ORP-TAD-78-1
A SURVEY OF PACKAGING FOR SOLIDIFIES
LOW-LEVEL RADIOACTIVE WASTE
BATTELLE
Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201
May, 1978
This report was prepared as an account of work sponsored by the
Environmental Protection Agency of the United States Government
under Contract No. 68-01-3924,
Project Officer
William F, Holcomb
Radiation Source Analysis Branch
Technology Assessment Division
Office of Radiation Programs
U.S. Environmental Protection Agency
Washington, D.C." 20460
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ABSTRACT
There are no federal regulations controlling the packaging of
low-level radioactive wastes for disposal by shallow land burial. As a
result the regulations of the U.S. DOT for the packaging of radioactive
materials for shipping have been a major influence in packaging for this
method of disposal. Ocean disposal of radioactive materials has not been
practiced in the United States for a decade. The packaging of low-level
radioactive wastes for ocean disposal"by the European community has been
controlled by guidelines of the Nuclear Energy Authority of the OECD, For
both methods of disposal, the 55-gallon steel drum has been the most
commonly used container. The use of nonmetal packaging has been more
common for contaminated trash and other low-level wastes at DOE shallow
land burial sites. The life of the disposal container is affected by
the structural stresses imposed by the handling and disposal operations,
and by deterioration from corrosion in the disposal environment. Whereas
data show that steel drums may be penetrated by corrosion in some soils
or sea water In 2 to 4 years, inspection of drums after disposal has
shown a range of lifetimes from a few years to a decade or more. The
coatings presently used on drums are ineffective because of defects
which occur during handling and disposal operations. The radiation
exposure to concrete, bitumen, or polymeric solidification media by the
incorporation of typical low-level radioactive wastes is not expected
to cause significant structural damage to the waste form. Longer con-
tainer life may be achieved by improving the structural strength of the
containers to withstand the stresses applied by handling and disposal
operations and by increasing the compatibility of the container with
the interior and exterior environments. A thorough systems study of
the roles of the disposal, environment, the waste form, and the waste
container in restricting the transport of radionuclides from the disposal
area is needed to show the cost-effective benefits to be gained from
improved container integrity.
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TABLE OF CONTENTS
ABSTRACT
1.0 INTRODUCTION ...... 1
2.0 -STATE OF THE ART OF PACKAGING FOR DISPOSAL OF SOLID LOW-LEVEL
RADIOACTIVE WASTE BY SHALLOW LAND BURIAL OR DEEP SEA BURIAL. .... 2
2.1 Background .,,,.,» 2
2.2 Packaging for Low-Level Radioactive Waste for Shallow
Land Burial. 4
2,3 Packaging for Low-Level Radioactive Waste for Ocean
Disposal . . . 8
3.0 EFFECTS OF THE DISPOSAL ENVIRONMENT ON THE LIFE OF WASTE
PACKAGING 10
3.1 Deterioration of Containers by Corrosion and
Decomposition, , 10
Metal Corrosion by Soils 10
Corrosion by Seawater ..... 12
Corrosion by Contents of the Container. ......... 14
Discussion of Corrosion of Metal Containers ........ 14
Decomposition of Wood Containers in Soil. 15
3,2 Effects of Radiation Damage to Waste Packaging 17
Effect of Composition ....... ... 17
Radiation Source and Estimated Dose ........... 18
Radiation Effects 19
3.3 Structural Effects of Waste Containers . ..... 22
Structural Characteristics of Waste Containers 22
Observed Structural Performance of Waste Packaging. ... 25
4.0 TYPICAL LOW-LEVEL WASTE PACKAGING 26
5.0 RECOMMENDATIONS. . 29
6.0 REFERENCES ... ....,' 35
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TABLE OF CONTENTS (Continued)
Page
LIST OF FIGURES
Figure 1, Approximate P«se Rate in Waste7Containers With
4.7-,Ci:/g Co6 ; 3.3 Ci/g Cs ; 2.00 Ci/g
Cs1J^ 21
Figure 2. Approximate Dose Absorbed in Waste Composites . 21
LIST OF TABLES
Table 1. Description of Four Typical Waste Packages 26
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1.0 IMTRQDUCTION
The disposal of radioactive wastes has become a key issue in the
development of the nuclear power industry. Since the early years of
nuclear technology many of the wastes have been disposed of by shallow
land burial and ocean disposal. As the technology has advanced there
has been a growing awareness of the need to improve the management of
nuclear wastes to protect the present and future environment of man.
To this end, many facets of nuclear waste management are being studied
to develop the information base for the formulation of criteria and to
define specific needs for research and development.
This study was conducted for the United States Environmental
Protection Agency by Battelle's Columbus Laboratories to assist in
defining the role of packaging in the disposal of low-level radioactive
wastes by shallow land burial or ocean disposal. In this study a
literature search was conducted from which a summary of the state of the
art of packaging for low-level waste disposal was prepared. This report
also contains a discussion of effects of the disposal environment upon
the life and integrity of the packaging. From this information recommenda-
tions are made for further improvements in the packaging as a containment
for the radioactive wastes.
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2.0. STATE OF THE ART OF PACKAGING FOR DISPOSAL
OF SOLID LOW-LEVEL RADIOACTIVE WASTE BY
SHALLOW LAND BURIAL OR DEEP SEA BURIAL
2.1 Background.
To place this brief review in perspective it is desirable to
define the title to minimize the ambiguity that may exist concerning
its terms. There has been a gradual evolution of the state of the art
of packaging since the need for disposal of radioactive waste began in
the 1940's. To be of most benefit the art in practice during the past
five years is the objective of this discussion. It is most common to
describe the packaging for radioactive materials where the term packaging
refers to one or more wrappers or containers and their components such
as structural members, shielding, and seals, A package refers to the
packaging and its contents, in this case the waste. However, when
considering the retention of wastes after disposal the performance of
the packaging can also be influenced by the contents as well as the
disposal environment thus in the broader view it is prudent to include
both packaging and typical contents.
There is no generally accepted definition of "low-level
radioactive waste" as there is for "high-level waste". Often "low-
level waste" is used synonymously with "low specific activity" or
"low radiation level". This is confusing as all radioactive waste
except "high-level waste" may be properly identified as "low-level waste".
Since 1970 wastes contaminated by transuranic elements at levels in excess
of 10 nanocuries per gram (referred to as TRU wastes) have not been
accepted for disposal at AEG (now DOE) shallow 'land burial sites. Rather,
they are placed "in 20-year retrievable storage for ultimate disposal in.
a Federally operated repository which is to be constructed at some future
time. Five of the six commercial low-level radioactive waste burial sites
have followed this example and do not accept TRU waste for burial. Thus
where the disposal by land burial is concerned it is logical to assume that
TRU wastes are not included. Also, by nature of their large volume and low
specific activity the tailings from uranium and phosphate ore operations are
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not considered for disposal in shallow land burial sites. Therefore, for
this application "Low-Level Wastes" (LLW) are those wastes other than those
specifically categorized as high-level and TRU wastes or mine and mill
tailings. As implied by the definition, LLW varies in its source, physical,
chemical, and radiological properties and ranges from slightly contaminated
paper wipes and coveralls to highly activated structural components of
nuclear power reactors. The wide range of properties of LLW could be
illustrated as below:
• Physical form; trash, laboratory animals, ion exchange
resins, evaporator sludges, filters,
sorbed and solidified liquids, sealed
sources, reactor parts, parts of build-
ings and structures
* Chemical form; soluble salts, insoluble materials,
cleaning solutions, acidic solutions,
basic solutions, coraplexing agents,
and organic compounds
» Radioactivityt levels range from those with barely
detectable or no detectable activity,
to those with activity levels high
enough to require shielding for trans™
port and handling
* Sources of waste; hospitals, research institutions,
universities, commercial manufacturers,
Federal facilities and nuclear power
production facilities.
The LLW waste form will be a dry solid or excess liquid will be chemically
or physically immobilized in a suitable matrix such as concrete, or an
adsorbent such as vermiculite.
The disposal of radioactive wastes during the war years of
(1 2)
1941-1945 was conducted by burial at the site at which they were produced. '
Fortunately the quantities were small, the transuranics were carefully
conserved for their own value, and the separated fission products were
not a serious problem. In the post-war period as nuclear research and
development expanded, the increased quantities of radioactive waste and
contaminated equipment forced attention to the disposal problem. In the
United States new burial grounds were selected with greater care at ABC
sites and many old sites were no longer used. Some wastes produced by
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commerce and industry were accepted for burial at AEG sites, but the
majority was buried at sea by private companies. From 1962 through 1971
six commercially operated burial grounds began operation. In the late
1960's, although not prohibited, the practice of sea disposal was phased
3
out. Through 1976 it is reported that over 4.2 x 105 m of low level
waste initially containing 3.9 x 10 curies of byproduct material have
been buried at commercial sites and it is estimated that 1.5 x 10 m
has been buried at DOE sites. Approximately 95,000 Ci of waste
were buried at three dumping sites off of our Atlantic and Pacific coast
lines.
In Europe, the scarcity of suitable land for burial sites has
led to the practice of sea disposal. Between 1951 and 1966 the United
Kingdom disposed of 40,000 Ci of waste in the Atlantic Ocean. From 1967
through 1976 approximately 29,400 Ci of wastes were dumped by various
European countries under the control of the Nuclear Energy Agency of the
Organization for Economic Cooperation and Development.
2.2 Packaging for Low-Level Radioactive
Waste for Shallow Land Burial
There are presently no Federal rules or regulations which specify
the packaging to be used for shallow land burial of radioactive waste. To
the present time there is no credit given to the packaging for the
retention of the radioactive products after the package is buried. The
packaging is intended to protect the personnel handling the waste and
the general public from unnecessary radiation exposure by direct radiation
or by transferable contamination from the time the waste is packaged
until it is buried. To meet this objective the packaging has been
controlled by the rules of the waste-generating facility, the regulations
for transportation, and the rules of the operators of the burial ground.
It is possible that one organization can perform all of these functions
and be the only control over the packaging. Usually this is not the case.
The waste-generating site may have a government, an industrial, or a
commercial operator which may package the waste or may engage another
company to perform the service. The transportation of the radioactive
material may be controlled by Federal, state or local rules and regulations,
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The burial grounds may be operated under contract to DOE or by commercial
operators. Of these, the greatest influence on the packaging is exercised
by the rules and regulations of the U.S. Department of Transportation for
transportation of hazardous materials, 49 CFR 170-199.' ' The licensing
of packages for shipping radioactive materials is controlled by the
regulations of the U.S. Nuclear Regulatory Commission in 10 CFR 71.'°'
The regulations for the packaging for the transport of radio-
active materials are dependent upon the type and quantity of materials
to be shipped. Some low-level wastes may be classified as low specific
activity (LSA) material as defined in 49 CFR 173.389. These wastes only
require strong, tight, industrial shipping packaging when shipped by sole
use vehicle. When shipped by common carrier LSA materials must be shipped
in DOT-approved packaging. In either case the radiation-dose limits of
49 CFR 173.393 apply as they do for all other types of packaging.
Other categories of radioactive materials are Type A, Type B
and "large quantity" as defined in 49 CFR 173.345 and 173.389. The
allowable quantity in each category is related to the nuclides to be
transported. For this purpose most nuclides have been classified into
seven transport groups according to their relative hazard, Transport
Group I being most hazardous. For example, for Type A quantities most
of the classified nuclides are limited to a total not to exceed 20
curies. However, many other nuclides, including the common waste products
Co-60 and Cs-137 are not to exceed a total of 3 curies. Most nuclides
of heavy metals and those with very long half-life are limited to a
small fraction of a curie. Type B quantities are nominally a factor of
10 or more greater than Type A, and most waste products would be permitted
in quantities as great as 200 curies. "Large quantities" are those that
exceed Type B quantities.
The packaging for the shipment of Type A quantities must meet
the DOT specification 7A for Type A general packaging, 49 CFR 178.350.
Prior to 1976 a large variety of DOT approved Type A containers were listed
in 49 CFR 173,395 including metal and fiber drums, and fiber and wooden
boxes in a range of sizes. Specifications for each are given in 49 CFR 178,
The specifications list size, configuration, type and thickness of materials
of construction, type of closures, pre-use testing, limitation on contents,
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and external markings. Other Type A packaging available includes steel and
concrete bins and shielded containers. Beginning in 1976 the paragraph
173.395 was modified to delete approval for specific containers and now
gives approval only for containers meeting the general 7A specification.
However, this paragraph had a large affect on the state of the art of con-
tainers, particularly in the use of DOT Specification 17H steel drums.
Type B quantities and large quantity shipments must use a DOT
specification 6M container or specially approved Type B containers.
Approval of these containers and a Certificate of Compliance may he
received from the NRG by compliance with the regulations in 10 CFR 71.
The most common container used for packaging low-level wastes
for disposal by shallow land burial is the steel drum. The 55-gallon
drum is most common but 30-gallon and smaller are also used. These are
usually painted on all surfaces for corrosion resistance and for some
applications plastic bags or rigid liners are used for additional
containment. Steel drums are relatively inexpensive, easy to load and
handle, and have been acceptable for disposal at all burial grounds,
DOT-approved steel drums serve as Type A packaging for the shipment of
Type A quantities and LSA waste. The wastes can be loaded into the drums
at the waste collection area, the drums shipped by common carrier to the
disposal site, and the drummed waste can be placed directly into the burial
trench. Where radiation levels must be reduced to meet DOT external dose
rate requirements a concrete liner or other suitable shielding material
may be placed in the drum within the weight limitation of the drum. Wet
wastes which require solidification prior to disposal are often mixed
with a solidifying agent, such as cement or urea formaldehyde resin, and
cast directly into a drum. Often the drum is used as a receptacle into
which loose trash is compacted prior to disposal. Dewatered ion exchange
resins and sludges are loaded directly into drums at some sites but these
have not been acceptable for disposal at all burial grounds because of
(9)
their moisture content. For some highly mobile wastes, such as tritium,
it is common practice to utilize a sealed inner metal or plastic liner,
or a polymeric sealed concrete matrix within the outer metal drum as an
additional barrier for the containment of the waste.
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Steel drums are also utilized as packaging for Type B or larger
and high-radiation-level Type A quantities of radioactive wastes where the
drum does not qualify as a shipping package. In this case the drums are
shipped in an overpaek which serves as the approved shipping container.
For example unshielded Type B overpacks are available which can hold 42
55-gallon drums for transport by truck, rail, or cargo vessel. Shielded
Type B overpacks are typically smaller in size and capacity so that the
total weight does not exceed the limits for truck shipments. When
delivered to the burial ground the drums are withdrawn from the Type B
container and placed into the burial trench; the shipping container is
returned for reuse.
Larger metal containers have found increased use where large
volumes of waste products must be disposed of on a routine basis. It has
been found more economical to use containers with ten or more times greater
capacity than the 55-gallon drum. Waste packages of this size must be
shipped in an overpack so the containers are designed as disposable liners
for specific DOT-approved shipping containers. These large containers are
commonly used for shipping used ion exchange -resins from commercial power
<>
reactors. Low activity resins may be shipped in 160 to 180 ft liners
in an overpack with shielding equivalent to 2-in. of lead. Resins with
a higher specific activity, may qualify as Type B or large quantities
and be shipped in 70-ft3 liners which require an overpack with shield-
ing equivalent to 4-in. of lead. These large metal containers are made
in a cylindrical configuration of carbon steel with welded seams, The
containers have a relatively thin (nominally 1/4-in) wall and are equipped
with lifting lugs and fittings for filling, venting, and removing water.
Nonmetal packaging is being utilized for trash with low levels
(2)
of contamination. One DOE laboratory disposes of the majority of its
loose trash by sealing it in plastic bags which are then placed in card-
board boxes or small fiber drums. ' Another DOE laboratory compacts
3
solid low level waste into 14 ft bales contained in plastic lined fiber
(12)
board boxes. At both sites these waste packages are buried in an onsite
shallow land burial area. Another DOE laboratory packages low-level waste
(13)
for disposal in DOT 7A plywood boxes with P?C or fiberboard liners.
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These waste packages are shipped off-site for disposal at another DOE
shallow land burial site. Cardboard boxes are not acceptable packaging
at most commercial burial grounds and non-metal packaging for commercial
sites is limited to less frequently used DOT approved non-metal packaging,
2.3 Packagingfor Low LevelRadioactive
Waste for Ocean Dj.sj^osal_
The current state of the art of packaging of radioactive waste
for ocean disposal is established by practices of the European community.
The Nuclear Energy Agency (NEA) of the Organization for Economic Cooperation
and Development has published guidelines for packaging of wastes for ocean
disposal which cover the design, manufacture, assembly, handling and trans-
(14)
port of the packages, The packaging is to be designed to assure adequate
containment of the waste during handling and transport until the end of the
disposal operations. The package should have adequate shielding to allow
safe handling during all phases of the operation. The package and any
inner containers should have a specific gravity of not less than 1.2 to
assure sinking to the sea bed. Also, the package should have adequate
strength to maintain its structure, or to have a pressure equalization
system to assure that the packaging will retain its contents for an indefinite
time after reaching the sea bed.
The guidelines describe two general type of packages, a monolithic
design and a multistage design. In the monolithic design the waste is
incorporated into a solid mass with no significant voids. The monolithic
block provides a rigid inner structure which strengthens and supports the
packaging during handling, transport, and submersion. An example of this
is waste mixed with concrete or bitumen and cast into a steel drum without
any significant internal voids. The solidified block acts as an ineompressable
support for the drum wall and heads. The multistage design has aiulticomponent
assembly and may contain significant internal voids which require a pressure
equalization system to prevent structural failure of the packaging during
submersion. An example of this is compacted, contaminated trash bundles
placed in a concrete liner in a steel drum; a penetration with a check
valve would allow pressure equalization as the package is submerged. The
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packaging is the steel drum; the concrete liner serves as shielding but
does not necessarily provide adequate structural support for the drum
during submersion. A monolithic package needing additional shielding
can be placed in a concrete overpaek, or a concrete-lined steel overpack
converting it into a multistage design.
The NEA guidelines have recommendations for construction as well
as radiation levels, surface contamination limits, criticality control,
weight limitations and markings.
In the United States, EPA has authority over ocean disposal
including low-level radioactive wastes, and the regulations address
containerization of wastes. However, since ocean disposal of radio-
active wastes has not been practiced in this country for a decade, the
regulations have not influenced the current state of the art.
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3.Q EFFECTS OF THE DISPOSAL ENVIRONMENT
ON THE.LIFE Of WASTE PACKAGING
3_..l Deterioration of Containers
bsi Corrosion and Decomposition
Penetration of metal containers "by corrosion is one of the failure
modes that can result in breaching of the container. Failures from corrosion
evolve slowly (months to years) and total area' penetrated may also grow
slowly, i.e., the lateral growth of a pit. Both ocean disposal and soil burial
environments can be corrosive to the external surface of steel containers;
moist contents of the containers can lead to corrosion to internal surfaces,
particularly if acid constituents are present. Containers of x20,000
However, severe pitting has been observed in 100,000 ohm-cni soil, so that
resistivity alone cannot accurately predict corrosivity, but can serve as a
general guide.
Because of the complex nature of soils, this corrosivity can vary
widely. At this time, it is not yet possible to predict corrosivity based
on soil analyses alone. In fact, similar soils from different locations in
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11
the United States may have vastly different corrosive tendencies. Concentra-
tions of trace chemicals and organic matter can vary widely and, since these
are not considered in normal analyses, can account for the wide ranges of
corrosivity.
In the projected applications, conventional 55-gallon steel drums
are being considered. These normally are coated on the exterior with a thin
lacquer finish. If undamaged, this type of coating affords, protection in
soil burial. ' However, this finish is subject to chipping and abrasion
when handled, so that it must be assumed that all buried containers will have
holidays (bare spots) in their external coatings.
Coatings are applied for their protective qualities. However, in
the case of underground burial, coatings often accelerate pitting. For
example, it has been observed that bare pipelines buried in a mildly corrosive
soil may start to perforate after 10 to 12 years' service whereas coated pipe-
lines with no additional protection might perforate in 5 to 6 years. In part,
this is the result of long-range galvanic effects over considerable spans of
pipeline, which would not be expected to he so severe over the relatively
short distances involved with individual electrically isolated 55—gallon drums.
However, the coating itself frequently is cathodic to the exposed metal so that
a strong galvanic driving force exists between the large cathodic surface area
of the coating and the small anodic area of bare metal at holidays. This
condition can lead to rapid pitting at the small bare areas.
Not only does handling break the lacquer film on the drum, but dent-
ing can cause increased corrosion of the steel. "Work performed at Los Alamos
has shown an increased rate of corrosion at stressed areas resulting from minor
, , . .. (19)
damage such as denting.
Thus, in considering the performance of buried lacquered drums with
holidays, it must be assumed that they will probably perform no better in
the hurial environment, than bare steel with respect to penetration by pitting.
However, overall corrosion (metal loss) would be expected to be less on the
lacquered drums.
At first glance, a small pit through a container might not be con-
sidered to be a serious problem since migration of the contents into the soil
would depend on diffusion outward through the hole via a liquid or gas phase.
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However, if a liquid penetrates the container, the same slow diffusion
processes can be expected to contribute to the enlargement of the pit and
increased attack on the inside of the drum. This would be particularly true
where the soil is well aerated. Inside the drum, the oxygen supply would
become depleted in the liquid because of the slow diffusion through the small
hole. This would result in a galvanic cell with the depleted oxygen region
being the anode (corroding area) while the well-aerated external surface
would be the cathode (noncorroding area). Thus, once the container is pene-
trated by a pit, its deterioration by corrosion can be accelerated.
The corrosive characteristics of a number of soils have been deter-
mined on bare steel pipes in studies conducted by Romanoff . Corrosion
data are presented for some seventy soils. Corrosion rates varied from
0.06 mil/yr for gravelly sandy loam to 6.0 mils/yr in high-alkali clay;
corresponding maximum pit depths for these two soils were 20 mils In 17,5
years and >251 mils in 4 years, respectively. As indicated earlier, pre-
dictions of corrosion performance from known behavior in a given soil to
that in a similar soil are frequently not reliable. Nevertheless, corrosion
data from Romanoff for steel pipe buried in soils with conditions similar
to the present shallow land burial sites in the United States show maximum
pit depths of 40 mils or greater in 2 years. This indicates that steel
drums buried in similar soils may be penetrated by pitting in a few years.
Corrosion by Seawater
Seawater. is more uniform in composition than soil at various loca*-
tions on the earth, nevertheless, the corrosivity of seawater can vary
depending on oxygen content, marine life, temperature, and contamination.
Dissolved oxygen content is the most critical variable in corrosion by sea-
water. Corrosion under the conditions of neutral to very slightly alkaline
salt solutions is dependent on the availability of oxygen to depolarize the
cathode reaction. Thus, in general, as oxygen content increases, the corro-
.sion rate increases. Furthermore, oxygen concentration cells are very active
in seawaters because of the high conductivity of the medium. Thus, a small
deposit of sand or an occasional marine growth can result in rapid pitting
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13
because of oxygen depletion beneath the covered area as explained earlier.
Steel components partially embedded in mud would corrode below the mud line
for the same reasons. It is true that the dissolved oxygen concentration at
depths is lower than on the surface, but the oxygen concentration does not
necessarily decrease progressively with depth. For example, oceanographic
data obtained at a sate west of Port Hueneme, California, reveal a rapid
decrease in dissolved oxygen from ^6 ppm at the surface to ^0.2 ppm at 2000
feet, but with a subsequent gradual increase to 'vl.S ppm at 5600 feet.
Biological activity, as mentioned earlier, can promote pitting and
reduce oxygen levels where large quantities of biota live (and die) in rela-
tively shallow waters.
Temperature has a complex effect on corrosion. An increase in
temperature normally increases chemical reaction rates and increases
biological activity, both of which will increase corrosion attack. On
the other hand, an increase in temperature decreases oxygen solutility
and causes increased precipitation of calcium carbonate and magnesium
hydroxide as calcareous scales. Both phenomena can "increase resistance
(21)
to corrosion attack.
The corrosion rate and pitting rates of steel in seawater decrease
with time. The overall general corrosion rate in shallow water drops to
^5 mil/yr after 1 year, but does not go much below 3 mil/yr with continued
(22 23)
exposure beyond 1 year. In these same studies, the pitting of carbon
(23)
steel averaged ^60 mil penetration after 4 years and 'vSS mil after 16 years.
Maximum pit depth was 155 mil after 16 years.
At depths, of the order of 5600 feet, the overall corrosion rate of
steel is M. mil/yr or about one-third that at the surface.'^u' However,
pitting rates at depth, particularly in crevices, are not greatly different
from those at the surface. Since most ocean disposal is expected to be at
great depths, say not less than 13,000 ft, one could expect a conventional
55-gallon drum to perforate by pitting at holidays in the coating as rapidly
as 4 years.
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14
Corrosion by Contents of the Container
Corrosion of the inside of the steel drums by the contents is also
a possible mode of perforation. In general, the inside surface will not be
corroded if moisture is absent (relative humidity <70 percent) . If a liquid
phase is present, the extent of corrosion can be controlled by adjusting the
pH of the contents (prior to closing) to pH 10-11, the optimum pH for the
(24)
resistance of steel to attack. However, certain plastics -such as poly-
vinyl chloride (PVC) can degrade by radiolysisv ' or heat (>7Q C) to form HCl
which, in turn, would attack the inner steel surface.
Increasing the pH to 10-11 may not be effective if the drum can
breathe so that it has access to a fresh air supply. Under these conditions,
neutral or alkaline chloride solutions can promote pitting in much the same
manner as in seawater, because there is an ample supply of oxygen to depolarize
the cathodic reaction in the corrosion process. On the other hand, if the drum
is airtight, the oxygen supply would soon be exhausted, and the corrosion
attack would be stifled. The effects of increasing the pH may not be of
long duration if radiolysis of the contents can produce acidic products.
Discussion of Corrosion of Metal Containers
It is readily apparent from the preceding discussion that perforation
of 55-gallon steel drums by corrosion of the external surface is a strong prob-
ability in either land or ocean- disposal unless extra precautions are taken.
(Perforation due to corrosion by the contents is also a possibility, but may
be controlled to a reasonable level by appropriate measures.) Conversely,
individual drums may survive burial or an entire burial site may not be corro-
sive. Unfortunately, corrosivity cannot be predicted with any degree of
consistency in soils and, similarly, the conditions that limit corrosion in
seawater — such as complete biological fouling or buildup of calcareous
deposits — -also cannot be predicted. Thus, relatively long-term corrosion
studies are needed at each burial site (including the deep ocean) to develop
a predictive capability.
Of course, extra protective measures can be employed. For external
corrosion, these would consist of thicker, more resistant, and more tenacious
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15
coatings plus sacrificial anodes such as zinc. Even under these conditions
an occasional failure may occur when anodes are broken loose because of rough
handling, when anodes are rapidly consumed because of large exposed bare areas
on the external portion of the drum, or when anodes become completely covered
with heavy biological fouling.
For soil burial, a heavy plastic cover over a number of drums sup-
ported on a pad may effectively reduce corrosion, but, again, 100 percent
integrity cannot be assured because of damage during handling operations and
uncontrolled factors such as shifting of the soils while settling.
Controlling corrosion by the internal environment can be effectively
carried out if proper control can be maintained over the packaging operation.
Depending on the severity of the corrodant, a number of measures can be taken,
such as; dry packaging with desiccant to minimize moisture; volatile ainine
vapor phase inhibitors for high-humidity, low-corrosivity conditions; neutral-
ization and pH adjustment to 10-11 for liquid environments; and heavy linings
for liquid environments, but avoiding P¥G or other unsaturated chlorinated
polymers to preclude HC1 generation by radiolysis.
In conclusion, breaching of the steel drums can be minimized by
using protective measures (in addition to the usual lacquer on the drums),
that are tailored to the specific environments inside and outside the drums.
However, 100 percent integrity probably will never be achieved because the
drums must be handled by mechanical means, and once buried, are at the mercy
of the stresses of soil movement or ocean currents.
Decomposition of Wood Containers in Soil
The decomposition rates of wood are determined primarily by three
conditions: (1) the temperature-moisture regime; (2) characteristics of
woody material; and (3) population density of decomposing organisms, espe-
cially arthropods. Storage of materials in wood containers in soil can be
expected to be effective for a finite time period (5 to 25 years) depending
/ *) f.\
on the three sets of conditions listed above
There are two major modes of wood decomposition in soil: linear
wood degradation and logarithmic degradation rates. Linear wood degradation
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16
rates are the initial stages of breakdown. Under high soil moisture conditions
and temperatures >4 C, a rate of 1 to 8 percent loss over a period of a year
can be expected. During this time, carbon is selectively lost from wood while
nitrogen, phosphorus, and other nutrients are accumulated. When nutrients have
accumulated to a threshold level, decomposition rates of wood will increase
rapidly and may approach a logarithmic function for a finite period of time, 6
to 12 months, until nutrient supplies are exhausted.
In general, wood decomposition rates are stimulated by:
(27)
Temperature-moisture regimes
• Minimum freezing conditions
* Moisture >50 percent dry weight in soil
* Constant moist conditions.
(28 29)
Characteristics of woody materials *
• Low density
• High homogeneity of wood types used in
materials such as particle board
* Detectable nitrogen and phosphorus
concentrations
* High water holding capacity.
Population density of decomposing organisms
* Presence of orthropods which colonize wood,
e.g., termites, ants, psalid beetles,
dipteran larvae
• Presence of fungal and bacterial populations
(31)
which colonize cellulose substrates
It is possible to attenuate wood decomposition rates by using mate-
rials of diverse wood types, impregnated with creosote or other high-molecular-
weight organics, and burial at depths greater than the normal "biotic" zone of
the soil. Choice of soils which are well-drained, nutrient depleted, and
droughty will also allow longer stability of wood containers.
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17
3.2 Effects of Radiation Damage,to Waste Packaging
The radiation damage to solidified low-level wastes is of interest
for several reasons. The decomposition products are generally gaseous and
can cause internal pressurization of the waste containers or may produce
explosive mixtures within the containers. Some decomposition products may
be corrosive and affect the container life. Radiation damage may cause a
deterioration of the solidifying or fixation agent, making the radioactive
species more susceptible to transport.
At present, information is insufficient to make a quantitative
assessment of all of the radiation effects on solidified wastes. However,
the current literature shows some progress is being made particularly in
reference to the gas release and equilibrium pressures anticipated for
particular wastes. The following discussion is intended to place the problem
in some perspective.
Commercial light water power reactors can he expected to be a major
source of low-level wastes in the future. The liquid wastes from reactors
are concentrated and appear as evaporator bottoms, filter sludges, or ion
exchange resins. They are generally consolidated in one of several forms for
disposal. The most common solidifying agents are usually based on cement or
plaster, a polymer such as urea formaldehyde, or bitumen,
Effect,of Composition
To qualitatively predict the radiation effect (damage) on the waste
composite due to incorporated radionuclides, it is necessary to know the
composition, the amount of various isotopes, and size and geometry of the
container. All of these can and do vary from one waste form to another. For
instance, the properties of bitumen vary depending on grade, as does a com-
posite based on a cement. The solidified waste composition also varies with
the amount and kind of waste incorporated, i.e., filter sludges, evaporator
bottoms, etc. However, for this general discussion the folloxdng observations
can be made. The radiation dose to the solid waste is a function of its
density and its radiation absorption coefficient. Most of the waste forms of
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18
concern are composed largely of the lighter elements, hydrogen, oxygen, carbon,
silicon, magnesium, aluminum, calcium, etc. Thus, the overall mass absorption
coefficient will not vary greatly from one form to another. Nor does the
density of the waste forms vary greatly. Thus, for this approximation, an
average absorption coefficient and density were assumed for all waste forms of
interest.
Radiation SQurc_e_andEstimated Dose
The kinds and amount of radionuclides vary with the nature and
origin of the waste. As a basis for estimating a typical radiation source
(32)
term one published tabulation of concentrations of radioactive materials
in solid wastes from light water reactors has been utilized. Although
tritium is shown to be abundant in these wastes, from the standpoint of
radiation effects, it is a small source of absorbed energy (the emission
is a very weak beta). Several other isotopes can also be disregarded even
though they represent several percent of the radionuclides produced. For
example, Cr has a short half-life and Mn has a low total energy. From
the standpoint of radiation effects, three isotopes provide most of the
energy, Co , Cs , and Cs . For this study, it was assumed that these
three isotopes formed a representative radiation source for low-level
wastes. Gamma radiation is the major source for these three isotopes
but the accompanying betas make a significant contribution to the absorbed
dose rate.
In estimating the absorbed dose rate, it is assumed that all the
beta energy is absorbed. To estimate the dose rate from the gammas an
(33)
expression for self-generating, self-absorbing infinite cylinder was used
The diameter of the cylinder was taken to be that of a 55-gallon drum and the
activity of the composite was assumed to be 4.7 yCi g Co ,3.3 pCi g Cs ,
-1 134
and 2,00 yCi G Cs . This represents a typical total specific activity and
a distribution of the three isotopes as they would be expected to be formed in
light water reactors.
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19
Radiation Effects.
There is little quantitative information on the acceptable radiation
dose to the different waste forms. For example, for bitumen, the dose at which
8
radiation damage becomes significant is reported to be in the range of 10 to
9 (34)
10 rads. Holcomb states that depending upon the type of bitumen, doses of
10 rads from internal radiation are acceptable. Sousseller states that
Q
doses to 10 rads are required for significant radiation damage,
Colombo and Neilson have studied the gamma irradiation of
5 9
cement, urea-formaldehyde, and bitumen at exposures from 10 to 10 R.
They report that, the radiolytic gas generation from all three matrix
materials is a function of exposure rate. They observed that the gas
production increases at a given exposure as the exposure rate decreases.
However, for a given exposure time, the higher exposure rate generally
resulted in a larger gas release. The quantity of gas evolved per unit
energy input, G value, to the urea-formaldehyde matrix was an order of
e Q
magnitude greater over the exposure levels from 10 to 10 R than that of
cement. G values for bitumen were not obtained at the lower exposures,
7 R
but at 10 and 10 R, the values for bitumen were significantly less than
9
for cement. However, at 10 R the G value for bitumen was greater than
those of cement and urea-formaldehyde which may indicate a threshold for
more rapid deterioration.
(37)
Work reported by Bibler and Orebaugh shows the effects of dose-
rate and total dose on the gas production during the irradiation of concrete
by gammas from cobalt-60 sources. The gas produced is predominantly hydrogen
from the radiolysis of water. They observed that the calculated number of
hydrogen molecules produced per unit of energy absorbed in the concrete , G
value, was constant and independent of dose rate over the range studied,
Thus it is believed that the data can be related to the lower dose rates
typical of low- level wastes. When the irradiation of concrete was conducted
in a closed system, it was observed that in time an equilibrium pressure was
reached and the pressure was proportional to the dose rate. This indicates
the presence of a competing reaction for the removal of hydrogen. Below
10 rads/hr the equilibrium pressure was insignificant; at 10 rads/hr
approximately one atmosphere was measured.
The above study also included the irradiation of two organic fluids
adsorbed on vermiculite. The gas evolved in these irradiations was mainly
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20
hydrogen with small amounts of carbon dioxide and methane. Here no equilibrium
pressure was reached with either fluid and the G values varied with dose rate.
This indicates that higher pressures from dissociation may be expected from
the radiolysis of organics than from water.
Figure 1 shows the estimated dose rate over a 10-year period for the
assumed source term from light-water reactor waste described above. This shows
that the dose rate is less than that which would be expected to produce a
significant overpressure of hydrogen from the radiolysis of water in concrete.
The estimated dose for a period of 10 years is shown in Figure 2. This is well
below those anticipated to cause significant damage to any of the waste forms
under consideration. However, it is reasonable to believe that in isolated
cases low—level waste forms may be generated (by incineration or other volume
reduction methods) with specific activities significantly greater than what
is cited here as typical. If wastes had activities of tens of millicuries
4
per gram and have dose rates over 10 rads/hr, they may produce exposures
9
in the order of 10 rads in 10 years. At this higher dose, the gas produced
by radiolysis can approach the pressure limit of some containers and the
total dose may cause some degradation of the matrix in 10 years. Levels of
hydrogen produced by radiolysis can reach potentially explosive mixtures
with contained air but is not a major concern with small void volumes and the
lack of ignition sources. The radiolysis of chlorinated hydrocarbons (PVC)
can release chlorides which may promote corrosion of internal surfaces of the
containers.
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21
1000 F
100 -
Total
137
CO
t)
co
M
'10
134
4 6
Time, yr
10
FIGURE 1. APPROXIMATE DOSE RATE IN WASTE CONTAINERS WITH
4,7 yCi/g Co60; 3,3 pCi/g Cs137; .2.00 pCi/g Cs134
10
tu
g
p
•d
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22
3.3 Structural Effects of Waste Containers
Structural Characteristics of
Waste Containers
A definitive analysis of the structural properties of waste con-
tainers is beyond the scope of this study, and with such a variety of
containers in use, only a general discussion is appropriate. As discussed
previously, the general structural standards for containers for shallow land
/-j o\
burial result primarily from the DOT and NRG regulations ' for safe trans-
port of the,materials with possibly some additional requirements imposed by
the waste generating or waste burial operators. For low specific activity
wastes, the container structural requirements may be limited to the general
requirement for strong, tight packages. A container for burial which is also
an approved Type A packaging must retain its contents and effectiveness of
packaging when exposed to the defined normal conditions of transport
(49CFR 173,398). From a structural standpoint, the most severe of these
conditions is • usually considered a free fall of four feet onto a flat unyield-
ing surface or the penetration resistance from a 13-pound, 1.25-inch-diameter
bar falling 40 inches with its axis perpendicular to any surface. Whereas
a Type B container must meet additional more stringent requirements, these
containers would seldom, if ever, be used as the disposal container. Rather,
a waste container for greater than Type A. quantities is transported in Type B
packaging but removed tot burial. This type of waste container may not have
the structural capacity of Type A packaging.
The structural requirements for containers for ocean disposal are
(14) •
better defined. The guidelines state that the packaging should retain
the contents until after it is deposited on the ocean floor. Here the major
concern is the collapse of the container under the increasing hydrostatic
pressure during submergence. The container is assumed to be unable to sustain
the stress of the pressure and must either be supported by incompressible
contents or the container must leak to equalize the pressure to avoid exces-
sive stress.
Inasmuch as the 55-gallon drum is the most commonly used container
for waste disposals the structural capacity of this container is pertinent.
The DOT 17-H steel drum specification defines the type of material, thickness
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2-3
for side wall and heads, design of closures (bolted head ring or threaded
plugs), minimum number and location of rolled or stamped hoops or corrugations,
and type of seams. These specified features largely define the structural
capability of the drum. In addition, the specification requires the producer
of the drum to perform tests on a drum taken at random from production every
four months. The drum is to be closed as for use and experience the tests
without leaking. The tests include dropping a water-filled drum from a height
of four feet onto a concrete surface in a manner to impact on its chime or
circumferential seal. Also, the drum is to sustain a hydrostatic pressure of
15 psi for 5 minutes. (A specification DOT 17C drum has a thicker side wall
and requires a pressure test of 20 psi for a removable head, or 40 psi for a
/"}Q S
fixed head drum.) Hydrostatic testing by BNL show that whereas these leak
tests may be achievable, they are not necessarily routinely obtained. Recog-
nizing this, some users have specified more frequent testing in their orders
as a condition for acceptance.
These specifications are intended to assure some minimum degree of
integrity for packaging during transport but there is no obvious assurance
of acceptable performance as disposal packaging. The structural loads which
a disposal container is expected to experience are largely those which occur
from differential pressures or those from Impacts. Internal pressures may
result from radiolytic decomposition of the waste, but as discussed previously
this will require higher radiation levels than expected in most low—level
waste containers. Internal pressures may also be caused by physical or chemi-
cal reactions within the contents. For example, the swelling of resins upon
(39)
exposure to water has been reported to cause stresses which have pulverized
the concrete matrix and burst the container. Structural loads from external
pressures may be most significant during the disposal process for land burial
as well as sea burial. For ocean disposal, the hydrostatic pressure 'is the
dominant structural load to the container. For shallow land burial, the weight
of the back fill soil plus the weight of backfilling equipment may cause loads
of a few 10's of psi on the containers. Although these structural loads from
differential pressures may be significant, more structural damage should be
expected from impact loads.
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24
The DOT specification 17C or 17H drum is required to sustain a. drop
of 4 feet onto concrete without leaking. With the small design margin which
can be expected for such containers, we may assume that if they are subjected
to greater impact loads they will suffer sufficient damage to leak. It can
3
be shown by calculations that a water-filled large container (170 ft ) with
up to 1/4-inch-thick walls or a water-filled 55-gallon drum will be punctured
by falling less than 4 feet onto a fixed steel post with a diameter of up to
8 in, unless the contents absorb a large part of the impact energy. These
statements are intended to place in perspective the magnitude of structural
loads from impacts which may be expected to cause the failure of a container.
It must be recognized that during disposal by land burial most
containers will be dropped from heights greater than 4 feet unless they are
individually, or in small lots, lowered into position in the burial trenches.
It does not mean that every container dropped from greater than 4 feet will
fail. It does indicate that waste containers dropped from 20 to 30 feet and
impacting on a solid object such as another container will have a high proba-
bility of failing, or causing another to fail. During a discussion at a
recent conference it was stated that in some operations approximately
half of the containers were ruptured during the disposal operation. This is
not a criticism of disposal operations since by present objectives the con-
tainer has completed its role when buried and no further retention is required
of it.
In summary, it is evident that waste disposal containers are very
susceptible to structural damage which can cause them to fail during or after
the disposal operations. If a container is dropped so that it impacts a
solid surface or another container, it can burst or puncture. Bormal handling
operations may scrape through protective coatings exposing bare metal to
pitting-type corrosion after disposal. Small dents in a container may result
in accelerated stress corrosion after disposal. The loads from the weight of
backfill soil and a bulldozer on a burial trench may crush a container wall
which is not supported by the contents. Higher than average specific activity
in the waste can produce internal pressure by radiolysis to cause a container
to leak.
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25
Observed Structural Performance
of Waste Packaging
The conclusions of these assessments of the effects of corrosion,
radiation damage, and structural damage are largely supported by the inspection
of containers after extended periods of burial. Dyer reports on the
observed conditions of 55-gallon steel drums 21 to 23 years after disposal on
the sea bed at 3000 ft depth. The most common mode of failure was hydrostatic
crushing of the drum as wastes had been compressed; there was no evidence of
pressure equalization devices. All drums showed evidence of surface .corrosion
but the metal was generally sound; black sulfide deposits indicated a deficiency
of oxygen in the region. Drums which had been breached showed greater deterio-
ration as corrosion could occur internally and externally. The reports of
the condition of packaging retrieved from shallow land burial in Idaho show
that drums which had been buried in a stacked array for up to 18 months were
in generally good condition although some had leaked. Barrels buried from
3 to 7 years by random dumping into the pit showed damage that had occurred
during dumping and evidenced contamination levels one order of magnitude
higher than from those buried for 18 months by stacking. Barrels buried for
12 years by stacking in pits were in poor condition due mainly to corrosion.
A plywood box buried for 5 years was in poor condition; cardboard boxes buried
(41)
7 years had disintegrated. In other drum retrieval operations at Idaho
it was reported that all drums recovered after 5 to 6 years of burial showed
visible rusting of the surface but less than 2 percent were observed to be
breached or were without lids. Observations during retrieval operations
ft f\ \
at Savannah River have led to the conclusions that cotton cloth, paper,
and wood buried in water-unsaturated soil at that site will require decades
to completely decompose.. It is believed this low rate of decomposition
results from a deficiency of oxygen.
In summary, these discussions and observations show that little
benefit can be expected in the retention of low-level wastes after disposal
by the containers which are presently in use. If the container survives the
structural loads imposed in handling and burial operations, its life in the
disposal environment will be limited to a few years by corrosion, Radiolytic
effects to the contents will be a secondary effect in the life of the container.
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26
4.0. TYPICAL LOW-LEVEL,,WASTE PACKAGES
Four waste packages have been identified as typical of current prac-
tices and are presented here for discussion. One package representative of
those for sea burial and three systems for shallow land burial are described
in Table 1.
TABLE 1. DESCRIPTION OF FOUR TYPICAL WASTE PACKAGES
Package Container Coating Liner
A 55- gal Ion Drum Paint None
(DOT 17C)
B 55-gallon Drum Paint "None
(DOT 17H)
3
C Large, 178 ft None None
Steel Container
D Fiber Drum None Polybag
Waste
Matrix Type
Bitumen PWR Filter
sludge
Cement BWR Evap .
"bottoms"
None PWR Resins
None Trash
Burial
Made
Ocean
disposal
Shallow
land
Shallow
land
Shallow
land
It is believed that there will be a large degree of commonality in
the performance expected of these packages when exposed to their respective
disposal environments. Package A is believed typical of those recently dis-
posed of by deep sea burial by the European Community, The bitumen matrix
with up to 50 volume percent waste would offer an incompressible support for
the drum container; this would be classed as a monolithic package and would
not require a pressure-relief device. The -monolithic design will be more
resistant to structural damage during all handling operations than a container
with compressible contents. The specific activity of the waste should be less
than that which would cause radiolytic deterioration of the matrix for extended
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27
periods. Although corrosion rates may be low and allow long container life
(over 20-year life times have been observed), other corrosion data, Section. 3.1,
would indicate that loss of containment could occur in a short time period (four
years or less),
Package B is typical of much of the low-level waste disposed of by
shallow land burial. Cement or concrete is a commonly used matrix for solidi-
fication, fixation, and/or shielding; it may contain 25 volume percent waste.
Some excess water may be released from the matrix and be an available internal
corrodent. The steel drum container gains structural support from the concrete
matrix and is less vulnerable to puncture. In the event of severe damage
during handling, such as loss of the cover, the matrix will limit dispersal
of the waste to the atmosphere. The container life after disposal will be
limited to a few years or less by corrosion. The paint will not be effective
in promoting the container life; whereas general corrosion may be reduced,
localized pitting may be accelerated. Upon loss of containment, radionuclides
will be available to be leached from the matrix and released to the soil.
Package C is representative of newer systems being used to dispose
of large volumes of waste from commercial light water power reactors.' The
large container is made of mild steel by welded construction and may have a
1/4-inch-thick wall. The ion~exchange resins are assumed to be loaded into
the container by being combined with enough water to form a slurry capable of
being pumped. After filling, the excess water is removed from the container
by draining or by being pumped out through a dip tube. This container will
be transported in a Type B overpaek which will offer it protection from struc-
tural damage during this phase. However, the contents do not provide the
rigid support of cement or bitumen and the container will be more susceptible
to damage by localized impacts. Although it has a heavier wall, the larger
surfaces and greater total weight give it only slightly more resistance to
puncture than the thinner wall steel drum with similar contents. After burial,
with other factors being equal, the life of the thicker walled container should
be proportionally longer than a. thin-walled container. The lack of paint or
other coatings will permit general corrosion, but will not encourage localized
pitting. The damp contents may promote corrosion of the internal surfaces,
particularly if the pH is low, but depletion of oxygen in a sealed container
may limit the reaction. After loss of containment, the large surface area of
the contents will promote release of the radionuclides to the soil.
-------
28
Package D is representative of a class of packaging which would
include wooden and cardboard boxes as well as fiberboard drums. These are
more typical of low-level waste packaging at government laboratories which
also operate a burial ground. Where public transportation systems are not
required, the waste packages may be carried in a dumpster from a lab area
where they are packaged and dumped directly into a burial pit. The trash
waste includes contaminated paper, rags, plastic tubing, glassware, tools,
etc,, which are collected in a plastic bag. The bag is taped closed prior to
being inserted into the fiberboard drum. The drum is then sealed with tape.
The light weight and small size of the containers make them less sensitive to
structural damage than large containers although they may be punctured by
sharp objects. The life of these containers after burial is expected to be
short, several months to a few years, depending upon soil conditions. However,
the plastic bag may retain the contents for longer periods.
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29
5.0 RECOMMENDATIONS
There is an increasing involvement of Federal agencies in low-level
radioactive waste disposal as well as the management of all nuclear wastes.
A DOI Task Force^ ^ has recommended that DOE assume the responsibility for
the management of the six commercial waste burial grounds in addition to the
Government-owned sites in order to strengthen technical capabilities and
operating practices by the application of research and development, and to
develop criteria for carrying out responsibilities of the program. An NS.C
trds
(45)
Task Force has concluded there is an urgent need to establish standards,
criteria, and regulations governing low-level waste management. The EPA
has taken initial steps to recommend environmental protection criteria to be
used for the development of environmental standards for radioactive waste
management. Somewhere in this evolving process it will be necessary to
establish criteria for the performance of the packaging for low-level waste
disposal and regulations and standards can then be developed to meet the
criteria. It is apparent that there is presently a void in the general
control of low-level waste packaging. However, to fill this void with prac-
tical and effective controls will require a significant study effort,
Extensive further research is needed to define the mechanisms for trans-
port of various nuclides in specific shallow land burial environments, to
define optimum waste forms which will be long lived and limit mobility of
the wastes, and to specify packaging which will maintain its integrity
through the stresses imposed by the disposal operations and will have a
low rate of corrosion to allow long container life. More information is
needed to describe the relative roles of the burial soil (or ocean bottom),
the waste form, and the packaging as barriers to the transport of radio-
nuclides. It can only be through a better understanding of these roles
that a cost-effective approach can be made to limiting the migration of
nuclides. The economics of waste disposal will always be a consideration
as it is the general public who must ultimately pay the cost.
Improved packaging must consider all aspects of the problem
including the waste composition, the final waste form, the container
structural design, the container materials, the handling operations, the
burial environment, the desired performance of the total system, and the
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30
acceptability of the cost. The following areas are recommended for con-
sideration.
(1) The packaging can be more effective if the material to be
contained is defined. There is need to classify the wastes according to
the nuclide content for effective containment. This classification among
other things, should consider half-life, mobility, and the imposed risk to
the environment. For example, tritium, or tritiated water, may be considered
a class by itself because of high mobility and great abundance as a waste
product so that special barriers may be utilized to restrict its entry into
the environment. Also, different barriers would be effective for fission or
129 135
activation products with half-lives of several years than for I , Cs
or some actinides with half-lives of thousands of years.
It must be recognized that wastes are not produced in convenient
classes but are usually complex mixtures. . Although it may be possible to
segregate various nuelides in some waste collection processes, segregation
may be impactical or uneconomical in most processes. In the latter case
classification of wastes may be necessary on the basis of the dominant
characteristic of the mixture. For example the waste may be classified
on the basis of the longest half-lived or most environmentally hazardous
component with some consideration for relative concentration.
(2) An effective barrier to migration is the form of the waste.
Increasing degrees of inertness or insolubility of the waste form will tend
to decrease mobility. Certainly a solid waste form is less mobile than a
liquid and whereas solidification of wastes-is a general requirement, there
should be a better definition of acceptable solids. If absorbed liquids are
to be permitted, there should be a better definition of acceptable absorbents,
and acceptable liquid/absorbent ratios. Preferably all wastes will be solidi-
fied by removal of the liquid phase, or chemical binding of the liquid.
Currently, cement, plaster, bitumen, and polymerized resins are used as a
matrix for solidifying wastes. These same materials are also used for fixa-
tion of dispersable solids. Although studies are in progress to characterize
various formulations of these materials, more efforts should be applied to
the study of solidification or fixation agents to define acceptable materials
and relative quantities of waste in the matrix to achieve optimum thermal,
radiolytic, and structural stability of the waste form. Consideration should
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33
(6) In summary, it is recommended that criteria be developed for
the required retention of various classes of radionuclides for environmental
protection. Within that scope, the potential roles of different barriers
should be defined. From this base criteria may be developed for each of
the barrier systems, i.e., waste form, packaging, etc. Regulations can
then be developed in response to these criteria. Finally, standards may be
prepared which will show acceptable methods of complying with the regulations,
It would appear that EPA has the prime responsibility to develop the
performance criteria for the disposal method in terms of defining allowable
release to the environment and to develop criteria for monitoring the
performance of the disposal site. For ocean disposal EPA presently has
authority for waste packaging criteria.
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34
Ac kno wl ed grnen t s
This report was compiled by Neil E. Miller of Battelle, Columbus
Laboratories, BCLS with significant contributions made by
Beverly S. Ausmus, BCL
Michael E, Balmert, BCL
Warren E. Berry, BCL
Richard J. Burian, BCL
John F. Kircher, BMD (formerly BCL)
Elmer C. Lusk, private consultant (formerly BCL)
Francis A, O'Hara, BCL.
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35
6.0 REFERENCES
1. "The Shallow Land Burial of Low-Level Radioactively Contaminated
Solid Waste", National Academy of Sciences; Washington, B.C., 1976.
2, "Alternatives for Managing Wastes from Reactors and Post-Fission
Operations in the LWR Fuel Cycle"; ERDA-76-43; Vol. 4; pp 24.1-24.49;,
May, 1976.
3. Holcomb, "W. F., "A Summary of Shallow Land Burial of Radioactive
Wastes at Commercial Sites Between 1962 and 1976, with Projections";
Nuclear Safety, Vol. 19; No. 1; p 50; 1978.
4. Dieckhoner, J, E., "Sources, Production Rates and Characteristics of
ERDA Low-Level Wastes" presented at the symposium "Management of Low-
Level Radioactive Waste"; Atlanta, Georgia; May, 1977.
5. Dyer, R, S., "Environmental Surveys of Two Deepsea Radioactive Waste
Disposal Sites Using Submersibles", IAEA-SM-207/65, 1976.
6. Oliver, J. P., "Sea Disposal Practices for Packaged Radioactive
Waste", Proc. International Syrup, on the Management of Wastes From
the LWR Fuel Cycle; Denver, Colorado; CONP-76-0701; p 667; 1976,
7. Title 49 Code of Federal Regulations, Parts 170 to 199, Department
of Transportation, Regulations for the Transport of Hazardous Materials.
8, Title 10 Code of Federal Regulations, Part 71, Nuclear Regulatory
Commission, Regulation for the Packaging for Transport of Radioacti,ve
Materials.
9. Jefferson, R. M., and Bonzon, L. L., "Available Packaging and Trans-
portation Systems"; Proc, International Symposium on the Management
of Wastes from the LAR Fuel Cycle; Denver, Colorado; CONF-76-0701i
p 448j 1976.
10. Personal communication from E. S. Goldberg, Savannah River Operations
Office, to R. J. Burian, Battelle-Columbus Laboratories.
11. "Final Environmental Impact Statement, Waste Management Operations,
Savannah River Plant, Aiken, South Carolina"; ERDA-1537; p 11-122;
September, 1977.
12, "Final Environmental Impact Statement, Waste Management Operations,
Idaho National Engineering Laboratory, Idaho"; ERDA-1536; p 11-165;
September, 1977.
13. Wickland, C. E., "Packaging Rocky Flats Waste"; Nuclear Technology;
Vol. 32; p 25; January 1977.
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36
14. "Guidelines for Sea Disposal Packages of Radioactive Waste";
Organization for Economic Cooperation and Development, Nuclear
Energy Agency; Paris; 1974,
15. Title 40 Code of Federal Regulations, Part,220, Section 227.11,
Environmental Protection Agency, Regulations for Ocean Dumping of
Waste,
16. Romanoff, M., "Underground Corrosion", U.S. Department of Commerce,
National Bureau of Standards Circular 578; April, 1957.
17, Colombo, P., and Neilson, R. M., Jr., "Properties of Radioactive Wastes
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