ML20039D289

to Environ Rept

ML20039D289
Person / Time
Site:	Limerick
Issue date:	12/31/1981
From:	PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
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ML20039D263	List: ML20039D262 ML20039D281 ML20039D289
References
ENVR-811231, NUDOCS 8112310496
Download: ML20039D289 (44)

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1 i

. LIMERICK GENERATING STATION UNITS 1-& 2 ZNVIRONMENTAL REPORT - OPERATING LICENSE STAGE REVISION 2 PAGE CHANGES The attached Revision 2 pages, tables, and figures are con-sidered part of a controlled copy of the Limerick Generating.

Station EROL. This material should be incorporated into the EBOL b/ following the collating instructions below:

Remove _ Insert Dated Volume 3 5.1-3 & 4 5.1-3 & 4 12/81 & 12/81' 5.1-5 & 6 5.1-5 & 6 12/81 & 12/81 5.1-7 & 8 5.1-7 & 8 12/81 &112/81 5.1-9 10 5.1-9 & 10 12/81 & 12/81 5.1-41 5.1-41 12/81 Table 5.1-1 Table 5.1-1(Pgs 1-3) 12/81 Figure 5.1-1 Figure 5.1-1 12/81 Volume 4

() E240.3-1 E240.ll-1 E240.12-1 E240.3-1 E240.ll-1 E240.12-1 12/81 12/81 12/81 E240.13-1 E240.13-1 12/81 E240.15-1 E240.15 12/81 E240.16-1 E240.16-1 12/81 E240.17-1 E240.17-1 12/81 E240.19-1 E240.19-1 12/81 E240.21-1 E240.21-1 thru 4 12/81 E240.22-1 E240.22-1 12/81 E240.23-1 E240.23-1 12/81 O

v 8112310496 811 70 15 2 PDR ADOCK 05 'WI K-

LGS EROL in t \

(,) of the total discharge. Therefore cooling tower blowdown is the only heat source considered in the following analysis of thermal effects.

Discharge through the diffuser will cause a rapid dilution of the effluent in the Schuylkill River. For typical river flows it is estimated that the effluent will become fully mixed in that portion of the Schuylkill River which passes over the diffuser.

This estimate is based on the results of MIT laboratory model studies on the performance of submerged diffusers in shallow water (Ref 5.1-2).

The initial mixing zone is the region in which nozzle velocities are dissipated and the effluent is fully mixed with the river flow passing over the diffuser. The estimates of downstream extent of the mixing zones given above are based on methods presented in Reference 5.1-75. For average conditions (river flow rate of 1910 cfs, diffuser flow rate of 26.8 cfs), the initial mixing zone will be about 150 feet wide and 30 feet long (Figure 5.1-1). For a high river flow rate of 9800 cfs (1%

exceedance value), the resulting dilution of the effluent woulC be much greater and the mixing zone would extend about 150 feet downstream. The areas of these initial mixing zones for average and high river flow conditions are approximately 0.1 and 0.5 acre, respectively. The mixing zone area for river flows lower l

[  ; than average will be less than 0.1 acre.  !

\_/

At river current velocity of 1 foot per second (which is less than the mean velocity for average flow), an organism would pass through the initial mixing zone in about 0.5 and 2.5 minutes for average and high river flow rate conditions, respectively.

Table 5.1-1 gives effluent flow rates, dilution factors, and temperature rises for the discharge plume for monthly' cooling tower blowdown temperatures with 50, 5 and 1% probabilities of exceedance. Under average stream flow conditions and all blowdown temperature conditions, even a sudden commencement or cessation of discharge flow would not cause the river temperature outside the small area of initial dilution to be changed by more than 2 F during any one-hour period. Under extreme low flow conditions, a 3-hour gradual commencement or cessation of discharge would not cause the river temperature to be changed by more than 2 F during any one-hour period. The only set of conditions for which the temperature rise limitation of 5 F is exceeded is for the 1% exceedance blowdown temperature for October and for the 7-day, 10-year low river flow. Even under this unlikely combination of extreme conditions, the computer temperature rise (5.3*F) is only slightly above the limit. It is apparent that the likelihood of effluent temperatures being a constraint on plant operation is very small. The dilution

() factors presented in Table 5.1-1 also apply to the dilution of

\_,' chemical constituents in the effluent (Section 5.3).

5.1-3 Rev. 2, 12/81

LGS EROL In the Environmental Report-Construction Permit Stage (Ref.

5.1-3) and the Final Environmental Impact Statement (Ref. 5.1-4),

a constant blowdown of 20 cfs was assumed to mix with one-half the river flow. Since that time, the system design has been finalized. Minor changes have been made to the nozzle design, system controls, and the diffuser location. The blowdown flow rate has been determined to vary between 30 and 32 cfs. One-half to one-third of the river flow will pass over the diffuser. It has been conservatively assumed that the effluent will have become diluted in one-third of the river flow.

5.1.3 BIOLOGICAL EFFECTS The following discussion of the biclogical effects of the heat dissipation system is based primarily on information gathered by the Applicant's ecological consultant in the Schuylkill River, Perkiomen Creek, and East Branch Perkiomen Creek (Sections 6.1 and 2.2), as well as design and operational parameters presented in tne ERCP (PECo, Ref 5.1-3) and FES (USAEC,'Ref 5.1-4), and simulated real time plant operating conditions. Chemical effects are discussed in Section 5.3.

General: No rare, threatened, or commercially valuable species were found in 9 years of collecting (1970-1978). Although all three potentially affected streams suffer from past or present anthropogenic activities (Section 2.2.2), all are biologically productive and diverse.

Schuylkill River: Only minor impact is expected on all biotic components (Section 2.2) as a result of intake operation and thermal discharge, due to the low proportion of total flow withdrawn and the small localized increase in temperature, respectively. At present the area near LGS is lightly utilized for sport fishing. However, the river was recently designated Pennsylvania's first scenic river, which probably increases its potential for recreational development. Water quality has been improving and is expected to continue to improve. An American shad restoration program has been initiated by the Pennsylvania Fish Commission. The river near LGS is not of unique importance for the life-sustaining activities of resident aquatic organisms, and the discharge will under no conditions block fish movement past LGS.

Perkiomen Creek: Diversion, by increasing flow and wetted area, should slightly benefit creek biota between the East Branch confluence and intake, especially in low flow years. A relatively large percentage of total flow will be withdrawn by the Graterford intake, but intake design (Wedge wire screen) is expected to minimize impingement, and entrainment is expected to have little or no impact on phytoplankton, zooplankton, or macrobenthos. Fish entrainment will be reduced by use and location of the wedge wire screens. The creen near Graterford is not of unique importance for the life-sustaining activities of Rev. 2, 12/81 5.1-4

LGS EROL lN_

(s) resident aquatic organisms. Water level fluctuations downstream of the intake will affect, through alternating inundation and exposure, a small area of stream bottom and associated resident biota. There is presently an active sport fishery on Perkiomen Creek.

' East Branch Perkiomen Creek: Changes in abundance and distribution are expected here for some biota in response to diversion. Changes related to flow augmentation (principally through elimination of intermittent flow in the headwaters and improved water quality in the middle and lower reaches) will generally be beneficial to the creek ecosystem through enhancement of community productivity and diversity. The recreational fishery is expected to improve. Diversion may

< introduce species here and on Perkiomen Creek that have not yet been recorded from these creeks.

5.1.3.1 Schuylkill River 5.1.3.1.1 Intake Operation of the LOS cooling water intake will affect some aquatic biota through impingement and entrainment. Some organisms too large to pass through the 6-mm mesh traveling fs screens will become impinged and disposed of with the trash. It I\ ,) is assumed that smaller organisms that pass through the intake screens will suffer 100% mortality as a result of extended exposure to temperature differentials and physical and chemical

~

stresses within the cooling system.

For purposes of impact evaluation it is assumed that at the annual average withdrawal rate, approximately 2.6% of river flow will be used at mean flow (50.2 m /s), 9.3% at 7-day, 10-year low l

flow (7.0 m /s), and 27.2% at lowest recorded flow (2.4 m /s).

' Information derived from 316(b) studies conducted at Cromby (CGS, i 13 km downstream of LGS, PECo (Ref 5.1-5), Barbadoes (BGS, 40 km L downstream, PECo (Ref 5.1-6), and Schuylkill (SGS, 67 km i downstream,fPECo (Ref 5.1-7) Generating Stations.is presented

( where applicable.

a. Impingement j Large invertebrates and juvenile and adult fish will be j impinged. The number of organisms impinged is largely a l

function of intake location (as related to the variety I

and distribution of nearby fauna) and design. An intake not located in an area of high macroinvertebrate and fish density, and withdrawing a relatively small volume of water at low velocity, generally has a low potential for deleterious impingement impact (USEPA:p. 19 Ref 5.1-8). Based on these criteria the Schuylkill

[)

N- intake is not likely to impinge large numbers of macroinvertebrates or fish.

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i 5.1-5 Rev. 2, 12/81 l

I

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f LGS EROL Macroinvertebrates: Several important macroinvertebrates (crayfishes, Cambarus bartoni and Orconectes spp.; snails, Goniobasis v_irginica; and leeches, Erpobdella punctata) are large enough ( 6 mm) to be impinged. However these are benthic dwelling organisms which were never collected in drift samples near LGS (Section 2.2.2.1.6). Thus it is highly unlikely that a significant number of these organisms will be impinged. Crayfish were impinged at CGS, BGS, and SGS, but only one at each station.

Fish: The intake location is not an area of concentrated abundance for any important fishes (Section 2.2.2.1.7), and rare, endangered, or commercially valuable species do not presently inhabit this reach of the Schuylkill. American shad may be restored to the river during the life of the plant (Section 2.2.2.1.7). Striped bass and other migratory species could also be re-established, or in the case of the American eel become more abundant, when fish passages are constructed at downstream dams.

Fish passage facilities have been installed at Fairmount Dam.

Spawning, localized migration, and feeding of resident fishes take place in the general intake location, but the area is not of unique importance for these activities. In addition the area is only lightly utilized for sport fishing (Harmon, Ref 5.1-9).

The following operational and design features will help minimize entrapment and impingement of fishes: (1) the volume of water withdrawn (Section 3.3) will be small relative to total river flow, (2) at average (0.56 m /s) and maximum (0.70 m /s) blowdown, design approach velocities to the screens will be 0.13 and 0.16 m/s, respectively, under low flow (7-day, 10-year) clean screen conditions, (3) the face of the traveling screens will be set nearly flush with the river bank and preceded only by trash racks, so that lateral passage and stream flow may assist fish to escape, and (4) no curtain or skimmer wall (commonly a significant contributor to impingement) will be used.

The differences in elevation of the river bottom, front foot wall, and interior structure floor will create a pool about 1.7 m deep immediately in front of the traveling screens (Figure 3.4-9). This pool may attract and concentrate fish which increases the potential for impingement. Impinged fish that are carried up on the screens will be deposited in a trash receptacle.

Rates of impingement will vary among species. Fishes that migrate or undertake frequent localized movements are generally more susceptible to impingement than sedentary species. The catadromous American eel and anadromous American shad (if restored to the river) are both likely to migrate upriver and downriver past LGS. However, studies at power plants on the nontidal portion of the Delaware River (Lofton, Ref 5.1-10) have indicated that neither juvenile nor adult shad nor eels are frequently impinged from free-flowing waters, and the 316(b) studies at CGS and BGS on the Schuylkill River indicated few eels Rev. 2, 12/81 5.1-6

LGS EROL

( ) were impinged. The majority of fish impinged at CGS

• sere brown bullheads and white suckers. Most were collected in spring, probably as a result of localized spawning movements. It is probable that a similar situation will occur at LGS. Goldfish, brown bullheads, and pumpkinseeds exhibited considerable movement near LGS. The redbreast sunfish does not move frequently or far enough to cause serious movement related impingement, but due to its high abundance is likely to be regularly impinged. At CGS and BGS swallowtail shiners and spotfin shiners were infrequently found in impingement collections; banded killifish and tessellated darters were not collected. However it is difficult to determine whether these species actually avoid impingement, or, due to their small size, are entrained.

Fish impingement at LGS is expected to be below that recorded at CGS (11,199 fish impinged per year) and BGS (3319) because of the improved intake design at LGS. LGS intake capacity is only 15%

and 41% of that at CGS and BGS, respectively. LGS design intake average velocity is approximately one-third that at CGS and BGS.

b. Entrainment Drifting phytoplankton, zooplankton, benthic macroinvertebrates, and fish eggs and larvae will be entrained by the LGS intake. Weekly withdrawal

(~N projections summarized in Table 5.1-2 were used to

( , / estimate entrainment. It is assumed that all drifting biota, except fish eggs and larvae, are uniformly distributed in the Schuylkill, and that entrainment loss will be proportional to water withdrawn. Fish eggs and larvae were not uniformly distributed in the river near LGS (Section 2.2.2.1.7); and therefore loss of these organisms was estimated from densities within the portion of water withdrawn.

Phytoplankton and Zooplankton: The effects of entrainment on phytoplankton and zooplankton near LGS are expected to be minimal because (1) the proportion of river flow withdrawn will be low, (2) population densities near LGS are known (phytoplankton) or presumed (zooplankton) to be low (Sections 2.2.2.1.2 and 2.2.2.1.5), (3) most phytoplankton in the Schuylkill is dislodged periphyton which continually enters the water column due to scouring action, and (4) both components typically have high reproductive rates.

Macroinvertebrates: Most important macroinvertebrate species rarely drift (Section 2.2.2.1.6). For those that do, only a small proportion of the benthic population drift at any one time (Table 2.2.2.1-14). Furthermore, withdrawal of river flow and subsequent loss of drifting macroinvertebrates will be low (Table

/

s 5.1-3). Therefore entrainment of drifting macroinvertebrates is

) expected to have little impact on either local macroinvertebrate

/ populations or fish which feed on macroinvertebrate drift.

5.1-7 Rev. 2, 12/81 l-

LGS EROL Fish: Important species (Section 2.2.2.1.7) which reproduce in the Schuylkill near LGS either construct nests or broadcast adhesive eggs. As a result, few eggs enter the water column, and based on 1975 and 1976 spawning season data, only a small percentage of such eggs are expected to be withdrawn (Table 5.1-4).

It has been suggested that larval fish drift in streams is an important dispersal mechanism which prevents overcrowding of nursery habitat and enhances larvae survival (Nikolsky: p. 250, Ref 5.1-11; Dovel: p.13, Ref 5.1-12 ) . Because most drifting larvae near LGS are alive entrainment will add to natural mortality. However, neither dispersion nor mortality will be significantly affected due to the relatively low percentage of larvae withdrawn. Consequently, entrainment of eggs and larvae is not expected to seriously alter species composition or density of important species near LGS. In 1975 and 1976, taxa which hypothetically would have suffered thc greatest losses under normal station operation were those that drifted in greatest density along the intake shore (Table 5.1-4), but losses incurred during the entire spawning season would not have been of sufficient magnitude to significantly affect adult population numbers.

Some fishes larger than larvae but smaller than the size at which impingement occurs will be entrained. Limited knowledge of the distribution and behavior of juvenile fishes makes evaluation of this potential impact difficult. However, as with entrainment of larvae, the small proportion of river water withdrawn should preclude a significant impact.

5.1.3.1.2 Thermal Discharge The thermal discharge will meet criteria outlined by the Delaware River Basin Commission (Section 5.1.1.1). Estimated monthly average blowdown temperatures can be as much as 11.1 C above ambient (Table 5.1-1). However, the diffuser (Section 5.1.2) will promote rapid mixing, and only a slight increase ( l C) above ambient will occur after full mixing with one-third of the

, river. For purposes of the following impact evaluations, it was I

assumed that temperature decrease within the mixed area (46 m wide x 92 m long) will be proportional to distance from the diffuser pipe. Contact time for organisms drifting through this area will be approximately 1 and 5 minutes at river velocities of 152.5 and 30.5 cm/s, respectively (Section 5.1.2).

Phytoplankton, Periphyton, Macrophytes, Zooplankton, Macroinvertebrates: Drifting phytoplankton, zooplankton, and macroinvertebrates that pass over the discharge structure will be subjected to a temperature change. However an adverse effect is unlikely because of the relatively small temperature change and short contact time. Periphyton, macrophytes, and sedentary benthic macroinvertebrates downriver of the diffuser pipe will be Rev. 2, 12/81 5.1-8

LGS EROL (p)

in constant contact with the discharge. With the exception of a small area immediately downriver of the discharge, no measureable change in community structure or productivity is expected because of the small temperature difference.

Fish: Effects of thermal discharge on fish populations are expected to be minor and generally limited to a small area in the vicinity of the diffuser. Under no condition will the discharge pose a block to migrating anadromous fishes. Drifting larvae and downstream moving adults which pass through the discharge area will be subject to temperature change, but because of the rapid transit time and small temperature difference, no mortality is ,

expected. Temperatures near the diffuser will occasionally exceed upper avoidance levels for important species (Tables 5.1-5 and 6). Some displacement of fish from the immediate area may occur. During most of the year temperatures near the diffuser will be attractive to some species (Table 5.1-7). Fish attracted to the discharge will also have increased contact time with other blowdown constituents (Section 5.3). The impact of individual reactions to the altered thermal regime will be minor at the population level because of the small area involved.

In the event of rapid plant shutdown, fish near the diffuser may be subject to a drop in temperature of up to 11.1*C (20*F) (see Table 5.1-1). The effect of temperature change depends on the

(~ rate and magnitude of the temperature decline. The small

(_-}- discharge volume and the small delta T values (Tables 3.3-1 and 5.1-1) outside of the 0.4-ha mixing area indicate the potential for significant impact due to cold shock is small.

5.1.3.2 Perkiomen Creek 5.1.3.2.1 Diversion Low flow in summer and fall may be a problem in Perkiomen Creek, especially in dry years. Low flow stresses biota by reducing wetted area, velocity, depth, and often cover (Johnson Ref 5.1-13). Flow augmentation, especially during the low flow period of dry years, should improve aquatic habitat in Perkiomen Creek between the East Branch confluence and the Graterford intake (3.9 km), and thereby result in a slight increase in productivity of periphyton and benthos if newly wetted areas are submerged long enough for colonization. A reduction in densities of drifting biota may occur initially and throughout diversion if production is not proportional to flow augmentation. Flow augmentation is not expected to cause changes in species composition. Flow augmentation plus natural flow will fall within the natural range of flow variation presently experienced.

The unlikely event of a complete interruption of diversion flow (i.e., accidental pump shutdown) would cause a temporary (fw) reduction in abundance of some biotic components in low flow years. Populations will recover following resumption of 5.1-9 Rev. 2, 12/81

LGS EROL augmentation, the rate depending on the population affected, the time of year, and the duration of interruption. The redundancy

{ of the power supply to the pumping station, pumping capacity, and the provision of emergency storage at Bradshaw Reservoir should essentially preclude a complete interruption. The introduction of new species via flow augmentation is possible and is discussed in Section 5.1.3.3.

5.1.3.2.2 Intake l l

A general discussion of intake effects on aquatic biota is given in Section 5.1.3.1.1. Due to constraints placed on the use of water from Perkiomen Creek (Section 2.4.1), operation of the Graterford intake and subsequent impacts to biota will be limited generally to the period April through November. Specific operating times will vary among years, depending on water flow.

At average withdrawal (1.5 m /s) a relatively large portion of water will be withdrawn; 16.0% of average flow (7.9 m /s, April-November) plus diversion, 75.0% of 7-day, 10-year low flow (0.5 m /s) plus diversion, and 93.8% of lowest recorded flow (0.1 m /s) plus diversion. In addition, occasions will arise infrequently when water can be withdrawn from Perkiomen Creek without augmentation; at average withdrawal under these conditions, a maximum of 26% of flow would be withdrawn.

The intake represents latest technology and will consist of a cylindrical wedge-wire screening system (Johnson screen, Section 3.4). The intake screens will be located in the center of the creek parallel with flow and will remain submerged even at extreme low flow. At maximum withdrawal (1.84 m /s) average velocity through the 2-mm screen slots will be 0.13 m/s; the maximum velocity will be 0.14 m/s.

a. Impingement Few macroinvertebrates and juvenile and adult fishes are expected to be impinged.

Macroinvertebrates: Intake operation is expected to affect only

subsurface drift. Chironomidae, Hydropsyche, Cheumatopsyche,

! Baetis, and Naididae (Oligochaeta) were most abundant in drift j

(Section 2.2.2.2.6) and therefore are subject to greatest impact.

Losses due to inpingement and entrainment are difficult to separate because many aquatic macroinvertebrates exceed 2 mm in length or width. Based on worst case condition 3 (100% mortality of all entrained and impinge 1 organisms), and using the average predicted withdrawal rate of 1.5 m /s, daily impingement plus entrainment loss was estimated for each of the 24-hour drift studies conducted in the immediate vicinity of the proposed Rev. 2, 12/81 5.1-10

( _ _ _ _ _ _ - - - - - -

LGS EROL 5.1-66 Coutant, C. C., " Compilation of Temperature Preference Data", Journal Fishery Resources Bulletin of Canada 34 (1977) pp. 739-745.

5.1-67 Ferguson, R. G., "The Preferred Temperature of Fish and Their Midsummer Distribution in Temperate Lakes and Streams", Journal Fishery Resource Bulletin of Canada, 15 (1958) (Original not seen) pp. 607-624.

5.1-68 Fry, F. E. J., " Effects of the Environment on Animal Activity", University of Toronto Study Biology Ser. 55, Publ. Ont. Fish. Res. Lab. 68, (1947) (Original not seen) pp. 1-62.

5.1-69 Hile, R., and C. Juday, "Bathymetric Distributions of Fish in Lakes of the Northeastern Highlands, Wisconsin,"

Trans. Wis. Acad. Sci. Trts Lett. 33 (1941), (Original not seen) pp. 147-187.

5.1-70 Horak, O. L., and H. A. Tanner, "The Use of Vertical Gill Nets in Studying Fish Depth Distribution, Horsetooth Reservoir, Colorado," Trans. Am. Fish. Soc.

93, (1964) pp. 137-145.

5.1-71 Reutter, J. M., and C. E. Herdendrof, " Laboratory O Estimates of the Seasonal Final Temperature Preferenda of Some Lake Erie Fish," Proc.17th Conf. Great Lakes Res. 1974 (1975), (Original not seen) pp. 59-67.

5.1-72 Reynolds, W. W., and J. B. Covert, " Behavioral Fever in Aquatic Extothermic Vertebrates" in Karger and Basel, eds. Drugs, Biogenic Amines, and Body Temperature, Proc. 3rd Int. Symp. Pharmacol. Thermoreg., Banff Alberta, 14-17 Sept. 1976, (1977) (Original'not seen).

5.1-73 Roy, A. W., and P. H. Johansen, "The Temperature Selection of Small Hypophysectomized Goldfish Carassius auratus L.)", Canadian Journal of Zoology 48 (1970) pp. 323-326 (Original not seen).

5.1-74 Scott, W. B. and E. J. Crossman, " Freshwater Fishes of Canada", Bulletin 184, Fishery Resource Bulletin of Canada.

5.1-75 Parr, A. D., and Sayre, W. W., " Prototype and Model Studies of the Diffuser Pipe System for Discharging Condenser Cooling Water at the Quad Cities Nuclear.

Station", IIHR Report No. 204, Iowa Institute of-Hydraulic Research, Iowa City, Iowa, June 1977.

O J

'5.1-41 Rev. 2, 12/81

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LGS Eh0L TABLE 5.1-1 (Page 1 of 3)

AVERAGE THERMAL DISCHARGE CHARACTERISTICS DURING FULL-POWER OPERATION Cooling Tower Blowdown Temperature 50% Exceedance Schuylkill Temperature Tempera ture River Dif f user Difference Rise 50 ft Heat Load Flowrate Flow Dilution Blowdown- Downstrean Discharged Month _JcisL___ _(MGD=C FS ) Factor Eiver ( O Fj_, _in River (0f1.

JgU/ho_uEl Jan 2244 20.3 = 31. 4 0.042 61-42 = 19 0.8 134 x 106 Feb 2457 20.3 = 31. 4 0.038 61-41 = 20 0.8 141 x.106 Mar 3217 18.3 = 28.3 0.026 65-48 = 17 0.4 108 x 106 Apr 2900 16.1 = 24.9 0.026 70-53 = 17 0.4 95 x 106-May 2218 14.1 = 21. 8 0.029 76-63 = 13 0.4 64 x 106 Jun 1513 16.3 = 25.2 0.050 8 2-7 2 = 10 0.5 57 x 106 Jul 1243 16.3 = 25.2 0.061 84-76 = 8 0.5 45 x 106 Aug 1090 16.3 = 25.2 0.069 84-78 = 6 0.4 34 x 106 Sep 1080 16. 3 = 25. 2 0.070 79-72 = 7 0.5 40 x 106 Oct 1154 16.3 = 25.2 0.066 73-61 = 12 0.8 68 x 106 Nov 1701 17.7 = 27.4 0.048 66-53 = 13 0.6 80 x 106 Dec 2093 19.7 = 31.5 0.044 62-45 = 17 0.7 116 x 106

=__ _ __

- =-

Annual 1910 17. 3 = 2 6. 8 0.042 72-59 = 13 0.5 78 x 106 (1) 260 12.4 = 19.2 0.222 73-61 = 12 2.7 52 x 106 (1) Extreme condition with 7-day, 10-year low river flow of 260 cf s and limited diffuser flow occurring with October river temperatures and October cooling tower blowdown temperatures that are exceeded only 50, 5, 1% of time respectively. October temperature differences were selected because this month would be most likely to contain the combination of low flow and high temperature difference.

Rev. 2, 12/ 81 1

O O O LGS EEOL TABLE 5.1-1 (CONT' D) (Page 2 of 3)

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Cooling Tower Blowdown Tempergure 55 Exceedance Schuylkill Temperature Temperature River Dif f user Difference Rise 50 ft Heat Load Flowrate Flow Dilution Blowdown- Downstream Discharged Month _Jcis) _(MGD=CFS)

Factor River (OFL_ in_ River fall JBIU/hourt Jan 2244 20.3 = 31. 4 0.042 72-42 = 3 0 1.3 212 x 106 Feb 2457 20.3 = 31. 4 0.038 72-41 = 31 1.2 219 x 106 Mar 3217 18.3 = 2 8. 3 0.026 76-48 = 28 0.7 178 x 106 Apr 2900 16.1 = 24.9 0.026 82-53 = 29 0.7 162 x 106 May 2218 14.1 = 21. 8 0.029 86-63 = 23 0.7 113 x 106 Jun 1513 16. 3 = 2 5. 2 0.050 89-72 = 17 0.8 96 x 106 Jul 1248 16.3 = 25.2 0.061 91-76 = 15 0.9 85 x 106 Aug 1090 16.3 = 25.2 0.069 91-78 = 13 0.9 74 x 106 rap 1080 16.3 = 25.2 0.070 87-72 = 15 1.1 85 x 106 Oct 1154 16.3 = 25.2 0.066 83-61 = 22 1.4 125 x 106 Nov. 1701 17.7 = 27.4 0.048 80-53 = 27 1.3 166 x 106 Dec 2093 19.7 = 31.5 0.044 72-45 = 27 1.2 185 x 106 Annual 19 10 17. 3 = 2 6. 8 0.042 88-59 = 29 1.2 175 x 106 (1) 'G0 12.4 = 19.2 0.222 83-61 = 22 4.9 95 x 106 (1) Extreme condition with 7-day, 10 year low river flow of 260 cfs and limited diffuser flow occurring with October river temperatures and October cooling tower blowdown temperatures that are exceeded only 50, 5, 1% of time respectively. Octooer temperature differences were selected because this month would be most likely to contain the combination of low flow and high temperature difference.

Rev. 2, 12/ 81

O O O LGS EROL TABL E 5.1- 1 (CONT' D) (Page 3 of 3)

Cooling Tower Blourdown Temperature 15 Exceejange Schuylkill Temperature Tempera ture River Diffuser Difference Rise 50 ft Heat Load Flowrate Flow Dilution Blowdown- Downstream Discharged Month icfs) JMGD=CFS) Factor River (OFL_ in Biver (OfL JB10/hourt Jan 2244 20.3 = 31. 4 0.042 77-42 = 35 1.5 247 x 106 Feb 2457 20.3 = 31.4 0.038 77-41 = 36 1.4 -254 x 106 Mar 3217 18.3 = 28.3 0.026 80-48 = 32 0.8 203 x 106 Apr 2900 16.1 = 24.9 0.026 87-53 = 34 0.9 190 x 106 May 2218 14.1 = 21.8 0.029 90-63 = 27 0.8 132 x 106 Jun 1513 16.3 = 25.2 0.050 91-72 = 19 1.0 108 x 106 Jul 1248 16.3 = 25.2 0.061 94-76 = 18 1.1 102 x 106 Aug 1090 16.3 = 25.2 0.069 94-78 = 16 1.1 91 x 106 l

i Sep 1080 16.3 = 25.2 0.070 90-72 = 18 1.3 102 x 106 Oct 1154 16.3 = 25.2 0.066 85-61 = 24 1.6 136 x 10*

Nov 1701 17.7 = 27.4 0.048 83-53 = 30 1.4 185 x 106 Dec 2093 19.7 = 31.5 0.044. 79-45 = 34 1.5 233 x 106 l

Annual 1910 17. 3 = 2 6. 8 0.042 91-59 = 32 1.3 193 x 106 C*) 260 12.4 = 19.2 0.222 85-61 = 24 5.3 104 x 106 (1) Extreme condition with 7-day, 10 year low river flow of 260 cfs and limited diffuser flow occurring with October river temperatures and October cooling tower blowdown temperatures j that are exceeded only 50, 5, 1% of time respectively. October temperature differences were selected because this month would be most likely to contain the combination of low flow and high temperature difference.

Rev. 2, 12/81 l

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4 LGS EROL O OUESTION E240.3 (Section 2.4.2)

Table 2.4-7 and Figure 2.4-5 apparently have been based on records through 1967. We understand other incidents of low flow have occurred which may alter estimates of the low flow frequency

. characteristics of streams in the. site region. Accordingly, discuss the low flow characteristics of the Schuylkill River, Perkiomen Creek, and the Delaware River at Trenton through 1980.

RESPONSE

Response will be provided in the first quarter of 1982.

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!O E240.3-1 Rev. 2, 12/81

LGS EROL QUESTION E240.11 -(Section 5.1) 1 In section 5.1 two additional effects should be identified.

First,.the effects of plant water use on other users should be identified (and possibly cross references to other sections of 1

the ER). Secondly erosion and deposition effects of water intake and discharge should be considered.

RESPONSE

.' Delaware River Basin Commission Docket D-69-210-CP indicates that constraints on consumptive and nonconsumptive use of Schuylkill River water. identified therein are determined so as to protect water quality and water quantity below the Limerick Generating l Station in accordance with the Commission's regulations. Station

, water use is discussed in-Section 3.3.

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Erosion and deposition effects of intake and discharge structures are discussed in the responses to Questions E240.5, E240.14, and 4

E240.18.

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O E240.11-1 Rev.-2, 12/81

LGS EROL QUESTION E240.12 (Section 5.1.1)

Identify Department of Environmental Resources (DER) and Delaware River Basin Commission (DRBC) standards for receiving water that may differ. Indicate which standard you intend to comply with.

RESPONSE

Differences in specific water quality criteria for the revised version of the DER Standards (effective October 8, 1979) and DRBC Standards (revised May 24, 1979) are identified below:

PARAMETER DRBC CRITERIA DER CRITERIA Minimum dissolved oxygen 3.5 mg/l (24-hr. avg.) 5.0 mg/l (daily)

Maximum temperature 860F 870F Allowable pH range 6.5 - 8.5 6.0 - 9.0 Maximum phenol 0.02 mg/l 0.005 mg/l (phenolics)

Maximum fecal coliform 770/100 ml 200/100 ml (5/1 to 9/30) 2000/100 ml (rest of yr.)

Maximum TDS 133% of background 500_mg/l (monthly avg.)

4 750 mg/l (maximum)

In addition to the above parameters, there are criteria in the DRBC Standards for parameters that do not appear in the DER j Standards, and vice-versa.

The LGS effluent will achieve sufficient dilution with the receiving water to meet applicable DER criteria at the mixing

, zone boundary, as required. The effluent will also be J

sufficiently diluted to meet the applicable DRBC criteria at the confluence of the Schuylkill River with the Delaware River, as required by the standards.

O l E240.12-1 Rev. 2, 12/81

LGS EROL QUESTION E240.13 (Section 5.1.2)

Identify the range of initial blowdown dilution areas anticipated for the corresponding range of Schuylkill River flows that are likely to occur during plant operation.

RESPONSE

, This information has been added to Section 5.1.2.

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O E240.13-1 Rev. 2, 12/81

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LGS EROL QUESTION E240.15 (Section 5.1.2)-

Average monthly blowdown temperatures alone do not indicate the i range of temperature likely to occur during plant operation.

Provide your estimates of the extreme temperatures likely to occur during operation and indicate whether such temperatures are i likely to cause impacts such as being a constraint on plant operation.

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RESPONSE

Section 5.1.2 has been changed to clarify blowdown temperature t conditions. '

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E240.15-1 Rev. 2, 12/81

' LGS EROL O QUESTION E240.16 (Section 5.1.2)

Indicate the likelihood of the intake structure on Perkiomen Creek being inoperable due to flooding or erosion. Provide the l basis for your analysis.

RESPONSE

j It is not expected that the intake structure on Perkiomen Creek

! would be inoperable due to flooding or erosion. The elevation of I '

the operating floor of the intake structure is at elevation 130 feet MSL, which is above the 100-year flood level estimated

! for Perkiomen Creek at this location (El. 125.7 feet).

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In addition, a channel stabilization structure has been

constructed across the river channel downstream of the intake

! location, which will stabilize the river channel bottom at the-j intake.

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O E240.16-1 Rev. 2, 12/81

LGS EROL QUESTION E240.17 (Section 5.1.2)

Indicate the period of record used to estimate the percentage of diverted flow in Perkiomen creek described in Section 5.1.3.2.2, and, if necessary, update for data collected through 1980.

RESPONSE

i The period of record used to estimate the percentage of diverted '

flow in the Perkiomen Creek was June 1914 to September 1975.

Table 2.4-8 lists the long-term average monthly flows for the Perkiomen Creek used for the average withdrawal estimate. Five additional years of flow data (1976-1980) would not significantly change the EROL estimates.

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? E240.17-1 Rev. 2, 12/81

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QUESTION E240.19 (Section 5.1.2)

Estimate the increased flow risk to property along the east branch of perkiomen Creek due to diversion from the Delaware River, that is, provide an estimate of the increased likelihood of flooding due to high creek flows from diversions coincident with heavy precipitation.

RESPONSE

A stream flow gaging station to be located just downstream of the discharge of diverted Delaware River water into the east branch of the perkiomen Creek will initiate an alarm in the Limerick control room whenever a predetermined water level in the east branch is reached. This water level will be considerably below flood levels. Upon receipt of this alarm, the reactor control room operators will stop all pumping, and only the water remaining in the pipeline will drain into the creek. The pumps will not be restarted until the water level at the gaging station has subsided. Therefore, no increased likelihood of flooding due to i

high creek flows from the diversion coincident with heavy precipitation is anticipated.

Iy E240.19-1 Rev. 2, 12/81

/'N LGS EROL b

OUESTION E240.21 (Section 7.1)

Calculate the radiological consequences of a liquid pathway release from a postulated core melt accident. The analysis should assume, unless otherwise justified, that there was a penetration of the reactor basemat by the molten core mass, and that a substantial portion of radioactively contaminated suppression pool water was released to the ground. Doses should be compared to those calculated in the Liquid Pathway Generic Study (NUREG-0440, 1978). Provide a summary of your analysis procedures and the values of parameters used (sucn as permeabilities, gradients, populations affected, water use). It is suggested that meetings with the staff of the Hydrologic Engineering Section be arranged so that we may share with you the body of information necessary to perform this analysis.

RESPONSE

Accidental releases of radioactivity to groundwater could provide a pathway for public radiation exposure and environmental contamination. Consideration has been given to the potential environmental impact of this pathway for the Limerick plant. The

(,_) principal contributors to the risk are the core melt accidents.

(. / The theoretical penetration of the basemat of the containment building could release molten core debris and significant quantities of suppression pool water containing dissolved or entrained radionuclides to the strata beneath the plant. Then, after significant time delays, soluble radionuclides in this debris can be leached and transported with groundwater to downgradient domestic wells used for drinking or to surface water bodies used for drinking water, aquatic food, and recreation.

An analysis of the potential consequences of a liquid pathway release of radioactivity for generic sites was presented in the Liquid Pathway Generic Study (LPGS) (Ref. E240.21-1). The LPGS compared the risk of accidents involving the liquid pathway (drinking water, irrigation, aquatic food, swimming, and shoreline usage) for four conventional generic land-based nuclear plants and a floating nuclear plant, for which the nuclear reactors would be mounted on a barge and moored in a water body.

Parameters for the land-based sites were chosen to represent averages for a wide range of real sites and are thus typical, but represented no real site in particular.

Doses to individuals and populations were calculated in the LPGS without consideration of interdiction methods such as isolating the contaminated groundwater or denying use of the water. In the event of surface water contamination, commercial and sports 7m fishing as well as many other water-related activities could be i' 'j restricted. The consequences could therefore be largely economic or social, rather than radiological. In any event, the E240.21-1 Rev. 2, 12/81 m

LGS EROL individual and population doses for the liguid pathway range from fractions to very small fractions of those that can arise from the airborne pathways.

The discussion provided in this response is an analysis to determine whether the Limerick site liquid pathway consequences would be excessive when compared to land-based sites considered in the LPGS. The method consists of a direct scaling of the LPGS population doses based cn the relative values of key parameters characterizing the LPGS " river" site and the Limerick site. The parameters evaluated included amounts of radioactive materials entering the ground, groundwater travel time, sorption on geological media, surface water transport, aquatic food consumption, and shoreline usage.

Table E240.21-1 lists the major parameters from the LPGS and the comparable parameters for Limerick. The groundwater travel and decay times are based on the analysis included in Limerick FSAR Section 2.4.13 for the postulated radwaste tank failure. The potential worst pathway is via groundwater flow to the Schuylkill River, a distance of over 800 ft (244 m). Alternate flow paths to drinking water wells are longer and go against the groundwater potentiometric contours.

The hypothetical accident scenario assembled from information in the Reactor Safety Study, Appendix VII (Ref. E240.21-2) and the LPGS, Appendix A-3, indicates that several hours to days would be available from the time of accident initiation to the time of core melt through the basemat. Then the core and its heat would effectively plug the hole in the basemat for times up to a year, thus preventing the release of liquid to the groundwater. After this release pathway is established (assuming that the liquid has not already evaporated through the ruptured containment), thete would be, for Limerick, an additional delay of at least 3.28 years for the groundwater and over 666 years for the Sr-90 and Cs-137 radicactivity to travel to the river.

Conceivably, during these long periods of time, measures would be taken to either interrupt the core melt and trap the radioactive contaminants in the ground, or to implement interdiction methods downstream from the plant, The various means of interdiction are discussed in the LPGS, Appendix E.

However, even without interdiction, the amounts of Sr-90 and Cs-137 released to the river would be very small, and less than those calculated in the LPGS, due to the long decay times incurred during migration. These transport times are significantly longer than those assumed in the LPGS. The additional decay and subsequent smaller source term more than compensates for the larger population that could be exposed via the drinking water pathway. The eating-of-fish pathway is much Rev. 2, 12/81 E240.21-2

. -- - =.- . _ - = - . _ . . . . . _ - . - - _, __ _

l LGS EROL I

i less significant than that assumed in the LPGS study due to the lack of commercial fishing in the Schuylkill River.

REFERENCES E240.21-1. NUREG-0440, Liould Pathway Generic Study, USNRC, Washington, D.C., February 1978.

i E240.21-2. Reactor Safety Study, WASH-1400, An Assessment of Accident Risks in U.S. Commercial Nuclear Power

Plants, USNRC, 6ctober 1975.

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E240.21-3 Rev. 2, 12/81

LGS EROL TABLE E240.21-1 O

PARAMETER COMPARISON FOR LIQUID PATHWAY RELEASES FOLLOWING A CORE MELT LPGS, PARAMETER NUREG-0440 LIMERIC_K Source term basis (NUREG-0440, Table A-8) 3200 MWT 3458 MWT Groundwater velocity (m/ day) 2.04 0.2 Distance to surface water interface (m) 457 244 Groundwater travel time (yr) 0.61 3.28 Sr-90 effective mean transport time (yr) 5.7 666.6 Cs-137 effective mean transport time (yr) 51. >666.6 Surface drinking water population 6.2x105 1.9x10*(2)

Annual fish harvest (Kg) 1.2x106 4.5x10* h (2) Drinking water for the remainder of the Philadelphia population comes from the Delaware River and several reservoirs not affected by a postulated accident (ER Section 2.1.3.6).

O Rev. 2, 12/81 E240.21-4

p LGS EROL G

OUESTION E240.22 (Section 2.4.2)

Descriptions of floodplains, as required by Executive Order 11988, Floodplain Management, have not been provided. The definition used in the Executive Order is:

Floodplain: The lowland and relatively flat areas adjoining inland and coastal waters including floodprone areas of offshore islands, including at a minimum that are subject to a one percent or greater change of flooding in any given year.

a. Provide descriptions of the floodplains adjoining the Schuylkill River, Perkiomen Creek, East Branch Perkiomen Creek, and the Delaware River adjacent to the site, plant facilities and reaches used for carrying pumped diversion flow. On a suitable scale map (s) provide delineations of those areas that will be flooded during the one percent (100 year) flood both before and after plant construction or operation.

b. Provide details of the methods used to determine the floodplains in response to a. above. Include your s assumptions of and basis for the pertinent parameters used in the computation of the flood flows and water elevations. If studies approved by the Federal Insurance Administration (FIA) are available for the site and other affected areas, the details of the analysis used in the reports need not be supplied. You can instead provide the reports frem which you obtained the floodplain information.

c. Identify, locate on a map and describe all plant structures and topographic alterations in the floodplains. Indicate the start and completion dates of all such items.

RESPONSE

Response will be provided in the first quarter of 1982.

1 E240.22-1 Rev. 2, 12/81

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, LGS EROL OUESTION E240.23 (Section 2.4.2) 1 a) Discuss the hydrologic effects of all items identified in

! response to questions 240.22c. Discuss the potential for I altered flood flows and levels, offsite. Discuss the effects

! on offsite areas of debris generated from the site during

' flood events. l j b) Provide the details of your analysis used in response to a.

, above. The level of detail is similar to that identified in  !

l item 240.22b. .

RESPONSE

! i Response will be provided in the first quarter of'1982. l I

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E240.23-1 .Rev. 2, 12/81 1

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