1. No category

Naturally Occurring Radioactive Material (NORM) and
Technically Enhanced Radioactive Material (TENORM)
April 12, 2015
by
NORM Workshop Presenters
NORM and TENORM: Occurrence, Analysis, Methods, Monitoring, Handling and
Disposal – R&D Needs
5/12/2014
and
The NORM Working Group at The Ohio State University
Authors: See acknowledgments on page 20
Contact: Jeff Daniels, Director, Subsurface Energy Resource Center
http://serc.osu.edu/
i
The Ohio State University
INDEX
Executive Summary ................................................................................................. 1
Naturally Occurring Radioactivity ....................................................................... 3
Ionizing Radiation and Radioactivity ....................................................... 3
Background Radioactivity and Radiation ................................................ 5
Radon as Background Radiation ............................................................... 7
Summary of Natural Background Radiation Doses ................................ 8
Rocks and NORM ................................................................................................... 9
The Formation of Sedimentary Rocks Bearing Hydrocarbons and
Radioactive Materials – Appalachian Example ....................................... 9
Rocks and Radioactivity .............................................................................11
Radioactivity in Shale .................................................................................12
NORM in Unconventional Oil and Gas Production ............................................13
TENORM in Unconventional Oil and Gas Production .......................................15
Operational Framework for Handling NORM and TENORM .........................16
Conclusions ..............................................................................................................18
Acknowledgments ...................................................................................................19
References ................................................................................................................20
APPENDIX - Basics of Radioactivity ....................................................................21
ii
Executive Summary
Naturally Occurring Radioactive Material (NORM) is any terrestrial material (rock, soil, water)
that contains radioelements that emit radiation. Technologically-Enhanced, Naturally-Occurring
Radioactive Material (TENORM) is produced when activities such as uranium mining, or
sewage sludge treatment, concentrate or expose radioactive materials that occur naturally in ores,
soils, water, or other natural materials (US EPA). Radiation from extraterrestrial and terrestrial
sources is ubiquitous in our environment. NORM occurs at the surface and in the subsurface in
shale and some other sedimentary rock formations throughout the U.S. Most of the rocks in the
earth contain some amount of 40K, uranium and thorium, as well as the radioactive daughter
products of the uranium and thorium decay series. Geologic strata that frequently contain
elevated NORM concentrations include: coal seams, phosphate-rich marine deposits, some
granitic rocks, some sandstones, some evaporate minerals (e.g., sylvite and potassium
phosphate), and marine black shale. Any radionuclide in crustal rock can occur in shale. They
may include: 40K, 232Th, 238U, 226Ra, 228Ra, and 222Rn. NORM bearing shale is prominent in
surface rock exposures throughout many regions of the U.S., but the overall mineral composition
of shale and the quantity of radioactive material in shale varies with geographic location.
Naturally occurring radioactive materials may also occur naturally in ground water located near
the surface.
The term NORM has come to be associated with terrestrial materials that emit radiation, but
background radiation also reaches the surface of the earth from solar and cosmic sources.
Radiation that can produce ionization in the media through which it passes can be hazardous to
individuals, and the exposure to radiation is called a dose. Ionizing radiation present in our
natural environment can be classified according to its origin and type, and includes sources as
disparate as solar particles and cosmic rays, and terrestrial radiation from the radioactive decay
of radioelements in the Earth. Determining the hazard potential, or potential dose, requires
considering several environmental factors, including: the type of radionuclides and associated
radiation emitted; where the radionuclides are located and how they are contained; the
environmental pathways (soil, water, air, food, etc.); concentrations and levels or radioactive
materials; the distance and shielding between radiation sources and humans; the modes and
routes of entry for exposure (inhalation, ingestion, or dermal absorption); duration of exposure;
and other factors (e.g., individual or biological factors). Cosmic and terrestrial radiation doses
have been well documented for different regions of the U.S.
The concern regarding hydraulic fracturing is that the radiation dose to individuals from
primordial terrestrial radiation will be increased as a consequence of bringing to the Earth’s
surface radionuclides (NORM) that are contained in shale buried within the earth. NORM from
oil and gas operations may occur as gas, solids, or liquids. Radon gas may appear in methane and
during production off-gassing. NORM may also occur in rock chips created during the drilling
process, or in flowback water.
1
Oil and gas workers and members of the public may be exposed to the radioactive material
derived from unconventional oil and gas development. Exposures of workers are characterized as
occupational exposures and exposures to members of the public are characterized as nonoccupational exposures. Potential exposure pathways for workers may include direct radiation
exposure to contaminated drill cuttings, direct radiation exposure to equipment contaminated
with radionuclides, and inhalation of dust containing radionuclides. For members of the public,
potential exposure pathways could include radon inhalation, dust inhalation from radioactive
material blown offsite, external exposure to radioactive material blown offsite, ingestion of
radioactive material blown offsite, and radiation exposure through the spreading of brine on
roadways, pit abandonment, and brine discharges to land.
The safe handling and disposal of NORM and TENORM begins on site, with the classification
and appropriate handling of drilling waste. The elements of a successful NORM management
practices include: advanced establishment of action limits; detection of NORM at the drill site;
establishing contamination control procedures at a drill site; control and proper handling of
NORM contaminated waste and equipment; and appropriate handling and disposal of NORM
contaminated waste and equipment.
2
Naturally Occurring Radioactivity
Uranium, potassium, and thorium are the most common radioactive materials in rocks and soils,
and these radioactive materials are most frequently contained in clay-stone and shale (both
sedimentary rocks), and in rocks from deep within the Earth (known as igneous or metamorphic
rocks). The most common rocks containing radioactive materials in sedimentary rock formations
occur in carboniferous shale and clay. These rocks are exposed on the surface in many areas. For
example, the Ohio Shale occurs at the surface in various locations in the Columbus area (e.g.,
Hoover Reservoir, Alum Creek Reservoir, along the stream in Whetstone Park, in several deep
ravines that cut across Columbus, Ohio etc.), and shale will occasionally be penetrated by
excavations for buildings throughout the city of Columbus. In Utica New York, the Utica Shale
formation is exposed on the surface – hence the reason for the name of this particular formation;
likewise, the Marcellus formation is exposed on the surface in Marcellus, New York. Naturally
occurring radioactive materials also occur in fresh ground water – fresh water herein is
distinguished as water that is potable and located near the surface as contrasted from deep nonpotable brine. Radiation from extraterrestrial and terrestrial sources is ubiquitous in our
environment.
Ionizing Radiation and Radioactivity
Ionizing radiation is defined as high-energy radiation capable of producing ionization in
substances through which it passes. It includes non-particulate radiation, such as x-rays, and
radiation produced by energetic, charged alpha and beta particles, and by neutrons, as from a
nuclear reaction (American Heritage Dictionary, 2011). Different sources and types of ionizing
radiation exist naturally and are often isolated and enriched by human activities. Research and
clinical cases have confirmed that human exposure to ionizing radiation may result in related
adverse impacts and illnesses. Similar to toxic chemicals, ionizing radiation may result in
adverse biochemical and physiological changes manifested as abnormalities, illnesses, or
premature deaths among individuals or their offspring exposed to sufficiently elevated doses.
Ionizing radiation-related illness can be due to short- or long-term exposures and health impacts
can range from dermal redness, acute radiation sickness, somatic and genetic mutations, and
cancers. Radiation exposure has never been demonstrated to cause hereditary effects in human
populations (UNSCEAR, 2001). Research has also demonstrated that ionizing radiation is
ubiquitous in the environment, primarily from natural sources, and long-term low-level exposure
poses a low risk of radiation-related illness.
Nonetheless, there is justifiable concern for risk of adverse human health effects associated with
both natural and anthropogenic sources of ionizing radiation, but several factors must first be
considered. A primary guiding principle that underlies studies of radiation related human health
impacts is that without human exposure to ionizing radiation there is no exposure hazard. To
3
determine and/or estimate the hazard potential associated with ionizing radiation several
environmental factors must be considered as listed and summarized below.








Types of Radionuclides and Associated Radiation Emitted – Radionuclides vary in many
ways, including their respective decay rates and the penetrability and hazard associated
with the radiation emitted. For example, gamma () rays penetrate materials, including
human tissue, more readily than beta () or especially alpha () particles. Radiation that
readily penetrates the skin ( or ), for example, is an “external” hazard, but other types,
such as  particles, are attenuated by skin and must be inhaled, ingested or injected to
cause systemic effects and are designated as an “internal” hazard.
Sources of Radionuclides and Radiation – Proximity to and containment of NORM
influences its hazard potential; there is typically lower hazard potential associated with
immobilized or more contained forms of radionuclides since they are less likely to be
distributed or spread within the environment.
Environmental Matrices and Pathways of Contact – Soil, water, air, food, products, and
wastes represent various matrices that may be contaminated with radioactive materials.
Contact with these matrices determines the pathway (e.g., airborne) and associated mode
(e.g., inhalation) and route (e.g., respiratory system) involved for potential human
exposure.
Concentrations and Levels – The concentration of radionuclides in a matrix and the levels
and types of radiation (, , or ) may increase the hazard potential and likelihood of
exposure and risk for initiating radiation-related response or illness.
Distance and Shielding Between Radiation Sources and Humans – Increasing the
distance and/or shielding (depending on material e.g., lead vs. wood) decreases the levels
of radiation and potential human exposure.
Modes and Routes of Entry for Exposure – Inhalation, ingestion, and dermal absorption
represent modes and respiratory, gastrointestinal, and dermal systems, respectively, the
corresponding routes of exposure and entry of radiation. For example, inhaled alphaemitting radionuclides may target and adversely impact the lungs, but dermal contact
with alpha-emitting radionuclides may be limited to minor redness or burning of the skin,
depending on levels of exposure. The range of alpha particles in skin is less than the
thickness of the dead layer of the skin (stratum corneum).
Duration of Exposure – When contact with sources of and exposure to radiation occurs,
the risk of initiating an adverse health effect increases with the duration of exposure.
Other Exposure Factors -- When measurable human exposure occurs, other nonenvironmental factors associated with each individual, or biological factors, such as
genetic predisposition to disease, for example, influence the risk or probability of a
radiation-related adverse impact or illness occurring.
Further technical information about radiation is provided in the Appendix.
4
Background Radioactivity and Radiation
Ionizing radiation present in our natural environment can be classified according to its origin or
its type. The National Council on Radiation Protection and Measurements (NCRP) has separated
natural background radiation into four categories: external exposure from space radiation (solar
particles and cosmic rays), external exposure from terrestrial radiation, internal exposure from
inhalation of radon and thoron, and internal exposure from radionuclides in the body (NCRP
2009).
External exposure from space radiation is a consequence of bombardment of the earth by solar
particles and cosmic rays coming to the earth from space. In general, this radiation increases
with increasing altitude and latitude and contributes about the same fraction of the average
natural background radiation dose to an individual in Ohio as does terrestrial radiation.
Terrestrial radiation is a consequence of the radioactive decay of atoms (known as radionuclides)
that are present in the earth. Terrestrial radiation can be generally classified as being either alpha
(), beta () or gamma-ray () radiation. Alpha, beta and gamma-ray radiation are emitted in the
decay of radioactive nuclei. Alpha particles are energetic helium nuclei that are emitted in
radioactive decay. Beta particles are energetic electrons that are emitted in radioactive decay,
and gamma-rays are energetic photons that are emitted in radioactive decay. The classification
above of radiation as either alpha, beta, or gamma-ray radiation is not entirely precise, since
electrons can be emitted in radioactive decay processes that are not strictly classified as beta
particles (for example, conversion electrons); also energetic photons can be emitted in radiation
decay processes that are not strictly classified as gamma-rays (for example, x-rays).
Terrestrial radiation can be classified as primordial or cosmogenic. Primordial terrestrial
radiation is a consequence of the radioactive decay of radionuclides that were present when the
earth was formed. Cosmogenic terrestrial radiation is a consequence of the radioactive decay of
radionuclides that are produced by cosmic rays interacting with and transforming nuclei in the
earth’s atmosphere. These radionuclides are then incorporated into the matter of the earth.
Examples of primordial terrestrial radionuclides are uranium-238 (238U), uranium-235 (235U),
thorium-232 (232Th), and potassium-40 (40K). An example of a cosmogenic terrestrial
radionuclide is carbon-14 (14C). In general, cosmogenic terrestrial radionuclides contribute a
small fraction of the average terrestrial radiation dose to an individual in comparison to
primordial terrestrial radionuclides.
The distribution of space and terrestrial radiation doses for North America are shown in Figures
1 and 2, respectively.
5
6
Radon as Background Radiation
The 238U, 235U, and 232Th primordial radionuclides decay through radon-222 (222Rn), radon-219
(219Rn), and radon-220 (220Rn); respectively.1 These gaseous radionuclides can migrate from soil
into structures such as homes and lead to internal exposures, primarily from inhalation of their
short-lived radioactive progeny. The average radiation dose to a member of the U.S. population
from these gaseous radionuclides and their short-lived radioactive progeny is estimated to be
2.28 mSv/yr, with about 93 percent coming from 222Rn and its short-lived progeny and 7 percent
coming from 220Rn and its short-lived progeny (NCRP 2009). Because of its very short half-life
(3.96 s), the radiation dose from 219Rn and its progeny is very small.
According to the U.S. Environmental Protection Agency, the average indoor radon level is
estimated to be about 1.3 pCi/L while the average outdoor radon concentration is 0.4 pCi/L.
Figure 3 illustrates the distribution of indoor radon concentrations in the United States. This map
was developed using five factors to determine radon potentials: indoor radon measurements,
geology, aerial radioactivity, soil permeability, and foundation type. In Figure 3, indoor radon
concentrations are divided into three zones. Zone 1 contains counties with a predicted average
indoor screening level greater than 4 pCi/L, Zone 2 contains counties with a predicted average
indoor radon screening level between 2 and 4 pCi/L, and Zone 3 contains counties with a
predicted average indoor radon screening level less than 2 pCi/L. For example, central Ohio and
parts of western Pennsylvania are predominantly in Zone 1 (see Figure 3). Since radon (i.e.,
222
Rn) is a progeny of uranium, high concentrations of radon at the surface tend to be associated
with some rocks that have intruded into the Earth’s near-surface (some, but not all, igneous
intrusive and volcanic rock), shale rock, and soil containing glacial or shale debris. Most of Zone
1 occurs in the northern states and along regions where igneous rocks have recently intruded into
the Earth’s surface in the past hundreds of millions of years (e.g., Hawaii, and along the
Appalachian Mountains). In Ohio, counties with average radon concentrations greater than 4
pCi/L seem to be associated with the north-south trending Ohio Shale outcrop band, in limestone
glacial soils, and in some residual limestone soils (USGS 1993).
1 222
Rn is referred to as “radon,”
220
Rn is referred to as “thoron,” and
7
219
Rn is referred to as “actinon.”
Summary of Natural Background Radiation Doses
Figure 4 illustrates the contributions of the four categories of natural background radiation to the
total natural background radiation dose of 3.11 mSv/yr (NCRP 2009). Internal exposures from
radon and thoron account for about 73 percent of the total radiation dose from natural
background radiation, while external exposures from space radiation, internal exposures from
radionuclides in the body, and external exposures from terrestrial radiation account for 11
percent, 9 percent, and 7 percent of the total radiation dose, respectively.
8
Rocks and NORM
The Formation of Sedimentary Rocks Bearing Hydrocarbons and Radioactive Materials –
Appalachian Example
In the depths beneath the Appalachian surface, the upper part of Earth’s subsurface is divided
into two major rock layers called the sedimentary section and basement rocks. Basement rocks
are ancient (mostly greater than 1 billion years old) metamorphic and igneous rocks, while the
overlying sedimentary rocks are younger, formed when our region was periodically covered by
oceans and shallow seas. The depth of the ocean water and the climate at any given time
determined the type of sedimentary rock deposited. If the ocean water was warm and shallow,
coral reefs formed, while other times, the ocean water would recede slightly and sandy beaches
would form, creating layers of sandstone. At the mouth of rivers emptying sediments into the
ocean, deltas and swamps would form, while out in the deep water, fine grained clays and
organic material would be deposited. Each of the sediment layers (coral, sand, swamp muck, and
clays) eventually were buried and compacted as the overlying ocean depth and the regional
climate changed, forming a different rock layer (younger rock layers stacked on top of older
9
rocks). Under the pressure of burial, the coral was compacted into limestone, the organic rich
muck of the swamps became coal, the sand became sandstone, and the clays became shale.
These layers of different rock types form what geologists call the sedimentary section (see Figure
5). Organic compounds in the shale were converted, after millions of years of burial, to
hydrocarbons (oil and gas). A portion of the oil and gas moved (migrated) into overlying porous
sandstone and limestone where it was geologically “trapped” in certain geographic locations.
Until very recently, exploring and developing (drilling, extraction, and sometimes hydraulic
fracturing) geologic traps in sandstone and limestone with vertical drilling has been the mainstay
of the petroleum industry, and is often referred to as conventional petroleum development.
During the first century
and a half of the
petroleum industry, most
of the natural gas, and
some oil, remained
untapped in the shale
where the hydrocarbons
originated. Beginning in
the 21st century,
horizontal drilling and
hydraulic fracturing have
enabled the petroleum
industry to tap into the
hydrocarbons trapped in
the shale. The term “gas
shale” has become the
common term for
unconventional sources of
hydrocarbons extracted
from the shale rock. The
shale layers that are the
primary targets of
exploration in the
Midwest are the Marcellus Shale, formed approximately 385 million years ago, and the deeper
Utica Shale, formed approximately 475 million years ago.
10
Rocks and Radioactivity
With the exception of non- potassium bearing chemical precipitates (e.g., calcium carbonate,
anhydrite, halite, and kieserite) and
some pure mineral forms of igneous
rocks and minerals (e.g., quartz) and
metamorphic rocks (e.g., quartzite),
most of the rocks in the earth
contain some amount of 40K, the
uranium decay series (begins with
238
U) , actinium decay series (begins
with 235U, and/or the thorium decay
series (begins with 232Th). The
original source of radioactive
material in rocks (igneous,
metamorphic, and sedimentary) is
igneous and metamorphic rocks
(plutonic and volcanic) that existed
at the time the Earth was formed.
These igneous rocks were weathered
(by wind and water), disaggregated,
transported by streams and rivers,
and deposited in the form of inorganic sediments on the surface of the earth and in the ocean.
Sediments deposited in the ocean are called marine sediments, while those deposited on land and
in fresh water are called terrestrial or fluvial sediments, respectively. Sediments deposited close
to the ocean-land margins are called marginal marine deposits. Geologic strata that frequently
contain elevated NORM concentrations include: coal seams, phosphate-rich marine deposits,
some granitic rocks, some sandstones, some evaporate minerals (e.g., sylvite and potassium
phosphate), and marine black shale. The concentration of uranium in common rocks is shown in
Figure 6.
According to Schubert (2014),
the average NORM
concentrations in the Earth’s crust
(basement rocks below the
surface of the Earth) are as shown
in Figure 7.
11
Radioactivity in Shale
Geologically, shale is a laminated, indurated, fissile, sedimentary rock composed mostly of siltand clay-sized grains. A photograph of a Marcellus Shale outcrop is shown in Figure 8.
Hydrocarbon bearing shale’s were
predominantly formed by the
deposition of wind and water eroded
materials from exposed continental
crustal rock. The deep ocean
conditions that formed the Marcellus
Shale in the Appalachian oceanic
basin occurred approximately 375
million years ago (Devonian), and
for the Utica Shale the deep ocean
deposits formed approximately 475
million years ago (Ordovician). The
fine-grained material accumulated
40
on the sea floor. Radioactive materials ( K, uranium decay series, and thorium decay series
minerals) were likely introduced into the sediments from terrestrial, and possibly oceanic source
on the sea floor, while the fine-grained materials were still in an unconsolidated form lying on
the ocean floor. Changes in sea level, caused by movement of the continents, and/or tectonic
movement of the basement rocks (plutonic and volcanic) beneath the ocean caused calcium
carbonate inter-beds and other lithological layers between the fine-grained shale layers.
Eventually, long-cycle sea level changes caused the ocean deep to evolve into another non-shale
geologic environment (carbonate reef, beach, marginal marine, etc.), terminating the formation
of the shale layer. The geologic regime for the formation of shale is shown in Figure 9.
12
Shale is generally classified as gray shale or black shale, referring to the color of the shale. Gray
shale and black shale have the following characteristics (Babcock 2014):






Gray shale and black shale often occur together (see Figure 10)
Gray shale has a higher calcium
carbonate content
Black shale tends to have higher
organic carbon and iron sulfide
content
Gray shale tends to contain 40K
and members of the thorium
decay series
Black shale contains 40K, and
members of the thorium and
uranium decay series
Black shale is the primary
source rock for hydrocarbon
accumulation
Any radionuclide in crustal rocks can be expected to be present in shale, including the
primordial radioisotopes (238U, 235U, 232Th, and 40K) and decay products (progeny). The
radionuclides possibly present include: 40K, 232Th, 238U, 226Ra, 228Ra, and 222Rn. In summary,
according to Babcock (2014) shale can have high NORM values for the following reasons:

The radionuclides originally present in crustal source rocks, usually as impurities in their
mineral components, are present in shale.

Shale is the final repository of crustal weathering products, and can concentrate those
mineral components that cannot be readily broken down further

Shales have higher NORM values than most lithologies because 40K and 232Th
preferentially bond to clay minerals

In addition, organic-rich shale (“black shale”) has even higher NORM values because
238
U and 235U preferentially bond to organic matter.
NORM in Unconventional Oil and Gas Production
Shale can contain radionuclides in concentrations that are considerably greater than their
concentrations in other rock types, such as limestone, and can be classified as NORM. During
13
unconventional oil and gas production, NORM may appear from several different sources
(Lombardo 2014):



Gas – NORM (radon) may appear in
methane and during off-gassing.
Solids – NORM may appear in
horizontal drill cuttings – rock chips
created during the drilling process.
Figure 11 shows drill cuttings on a
vibrating mud screen.
Liquids – NORM may appear in
process and flowback water. In
addition, when NORM-containing
water is treated, the resulting sludge,
filter cakes, etc. almost always
concentrate the NORM as a solid.
The concern regarding hydraulic fracturing is that the radiation dose to individuals from
primordial terrestrial radiation will be increased as a consequence of bringing radionuclides that
are deep within the earth to the earth’s surface. However, the cuttings (from vertical and
horizontal drilling) do not have much greater concentrations of NORM than the same surface
rock and soil from the same geologic formations. Potential pathways for NORM to the surface
are shown in Figure 12.
There are two groups of people who
may be exposed to the radioactive
material derived from unconventional
oil and gas development; workers
and members of the public.
Exposures of workers are
characterized as occupational
exposures and exposures of members
of the public are characterized as
non-occupational exposures. Typical
exposure pathways for workers may
include direct radiation exposure to
contaminated drill cuttings, direct
radiation exposure to equipment
14
contaminated with radionuclides, and inhalation of dust containing radionuclides. Dust
inhalation could also occur when contaminated scale or sludge is cleaned from the inside
surfaces of equipment during well work-over operations Smith (1992). Direct contact with
contaminated scale and sludge could result in beta particle exposures to the skin. Potential
external exposures could occur when the concentration of radioactivity inside equipment is high
enough that gamma rays penetrate the equipment walls, and contaminated scale and sludge are
removed from the equipment, thereby eliminating the shielding factor provided by the equipment
walls (Smith 1992). Smith (1992) considered external exposure to be the pathway of greatest
concern for workers. Wastes from the treatment of production waters may also contain
concentrated radioactive material and, if so, controls would be required to limit radiation
exposure to workers handling this material as well as to ensure that this material is disposed of in
accordance with applicable regulatory requirements (DEC 2011).
For members of the public, potential exposure pathways could include radon inhalation, dust
inhalation from radioactive material blown offsite, external exposure to radioactive material
blown offsite, ingestion of radioactive material blown offsite, and radiation exposure through the
road spreading of brine, pit abandonment, and brine discharges to land. If flowback or produced
waters were discharged to surface or ground waters, exposures through these pathways could
also occur. However, EPA regulations strictly regulate the construction of hydraulic fracturing
wells and the handling of these waters, so these pathways are not likely to be significant.
TENORM in Unconventional Oil and Gas Production
Technically enhanced NORM, or TENORM is naturally occurring radioactive materials where
the concentration of NORM has been increased by human activity, or relocation, or processing of
NORM has increased potential radiation exposure to humans (Schubert 2014). TENORM
accumulates along with other drilling by-product
material as scale on pipes (see Figure 13) and
drilling equipment, and tends to accumulate in
the sludge that is concentrated from the drilling
process. Sludge is a concentration of particulate
matter that is a byproduct of water treatment and
filtration processes. For example, barium
extraction inadvertently concentrates radium in
filter cake sludge (drilling mud and very fine
particles ground up by the drilling process), as
do filter socks (fine mesh) that separate the
water from the particulate matter. Scale is
enhanced by acidity, temperature and pressure in
the well environment. Typically, when present in
15
NORM, TENORM contained in pipe and tank scale is included in the Group IIA elements
(barium, strontium, calcium, and radium).
Argonne National Laboratory recently evaluated the potential radiation doses from waste streams
containing TENORM in North Dakota (Harto et al. 2014). The waste streams included the scale
accumulated within pipe and other oilfield equipment, sludge accumulated in produced water
storage tanks and vessels, filter cake from filtration of water, disposable filter socks, and some
synthetic fracturing proppants that have been found to contain low levels of TENORM. For
workers, the exposure scenarios evaluated included mixing of hydraulic fracturing fluid,
produced water filtration, pipe cleaning, storage tank cleaning, equipment cleaning at a gas
processing plant, and sludge treatment. The results in Harto et al. (2014) suggest that it may be
important to monitor and limit the duration of exposure for workers involved in pipe and storage
tank cleaning activities and that the use of proper Personal Protective Equipment (PPE) is
important to protect workers with regular exposure to TENORM.
For members of the public, the exposure scenarios evaluated were based on improper waste
disposal, and included a child playing with a used filter sock, a load of filter socks being
disposed of in an urban dumpster, and a child playing in a pile of spilled synthetic proppants.
While the results in Harto et al. (2014) suggest that the risks to the public are likely relatively
low from short-term exposure to waste that is improperly disposed of, they are not representative
of all possible exposures, and Harto et al. (2014) states that extra care should be taken to ensure
that such exposures do not occur.
Operational Framework for Handling NORM and TENORM
The safe handling and disposal of NORM and TENORM begins on site, with the classification
and appropriate handling of drilling waste. As discussed in Gannon and Lopez (2014), NORM
management programs should be implemented that include basic radiation safety practices,
reduction of occupational and public exposures, reduction of environmental liability, and
reduction of costs. As illustrated in Figure 14 the elements of a successful NORM management
could include:






Detection of NORM
Establishing Action Limits
Contamination control procedures
Control of NORM-contaminated waste
Control of NORM-contaminated equipment
Development of standard operating procedures to cover potential contingencies.
16
Figure 14. NORM management framework (modified from Gannon and Lopez 2014).
Especially important is the protection of on-site workers, which can be achieved through worker
training and awareness, a hazard identification program, appropriate radiological controls, and
through the use of personal protective equipment.
A more general view of the disposal process from a regulatory perspective is shown in Figure 15
for the overarching operational lifecycle framework for NORM and TENORM handling and
disposal.
17
Figure 15. The overarching decision process for handling NORM and TENORM on and off the drilling
site (personal communication, Paul Ziemkiewicz, West Virginia University). (TCLP is the toxicity
characteristic leaching procedure (USEPA Publication SW 846). RCRA is the Resource Conservation and Recovery
Act of 1976. Subtitle B specifies the authorities of the administrator of the Office of Solid Waste. Subtitle C
specifies the “cradle to grave requirements” for solid waste disposal under RCRA. Subtitle D specifies procedures
for handling non-hazardous solid waste. NPDES is the National Pollutant Discharge Elimination System (water
permitting) as authorized by Section 402 of the Clean Water Act.)
Conclusions
Naturally occurring radioactive material is ubiquitous in subsurface rocks that are also
sometimes exposed as outcrops at the Earth’s surface. Like background solar and cosmic
radiation, they are a normal component of the radiation exposure on the Earth’s surface.
Radioactive minerals tend to concentrate in shale. Prior to hydraulic fracturing for oil and gas
production in shale, there was little concern about the relatively small quantities of shale rock
waste brought to the surface by conventional, vertical, oil and gas production in porous
sandstone and limestone producing zones. However, oil and gas production in a typical
horizontal well can yield several hundred cubic yards of solid waste from a single hole, and some
of this waste contains radioactive material that must be disposed of in RCRA Subtitle C landfills.
In order to separate waste containing radioactive material from uncontaminated material, special
procedures have been developed to handle solid (drilling chips) and liquid waste (sludge, and
flowback water) on drill sites. These procedures involve the identification of the waste according
to accepted standards and following the appropriate handling options (treatment, stabilization,
dilution, and transportation).
Although practices and procedures are in place at most drilling sites to ensure safe handling and
disposal of NORM and TENORM, the development of automated methods for on-site
classification and packaging of NORM contaminated waste could save time and money, and help
to ensure safe handling procedures. Research that better identifies the mineral constituents of
18
shale that are most likely to be associated with radioactive elements could provide an
improvement in predicting zones within a lateral drill hole that are likely to yield NORM
materials. In addition, the development of a process to separate and concentrate radioelements
from shale drilling waste would help to decrease the total amount of waste that requires Subtitle
C disposal.
Acknowledgments
NORM workshop presenters: Loren Babcock, The Ohio State University, Columbus, OH;
Tarunjit Butalia, The Ohio State University, Columbus, OH; Prabir Dutta, The Ohio State
University, Columbus, OH; John Frazier, consultant, Knoxville, TN; Mark Gannon, AMEC
Environment & Infrastructure, (Carnegie, PA); Mike Hall, Clean Harbors Environmental
Services, (Ogden, UT); Dennis Leeke, Pace Analytical, (Greensburg, PA); Andy Lombardo,
Perma-Fix Environmental Services, Beaver, PA; Alex Lopez, AMEC Environment &
Infrastructure, (Carnegie, PA); Mark Moody, Battelle, Columbus, OH; Holly Pearen,
Environmental Defense Fund, Boulder, CO; Jeff Schubert, Paul C. Rizzo Associates, Pittsburgh,
PA; Bill Thomas, Integrated Environmental Management, Findlay, OH; Elisabeth Widom,
Miami University, Oxford, OH; Paul Ziemkiewicz, West Virginia University, Morgantown, WV
NORM Working Group: Nick Basta, The Ohio State University, Columbus, OH; Mike Bisesi,
The Ohio State University, Columbus, OH; Thomas Blue, The Ohio State University,
Columbus, OH; Tarunjit Butalia, The Ohio State University, Columbus, OH; Raymond Cao, The
Ohio State University, Columbus, OH; Bob Chase, Marietta College, Marietta, OH; Roman
Lanno, The Ohio State University, Columbus, OH; John Lenhart, The Ohio State University,
Columbus, OH
Steve Maheras, Pacific Northwest National Laboratory, Columbus, OH; Dan Mueller,
Environmental Defense Fund, Austin, TX; Doug Patchen, West Virginia University,
Morgantown, WV; Doug Southgate, The Ohio State University, Columbus, OH; Tom Williams,
Environmentally Friendly Drilling, The Woodlands, TX; Bill Wolfe, The Ohio State University,
Columbus, OH
Special Thanks to Steve Maheras (PNNL), Thomas Blue (Ohio State), and Mike Bisesi (Ohio
State) for their extra efforts on early drafts of this paper.
19
References
American Heritage, 2011, Dictionary of the English Language, Fifth Edition, Houghton Mifflin Harcourt Publishing
Company.
Babcock LE. 2014. “The Geologic Nature of Shale.” Presented at NORM and TENORM: Occurrence,
Characterizing, Handling, and Disposal Workshop, May 12, 2014, Columbus, Ohio. Available at
http://serc.osu.edu/node/432.
DEC (New York State Department of Environmental Conservation). 2011. Revised Draft Supplemental Generic
Environmental Impact Statement on the Oil, Gas and Solution Mining Regulatory Program, Well Permit Issuance
for Horizontal Drilling and High-Volume Hydraulic Fracturing to Develop the Marcellus Shale and Other LowPermeability Gas Reservoirs. New York State Department of Environmental Conservation, Albany, New York.
Frazier JR. 2014. “Ionizing Radiation and Hazard Potential.” Presented at NORM and TENORM: Occurrence,
Characterizing, Handling, and Disposal Workshop, May 12, 2014, Columbus, Ohio. Available at
http://serc.osu.edu/node/432.
Gannon M and A Lopez. 2014. “Approaches with Recycle, Treatment, and Disposal of Flowback and Produced
Water and the ABCs of Managing NORM in the Marcellus Shale Region.” Presented at NORM and TENORM:
Occurrence, Characterizing, Handling, and Disposal Workshop, May 12, 2014, Columbus, Ohio. Available at
http://serc.osu.edu/node/432.
Harto CB, KP Smith, S Kamboj, and JJ Quinn. 2014. Radiological Dose and Risk Assessment of Landfill Disposal
of Technologically Enhanced Naturally Occurring Radioactive Materials (TENORM) In North Dakota. Report No.
ANL/EVS-14/13.
Lombardo A. 2014. “NORM and Unconventional Oil and Gas Production.” Presented at NORM and TENORM:
Occurrence, Characterizing, Handling, and Disposal Workshop, May 12, 2014, Columbus, Ohio. Available at
http://serc.osu.edu/node/432.
Moody M. 2014. “Basics of Drilling, Coring, and On-Site Disposal of Solids and Fluids.” Presented at NORM and
TENORM: Occurrence, Characterizing, Handling, and Disposal Workshop, May 12, 2014, Columbus, Ohio.
Available at http://serc.osu.edu/node/432.
NCRP (National Council on Radiation Protection and Measurements). 2009. Ionizing Radiation Exposure of the
Population of the United States. NCRP Report No. 160. National Council on Radiation Protection and
Measurements, Washington, D.C.
OEPA (Ohio Environmental Protection Agency). 2015. Marcellus and Utica Shale Regions in Ohio. Available at
http://epa.ohio.gov/MarcellusandUticaShale.aspx.
Schubert J. 2014. “NORM and TENORM Related to Geological Deposits and the Oil & Gas Industry.” Presented at
NORM and TENORM: Occurrence, Characterizing, Handling, and Disposal Workshop, May 12, 2014, Columbus,
Ohio. Available at http://serc.osu.edu/node/432.
Smith KP. 1992. An Overview of Naturally Occurring Radioactive Materials (NORM) in the Petroleum Industry.
Report No. ANL/EAIS-7. Argonne National Laboratory, Argonne, Illinois.
UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation). 2001. Report of the United
Nations Scientific Committee on the Effects of Atomic Radiation to the General Assembly. New York, New York.
USGS (U.S. Geological Survey). 1993. Geologic Radon Potential of EPA Region 5. Open File Report 93-292-E.
USGS (U.S. Geological Survey). 1997. Radioactive Elements in Coal and Fly Ash: Abundance, Forms, and
Environmental Significance. U.S. Geological Survey Fact Sheet FS-163-97.
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APPENDIX
Basics of Radioactivity
Steven Maheras, PNNL, [email protected]
Jeff Daniels, OSU, [email protected]
I.
Radiation
Radiation is energy in transit, either as particles or electromagnetic waves, and radioactivity is
the characteristic of some materials that emit radiation. Radioactive materials emit radiation, and
are often called radionuclides.
In the most fundamental definition, radiation is the term that describes the transmission of
energy through time and space, without the necessity of a physical medium to support the wave.
The different types of radiation are shown in Figure A1. A wave can propagate (move) through a
vacuum (e.g., outer space). Radiation may be in the form of waves (e.g., electromagnetic),
subatomic particles (e.g., neutrons, electrons), or subatomic energy packets that have wave and
particle characteristics (e.g., light, gamma rays, x-rays). Each type of radiation spreads out
(radiates) from a source, and the intensity of the radiation diminishes away from the source.
Figure A1. The electromagnetic spectrum and ionization
(http://www.arpansa.gov.au/radiationprotection/basics/ion_nonion.cfm).
21
Ionizing radiation is radiation that has enough energy to ionize atoms and change the structure
and nature of atoms. We usually think of gamma-rays, neutrons, and x-raysas ionizing radiation.
Radiation interacts with matter by imparting some, or all, of its energy in the matter that it hits.
Charged particles (e.g., alpha and beta particles) ionize or excite the atoms in matter, while
gamma rays and x-rays interact primarily with electrons. Ionization is the process wherein the
radiation interacts with matter and deposits some, or all, of its energy in atoms (or molecules) by
dislodging one or more electrons from the atom or molecule. After ionization, the atom is
ionized, and the atom is deficient by one or more electrons. If the atom is part of a molecule, then
ionization may lead to molecular dissociation (breaking) and subsequent recombination.
Radionuclides lose energy when they emit radiation, and they are said to decay with each
emission of radiation. At some point, the energy loss of the atom of a radionuclide reaches a
point whereby the original atom loses an alpha particle (a helium nucleus), gamma photon, or
beta particle (an energetic electron) and becomes a new atom with a lower energy level: The
original atom is called the parent atom, and the new atom is called the progeny atom. Figure 2(a)
illustrates the basics principle of radioactive decay.
Figure A2. Fundamental elements of radioactive decay: a) generalized decay and particle emission, b)
radioactive decay of 238U to 234Th.
The type of radioactive decay depends upon the original radionuclide, and decay mode may
result in emitting a gamma ray, a neutron, a beta particle, or an alpha particle. The radioactive
decay of 238U to 234Th is illustrated in Figure 2(b). The amount of time it takes for a parent
radionuclide to decay to a progeny radionuclide is called the half-life of the radionuclide. The
range of half-lives for radionuclides varies from very short (e.g., 160 sec for 214Po) to very long
(e.g., 4.5 billion years for 238U).
Primordial terrestrial radiation is mainly a consequence of the radioactive decay of radionuclides
in three naturally occurring decay series. These decay series are known as the uranium series,
the actinium series, and the thorium series. These series begin with 238U, 235U, and 232Th
respectively. A schematic for the uranium and thorium decay series and associated half-lives is
shown in Figure A3.
22
Figure A3. Uranium and Thorium Decay Series (Gannon, Lopez, 2014).
Here, the symbol U or Th represents the element Uranium or Thorium and the number following
the element symbol is the number of nucleons (protons and neutrons) in the nucleus of the atom.
The nuclei that begin the three naturally occurring decay series are the longest lived
radionuclides in their respective series. They have half-lives (the time that it takes for the
concentration of a specific radionuclide to decrease by a factor of ½, assuming there is no
migration of the radionuclides) on the order of the age of the earth. The three series end in stable
isotopes of lead, 206Pb, 207Pb, and 208Pb for the Uranium, Actinium and Thorium series
respectively. The radionuclides in the series decay by alpha, beta, and gamma-ray emission.
The rate of decay (number of decays per unit time) of each of the nuclei in the decay series
would be equal to the rate of decay (activity) of the radionuclide beginning the series (a
phenomenon known as secular equilibrium), if there were not migration of the radionuclides in
the earth.
23
II.
Measures of Radioactivity
Radioactivity is measured in terms of the number of radioactive particles or photons emitted by a
material and the energy of the particles or photons. The quantity, or number, of radioactive
particles or photons emitted by a radioactive material is called its activity, and the non-SI unit of
measure for activity is often expressed in terms of the curie (Ci), where 1 Ci = 3.7  1010
decays/s, which is approximately the activity of 1 gram of 226Ra. The SI unit is the becquerel
(Bq), which is 1 decay per second (1 Ci = 3.7  1010 Bq). For radiation to be ionizing, it must
have an energy greater than about 34 electron volts (eV).
The curie is also commonly used as a measure of the amount, by mass, of a radioactive material.
For example, the mass of 1 curie of radium is 1.01 grams of radium. The lower the emission rate,
and higher atomic mass, radioactive elements require a much higher mass per curie of material.
For example, it takes about 9.1 × 106 grams of 232Th or about 2.9 × 106 grams of 238U to
comprise 1 curie of material. Hence, the activity per unit mass (specific activity) is much lower
for 232Th and 238U than for 226Ra.
A radiation dose is caused by exposure to radiation or radioactive material. An internal dose is
caused by radioactive materials that may enter the body by inhalation, ingestion, injection, or
dermal absorption. An external dose is caused by exposure to radiation emitted by radioactive
materials that are outside of the body. The total radiation dose is the sum of the internal and
external doses to a specific organ or tissue.
For internal doses, the radiation doses is calculated based on the intake of a radionuclide, which
may be calculated from an intake rate and duration of intake or calculated from a bioassay, and a
dose coefficient, which is provided by published data2 and is based on the radionuclide,
chemical and physical form, and the route of intake:
Dose = Intake  Dose coefficient
External doses are calculated from the external radiation dose rate from a radionuclide and the
duration of exposure:
Dose = Dose Rate  Exposure Duration
External dose rates can vary with time and location, and may also be reduced by shielding.
The unit of measure for radiation dose in non-SI units is called the rem, where the rem is defined
in terms of the energy deposited per unit mass of tissue (1 rem = 100 erg/g). The SI unit of
radiation dose is the Sievert (Sv), where 1 Sv = 1 joule/kg and 1 Sv = 100 rem. Both the rem and
2
Two commonly used compilations of dose coefficients are contained in: 1) ICRP (International Commission on
Radiological Protection). 2001. The ICRP Database of Dose Coefficients: Workers and Members of the Public.
Version 2.0.1. New York, New York: Elsevier, and 2) EPA (U.S. Environmental Protection Agency). 2002. Federal
Guidance Report 13, CD Supplement, Cancer Risk Coefficients for Environmental Exposure to Radionuclides, EPA.
EPA-402-C-99001, Rev. 1. Washington, D.C.: U.S. Environmental Protection Agency.
24
the Sv take into account the biological damage caused to an organ or tissue by the specific type
of radiation (e.g., , , or ) and the risk of developing cancer or a severe genetic effect in the
organ or tissue.
The average annual radiation dose from natural background radiation sources and medical
sources are shown in Figures 4 and 5, respectively.
Figure A4. Annual Radiation Dose from Natural Sources
Figure A5. Annual Radiation Dose from Medical Sources (NCRP, 2009).
25