ML20209H069
| ML20209H069 | |
| Person / Time | |
|---|---|
| Site: | Satsop |
| Issue date: | 09/19/1985 |
| From: | Ballard R Office of Nuclear Reactor Regulation |
| To: | Johnson W Office of Nuclear Reactor Regulation |
| References | |
| CON-WNP-1381 NUDOCS 8509240304 | |
| Download: ML20209H069 (22) | |
Text
. _
n
)
i SEP 191985 Docket No. 50-508 MEMORANDUM FOR: William V. Johnston, Assistant Director Materials, Chemical & Environmental Technology, DE FROM:
Ronald L. Ballard, Chief Environmental & Hydrologic Engineering Branch, DE
SUBJECT:
REVIEW 0F THE WNP-3 DRAFT SER In an undated memo from Thomas Novak, you were asked to comment and concur with the WNP-3 draft SER. The attached is provided for your use in responding to Mr. Novak's memo.
We have reviewed Section 2.4 of the draft SER which is the only section provided by EHEB to Division of Licensing. We note that Figures 2.4.1 and 2.4.2, which were provided with our input, are missing from this draft SER.
Other comments are shown on the attached pages. This review was performed by R. Gonzales.
/Jf iN Ok/
Ronald L. Ballard, Chief F
Enviromental & Hydrologic j
Engineering Branch Division of Engineering
Attachment:
As stated cc:
B. K. Singh D. Chery R. Gonzales DISTRIBUTION:
LMcEets EHEB Rdg RLBallard/ file Yh w
0FC : DE:EH g DE:EHEB Q& DE:EHEB p ':
_____:______L.__
NAME:RGonzGfs,:'ws::_DLCheryn'RLBallard :
_____:-___________:___________P,____________:____________:____________:____________:__________
lDATE: 9/l9/85
- 9/M/35 I: 9/l4/ V :
.x 0FFICIAL RECORD COPY 8509240304 e50919 p
ADOCK 05000508 f
$l.Lpp.
L.
3 2.4 Hydrologic Engineering The staff has reviewed the hydrologic engineering aspects of the applicant's design, design criteria, and design bases for safety-related facilities at the Washington Public Power Supply System Nuclear Project No. 3 (WNP-3).
The acceptance criteria used as a basis for staff evaluations are set forth in SRP2.gthrough2.p4(NUREG-0800).
These acceptance criteria include the applicable GDC reaMor site criteria (10 CFR 100), and standards for protection against radiation (10 CFR 20, Appendix B, Table II).
Guidelines for implemen-tation of the requirements of the acceptance criteria are provided in RGs, ANSI standards,andBranchTechnicalPositions(BTPs)identifiedinSRP2g.4 through V^
2].44.
Conformance to the acceptance criterie provides the bases forconcluding /
tTrat the site and facilities meet the requirements cf 10 CFR 20, 50, and 100 with respect to hydrologic engineering.
2.4.1 Hydrologic Description WNP-3 is located in Satsop, Washington, approximately 1.4 miles south of the Chehalis River near the confluence of the Satsop River.
The site is about 26 miles west of Olympia and about 16 miles east of Aberdeen, Washington.
As g,t}.
shownonhure2.$CWNP-3issituatedonaridgebetweenWorkmanCreekand the Chehalis River.
The Chehalis River which heads in the Willapa hills in southwest Washington, flows generally eastward to the city of Chehalis where it. changes its course abruptly to the north.
About 10 miles north of Chehalis, near Grand Mound, the rive.- flows northwesterly to Elma, then west to Grays Harbor at Aberdeen.
The river and its tributaries have a drainage area of about 2,115 mi2 The drainage area at the site, including the Satsop River, is about 1,765 mi2, The average annual flow at this ation is about 6,820 cfs.
The Chehalis River basin is shown on Figur 2.4.
gy
[
The major tributaries of the Chehalis River in the vicinity of the site are the Satsop and Wynoochee Rivers.
The Satsop River has a drainage area of about 300 mi2 and an average annual flow of about 2030 cfs.
The Wynoochee River has a drainage area of about 100 mi2 and an average annual flow of about 1200 cfs.
03/25/85 2-17 WNP-3 DSER SEC 2
~~
~
Both of these tributaries rise on the south side of the Olympic Mountains and flow southward to their confluences with the Chehalis River.
A number of small tributaries to the south of the Chehalis River head in the hills sur-rounding the site.
These include:
Elizabeth Creek, Hyatt Creek, Fuller Creek, Purgatory Creek and Workman Creek.
All of these streams are relatively short, intermittant streams, originating at elevations between 300 to 400 feet above mean sea level (MSL).
As shown on Figur re are two dams and associated reservoirs on the tributaries of the Chehalis River.
The Wynoochee dam and lake, which is a Corps of Engineers project, provides water supply for industry and agriculture and storage for flood control.
The lake also offers recreation opportunities for the public.
The Skookumchuck dam and reservoir project is operated by the Pacific Power and Light Company (PP&Ls).
The reservoir provides makeup water for PP&L's Centralia Steam Electric Station.
The water resources of the Chehalis River valley include both surface and ground supplies.
Within 5 miles of the plant, surface water permits have been granted by the Washington State Department of Ecology to about 78 users.
Most surface water is used for irrigation, witn the remainder for domestic use, livestock watering, fish propagation, fire protection and industrial use.
Except for a single domestic water user located within a mile downstream of the plant, there are no knowng%stsers of Chehalis River water for domestic purposes between o
t-i the plant and Grays Harbor.
l Groundwater in the Chehalis River valley is obtained'from shallow wells which tap the alluvial aquifer and is used mostly for drinking and irrigation.
I There are 45 known wells within 2 miles of the plant.
Five major municipal water systems within 20 miles of the site are served partially or totally by groundwater.
The applicant has provided hydrologic descriptions of the plant site and vicinity.
The staff has reviewed the applicant's information in accordance with l
procedures in SRP 2.4.1.
The staff concludes that the requirements of GDC 2 and 10 CFR Part 100, with respect to general hydrologic descriptions, have been met.
03/25/85 2-18 WNP-3 DSER SEC 2
]
h pet The applicant does not state whether the surrounding walls are equipped with scuppers or other means of limiting water depths.
Therefore, it is possible that water could pond to a much greater depth than 32.06 inches because the walls are at least 26 feet high (443.5 feet 417.5 feet).
The applicant should 4
thus consider rainfall for durations greater than 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />.
The effect of a 26 foot depth of water should be addressed unless it can be demonstrated that water cannot physically pond to this depth.
Alternately, the applicant should consider putting scuppers (or other devices) in walls to limit water depths to those that can be supported safely by the roof section adjacent to the steam tunnel.
The staff has reviewed the material presented by the applicant in the FSAR, using the procedures described in SRP Section 2.4.2.
Based on this review, the staff concludes that the applicant has not provided sufficient information to support its conclusions that ponded water will not enter safety-related buildings or that the roof section adjacent to the steam tunnel is capable of supporting potential rainfall loads.
Thus the staff cannot conclude at this time, that the plant meets the requirements of GDC 2 with respect to flooding by intense local precipitation.
The staff, however, does conclude that during a PMP event, water levels on roofs of safety-related structures will remain at or below the levels determined by the applicant except for the roof adjacent to the steam tunnel.
2.4.3 Probable Maximum Flood on Streams and Rivers The Probable Maximum Flood (PMF) is defined as the hypothetical precipitation-i induced flood that is considered to be the most severe reasonably possible.
I Severe rainfall storms in western Washington occur mostly in the winter months when there is snow on the ground.
Consequently, the applicant estimated the PMF for the Chehalis River based on PMP and snowmelt over the drainage basin.
As a first step in estimating the PMF, the applicant subdivided the Chehalis River drainage basia into three subbasins and developed individual unit 03/25/85 2-22 WNP-3 DSER SEC 2
rged #
hydrographs for each subbasin using Corps of Engineers procedures.
A flood hydrograph was then developed for each subbasin using the Corps of Engineers floodhydrographcomputerprogram, HEC).
To determine a PMF for each subbasin, each hydrograph was then increased by the average annual river flow to account for base flow conditions.
The three individual PMF's were then routed, where appropriate, and combined at the site to form a single PMF.
To account for potential antecedent flood conditions as recommended in RG 1.59, the applicant assumed that a storm equal to 50 percent of the PMP would occur three days prior to the PMP storm.
The antecedent flood resulting from these conditions was combined with the PMF at the site.
The resultant hydrograph had a peak g
dischargeof353,]00cfs.
g PMF water levels in the Chehalis River adjacent to the site were determined by means of the Corps of Engineers HEC 2, " Water Surface Profiles" computer program.
The PMF discharge (353,000 cfs) stillwater level was estimated to be 53.1 feet MSL.
The applicant determined that coincident windwave activity would result in a maximum wave runup, including wind setup, of 23.1 feet.
Adding this to the PMF stillwater level resulted in a maximum flood level of 76.2 feet MSL.
Since the plant is at elevation 390 feet MSL, the applicant concluded that no safety-related structures would be affected by a PMF on the Chehalis River.
l The applicant did not address the potential for flooding from the small creeks near the site; however, based upon the following observations, the staff con-cluded that floods on these small creeks will not affect the safety of the plant.
l Workman Creek which runs south of the plant has a stream bed elevation which is more than 200 feet lower than the plant grade elevation.
Because the drainage area of this creek is small, less than 10 mil?s, the staff concludes that a PMF 2
would not rise 200 feet in the creek.
In addition to Workman Creek, there are two other creeks in the vicinity, Fuller Creek and Purgatory Creek.
Both of these have drainage areas of less than one mile 2 and each creek flows away from i
the plant.
The staff thus concludes that floods on these creeks will not I.
affect the safe operation of WNP-3.
l 03/25/85 2-23 WNP-3 OSER SEC 2
m
~
=.
~'
At the CP stage, the staff reviewed the applicant's analyses and the effects of coincident windwave activities.
The staff concurred then with the applicant's analysesandconcludedthatthereisnopotentialdangertosafetgelated structures due to the PMF with coincident waves.
The staff has reviewed the FSAR material presented by the applicant in accordance with procedures described in SRP 2.4.2 and 2.4.3.
Based on this review, the stoff concludes that the plant meets the guidelines of RG 1.59, " Design Basis Floods for Nuclear Power Plants", and the requirements of GDC 2 with respect to flooding from the Chehalis River and the small creeks adjacent to the site.
2.4.4 Potential Dam Failures gM As shown i ure 2.4.2 the only dam located upstream of the plant is Skookumchuck Dam.
The applicant estimated the effect of a failure of this dam coincident with a Standard Project Flood (SPF) equal to one half of the PMF.
It was assumed that the reservoir would be full at the time the dam failed.
Using Corps of Engineers procedures, the applicant estimated a dam failure hydro-graph with a peak discharge of 260,000 cfs.
This hydrograph was routed down-stream and combined with SPF's from the Chehalis River subbasins.
The resultant peak flow at the site was determined to be 182,000 cfs.
Using the same proce-dures as were used to determine PMF levels, the applicant determined the flood level at the site due to failure of Skookumchuck dam would be 39.6 feet MSL.
Since this elevation is less than the PMF level, the applicant concluded that failure of Skookumchuck Dam will not affect the safety of the plant.
l The staff reviewed the applicant's dam failure analysis at the CP stage and l
concluded that there would be no flooding of the plant due to dam failures.
j The staff has reviewed Section 2.4.4 of the FSAR, using the procedures l
described in SRP 2.4.4.
The staff concurs that conservative procedures have been used and that potential dam failures pose no threat to the plant.
Thus the staff concludes that the plant meets the requirements of GDC 2 and 10 CFR 100, Appendix A, with respect to flooding by dam failures.
l l
i l
03/25/85 2-24 WNP-3 DSER SEC 2
,]
]
~
2.4.7 Ice Effects The Pacific ocean, which is about 30 miles west of the si.te, greatly influences the climate in the WNP-3 area.
The ocean acts to moderate the seasonal" and daily variability in climate throughout the year such that winters are warmer than at other locations at similar latitudes.
Because of this, there are no conditions which might produce a permanent ice cover or ice jam on the Chehalis River.
In addition, because of the large difference in elevation between the Chehalis River and the plant (Sect'on 2.4.3), even if ice jams did form, floods resulting from these jams would not affect the safe operation of Q a space uk [ L )AS$ h-) Y Water required for normal operation of WNP-3 will be supplied from groundwater infiltration, type structures (Ranney Wells).
Therefore, potential icing will not affect the normal plant water supply.
Emergency safe shutdown and cool down of WNP-3 can be accomplished using the ultimate heat sink which consists of dry cooling towers located adjacent to the reactor auxiliary building.
Make-up water is not required for the dry cooling towers and during periods of low temperature the design of the towers prevents freezing of the tower or pipelines.
The staff has reviewed the information provided by the applicant concerning ice effects, in accordance with procedures in SRP 2.4.7.
The staff concludes that icing will not affect the safe operation of the plant.
2.4.8 Cooling Water Canals and Reservoirs There are no safety-related or other cooling water canals or reservoirs associated with WNP-3.
2.4.9 Channel Diversions The Chehalis is a meandering river that shows a number of former channel locations, oxbows and sloughs in the vicinity of the plant g Figure 2.4.1).
As described in Section 2.4.11.1, the source of makeup water for the WNP-3 cooling tower is the alluvial aquifer that underlies the Chehalis River flood-plain.
Recharge to the aquifer occurs all across the river valley as well as 03/25/85 2-26 WNP-3 OSER SEC 2
t m
.m 9
in the river channel and from the 70 to 80 inches of annual rainfall in the The aquifer reacts much like a reservoir by accepting and storing sur-area.
face inflow during periods of high river flows and high rainfall and releasing the stored water when rainfall and river flows aren't as plentiful.
Since the aquifer is recharged by both rainfall and the river across the entire valley it is possible for the river channel to meander considerably before the makeup water capability would be affected.
f Water for plant use is withdrawn from the aquifer by means of two Ranney wells located as shown o re 2.4.1 As part of the design to place Ranney col'-
lectors in the floodplain, the adjacent river banks are being stabilized to minimize erosion.
However, because the Chehalis is a meandering river, display-ing oxbows and sloughs, diversion affecting the Ranney wells is still considered possible.
Regardless of the availability of the Ranney wells, the safety of the plant will not be jeopardized because, as described in Section 2.4.11.2, emergency cooling of the plant can be accomplished using the ultimate heat sink, which consists of a dry cooling tower.
The staff thus concludes that potential channel diversions, although remote, present no safety-related hazard to the plant and that the requirements of 10 CFR Part 100, relative to channel diversions, have been met.
2.4.10 Flood Frotection Requirements As described in Section 2.4.3, the staff concluded that the plant is located considerably higher than any credible flood in the Chehalis River.
- However, in Section 2.4.2, the staff concluded that the applicant had not provided sufficient information to support its conclusion that local intense precipita-tion will not enter safety-related buildings.
Additionally, it is not evident that a roof section adjacent to the steam tunnel has been designed to support potential ponded rainfall.
The applicant will be required to provide additional information in support of its conclusions.
Resolution of these issues will be addressed in a supplement to this SER.
I l
03/25/85 2-27 4 P-1 DSER SEC 2
m m
i
~
I l
2.4.11 Cooling Water Supply 2.4.11.1 Normal Water Supply W,
Under normal operating conditions, waste heat will be dissipated to the atmosp-here by a natural draft cooling tower.
Makeup water to replace the water lost by evaporation, blowdown and drift, will be supplied to the cooling tower by two Ranney wells located in the alluvial aquifer whicn underlies the Chehalis River valley Figure 2.4.
To prevent excessive buildup of dissolved solids in the cooling system, a certain amount of cooling water inust be contin-uously discharged to the Chehalis River after first being cooled dcwn by a supplemental cooling facility.
The blowdown discharge will be diluted in tne river through the use of a submerged multiport diffuser.
The maximum makeup water requirement for WNP-3 is approximately 18,000 gpm (40.0 cfs), and a single Ranney well is capable of supplying this amount on a continuous basis.
The capability of the Ranney wells to supply this quantity of watei is independent of low flows in the Chehalis River.
The State Energy Facility Site Evaluation Council (EFSEC), however, has administratively est&b-lished that plant makeup withdrawal (except for a hot standby maintenance flow of 2 cfs) must cease when the daily river flow goes below 550 cfs. Additionally, plant withdrawal may not exceed the difference between the river flow and 550 cfs.
The long-term annual average flow of the Chehalis River at the site is estimated to be about 6820 cfs.
The estimated average montnly ficws vary from 730 cfs in August to 14,900 cfs in January.
The minimum and maximum historical flows at the site are estimated to be about 400 and 97,100 cfs, respectively.
Because of the water withdrawal limitation established by the EFSEC, the plant will have to be shut down whenever the daily river flow goes below 550 cfs.
The applicant estimates that, on the average, this will occur about four days a year, The applicant has completed a contract with the city of Aberdeen to purchase releases of 62 cfs of flow from the Wynoochee Reservoir to supplement the l
03/25/85 2-28 WNP-3 DSER SEC 2
.t
m, m
N Groundwater also occurs in a discontinuous manner in the pleistocene terrace deposits.
Recharge is derived from infiltration of rainfall on the areas above the terrace levels and infiltration from the Chehalis River.
There arq no known major aquifers within these deposits and only three domestic wells tap the terrace groundwater in small perched aquifers.
The only satisfactory source of groundwater in the site vicinity occurs in the alluvial aquifer that underlies the Chehalis River valley.
This aquifer extends downward from about 10 feet telow the ground surface to about 165 feet.
The high permeability and transmissivity coefficients of this unconfined aquifer indicate that the aquifer reacts much like a reservoir and a hydraulic conduit.
Racharge to the aquifer oc:urs all across the river valley as well as in the river channels from the 70 to 80 inches of annual precipitation in the area and from the high surface inflow from the widespread Chehalis River basin.
The aquifer accepts surface water for storage during these periods until the under-ground storage is full.
The permeable aquifer discharges readily into streams and rivers during periods of low flow.
The alluvial aquifer is limited hori-zontally by tertiary sandstone sediments on the south side of the river and by by the scuthern edge of the Olympic Mountains on the north side of the valley.
The aquifer extends two miles across the Chehalis River valley, about 14 miles downstream to Grays Harbor ar.d about 15 miles upstream to the eastern limit of Grays Harbor County. As described in Section 2.4.11.1, this aquifer will be used to supply makeup water to the plant.
2.4.12.2 Dewatering System A permanent groundwater drainage systein (GWDS) that operates solely by gravity has been installed around the WNP-3 reactor auxiliary building (RAB).
The GWDS consists of vertical 6 inch diameter half-round drain pipes spaced at 8.5 feet intervals around the RAS at the interface between the rock and exterior concrete Theverticalpipes,whichdranthesboundin rock, M from phmt.
walls.
To e evakcri
& M5L g d... the base of t.he foundation mat except at the west side of the RAB where 3
the vertical drain pipes extend into the turbine building, four feet above the flocr e'levation of 390 feet MSL.
This elevation is above the highest level (3 feet) that the applicant has estimated circulating water could rise, in the event of a Circulating Water System break inside the building.
08/02/85 2-31 WNP-3 DSER SEC 2
q a
Thus any water released into the Turbine Building would be prevented from directly entering the GWDS.
Groundwater that seeps into the vertical drain pipes is conveyed to a 5 inch diameter horizontal drain pipe located along the periphery of the mat.
Collec-ted groundwater is then routed to a 6 foot diameter drainage tunnel that drains into a small tributary of Workman Creek south of the plant.
In addition, 8 inch diameter perforated undermat drains have been placed diagonally beneath the foundation mat.
These undermat drains are also connected to the drainage tun-nels. Manholes are provided at each corner of the RAB to allow for periodic inspection and cleaning of the GWDS.
The GWDS is not classified as a seismic Category I system except for the man-holes at the corners of the RAB and trie upper 5 feet of the extended vertical drain pipes at the west side wall of the RAB.
The manholes are seismic Cate-gory I to provide access to the horizontal drain pipe and to the drainage tun-nel in the event of an earthquake.
The upper portions of the vertical drain pipes are seismically qualified to resist the passive pressure of the sandstone on the embedded portion of the pipes and to resist the peak seismic accelera-tion of the RAB at grade elevation.
The applicant has stated that in the unlikely event of a complete blockage of the GWDS, the walls and foundation mat of the RAB are designed to withstand the resulting hydrostatic load of a grcundwater level at elevation 365 feet MSL.
This elevation is 39 feet abbve the bottom of the mat, elevation 326 feet MSL, g
and eet below the plant grade elevation of t MSL. The applicant states that in the event of a complete blockage of the GWDS, there would be sufficient time to repair the system before the surrounding groundwater would rise to an elevation of 365 feet MSL.
This time was estimated to be a minimum of 115 days.
weel a.(-) kfAf.
(UsingtheproceduresinGP2.4.12includingBranchTechnicalPosition(BTB)
HGEB1, the staff has reviewed the information provided by the applicant ir, the FSAR.
The staff concludes that there is inadequate information with which to assess the applicant's conclusion that in the event of a complete failure of the dewatering system there will be sufficient time to repair the system before the surrounding groundwater would rise to an unacceptable level.
The staff 08/02/85 2-32 WNP-3 DSER SEC 2
r, 8
UNITED STATES 8"
NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. :;0555 t%,,,,
SEP 191955 Docket No. 50-508 MEMORANDUM FOR: William V. Johnston, Assista'it Director Materials, Chemical & Environmental Technology, DE FROM:
Ronald L. Ballard, Chief Environmental & Hydrologic Engineering Branch, DE l
SUBJECT:
REVIEW 0F THE WEP-3 DRAFT SER /
In an andated memo from Themas Novak, you were asked to comment and cortcur_.
wich the WNP-3 draft SER. The attached is provided for your use in responding to Mr. Novak's memo.
I We have reviewed Section 2.4 of the draft SER which is the only section provided by EHEB to Division of Licensing. We note that Figures 2.4.1 and 2.4.2, which were provided with our input, are missing from this draft SER.
Other comments sre shown on the attached es. This review was performed by R. Gonzales.
\\
' ' ")
t
)
i n
O onald L. Ballard, Chief T
Environmental & Hydrologic i
Engineering Branch Division of Engineering
Attachment:
As stated cc:
B. K. Singh D. Chery p
R. Gonzales
~%
4 H,q.
~
q t
W r
I y
._q n
2.4 Hydrologic Engineering The staff has reviewed the hydrologic engineering aspects of the applicant's design, design criteria, and design bases for safety-related facilities at the Washington Public Pcwer Supply System Nuclear Project No. 3 (WNP-3).
The i
acceptance criteria used as a basis for staff evaluations are set forth in SRP2.gthrough2.
4 (NUREG-0800).
These acceptance criteria include the applicaole GGC reaLor site criteria (10 CFR 100), and standards for protection against radiation (10 CFR 20, Appendix 8, Table II). Guidelines for implemen-tr. tion of the requirements of the acceptance criteria are provided in RGs, ANSI standards, and Branch Technical Positions (BTPs) identified in SRP 2.4 through /
2,414.
Conformance to the acceptance criteria provides the bases fo concluding #
t.,at the site and facilities meet the requirements of 10 CFR 20, 50, and 100 with respect to hydrolcgic engineering.
2.4.1 Hydrologic Description WNP-3 is located in Satsop, Washington, approximately 1.4 miles south of the Chehalis ?.iver near the confluence of the Satsop River.
The site is about 251;iles gst of Olympia and about 16 miles east of Aberdeen, Washington.
As Ugt}
shownonligure2.gQWNP-3issituatedonaricgebetweenWorkmanCreekand
/
the Chehalis River.
+
@ *%r W Q The Chehalis River which heads in the Willapa hills in southwest Washington, flows generally eastward to the city of Chehalis where it changes its course
.sbruptly to the north. About 10 miles norta of Chehalis, near Grand Mound, the river flows northwesterly to Elma, then west tc Grays Harbsr at Aberdeen.
The river and its tributaries have a drainage area of abodt 2,U S ni2 The drainage arca at the site, including the Satsop River, is about 1,765 mi2 The average annual flow at this.12 Cation is about 6,G20 cfs.
The Chehalis River basin is shown on Figur gy I
The major tributaries of the Chenalis River in the vicinity of the site are the Satsop and Wyr.oocnee Rive 7s.
The Satscp ?.n er has a drainage area of abo 9t 300 m12 and an average annual flow cf atout 2050 cfs.
The Wynoocnee River has a drafnage area of about 100 mi2 ar.d an aw rage annual ficw of acout 1200 cfs.
03/25/85 2-17 KNP-3 OSER SEC 2
Both of these tributaries rise on the south side of the Olympic Mountains and flow southward to their confluences with the Chehalis River.
A number of small tributaries to the south of the Chehalis River head in the hills sur-
~
rounding the site.
These include:
Elizabeth Creek, Hyatt Creek, Fuller Creek, j
Purgatory Creek and Workman Creek.
All of these streams are relatively short, intermittant streams, originating at elevations between 300 to 400 feet above mean sea level (MSL).
As shown on Figur re are two dams and associated reservoirs on the tributaries of the Chehalis River.
The Wynoochee dam and. lake, which is a Corps of Engineers project, provides water supply for industry and agriculture and storage for flood control.
The lake also offers recreation opportunities for the public. The Skookumchuck dam and reservoir project is operated by the Pacific Power and Light Company (PP&Ls).
The reservoir provides makeup water for PP&L's Centralia Steam Electric Station.
The water resources of the Chehalis River valley include both surface and ground supplies. Within 5 miles of the plant, surface water permits have been granted by the Washington State Department of Ecology to about 78 users.
Most surface water is used for irrigation, with the remainder for domestic use, livestock' watering, fish propagation, fire protection and industrial use.
Except for a single domestic wat r user located within a mile downstream of the plant, o er there are no knowng sers of Chehalis River water for domestic purposes between the plant and Grays Harbor.
. Groundwater in the Chehalis River valley is obtained from shallow wells which tap the alluvial aquifer and is used mostly for drinking and irrigation.
There are 45 known wells within 2 miles of the plant.
Five major municipal water systems within 20 miles of the site are served partially or totally by groundwater.
The applicant has provided hydrologic descriptions of the plant site and vicinity.
The staff has reviewed the applicant's information in accordance with procedures in SRP 2.4.1.
The staff concludes that the requirements of GDC 2 and 10 CFR Part 100, with respect to general hydrologic descriptions, have been met.
03/25/85 2-18 WNP-3 DSER SEC 2
}
0 The applicant does not state whether the surrounding walls are equipped'with scuppers or other means of limiting water depths.
Therefore, it is possible l
that water could pond to a much greater depth than 32.06 inches because the walls are at least 26 feet high (443.5 feet'417.5 feet).
The applicant should A
thus consider rainfall for durations greater than 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />.
The effect of a 26 foot depth of water should be addressed unless it can be demonstrated that water cannot physically pond to this depth.
Alternately, the applicant should consider putting scuppers (or other devices) in walls to limit water depths to those that can be supported safely by the roof section adjacent to the steam
- tunnel, i
The staff has reviewed the material presented by the applicant in the FSAR, using the procedures describ'ed in SRP Section 2.4.2.
Based on this review, the staff concludes that the applicant has not provided sufficient information to support its conclusions that ponded water will not enter safety-related buildings or that the roof section adjacent to the steam tunnel is capable of supporting potential rainfall loads.
Thus the staff cannot conclude at this time, that the plant meets the requirements of GDC 2 with respect to flooding by intense lo, cal precipitation.
The staff, however, does conclude that during a PMP event, water levels on roofs of safety-related structures will remain at or below the levels determined by the applicant except for the roof adjacent to the steam tunnel.
2.4.3 Probable Maximum Flood on Streams and Rivers The Probable Maximum Flood (PMF) is defined as the hypothetical precipitation-induced flood that is considered to be the most severe reasonably possible.
Severe rainfall storms in western Washington occur mostly in the winter months when there is snow on the ground.
Consequently, the applicant estimated the PMF for the Chehalis River based on PMP and snowmelt over the drainage basin.
As a first step in estimating the PMF, the applicant subdivided the Chehalis River drainage basin into three subbasins and developed individual unit 03/25/85 2-22 WNP-3 DSER SEC 2
3 m
If hydrographs for each subbasin using Corps of Engineers procedures.
A flood hydrograph was then developed for each subbasin using the Corps of Engineers floodhydrographcomputerprogram, HEC).
To determine a PMF for each subbasin, each hydrograph was then increased by the average annual river flow to account for base flow conditions.
The three individual PMF's were then routed, where appropriate, and combined at the site to form a single PMF.
To account for potential antecedent flood conditions as recommended in RG 1.59, the applicant assumed that a storm equal to 50 percent of the PMP would occur three days prior to the PMP storm.
The antecedent flood resulting from these conditions was combined with the PMF at the site.
The resultant hydrograph had a peak g
dischargeof353,J00cfs.
g PMF water levels in the Chehalis River adjacent to the site were determined by means of the Corps of Engineers HEC 2, " Water Surface Profiles" computer program.
The PMF discharge (353,000 cfs) stillwater level was estimated to be 53.1 feet MSL.
The applicant determined that coincident windwave activity would result in a maximum wave runup, including wind setup, of 23.1 feet.
Adding this to the PMF stillwater level resulted in a maximum flood level of 76.2 feet MSL.
Since the plant is at elevation 390 feet MSL, the applicant concluded that no safety-related structures would be affected by a PMF on the Chehalis River.
The applicant did not address the potential for flooding from the small creeks near the site; however, based upon the following observations, the staff con-cluded that floods on these small creeks will not affect the safety of the plant.
Workman Creek which runs south of the plant has a stream bed elevation which is more than 200 feet lower than the plant grade elevation.
Because the drain:ge area of this creek is small, less than 10 miles, the staff concludes that a PMF 2
would not rise 200 feet in the creek.
In addition to Workman Creek, there are two other creeks in the vicinity, Fuller Creek and Purgatory Creek.
Both of these have drainage areas of less than one mile 2 and each creek flows away from the plant.
The staff thus concludes that floods on these creeks will not affect the safe operation of WNP-3.
i 03/25/85 2-23 WNP-3 DSER SEC 2
3 0
,j g h At the CP stage, the staff reviewed the applicant's analyses and the effects of coincident windwave activities.
The staff concurred then with the applicant's analysesandconcludedthatthereisnopotentialdangertosafetgelated
[
structures due to the PMF with coincident waves.
The staff has reviewed the FSAR material presented by the applicant in accordance with procedures described in SRP 2.4.2 and 2.4.3.
Based on this review, the staff concludes that the plant meets the guidelines of RG 1.59, " Design Basis Floods for Nuclear Power Plants", and the requirements of GDC 2 with respect to flooding from the Chehalis River and the small creeks adjacent to the site.
O 2.4.4 Potential Dam Failures y
As shown i ure 2.4.2 the only dam located upstream of the tant is Skookumchuck Dam.
The applicant estimated the effect cf a failure of this dam coincident with a Standard Project Flood (SPF) equal to one half of the PMF.
It was assumed that the reservoir would be full at the time the dam failed.
Using Corps of Engineers procedures, the applicant estimated a dam failure hydro-graph with a peak discharge of 260,000 cfs.
This hydrograph was routed down-stream and combined with SPF's from the Chehalis River subbasins.
The resultant peak flow at the site was determined to be 182,000 cfs.
Using the same proce-dures as were used to determine PMF levels, the applicant determined the flood level at the site due to failure of Skookumchuck dam would be 39.6 feet MSL.
Since this elevation is less than the PMF level, the applicant conc.luded that failure of Skookumchuck Dam will not affect the safety of the plant.
The staff' reviewed the applicant's dam failure analysis at the CP stage and l
concluded that there would be no flooding of the plant due to dam failures.
The staff has reviewed Section 2.4.4 of the FSAR, using the procedures described in SRP 2.4.4.
The staff concurs that conservative procedures have been used and that potential dam failures pose no threat to the plant.
Thus the staff concludes that the plant meets the requirements of GDC 2 and 10 CFR 100, Appendix A, with respect to flooding by dam failures.
03/25/85 2-24 WNP-3 DSER SEC 2
3, 3
2.4.7 Ice Effects The Pacific ocean, which is about 30 miles west of the site, greatly influences the climate in the WNP-3 area.
The ocean acts to moderate the seasonal and daily variability in climate throughout the year such that winters are warmer i
than at other locations at similar latitudes.
Because of this, there are no conditions which might produce a permanent ice cover or ice jam on the Chehalis River.
In addition, because of the large difference in elevation between the Chehalis River and the plant (Section 2.4.3), even if ice jams did form, floods resulting from these jams would not affect the safe operation of the plant.
['")
geelc Space u5d A A
Water required for normal operation of WNP-3 will be supplied from groundwater infiltration, type structures (Ranney Wells).
Therefore, potential icing will not affect the normal plant water supply.
Emergency safe shutdown and cool down of WNP-3 can be accomplished using the ultimate heat sink which consists of dry cooling towers located adjacent to the reactor auxiliary building. Make-up water is not required for the dry cooling towers and during periods of low temperature the design of the towers prevents freezing of the tower or pipelines.
The staff has reviewed the information provided by the applicant concerning ice effects, in accordance with procedures in SRP 2.4.7.
The staff concludes that icing will not affect the safe operation of the plant.
2.4.8 Cooling Water Canals and Reservoirs There are no safety-related or other cooling water canals or reservoirs associated with WNP-3.
2.4.9 Channel Diversions
~
The Chehalis is a meandering river that shows a number of formepchannel r
locations, oxbows and sloughs in the vicinity of the plant g Figure 2.4.
As described in Section 2.4.11.1, the source of makeup water for the WNP-3 cooling tower is the alluvial aquifer that underlies the Chehalis River flood-plain.
Recharge to the aquifer occurs all across the river valley as well as d3/25/85 2-26 WNP-5 PSER SEC 2
?
m 9
in the river channel and from the 70 to 80 inches of annual rainfall in the The aquifer reacts much like a reservoir by accepting and storing sur-area.
face inflow during periods of high river flows and high rainfall and releasing the stored water when rainfall and river flows aren't as plentiful.
Since the aquifer is recharged by both rainfall and the river across the entire valley I
it is possible for the river channel to meander considerably before the makeup water capabfifty would be affected.
?
(A Water for plant use is withdrawn from the aquifer by means of two Ranney wells located as shown o Figure 2.4.1 As part of the design to place Ranney col-lectors in the floodplain, the adjacent river banks are being stabilized to minimize erosion.
However, because the Chehalis is a meandering river, display-ing oxbows and sloughs, diversion affecting the Ranney wells is still considered possible.
Regardless of the availability of the Ranney wells, the safety of the plant will not be jeopardized because, as described in Section 2.4.11.2, emergency cooling of the plant can be accomplished using the ultimate heat sink, which consists of a dry cooling tower.
The staff thus concludes that potential channel diversions, although remote, O
present no safety-related hazard to the plant and that the requirements of 10 CFR Part 100, relative to char.nel diversions, have been met.
2.4.10 Flood Protection Requirements As described in Section 2.4.3, the staff concluded that the plant is located considerably higher than any credible flood in the Chehalis River.
- However, l
in Section 2.4.2, the staff concluded that the applicant had not provided l
l sufficient information to support its conclusion that local intense prec1 pita-tion will not enter safety-related buildings.
Additionally, it is not evident that a roof section adjacent to the steam tunnel has been designed to support potential ponded rainfall.
The applicant will be required to provide additional information in support of its conclusions.
Resolution of these issues will be l
addressed in a supplement to this SER.
03/25/85 2-27 WNP-3 OSER SEC 2 L
,i i
i 2.4.11 Cooling Water Supply 1
2.4.11.1 Normal Water Supply i
,yI4WJ Under normal operating conditions, waste heat will be dissipated to the atmosp-t here by a natural draft cooling tower.
Makeup water.to replace the water lost by evaporation, blowdown and drift, will be supplied to the cooling tower by two Ranney wells located in the alluvial aquifer which underlies the Chehalis N
1 River valley see Figure 2.4.
To pre. vent excessive buildup of dissolved solids in the cooling system, a certain amount of cooling water must be contin-uously discharged to the Chehalis River after first being cooled down by a supplemental cooling facility.
The blowdown discharge wil! be diluted in the river through the use of a submerged multiport diffuser.
The maximum makeup water requirement for WNP-3 is approximately 18,000 gpm (40.0 cfs), and a single Ranney well is capable of supplying this amount on a continuous basis.
The capability of the Ranney wells to supply this quantity of water is independent of low flows in the Chehalis River.
The State Energy Facility Site Evaluation Council (EFSEC), however, has administrative,1y estab-lished that plant makeup withdrawal (except for a hot-standby maintenance flow of 2 cfs) must cease when the daily river flow goes below 550 cfs.
Additionally, plant withdrawal may not exceed the difference between the river flow and 550 cfs.
The long-term annual average flow of the Chehalis River at the site is estimated to be about 6820 cfs.
The estimated average monthly flows vary from 730 cfs in August to 14,900 cfs in January.
The minimum and maximum historical flows at the site are estimated to be about 400 and 97,100 cfs, respectively.
Because of the water withdrawal limitation established by the EFSEC, the plant will have to be shut down whenever the daily river flow goes below 550 cfs.
The applicant estimates that, on the average, this will occur about four days a year.
The applicant has completed a contract with the city of Aberdeen to purchase releases of 62 cfs of flow from the Wynocchee Reservoir to supplement the 03/25/85 2-28 WNP-3 DSER SEC 2
3 Groundwater also occurs in a discontinuous manner in the pleistocene terrace deposits.
Recharge is derived from infiltration of rainfall on the areas above the terrace levels and infiltration from the Chehalis River.
There arq no known major aquifers within these deposits and only three domestic wells tap i
the terrace groundwater in small perchod aquifers.
The only satisfactory source of groundwater in the site vicinity occurs in the 1
1 alluvial aquifer that underlies the Chehalis River valley.
This aquifer extends
)
downward from about 10 feet below the ground surface to about 165 feet.
The high permeability and transmissivity coefficients of this unconfined aquifer l
indicate that the aquifer reacts much like a reservoir and a hydraulic conduit.
Recharge to the aquifer occurs all across the river valley as well as in the river channels from the 70 to 80 inches of annual precipitation in the area and from the high' surface inflow from the widespread Chehalis River basin.
The aquifer accepts surface water for storage during these periods until the under-ground storage is full.
The permeable aquifer discharges readily into streams and rivers during periods of low flow.
The alluvial aquifer is limited hori-zontally by tertiary sandstone sediments on the south side of the river and by by the southern edge of the Olympic Mountains on the north side of the valley.
The aquifer extends two miles across the Chehalis River valley, about 14 miles downstream to Grays Harbor and about 15 miles upstream to the eastern limit of Grays Harbor County.
As described in Section 2.4.11.1, this aquifer will be used to supply makeup water to the plant.
2.4.12.2 Dewatering S'ystem I
l A permanent groundwater drainage system (GWDS) that operates solely by gravity j
has been installed around the WNP-3 reactor auxiliary building (RAB).
The GWDS consists of vertical 6 inch diameter half-round drain pipes spaced at 8.5 feet intervals around the RAB at the interface between the rock and exterior concrete The vertical pipes, which fr g e surg undi ggock, b from pte t.
walls.
goede=4ethebaseofthefoundationmatexceptatbewestsideoftheRA8where 3
l the vertical drain pipes extend into the turbine building, four feet above the floor elevation of 390 feet MSL.
This elevation is above the highest level (3 feet) that the applicant has estimated circulating water could rise, in the event of a Circulating Water System break inside the building.
f 08/02/85 2-31 WNP-3 DSER SEC 2
Thus any water released into the Turbine Building would be prevented from directly entering the GWDS.
2 Groundwaterthatseepsintotheverticaldrainpipesisconveyedtoa5 inch j
diameter horizontal drain pipe located along the periphery of the mat.
Collec-i ted groundwater is then routed to a 6 foot diameter drainage tunnel that drains j
into a small tributary of Workman Creek south of the plant.
In addition, 8 inch diameter perforated undermat drains have been placed diagonally beneath the foundation mat. These undermat drains are also connected to the drainage tun-nels.
Manholes are provided at each corner of the RAB to allow for periodic inspection and cleaning of the GWDS.
The GWDS is not classified as a seismic Category I system except for the man-holes at the corners of the RAB and the upper 5 feet of the extended vertical drain pipes at the west side wall of the RAB.
The manholes are seismic Cate-gory I to provide access to the horizontal drain pipe and to the drainage tun-nel in the event of an earthquake.
The upper portions of the vertical drain pipes are seismically qualified to resist the passive pressure of the sandstone on the embedded portion of the pipes and to resist the peak seismic accelera-tion of the RAB at grade elevation.
The applicant has stated that in the unlikely event of a complete blockage of the GWDS, the walls and foundation mat of the RA8 are designed to withstand the resulting hydrostatic load of a groundwater level at elevation 365 feet MSL.
This elevation is 39 feet above the bottom of the at elevation 326 feet MSL, v'
14.5
. 5,-
/ '
and 95 feet below the plant grade elevation of ft MSL.
The applicant states that in the event of a complete blockage of the GWDS, there would be sufficient time to repair the system before the surrounding groundwater would rise to an elevation of 365 feet MSL.
This time was estimated to be a minimum of 115 days.
weedo.(-)hhtt Using the procedures in SRP 2.4.12 including Branch Technical Position (BTB)
HGEB, the staff has reviewed the information provided by the applicant in the FSAR.
The staff concludes that there is inadequate information with which to assess the applicant's conclusion that in the event of a c'omplete failure of
~
the dewatering system there will be sufficient time to repair the system before the surrounding groundwater would rise to an unacceptable level.
The staff 08/02/85 2-32 WNP-3 DSER SEC 2
+
.-e
--