SWRHL-56r
PROTECTIVE ACTION TAKEN AT SCHOFIELD'S DAIRY
HIKO, NEVADA
FOLLOWING AN ACCIDENTAL RELEASE OF
RADIOACTIVITY FROM THE NEVADA TEST SITE
by
John S. Coogan and Wayne A. Bliss
Western Environmental Research Laboratory
ENVIRONMENTAL PROTECTION AGENCY
Pub I ished January I 972
This study performed under a Memorandum
Understanding (No. SF 54 373)
for the
U. S. ATOMIC ENERGY COMMISSION
of
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subcontractors, or their employees, makes any warranty, express or implied,
or assumes any legal liability or responsibility for the accuracy, or process
disclosed, or represents that its use would not infringe privately-owned
rights."
Available from the National Technical Information Service,
U. S. Department of Commerce
Springfield, VA 22151
Price: paper copy $3.00; microfiche $.95.
ObG
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SWRHL-56r
PROTECTIVE ACTION TAKEN AT SCHOFIELD'S DAIRY
HIKO, NEVADA
FOLLOWING AN ACCIDENTAL RELEASE OF
RADIOACTIVITY FROM THE NEVADA TEST SITE
by
John S. Coogan and Wayne A. Bliss
Western Environmental Research Laboratory*
ENVIRONMENTAL PROTECTION AGENCY
Published January 1972
This study performed under a Memorandum of
Understanding (No. SF 54 373)
for the
U. S. ATOMIC ENERGY COMMISSION
*Formerly Southwestern Radiological Health Laboratory, part of the U. S.
Department of Health, Education, and Welfare, Public Health Service,
Environmental Health Service, Environmental Control Administration,
Bureau of Radiological Health.
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INTRODUCTION
Protective Action Guide is a term often cited in health physics with consider-
ation to public exposure, but applied protective actions have been few. Any
protective action is unique with respect to the many possible influences. This
report defines a protective measure applied to decrease radioiodines in a
dairy's milk production and the factors judged in choosing the mode of action.
This action by the Western Environmental Research Laboratory (WERL) in concur-
rence with the Atomic Energy Commission was taken at levels below the Federal
Radiation Council guides and, although intended primarily as a feasibility study,
was a prudent measure for minimizing the potential thyroid dose.
On April 25, 1966, an underground nuclear test conducted at the Nevada Test
Site released radioactivity to the atmosphere. Weather conditions were such
that the effluent traveled from the Nevada Test Site in a northeasterly direc-
tion. Levels of radioactivity detected by portable instrumentation in the
immediate off-site area on the day of the test were low. The maximum exposure
rate in the off-site area was 8 mR/h, 42 miles from surface ground zero in an unpopu-
lated area. The highest exposure rate in a populated area was 1.5 mR/h at
Hiko, Nevada, 63 miles from surface ground zero in Pahranagat Valley.
Milk samples were collected in the Pahranagat Valley where family milk cows and
dairy operations were present. In addition to milk samples, other environ-
mental samples were collected simultaneously: natural vegetation, field forage,
green chop, dry hay- grain, water, air and soil. Environmental samples were
collected once daily with the exception of milk which was collected twice daily
after the morning and evening milkings. All samples were immediately taken
to the WERL in Las Vegas, Nevada, for laboratory analysis.
All samples were analyzed on systems using a 4- by 4-inch Nal(Tl) crystal coupled
to a 400-channel pulse neight analyzer. Results are reported in pCi/l for milk
or pCi/kg for vegetation.
Of the milk samples collected in the Pahranagat Valley, those from Schofield's
Dairy at Hiko showed the highest concentrations of I3II. The location with
the second highest concentration was about three-fourths of that observed from
Schofield's Dairy; however, this sample was from a family cow, the entire pro-
duction of which was utilized for sampling purposes. This report is concerned
only with circumstances involving Schofield's Dairy.
I
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RADIOLOGICAL SITUATION
Table I lists the initial radioiodine levels through the maximum observed
following contamination at Schofield's Dairy. These samples were composites
from cows of the main dairy herd.
Table I. Radioiodine Levels in Milk From Schofield's Dairy
Date and Time
Col lection
4-25
4-26
4-26
4-27
4-27
of
PM
AM
PM
AM
PM
I3lj
320
1,900
3,300
4,400
4,800
pCi/1
I32j
490
3,100
1,100
1,900
I33j
1,000
6,100
20,000
15,000
12,000
I35j
800
4,300
1 1 ,000
2,500
1 ,000
Field forage samples for the same location gave the following values (Table
2). The dairy herd was not eating this vegetation but it should serve as
a reference parameter in more areas than green chop (freshly cut growing
alfalfa and wheat).
Table 2. Radioiodine Levels in Field Forage From Schofield's Dairy
Date of Col lection
4-25
4-25
4-26
4-26
I3IT
120,000
460,000
140,000
85,000
I32T T
Tel
320,000
580,000
150,000
85,000
pCi/kg
I33T
310,000
580,000
300,000
160,000
I35j
220,000
390,000
48,000
27,000
Schofield's Dairy was feeding green chop and grain exclusively to its one
hundred and thirty-eight producing cows. The dairy was producing
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approximately 650 gallons of milk per day which was transported to a Las
'Vegas processing plant at two-day intervals.
Various means of determining whether radiation levels violate established
guides have been proposed. However, the most important consideration in
any situation of this sort is that radiation exposure should always be kept
at a mi nimum level.
Initial concentrations of radioiodine in milk from Schofield's Dairy were low.
Past experience indicated that the maximum concentrations in milk would be
reached at about five days after contamination. The levels of I on field
forage pointed toward relatively high I concentrations in the milk. Data
from past radioactive releases have shown that I in milk will reach a
maximum concentration of 0.015 to 0.15 times the I concentrations on vege-
tation. This indicated that the peak concentration of I in the mi Tk would
fall in the range of 6,900 to 69,000 pCi/l.
Ralph A. James, University of California, states a radiation field produced
by unfractionated fission products of 0.032 mR/h at H+24 hours is the field
131 *
corresponding to the FRC upper limit for range II of !•
An actual gamma exposure rate of O.I mR/h was measured at Hiko 24 hours after the
detonation. Based on this measurement and James' relationship, a concentration
131 **
of 8700 pCi/l of I in milk was estimated. Referring to "the FRC Report #5,
page II, "Deposition of " I can vary greatly within a relatively small geo-
graphical area. As a result, there can be large differences between I concen-
trations in milk produced on farms only a few miles apart." Then the text goes on
to state, "It is not possible to predict reliably the maximum concentrations of
of I in milk from deposition data." The prior statements are referenced
not to discredit the projected dose but to point out the uncertainty
"Calculation of Radioactive Iodine Concentrations in Milk and Human Thyroid
as a Result of Nuclear Explosions" Ralph A. James, University of California,
Lawrence Radiation Laboratory, Livermore, California, February 14, 1964,
Report #UCRL-77I6.
From this measurement, greater than three times FRC Range II, that is, more
than 8700 pCi/l of I3II in milk was projected.
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involved in projecting milk contamination from ground deposition data.
The Federal Radiation Council Report #5 states that from a single event
a total intake of 600 nanocuries of I would result in a dose of about
10 rads to a two-gram thyroid. It is estimated that a peak concentration in
milk of 60 to 70 nanocuries of I per liter could result in such thyroid
doses. The FRC does'not include approximately 20 to 25% of the infinite
thyroid dose which is obtained prior to the peak I concentration. It
is deduced then that a maximum concentration of 60 to 70 nanocuries
actually gives 12.5 to 13.3 Rad. Chapter 0524, Standards of Radiation
Protection, U.S. Atomic Energy Commission, gives 1.5 rem/year as a stand-
ard for thyroid dose to individuals of the population in an uncontrolled
area. It follows that 1.5 rem results from 6,800 to 8,400 pCi/l.
CONSIDERATIONS
These guides are based on FRC recommendations for exposure of the general
public for normal peacetime operations. Since Hiko is near the Nevada Test
Site, there was no assurance that another exposure would not result within a
year. Also, experience was needed in the application of preventive action and
its effects on the dairy herd, the contaminant levels, and the public. The
recommendation was made to the AEC to take protective action. The course of
action was chosen after considering the following:
A. The milk was being picked up from the producer dairy and
shipped to Las Vegas, Nevada (at two-day intervals). The
milk was being processed and delivered to the consumers
within thirty-six hours after receipt by the pasteuriza-
tion plant. Dilution at the pasteurization plant could
not have been greater than a factor of seven after pro-
portioning the milk in the plant's bulk tanks. The milk
was not normally proportioned in the tanks and to do so
would have created inconvenience and expense to the
processor.
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B. Disposing of the thirteen hundred gallons of milk would
have caused the processor to operate below his consumer
commitments since no other Grade A supply was available
for milk replacement. Therefore, disposal of the milk
was not a desirable protective action for this case.
C. Storage facilities for this large volume were non-existent
thereby eliminating the possibility of decreasing the
hazard through radioactive decay.
D. Diversion of the contaminated milk to milk products
seemed a likely procedure which would have allowed a
large reduction of the activity due to holding time.
This possibility was discarded, however, because the
producer would receive lower prices for milk which
must be diverted. Furthermore, there were no milk product
processing facilities in the nearby area.
E. The remaining possibility was replacing the dairy's
feed supply. This action was chosen as the most
feasible protective action to be taken, and it is one
of the actions recommended by the FRC for reduction
of human exposure from '^'l. Intake of the contaminant
would be cut to a minimum and contact with any persons
other than the producer would be unnecessary. The only
reduction in milk production would come from changing
the cow's feed. Reimbursement for this decrease would
be small. Replacement hay was available. This course
would also yield useful information as to the effects
of the protective action on the level of '3'l in milk.
PROTECTIVE ACTION
The following questions were then posed to the dairy operator:
A. Would he cooperate in feeding dry hay if the hay
was supplied without cost?
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B. What type and what amount of feed would be necessary?
C. How much, if any, hay was on hand at that time?
D. What time interval was necessary for the herd to be
switched to dry feed?
E. What hay suppliers could he recommend?
The manager of Schofield's Dairy was most cooperative and immediately agreed
to switch to dry hay and grain as soon as it was available. The nearest
supplier with suitable uncontaminated hay was contacted and delivery was
made on April 27. Dry feeding was initiated on the evening of April 27.
A small decrease of I in the milk was seen on April 28 and this decrease
was quite marked by April 29. Time was required for the clean feed to
purge the radioiodine already in the animals, but the following results
show that I levels dropped by a factor of four within two days after
the feed change.
Table 3. Radioiodine Levels in Milk Following Change to Dry Feed
Date and Time
Col lection
A- 9ft
A 9Q
of
AM
AM
PM
pCi/1
I3lj I32j I33j I35j
/ nnn — — f, 7nn — —
T. 7nn A 7nn
i Rnn i /inn
1 , 3UU — 1 , 4UU
i nnn — _ 7"^n —
Four cows were fed the regular diet of green chop and grain as a control to
assess the effect of the protective action. The I levels in their milk
decreased only about \0% per day. The milk from these cows was not used
for human consumption. The following graph depicts the trends seen in
both groups. It is estimated that this action reduced the I thyroid
dose by 71%. Schofield's Dairy continued to feed dry hay for 16 days,
time for 2-3 effective half-lives of I to pass and acceptable levels of
I to be reached. The cows were then returned to their normal diet.
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PIN STRIPE EVENT APRIL 25, 1966
Schofield Dairy, Hiko, Nevada
I31I in Milk of Cows eating
contaminated green chop (DecaycxT—O.7)
131I in Milk of Cows after changing
to uncontaminated hay (Decay=xT—5.O)
4 cows remaining on
contaminated feed
uncontaminated
feed placed
before main herd
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CONCLUSION
The initial considerations of peak '^'l concentrations in vegetation at
Schofield's Dairy pointed to maximum levels in milk about ten times higher
than those reached. Using the James' model relationship, the estimated
milk levels were within about a factor of two of the measured peak level.
Two features become paramount in handling any situation where protective
action may be needed. The first is to sample all possible sources which
may delineate and quantitate the contamination. The second, a quick assess-
ment of the total radiological situation is necessary before employing pro-
tective action.
This paper has assessed a specific case which may or may not be a precedent
for planning similar protective actions. Any incident would have to be
judged on the set of circumstances controlling its situation. The para-
meters set forth here are those used to judge this situation and to deter-
mine the course of action taken. Under different circumstances, other
equally important issues may need to be considered by the group responsible
for taking the necessary precautions.
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DISTRIBUTION
15 Western Environmental Research Laboratory, Las Vegas, Nevada
16 Robert E. Miller, Manager, NVOO/AEC, Las Vegas, Nevada
17 Robert H. Thalgott, NVOO/AEC, Las Vegas, Nevada
18 Henry G. Vermillion, NVOO/AEC, Las Vegas, Nevada
19 Robert R. Loux, NVOO/AEC, Las Vegas, Nevada
20 Donald W. Hendricks, NVOO/AEC, Las Vegas, Nevada
21 Mail & Records, NVOO/AEC, Las Vegas, Nevada
22 Chief, NOB/DASA, NVOO/AEC, Las Vegas, Nevada
23 Ernest D. Campbell, NVOO/AEC, Las Vegas, Nevada
24 Technical Library, NVOO/AEC, Las Vegas, Nevada
25 Phi I ip W. AI I en, ARL/NOAA, NVOO/AEC, Las Vegas, Nevada
26 Martin B. Biles, DOS, USAEC, Washington, D. C.
27 Ralph S. Decker, Safety Div., SNSO, USAEC, Washington, D.C.
28 John P. Jewett, SNSO-N, Jackass Flats, Nevada
29 Assistant General Manager, DMA, USAEC, Washington, D.C.
30 John A. Harris, PI, USAEC, Washington, D.C.
31 John S. Kelly, DPNE, USAEC, Washington, D.C.
32 Charles Bild, Sandia Laboratories, Albuquerque, New Mexico
33 George E. Tucker, Sandia Laboratories, Albuquerque, New Mexico
34 Chief, Weapons Test Div., DNA, Washington, D. C.
35 Bernard W. Shore, LLL, Livermore, California
36 James E. Carothers, LLL, Livermore, California
37 Roger E. Batzel, LLL, Livermore, California
38 WilliamC. King, LLL, Mercury, Nevada
39 Howard A. Tewes, LLL, Livermore, California
40 Lawrence S. Germain, LLL, Livermore, California
41 L. Crooks, LLL, Mercury, Nevada
42 Harry J. Otway, LASL, Los Alamos, New Mexico
43 William E. Ogle, LASL, Los Alamos, New Mexico
44 Charles I. Browne, LASL, Los Alamos, New Mexico
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Distri but ion(continued)
45 Harry S. Jordan, LASL, Los Alamos, New Mexico
46 Gilbert J. Ferber, ARL/NOAA, Silver Spring, Maryland
47 Stanley M. Greenfield, Assistant Administrator for Research & Monitoring,
EPA, Washington, D. C.
48 Acting Deputy Assistant Administrator for Radiation Programs, EPA,
RockviIle, Maryland
49 Paul C. Tompkins, Acting Director, Division of Criteria & Standards,
Office of Radiation Programs, EPA, Rockvilie, Maryland
50 Ernest D. Harward, Acting Director, Division of Technology Assessment,
Office of Radiation Programs, EPA, Rockvi Me, Maryland
51 - 52 Charles L. Weaver, Acting Director, Division of Surveillance & Inspection,
Office of Radiation Programs, EPA, Rockvi Me, Maryland
53 Gordon Everett, Director, Office of Technical Analysis, EPA, Washington, D.C.
54 Bernd Kahn, Chief, Radiochem. & Nuclear Engineering, NERC, EPA, Cincinnati, 0.
55 Richard S. Davidson, Battelle Memorial Institute, Columbus, Ohio
56 R. Glen Fuller, Battelle Memorial Institute, Las Vegas, Nevada
57 Arden E. Bicker, REECo, Mercury, Nevada
58 Frank E. Abbott, USAEC, Golden, Colorado
59 John M. Ward, President, Desert Research Institute, University of Nevada, Reno
60 - 61 DTIE, USAEC, Oak Ridge, Tennessee
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