LAKE MICHIGAN STUDIES
Special Report Number IM 6
RADIOCHEMICALv,IKVES!riGATIOHS
April 1963
o .8. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service
Division of Water Supply and Pollution Control
Great Lakes-Illinois River Basins Project
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TABLE OF CONSENTS
Subject Page
INTRODUCTION 1
Significance of Radiological Contamination 1
SAMPLE COLLECTION 3
LABORATORY PROCEDURE k
SOURCES OF RADIOACTIVE WASTE 5
Nuclear Reactors 5
Fallout from Nuclear Weapons Testing 6
Radioisotope Users 6
BESULTS OF ANALYSES 8
Lake Michigan Water Samples 8
Plankton Studies 9
SUMMARY AND CONCLUSIONS 11
REFERENCES 12
TABLES
FIGURES
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LIST OF TABLES
Table No. Title
1 Unsealed Isotope Use, Lake Michigan Watershed
2 Samples which had Alpha Radioactivity in
Excess of 3 niac/1
3 Percentage Distribution of Beta Radioactivity
in Water and Plankton Samples
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INDEX OF FIGURES
Figure
Number Title
1 Beta Activity - Total Solids
Cruise I, April 2k - May 7, 1962
2 Beta Activity - Total Solids
Cruise II, June 5 - June 18, 1962
3 Beta Activity - Total Solids
Cruise III, July 17 - July 30, 1962
k Beta Activity - Total Solids
Cruise IV, Aug. 29 - Sept. 9, 1962
5 Beta Activity - Total Solids
Cruise V, Oct. 10 - Oct. 22, 1962
6 Alpha and Beta Activity - Plankton
Cruise I, April 2^ - May 1, 1962
7 Alpha and Beta Activity - Plankton
Cruise II, June 5 - June 18, 1962
8 Alpha and Beta Activity - Plankton
Cruise III, July 17 - July 30, 1962
9 Alpha and Beta Activity - Plankton
Cruise IV, Aug. 29 - Sept, 9, 1962
10 Alpha and Beta Activity - Plankton
Cruise V, Octtt 10 - Oct. 22, 1962
11 Big Rock Point Reactor Site
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INTRODUCTION
An investigation of the existing radioactive contamination of
Lake Michigan was begun in April of 1962. Potential sources of
radioactive contamination have been identified, information has been
assembled on levels of radioactivity in tributaries to the Lake,
and samples from Lake Michigan have been collected and analyzed.
This report includes results of samples collected and analyzed
by the Great Lakes-Illinois River Basins Project from April 1962
until February 1963• Also included are selected data on radioisotope
users on the tributaries to Lake Michigan which were provided by the
states of Michigan and Wisconsin,
Significance of Radiological Contamination
Expanding production and use of atomic energy and continued
nuclear weapons testing are Increasing the amount of radiation in
the general environment. As a result, there is increasing public
health concern over the long term effects of radiation exposure and
in radioactive contamination of the environment.
Radioactive wastes discharged to the environment are not absorbed
in harmless fashion. Even though decay and dilution may occur,
radioactive wastes may be reconcentrated physically, chemically and
biologically so that the radioactive concentration can be increased
as it passes through the environment to the point of human contact.
Contamination of surface water by radioactive materials can
result in human exposure through the use of the water as a source
of municipal water supply and through the consumption of fish from
the water.
It is generally agreed that all unnecessary human exposure to
radiation is undesirable and should be prevented. However, if the
benefits of atomic energy are to be utilized, some radiation exposure
is inevitable, and various guides have been developed to minimize
the exposure. The National Committee on Radiation Protection (NCRP)
has recommended maximum permissible concentrations of radionuclides
for occupational exposure for many years, (l) In recent years the
Federal Radiation Council (FRC) has provided a Federal policy on
radiation exposure for the general public, (2) The Public Health
Service Drinking Water Standards of 19^2 have received widespread
use by various regulating agencies., (3) The radioactivity standards
for drinking water included in the above are generally accepted as
the criteria for evaluating the condition of untreated water for all
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uses, and are used as the frame of reference for this report. These
standards follow:
"Water supplies shall be approved without further consideration
of other sources of radioactivity intake of Radium-226" and Strontium-90
when Ra-226 does not exceed 3 micromicrocuries per liter and Sr-90
does not exceed 10 micromicrocuries per liter. In the known absence
of Sr-90 and alpha emitters the water supply is acceptable when the
gross Beta concentrations do not exceed 1000 micromicrocuries per
liter" (3).
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SAMPLE COLLECTION
A portion of each of the water samples collected for physical
and chemical analyses was used for radiological investigations.
A portion of each of the plankton samples collected for "biological
studies was used for radiological investigations.
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LABORATORY PROCEDURE
Radiological determinations were made at the Project laboratory.
The determinations vere made under the supervision of an experienced
radiochemist. Analytical procedures followed the methods described
in Standard Methods for the Examination of Water and Wastevater (k)
and the Radionuclide Analysis Laboratory Manual of the Public Health
Service (5).
Water samples were prepared on two inch diameter cupped aluminum
planchets. Plankton samples -••.•ere ashed and prepared on similar
stainless stsel plenche^s. Suspended solids were separated by membrane
filter, transferred to c, planchot oiid burned with ethyl alcohol.
Dissolved solids vere obtained by careful evaporation of the water
sample on a hot plate kept "hollow the boiling point, then complete
transfer of the solids to a pj.snchct. All planchets were dried and
fixed when necessary with lucite in acetone.
All of the samples were counted a-c least 59 days after the date
of collection« This delay in counting insures that any fallout in
the samples is at i.eaut 59 days olds In comparing results of analyses,
this rules out variations which could be caused by the effect of
fresh fallout products with rhort half lives.
Counting was done in a windowless internal proportional counter
(Nuclear Chicago D^-8) with a two inch lead shield and automatic sample
changer (NO Model C210 Special); combined with an NC Model 202 Sealer
and Hewlett Packard 560 A Digital Recorder0 All samples were counted
for thirty minutes (three 10 min» counts) and corrections were made
for geometry (G)^ backseatter (s), self-absorption (A), sample
volume (v), and background using the general equations:
Net cpm/GBAV 2»22 - gross radioactivity, p.nc/1 / C.E.
where: C.E. (j&uc/l) " 1.96 (cpms/tg / c^/t^/GBkV 2.22
where: C.E, = counting error at 95$ confidence level
cpm = counts per minute sample
S
cpm, = counts per minute background
net cpm - cpm^
D
t = counting time; sample
S
t, = counting tide; backgrotmd
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SOURCES OF RADIOACTIVE WASTE
Potential sources of radioactive wastes which could reasonably
be expected to find their way into Lake Michigan can be grouped into
these categories:
A. Nuclear Reactors
B. Fallout from Nuclear Weapons Testing
C. Radioisotope Users
These are in addition to the background radiation from naturally
occurring radionuclides in the earth's surface.
A discussion of each of these sources of radioactive wastes
follows :
A. Nuclear Reactors (Big Rock Point)
At the present time the Big Rock Point Reactor is the only
reactor located on Lake Michigan or its tributaries. The reactor
is located on the south shore of Little Traverse Bay, Lake Michigan,
five miles northeast of Charlevoix, Michigan (see Fig. ll). The
immediate vicinity of the reactor is heavily wooded and sparsely
populated and the shore line is rocky and barren. Big Rock is
a 1*8,000 KWE1, 157,000 KWT2 high power density, oxide fueled, direct
cycle boiling water reactor. The plant is owned and operated by
the Consumers Power Company of Michigan and was constructed by General
Electric Companyc The plant was completed in 1962 and became critical
in September of 1962. Full power operation is expected early in
Liquid wastes generated by the reactor are collected and routed
to a liquid radioactive waste system for appropriate treatment,
monitoring and release under batch control <, Cooling water and
service water can become radioactive only as a result of a leak in
the heat exchanger. This water can be released continuously but
the release is monitoredo 50,000 gpm of cooling water is available
for diluting radioactive wastes.
The plant discharge is limited by AEC and Michigan rules and
regulations (6) (7). Waste containing an unidentified mixture of
1 KWE ~ Kilowatt electrical
2 KWT s Kilowatt thermal
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radionuclides may be discharged if the^concentrations averaged over
365 consecutive days do not exceed 10~° nc/ml above that of plant
intake water from Lake Michigan. If the absence of Ra-226 and Ra-288
is demonstrated by appropriate analysis, the above limits may be raised
to 10~T ne/ml. All wastes are released to a discharge canal which
empties into Lake Michigan.
Accidental release of primary reactor water is the worst potential
source of radiological contamination which might be available. If such
liquid were drained to the waste collection tanks and accidentally
pumped to discharge at the maximum pumping rate available, the concen-
tration of the discharge canal would be on the order of 0.1 nc/ml.
Very large dilutions would occur within a short time after release and
combined decay and diffusion would limit the region of significant
contamination to a relatively small area. Any other surface or under-
ground leakage would be controlled by diking and by the low permeability
of the soil (8).
It can be expected that under normal operating conditions the
radioactivity added to Lake Michigan by the Big Rock Reactor will be
well within acceptable limits established by the Michigan Water
Resources Commission (7).
B. Fallout from Nuclear Weapons Testing
The contribution from fallout is probably the most significant
source of radioactive pollution in Lake Michigan. Besides the fallout
which occurs directly on the lake surface, additional and probably
greater amounts are collected by surface runoff to the tributaries to
Lake Michigan and from thence into the lake. In addition to the fall-
out, each of the tributaries may carry additional amounts of radio-
activity from the permitted discharge of the licensed radioisotope
users on the watershed.
C. Radioisotope Users
Production and use of radioisotopes has increased steadily since
they were first released for general use in 19^6. The radioisotopes
are licensed for use and regulated by the AEG for medical, educational
and industrial users. Much of the total activity shipped by the AEC
is used as sealed sources (9)« Sealed sources are designed so that
leakage of material is prevented. The bulk of remaining isotopes in
use have half lives of less than 30 days and are used chiefly in
medical diagnosis and therapy as well as in industrial development and
research. Some of this material can be expected to find its way into
the sewers; however, the amount would be small. Of 263 licenses in
Michigan, 15$ are located on the Lake Michigan watershed. Of 12^ licenses
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in Wisconsin 65% are located on the Lake Michigan watershed. Roughly
77$ of the Michigan and 23% of the Wisconsin licenses are for material
in sealed sources. A summary of unsealed sources in these states
appears in Table 1. A few more sources are undoubtedly located on
the relatively small area of the Lake Michigan watershed which is in
Illinois and Indiana but these sources were not pinpointed. It is not
possible to determine from this information how much of this activity
reaches the sewer system since much of it is either utilized or stored
and is either discharged to the sewer over a period of time or after
a period of significant decay.
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8
RESULTS OP ANALYSES
Lake .Michigan Water Samples
Results of gross radioactivity analyses of Lake Michigan water
samples are shown on Figures 1 through 5« Five cruises on Lake
Michigan from April, 1962 to October, 1962 are shown on these figures.
Gross beta radioactivity analyses in suspended solids and in
dissolved solids were made separately but the results were combined
in presenting these figures in order to simplify the presentation of
data. Gross alpha analyses were also made on these samples but so
few alpha results were above 3M-l-ic/liter that it was not meaningful to
plot the results. 99% of the total alpha results were below 3w*c/liter*
The few alpha results which were above SM^c/liter are shown in Table 2.
Each cruise is presented separately on these figures even though some
of the same stations were collected on different cruises. A comparison
of the data from these stations make it readily apparent that con-
siderable variation in the radioactivity concentrations occurred between
the dates of these cruises. Since complete coverage of the lake
requires several months to obtain, it is difficult to present the
results of these cruises as a whole in an effort to establish an overall
pattern of radioactivity in the lake. Similarly, since each cruise
was on a different area of the lake (except for Cruises 1 and 3)
there was insufficient sampling of the same stations to draw any con-
clusions regarding seasonal variations*
Figure 1 shows the results of gross beta activity analyses for
total solids on samples collected in the deep water in the southern
half of Lake Michigan during April and May 1962. To make interpretation
of the data as uncomplicated as possible all results of less than
10 micromicrocuriec per liter (10 nnc/l) are indicated by an open
square on the graph. All results between 10 i-it-ic/l and 20 nnc/1 are
indicated by a shaded square and numerical values are entered directly
in the square for all results above 20 M.p.c/1. The depth in meters at
which the sample was collected is indicated by the small number
directly beneath each square. It can be seen by a fairly rapid scan
of this figure that roughly half of the gross beta results fell below
10 MiiJ.c/1 and 31% of the results are in the range of 10 to 20 nuc/1.
Values in excess of 20 14-1 c/I (namely 20, 22, 23, 23, 24, 26, 2? and
39) occurred in 8 locations which are readily discernible. There
seems to be a random distribution of these high results both as to
location and in depth.
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Figure 2 shows the results of gross beta activity analyses on
samples collected in the northern half of Lake Michigan during June
and July 19&2. The data is presented in the same manner as described
for Figure 1. A rapid scan of this figure reveals approximately the
same percentage distribution of 10 M.M-C/! and 20 nn.c/1 results as in
Figure 1. Five values were in excess of 20 nnc/1.
Figure 3 shows the results of gross beta analyses on samples
collected in the same area as in Cruise 1 (Figure l) but collected
three months later.
A comparison of the results on these cruises (Figures 1 and 3)
proves very interesting. In Figure 3> 75$ of the results are less
than 10 w-ie/1, compared to k$% in Figure 1; all of the results in
Figure 3 are less than 20 wic/1 whereas Ik% of the results in Figure 1
are in excess of 20 nnc/lo These results will be referred to again
later in discussing the plankton analysis. Figures k and 5 show the
results of gross beta analyses on inshore samples collected on the
west side of the lower lake during August and September and on the
east side during October of 1962. A study of these data shows that
hO% of the samples near the west shore are above 10 M.M.C/I whereas
only 14$ of the samples on the east shore are above 10 ^nc/1. This
percentage on the west shore compares favorably with the percentage
distribution found on deepwater study (Figures 1 and 2). But the
results near the east shore and in Cruise 3 were in a class of their
own. Two high values of 23 ui-ic/1 and 112 HM.c/1 are found on Figure 5»
These results both occurred quite close to the mouth of two of the
major tributaries, the Muskegon River and the St. Joseph River and
could be expected at these points as a reflection of the levels of
radioactivity frequently encountered in streams. High values of tyj
and 53 found on the south shore off Tremont, Indiana, and 25 at the
Indiana-Illinois Line are not so readily explained however, nor is
the high result of 87 M-M-c/l found offshore from Highland Park, Illinois,
Plankton Studies
Figures 6 to 10 show the results of plankton studies in Lake
Michigan on the same cruises and same dates as described in Figures 1
to 5 f°r gross beta analyses of water samples. The plankton results
are presented in a slightly different manner. The radioactivity
levels in plankton are higher due to the concentrating effect in the
plankton. The plankton sample is obtained by a tow from near the
bottom of the lake to the top surface. This provides a rough composite
sample of all depths, and allows the alpha and beta results to be
presented graphically side by side since only two basic symbols are
needed.
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10
The alpha results are presented as an open circle for all results
less than 3 W-tc/g and by numerical designation inside the circle for
all results greater than 3 MUC/g. The beta results are presented
beside the alpha results by use of a square. An open square is used
for results less than 10 ni-ic/g, a quarter of the square is shaded for
re'sults less than 25 W-te/g (but more than 10 mac/g). Half of the
square is shaded for results more than 25 but less than 50. The range
50 to 75 is shown by three quarters of the square being shaded and from
75 to 100 by shading the entire square. All results greater than 100
are indicated by showing the numerical result above the shaded square.
A percentage distribution comparison of both the water and plankton
beta radioactivity results is made in Table 3« A study of this table
reveals that (as was pointed out earlier) from Cruise I to Cruise 3>
which were both deepwater cruises in the lower half of the lake but
three months apart, the percentage of the water samples above 10 ^(J.c/1
dropped from 50$ to 25$ and the percentage above 20 n^c/l dropped from
to zero. Now, looking at the plankton results it is found that
of the Cruise 3 plankton results are greater than 100 np-c/gram as
compared to only 4$ of the Cruise 1 plankton results. A comparison
of the cruises on this table also reveals that the highest radioactivity
results in the plankton samples (Cruise 3) were obtained simultaneously
with the lowest radioactivity levels found in the water samples.
These results indicate that the known ability of plankton to concentrate
radioactivity may be responsible for the above observation.
Comparing percent distribution of the plankton results of Cruise 2
and 3 with the other cruises suggests increased radiation levels per gram
of plankton in June and July« However these samples were collected in
different areas of the lake so nothing more than a general observation
can be made, which may or may not be supported by further study.
The geographic distribution of high beta radioactivity levels in
plankton seems to be entirely at random<> A study of the Figures 6
through 10, reveal the high results to be scattered without any pattern.
Cruise 3 which had high results from 100 to 700 on nearly all stations,
exhibited a uniform distribution of the highest and lowest values.
High alpha results in plankton also exhibit the same random
geographical distribution as the beta results, although the alpha
results are only a fraction of the beta results and are not as note-
worthy. It is interesting to see, however, that on Cruise 3 vhen the
plankton beta results were at their highest levels the alpha remained
the same or perhaps less than on the other cruises.
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SUMMARY AND CONCLUSIONS
The contribution from fallout is probably the most significant
source of radioactive pollution in Lake Michigan. In addition to
fallout -which occurs directly on the lake surface, fallout collected
by surface runoff is also contributed to the lake by the tributaries.
These tributaries also carry additional amounts of radioactivity from
the permitted discharge of licensed radioisotope users. Radioactive
wastes are also discharged to the lake from the recently completed
Big Rock Point nuclear power reactor, the only reactor on the lake or
its watershed at present. Under normal operating conditions the
radioactivity from this source is expected to be within acceptable
limits.
Water sample radioactivity analyses reveal only a few moderately
high results. The few alpha results found which were greater than
3 wac/1 were all located in the southern half of Lake Michigan and all
except one were more than ten miles from shore.
The few moderately high beta results found (20 to 112 i-il^c/l) were
evenly distributed between deepwater and inshore samples and randomly
distributed throughout the entire lake.
Studies of radioactivity in plankton samples also demonstrate
the same random distribution of high results throughout the entire
lake for both.a4.pha and beta results. The highest radiation levels
in plankton samples were obtained in the summer, simultaneously with
the lowest results found in water samples. The ability of plankton
to concentrate radioactivity may have been responsible for this
observation.
Results of the radioactivity in the effluent from the Chicago
sewage treatment plants were presented in the Report on the Illinois
River System, Part II, Table V-l4. The radioactivity found in the
effluent was no higher than some of the levels found in the lake,
therefore it does not appear that the return of this effluent to the
lake would have any appreciable effect on the radioactivity levels
in Lake Michigan.
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12
REFERENCES
1. Handbook 69. National Bureau of Standards, U.S. Government
Printing Office (June, 1959).
2. Background Material for the Development of Radiation Protection
Standards. Staff Report No» 1, Federal Radiation Council,
U.S. Government Printing Office (May 13, I960).
3» .Public, Health Servic_e DrinMne Water Standards. U.S. Department
of Health, Education and Welfare^ Public Health Service,
Washington 25., D.C= (1962)0
^•» Standard Methods for the. Examination of Water and Waste Water.
llth Edition, .American Public Health Association, American
Water Works Association, Water Pollution Control Federation
(I960).
5. Radionuclide Analysis of Environmental Samples. Technical Report
R-59-6, Robert A. Taft Sanitary Engineering Center, U.S. Public
Health Service, Cincinnati, Ohio (April 1962).
6. Atomic Energy Commission Rules and Regulations Title 10, Code
of Federal Regulations, Chapter 1, Parts 20 and 100.
7. Order of the Michigan Water Resources Commission in accordance
with Act 2^5, Public Acts of 1929 as amended by Act 117,
Public Acts of 19*4-9 (January 1961).
8. Hazards Summary Report, Big Rock Point Reactor, Consumers Power
Company (December 19^1).
9, Hearings Before the Special Subcommittee on Radiation of the
Joint Committee on Atomic Energy, Industrial Radioactive Waste
Disposal,, 1:1^0, 708; 111:2488, U.S. Government Printing Office
(1959)c
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TABLE 1
Unsealed Isotope Use
Lake Michigan Watershed
Type of Number of
User Users
1 State of Michigan
Indxistry 2
Medical 6
Educational 1
Amount of
Activity on Isotopes
Hand (Curies) Used
1.8 Atomic No. 3-83*, H-3, C-lU
Na-22, P-32, S-35, CJ1-36
1.0 Ca-lf.5, Cr-51, 00-58, Fe-59
1-131, Ir-192, Au-198
10.3 Po-210, V-233, Am-2la
Total (Michigan)
13-1
II State of Wisconsin
Industry 9
Medical 39
Educational 1
5=0 Atomic No. 3-83*
H-3, C-lfc, Na-22, Na-24
12.9 P"32, 8-351 Cl-36, K>42
Ca-if-5, Cr-51, Fe-55,
1.8 Fe-59, Co-58, Co-60
Ni-63, Br-82, Br-83
Rb-86, Sr-85, Sr-89,
Sr-90, Y-90, Ag-no
Ag-111, 1-125, 1-131, Ba-135
Au-198, Hg-203, EL-2CA
Total (Wisconsin)
19.T
81
Grand Total
58
32.8
*Broad licenses permitting use of any radioisotope between atomic
-numbers 3 and 83 within quantity limitations of the license
(usually for research purposes)..
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TABLE 2
Lake Michigan ¥ater Samples
April to October 1962
Samples which had Alpha Radioactivity
in Excess of 3 W-ic/1
Cruise
1
3
Station Number
Latitude
422300
422300
422300
422300
422300
443900
433600
Longitude
863300
872500
8T2500
870000
870000
861700
864700
Depth
(Meters)
50
5
75
5
125
5
110
a Activity
of Total Solids
(nnc/i)
3.2
6.9
3o3
4.8
3-2
3.7
3.5
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TABLE 3
Lake Michigan Radiological Studies
April-October 1962
Percentage Distribution of Beta Radioactivity
In Water and Plankton Samples
Percentage of Water Samples
Having Gross Beta Activity
Cruise
Ho.
1
2
3
4
5
1
2
3
4
5
Date of In Micromicrocuries/Liter
Cruise
April-May
June
July
Aug. -Sept.
Oct.
April-May
June
July
Aug. -Sept,
Oct.
< 10
49
56
75
60
86
> 10 < 20
37
38
25
35
11
> 20
14
6
0
5
3
Percentage of Plankton Samples
Having Gross Beta Activity
In Mieromierocuries/Gram
< 10
4
0
0
n
5
> 10 < 25
0
0
0
13
0
> 25 < 50
48
k
0
42
5
> 50 < 75
30
26
3
18
20
> 75 < 100
13
15
3
5
16
> 100
4
55
93
11
54
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