ML20198G292
| ML20198G292 | |
| Person / Time | |
|---|---|
| Site: | Washington Public Power Supply System |
| Issue date: | 02/12/1975 |
| From: | Harold Denton Office of Nuclear Reactor Regulation |
| To: | Moore V Office of Nuclear Reactor Regulation |
| References | |
| CON-WNP-1039 NUDOCS 8605290429 | |
| Download: ML20198G292 (20) | |
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i TR: DOCKET FILE FEB 121975 TR: Rdg TRISAB V. A. Moore, Assistant Director for LWR, Group 2, RL HYDROLOGIC ENGINmTNG SU!OfARY (SER) i PLANT Nt.ME: WPPSS Nuclear Projects 1 & 4 LICENSING STAGE: CP i
DOCKET 13JH3EitS 50-460/513 i
RESPONSIBLE BRANCH LWR 2-3 REQUESTED COMPLETION DATE: J:anuary 23, 1975
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REVIEW STATUS: Hydrologic Engineering Section, SAB - Complete, Except for Open Items Listed Below Enclosed is the hydrologic engineering summary (SER) on the subject plant, prepared by G. B. Staley and E. Hawkins, for your use in preparing the Safety Evaluation Report. The summary indicates the following two
. :n items:
1.
Flooding of safety related structures due to runoff fro:a a local intense storm.
2.
The Ultimate Heat Sink spray pond water volume is not adequate for the 30 day period and the spray efficiency of 40% that was assumed for the spray nozzles is considered by the staff to be too high.
A conservative value would be between 20 and 25 parcent.
We would have no objections to deferring both of these items to the j
FSAR, if the applicant can provide assurances that any associated changes I
would have no affect on construction.
l OrigkalSigned by it. R. Denton Harold R. Denton, Assistant Director l
r for Site Safety Division of Technical Review Office of Nuclear Reactor Regulation Enclosures As Stated l
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ISTRIBUTION:
T ' Docket File TR: g TR:S l
V. A..
- e. Assistant Director for LWR, Group 2, Pl.
HTDROLOGI ENGINEERING SUMMART (SER)
PLANT NAME:
PSS Nuclear Projects 1 & 4 LICENSING ST t CP DOCKET NUMBERS: 50-460/513 RESPONSIBLE BRAN : LWR 2-3 REQUESTED COMPLETI DATE: January. 23, 1975 REVIEW STATUS: Hyd ogic Engineering Section. SAB - Complete.
Except for Open It Listed Below Enclosed is the hydrolog engineering summary (SER) on the subject plant, prepared by B. Staley and E. Hawkins, for your use in preparing the Safety aluation Report. The summary indicates i
the following two open items:
- 1. Flooding of safety related at tures (including roof penetrations) due to runoff from a local inten atorm.
- 2. The tiltimate Heat Sink spray pond w er volume is not adequate for the 30 day period and the spray e iciency of 40% that was assumed for the spray r.ozzles is consi ed by the staff to be too high. A ccuservative value would be tween 20 and 25 percent.
We would have no objections to deferring both o these itets to the FSAR, if the applicant can provide assurances hat any associated changes would have no affect on constrtetion.
Harold R. Denton, Assis t Director
. j for Site Safety i
Division of Technical Ravi Office of Nuclear Reactor Reg ation
Enclosure:
As stated t
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4 HYDROLOGIC ENGINEERING SU E\\RY WASHINGTON PUBLIC POWER SUPPLY SYSTEM NUCLEAR PROJECTS 1 & 4 DOCKET NO. 50-460/513
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2.4. HYDROLOGIC ENGINEERING 2.4.1.
HYDROLOGIC DESCRIPTION ' The site for Washington Public Power Supply System (WPPSS) Nuclear ' Projects one and four (the plant) is located in the southeast area of the Hanford Reservation in Benton County, Washington, 8 miles north of the city limits of Richland, about 2.5 miles west of the Columbia river at river mile 352 and 45 miles downstream from the Grant County Public Utilities District Priest Rapids Dam. The Columbia River is the predominant hydrologic feature of the area and provides the principle drainage for the site and surrounding area. The Columbia River, upstream of the plant site, has a drainage area of about 97,000 square miles. The major tributary upstream of the site is the Wenatchee River. The Snake and Yakima River enter the Columbia River'just downstream of the site. Regulation of the Columbia River by dams and reservoirs ha's been extensive over the past 35 years.
A large portion of the main stream and major tributaries is developed to meet various functional requirements such as flood control, navigation, hydroelectric power, irrigation, and municipal and industrial water supply. The following Table 2.4.1 lists the dams on the Columbia River upstream of the site and dams on the tributaries above Grand Coulee Dam.
Table 2.4.2. lists tributary dams between Grand Coulee Dam and the plant.
site. The regulated average annual Columbia River flow at the site is 115,000 cfs. During the year the flow may vary upward from a regulated
TABLE 2.4.1 UPSTREAM COLUMBIA RIVER DAMS
( AND ITS TRIBUTARIES ABOVE GRAND COULEE )
CREST GROSS USABLE NAME OF DAM RIVER MILE TYPE HEIGHT LENGTH STORAGE STORAGE (ft)
(ft)
(1000 Acre-ft) (1000 Acre-ft)
Priest Rapids 397 Concrete Gravity 100 10,137 200 170 5/
and earth fill Wanupum 416 Concrete Gravity 133 8,707 796 389 5/
and earth fill Rock Island 453 Concrete Gravity 73 3,800 5
Rocky Reach 474 Concrete Gravity 140 2,900 390 120
& earth fill Wells 516 Concrete Gravity 160 4,460 300 117
& carth fill Chief Joseph 545 Concrete Gravity 205 4,383 518 Grand Coulee 598 Concrete Gravity 355 4,173 9,402 5200 Albeni Falls 90 2/
Concrete Gravity 66 1,055 1,560 1.153 Hungry Horse 5 6/
Concrete Arch 520 2,115 3,468 3,160 Kerr Dam 77]/
Concrete Arch 186 800 1,22D 1,219 Arrow 1/
781 Concrete Gravity 170 7,090
& earth fill Mica 1/
1018 Rockfill 640 12,000
TABLE 2.4.1 (CONTINUED)
UPSTREAM COLUMBIA RIVER DAMS
.( AIO ITS TRIBUTARIES ABOVE GRAND COULEE )
CREST GROSS USABLE NAME OF DAM RIVER MILE TYPE HEIGHT LENGTH STORAGE STORAGE (f.t)
(ft)
(1000 Acre-ft)
(1000 Acre-f t)
Duncan 1/
8.3 3/
Earthfill 130 1,400 Libby 220 4/
Concrete Gravity 370 5,000 1/
These projects located in Canada are part of the Columbia River Treaty Storage as is Libby on the United States side.
2/
The river mile shown is on the Pend Oreille River, which joins the Columbia River at Columbia R. M. 745.5 3/
Duncan River Miles, Duncan River flows into Kootenai Lake in Canada.
4/
Kootenai River Miles, the Kootenai River joins the Columbia River at Columbia R. M. 774.1 5/
Not presently usable for flood regulation.
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South Fork Flathead River Miles.
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Clark Fork River Miles.
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TABLE 2.4.2
. TRIBUTARY DAMS LOCATED BETWEEN GRAND COULEE DAM AND PLANT SITE CREST CROSS INAME OF DAM RIVER MILE TYPE llEIGHT I.ENGTil 3TORAGE (ft)
(ft)
(1000 A F)
Chelan 3 6/
Concrete 40 677 0 Sullivan 42 1,5/
Zoned earth fill 153 19,000 615.6 Billy Clapp 85 1,5/
Zoned earth fill 130 1
Banks 99 1,5/
Zoned earth fill 123 762 Snow Lakes 312/
Concrete Gravity 12 13 Conconully 48 3/
Ilydraulic Earth 70 1000 13 Salmon Lake 49 3/
Zoned earth fill 42 1260 11 Owhi 16 4/
Earth fill 14 5
.1/
The river mile shown is on Crab Creek. Crab Creek enters the Columbia River at River Mile 411.
2/
The river mile shown is upstream from the mouth of the Wenatchee River. The Wenatchee River enters the Columbia River at River Mile 468.
3/
The river mile shown is upstream from the mouth of the Okanogan River.
The Okanogan River enters the Columbia River at River Mile 533.
4/
The river mile shown is upstream from the mouth of the Nespelem River. The Nespelem River enters the Columbia River at River Mile 582.
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' TABLE 2.4.2 (CONTINUED) i 5/
Part of the Columbia Basin Project' and used solely for stroage of irrigation water.
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The river mile shown is on the Chelan River. The Chelan River joins the Columbia f
River at Columbia River Mile 503.3.
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F 1 low of 36,000 cfs.
The main river channel near the site varies from 400 to 600 yards in width and in depth from about 30 feet for normal high water to about 45 feet or more for flood high water.
The approximate river bottom elevation near the site is 328 feet above mean sea level datum (f t MSL). The,
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ground elevation at the site is about 445 ft MSL, and will.be raised to an approximate elevation of 451 f t MSL. The lowest seismic Category I
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structure will be at elevation 446 f t MSL.
At the present time there are no ground water users on either side of the river in the vicinity of the site. Ground water will be used during plant construction at rates of between 950,000 and 4,200,000 gallons per month. There are 32 surface water users with registered water rights in the 50 miles reach downstream of the site. Most of the users are withdrawing water for irrigation and industrial purposes. There are three users, the cities of Richland and Pasco and one private individual, that withdraw water for domestic or municipal uses.
In addition, the city of Kennewick obtains its water indirectly,from the river thru a system'of Ranney collectors that draw both ground and river water. With exception of the river' intake structure, all the structures are located about 2.5 miles west of the Columbia River. The river intake structure is to be on the west bank of the Columbia River and is capable of supplying river make-up water from river stages between elevations 342 and 373 ft MSL.
. 2.4.2 FLOODING The largest flood recorded on the Hanford reach of the Columbia River occurred in 1948 and had an observed peak discharge of 690,000 cfs. The largest known historical flood occurred on June 7, 1894, and had a peak discharge, estimated from high water marks, of 800,000 cfs.
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There is no record of major faulting in the site area due to ice jams.
Ice blockage is most likely to occur when water temperatures are aircady low, when flows are small, and when a significant cold spell occurs.
With the completion of Grand Coulee and other dams on the Columbia River main stem, the seasonal temperature and flow cycles have been drastically altered. These changes are coupled in such a way to reduce the intensity and timing of the conditions which rany contribute to a potential ice blockage and flooding situations. Average winter flow rates have increased, the low extreme temperatures have risen over the years, and water temperatures have shown a shif t in time so that peak temperatures now occur 30-45 days later than formerly. In the event that ice blockage should occur, the potential for flooding can be greatly reduced by controlled river release rates at the upstream dams. It can be concluded from these observations and studies, and the recorded observations of 25 years of operation of the llanford Production plants involving critical flows for nuclear safety, that the potential for ice blockage or the combination of blockage and flooding behind ice dams is so low as to be considered insignificant.
In any event, ice flooding will not be a major deterent to the make-up water pumphouse, and it would not effect the capability to shut down the reactor in a safe and orderly manner because of the availability of the ultimate heat sink spray ponds at the site.
The applicant used an unregulated and regulated PMF developed by the U.
S. Army Corps of Engineers (1) (2)as the design basis precipitation flood for the site. The peak discharge for the unregulated PMF is 1,600,000 cfs and 1,440,000 cfs. for the regulated PMF. The predicted river elevation (based upon Corps of Engineers profiles) for these flows is 392.0 and 389.0 ft MSL respectively.
Since all safety,related plant structures are at or above elevation 446.0 f t MSL, it is concluded that flooding due to a PMF has no significance to the safety of the plant.
The river intake structure is not a safety related structure.
The applicant has analyzed two types of storms to evaluate the effects of a local intense storm at the site. The analysis produced a calculated Probable Maximum Precipitation (PMP) of 10.1 inches over a 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> period for a general storm and 9.2 inches of precipitation in 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> for a thunderstorm. The applicant has analyzed the runoff from the PMP and has concluded that the channel west of the site will have sufficient slope and capacity to convey these flood waters away from the site and that the highway and railroad will not have an adverse affect on the flood stages. The applicant has also stated that flows will not buildup around safety related buildings due to the high permeability and percolation factors and the mild slopes used to take advantage of these rates.
We have concluded that the applicant's analyses of site precipitation and subsequent runoff hydrograph are acceptable. However, the applicant has not provided any analysis of roof drainage systems and their ability
. to convey runoff from heavy precipitatio,n floeds without flooding of roof penetrations. Nor has he provided an acceptable analysis of the site drainage, in that, no consideration was given to the condition of frozen ground at the beginning of the 6-hour thunderstorm, with subsequent ability of present grading and drainage systems to convey these flows to the main channel with no flooding of safety related buildings.
The applicant has used two studies by the Seattle District Corps of Engineers to define the potential river stage at the site due to a seismically induced dam failure of Grand Coulee Dam.
The results of these studies indicate that the flood would have a peak flow rate of 8,800,000 cfs at Grand Coulee Dam at the moment of breaking, and flow rate at the 'ite, (including 400,000 cfs base flow) of 4,800,000 cfs.
s This flow would produce a peak stage at the site estimated at 422.5 ft MSL. An additional foot was added to account for a higher postulated Regulated Standard Project Flood (RSPF) of 570,000 cfs. One foot of stage was also added to account for wind wave activity for a total stage at the site of 424.5 ft MSL. The analysis included the assumption that all reservoirs were full and that'a partial failure occurred at all downstream reservoirs, causing a release of their pools to the flood.
The staff has reviewed this subject extensively for other reactor sites along the Columbia River.
From this conservative analysis it can be concluded that safety related facilities are safe from floods of this nature.
. 2.4.3 Ultimate Heat' Sink The Ultimate Heat Sink (UHS) for the plant has two sources of water (1) the river intake structure, which is not a Seismic Category I structure;and (2) a 300 ft x 250 ft Seismic category I spray pond for each unit. The spray ponds are designed to provide a 30 day supply of water in the event of a loss of coolant accident (LOCA) and/or loss of offsite power (LOOP). They must also provide'this water at a temperature less than the maximum allowable for equipment operation.
The applicant used the following parameters or assumptions in his analyses of the UHS heat and water budgets.
1.
Percentage of heat rejected by spraying equals 80% (Ref.3). The range from Reference 3 was from 65% to 80%.
2.
Cooling efficiency of spray nozzles equals 40% (Ref.3.).
3.
Drift loss equals 0.8% (Ref.3).
4.
Wet bulb temperature equals 74*F for developing spray pond temperature response.
5.
The maximum evaporation rate was based on the maximum daily average dry bulb temperature of 91.8'F and the lowest monthly average rela-tive humidity of 21.9% (Wet bulb temperature of 65'F) for the 30 day period.
These values were assumed to occur simultaneously:. with the highest drift rate.
In addition there were some other conservatisms built into the analysis as follows:
1.
During actual operation, the sprays will be bypassed when the I
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temperature goes below 80*F and until it goes ba'ck up to 85'F.
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. This is expected to save a significant amount of drift.
2.
A constant flow rate was used in the analysis but in actual operation flow rates will be controlled by the heat load. This should reduce drift loss.
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The only time that it will be necessary to depend solely on the pond water supply is when the river intake capability is not available.
Loss of the river water supply could be due to a seismic event, flooding, or low water due to ice blockage or drought. Flooding and low water due to ice blockage are discussed above in section 2.4.2 and low water due to drought is discussed in the following section 2.4.4.
We have concluded that the applicant's analysis is not acceptable in regard to the 30 day water supply available and the assumed 40% nozzle spray efficiency. The 9 foot minimum pump submergence specified in Table 9.2-7 limits the minimum usable pond level to elevation 425.0. f t.
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MSL, which is 4 feet above the bottom of the pond. The assumed nozzle spray efficiencies of 40% have not been justified by field testing to conclude that it is a conservative value. Until further justification of higher nozzle spray efficiencies can be provided, it is our position that the value used to estimate pond performance be no greater than 20 to 25 percent.
2.4.4 LOW RIVER FLOW COMSIDERATIO,' S Reservoir projects in the Columbia d
River Basin upstream of the proposed site have a total usable storage in excess of 35 million acre-feet. This capacity alone is sufficient to maintain a flow in the Columbia River, at the proximity of the plant, of 36,000 cfs for over one year with no inflow from other sources. Because of this regulation, the anticipated minimum and maximum monthly mean~
flow rates will be 60,000 and 260,000 cfs in the vicinity of the proposed site.
In the 18 years, since closure of Priest Rapids Dam, the minimum flow rate has been 36,000 cfs.
It is concluded that it is improbable that the flows in the vicinity of the site will be less than the minimum regulated value of 36,000 cfs. However, in the unlikely event that lower flows should occur, on an infrequent basis, they would not affect the safety of the plant since it can be brought to a safe shutdown condition through use of the ultimate heat sink spray ponds.
2.4.5 CROUND WATER Three principal hydrologic zones underlie the Hanford Reservations as follows:
(1) Unconsolidated silts, sands, and gravels (glaciofluviatile sediments).
(2) Semiconsolidated lake and stream sediments (Ringold Formation)
(3) Dense, hard basalt which forms the bedrock beneath the area.
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. In general, ground water in the surficial sediments occurs under unconfined or water-table conditions. However, locally confined zones do exist in the area. Water in the basalt bedrock occurs mainly under confined conditions.
In some areas, the lower zone of the Ringold Formation is a confined aquifer, separated from the unconfined aquifer by thick clay.
beds and possessing a distinct hydraulic potential. The d'epth to the water table varies greatly from place to place depending chiefly on the local topography, ranging from less than 1 to more than 300 feet below the land surface. At the site the water table is from 72 to 85 feet below the land surface.
The current estimate of the maximum saturated thickness of the unconfined aquifer is approximately 230 feet. From the proposed site, the groundwater flow is toward the discharge boundary at the Columbia River to the east of the site. The hydraulic gradient in this area is about 10-13 feet / mile in the unconfined aquifer.
There are no groundwater users between the site and the river and reversal /(due to pumping) of the groundwater gradient is highly improbable because the sitd is located on Federally owned and controlled land. The applicant has estimated that it would take several hundred years for any postulated i
accidental spill of liquid radwaste at the plant site to travel vertically through the 70-85 foot depth to the ground water table.
It would take i
another 10 -35 years to travel thru the aquifer to the Columbia River.
The dilution by mixing with a Columbia River flow of 36,000 cfs has been estimated by the applicant to be about 770 at a point 3 miles downstream of the plant. The dilution was estimated to be about 3400 at a flow of I
120,000 cfs.
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9 The staff has independently estimated the ground water travel time to the Columbia River to be about 6.2 years. The dilution by mixing with ground water will be about 64 and by dispersion will be negligible.
Refer to section 15.2.4 for a discussion of radionuclide concentrations.
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4.6 CONCLUSION
S We have reviewed the applicant's flood analysis for the plant site, including determination of the maximum river stages on the Columbia River due to PMF, ice, and dam failures and flood conditions at the site and on roof tops due to local intense precipitation of up to PHP severity. We have concluded that the maximum predicted flood levels on the Columbia River are conservative and acceptahle. All safety related structures, except the river intake structure, will be above any reasonably possible Columbia River flood stage'.
The river intake structure will be designed for' river stages up to elevation 373.0 ft MSL, which
. corresponds to a Columbia River discharge of approximately 400,000 cfs (compared to the 1948 observed record peak discharge of 690,000 cfs at a stage of about 375.0 f t MSL). Although the river intake would be subject to. flooding by rare floods, and subsequent loss of pump function, the plant can still be brought to a safe shutdown condition and maintained for a pericd of 30 days through use of the two seismic category I spray ponds.
t However, we, find that the applicant has not fully considered flooding due to intense precipitation on roofs of safety related structures, and F
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that the analysis of local site drainage does not consider the effects of a 6 hour6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> thunderstorm occurring when the ground is frozen, which would negate the assumption of high infiltration rates adequate to prevent water buildup around safety related structures. The applicant will be required to furnish, in the FSAR, additional analysis of the ability to convey local flood flows away from safety related buildin~gs, analysis of roof drainage for the PMP and details of the floodway sections for the road and railroad.
We have found the applicant's analysis of low flows to be acceptable, and although there is a possibility of the occurrence of river flows less than 36,000 cfs, it is unlikely te happen during the life of the plant.
Even if these flows should occur, they would be for a short duration of time, and the plant can be brought to a safe shutdown condition through use of the UHS spray ponds, if necessary.
Since the ground water table has a significant gradient toward the river, is below foundation levels, and there are no groundwater withdrawal between the site and the river, it is concluded that in the event of a postulated accidental liquid radwaste spill, the groundwater will not Le a potential pathway to man.
We have reviewed the applicant's analysis of the UHS spray ponds with respect to pond temperatures and water loss over a 30 day period, and conclude that there maybe insufficient water in the pond to maintain the plant in a safe shutdown condition for 30 days. We have also concluded
. - that the analysis and subsequent predicted pond temperature of 93*F is not conservative. The nozzle efficiency of 40% has not been adequately substantiated, and the applicant should use a value of between 20 and 25 percent or provide adequate substantiation of the values used. We would have no cbjection to deferring these items on the URS to the FSAR if the applicant can provide assurances that any subsequent changes will have no affect on construction.
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REFERENCES (1) Artificial Flood Possibilities on the Columbia River, U.S. Army, Corps of Engineers, Seattle District, Seattle, Washington, Nov.
1951.
(2) Artificial Flood Considerations for Columbia River Dams, U.S. Army Engineer District, Seattle, Corps of Engineers, Seattle, Washingt'on,
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August 1963.
(3) Schrock, V.
E.,
and Trezek, G.
J., " Rancho Seco Nuclear Service Spray Ponds Performance Evaluation", University of California, Berkeley.
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