NORM Contamination in
the Petroleum Industry
P.R. Gray, SPE, Peter Gray & Assocs.

Summary. Contamination of oil
and gas facilities with naturally occurring radioactive materials (NORM) is
widespread. Some contamination
may be sufficiently severe that maintenance and other personnel may be
exposed to hazardous concentrations. Contamination with radium is
common in oil-production facilities,
whereas contamination with radon
and radon decay products is more
prevalent in natural-gas production
and processing facilities. Although
largely unregulated until recently,
U.S. states, notably Louisiana and
Texas, have or are enacting legislation to control NORM contamination
in the petroleum industry.

Introduction
NORM contamination can be expected at
nearly every petroleum facility. Some of it
can be sufficiently severe that maintenance
and other personnel may be exposed to hazardous concentrations. In addition, the industry must comply with new regulations.
Mississippi and Louisiana have enacted
legislation to control NORM; Texas will
have regulations early in 1993; and other
states, as well as Canada, can be expected
to have similar regulations shortly.
Two general types of common NORM
contamination will be controlled by these
regulations.
1. Radium contamination of petroleum
production facilities-specifically of pipe
scale and sludge and scale in surface vessels.
In addition, produced water may be radioactive from radium dissolved in underground
water.
2. Radon contamination of natural-gas
production facilities. This incl~des contamination with the long-lived decay products of
radon. Facilities that remove ethane and propane from natural-gas facilities are especially susceptible to NORM contamination.
Naturally occurring radionuclides are
widespread in the environment. In many
geologic formations, radium, radon, and
other radioactive elements are associated
with oil and gas. When oil and gas are produced, traces of these radioactive elements
also are produced. When the formation
water contains traces of radium
(radium-226, a decay product of uranium,
and radium-228 from thorium), scale in the
production pipe can become radioactive,
sometimes containing several thousand
picocuries of radium per gram of scale. 1.2
The radioactivity results when radium
coprecipitates with barium and strontium
sulfates in the scale formation.
Radium also can contaminate scale and
sludges in surface equipment by similar
mechanisms, including carbonate precipitates and sulfate deposits. Produced water
may contain dissolved radium. This can lead
to contaminated sludges in waste pits and
radioactive water.

Copyright 1993 Society of Petroleum Engineers

12

Contamination of gas wells, pipelines, and
gas processing facilities results primarily
from radon produced with natural gas. 3-6

NORM Contamination
NORM contamination in the oil and gas industry commonly occurs as radioactive
scale, films, and sludges.
Radium-Contaminated Scale and Sludge.
Radioactive scale can contain uranium, thorium, radium, and associated decay products
from the production of oil and associated
brines contaminated with NORM. The
radioactivity in the scale in production pipe
originates mainly from radium, which coprecipitates with barium and strontium sulfate. Other isotopes in the uranium-238 and
thorium-232 decay series also may be present. Contaminated scale may contain up to
several hundred thousand picocuries of
radium per gram of scale.
Radioactive scale may be found in surface
processing and transport equipment and in
downhole tubing. For example, piping,
sludge pits, filters, brine disposal/injection
wells, and associated equipment may be contaminated with radium NORM. Also, soils
and equipment contaminated from well tubing workovers conducted to remove scaleboth at the wellsite and at remote pipe cleaning yards-may be contaminated with
NORM.
Films. Radioactive films, coatings, or plating can form from natural-gas production
or processing. Often invisible to the naked
eye, these films contain radon and its decay products, normally with no radon precursors (e.g., radium) associated with them.
Because of radon contamination in natural
gas, these radioactive films can be found at
gas wellheads; in transport piping, headers,
treater units, and pumps; and within naturalgas processing plants or other light-hydrocarbon facilities.
Sludge Contaminated With Decay Products of Radon. Radioactive sludges in pipelines, processing plants, natural-gas liquid
(NGL) storage tanks and delivery facilities,
pigging operations, and gas lines and other
filter assemblies can be contaminated with
January 1993 • JPT

 TABLE 1-RAOON CONCENTRATIONS
IN NATURAL GAS AT THE WELLHEAO'

Location Of Well
Borneo
Canada
Alberta
British Columbia
Ontario
Germany
The Netherlands
Nigeria
North Sea
U.S.
Colorado, New Mexico
Texas, Kansas,
Oklahoma
Texas Panhandle
Colorado
California

Radon
Concentration
(pCilL)

1 to 3
10 to
390 to
4 to
1 to
1 to
1 to
2 to

205
540
800
10
45
3
4

1 to 160
1 to 1,450
10 to 520
11 to 45
1 to 100

'From Radon Concentrations in Natural Gas at /he Weli,
U.N. Scientific Committee on the Effects 01 Atomic
Radiation; SourCes and Effects of Ionizing Radiation,
United Nations, New York City (1977).

TABLE 2-BOILING POINTS
AT 760-mm MERCURY

OF
Methane
Ethane
Radon
Propylene
Propane
Butane

Fig. 1-Radioactive decay of uranium-238.

radon in the natural gas. Sludges also may
be contaminated with several thousand
picocuries per gram of the long-lived radon
decay products (i.e., lead-21O, bismuth-21O,
and polonium-21O). These heavy-metal decay products may attach to dust particles and
aerosols to become part of the sludge.
Filter assemblies in gas lines remove the
radon decay products from the gas with
other particulate matter and can become very
radioactive.

History of NORM Contamination
Radium has been known as a trace contaminant of underground water for a long
time but wasn't reported to be a contaminant
of scale until the early 1980's, when the
problem was first reported in the North Sea.
Radon contamination of natural gas has been
known for nearly 100 years. 7 However, it
was only in 1971 that radon was found to
concentrate in the lighter natural-gas liquids
during processing and could present a serious health hazard to industry personnel, particularly maintenance employees.
Some radon was undoubtedly removed
with the NGL's before 1971. However,
deep extraction techniques developed to remove more ethane from the gas also extracted significantly greater concentrations of
radon. The problem was discovered when
the radon contamination in propylene became sufficiently high to interfere with liquid level sensors detecting slurry levels in
a polypropylene plant.
JPT • January 1993

The radioactive scale problem in the oil
and gas industry has been reported in the
literature. 1,2 With the notable exception of
a 1975 report by Gese1l 8 and a paper by
Gray 9 in 1990, NORM contamination of
gas facilities by radon and its decay products
has not beeh as extensively reported.

Radium and Radon
Radium-226 is the fifth decay product of
uranium-238, and radium-228 is the fourth
decay product ofthorium-232. Uranium and
thorium are present in most soils and rocks
in widely varied concentrations in the
Earth's crust throughout the world. Some
radium salts (e.g., radium chloride) are soluble in water, and underground water can dissolve the radium in the uranium and thorium
formations. The radium may stay dissolved
in the water as long as contact with sulfate
and carbonate formations is limited. The
radium-contaminated water may be produced with oil and gas.
Radon is a naturally occurring, highly mobile, chemically inert radioactive gas in the
uranium-238 decay series. Radon-222 is
produced by the radioactive decay of
radium-226. Because radium is widely distributed in the Earth's crust, radon also is
widely distributed. Recent reports of radoncontaminated buildings throughout the world
attest to the wide distribution of radon in the
environment. Radon is a noble gas, similar
to helium and argon, and it is extremely un-

-258.0
-124.0
-79.2

-53.9
-44.4
+31.1

reactive chemically. Once formed by the
radioactive decay of radium-226, radon is
free to migrate as a gas or dissolve in water
without being trapped or removed by chemical reaction. Migrating through rocks and
soil, radon is produced with natural gas at
the wellhead. Table 1 shows that radon contamination of natural gas is a worldwide
problem, and particularly high concentrations of radon are reported in the U.S. and
Canada.
When radon-contaminated produced gas
is processed to remove the NGL's, much of
the radon is removed also. Radon's boiling
(or condensing) point is intermediate between the boiling points of ethane and propane. Upon subsequent processing, radon
tends to accumulate further in the propylene
distillation stream. Table 2 shows the boiling points of radon, the lighter NGL's, and
propylene. As expected, radon usually is recovered more completely in plants with high
ethane recovery. The radon is concentrated
in the lighter NGL's and is detected relatively easily with radiation survey meters.
As long as it is contained and controlled
within vessels, equipment, and piping, radon
generally is not a health hazard to employees
and the public. Even if radon-contaminated
propane were released, the threat of fire or
asphyxiation would far outweigh the hazard
of a short-lived radiation exposure.
Although other radon isotopes exist [e.g.,
radon-220 (thoron)] from the decay of thor ium-232, the only radon isotope of concern
13

 TABLE 3-PRIORITY AREAS OF
CONCERN FOR HIGH RADON
AND RADON DECAY
PRODUCT CONTAMINATION
NGL facilities

De-ethanizers
Stills
Fractionators
Product condensers
Flash tanks
Pumps in liquid service
Piping in liquid service
NGL storage tanks
Truck terminals
Filter separators
Dessicants
Waste pits
Pipelines
Filters
Pig receivers
Machine shops
In-house
Contract

is the 3.8-day half-life radon-222. Radon220 and other radon isotopes have very short
half-lives and will have decayed before the
gas is produced at the wellhead. Because the
half-life of radon-222 is 3.8 days, 99% of
the radon will decay to its long-lived
lead-21O decay product in 25 days.

Radon Decay Products
Radon itself is not a particularly hazardous
material. Because it is chemically unreactive, it does not accumulate in the body. The
health hazards associated with radon exposure are from its decay products. These
long-lived radioactive materials present a
growing problem to the industry, especially
to personnel who may be exposed to contaminated surfaces, sludges, and other waste
materials. Fig. 1 shows each atom of radon222 eventually decays to an atom of lead210 and subsequently to bismuth-21O and
polonium-21O before decaying to stable
lead-206. The half-life oflead-21O (a solid
metal material) is 22 years. Therefore, the
concentrations of radioactive lead, bismuth,
and polonium will continue to increase in
pipelines, gasoline plants, tank cars, and
trucks for more than 100 years.
Contaminated facilities and waste-material
problems must be recognized and addressed.
The presence of the radioactive metals from
radon decay cannot be detected on the outside of contaminated equipment and vessels.
Unlike radon, the radiations that the decay
products emit are easily absorbed by the
walls of the equipment. If present in sufficiently high concentrations, radon can be detected externally to storage vessels, pumps,
etc. Radon has moderately energetic gamma
radiation in its decay that can be detected
with gamma survey meters.
If an alphalbeta probe is held close to contaminated internal surfaces and concentrations are sufficiently high, survey meters
may detect the presence of the radon decay
products. However, laboratory analyses are
14

usually required to determine concentrations
oflead, bismuth, and polonium accurately.
These radioactive materials are not a
health hazard unless they are ingested or inhaled into the body-e.g., during repair and
maintenance on the facility. If inhaled, the
dust and aerosols containing NORM can attach to the lung surfaces, where they emit
alpha radiation into the tissue of the lung lining. Studies of uranium miners indicate that
extended exposure to these radon decay
products pose an increased risk of lung
cancer. 10, 11

NORM in NGL Facilities
Although entire natural-gas and NGL systems may be contaminated with NORM,
some facilities will be contaminated to the
extent that they present significant decontamination and disposal problems. Gasoline
plants and other NGL facilities will be
among the most highly contaminated areas
in a system.
During processing in a gasoline plant, the
levels of external radiation from radon in
propane 1 ft from a liquids pump may be as
high as 25 milliroentgens (mR)/hr. Radiation levels up to 6 mR/hr have been detected
at outer surfaces of storage tanks containing
fresh propane. Sludges in gasoline plants are
often contaminated with several thousand
picocuries of lead-21O per gram.
Table 3 shows vessels and equipment in
NGL service that may be significantly contaminated with NORM. Although NORM
contamination will be general throughout an
NGL facility, the contamination usually will
be greatest in areas of high turbulence, such
as in pumps and valves.
When employees open equipment and
vessels, precautions must betaken to prevent
exposure to radioactive contamination. 12
Maintenance procedures should include the
use of respirators and good hygiene to prevent inhalation of radioactive dust. Grinding, if necessary, should be done wet to
minimize dust.
Occasionally, a plant or other facility that
has been processing light hydrocarbons, particularly ethane and propane, is taken out
of service and the facility sold or dismantled.
Any equipment with internal surface deposits of NORM must receive special consideration when scrapped, sold, transferred,
or otherwise disposed of, particularly when
the facility is being released for unrestricted
use. Analyses for lead-21O usually will be
required to verify the extent of contamination and to determine if special handling is
needed. Particular care must be used to prevent employee exposure to NORM contamination.
There are potential liabilities involved if
contaminated equipment, vessels, and other
parts of the facility are released or sold for
unrestricted use without first being cleaned
and tested to be essentially free of NORM
contamination according to state and federal
regulations.
Much of the material wastes from a facility contaminated with NORM must be

handled as low-level radioactive waste and
disposed of accordingly. Contaminated
wastes should be consolidated and separated
from noncontaminated waste to keep radioactive waste volumes as low as possible.
Consolidated contaminated wastes should be
stored in a controlled-access area. The area
should be surveyed with a radiation survey
meter and, if required, should be posted according to state and federal regulations.

Other NORM Contamination
Besides vessels and equipment in NGL service, other facilities susceptible to significant
contamination include pigging operations,
machine shops, and filter assemblies.
Pipeline sludges can obtain small
radium-226 concentrations together with a
few hundred to several thousand picocuries
of radon decay products per gram. These
sludges require the same handling as lowlevel radioactive wastes. The pig itself may
be contaminated. This may require handling
the pig with gloves and storing it in an area
with restricted personnel access.
Machine shops present a special NORM
situation. For example, pumps in NGL service may be among the most highly contaminated equipment in it plant. Occasionally,
these pumps may need to be checked for
leaking seals or impeller balance. NORM
contamination inside a pump is often chemically bonded to the pump structural metal
and cannot be easily removed without scraping and grinding. Because rebalancing is
usually done by grinding until balance is established, the grinding may generate significant quantities of radioactive dust that can
contaminate personnel as well as the shop
facility. This can pose a very serious problem if contract machine shops are used.
Although pipelines and equipment in drygas service may be only marginally contaminated, filter assemblies in dry-gas service
may be contaminated with very high concentrations of NORM and require special
handling to prevent inhalation of the radioactive dust and contamination of the environment during changing of the filters and
other required maintenance.
Radiation Surveys
NORM contamination is detected by radiation surveys with Geiger-Mueller or scintillation probes on a suitable survey meter.
The gamma radiation emitted by radium and
radon are sufficiently energetic that they are
detected relatively easily if present in high
concentrations. The radiations emitted by
the decay products of radon are not easily
detected. The raditions from lead-2IO (Iowenergy gammas), bismuth-21O (betas), and
polonium-21O (alphas) will not penetrate
vessel and equipment walls and are detected
only with low efficiency when a suitable
probe (e.g., an alpha pancake probe) is used
directly on the contaminated surface. Because these radon decay products are detected, at best, with low efficiency, any
reading on the survey meter above background indicates significant contamination.
January 1993 • JPT

 Samples should be taken and submitted to
a laboratory for analysis. The exempt concentration levels for these radionuclides are
very low, and contamination above the exempt concentrations is common. Because the
radiations are easily absorbed, areal surveys
of the ground and soil around petroleum facilities for radon-decay-product contamination are generally not meaningful and
samples must be taken for laboratory
analyses.
Radium and radon emit sufficiently energetic radiation to make their detection somewhat easier. The gamma rays will commonly penetrate structure walls, making external radiation surveys with Geiger-Mueller
or scintillation detectors meaningful. The
exempt concentrations in the Louisiana and
Mississippi regulations and in pending regulations in other states are so low, however,
that concentrations of radium and radon near
the exempt levels are very difficult to measure accurately. A well-trained technician is
required to make such surveys with confidence. Again laboratory analyses may be
needed to determine accurately the amount
of contamination. Such analyses are probably required when the facility or property
is being sold, abandoned, or otherwise released. Accurate records of contamination
will be required to prevent future litigation.

Disposal of NORM Wastes
The disposal of NORM-contaminated wastes
is a major problem with no completely satisfactory solution. The disposal of NORM
wastes is regulated by Louisiana and Mississippi and will be regulated in all other states
as their regulations become effective. Options are limited. For example, the NORM
wastes must be separated from non-NORM
wastes and cannot be disposed of by "ordinary" methods of waste disposal, such as
landfills. Disposal of contaminated wastes
with uncontaminated material in a landfill or
by other methods of disposal is not allowed
unless the contamination level is below exempt concentrations in state and federal
regulations. The few facilities licensed to accept NORM wastes are expensive to use and
require a complete paper trail.
Although individual states or groups of
states are obligated to have low-level radioactive waste repositories by 1993, these facilities may not accept NORM wastes from
the petroleum industry. This is the case in
Texas, for example, where the Texas Low
Level Radioactive Waste Repository is designed to accept radioactive wastes from
medical facilities, educational institutions,
and industrial non-NORM wastes. The cost
of disposal will be expensive-Texas estimates that the cost of storing radioactive
wastes in its low-level repository will be
about $1751ft 3 .
Currently, the most economical and practical method may be to store the NORM
wastes on the facility property in an area
with controlled access. The revised Louisiana regulations address the disposal problem and require a proposed disposal plan be
JPT • January 1993

submitted to the state within 90 days of the
NORM generation.
It sometimes may be possible to dilute the
wastes sufficiently with noncontaminated
material so that the NORM concentrations
are below exempt levels. For example,
moderately contaminated soil may be diluted
with noncontaminated soil or radiumcontaminated water may be diluted with
"clean" water. If sufficiently diluted, the
resulting wastes may possibly be disposed
of by ordinary methods.
Reinjection of radium-contaminated water
is a possible solution to the disposal of such
water. Injection of other NORM wastes
(e.g., contaminated scale) in a Type II injection well may be the best possible disposal
method for these wastes when allowed by
the regulations.
The high cost of disposing of NORM
wastes is opening new opportunities for
R&D in methods and techniques for reducing waste volumes. For example, production waste may be contaminated above
exempt levels with radium-226 and
radium-228. If the radium could be removed
from the water economically, the costs of
disposing of the contaminated water would
be reduced significantly. There are R&D ef-

"The high cost of
disposing of NORM
wastes is opening new
opportunities for R&D
in methods and
techniques for reducing
waste volumes."
forts in progress to do this, such as using
resins and membranes to absorb or separate
the radium from water and other corrosive
liquids. Similar efforts are being applied to
concentrate radium and lead-2l0 and its
radioactive daughters from organic and inorganic sludges. If successful and economical, this may be a solution to the disposal
of large volumes of NORM-contaminated
wastes.
Decontamination of facilities by sandblasting can generate large volumes of NORM
wastes. Novel methods of "sandblasting"
with materials that will minimize the solid
wastes are being explored. Reaming out
scale from production pipe can generate
large quantities of NORM wastes. Because
only a fraction of the scale, possibly as low
as 5 % to 10%, may be contaminated above
exempt concentrations, preliminary gamma
surveys of the pipe to locate NORM sites
can be used to guide reaming operations and
to reduce NORM-contaminated scale
wastes. Contaminated scale may be spotty
(i.e., not uniform within the pipe), so the
total joint should be surveyed on all sides.
External scale on the pipe also can be contaminated with radium, necessitating careful
handling to prevent ingestion or inhalation

of NORM dust and contamination of the environment.
As an alternative to reworking or cleaning
of contaminated production pipe, the pipe
can be left in place in the ground. It is not
required to pull the pipe and remove the contaminated scale.
The trend in U.S. state regulations is
toward more regulation and control of
NORM wastes. NORM disposal will undoubtedly become very expensive.

Regulations
Radium and radon in oil and gas operations
produce radioactive waste materials that
contaminate facilities and equipment, exposing employees to hazardous materials and
creating waste disposal problems. Such
wastes and facilities should be treated as
much as possible like other facilities and
equipment covered by the U.S. Atomic
Energy Act (e.g., soil contamination limits,
criteria for facilities and equipment released
for unrestricted use, and rules for proper
handling and disposal of contaminated materials).
Several state and federal agencies have
potential jurisdiction over NORM, but their
application to NORM is unclear. NORM
does not fall under the definition of source,
special nuclear, or by-product material as
currently defined in the Atomic Energy Act.
Therefore, NORM is not subject to the
Nuclear Regulatory Commission regulations. States have laws and regulations
governing the use, possession, handling, and
disposal of radioactive materials, but their
application to NORM is still unclear. Except
for Louisiana and Mississippi, no specific
state regulations for the control of NORM
contamination exist. Texas and several other
states are expected to have NORM regulations in 1993. Louisiana specifically exempts
the wholesale and retail distribution, possession, use, and transportation of oil and natural gas and NGL's from the regulations.
The exemption, however, does not apply to
contaminated facilities, such as pipelines,
gasoline plants, and other physical facilities.
The Louisiana and Mississippi and other
proposed state regulations are very specific
regarding disposal of contaminated wastes
and sale, abandonment, or release of facilities that may be contaminated. Companies
doing production pipe cleaning and workovers must be specifically licensed, as do
contractors supplying decontamination services. Louisiana has required radiation surveys of every petroleum facility in the state.
As proposed, the Texas regulations will not
require such extensive surveys. Texas will
require surveys only of specific licensed facilities.
To ensure compliance, companies must be
familiar with the regulations as they evolve.
Although only Louisiana and Mississippi
have regulations in effect, Texas, other
states, and Canada are expected to have
regulations soon for the control of NORM
in the petroleum industry. The U.S. Environmental Protection Agency (EPA) is also
15

 Author
Peter Gray Is a
consultant on NORM
contamination In
the petroleum Industry. He retired
In 1985 from Phillips Petroleum Co.
where he was the
principal investl·
gator in Phillips'
NORM control program. Gray holds BS and MS degrees
from Michigan Technological U. and a
PhD in nuclear chemistry from the U. of
California at Berkeley.

considering enacting NORM regulations on
the federal level.
Regulatory developments must be monitored as current knowledge of the NORM
issues evolves. Where possible, industry input should be directed to minimize an overregulation of NORM contamination in the
industry.

Suggested Program
for the Control of NORM
The following are suggestions for use in establishing a program for the control of
NORM contamination.
1. Determine whether there is a NORM
contamination problem.
2. Determine areas of potential NORM
exposure and contamination.
A. Make gamma radiation surveys of
facilities and equipment.
B. Make wipe tests on accessible interior surfaces of selected equipment and vessels, especially any in NGL service.
C. Obtain samples of sludges and scale
and analyze for radium and lead-21O.
D. Obtain samples of other waste materials, such as dessicants and filters.
E. Analyze produced water and waste
pond water for radium.
3. Establish programs to ensure personnel
safety, product quality, customer satisfaction, and protection of the environment.
A. Establish policy on periodic surveys,
inspection and maintenance procedures,
product controls, and record keeping.
B. Provide safety-manual material that
informs employees and details required
procedures, particularly for maintenance
personnel.
C. Recommend a management and audit system.
D. Develop plans and procedures for
the disposal of contaminated waste materials, equipment, and facilities.

16

E. Prepare a public relations release to
use if questioned by employees, customers,
the public, and the media.
4. Inform facility personnel of the possibility of NORM contamination.
5. Review governmental regulations to
ensure regulatory compliance.

Conclusions
1. NORM contamination can be expected
at nearly every petroleum facility.
2. The presence of NORM in oil and gas
production facilities, gas processing plants,
pipelines, and other petroleum equipment
and facilities is not, in general, a serious
technical problem.
3. The concentrations of NORM contamination and the energies of the radiation are
relatively low and do not usually present a
health hazard to the public or to most personnel in the industry. Some facilities may
be more highly contaminated, however, and
may be hazardous to maintenance personnel
in particular.
4. Radium contamination of pipe scale
can be a serious problem requiring special
procedures for the removal and disposal of
contaminated scale to prevent contamination
of personnel and the environment.
5. Produced water may be contaminated
with radium, requiring special procedures
for the protection of the environment.
6. Surface equipment and facilities at production sites also may be contaminated with
NORM, requiring special repair and maintenance procedures and the disposal of
NORM-contaminated wastes.
7. The buildup of long-lived radon decay
products (specifically lead-21O) in gas pipelines, gasoline plants, and refineries requires
that specific procedures be implemented for
inspection and maintenance personnel to ensure their safety when working on the internal parts of equipment and facilities where
radon may have been present.
8. A serious problem that must be addressed is the disposal of radioactive materials and equipment. Options available for
the disposal of NORM and NORM-contaminated wastes are limited.
9. Although only Louisiana and Mississippi have enacted regulations for the control
of NORM, Texas will have regulations early
in 1993, and other states and Canada can be
expected to enact similar legislation. The
U.S. EPA is considering enacting NORM
regulations on the federal level.
10. The industry must comply with the
regulations.
Although potentially hazardous to personnel and the environment, NORM contamination is controllable.

References
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10. Whittmore, A.S. and McMillan, A.: "Lung
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Miners: A Reappraisal," J. Nat!. Cancer Inst.
(1983) 71, 489-99.
II. Svec, J., Kunz, E., and Placek, V.: "Lung
Cancer in Uranium Miners and Long-Tenn
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12. Summerlin, J. Jr. and Prichard, H.M.:
"Radiological Health Implications of
Lead-21O and Polonium-21O Accumulations
in LPG Refineries," J. American Industrial
Hygiene Assn. (1985) 46, No.4, 202-05.

SI Metric Conversion Factors
curie x 3.7'
OF
ft
ft3
R

(OF - 32)/1.8

x 3.048'
x 2.831685
x 2.58

E+IO = Bq
= °C

E-01 = m
E-02 = m 3
E-04 = C/kg

*Conversion factor is exact.

Provenance
Original SPE manuscript, NORM Contamination in the Petroleum Industry, received for review Oct. 6, 1991. Revised
manuscript received Oct. 29, 1992. Paper
accepted for publication Jan. 15, 1992. Paper (SPE 22880) first presented at the 1991
SPE Annual Technical Conference and Exhibition held in Dallas, Oct. 6-9.

JPT

January 1993 • JPT