Inventory of Radionuclides 

in Bottom Sediment of the 

Clinch River 

Eastern Tennessee

GEOLOGICAL SURVEY PROFESSIONAL PAPER 433-1

Prepared in cooperation with the 

U.S. Atomic Energy Commission and 

the Oak Ridge National Laboratory
Inventory of Radionuclides 

in Bottom Sediment of the 

Clinch River 

Eastern Tennessee

By P. H. CARRIGAN, JR.

TRANSPORT OF RADIONUCLIDES BY STREAMS

GEOLOGICAL SURVEY PROFESSIONAL PAPER 433-1

Prepared in cooperation with the 

U.S. Atomic Energy Commission and 

the Oak Ridge National Laboratory

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1969
UNITED STATES DEPARTMENT OF THE INTERIOR 

WALTER J. HICKEL, Secretary

GEOLOGICAL SURVEY 

William T. Pecora, Director

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 - Price 35 cents (paper cover)
CONTENTS

Abstract _ _ ________________

Introduction. _______________

Acknowledgments___ _______

Coring procedures and results.. 

Selection of sampling sites. 

Coring tools____________

Results of coring. ________

Core processing_____________

Computation of inventory. 

Results. _____________________

Inventory of identified radionuelides __ 

Estimate of accuracy of inventory.

II 

1

3

4

4

5

5

7

9

11

11

11

Results continued

Retention factors.______________________________

Distribution of radionuclides_____________________

Longitudinal distribution.___________________

Vertical distribution_______________________

Contribution to inventory from reaches outside of 

study reach__________________________________

Distribution of sediment..-_______________________

Physical properties____________________________

Future estimation of radionuclide loading-_____________

Conclusions._______________________________________

References.._______________________________________

112

13

13

14

14

15

16

16

17

18

ILLUSTRATIONS

FIGTJBE 1. Index map showing study area; low-level radioactive waste waters are released through Whiteoak Dam_ _____

2. Map showing 14 sampling sections in Clinch River___________________________________________________

3. Graph of sampling sections located in reaches of high, low, and transitional levels of radioactivity. _ __________

4. Graph of coring penetration, sample recovery, and distribution of sediment and of radioactivity at Clinch 

River mile 7.5__-_______________-______-____-____________-_________-_---__--___________-_-____

5. Photograph showing coring from barrel float-______________________________---_-_-_---_-_--_----____

6. Diagram showing scanner for detection of gamma radiation in core______________-___-_-__-__---______

7. Photograph showing masonry saw cutting frozen cores.______________________________________________

8. Diagram showing methods of determining length, width, and thickness of subvolumes____________________

9-14. Graphs:

9. Similarities in longitudinal distribution of radionuclides_______________________________________

10. Longitudinal distributions of cesium-137, determined through different sampling techniques, are much 

alike______________________________________________________________________________

11. Concentration bears a nearly direct relationship to sediment thickness___________________________

12. Sediment thickness in the downstream direction____________________________________________

13. Cross-sectional area of radioactive sediment-________________________________________________

14. Time required to accumulate 2.6 feet of sediment over a given proportion of surface area. ___________

12

4

4

8

8

10

13

14

14

15

16

17

TABLES

TABLE 1. Yearly discharges of radionuclides to the Clinch River________________________________________________ 13

2. Numbers of sampling sites, of samples used in computations, and of truncated cores used in computations for

each sampling section-_______________________________________________________________________ 7

3. Method of estimating depth of radioactivity of truncated cores collected in the Clinch River________________ 11

4. Quantity of total identified radioactivity and volume of radioactive sediment in subreaches_________________ 12

5. Areal distribution of radioactive sediments, for selected thicknesses.____________________________________ 16

in

TRANSPORT OF RADIONUCLIDES BY STREAMS

INVENTORY OF RADIONUCLIDES IN BOTTOM SEDIMENT OF THE CLINCH RIVER

EASTERN TENNESSEE

By P. H. CAKKIGAN, JK.

ABSTRACT

An inventory has been made of the radionuclides associated 

with bottom sediment in the lower Clinch River. The reach included in this inventory extends 21 miles from the mouth of 

the river to the mouth of Whiteoak Creek.

The source of the radionuclides in the sediments was the 

release of low-level-radioactive waste waters from the Oak 

Ridge National Laboratory into Whiteoak Creek basin and 

thence into the river via Whiteoak Lake.

Results of the inventory indicate that the following quantities 

of radioactivity were associated with the bottom sediment in 

July 1962: 150 curies of cesium-137; 18 curies of cobalt-60; 16 

curies of ruthenium-106; at least 10 curies of rare earths; and 

2.9 curies of strontium-90. Most of the radioactivity was found 

to be downstream from mile 15; about 95 percent of the identified radioactivity was in this reach. Maximum concentration 

of radioactivity occurred near the mouth of Whiteoak Creek.

A high proportion of cesium-137 (21 percent), rare earths 

(about 25 percent), and cobalt-60 (9 percent) released to the 

river are retained in bottom sediment of the study reach. Retention of ruthenium-106 and strontium-90 is minor--less than 1 

percent each.

INTRODUCTION

This report describes a contribution of the U.S. Geological Survey to the Clinch Eiver Study. The Clinch 

River Study was a multiagency effort to evaluate the 

past, present, and future use of the Clinch Eiver for disposal of low-level-radioactive liquid waste from the Oak 

Ridge National Laboratory, which is in eastern Tennessee (Morton, 1961, 1962b, 1963) and is operated by 

Union Carbide Corp. for the U.S. Atomic Energy Commission. The agencies that participated in the study are: 

Oak Ridge National Laboratory (ORNL); Tennessee 

Game and Fish Commission; Tennessee State Department of Public Health, Stream Pollution Control 

Board; Tennessee Valley Authority (TVA) ; U.S. 

Atomic Energy Commission (AEC); U.S. Geological 

Survey (USGS); and U.S. Public Health Service 

(PHS).

When the study was begun in 1960, the Clinch River 

Study Steering Committee, an advisory group composed of representatives of each of the participating 

agencies (Morton, 1963, p. 1) established the following 

objectives: (1) To determine the fate of radioactive 

materials currently being discharged to the Clinch 

River, (2) to determine and understand the mechanisms of dispersion of radionuclides released to the 

river, (3) to evaluate the direct and indirect hazards of 

current disposal practices in the river, (4) to evaluate 

the overall usefulness of the river for radioactive waste 

disposal purposes, (5) to provide appropriate conclusions regarding long-term monitoring procedures.

Work described in this report was part of a cooperative program with the Health Physics Division, ORNL; 

the Oak Ridge Operations Office, AEC; and the Division of Reactor Development and Technology, AEC.

The release of low-level-radioactive liquid waste to 

the basin of Whiteoak Creek, which drains the ORNL 

area, was begun soon after establishment of the Laboratory in 1943 for the processing of radioactive materials. 

Radioactive liquids have entered Whiteoak Creek as a 

result of direct releases of processed waste water from 

the Laboratory, seepage from liquid waste holdup pits, 

and drainage from solid-waste disposal trenches 

(Browder, 1959).

Throughout most of the Laboratory's history, the 

waters of Whiteoak Creek have been impounded in 

Whiteoak Lake by Whiteoak Dam, which is located 0.6 

mile upstream from the mouth of the creek. The lake 

was created as a holdup facility for the radioactive 

waste carried in the creek water. Radioactive waste 

waters in Whiteoak Creek flow into the Clinch River at 

a point 3.3 miles downstream from fche Laboratory area. 

The diluted wastes in the Clinch River flow into the 

Tennessee River 20.8 miles downstream from the entry 

of Whiteoak Creek.

The continuous release of radioactive wastes to the 

Clinch River during nearly 20 years of Laboratory operations has provided a unique opportunity for studying

II
12 TRANSPORT OF RADIONTJCLIDES BY STREAMS

the effects of such releases on the river and the effects of 

the physical, chemical, hydrologic, and biological 

characteristics of the river on the fate of the radioactive materials.

Since 1943 part of the radioactive materials released 

from OENL through Whiteoak Dam (fig. 1) have become associated with bottom sediment of the Clinch 

River.

First indications of association of radionuclides with 

riverbed sediment came from work by Garner and 

Kochtitzky (1956). They made measurements, annually, 

of levels of radiation from the surface of the bottom 

sediment in the period 1951-53. Continued observation 

of annual changes in longitudinal distribution of radioactivity in surface layers of Clinch River bottom sediment by Cottrell (1959) suggested that accumulation of 

radioactive sediment might be occurring.

In 1960, coring of the Clinch River bottom sediment 

was undertaken at selected sites to explore more fully 

the possibility of accumulation of radioactive sediment. Variations in vertical distribution of radioactivity in a few cores strongly implied accumulation of 

radioactive deposits in the riverbed (Carrigan and 

others, (1967).

Partial inventory (upper strata) of radionuclides in 

Clinch River bottom sediment, derived from analysis of 

the 1960 cores, showed that retentions in the sediment 

of cobalt-60, rare earths, and cesium-137 probably

7'30" 84°00'

TENNESSEE

_ - ''NORTH 

| CAROLINA

A Streamflow stations

1 Clinch River near Scarboro, Tenn.

2 Whiteoak Creek at Whiteofik Dam, 

near Oak Ridge, Tenn.

3 Whiteoak Creek below ORNL, 

near Oak Ridge, Tenn.

4 Whiteoak Creek at ORNL,

near Oak Ridge, Tenn. 

oWater-sampling station at mile 5.5

Enlargement

at right MELTON HILL 

DAM

10 MILES

FIGURE 1. Low-level-radioactive waste waters are released through Whiteoak Dam to the Clinch River, a tributary to the Tennessee River.
INVENTORY OF RADIONUCLIDES IN SEDIMENT, CLINCH RIVER, EASTERN TENNESSEE 13

TABLE 1. Yearly discharges of radfonuclides to the Clinch River

[Results in curies. Results of total rare-earth (TRE) analysis include yttrium-90 content but exclude cerium-144 content. From Cowser and Snyder (1966, p. 6)J

Year Gross 

beta

TRE Ce»« 1131

1Q4Q

1950___________.____.

1951__.__ ___..._____.

1952______. ______._..

1953___.___ _________

1954________________

1955________________

1956_. ______________

1957 _______________

1958____.___________

1959 __ _____________

1960________________

1961_________-______

1962________________

1963________________

71 8

------_________ 191

_______________ 101

_______________ 214

_______________ 304

°.P.4

_______________ 437

_______________ 582

--_-____.______ 397

.-_-___________ 544

_______________ 937

_______________ 2,190

_______________ 2,230

_______________ 1,440

_______________ 470

77

1Q

20

Q Q

6.4

22

63

170

89

55

76

31

15

5.6

3.5

110

OQ

18

1 P.

26

11

31

29

60

42

520

1,900

2,000

1,400

430

1 f»n

00

on

79

130

140

93

100

83

150

60

28

22

9.4

7.8

77

on

11 _

OR

110

160

150

140

110

240

94

48

24

11

9.4

1 8

oo

6.7

24

85

59

13

30

48

27

4.2

1.2

1.5

1801 P»

4. 5

1Q

7.6

14

5.2

12

23

6.0

27

38

20

2. 2

.34

22

42

2.2

18

3.6

9.2

5.7

15

7.1

6. 0

30

45

70

7.7

.71

77

19

18

20

2. 1 _.

3.5 _.

7.0

3.5

1.2

8.2

. 5

5.3

3.7

.36

.44

6.6

46

4.8

8.7

77

72

31

14

14

ranged from 10 to 20 percent of the quantity released 

from ORNL (table 1; see Carrigan and others, 1967). 

A complete inventory could not be made because the 

coring tool did not completely penetrate the radioactive 

sediment (Morton, 1962a, p. 45-60).

Based on results of the partial inventory, the proportions of cobalt-60, rare earths, and cesium-137 releases associated with the river bed deposits in 1960 

did not seem extraordinarily high. However, a complete inventory was needed to establish the quantity 

of radionuclides that had become associated with the 

bed deposits of the 21-mile-long study reach since 1943. 

Once the inventory was accomplished, the influence of 

the deposits on retention of these and other radioactive 

elements in the lower Clinch Kiver would be better 

understood.

Information from the inventory of the radionuclides 

in Clinch River bottom sediment was obtained to meet 

the first objective of the Clinch River Study (see "Introduction"). Also, the information is applied to meet 

objectives 3,4, and 5 of the study.

Data from this inventory may be applied to further 

refine safety analysis of current practices of radioactive waste disposal (third study objective; see Cowser 

and Snyder, 1966).

Estimates of the fraction of each radionuclide retained in the study reach may be used in forming a 

predictive model to evaluate the capacity of the Clinch 

River to safely receive radioactive liquid wastes (fourth 

study objective).

Techniques of collecting and analyzing samples, 

methods of ascertaining total quantity of radioactivity, 

and the accuracy of the inventory may suggest alternate 

or additional procedures that may be applied to longterm monitoring procedures (fifth study objective).

The bottom sediment was sampled by coring. Undisturbed cores were required in this inventory for use 

in measuring vertical distribution of the radioactivity 

in order to define the base of the radioactive zone

throughout the study reach. Once the radioactive length 

of the core was determined, analyses for radionuclide 

content could be made, mass and volume of radioactive 

sediments could be computed, and the quantity of radionuclides in the sediments could be inventoried.

Cores were collected from preselected sections, extending from near the mouth of the Clinch River upstream to Melton Hill Dam (fig. 2).

The cores, collected in the summer of 1962, were also 

available for use in other studies. Pickering (1969) 

made use of them in investigation of vertical distribution of radioactivity and of physicochemical properties 

of the sediment.

ACKNOWLEDGMENTS

Inventory of radioactivity in Clinch River bottom, 

sediment was financed by the Division of Reactor Development and Technology, AEC. A part of this financing was used for particle-size analysis at laboratories 

of the Water Resources Division, USGS, in Raleigh, 

N.C., and for a variety of services furnished through 

arrangements made by F. L. Parker, Health Physics 

Division, ORNL.

Services furnished at ORNL included a contract for 

coring with Sprague and Henwood, Inc., design and 

fabrication of the core scanner and the core saw, radiochemical analysis, use of a general purpose digital computer, laboratory technicians to assist in sample collection and in preparation of cores for physicochemical 

analysis, and consulting services.

Design and fabrication of the core scanner and core 

saw were by P. N. Hensley, Health Physics Division, 

and by C. D. Martin and W. F. Johnson, Instruments 

and Controls Division. Some radiochemical analyses 

were performed under the direction of C. L. Burros 

and J. H. Moneyhun, Analytical Chemistry Division. 

Advice in computer programing was given by M. T. 

Harkrider, R. P. Leinius, and A. M. Craig, Jr., Mathematics Division.
14 TRANSPORT OF RADIONUCLIDES BY STREAMS

EXPLANATION

pif' Sampling section; distance upstream from river mouth, 

' 3 in miles 

2 Distance upstream from river mouth, in miles

1 Vi 0

MELTON HILL DAM

1 MILE'

FIGURE 2. Fourteen sampling sections were established in the Clinch River, downstream from Melton Hill Dam.

Persons making special contributions to this investigation were R. J. Pickering, USGS, who supervised 

coring operations and continually furnished valuable 

and timely advice; E. Schonfeld, Chemical Technology 

Division, ORNL, who made available the computer 

program for gamma spectrum analysis and supervised 

computer processing of gamma spectrum data; and 

E. R. Eastwood, Health Physics Division, ORNL, who 

was the major assistant in field and laboratory work.

Data on annual monitoring surveys of radioactivity 

in bottom sediment of the Clinch and Tennessee Rivers 

were furnished by H. H. Abee and W. D. Cottrell, 

Health Physics Division, ORNL; data on channel bed 

profiles at sediment ranges were furnished by J. W. 

Beverage, Chief, Hydraulic Data Branch, TVA.

Many illustrations in this report were prepared by 

Graphic Arts, ORNL.

CORING PROCEDURES AND RESULTS

Coring verticals were areally spaced to sample both 

variations in (1) distribution of radioactivity and (2) 

volume of bottom sediment in the study reach. In selection of sampling sites, longitudinal variations in radioactivity and in sediment volume and lateral vard'ations'in 

radioactivity were taken into consideration. Little was 

known of the thickness of the radioactive sediment. 

Therefore, the coring tool was driven to the maximum 

depth possible with the equipment used; generally this 

depth was at the top of bedrock or at the top of inpenetrable soil lying below the sediment.

SELECTION OF SAMPLING SITES

Locations of sampling sections were based on the 

longitudinal pattern of radionuclide distribution in the 

study reach. Sections were selected to sample reaches 

of high and low radioactivity, locations at which breaks 

in the general trend of increasing or decreasing radioactivity occurred, and reaches of transition from one 

radiation level to another. Superposition of section location (fig. 2) on the longitudinal distribution pattern of 

radioactivity (Carrigan and others, 1967, p. 24) in 

figure 3 illustrates the relationship of location to variation in radioactivity.

The two sections established on the Emory River and 

on Poplar Creek (fig. 2) provided subsidiary information to health physicists at ORNL on possible upstream

? Data from 1960 

^monitoring survey

CLINCH RIVER MILE

FIGURE 3. Sampling sections were located in reaches of high, low, 

and transitional levels of radioactivity.
INVENTORY OF RADIONUCLIDES IN SEDIMENT, CLINCH RIVER, EASTERN TENNESSEE 15

movement of radioactive contaminants into streams 

tributary to the Clinch River.

Spacing of coring verticals within a sampling section was chosen by combined assessment of transverse 

distribution of sediment thickness and of radiation 

levels at the sediment surface. Relation of spacing of 

verticals to variations in these variables for one sampling section is shown in figure 4.

CORING TOOLS

The author and his associate, R. J. Pickering, USGS, 

selected the Swedish Foil Sampler as the primary sampling tool after having made inquiries to other investigators engaged in sampling of bottom sediments, particularly marine sediments, and after having searched 

the literature on coring equipment.

Within the barrel of the Swedish Foil Sampler (fig. 

5) are 16 steel foils (0.05 inch wide by 0.0005 inch thick) 

which completely line the barrel. The foils prevent friction between the sediment core and the walls of the 

barrel; as the sampler is pushed into the sediment, the 

foils unroll from coils stored in a magazine in the head 

of the sampler. Foils are pulled from the magazine because one end is affixed to a piston within the barrel; 

the vertical position of the piston is fixed at, or just

above, the sediment surface as the head and barrel of 

the sampler are pushed into the sediment.

Little or no compaction of sample apparently occurred in the use of the Swedish Foil Sampler. Recovery 

of cores was very satisfactory, especially if a basket shoe 

and a plastic sleeve were inserted as retainers in the 

sampler tip.

A more complete description of the sampler, its use, 

and results of its application is given by Pickering 

(1965).

The Swedish Foil Sampler could not be used in soupy 

sediments, in sandy sediments, and in sediments consisting mostly of pebbles and gravel. For soupy sediments, SCUBA divers drove a thin-walled, 2^-inch 

coring tube into the sediment. For sandy sediments, 

sampling was done with a split-barrel sampler, containing a basket shoe and a plastic sleeve for sample 

retention. Hand-operated clam-shell dredges were used 

to collect gravel samples.

RESULTS OF CORING

In the summer of 1962, cores were collected at 135 

verticals in 14 sections in the Clinch River and in 4 

sections in tributaries to the river (see fig. 2). The 

number of verticals in a section ranged from 4 to 13.

SEDIMENT SURFACE ACTIVITY

0 100 200

*(CPM)= COUNTS PER MINUTE

300 400 500 

DISTANCE FROM LEFT BANK, IN FEET

600 700 800

FIGURE 4. Coring-tool penetration, sample recovery, transverse distribution of sediment thickness and of surface radiation levels, and vertical distribution of gross gamma radioactivity at Clinch River mile 7.5 (from Pickering, 1969).

331-517
16 TRANSPORT OF RADIONUCLIDES BY STREAMS

FIGURE 5. Coring was done from a barrel float. Sampler head and part of the segmented barrel of the Swedish Foil Sampler are suspended

from drilling tower.
INVENTORY OF RADIONUCLIDES IN SEDIMENT, CLINCH RIVER, EASTERN TENNESSEE 17

Relationships 'between depth of penetration, length 

of core recovered, and thickness of the radioactive zone 

at CRM (Clinch River mile) 7.5, seen in figure 4, exemplify the success of coring operations generally experienced throughout the study reach. The abbreviation 

CRM followed by a number has been used in this report 

to designate distance, in miles, upstream from the mouth 

of the river. This terminology is consistent with prior 

usage in the Clinch River Study (Morton, 1961) .

Results of coring at each section are summarized in 

table 2. Two situations of special significance to the 

summary of coring results are emphasized by the table: 

(1) 15 cores did not completely penetrate the radioactive zone, and (2) not all cores or dredge samples 

were found to contain significant quantities of radioactivity in subsequent analyses. Therefore, samples containing no radioactivity were excluded from further 

direct consideration in computations.

TABLE 2. Numbers of sampling sites, of samples used in computations, and of truncated cores used in computations for each 

sampling section

[Length of truncated core recovered is less than thickness of radioactive zone]

Location of sampling

section (miles

upstream from

mouth)

Coring 

verticals

Dredge 

samples

Used in computations

Cores Dredge

samples

Truncated 

cores

Clinch River

1.3 

4.3 

7.5 

10.0______.__

11.9______.__

12.1 _ _____

14.0-________

16.0 _______

17.5_________

19.2 ___ _ _

20.5_________

20.8 1 __-____

21.0 __ -

22.8 ___ _ .

____ 10

_.__ 13

__ 9

____ 11

__ 11

_ __ 11

____ 5

_.__ 7

..__ 6

.____ 5

____ 8

,____ 5

.____ 4

5

0

0

0

0

0

0

0

0

0

0

6

7

0

1

8

12

9

10

10

11

5

7

6

4

8

3

2

5

0

0

0

0

0

0

0

0

0

0

6

7

0

1

3

3

1

2

1

3

0

0

0

0

1

1

0

0

Emory River

1.9- 

5.1.

Poplar Creek

3.1-

4.5_

> Section 100 feet downstream from mouth of Whiteoak Creek.

CORE PROCESSING

Core processing was divided into four major procedures : measurement of gross gamma radiation distribution, longitudinal cutting, preparation of composite 

samples for analyses, and physical and radiochemical 

analyses of composites. Until the final two processing

procedures were undertaken, the cores (and dredge 

samples) were frozen.

Cores were frozen shortly after collection for two reasons: (1) To suppress biological and chemical action 

and (2) to prevent distortion of the plastic cohesive 

samples.

The frozen cores, still wrapped in steel foil and encased in a plastic tube, were placed in a specially fabricated radiation-counting apparatus called a core scanner (fig. 6). The core scanner was used to automatically 

measure the gross gamma radiation in 2-inch increments 

along the full length of the core. For measurement of 

distribution of gross gamma radiation, the electrical 

output from the photomultiplier tube was routed to a 

sealer (Pickering, 1969).

Limitation of radiation detection to a 2-inch increment was improved by inclusion of a collimated detector 

in the core scanner. However, the length of the collimator channel (2-in.) was too short for precise collimation, 

and radiation from zones of core above and below the 

face of the collimator was detected. Through calibration 

of the instrument, effects of imperfect collimation on 

radiation measurements were corrected.

For accuracy and economy, the corrections due to imperfect collimation were applied to the counting data 

from the sealer by means of a computer program. Examples of the bar-graph plots, derived from the computer program and showing radiation distribution for 

2-inch incremental lengths of core, are given in figure 4.

Corrected counting data for each 2-inch-high slice of 

core were used to define the thickness of the radioactive 

zone at each core vertical (see fig. 4). These data were 

also used as a guide in determining cores in which there 

was no significant radioactivity.

After the counting of gross gamma radiation, each 

core was cut longitudinally into halves and one of the 

halves was divided longitudinally to provide a quartersection sample for use in the inventory and to provide 

duplicate samples for use by Pickering (1969) in his 

studies of vertical distribution of radioactivity and the 

physicochemical characteristics of the sediments. Cutting was done by placing the frozen core in a jig 

and passing the jig through a carbide-tipped circular 

saw (fig. 7). The quarter-section core cylinders used 

in this inventory were cut horizontally at the base of 

the radioactive zone, and the nonradioactive part was 

discarded.

After cutting, the volume and weight of the cylinder 

of radioactive sediment were measured for determination of specific bulk weight. The volume of the cylinder 

(including void space) was found by permitting the 

frozen material to melt in a calibrated vessel. For these 

volumetric measurements, voids in the sediment were 

assumed to be completely filled with water.
18 TRANSPORT OF RADIONUCLIDES BY STREAMS

Multichannel

analyzer

and punch

tape readout

Sealer 

and printed 

tape readout

4-in. lead 

shielding

3- by 3-in. Nal crystal and 

photomultiplier tube

- Stepping pulley 

mechanism

Stepping interval 

control

Core in 

plastic tube

2-by .2-by 2-in. 

collimator

FIGURE 6. Core is hoisted through well in core scanner for detection of gamma radiation. Electric output from photomultiplier of detector may be routed to sealer or analyzer (from Pickering, 1969).

FIGURE 7. A masonry saw was modified to cut frozen cores, Jig holding core rolled under saw blade between guides on table.
INVENTORY OP RADIONUCLIDES IN SEDIMENT, CLINCH RIVER, EASTERN TENNESSEE 19

Next, a homogeneous composite of the quarter-section 

cylinder was prepared by using an electrically driven 

eggbeater. Preliminary tests showed that sediments 

ranging from highly cohesive to noncohesiv© could be 

homogeneously mixed in 10 minutes.

A 1-gram aliquot was split from the composite for 

analysis of particle-size distribution at laboratories of 

the USGrS in Raleigh, N.C. Then, the remaining composite was weighed, dried at 100° C (Celsius), and reweighed to provide data for computation of the dryto-wet weight ratio of the composite.

The dry composite was split into aliquots for radiochemical analyses using a Jones soil splitter. A 100- 

gram aliquot (±0.01g) was prepared for gamma spectrum analysis, and a 20-50 gram aliquot was prepared 

for analyses of strontium-90 and trivalent rare-earth 

contents.

Radiochemical analyses for strontium-90 and trivalent rare-earth contents of the 20-50 gram aliquots 

were performed at the Low-Level Counting Facility, 

Analytical Chemistry Division, ORNL. Standard methods of chemical extraction of the specified elements and 

beta counting of the extracts were used in these analyses 

(Raaen and Cline, 1964).

Analysis of concentrations of cesium-13Y, cobalt-60, 

and mthenium-106 in composites of the bottom sediment 

was made by techniques of gamma spectrometry by 

using a sodium iodide crystal, 4 inches high by 4 inches 

in diameter, for a detector and by using a 512-channel 

pulse-height analyzer. Derivation of concentrations for 

the desired radionuclides from punch-taped data was 

obtained by means of a computer program which utilized a technique of least-squares resolution of the 

gamma-ray spectra (Schonfeld and others, 1965). Input data for the computer program included the spectra 

for the sample, the background associated with the sample, and known concentrations of selected radionuclides 

(standards). Standards were selected on the basis of 

records of releases of radionuclides from Whiteoak 

Lake, experience from other investigations of radioactivity in bottom sediments (see Cottrell, 1959; Carrigan and others, 1967), and the knowledge that naturally occurring radionuclides are found in soil and 

rock of the area. Standards included were cesium-137, 

cobalt-60, ruthenium-106, cerium-144, zirconium-95, 

niobium-95, cesium-134, europium-152, europium-154, 

potassium-40, uranium ore, and thorium ore.

To assure that results of radionuclide analyses by 

gamma spectrometry were reasonably accurate, nine selected samples were reanalyzed at the Low-Level Counting Facility, ORNL. These samples were selected as 

representative of the general range of radioactivity and 

of sampling location for samples collected throughout

the study reach. Analysts at this facility found that concentrations of only two radioactive contaminants, 

cesium-137 and cobalt-60, could be reliably determined 

by their method of hand computation of gamma spectra 

data produced from their pulse-height analyzer. Results 

for concentrations of cobalt-60 and cesium-137 determined by these analysts were slightly greater than those 

determined by computer program 7.8 and 13.8 percent 

greater, respectively.

Differences in results between computer and hand 

processing of counting data are believed logical; but the 

computer-derived concentrations are considered to be 

most accurate. Methods of hand computation do not appear to be sufficiently sensitive and precise to detect, or 

to compensate for, the presence of minor constituents 

in a sample if the concentrations of these constituents 

are 100 or more times less than concentrations of major 

constituents.

Cores presumptively containing no radioactivity 

based on results of gross gamma core scanning were 

reevaluated by careful examination of results of gamma 

spectra analyses for cesium-137 and cobalt-60 contents. 

Cores which contained concentrations of these radionuclides slightly greater than limits of detection were 

included in the inventory.

COMPUTATION OF INVENTORY

The volume of radioactive sediments is divided into 

subvolumes when computing the inventory. The quantity of a radionuclide in a subvolume is equal to the 

product of its concentration (curies per unit weight) 

and weight of sediment in the subvolume. Total quantity of the radionuclide in the study reach is the sum 

of its quantities in the subvolumes.

Locations of sampling sections and of coring verticals 

in the study reach serve as controls for dividing the 

volume of sediment into subvolumes. Each subvolume 

is associated with a specific coring vertical.

Shape of each subvolume is assumed to be prismatic; 

its length extends from midpoints between adjacent 

sampling sections; its width extends from midpoints 

between adjacent coring verticals in the sampling section ; and its depth is equal to the thickness of the radioactive zone for the specified core. These definitions of 

dimensions of a subvolume are modified for the two 

terminal subreaches and for terminal verticals (where 

thickness of sediment is zero) in a sampling section.

The length of the terminal subreach for subvolumes 

associated with the sampling section at CRM 1.3 extends 

from CRM 0.0 to the midpoint between CRM 1.3 and 

4.3. The length of the terminal subreach for subvolumes 

associated with the sampling section at CRM 21.0 extends from the midpoint between CRM 20.8 and 21.0 to
110 TRANSPORT OF RADIONUCLIDES BY STREAMS

OEM 21.0. The widths of radioactive zones in the sampling sections did not extend in every case from one 

edge of water to the other. Hence the transverse locations of 'at least two, and sometimes more, terminal verticals of radioactive zone(s) in a section had to be defined. 

These terminal verticals were defined on the basis of 

(1) locations of cores that contained no detectable radioactivity, (2) rates of change of the gamma radiation 

levels at the surface of the 'bottom sediment, (3) rates of 

change in thickness of the radioactive zone, (4) transverse slope of the streambed, and (5) limits of bedrock 

areas as determined by probing of the bed material. The 

influence of some of these factors on location of terminal 

verticals is indicated in figure 4.

PLAN VIEW OF REACH IN VICINITY OF SECTIONS A.B.AND C

= length of subreach associated with sampling section B

ELEVATION VIEW OF PART OF SECTION B IN VICINITY OF 

CORING VERTICALS 3, 4, AND 5

t4 =thickness of subsection associated with 

coring vertical 4

fa< =width of subsection = V2 (63^ + fa 4_5 )

FIGURE 8. Methods of determining length, width, and thickness of 

subvolumes.

The width of the subvolume associated with a coring 

vertical adjacent to a terminal vertical was computed 

in the same manner as widths of other subvolumes.

A diagram of the methods of determining length, 

width, and thickness of subvolumes is shown in figure 8.

Sediment weight in a subvolume is the product of its 

volume and of the specific bulk weight and dry-to-wet 

weight ratio of its associated core. Specific bulk weight 

is the wet weight per unit volume. Equations for 

computations are as follows:

Vs=xbt 

in which Vs= volume of subvolume in cubic meters,

x= length of subreach in meters,

6= width of subvolume in meters, and

t thickness of radioactive zone in meters.

in which V total volume of radioactive sediment in 

study reach in cubic meters.

in which Ws=weight of sediment in sub volume in grams, 

ovendry basis,

s=specific bulk weight in grams per cubic 

meter, wet-weight basis, and

 ^= dry-to-wet weight ratio. 

RS=CWS

in which Rs=quantity of radionuclide in subvolume in 

picocuries (10~12 curies),

C= concentration of radionuclide in composite in picocuries per gram, ovendry basis.

Cx=

in which Cx= mean concentration of radionuclide in 

sampling section in picocuries per gram.

in which R total quantity of radionuclide in study 

reach in picocuries.

" B

in which tx= average thickness of radioactive sediment 

at sampling section in meters.
INVENTORY OF RADIONTTCLIDES IN SEDIMENT, CLINCH RIVER, EASTERN TENNESSEE 111

B total width of radioactive zone at sampling 

section in meters.

in which Ax= cross-sectional area of radioactive zone at 

sampling section in square meters.

Computations using these equations were facilitated 

through use of a general purpose digital computer. All 

dimensional units were converted to those commonly 

used in American engineering practice for presentation 

of results.

As shown in table 2, the recovered length of some 

cores was less than the thickness of the radioactive zone ; 

these cores are termed truncated. Thicknesses of radioactive sediment for truncated cores and dredge samples 

were estimated as follows: Distribution patterns of 

gross gamma radiation were discernable in many truncated cores; patterns of radioactivity distribution in 

such cores were compared to patterns for cores which 

penetrated the entire radioactive zone at nearby coring 

verticals; comparisons were made using correlation 

analyses developed in study of vertical distribution of 

radioactivity (Pickering, 1969) ; from results of these 

comparisons, the depth to which radioactivity extended 

could be estimated for truncated cores.

In some instances the truncated length was too short 

to clearly discern the distribution pattern of radioactivity, in which case the radioactive thickness at the 

coring vertical was assumed to be equal to the depth of 

penetration of the coring tool. Fortunately, the fraction 

of core recovered was large in most cases.

The scope of the adjustment procedures is summarized in table 3.

TABLE 3. Method of estimating depth of radioactivity of truncated 

cores collected in the Clinch River

[Length of truncated core recovered is less than thickness of radioactive zone]

Number of Adjustment based on depth of

Location of sampling section cores adjusted coring-tool penetration (miles upstream from mouth) through 

correlation ' Number Length of ratio 2

of cores

1.3 .______ .

4.3 _ ------

7.5 ___-___ 

10.0-_________-__.

11.9 ______ __.

12.1... ___________

20.5__-_-__. ______

20.8- ____ 

______ 2

.-_--_ 1 __.

.-____ 2 __.

.----_ 1 __.

______ 1

1

3

2

1

1

0 75

0. 67, 0. 74, 0. 82

0. 42, 0. 68

0.50

0. 73

1 Adapted from results of work by Pickering (1969).

* Ratio of truncated length to depth of penetration (radioactive length).

Approximately 2 years elapsed between collection and 

radiochemical analyses of cores. During this period, 

decrease in radioactive content through the process of 

radioactive decay was appreciable for some radionuclides. Concentrations used in the computations were 

adjusted to those at the time of sampling, except for 

rare earths. No adjustment for radioactive decay of 

rare earths was made because they are a mixture of 

radionuclides having a variety of radioactive half lives. 

Methods of adjustment for effects of radioactive decay 

on radiation have 'been described by the U.S. Public 

Health Service (1960).

Depth of penetration of hand-operated dredges could 

not be measured. Depths were computed by using 

information on volume of sample collected and on geometric characteristics of the sampler. Computed depth 

of sampling was assumed to be the radioactive depth.

RESULTS

In the course of acquiring necessary data to inventory 

radioactivity in Clinch Eiver bottom sediment, information has been gathered not only on quantities of 

radionuclides in the sediment but also on distribution 

of radionuclides in these sediments and distribution of 

the sediments in the river.

INVENTORY OF IDENTIFIED RADIONUCLIDES

The following quantities of radionuclides are associated with bottom sediments of the Clinch Eiver between GEM 0.0 and 21.0 : 150 curies of cesium-137, 18 

curies of cobalt-60, 16 curies of ruthenium-106, at least 

10 curies of rare earths, and 2.9 curies of strontium-90.

All quantities have been adjusted for effects of radioactive decay to those quantities present at the time of 

sampling (July 1962), except for the rare earths (see 

"Computation of inventory"). Quantity of rare earths 

reported is that present at the time of radiochemical 

analysis.

Total inventoried and identified radioactivity is 200 

curies, of which cesium-137 constitutes 77 percent; 

cobalt-60, 8.7 percent; ruthenium-106, 7.7 percent; rare 

earths, 5.1 percent; and strontium-90, 1.5 percent.

About 95 percent of the identified radioactivity is in 

the reach of river downstream from CEM 15 (table 4) . 

At least 50 percent of the identified radioactivity is 

downstream from CEM 8.7.

ESTIMATE OF ACCURACY OF INVENTORY

The quantity of a radionuclide in a volume of sediment, R, may be expressed by the equation

ww

in which the independent variables are, respectively, 

concentration of a radionuclide, length of subreach, 

width of sampling section, mean thickness of radioactive sediment in sampling section, specific bulk 

weight, and dry-to-wet weight ratio. The following
112 TRANSPORT OF RADIONUCLIDES BY STREAMS

expression is used to compute the level of expected error 

in R:

in which <rR is the standard deviation for R, vz is the 

standard deviation for each independent variable Z,

and -y is the relative error, or coefficient of variation,

forZ.

The relative error in the measurement of physical 

properties which appear in the above equation has been 

estimated by comparing the precision in measuring each 

property to the magnitude of the property. Errors in 

measuring specific bulk weight and dry-to-wet weight 

ratio are less than 5 and 2 percent, respectively. Kelative 

errors in dimensions of sediment volume have been estimated for each subreach downstream from CKM 15. 

Limitation in considered reach length has been made 

because 95 percent of the radioactivity is downstream 

from CRM 15. Coefficients of variation for subreach 

length, width, and thickness are about 3, 5, and 15 percent, respectively. Other independent sources of error 

in the determination of radionuclide concentration are 

accuracy of radionuclide standards, counting errors in 

analysis, and sampling errors. Error in radionuclide 

content of standards is about 5 percent. Average levels 

of counting errors for cesium-137, cobalt-60, ruthenium106, strontium-90, and rare earths are 2, 8, 23, 4, and 2 

percent, respectively.

The estimated errors in inventory sampling error 

being neglected and the foregoing expression for <rR being used are as follows: 18 percent for cesium-137, 

strontium-90, and rare earths ; 20 percent for cobalt-60 ; 

and 29 percent for ruthenium-106.

TABLE 4. Quantity of total identified radioactivity and volume of 

radioactive sediment in subreaches

Location of subreach Total identified 

radioactivity, in curies

Volume, in acre-ft

Begin End In subreach Cumula- In subreach Cumulative tive

CRM 0

2.80

5.90

8.95

10. 95

12.00

13.05

15.00

16.75

18.35

19. 85

20. 65

20. 90

CRM 2. 80

5.90

8. 95

10.95

12. 00

13. 05

15. 00

16. 75

18.35

19. 85

20. 65

20. 90

21.00

22

42

54

46

9

10

6.8

2. 2

4.7

. 1

2. 3

. 1

. 2

22

64

118

164

173

183

191

193

198

198

200

200

200

340

380

480

430

93

85

38

33

39

4.7

5. 9

1. 4

. 3

340

720

1,200

1,630

1,720

1,810

1,850

1,880

1,920

1,920

1,930

1,930

1,930

RETENTION FACTORS

The retention factor for a radionuclide is defined as 

the ratio, expressed in percent, of the quantity of the 

radionuclide in the sediment in July 1962 to that quantity released to the river during the period December 

1943 to July 1962.

The magnitude of the retention factor is independent 

of time if radioactive decay is taken into account.

I

/» *p

1= lidt,

(* T

0= lodt,

in which kr =retention factor, in percent,

/= inflow of radionuclide to study reach during time period T, in curies,

0=outflow of radionuclide from study reach 

during time period T, in curies,

R=quantity of radionuclide in bottom sediment of study reach at end of period T, 

in curies,

X=radioactive decay constant for radionuclide, in seconds -1,

T duration of time period, in seconds,

i=rate of inflow of radionuclide to study 

reach, in curies per second, a function of 

time,

o=rate of outflow of radionuclide from study 

reach, in curies per second, a function of 

time, and

t time, in seconds.

R may be expressed as a function of inflow and outflow if the effect of radioactive decay is considered.

odt

ie-KT-t) dt_ C T 

Jo

(*T (*

=e~*T idt-e~*T 

Jo Jo

Hence,

R 5^t^>(100)=^ (100) 

f, J. Jand is independent of time.
INVENTORY OF RADIONUCLIDES IN SEDIMENT, CLINCH RIVER, EASTERN TENNESSEE 113

Only annual records of inflow are available so that it 

is necessary to use numerical techniques to compute kr :

R le-*T* 

kr=^f^ (100),»=1,2J . . .,T years (1)

in which Rm =Re~*Ts= inventory of radionuclide at time

of radiochemical analysis, in curies, 

X= radioactive decay constant, in years, 

T^time between collection of cores and

radiochemical analysis, in years, and 

in= annual inflow of radionuclide to study 

reach during ^th year, in curies per year. 

Pickering (1969) had previously evaluated the dominator in equation 1 .

Using equation 1, the retention factors are computed 

to be 21 percent for cesium-137, 9 percent for cobalt-60, 

0.4 percent for ruthenium-106, and 0.2 percent for strontium-90. Retention of the rare earths may approach, 

and possibly may exceed, 25 percent (see Struxness and 

Morion, 1961). A good estimate of the retention factor 

for rare earths has not been obtained because mixtures 

of radioelements of undetermined composition are involved. The above estimate was derived from a conservative consideration of the cerium- 144 and other 

rare-earths contents of three samples.

DISTRIBUTION OF RADIONTTCLIDES 

LONGITUDINAL DISTRIBUTION

Patterns of longitudinal variation in mean concentration of principal radionuclides (fig. 9) are similar

40,000

50

22 20 18 16 14 12 10 8 6 4 2 0 

CLINCH RIVER MILE

FIGURE 9. Similarities in longitudinal distribution of radionuclides in 

bottom sediment are observed throughout study reach.

in most respects. Highest mean concentrations of radionuclides are in the two sections immediately downstream from the mouth of Whiteoak Creek (CKM 20.8 

and CKM 20.5). Lowest concentrations generally are in 

sediments of the next downstream sampling section at 

CRM 19.2. Secondary peaks in the distribution (fig. 9) 

occurred at CRM 17.5 and 14.0. Mean sectional concentrations for all but one radionuclide abruptly decreased 

between sections immediately upstream and downstream 

from the mouth of Poplar Creek (CRM 12.0).

Distribution of radioactivity in Clinch River bottom 

sediment is controlled primarily by sedimentation (Carrigan and others, 1967; Pickering, 1969). Radionuclides 

in the bottom sediment become intimately associated 

with suspended sediments passing through Whiteoak 

Dam. Patterns of radioactive deposits in the river result 

from the combined interaction of lateral diffusion, characteristics of the flow pattern, and decreasing intensity, 

downstream, of turbulent forces acting to suspend the 

radioactive sediment particles from Whiteoak Creek. 

Therefore, similarities in concentration distribution are 

to be expected.

Investigation of the movement of sediments has not 

been a part of the Clinch River Study. As a consequence, 

careful documentation of the effects of diffusion, flow 

distribution, and turbulence on sedimentation is not 

available. However, the influence of these three on the 

longitudinal distribution may be surmised from observation and general understanding of mechanics of fluid 

motion.

High concentrations of radioactivity in bottom sediments may be expected near the mouth of Whiteoak 

Creek. Dispersion of waters and suspended sediments 

from the creek into the river is restricted because of incomplete lateral diffusion (Morton, 1962b and 1963; 

Carrigan and others, 1967). Consequently, suspended 

sediments from Whiteoak Creek, which are rich in 

sorbed radioactivity, do not immediately became diluted 

with relatively uncontaminated river sediments.

Abrupt changes in the momentum of the water entering the river from the creek tend to induce deposition. 

Eddy zones along the right bank of the river immediately downstream from the creek mouth are created as 

the two streams meet. The eddies and the restricted dispersion of sediments produce immediate concentrated 

deposition of suspended sediments rich in sorbed radioactivity.

Suspended sediments from the creek diffuse outward 

into the river channel and mix with sediments carried 

in the river. This action prevents the formation of additional pockets of deposited sediments containing high 

concentrations of radioactivity.

Turbulence is of sufficient intensity in the upstream
114 TRANSPORT OF RADIONUCLIDES BY STREAMS

part of the study reach to keep sediments in suspension 

through reaches such as those near CRM 19.2.

The abrupt decrease in concentration of radionuclides 

in bottom sediment in the downstream direction at the 

mouth of Poplar Creek may be the result of dilution 

of contaminated river sediments by uncontaminated 

sediments from Poplar Creek.

About the time cores were collected for use in this 

inventory, the annual monitoring survey of radioactivity in Clinch River bottom sediment was 'being conducted by personnel of the Applied Health Physics 

Section, ORNL. In the monitoring surveys, attempts 

are made to collect samples of the upper part of the 

bottom sediment at equally spaced verticals in a sampling section. Sampling is clone with a hand-operated 

dredge. All sediment collected at a section is composited 

and radiochemically analyzed (Cottrell, 1959). The longitudial distribution of cesium-137, determined from 

the 1962 monitoring survey, is compared to the distribution determined from this inventory in figure 10.

VERTICAL DISTRIBUTION

Radionuclide concentrations are related to sediment 

thickness and location in the study reach. This relationship is shown in figure 11. The abscissa in the figure is 

the ratio of the thickness at a coring vertical to mean

1000

500

200

y loo

CL

13 

O

o

O 50

20

10

2 -

/"--Data from 1962 monitoring survey (Morton, 1965)

22 20 18 16 14 12 10 8 

CLINCH RIVER MILE

FIGURE 10. Longitudinal distributions of cesium-137 in bottom 

sediment, determined through different sampling techniques, are 

much alike.

thickness in the sampling section (shown in fig. 12); the 

ordinate is the ratio of the concentration of cesium-137 

in the core to its mean concentration in the sampling section (shown in fig. 9).

The increase in radionuclide concentration with relative thickness of sediment (fig. 12) may result from 

changes in the clay content of the sediment. Carrigan 

and others (1967) showed that the radionuclide concentrations increase as the clay content of the sediment increases. A linear regression analysis suggests that the 

clay-silt ratio increases as the relative thickness of the 

sediment increases (18 cores; correlation coefficient, 

0.46; regression coefficient, 0.042).

CONTRIBUTION TO INVENTORY FROM REACHES 

OUTSIDE OF STUDY REACH

Some of the radioactivity in bottom sediments within 

the study reach may have been contributed by fallout 

from weapons tests. Fallout is transported into the 

study reach primarily by flow from parts of the Clinch 

River basin upstream from the head of the study reach.

Contributions to the radioactivity in bottom sediments 

of the study reach from fallout appear to be negligible. 

Concentrations of radionuclides in bottom sediment at 

a sampling section 2.0 miles upstream from the study

4

2

1

0.8 

0.6

0.4 

0.2

0.1 

0.08 

0.06

0.04 

n 09

EXPLANATION 

O CRM 1.3 A CRN

A 4.3 

X 7.5 

V 10.0 n

-

)

/

<

/

/

O 

1

/

A

 I . 

Si

1 11.9 

12.1 

14.0 

17.5

X

V 

/

V

V

LJ

<

A

A

^

A

' 

'

I3 A

US

JS

L

p = 0.661 

SE = 0.348 log units

1 1

Xn/^ y 9^

^X

V X

o

A

0.04 0.1 0.2 0.4 1 

THICKNESS RATIO

FIGURE 11. Radionuclide concentration bears a nearly direct relationship to sediment thickness at specific sampling sections. 

Individual sectional relationships are a function of location in 

study reach, p is the coefficient of correlation for the logarithms 

of the concentration ratio and thickness ratio. Sa is the standard 

error of estimate.
INVENTORY OF RADIONUCLIDES IN SEDIMENT, CLINCH RIVER, EASTERN TENNESSEE 115

reach, CRM 22.8, 'are below limits of detection. Concentrations of cesium-137 and cobalt-60 in waters flowing 

past a water-sampling station at CKM 41.5 have been at 

or below limits of detection. No rare earths have been 

detected in water samples collected at this station. 

Kuthenium-106 and strontium-90 have been detected 

regularly in water samples (Churchill and others, 

1965); but these radionuclides constitute a minor fraction of the total inventory, and their retention factors 

are low.

Cores were collected in Poplar Creek and Emory 

Kiver to gage the extent of upstream movement of contaminated waters from the Clinch Kiver. Hydraulic 

conditions are such in the study reach of the Clinch 

River that upstream movement of water from the river 

can occur in any tributary.

Examination of gross gamma radioactivity scans of 

cores from Poplar Creek and from the section at mile 5.1 

on the Emory River indicates that the radionuclide content in bottom sediments at these sampling sites (fig. 2) 

is negligible.

Concentrations of radioactivity in some cores from 

mile 1.9 on the Emory River were above lower limits of 

detection.

Picketing, in a study of radioactivity in bottom sediments of sloughs adjacent to Clinch River (Carrigan 

and others, 1967),'noted that radiation levels in some 

areas approached levels measured at the surface of 

Clinch River bottom sediment.

Collectively, the evidence of radioactivity in bottom 

sediments in the lowermost reaches of tributaries to the 

Clinch River suggests that supplemental inventories 

might be undertaken.

DISTRIBUTION OP SEDIMENT

Ninety-five percent of the radioactive sediment in the 

Clinch River is downstream from CRM 15, and at least 

60 percent is downstream from CRM 9 (table 4).

A tendency for mean thickness of radioactive sediment to increase linearly from the head of the study 

reach to the mouth of the Emory River (CRM 21.0 to 

4.5) appears to exist (fig. 12). The general trend for 

increasing thickness may be explained by considering 

hydraulic conditions in the study reach. Accretions to 

flow in the study reach are almost negligible except 

inflow from the Emory River (U.S. Geological Survey, 

unpub. data, 1961). Flow area continuously increases 

in the downstream direction (Morton, 1962a). Without 

accretions to flow and with increasing flow area, 

velocity and intensity of turbulence of the stream decrease and consquently sediment transport capacity 

decreases in the downstream direction.

A decrease in mean thickness of radioactive sediment

3.0

2.5

z 2.0

1.5

1.0

0.5

I r 

General trend li

/\

-\t

22 20 18 16 14 12 10 8 6 4 20 

CLINCH RIVER MILE

FIGURE 12. Radioactive sediment thickness increases in the downstream direction as a result of increasing flow area.

of more than 50 percent occurs between sampling sections upstream at CRM 7.5, and downstream, at CRM 

4.3, from the mouth of the Emory River. This decrease 

in sediment thickness may be the result of a localized increase in turbulence due to inflow from the Emory River 

and (or) the diversion of Clinch River upstream into 

the Emory River (Elder and Dougherty, 1958). An 

increase in turbulence would tend to keep sediment 

particles in suspension.

At the mouth of Poplar Creek (CRM 12.0), the 

mean thickness of radioactive sediment sharply increases. Probably the decrease in radionuclide concentrations observed in this part of the streambed is due to 

dilution of radioactive sediment with uncontaminated 

sediments issuing from the creek.

The section at which sediment transport capacity 

rapidly decreases is clearly indicated to be at CRM 14.0 

in figure 13. From CRM 21.0 to 14.0, deposition is 

limited to zones of the channel near bank(s) of the 

river (Pickering, 1969). The sediment transport 

capacity is of much greater magnitude i" the central 

core of flow in this reach than near the banks. Though 

the magnitude of transport capacity remains greater in 

the central core of flow than elsewhere in the flow area 

throughout the study reach, its magnitude relative to 

that near the banks drops sharply in the vicinity of 

CRM 14.0.

The cross-sectional area of radioactive sediment is at 

a maximum at CRM 10.0 (fig. 13) because of the influence of islands and submerged ridges on the flow pattern 

in that vicinity (Carrigan and others, 1967, p. 27).

During the 191^-year period of waste disposal 

(December 1943 to July 1962), 64 percent of the streambed has become covered with radioactive sediment. Areal 

distribution of radioactive sediments, for selected 

thicknesses, is listed in table 5.
116 TRANSPORT OF RADIONUCLIDES BY STREAMS

20 18 16 14 12 10 8 

CLINCH RIVER MILE

FIGURE 13. Cross-sectional area of radioactive sediment increases 

most rapidly between CRM 14 and 10. Minor longitudinal variations occur upstream from this reach. An appreciable decrease 

in area begins at CRM 10.

TABLE 5. Areal distribution of radioactive 

sediments, for selected thicknesses

Radioactive sediment 

thickness, in feet

1. 0 

1. 5 

2.0 

2.6 

4.0

Proportion of radioactive surface 

area over which indicated thickness is equaled or exceeded

0.57 

.41 

.31 

. 24 

. 13

PHYSICAL PROPERTIES

Three physical properties of Clinch River bottom 

sediment that were measured are specific bulk weight, 

dry-to-wet weight ratio, and particle-size classification. 

Measurements of these characteristics have been 

restricted to radioactive zones in the sediment.

Mean specific bulk weight for all core composites 

is 100 pounds per cubic foot. Mean wet-to-dry weight 

ratio for all composites is 0.69. The dominant particlesize classification is silty clay based on the triangularplotting method of Shepard (1954). Results of extensive physicochemical analyses of radioactive sediment 

samples obtained in the 1962 coring program are 

reported by Pickering (1967).

FUTURE ESTIMATION OF RADIONUCLIDE LOADING

Continued decline of radionuclide releases to the 

Clinch River in recent years (see table 1) indicates that 

increasing radiation hazard in the future is unlikely. 

Cowser and Snyder (1965) found that, even if releases 

continue indefinitely at the highest experienced levels 

(in 1956 or 1959), bottom sediments will remain a minor 

source of radiation exposure. With continuing decline

of releases, further estimation of radionuclide loading 

in the sediments is not needed.

Waste disposal processes or quantities of wastes processed at ORNL could change such that releases to the 

river will increase. If releases of cesium-137, cobalt-60, 

and (or) rare earths should increase substantially above 

experienced levels for sustained periods, another safety 

analysis of radiation dosage from bottom sediment 

would be needed.

Safety analysis may be undertaken at two times: (1) 

after a period of increased loading to determine resultant radiation dosage and (2) prior to increased loading 

to estimate concentration and duration of releases which 

will assure safety.

For case 1, knowledge of retention factors would be 

an aid in estimating the magnitude of radiation dosage 

resulting from increased releases. The relationship of 

radiation dose to concentration of radionuclides in the 

release is

Z> = V2 (51.2) krCEf,

in which D is the dose rate, in rad per day, for beta or 

gamma radiation from an infinitely thick source uniformly spread over the bed of the study reach; kr is the 

retention factor in dimensionless units; G is the mean 

concentration of the radionuclide released for a known 

duration, with effects of radioactive decay taken into 

account, in microcuries per gram (10-6 curies per 

gram); E is the effective absorbed radiation of beta 

disintegration or maximum energy of gamma-ray emission, in million electron volts; and / is the fraction of 

disintegration of a particular energy, dimensionless. 

This equation for dose rate is derived from those proposed by Cowser and Snyder (1966; their eqs 14 and 17).

D is a nominal dose rate applicable to the study reach 

as a whole. As such, it is an indicator of relative hazard. 

If D approaches one-third of the critical dose rate, local 

dose rates may be approaching critical levels. Especially 

critical areas of the riverbed are along the right bank 

between CRM 20 and 21 and also in the vicinity of CRM 

4.3, 14.0, and 17.5.

For case 2, safety analysis would seek an estimate of 

the rate of buildup of radiation to the critical dose rate. 

Radiation dose at the surface of the sediment increases, 

in general, as the radioactive sediment becomes thicker. 

If the radionuclide releases are constant, this relationship between radiation dose and thickness is an exponential function. Cottrell (1959, fig. 17) indicated 

that the dose asymptotically approached a maximum 

in Clinch River bottom sediment at a thickness of about 

2.6 feet; Sayre and Hubbell (1965, p .47) found that 

this asymptote was somewhat less than 2.6 feet. This 

thickness (2.6 ft) was called the infinite thickness and 

its magnitude varied slightly with variations in physi-
INVENTORY OF RADIONUCLIDES IN SEDIMENT, CLINCH RIVER, EASTERN TENNESSEE 117

cochemical properties of sediment and with energy 

distribution of gamma-ray emissions.

Rate of buildup of radiation dose depends on the rate 

of accumulation of radioactiver deposits; rate of accumulation, in turn, depends on location in the study 

reach.

Data required to estimate radiation dose would be the 

rate of accumulation, or time to attain infinite thickness, 

and the interrelationship of radionuclide concentrations 

in releases and sediments throughout the study reach.

Information on sediment distribution is obtained 

from table 5 and from figure 12. Time required to attain 

an overburden of infinite thickness may be estimated 

by assuming that the rate of accumulation at a point 

on the channel bed is constant. The rate is assumed to be 

equal to the ratio of the radioactive thickness observed 

at the point in 1962 to the period of radionuclide releases 

from Whiteoak Creek 19.5 years. Using this estimate 

of the rate of accumulation, the time required to attain 

infinite thickness over various proportions of the riverbed is shown in figure 14.

From the relationship of concentration and thickness, 

(fig. 11) the interrelationship of concentrations in 

releases and in sediment may be derived.

CONCLUSIONS

The inventory of radionuclides in Clinch River 

bottom sediment provides strong insight to the fate of 

radioactive waste released to the Clinch River. The inventory is a direct and the principal measure of the 

residual between the 20-year input and output loads of 

the radionuclides to the study reach of the river.

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60

PROPORTION OF SURFACE AREA OF RADIOACTIVE

SEDIMENT OVER WHICH THE INDICATED

INITIAL THICKNESS IS EQUALED

OR EXCEEDED

FIGURE 14. An estimate of time required to accumulate 2.6 

feet of sediment over a given proportion of surface area 

is made by assuming that the observed net accumulation 

continues at the same rate.

In the study reach, at least 20 percent of the cesium137 and rare earths released to the river are retained in 

the bottom sediment. Retention of cobalt-60 releases is 9 

percent. Less than 1 percent each of the ruthenium-106 

and strontium-90 releases are retained in the bottom 

sediment. Most of the radioactive sediment is downstream from CRM 15. Because of downstream decreases 

in the turbulence of flow, the thickness, cross-sectional 

area, and volume per unit length of radioactive sediment are generally greater in the downstream parts of 

the reach than in the upstream parts. Of these three 

geometrical variables, only thickness varies in a regular manner, showing a linear increase in the downstream 

direction.

The total inventory of principal radionuclides in 

bottom sediment (cesium-137, cobalt-60, and rare 

earths) of the Tennessee River basin is undoubtedly 

greater than that measured in the Clinch River. Radionuclides have become associated with bottom sediment 

in sloughs and mouths of tributaries to the Clinch River 

and in the bed of the Tennessee River downstream from 

the mouth of the Clinch River (see Carrigan and others, 

1967).

Two methods of aiding future safety analyses are 

suggested: (1) estimation of dose rates for individual 

radionuclides incorporated in bottom sediment by consideration of mean concentration of radionuclides in 

releases and of the retention factor, and (2) consideration of (a) rate of sediment thickness buildup in various 

areas of the study reach, (£>) relation of concentration 

to sediment thickness, and (c) interelationship of 

concentrations in releases and in sediments.

Future use of the river for radioactive liquid-waste 

disposal is predicated on the safety of such practices. 

Present and past disposal practices have been safe 

(Cowser and Snyder, 1966) and, hence, have not limited 

usefulness of the river for such purposes. Continued 

decline in release of radionuclides would indicate that 

retention of radionuclides would not limit future usefulness. However, the possibility of an increase in 

radionuclide releases must be recognized. Assuming 

retention of 10 to 20 percent of some readionuclides in 

bottom sediment, a substantial increase in releases 

might be a factor leading to limited use of the stream 

for disposal of radioactive waste. Limitations resulting 

from an increase in radionuclide content of bottom 

sediment can be determined only through a safety 

analysis in which all avenues of radiation exposure are 

considered.

Water-sampling stations have value in obtaining continuous and current records of radionuclide concentrations at a site. However, measurements of small but 

significant losses or gains in radionuclide loads, occur-
118 TRANSPORT OF RADIONUCLIDES BY STREAMS

ring between stations of a network, are difficult and 

costly. Inventory of accumulated radioactivity in sediment is inherently more accurate than determining a 

small residual between large radionuclide loads measured at two water-sampling stations. Cost of such an 

inventory would be comparable to the annual cost of 

operating a two-station water-sampling network in the 

Clinch River study reach. The techniques of radioactive 

sediment inventory developed in this investigation can 

be used for long-term surveillance of release of radioactive material. And an inventory can be used in lieu 

of water-sampling networks.

REFERENCES

Browder, F. N., 1959, Radioactive waste management at Oak 

Ridge National Laboratory, in Hearings on industrial radioactive waste disposal before the Special Subcommittee on 

Radiation of the Joint Committee on Atomic Energy: U.S. 

86th Gong., 1st sess., v. 1, p. 461-514.

Carrigan, P. H., Jr., Pickering, R. J., Tamura, Tsuneo, and 

Forbes, Robert, 1967, Radioactivity in bottom sediments of 

Clinch and Tennessee Rivers, Part A, Investigations of 

radionuclides in upper portion of sediment: U.S. Atomic 

Energy Comm. ORNL-3721, Supp. 2A, 82 p.

Churchill, M. A., Cragwall, J. S., Jr., Andrew, R. W., and Jones, 

S. L., 1965, Concentrations, total stream loads, and mass 

transport of radionuclides in the Clinch and Tennessee 

Rivers: U.S. Atomic Energy Comm. ORNL-3721, Supp. 1, 

78 p.

Cottrell, W. D., 1959, Radioactivity in silt of the Clinch and 

Tennessee Rivers: U.S. Atomic Energy Comm. ORNL-2847, 

50 p.

Cowser, K. E., and Snyder, W. S., 1966, Safety analysis of radionuclide release to the Clinch River: U.S. Atomic Energy 

Comm. ORNL-3721, Supp. 3, 115 p.

Elder, R. A., and Doughtery, G. B., and 1958, Thermal density 

underflow diversion, Kingston Steam Plant: Am. Soc. Civil 

Engineers Hydraulics Div. Jour. Paper 1583, 20 p.

Garner, J. M., and Kochtitzky, O. W., 1956, Radioactive sediments in the Tennessee River System: Am. Soc,. Civil 

Engineers Sanitary Engineering Div. Jour. Paper 1051, 

20 p.

Morton, R. J., ed., 1961, Status report No. 1 on Clinch River 

Study: U.S. Atomic Energy Comm. ORNL-3119, 81 p.

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Atomic Energy Comm. ORNL-3370, 123 p.

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Atomic Energy Comm. ORNL-3409, 115 p.

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U.S.

U.S. 

Atomic Energy Comm. ORNL-3721, 149 p.

Pickering, R. J., 1965, Use of Swedish Foil Sampler for taking 

undisturbed cores of river bottom sediments, in Proceedings of Federal Inter-Agency Sedimentation Conference, 

1963: U.S. Dept. of Agriculture Misc. Publ. 970, p. 586-589.

 1969, Distribution of radionuclides in bottom sediment 

of the Clinch River, eastern Tennessee: U.S. Geol. Survey 

Prof. Paper 433-H. (In press.)

Raaen, H. P., and Cline, A. S., 1964, ORNL Master Analytical 

Manual, 1953-63: U.S. Atomic Energy Comm. TID-7015.

Sayre, W. W., and Hubbell, D. W., 1965, Transport and dispersion of labeled bed material, North Loop River, Nebraska: 

U.S. Geol. Survey Prof. Paper 433-C, 48 p.

Schonfeld, Ernest, Kibbey, A. H., and Davis, Wallace, Jr., 1965, 

Determination of nuclide concentrations In solutions containing low levels of radioactivity by least-squares resolution of the gamma-ray spectra: U.S. Atomic Energy Comm. 

ORNL-3744, 57 p.

Shepard, F. P., 1954, Nomenclature based on sand-silt-clay 

ratios: Jour. Sed. Petrology, v. 24, p. 151-158.

Struxness, E. G., and Morton, R. J., 1961, Radioactive waste 

disposal, in Health Physics progress report, period ending 

July 31, 1961: U.S. Atomic Energy Comm. ORNL-3189, 

80 p.

U.S. Public Health Service, 1960, Radiological health handbook [rev. ed.] : U.S. Dept. of Health, Education, and 

Welfare, Public Health Service, 468 p.

US. GOVERNMENT PRINTING OFFICE: 1969 O 331-517