construction or plant operation.
Water level data have been gathered during well canvassing programs, but aquifer characteristics such as trans-missivities and storage coefficients are not known.
The canvas data show that the overwhelming majority of wells open to the water table aquifers are low yield, domestic walls for which quantitative data are very sparse.
Recharge to the water table aquifer is almost exclusively by infiltration of direct precipitation.
The presence of porous surface sands and the moderate topographic relief in the site area indicate that there is no significant storm runoff; hence, virtually all precipitation infiltrates the ground.
Lateral recharge from adjacent areas is insignificant because the plant area is situated on an interfluvial high; i.e., it is isolated by drainage channels which have down cut to or near the marl aquiclude and
~
act as interceptor drains to potential recharge sources moving laterally tokard the interfluve.
Lateral recharge from the Savannah River would be possible only in the case of a very severe flood, one that is capable of raising the river level some 30 ft or more.
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. 2.4.12.1.2 Cretaceous and Tertiary Groundwater Systems The Cretaceous groundwater system is represented in the 25-mile study area by the Tuscaloosa formation.
This formation which lies about 400 feet below plant grade is approximately 700 ft thick near the VEGP and appears to be of equal or greater thickness in South Carolina in the Millett fault study area.
It consists primarily of cross-bedded sands and gravels with subordinate beds of silt, clay, and kaolin (Figure 2.4-4).
It is a highly transmissive aquifer system.
Recharge to the Cretaceous aquifer is primarily from infiltration of rainfall where the formation is exposed north of VEGP.
In the same general area, the Tertiary groundwater system is also exposed and off-laps the j,, Cretaceous system.
In this area, the Cretaceous and Tertiary systems are in hydraulic contact and the groundwater is under water table conditions.
p After the water infiltrates the sediments, it migrates downdip in a south by southeast " direction.
At some distance downdip from the recharge area, groundwater in' the Cretaceous sediments becomes confined beneath the relatively impermeable clays and silts of the Huber and E11enton Formation (Paleocene).
The exact point at which these two units become an effective aquiclude has not yet been determined, but it probably does not occur until it progresses a few miles south of VEGP.
Groundwater in the Tertiary system also migrates downdip in the same general direction, and within 4 few miles of the recharge / outcrop area becomes confined beneath the Blue Bluff marl member of the Lisbon Formation.
This means that the Cretaceous and Tertiary systems are both under artesian conditions and are in hydraulic contact for several miles updip of VEGP and become separate and discrete hydrogeologic units somewhere between the VEGP and Sardis to the south.
In this zone, two significant changes take place.
First, the Blue Bluff marl undergoes a facies change to permeable limestone.
Combined with the moderately permeable underlying sands and permeable overlying sediments of'the Lisbon-equivalent formations, the sequence becomes the principal artesian aquifer.
Clays and fine grained sediments of the Barnwell and younger formations. provide the confinement to produce artesian conditions.
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. The second change occurs in the permeability of the Ellenton and Huber
' Formations.
Permeability decreases to such a level as to confine the Cretaceous system under a separatt hydrogeologic regimen, which differs from the Tertiary system.
The piezometric levels of the two systems are different, as are their permeabilities.
At the VEGP site, the Tertiary groundwater system is represented by two members of the Lisbon Formation (Figure 2.4-4).
The lower member con-sists of fluvial sands and sandy clays for which formal stratigraphic nomenclature has not yet been established.
These sediments are moderately permeable, as shown by field permeability tests for the river facilities and by the operation of the VEGP potable water supply well, which is completed in the upper 25 ft of this member.
Total thickness at the site is approximately 100 ft.
The source of cooling system makeup water at VEGP
.is' wells producing from these Cretaceous / Tertiary aquifers.
Pumping tests conducted for makeup water wells MU-1 and MU-2(a) indicated transmissivities g
b in the range of 110,000 to 230,000 gal /d/ft and storage coefficients ranging
-5
~4 from 2.1 x 10 to 6.6 x 10 for the combined aquifer system.
The second member of the Lisbon Formation at the site is the Blue Bluff marl member, which consists of semiconsolidated glauconitic marl with subordinate lenses of dense, well-indurated, well-cemented limestone.
The marl layer overlies the unnamed sands member and is approximately 70 ft thick.
The permeability of the marl layer is extremely low, and it is classified as an aquaclude.
It effectively confines the unnamed sands to produce artesian a.
Makeup water well MU-2 is being relocated.
The new well was scheduled to be completed by June 1984 at which time the old well will be
~
abandoned.
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. conditions at the site.
Downdip from VEGP, the marl grades to limestone (unnamed) and becomes a member unit of the progressively thickening Tertiary aquifer system that is more commonly known as the principal drtesian aquifer.
The Huber Formation (Paleocene), which separates the two aquifers and confines the Cretaceous system, is present at VEGP, but, based on its lithology, it probably is not an effective aquiclude because the two aquifer systems are in hydraulic contact in the general vicinity of the plant site.
Downdip from VEGP, the clay content of the Huber Formation increases and it does become an effective aquiclude, as indicated by two distinct piezometric levels that were established by the Millett fault study.(11)
The E11enton Formation (Paleocene), which underlies the Huber Formation,
.( x was not recognized at VEGP, but was identified in the exploratory borings for the Millett fault study.
It, therefore, either pinches out between VEGP and Girard (located 7 miles south of the site) or it thins to such a degree that it cannot be mapped at VEGP.
The Ellenton unit consists mainly of carbonaceous clays, which augment the confining properties of the overlying Huber Formation.
To summarize, the Tertiary aquifer system overlies and off-laps the Cretaceous system in its outcrop areas north of VEGP.
Groundwater is under water table conditions in both aquifers in this area.
Progressing downdip, the two systems become separated stratigraphically (but not hydraulically) by the Huber Formation, which pinches out several miles north of VEGP.
The two systems also become confined beneath the Blue Bluff marl member of the Lisbon Formation.
These conditions prevail to an unidentified point between VEGP and Girard.
In this area, hydraulic separation occurs as the Ellenton Formation begins and, combined with the Huber formation, confines the Cretaceous system under artesian conditions.
Still further downdip, the marl grades to limestone and combines with both
,.J,.
underlying and overlying permeable Tertiary units to become the principal artesian aquifer.
Confinement is provided for this system by fine grained silts and clays in the overlying Barnwell Group and younger Tertiary sediments.
2.4.12.1.3. Pre-Cretaceous Groundwater Systems None of the exploratory borings for the VEGP penetrated the crystall'ine basemat rocks.
There are no plans to use this system as a source of water for VEGP and thus it is not discussed here.
2.4.12.2 Hydrogeologic Properties of Subsurface Materials 2.4.12.2.1 Properties of the Lisbon Formation and Alluvium i
The Lisbon Formation at the VEGP consists of an unnamed sands member
- 7 x,
overlain by the Blue Bluff marl member (Figure 2.4-4).
The sands member is in hydraulic contact with the Cretaceous system, hence the hydrogeologic properties determined from the pumping tests for MU-1 and MU-2 include influences these sands contribute to the overall system.
Permeability tests were performed in the unnamed sands during early site investigations and again as part of the field investigations related to construction of the river facilities.
All of the permeability values obtained during the river facilities investigation are summarized on l
Table 2.4-2.
These latter tests, which were performed in the upper 20 ft of the sands, showed a permeability range of 60 to 340 ft/ year.
This range of relatively l
low values are indicative of the varying amounts of silt and possibly clay in the unit at the site.
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TABLE
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PERMEABILITY TEST. RESULTS - RIVER FACILITIES AREA Cround Depth Elevation.
Test Permeability"U L oca t i on'*8 Elevation fft1 frtl fft1 Method f f t/vea rt cm/s x 10 Ma lg ria l Alluvial silts / clays P-4A 94.6 0 - 7.5 94.6 - 87.1 E-19 130 1.3' P-6A 90.5 0 - 4.0 90.5 - 86.5 E-19 2(0 2.5 E-18""3 36,000 348 Alluvial sands P-68 91.8 10.0 - 20.0 81.8 - 71.8-E-18"3 21,000 203 P-6C 92.1 20.0 - 30.0 72.1 - 62.1-I P-60 91.7 30.0 - 40.0 61.7 - 51.7 E-18 27,000 260 Wea the red ma rt P-1 102.1 6.0 - 11.0 96.1 - 91.1_
E-18 0
102.6 0 - 6.0 102.6 - 96.6 E-19 15 0.15 (l.isbon formation)
P-1A P-1 107.8 7.0 - 17.0 100.8 - 90.8 E-18 O'
P-3A 107.9 0 - 6.5 107.9 -101.4 E-19 25 0.24 Ha ri member P-1 102.1 11.0 - 31.0 91.1 - 71.1 E-18 0
8 (Lisbon formation)
P-2 102.2 5.0 - 30.0 97.2 - 77.2 E-18 50 *:
0.5 P-3 107.8 17.0 - 37.0 90.8 - 70.8 E-18 0
P-5 96.3 12.0 - 27.0. 84.3 - 69.3 E-18 608 0.06 Lower sand member P-1 102.1 33.0 - 48.0 69.1 - 54.1 E-18 240 2.3 (Lisbon formation)
P-2 102.2 30.0 - 50.0 72.2
.52.2 E-18 190 1.8 P-3 107.8 40.0 - 54.6 67.8 - 53.3 E-18 250 2.4 P-4 93.7.
21.0 - 36.0 72.7 - 57.7 E-16 60 0.6 P-5 96.3 29.0 - 54.0 67.3 - 52.3 E-18 340 3.3
- i. liole locations are shown on figure 2.5.1-11.
b.
Permeability values shown are rounded off, c.
Modirled E-18; cemented casing above test Inte rva l,
d.
Possible hydro-fracturing of test material.
c.
Possible packer leak.
c t-g, e
(
. The river facilities investigation also included permeability tests in the marl member. These tests indicated that the marl is essentially imperme-able. Results of the tests are summarized in Table 2.4-2.
Further indications of the extremely low permeability of the marl were also obtained during the tests performed to determine its effectiveness as an aquiclude. At exploratory hole 42, a series of observation wells located at various depths and designated 42A, B, C, D, and E provide a measure of the effectiveness of the marl as an aquiclude.
Head differential between two wells (42A and 428) which are located just above and just below the marl is more than 50 ft. This difference is consistent throughout the area covered by observations wells.
Exploratory hole 42 was abandoned during plant construction. This and all other holes not completed as observation wells and open to the confined aquifer were sealed with grout.
The marked difference in water levels indicates a large contrast in
/
permeability between the aquifers and the marl. To bring about such a marked difference in piezametric levels, the barrier must be extensive and without significant through-going openings such as fractures or solution cavities.
The continuity of the marl is verified over a large area by numerous explora-tory holes drilled through it. None of the borings encountered highly fractured zones nor was there evidence of leaching and removal of calcareous material.
1 Permeability tests were performed in the alluvial materials along the Savannah River as part of the river facilities investigation.
To a depth of 10 ft, these deposits show a permeability range of 130 to 260 ft/ year.
Tests from a depth of 10 t'o 40 ft show a permeability range of 21,000 to 36,000 ft/ year. The wide difference between the upper 10 ft and the lower 30 ft is attributed mainly to normal gradation for stream deposition; i.e., coarser (and more permeable) grains settle out first while finer (and less permeable) grains settle out last.
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. The range of values shown on' table 2.4-3 compare favorably with values for similar types of material and reported in published literature, e.g.,
reference 12.
2.4.12.2.2 Properties of the Water Table Aquifers Laboratory and field permeability testing was performed on the materials overlying the marl aquiclude at VEGP during early site investigations. The field tests indicated permeability values of 200 to 250 ft/ year and labora-tory tests indicated values of 10 to 20,000 ft/ year. These were the only quantitative tests performed in the water table aquifer. More comprehensive testing of hydrogeologic properties was considered unnecessary because (1) the VEGP does not use water from this aquifer and (2) the plant is situated on an interfluvial high which is hydraulically isolated from other similar aquifers.
- rN 2.4.12.2.3 Properties of the Cretaceous and Tertiary Aouifers As stated in paragraph 2.4.12.1.2, the Cretaceous and Tertiary aquifers are in hydraulic connection at the site (Figure 2.4-4).
The hydrolo-geologic properties of the combined Cretaceous / Tertiary aquifer were determined at the plant site by pumping tests on test well TW-1 during early site investigations and by pumping tests on makeup wells MU-1 and MU-2 during plant construction.
Table 2.4-3 summarizes aquifer characteristics as determined during both the test well program conducted in 1972 and the makeup water we'll installa-tion program completed in 1977. The moderately wide range of transmissivi-ties and storage coefficients shown on the table suggests that the aquifer is not uniform in character and that permeability varies from place to pl a.ce. No carticular significance is attached to this condition because (1) the range of differences is not especially large and (2) the lowest of the values (110,400 gal /d/ft) is still indicative of a highly productive
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TABLE 2.4-3
SUMMARY
OF AQUIFER CHARACTERISTICS CALCULATIONS
(..y Y'
Calculated Observation Transmissivity Storage Method of Analysis Point (s)
(gal /d/ft)
Coefficient Test Well Data (TW-1)
. Straight-line, Pumping well 158,000 (a) distance drawdown observation points Type-curve, time-1 196,000 6.6 x 10-4 drawdown Type-curve, time-2 160,000 3.3 x 10-*
drawdown
'r'S.
Type-curve, time-3 163,700 3.5 x 10-9 drawdown Type-cu rve, time-4 153,000 2.1 x 10-5 drawdown Type-curve, time-5 229,200
'3.9 x 10-4 drawdown Makeup Well Data
(
MU-1 and MU-2) l Type-curve, time-None 110,400 (a) j drawdown, MU-1 t.
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time None 116,600 (a)
E.1 Type-curve, recovery, MU-1 r-Type-curve, time MU-1 130,900 1.07 x 10-*
l drawdown, MU-2 l
L.-
Type-curve, time MU-2 128,700 (a)
M.
recovery, MU-2 l
l l
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a.
Storage coefficient calculated only from observation well data.
f
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. aquifer.
It is noteworthy that the 158,000 gal /d/ft value, determined from a distance-drawdown analysis and considered more indicative of the average, falls very close to the median value between the highest and lowest trans-missivities obtained.
This implies that the value of 150,000 gal /d/ft is a realistic and conservative value to be used in evaluating the capability of the area to yield water to wells.
The values of storage coefficient determined from the pumping tests indicate the aquifer is effectively confined.
2.4.12.3 Monitoring of Safeguard Requirements A comprehensive groundwater monitoring program has been implemented at the VEGP.
This program was designed (1) to monitor groundwater levels and movement in both the confined and unconfined aquifers for life of the plant and (2) to monitor levels of groundwater accumulating in the compacted backfill inside the power block excavation throughout construction.
The original program consisted of 9 observation wells set in the confined aquifer, 16 observation wells set in the unconfined aquifer, and 11 observa-tion wells set in the backfill.
Some of the backfill wells were located at sites of structures and were later abandoned.
Those not abandoned will be maintained for the permanent monitoring program.
Table 2.4-4, sheet 1, summarizes water levels measured during site exploration.
Table.2.4-4, sheets 2 and 3, summarizes piezametric levels that have been recorded since the monitoring program was reinitiated.
Contamination of usable groundwater by normal operation of VEGP, or by accidental spills, is unlikely.
The potential for such an ocurrence is very low.
The marl underlying the site is an effective barrier to migration of fluids.
Construction of the makeup water wells and the standby test well includes a cement grout seal to prevent movement of fluids into the well bore.
The pumping wells and observation wells placed beneath the marl aqui-
-clude provide a direct and available means of monitoring the confined ground-water aquifer, if it is considered desirable or should a question arise.
Samples may be taken immediately and analyses performed for prompt determination of any change in water cuality.
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8 TABLE 2.4-4 (SIIEET 1 OF 3)
WBTER LEVEL MEASUREMENTS AT OBSERVATION WELLS (PRIOR TO CONSTRUCTION POSTPONEMENT OF 1974)
Hi9 hest / Lowest Elevation or Ground Water for Year Shown (rt above msl)
Woll Surface 1971 1972 1973 1974 Notes flgm
{,,J gtys t ion High Low High Low High Low.
High Low observation Wells in,1 dater Table Aauirer 8s?ls 209.7 160 1 584 159 156 161 160 158 157 124 260.3 162 161 163 162 170 167 169 163 IP9 215.3 155 153 151 154 163 157 160 18 4 4
18 0 222.4 161 159 161 160 168 165 165 162 6
lis t 230.4 155 1 584 156 154 18s2 224.5 153 152 153 152 160 136 158 144 18s3 224.5 155 153 155 143 163 161 160 150 18s5 218.7 161 18 7 155 151 4
I/6 196.4 160 159 161 160 167 165 1 68:
162 171 213.0 161 161 163 160 170 167 165 162 Ito 240.4 159 157 16u 157 163 160 159 157 119 215.9 166 154 1/1 166 174 170 169 165 Pis 3 213.0 151 1846 148 147 147 18s6 Completed in 1972 P8 sis 212.6 165 161.
160 130 158 156 Completed in 1972 P4's 207.6 156 155 163 162 161 159 Completed in 1972 Pts /
211.3 162 159 Completed in 1972 P8su 166.8 162 161 Completed in 1972
?49 192.8 160 159 164 162 162 157 Completed in 1972 -
Obsqrvation Wells in Artesian Auulrer P4 216.0 122 116 120 116 123 116 122 117 P6 203.8 135 100 107 103 107 102 106 1084 2/
210.0 9 14 79 90 81 98 82 88 79 29 193.4 107 89 102 97 102 96 99 93 31 211.0 110 101 112 107 121 107 111 105 32 214.0 107 102 109 105 111 102 106 100 38:
86.0 102 101 Artesian flow except in 1972 4?A 210.5 204 82 102 99 111 107 110 105 19/1 high/ low not considered valid lutA 210.8 119 117 120 117 121 116 118 113 121 88.0 Artesian flow 13's 200.5 118 104 109 106 110 104 Artesian flow 18 sis 103.2 103 86 90 83 1971 and 1972 data not available lis t 226.2 118 115 118 116 185 117 119 116 High reading in 1973 not considered valid 2816 210.4 118 116 116 114 113 111 Completed in 1972 Ob se rva t ion We l l s i nJa rl Aoulclude 4 21s 210.4 187 118 126 118 139 139 42C 210.0 152 150 156 152 150 150 w"".
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TABLE 2.4-4 (SilEET 2 OF 3)
.o Ground Water Levois af ter Resumption of' Monitoring Program - 1979 Quarterly Ground Water t.evels f f't asil 19J9 1980 Wall Surface total Sc reened litterva l rio, _
ELovation Di!RLI) from_
10 6ctive"3 2nd 3 rd 4th
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2nd 3 rd 4th pbservation Wells in the Water Table Aquifer l.I-1A 200.7 77.3 62.3 72.3 Yes (e)
(e) 137.6 136.3 137.1 136.3 135.8 Il-1 200.4 13.2 58.2 68.?
Yes (c)
(e) 141.9 142.6 140.4 139.4 140.0 I?9(4 215.3 91.0 92.0 97.0 Yes 211.7 169.6 20f4.9 176.0 156.0 147.7 189.9 4
136 225.1 82.0 0
82.0 Noth)
!40 223.5 96.0 81.0 96.0 No th) 18a 1 223.6 100.0 90.0 100.0 No(h) 186.0 145.9 11 5.8 I t 2(M 224.5 95.0 85.0 95.0 Yes 217.6 222.0 (c)
(c) 4 t//
213.0 80.0 60.0 80.0 Nold) 168.1 158.5 158.6 158.2 159.7 159.3 (d)
I/9 275.9 131.0-111.0 131.0 Yes 160.2 161.8 161.1 157.9 162.0 161.7 161.1
/t 1 225.2 80.0 60.0 80.0 Noth) 6 600 215.7 9fs.0 69.0 89.0 Yes 158.3 159.1 159.0 158.7 160.0 158.5 159.3 158.8 155.8 154.7 155.8 155.3 1 584. 5 col 214.8 8 T.5 62.5 82.5 Yes 154.3 4
asoJ 217.8 94.0 69.0 79.0 Yes 150.5 132.1 150.8 150.7 1846. 1 151.2 150.6 tlO 3 A 220.3 87.0 57.0 77.0 Yes 156.0 155.1 155.1 1 581. 7 134.9 154.7 15f4.4 804 226.1 90.0 60.0 80.0 Yes 161.2 141s. 4 161.2 161.0 161.84 161.1 160.9 238.7 125.0 95.0 115.0 Yes 152.4 153.0 152.9 121.1 137.5 153.3 118.7 tiOSA 4
no611 217.5 70.0
$5.0 65.0 Yes (e)
(e)
Dry Dry Dry Dry Dry tsu/A 216.8 80.0 65.0 75.0 Yes (e)
(e) 156.1 158.1 158.9 158.7 158.1 9
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' Observation wells are'also placed in the water table aquifer and provide a means to monitor and sample the groundwater in the materials overlying the earl aquiclude. The monitoring program will continue for the life of the plant. Monitoring program observation wells are listed on Table 2.4-4.
-Their locations are shown on Figure 2.4-5.
2.4.12.4 Plant Operating Requirements Groundwater is the primary source of supply for reactor cooling water
- makeup, normal makeup to the nuclear service cooling towers, and fire protection. Two makeup wells (designated iiu-1 and MU-2 on figure
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2.4-5) producing from the combined Cretaceous / Tertiary aquifers supply water to storage tanks from which plant water is withdrawn as needed. Each well is capable of supplying the expected total quantity of makeup water for the two units (2000 gal / min) during normal operation. The two wells pumping (D
simultaneously have sufficient capacity to supply expected process makeup requirements and completely fill the major plant tanks in one day. The plant well system is not required for safe shutdown of the plant but is the normal source of water supplied as makeup to the ultimate heat sink.
The Savannah River is an independent alternate source also available for cooling water makeup.
(Seesection'2.4.11.)
2.4.12.5 Design Basis for Subsurface Hydrostatic Loading The applicant's design basis for Subsurface Hydrostatic Loading is elevation 165 ft ms1. The applicant has not provided sufficient data and bases for the staff to concur in the selected design basis level. Moreover, based on information available, it is the staff's judgement that the level is too low to be used as the probable maximum level for hydrostatic loading evaluations.
However, it may be acceptable as the approximate 25 year groundwater level that would be used for. dynamic load (combined SSE seismic event) evaluations.
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. The applicant value (165 ft ms1) is based on observation well readings during the site exploration program of 1971-1974. The applicant has only provided the annual high and low values for this period. The applicant needs to provide the monthly well readings and well locations. The staff will also require the monthly prec~ipitation values for the same period as the 71-74 well readings.
Quarterly well readings presented in the FSAR are not regarded by the staff as of sufficient quality for use in establishing a design basis groundwater level in this type of aquifer.
It is our opinion that during a 3 month period, it is possible to miss peak values that result from local intense rainfall.
A continuous record (well recorder) for at least one well in the plant backfill and one well in the undisturbed water table aquifer close to the power block area and at least weekly readings on all other wells would j.' " '
provide the type of data necessary to determine the design basis ground-water levels. Until this additional information is provided by the appilcant, the staff cannot conclude that the design basis groundwater level meets the requirements of GDC 2 and 10 CFR 100 with respect to groundwater. This remains an unresolved issue.
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. 2.4.13 ACCIDENTAL RELEASES OF LIQUID EFFLUENTS IN G3,00ND AND SURFACE WATER j
2.4.13.1 Consideration of Accidental Spill of Radioactive Material ih Groundwater Any radioactive fluid infiltrating the ground at the plant site would first move downward through the unsaturated zone to the water table. After reach-ing the water table, it would move laterally and discharge to the springs or seeps on the banks of the adjacent streams and eventually reach the Savannah River.
Thbmarlaquicludewillpreventfurtherdownwardmovementtoward^the confined aquifer.
The VEGP is situated on the northwest side of a relatively flat groundwater plateau.
Radionuclides released in the vicinity of the plant would probably migrate in a northwesterly direction to a spring about 3200 feet from the Unit 2 Containment Building (see Figure 2.4-6).
- However, there is another spring located about 2800 feet southeast of the Unit 1 g,g Containment Building that would be somewhat closer and would have a steeper average gradient.
Thus, although it is likely that the containment pathway would be in a, southeasterly direction, the staff conservatively assumed the groundwater pathway for a postulated tank spill would be to the spring 2800 feet southeast of the plant.
The time required for groundwater to migrate Or<1 this flow path is determined by the hydraulic conductivitp 4
t2ctive porosity of the materials and the gradient of the 'c:,'er table.- Both laboratory and field c
f tests were performed by the applicant to determine the hydraulic conductivity of the materials (see Section 2.4.12.5).
The field tests indicated permeabil-ity values of 200 to 350 ft/ year and the laboratory tests indicated values of 10 to 20,000 ft/ year. The staff considers field measurements to be much more reliable and representative of aquifer characteristics than laboratory values which represent only a small disturbed sample of the aquifer.
A value of 350 ft/ year is a very reasonable estimate of permeability for the water table aciuifer.
However, in light of the wide range of laboratory values quoted, the
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Hydraulic conductivity and permeability are used interchangeably in Section 2.4.
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.h staff selected an ultra conservative value of 8000 ft/ year for usa in determin-ing groundwater velocities.
The hydraulic gradient may be determined from the groundwater' contours shown on Figure 2.4-6.
The staff analysis of groundwater velocity used a gradient of 7.1 feet per 1000 feet. The applicant estimated the total. porosity of the sand to be 45 percent.
The staff used a conservative estimate of 30% for the effective porosity.
Seepage velocity, then, may be determined by the following relationship:
v=S "e
~
where:
v = seepage velocity (ft/ year).
k = coefficient of permeability or hydraulic conductivity (ft/ year).
~
i = hydraulic gradient (dimension 1ess).
j n, = effective porosity (dimensionless).
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Based on the above values and relationship the staff conservatively estimated the seepage velocity to be 189.3 ft/ year.
The travel time to the nearest spring (2800 feet) is then 14.8 years.
Using a more realistic value for hydraulic conductivity of 350 ft/ year, the groundwater velocity would be 8.3 ft/ year and the travel time to the spring (2800 feet) would be 338 years.
The staff evaluation of possible failure of tanks containing radioactive liquid determined that the Waste Evaporation Concentrate Holdup Tank (WECHT) is the critical tank with respect to radionuclide concentrations at the nearest potable water user in an unrestricted area.
This tank has a nominal volume of 2,500 gallons and is located inside the auxillary building at elevation 196 ft ms1 (plant grade at el 220 ft ms1).
This is a different tank than the one (Re-cycle Holdup Tank) evaluated by the applicant.
The radio-nuclide concentrations for the WECHT are provided in an internal NRC memo, C.~ A. Willis to R. Jachowski, Subject, " Liquid Radwaste Tank Failure Evaluation for VEGP, Unit Nos. 1 and 2," dated October 11, 1984.
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All of the radionuclides for the WECHT would be less than the 10 CFR Part 20 requirements at the spring 2800 feet southeast of the plant using the more realistic estimate of groundwater travel time of 338 years.
However, with the conservative groundwater. travel time of 14.8 years, several radionuclides with long half lives and/or high initial concentrations (Co 60, Sr 90, Cs 134 and Cs 137) exceed the 10 CFR Part 20 requirements at the spring and it is necessary to consider the effects of sorption.
These chemically active nuclides would travel through the groundwater pathway at a much slower rate because of the process of sorption onto the soil and rock media.
The degree of retardation is governed by the various physical properties such as bulk density, aquifer porosity and species equilibrium distribution coefficient.
The radionuclide concentration at the spring can be derived by the following expression:
-Aat C=Ce
,e,.
- r.
where:
C = final concentration C, = initial concentration A = in 2/t t = radionuclide half life (years) j a = 1 + g Kd n
L i
p = bulk density of aquifer media (gm/cm3) l l
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{,.
.q
. n = total porosity of aquifer Kd = distribution coefficient which is defined as the mass of radionuclide absorbed per gram of soil divided by the mass of radionuclide dissolved per milliliter of groundwater (cm3/gm) t = groundwater transport time (years)
A typical value of the ratio p/n is 5, however, the staff used a conservative value of 4.1.
The staff has made an extensive literature search of equi-librium distribution coefficients and selected a value of 100 for Co 60, Cs 134, and Cs 137 and a value of 10 for Sr 90.
Based on the above expression and conservative parameters, the staff calculated concentrations for the four critical radionuclides at the spring and they were all small fractions of the 10 CFR Part 20 requirements.
The spring and its drainage f
course to the river is all within the property boundary.
The nearest down-stream user in an unrestricted area is Beaufort / Jasper County 112 river miles downstream.
Thus, any acci. dental release of radionuclides would also be fully I ~)1 diluted in the Savannah River before reaching a potable water intake.
The c
combined ground and river water dilution factor is about 140,000 which is sufficient to reduce all radionuclides to small fractions of the 10 CFR Part 20 requirements.
Based upon our review using procedures described in SRP 2.4.13, we conclude that the plant meets the requirements of 10 CFR Part 100 with' respect to
. potential accidental release of radioactive effluents.
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2.4.14 Technical Specification and Emergency Operating Requirements i
At this time the staff has found no reason to require any Technical Specifications or Emergency Operating Requirements as provided in SRP 2.4.14.
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References 1.
Schreiner, Louis C., and Riedel, John T., " Probable Maximum Precipitation Estimates, United States East of the 105th Meridian,"
Hydrometeorological Report No. 51, National Weather Service, NOAA, U.S. Department of Commerce, Washington, D.C., 1978.
2.
Hansen, E. M., and Schreiner, L. C., " Application of Probable Maximum
-Precipitation Estimates, United States East of the 105th Meridian,"
Hydrometeorological Report No. 52 (preliminary), National Weather Service, Silver _ Springs, Maryland, 1979'.
3.
U.S. Army Corps of Engineers, South Atlantic Division, Water Resources Development in South Carolina, Atlanta, Georgia, March 1975.
4.
NRC memorandum, H. R. Denton to V. Stello, Jr., Subject, " Generic Requirements Regarding Design for Probable Maximum Precipitation", dated October 10, 1984.
5.
U.S. Army Corps of Engineers, HEC-1 Computer Program User's Manual, 1975.
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6.
U.S. Army Corps of Engineers, HEC-2 Water Surface Profiles, February 1972.
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Duke Power Company, Oconee Nuclear Plant Preliminary Safety Analysis 7.
Report, subsections 2.4.2 and 2.4.3.
8.
Tennessee Valley Authority, Computer Code Simulated Open Channel Hydraulics (SOCH), Transient Flow Mathematical Model, January 1972.
9.
Corps of Engineering Flood Emergency Plan.
10.
Department of the Interior, U.S. Geological Survey, Atlanta, statistical data on river flow, temperature, and chemical analyses for the Savannah
. River (data retrieved from USGS computer on July 8, 1981, for the Hydro Projects Department, Southern Company Services).
11.
Bechtel Power Corporation, " Studies of Postulated Millett Fault,"
October 1982.
, ~
Cedergren, H. R., Seepage, Drainage and Flow Nets, John Wiley, New 12.
York, p 489, 1967.
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