National Analytical Management Program (NAMP)

U.S. Department of Energy Carlsbad Field Office

In Cooperation with our 

University Partners

Radiochemistry Webinars

Environmental/Bioassay Radiochemistry Series

Unconventional Drilling/Hydraulic Fracturing and 

Natural Radioactivity
Meet the Presenters... Michael K. Schultz, PhD

Dr. Schultz is an Associate Professor in the Department of Radiology at the University of Iowa, with 

secondary appointments in the Free Radical and Radiation Biology; Human Toxicology; and Medical 

Scientist Training Programs. Dr Schultz also co-directs the Radiochemistry Program in the Department 

of Chemistry. His research interests in environmental radioactivity focus on naturally occurring 

radioactive material (NORM) associated with liquid and solid waste resulting from unconventional 

drilling and hydraulic fracturing. This year, Dr. Schultz has been invited to speak on this topic at the 

American Chemical Society National Meeting, the National Environmental Monitoring Conference, 

and ASTM International. A recent article (Nelson et al., Env Sci Techn Let, March 11, 2014) was 

selected for an ACS Editor’s Choice Award and the article, first authored by PhD graduate student and 

Presidential Fellow Andrew Nelson, is featured on the cover of the journal. Funded by the University 

of Iowa’s Center for Health Effects of Environmental Contaminants, Dr. Schultz's laboratory (with collaborator Tori Forbes, 

Department of Chemistry) has begun field studies on the environmental geochemical behavior of NORM in natural surface 

water systems impacted by unconventional drilling and hydraulic fracturing operations and waste treatment facilities. Mike 

earned his PhD in Oceanography at Florida State University, studying the environmental radiochemistry of anthropogenic and 

natural radionuclides in terrestrial and aquatic systems.

2

Andy Nelson, MS

Andy Nelson earned a B.A. in biochemistry from the University of Colorado in 2009 and an M.S. in 

environmental engineering from the Colorado School of Mines in 2010. As a research assistant in the 

Department of Molecular, Cellular, and Developmental Biology (MCDB) at the University of Colorado, 

Mr. Nelson studied free radical signaling mechanisms relevant in aging and tumor progression. In 2012, 

Andy was awarded the University of Iowa Presidential Graduate Fellowship to pursue a PhD in the 

Interdisciplinary Human Toxicology Program. He is currently a doctoral candidate under the 

mentorship of Dr. Schultz, with whom he studies radioactivity associated with unconventional drilling 

(hydraulic fracturing and horizontal drilling) of shale gas. Much of Mr. Nelson’s work to date has 

focused on developing methods that are suitable for monitoring levels of naturally occurring radioactive 

materials (NORM) present in wastes generated by unconventional natural gas exploration. Andy’s 

research has helped develop partitioning models that will be used in the development of sound waste 

management strategies for solid and liquid wastes generated by unconventional drilling. 
Radioactivity and Unconventional 

Drilling

Michael K. Schultz, PhD 

Andrew W. Nelson, MS

National Analytical Management Program (NAMP)

U.S. Department of Energy Carlsbad Field Office

TRAINING AND EDUCATION SUBCOMMITTEE
Disclaimer

Certain products and manufacturers are 

mentioned during this presentation for the 

purpose of fostering understanding. 

Reference to these commercial products and 

manufacturers in this presentation does not 

constitute recommendation or endorsement of the 

products.

4
5

Radiochemistry

Unconventional 

Drilling

Hydraulic

Fracturing
Outline

• Background on “fracking”?

– Why, Where, What and How

• Source of radioactivity

• Geochemical considerations

• Methods to detect NORM in flowback

• Considerations for:

– Liquid waste

– Solid waste

• Future research needs

6
Increasing Global Energy Demand

7

http://www.eia.gov
Unconventional Drilling Rapidly Expanding in U.S.

8

http://www.eia.gov
Major U.S. Natural Gas Plays

9

http://www.eia.gov
Global Shale Formations

10

http://www.eia.gov
What is Fracking?

11

“Fracking” = 

Hydraulic Fracturing ≈

Unconventional 

Drilling
5 Major Stages of Hydraulic Fracturing

12

http://www2.epa.gov/hfstudy/hydraulic-fracturing-water-cycle
Stage 1: Water Acquisition

• Water Usage

– Up to 55,000 m3(15 million 

gallons) per well

• Concern

– Straining water resources

• Arid states concerned

• Growing concern elsewhere

– Unknown contribution to 

radioactivity

• Recycling fluids?

13
Stage 2: Chemical Mixing

14

• Caustics and toxics

–Hydrochloric acid

–Proprietary chemicals

–Antimicrobials

–Unknown interactions with NORM

• Sand

–Crystalline silica

–OSHA hazard alert

–Mined in IA, WI

https://www.osha.gov/dts/hazardalerts/hydraulic_frac_hazard_alert.html
Stage 3: Well Injection

15

https://www.osha.gov/dts/hazardalerts/hydraulic_frac_hazard_alert.html
Radioactive Solid Waste

16

• Bit Cuttings

– 250,000 kg/well

– Trucks turned away 

from landfills

– Radiation alarms set 

off

https://www.rigzone.com/training/insight.asp?insight_id=

294&c_id=24

http://www.post-gazette.com/local/marcellusshale/2013/08/22/Marcellus-Shale-waste-trips-moreradioactivity-alarms-than-other-products-left-at-landfills/stories/201308220367
Stage 4: Flowback/Produced Water

17

Thousands of cubic meters (millions 

of gallons) produced fluids per well
Radioactive Produced Fluids

18

• Documented High 

Levels of Ra

> 670 Bq/L 226Ra

(18,000 pCi/L) 

> 95 Bq/L 228Ra

(2,500 pCi/L)
Stage 5: Disposal/Treatment of Waste

19

• Solids (250000 kg/well)

– Municipal landfills

• Radiation alarms

– Hazardous waste landfills

• Fluids 

– POTWs

– Industrial treatment

facilities

– Deep surface injection

– Recycling

– Transportation

considerations

• Trucking

• Barges?
Where does the radioactivity come from?

20

1. Radioactive Tracers

– Most common are gamma emitters

•

46Sc, 140La, 56Mn, 24Na, 124Sb, 192Ir, 99Tcm

, 

131I, 110Agm

, 

41Ar, 133Xe

– Measure flow rates & inter well connections

– Short half-lives (hours to days)

2. Naturally Occurring Radioactive Materials

– Present in the formation

•

238U (uranium) series

•

232Th (thorium) series

•

235U (actinium) series

– Long half-lives, decay products, differing chemistries

http://www-pub.iaea.org/MTCD/publications/PDF/Pub1171_web.pdf
Marine Black Shales

21

http://pubs.usgs.gov/pp/0356c/report.pdf

http://written-in-stone-seen-through-mylens.blogspot.com/2011/01/lacecrab.html

• Ancient marine 

environments

• High organic matter 

• High associated U levels
General Shale Geochemical Characteristics

22

• Reducing environment 

(anoxic)

• Microbial sulfate reduction

– Low sulfate concentrations

• High salt

–Evaporite

– Unclear where all the salt 

from Marcellus originates
General Chemistry of Uranium Series

23

http://metadata.berkeley.edu/nuclear-forensics/Decay%20Chains.html

• U redox sensitive (+6 soluble, +4 immobile)

• Pa particle reactive

• Th particle reactive

• Ra soluble in low-sulfate (SO4

2-

) brine

• Rn short-lived gas

• Po isotopes short-lived, redox sensitive, 

particle reactive

• Bi isotopes short-lived, supported by Pb 

isotopes

• Pb isotopes short-lived (exception 210Pb, 

which can accumulate in brine)
Case Study — Marcellus Shale

• One of the largest natural gas 

plays in the U.S.

• Underlies multiple states

• Regulation differs state to state

– NY “fracking’ moratorium

– OH, WV, PA allow

24

http://www.marcellus.psu.edu/

http://www.eia.gov/todayinenergy/detail.cfm?id=14091
NORM in the Marcellus Shale

25

http://www.eia.gov/todayinenergy/detail.cfm?id=14091

• Marine Black Shale

• Devonian Age 

– 350-400 million yrs old

• Radioactive decay 

products assumed in 

secular equilibrium
Lessons from NORM Analysis of Marcellus Flowback

26
Matrix

27

Ba:Ra ≈ 109

Analyte Concentration (mg/L)

Chloride 146,667

Strontium 36,333

Sodium 29,333

Calcium 13,000

Barium 9,000

Magnesium 853

Manganese 3

Iron 43

Total Solids 277,666

Suspended Solids 783
Scheme for Analysis

Gamma Emitters: 

228Ac, 226Ra, 224Ra, 

Pb and Bi isotopes, 

235U,

208Tl, 234Th

Special Case:

226Ra, 222Rn

Alpha Emitters 

(excluding Ra): 

Po Isotopes, 

U isotopes, 228Th, 

230Th, 232Th

28

Liquid 

Scintillation

Alpha Spec

HPGe 

Gamma Spec

Rad7
29

BaSO4 MnO2

610 Bq/L670 Bq/L

Wet Chemical Methods 

Not Effective
Analysis of Alpha Emitters

30

• Isotope dilution alpha spectrometry

– U

– Th

– Po

• Wet chemistry effective

– Pre-concentrations (ex: MnO2, FeOH3)

– Chromatography (ex: Eichrom® Resins)

– Microprecipitations (ex: CeOH3)
Simplifying the Matrix (MnO2

)

31

0.25 – 1L 

FBW

Precipitate

Chromatography

Complex

Digest Wash/Dissolve

Add Tracers

Add KMnO4
Method Summary

• Polonium

 Recoveries (81 ± 9 %) 

 Autodeposition slow

 Considered alternatives

• Uranium

 Recoveries (63 ± 8 %)

• Thorium

– Recoveries (85 ± 9 %)

32
Ingrowth of 210Pb and 210Po in Flowback

33

*H. Bateman, Proc. Cambridge Philos. Soc. 1910 (15) 423-
Uranium—Low Levels in Flowback

34

*[

226Ra= 670 Bq/L]
35

Ingrowing 228Th in Flowback
36

Partitioning Model

Th-234

U-238

Daughter 

recoil

U(IV)-234

Th-230 Ac-228 Th-228

Ra-224

Daughter

recoil Insoluble

Thorium Series

Uranium Series

Brine

Rock

Rock

Th-232

Pb-210

Fissure

U-234

Ra-226

Rn-222

Rn-222

Po-210 ?

Ra-228
Th-234

U-238

Daughter 

recoil

U(IV)-234

Th-230

Ra-226

Ac-228 Th-228

Ra-224

Daughter

recoil Insoluble

Thorium Series

Uranium Series

Brine

Rock

Rock

Th-232

Pb-210

Fissure

Rn-222

Po-210

Rn-222

U-234

Ra-228

The Big Picture

37
38

Importance of Partitioning

Decay Product Ingrowth in Flowback

*closed system
39

Ingrowth Occurs for Many Years
Special Considerations for Liquid Waste

• Enriched in Ra isotopes

– Can lead to Ra contamination

• Rn generators

– Inhalation hazards?

• Ra decay products ingrowth 

unavoidable

• Ra decay products have 

different chemistry

– Ra treatments (ex: sulfate 

precipitations)

• May not remove decay products

•

210Pb, 210Po, and 228Th of concern

• Difficult to detect

40
41

Liquid Waste in Marcellus Region

• Industrial Treatment

– Occurs in PA, WV, OH

– Ra decay products

– Occupational exposure?

– Surface Water 

Contamination?

• Underground Injection & 

Recycling Flowback

– Ra decay products

– Occupation exposure?

– Unclear fate of NORM after 

injection

onlinelibrary.wiley.com/doi/10.1002/wrcr.20096/pdf
Special Considerations with Solid Waste

• Bit cuttings coming from reduced 

environment to oxidizing surface

–Increase mobility of select 

radionuclides

• U4+  U6+

• Po speciation?

• Fe and Mn adsorptive surfaces may 

change

•

234U, 210Po, 232Th, 230Th, 228Th not 

detected by gamma-ray meters

–Note: 234U enriched by 

alpha-recoil, thus cannot assume

1:1 234U:238U activity

42

http://www.theguardian.com/enviro

nment/2011/jun/27/watershortages-threaten-renewable-energy
• Billions of kgs bit cuttings

• Interstate transfer 

• Most bit cuttings go to 

landfills

• Emerging reports of 

radioactivity alarms at 

landfills

– Unclear which isotopes

– Unclear what level of alpha 

emissions

• Concerns of radioactivity 

leaching

Solid Waste in Marcellus Region

43

http://www.triplepundit.com/2014/04/westvirginia-landfill-wastewater-shows-elevatedradioactivity-due-fracking-authorities-report/
Future Research Needs

On-going studies in the Schultz 

and Forbes Labs:

Other important questions:

• Bench studies on the behavior 

of NORM in bit cuttings from 

Marcellus Shale

• Field studies on the 

environmental fate and 

equilibrium status of Ra decay 

products

• What levels of 222Rn are 

released from landfills and 

wastewater treatment facilities 

accepting unconventional 

drilling waste?

• What is the potential/extent of 

bioaccumulation of NORM 

from unconventional drilling 

waste?
Thank you! Questions?

• State Hygienic Laboratory at UIowa

– Dr. Michael Wichman

– Marinea Mehrhoff

– Dustin May

• Schultz and Forbes Labs (UIowa)

– Dr. Michael K Schultz

– Dr. Tori Z Forbes

– Eric Eitrheim

– Andrew Knight

• EMS

– Robert Shannon

– Dr. Robert Litman

45
Questions and Answers
Question and Answer #1

• With the high level of salts in Marcellus shale, will K40 

NORM also have high level of radioactivity to consider? 

• Certainly 40K will be present in formations with high 

levels of K. We do not focus in the study of 40K as directly 

decays to stable isotopes. Consequently partitioning 

processes of 40K will not result in apparent increases of 

radioactivity like observed for the Ra decay series. Our 

gamma spectrometry results suggest that levels of 40K 

are 10 Bq/L, approximately 2 orders of magnitude lower 

than the levels of 226Ra (670 Bq/L)
Question and Answer #2

• The reference that was mentioned from USGS should be on a bibliography if not 

part of the handout. The links for some are accessed by clicking on them. There are 

some interesting follow on discussions well beyond this topic. How would we add 

these to the potential that might be studied by these researchers? One example is 

that when the flowback water is received at a POTW, the facility, which typically 

does not understand the chemistry for the radionuclides has several issues to deal 

with and these include:

1) Buildup of precipitates within the facility and occupational radiation exposure of 

personnel.

2) Disposal of liquid and solid wastes. The liquids need to meet Clean Water Act 

concentration guidelines and the solids that go to a landfill need to meet disposal 

(Form U) requirements. 

• The USGS manuscripts may be accessed at the following links: 

Rowan et al. 2011 http://pubs.usgs.gov/sir/2011/5135/

Swanson 1961 http://pubs.er.usgs.gov/publication/pp356C

We agree there are many potential questions to be addressed about occupational 

exposures. We cannot comment on the policies regarding waste management of 

liquid and solid wastes; however, we would like to point out that solid and liquid 

wastes from the oil and natural gas industry (as well as NORM wastes) may be 

regulated differently from state to state.
Question and Answer #3

• There are a number of companies that are receiving 

permits to evaluate, handle and then authorize NORMs 

and TENORMS for disposal. Companies like Austin 

Masters Services from Pottsville, PA, state that they have 

methods to evaluate radioactivity in closed trucks and 

clear them for processing and disposal. In your 

professional opinion, do technologies exist to evaluate 

radionuclides in complex, enclosed wastes such as drill 

cuttings and produced water?

• We suspect that these wastes are monitored by the gamma 

emissions. To truly quantitate the levels of gamma 

emitters in these wastes, an assumption about the 

distribution of the radionuclides in the wastes (i.e., are the 

wastes sorbed to the inside surface of the truck or equally 

distributed) and the geometry (i.e. is the truck square or 

cylindrical) of the truck is required. 
Question and Answer #4

• How many tons of drill cuttings are generated for a single horizontal 

well? How much liquid waste is generated during this stage? Is the 

crystalline silica more hazardous once it is covered with chemicals used in 

hydraulic fracturing? Should we be concerned about hazards other than 

simple silicosis?Why are they concentrating on flow back when it appears 

that produced water and drill cuttings seem to be more problematic? 

• The number of kilograms (not sure which unit of ton you are referring to: 

metric? Short?) from each well will vary. Some estimates suggest on 

average 250,000 kg per well, though keep in mind this will depend on a 

number of factors including the length of the well, the width of the well, 

the properties of the formation(s), etc. Liquid wastes greatly vary from 

well to well, depending on a multitude of factors. We hesititate to give a 

firm number as these number are so variable. For more information on 

silicosis as it relates to hydraulic fracturing, please visit 

https://www.osha.gov/dts/hazardalerts/hydraulic_frac_hazard_alert.ht

ml. Crystalline silica is not our area of expertise, but keep in mind that 

without exposure, there is no health risk. Exposure to crystalline silica is 

mostly an inhalation hazard.
Question and Answer #5

• As a student of atmospheric science, I would like 

to know if you know of any work that has been 

done regarding radioactive materials in the 

atmosphere through natural gas? What questions 

would you want to see addressed in this area?

• Fallout of Pb-210/Po-210 by Rn-222 gas in the 

atmosphere is a well known phenomenon. It will 

be interesting to see what levels of Rn-222 are 

released during flaring of natural gas from shale 

reservoirs.
Question and Answer #6

• How does the incidence of radioactive materials in 

shale deposits compare to other kinds of 

excavations? 

• Shale deposits and other organic rich formations 

appear to have higher levels of U due to various 

enrichment processes. This is advantageous to 

natural gas/oil exploration by use of gamma-ray 

logs. Solid wastes from these organic rich 

formations may be enriched in NORM. There are 

many excavations from other types of formations, 

however, the incidence of NORM in these other 

formations is outside our realm of expertise. 
Question and Answer #7

• Do the folks that work in the industrial wastewater 

treatment facilities that receive flowback wastes 

have their personal dose monitored? 

• We cannot comment on whether personal dose 

meters are worn; however, we suspect chronic 

inhalation of Rn-222 and its alpha-emitting decay 

products will pose a greater exposure risk than 

gross gamma or beta exposures.
Question and Answer #8

• A very valuable point regarding 212Pb. It is controlled by 224Ra not 

228Ra. This issue is important to clarify so that misrepresentation does 

not occur. What is of direct interest to this issue: what are the ratios of 

224Ra to 228Ra in the brines? In drinking waters, on rare occasion, 224Ra 

can be substantially enriched by factors 2X, 3X, or even slightly more. 

• We found that levels of 228Ra (measured by 228Ac) were 76 Bq/L one week 

after receipt in the lab. Levels of 224Ra by direct measurement were 

complicated by interferences from Pb/Bi isotopes; however, the 224Ra 

decay product 212Pb was 2.4 Bq/L. Assuming 212Pb were in equilibrium 

with 224Ra (i.e., no disequilibrium introduced by 220Rn), this would suggest 

levels of 224Ra were significantly lower than those of 228Ra. Not knowing 

the exact date when the sample was extracted from the formation, it is 

difficult to time correct the ratios of 224Ra to 228Ra at the time of 

extraction. Thus, we cannot comment (particularly due to the short halflife of 224Ra), what the ratio was at the time of extraction. This is a topic 

that warrants further investigation as it could also potentially be used as a 

forensics tool (like the 228Ra/228Th ratios) to determine when fluids were 

released from a well.
Question and Answer #9

• The partitioning is dependent on the pH and red-ox 

potential of the fluid in the horizontal part of the 

drilling. How can you get an estimation about the 

conditions down there? sampling will change the 

parameters, or do you have sampling possibilities 

without change in pressure or temperature?

• You raise some great points. We did not collect this 

sample, so we are interpreting it with the information 

that we have available. Certainly more investigations 

are warranted to determine how pH, redox, 

temperatures, and pressures change over time and how 

this will affect the partitioning of NORM.
Question and Answer #10

• What are the observed activity concentration ranges in all of your samples 

and approximate distributions of values among all samples for:

- Ra-226

- Ra-228

- Pb-210

- Po-210

- Rn-222

• Levels of Ra-226 were approximately 670 Bq/L. For more information on 

this topic, please refer to the following article:

Nelson et al. “Matrix Complications in the Determination of Radium 

Levels in Hydraulic Fracturing Flowback Water from Marcellus 

Shale”Environmental Science & Technology Letters 2014 1 (3), 204-208

For Ra-228, please refer to comment 8.

For levels of Pb-210, Po-210, and Rn-222 we hesitate to report a single 

value as these are moving targets. Initially Po-210 and Pb-210 were below 

detection limits, but over time they steadily increase in the sample as 

predicted by the Bateman equation. Rn-222 can be removed from the 

sample, but it will grow-in at a rate related to its own half-life until all the 

226Ra has been removed or decayed away.
Question and Answer #11

• What kind of concentration factors of NORM are 

you seeing with recycling of fracking water? 

• We have not done any analyses of recycled flowback

water. This is certainly a topic we find very 

interesting and one that warrants further 

investigation.
Question and Answer #12

• How much does the chemistry of different shale 

formations affect the partitioning of the various 

NORMs? In other words, what kind of variations in 

fracking-associated NORM are you seeing in different 

plays? 

• We have only investigated the NORM/chemistry in the 

Marcellus Shale. It will be interesting to see whether the 

lessons we have learned from the Marcellus Shale 

generally apply to the partitioning of NORM in other 

formations. Note that different formations are 

hydraulically fractured with different blends of fluids 

that may alter the fate of NORM within the formation 

and alter which NORM emerge from depth.
Question and Answer #13

• Would land application of flowback water or drill 

cuttings be environmentally safe at some levels of 

NORM? 

• Limiting exposure to radioactive materials is a good 

idea. Note that different individuals will have 

different tolerances for radioactive exposures. The 

potential health risks of application of NORM on land 

will not only depend on the levels of NORM, 

environmental conditions, but also the characteristics 

of the population exposed. Determining whether 

NORM disposal on land is safe, extends beyond the 

science, and includes social, political, and population 

distribution considerations. 
Question and Answer #14

• I’m interested to know the loading conditions of the 

sample prior to the TRU/TEVA separation. Also, 

what are the valence states of Po and U from the 

load solution? If you can provide any specifics of 

the TRU/TEVA separation scheme I would 

appreciate it. I’m curious because I have not seen a 

TRU/TEVA tandem arrangement. 

• This is the topic of a forthcoming publication. We 

will share this information as soon as it is 

published.
Question and Answer #15

• I understand that Radium is soluble in low-sulfate brines, so it makes sense that 

(in the Marcellus Shale formation) flowback water will have a higher 

concentration of Ra-226 compared to bit cuttings, and the total activity in the 

flowback water will increase over time as the Ra-226 decay products grow in. My 

question is, why doesn’t the same increase in activity levels occur with bit 

cuttings? My understanding is that the bit cuttings are considered to be in secular 

equilibrium, and typically don’t contain nearly as much Ra-226 as the flowback, 

but since the bit cuttings contain the parent isotopes of Ra-226, wouldn’t the bit 

cuttings still exhibit some sort of increase in activity over time as Ra-226 and the 

subsequent decay products are produced?

• The increase in flowback is observed because decay products are not soluble. Thus 

there is a partitioning process that is followed by natural ingrowth over time. We 

have not yet completed analyses of bit cuttings. With bit cuttings we expect there 

will be radium adsorbed to the surface of the minerals as well as contained in the 

rocks. Presumably some of the radium will be contained with in the rocks. As 

radium in the rocks decays, its decay product radon would likely be trapped and 

unable to partition away from the original source of radium. Thus there would be 

no increase in radioactivity, because the maximum radioactivity would already be 

established due to the lack of partitioning within the rocks. We are certainly 

interested in investigating the behavior of adsorbed radionuclides on bit cuttings. 
Upcoming NAMP Radiochemistry 

Webinars 

• Introduction to the Fuel Cycle – June 26, 2014

• Front End: Uranium Mining, Milling, Enrichment and UO2 

Production – July 24, 2014

• Environmental and human contamination in the Front End of the 

Fuel Cycle for Uranium Mining and Milling – August 21, 2014 

 Visit the NAMP website at www.wipp.energy.gov/namp