Page 1 of 44

DOE Review Release 09/15/2017 

Weldon Spring Plant – Site Description

ORAUT-TKBS-0028-2 Rev. 03

Effective Date: 09/12/2017

Supersedes: Revision 02

Subject Expert(s): David P. Harrison

Document Owner 

Approval: Signature on File

David P. Harrison, Document Owner

Approval Date: 09/11/2017

Concurrence: Signature on File

John M. Byrne, Objective 1 Manager

Concurrence Date: 09/11/2017

Concurrence: Signature on File

Scott R. Siebert, Objective 3 Manager

Concurrence Date: 09/11/2017

Concurrence: Vickie S. Short Signature on File for

Kate Kimpan, Project Director

Concurrence Date: 09/11/2017

Approval: Signature on File

Stuart L. Hinnefeld, Director, DCAS

Approval Date: 09/12/2017

FOR DOCUMENTS MARKED AS A TOTAL REWRITE, REVISION, OR PAGE CHANGE, REPLACE THE PRIOR 

REVISION AND DISCARD / DESTROY ALL COPIES OF THE PRIOR REVISION.

New Total Rewrite Revision Page Change
Document No. ORAUT-TKBS-0028-2 Revision No. 03 Effective Date: 09/12/2017 Page 2 of 44

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION 

NUMBER DESCRIPTION

06/24/2005 00 First approved issue. New technical basis document for the Weldon 

Spring Plant – Site Description. Incorporates formal internal and 

NIOSH review comments. Training is not required. Initiated by 

Robert Meyer.

05/21/2013 01 Revision to incorporate data that has been found since the initial draft 

was issued. Description of processed materials and throughputs 

were updated. No changes occurred as a result of formal internal 

review. Incorporates formal NIOSH review comments. Constitutes a 

total rewrite of the document. Training required: As determined by 

the Objective Manager. Initiated by David P. Harrison.

03/24/2017 02 Revision initiated to refer to Rev 02 of the Fernald internal dose 

technical basis document regarding recycled uranium contaminants 

and their mass concentrations. Includes editorial changes. No 

changes occurred as a result of formal internal review. Incorporates 

formal NIOSH review comments. Constitutes a total rewrite of the 

document. Training required: As determined by the Objective 

Manager. Initiated by David P. Harrison. 

09/12/2017 03 Revision initiated to correct wording in Section 2.4.1 regarding the 

year recycled uranium work began at the Weldon Spring Plant. 

Includes editorial changes. Updated references in the text and in the 

Reference Section. No sections were deleted. No changes were 

needed as a result of formal internal review. Incorporates formal 

NIOSH review comments. Training required: As determined by the 

Objective Manager. Initiated by David P. Harrison. 
Document No. ORAUT-TKBS-0028-2 Revision No. 03 Effective Date: 09/12/2017 Page 3 of 44

TABLE OF CONTENTS

SECTION TITLE PAGE

Acronyms and Abbreviations ............................................................................................................... 5

2.1 Introduction .............................................................................................................................. 7

2.1.1 Purpose........................................................................................................................ 8

2.1.2 Scope........................................................................................................................... 8

2.2 Site Location and Summary History ......................................................................................... 8

2.3 Site Acquisition and Development, 1954 to 1957 ................................................................... 10

2.4 Operational Period, 1957 to 1966........................................................................................... 11

2.4.1 Processed Materials ................................................................................................... 11

2.4.2 Plant Processes and Operations ................................................................................ 13

2.4.2.1 Uranium Concentrate Sampling ................................................................... 13

2.4.2.2 Uranium Trioxide Production........................................................................ 14

2.4.2.3 Uranium Tetrafluoride Production................................................................. 14

2.4.2.4 Uranium Tetrafluoride Conversion................................................................ 16

2.4.2.5 Products Manufacturing ............................................................................... 16

2.4.2.6 Thorium Processing ..................................................................................... 17

2.4.2.7 Analytical and Research Laboratories.......................................................... 17

2.4.2.8 Pilot Plants................................................................................................... 18

2.4.2.9 Raffinate Pits................................................................................................ 18

2.4.2.10 Weldon Spring Quarry.................................................................................. 19

2.4.3 Plant Operations and Radioactive Material of Concern Summary............................... 19

2.5 U.S. Department of Defense Control Period, 1967 to 1985 .................................................... 19

2.6 Remediation Period, 1985 to 2002......................................................................................... 24

2.7 Releases to the Outdoor Environment.................................................................................... 25

2.7.1 Airborne Emissions..................................................................................................... 25

2.7.2 Waterborne Emissions................................................................................................ 26

2.7.3 Accidents.................................................................................................................... 28

2.8 Health Protection Practices .................................................................................................... 28

2.8.1 Operational Period, 1957 to 1966 ............................................................................... 28

2.8.1.1 Badging........................................................................................................ 30

2.8.1.2 Radiological Exposure and Access Control.................................................. 30

2.8.2 U.S. Department of Defense Control of Chemical Plant, 1967 to 1985 ....................... 31

2.8.3 Remediation Period, 1985 to 2002 ............................................................................. 31

2.8.3.1 Badging........................................................................................................ 32

2.8.3.2 Radiological Exposure and Access Control.................................................. 32

2.9 Job Titles and Locations During Operational Period............................................................... 33

2.10 Attributions and Annotations .................................................................................................. 36

References ........................................................................................................................................ 37
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Glossary ............................................................................................................................................ 42

LIST OF TABLES

TABLE TITLE PAGE

2-1 Annual uranium and thorium mass receipts ........................................................................... 11

2-2 Thoron and progeny...............................................................................................................13

2-3 Chronological summary of thorium operations ....................................................................... 17

2-4 Description of WSP buildings and operations......................................................................... 20

2-5 History of radioactive effluent-generating activities................................................................. 25

2-6 Location and height of stacks at the WSP.............................................................................. 26

2-7 Estimated annual discharges to stacks .................................................................................. 26

2-8 Estimated annual discharges to raffinate pits ......................................................................... 27

2-9 Estimated annual discharges to sewer................................................................................... 28

2-10 Forms for reporting high urinary uranium results .................................................................... 29

2-11 Tolerated dose limits in 1955 ................................................................................................. 29

2-12 Guides for prescribing restricted work based on radiation exposure in 1965 .......................... 30

2-13 Partial list of job titles and locations during operational period................................................ 33

LIST OF FIGURES

FIGURE TITLE PAGE

2-1 Locations of WSP facilities ....................................................................................................... 9

2-2 WSP and WSRP site layout ................................................................................................... 10

2-3 Sampling plant flow diagram .................................................................................................. 14

2-4 Digestion, purification, and denitration.................................................................................... 15

2-5 Reduction and hydrofluorination process ............................................................................... 15

2-6 UF4 conversion to uranium metal............................................................................................ 16
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ACRONYMS AND ABBREVIATIONS 

ac acre

AEC U.S. Atomic Energy Commission

AWE Atomic Weapons Employer

BZA breathing-zone air

CEDE committed effective dose equivalent

CFR Code of Federal Regulations

Ci curie

cm centimeter

CSS Chemical Stabilization and Solidification (facility)

d day

DOD U.S. Department of Defense

DOE U.S. Department of Energy

DOL U.S. Department of Labor

DU depleted uranium

EDE effective dose equivalent

EEOICPA Energy Employees Occupational Illness Compensation Program Act of 2000

EPA U.S. Environmental Protection Agency

EU enriched uranium

ft foot

gal gallon

HEPA high-efficiency particulate air

hr hour

in. inch

kg kilogram

L liter

m meter

MCW Mallinckrodt Chemical Works

MeV megaelectron-volt, 1 million electron-volts

mg milligram

mi mile

mR milliroentgen

mrem millirem

mrep millirep

MT metric ton

nCi nanocuries

NIOSH National Institute for Occupational Safety and Health

NLO National Lead Company of Ohio

NPL National Priorities List

ns nanosecond
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NU natural uranium

ORAU Oak Ridge Associated Universities

pCi picocuries

RI/FS remedial investigation/feasibility study

RU recycled uranium

s second

SEC Special Exposure Cohort

SRDB Ref ID Site Research Database Reference Identification (number)

SWTP Site Water Treatment Plant

t ton

TBD technical basis document

TNT thorium nitrate tetrahydrate

TSA Temporary Storage Area

U.S.C. United States Code

wk week

WSP Weldon Spring Plant

WSQ Weldon Spring Quarry

WSRP Weldon Spring Raffinate Pits

WSSRAP Weldon Spring Site Remedial Action Project

yd yard

yr year

μs microsecond

°F degrees Fahrenheit

§ section or sections
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2.1 INTRODUCTION

Technical basis documents and site profile documents are not official determinations made by the 

National Institute for Occupational Safety and Health (NIOSH) but are rather general working 

documents that provide historical background information and guidance to assist in the preparation of 

dose reconstructions at particular Department of Energy (DOE) or Atomic Weapons Employer (AWE) 

facilities or categories of DOE or AWE facilities. They will be revised in the event additional relevant 

information is obtained about the affected DOE or AWE facility(ies). These documents may be used 

to assist NIOSH staff in the evaluation of Special Exposure Cohort (SEC) petitions and the completion 

of the individual work required for each dose reconstruction.

In this document the word “facility” is used to refer to an area, building, or group of buildings that 

served a specific purpose at a DOE or AWE facility. It does not mean nor should it be equated to an 

“AWE facility” or a “DOE facility.” The terms AWE and DOE facility are defined in sections 7384l(5) 

and (12) of the Energy Employees Occupational Illness Compensation Program Act of 2000 

(EEOICPA), respectively. An AWE facility means “a facility, owned by an atomic weapons employer, 

that is or was used to process or produce, for use by the United States, material that emitted radiation 

and was used in the production of an atomic weapon, excluding uranium mining or milling.” 42 U.S.C. 

§ 7384l(5). On the other hand, a DOE facility is defined as “any building, structure, or premise, 

including the grounds upon which such building, structure, or premise is located ... in which 

operations are, or have been, conducted by, or on behalf of, the [DOE] (except for buildings, 

structures, premises, grounds, or operations ... pertaining to the Naval Nuclear Propulsion Program);” 

and with regard to which DOE has or had a proprietary interest, or “entered into a contract with an 

entity to provide management and operation, management and integration, environmental 

remediation services, construction, or maintenance services.” 42 U.S.C. § 7384l(12). The Department 

of Energy (DOE) determines whether a site meets the statutory definition of an AWE facility and the 

Department of Labor (DOL) determines if a site is a DOE facility and, if it is, designates it as such.

Accordingly, a Part B claim for benefits must be based on an energy employee’s eligible employment 

and occupational radiation exposure at a DOE or AWE facility during the facility’s designated time 

period and location (i.e., covered employee). After DOL determines that a claim meets the eligibility 

requirements under EEOICPA, DOL transmits the claim to NIOSH for a dose reconstruction. 

EEOICPA provides, among other things, guidance on eligible employment and the types of radiation 

exposure to be included in an individual dose reconstruction. Under EEOICPA, eligible employment 

at a DOE facility includes individuals who are or were employed by DOE and its predecessor 

agencies, as well as their contractors and subcontractors at the facility. Unlike the abovementioned 

statutory provisions on DOE facility definitions that contain specific descriptions or exclusions on 

facility designation, the statutory provision governing types of exposure to be included in dose 

reconstructions for DOE covered employees only requires that such exposures be incurred in the 

performance of duty. As such, NIOSH broadly construes radiation exposures incurred in the 

performance of duty to include all radiation exposures received as a condition of employment at 

covered DOE facilities in its dose reconstructions for covered employees. For covered employees at 

DOE facilities, individual dose reconstructions may also include radiation exposures related to the 

Naval Nuclear Propulsion Program at DOE facilities, if applicable. No efforts are made to determine 

the eligibility of any fraction of total measured exposure for inclusion in dose reconstruction.

NIOSH does not consider the following types of exposure as those incurred in the performance of 

duty as a condition of employment at a DOE facility. Therefore these exposures are not included in 

dose reconstructions for covered employees (NIOSH 2010):

• Background radiation, including radiation from naturally occurring radon present in 

conventional structures

• Radiation from X-rays received in the diagnosis of injuries or illnesses or for therapeutic 

reasons
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2.1.1 Purpose

The purpose of this technical basis document (TBD) is to provide historical information on facilities, 

processes, operations, and their associated nuclear materials of potential concern for the Weldon 

Spring Plant (WSP), Weldon Spring Quarry (WSQ), and the Weldon Spring Raffinate Pits (WSRP). 

Historically, the WSP has also been called the Weldon Spring Site, Weldon Spring Chemical Plant, 

and the Weldon Spring Feed Materials Plant. The WSP is also known as the Chemical Plant, Main 

Plant, or Main Site. For convenience, WSP is used throughout the remainder of this document where 

it is unnecessary to distinguish between the plant, the quarry, and the raffinate pits. This document 

provides background information for the subsequent TBDs in which further technical details are 

developed to support dose reconstruction. WSP operations played an important role in U.S. 

development of nuclear power and nuclear weapons. Operations focused on processing uranium and 

thorium from feed stocks to metal and other intermediate products for use at other facilities.

2.1.2 Scope

Section 2.2 provides the location and general history of WSP, and Sections 2.3 and 2.4 discuss site 

acquisition and development from 1954 to 1957 and site operations from 1957 to 1966. Section 2.5 

covers 1967 to 1985 when the WSP was under the control of the U.S. Department of Defense (DOD), 

and Section 2.6 covers the DOE remediation period from 1985 to 2002. Section 2.7 discusses 

releases to the outdoor environment, and Section 2.8 discusses health protection at WSP during all 

periods. Section 2.9 provides supplemental information on job titles and locations during the 

operational period. Attributions and annotations, indicated by bracketed callouts and used to identify 

the source, justification, or clarification of the associated information, are presented in Section 2.10. 

2.2 SITE LOCATION AND SUMMARY HISTORY

The main area of the WSP is a 220-ac site about 2 mi southwest of the community of Weldon Spring, 

Missouri, at the junction of Missouri State Route 94 and U.S. Highway 40/61 (Figure 2-1). The site 

contained 44 buildings and support structures along with two small ponds and the remnants of a 

railroad system (WSP) and four raffinate pits (WSRP). An 8.7-ac limestone quarry (WSQ), used in 

part to deposit radioactive wastes, is considered part of the WSP even though it is about 4 mi 

southwest of the plant. Figure 2-2 shows the layout of the WSP facilities. 

In April 1941, the U.S. Department of the Army acquired 17,232 ac surrounding what is now the WSP 

as the site for an explosives production facility known as the Weldon Spring Ordnance Works. From 

November 1941 to January 1944, the Atlas Powder Company operated the Ordnance Works for the 

Army to produce trinitrotoluene and dinitrotoluene explosives. The Ordnance Works began operating 

again in 1945 but was closed and declared surplus in April 1946. By 1949, all but about 2,000 ac had 

been transferred to the State of Missouri and the University of Missouri.

There are four periods for WSP:

• Site acquisition and development, 1954 to 1957;

• Operational, 1957 to 1966; 

• DOD control of the WSP, 1967 to 1985; and

• Remediation, 1985 to 2002.

WSP employment is covered under EEOICPA during only the operational and remediation periods, 

when the U.S. Atomic Energy Commission (AEC), U.S. Energy Research and Development 

Administration, and DOE had contractors and radioactive materials at the WSP. WSQ and WSRP 

employment is covered during those periods and during the DOD control period.
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Figure 2-1. Locations of WSP facilities (DOE 2001a). 

In 1956, approximately 220 ac of the former Weldon Spring Ordnance Works were transferred to AEC 

for construction and operation of a feed materials plant to process uranium and thorium ore 

concentrates, which operated from 1957 through 1966 (Army 1976). Construction was completed in 

February of 1957; initial operations began in June of 1957 (AEC 1958). Nuclear materials in the form 

of natural uranium (NU) concentrates were being stored at the site before the start of operations but, 

“since they were not processed, they did not engender operational losses” (Harris 1986). Therefore, it 

is reasonable to assume exposures before operational startup were negligible. Although the raffinate 

pits were physically part of the WSP, they are referred to separately in this document as the WSRP 

because they were managed separately from the WSP between the operational and remediation 

periods. 

In 1958, a 9-ac quarry site was transferred to the AEC and is referred to as the WSQ in this 

document. Although the WSQ was not on the WSP site proper, it is covered within the scope of this 

TBD.

In August 1967, the WSP was returned to Army control for construction of an herbicide production 

facility (Army 1976), but AEC retained custody of WSQ and WSRP. Decontamination of the 

transferred WSP facilities was attempted between 1968 and 1970, but abandoned because of cost. 

The Army never completed or produced any herbicides during this period.

DOE regained responsibility for the WSP in 1985 and began site characterization and remediation in 

1985. The quarry was placed on the U.S. Environmental Protection Agency (EPA) National Priorities 
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Figure 2-2. WSP and WSRP site layout (modified from Army 

1976, p. 176).

List (NPL) in 1987, and the listing was expanded to include the WSP and associated waste storage 

areas in 1989.

The following sections provide more detailed descriptions of these activities. These descriptions are 

summarized from Army (1976) and Meshkov et al. (1986) unless otherwise noted.

2.3 SITE ACQUISITION AND DEVELOPMENT, 1954 TO 1957

In August 1956, Congress approved the transfer of 205 ac of the former Ordnance Works property 

from the Army to AEC. An additional 15 ac were later transferred to the AEC for expansion of waste 

storage capacity. The AEC began designing a feed materials plant in 1954 and constructed the plant 

now referred to as the WSP in 1956 and 1957 on this property for processing uranium and thorium 

feed stocks into metal and intermediate products. This facility replaced a more limited plant of similar 

operational capability in St. Louis (on Destrehan Street). The WSP facility was specifically designed 

to process uranium mill concentrates (yellowcake) from the United States and Canada. These 

materials were shipped to the WSP site for sampling to determine payment. Fractions of the total mill 
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concentrates were processed through chemical treatment operations. Other fractions, after sampling, 

were shipped to other DOE facilities for further processing.

2.4 OPERATIONAL PERIOD, 1957 TO 1966

2.4.1 Processed Materials

WSP was operated for AEC by the Uranium Division of Mallinckrodt Chemical Works (MCW) from 

1957 to 1966 and processed materials from June 1957 to December 1966. Shutdown procedures 

were completed in 1967. DOE (2000a) estimated the employment at the site for the Uranium Division 

at about 600 employees, of whom about 300 would have handled radioactive materials.

In 1986, DOE prepared Historical Nuclear Materials Balance Report for the Former AEC-Owned 

Weldon Spring Chemical Plant (Harris 1986), which summarized the types and quantities of nuclear 

materials WSP received and processed. This report indicated that four types of nuclear materials 

were processed during the operational period of WSP: (1) NU, (2) depleted uranium (DU), (3) slightly 

enriched uranium (EU), and (4) natural thorium. The great majority of processed material was NU

(approximately 98% of the total mass). An average of 1.2 × 107 kg (1.4 × 104

 t) of uranium-containing 

material was processed per year (Harris 1986). Total material balance closures (i.e., percent of 

material accounted for) for the 10 years of plant operations were 99.94% for NU, essentially 100% for 

DU, and 99.27% for EU. An average of 3.1 × 105 kg (350 t) of natural thorium was processed per 

year from 1964 through 1966, with an associated total material balance closure of 98.52%. Table 2-1 

summarizes the total receipts by fiscal year of operation.

Table 2-1. Annual uranium and thorium mass receipts (kg) (Harris 1986).

Fiscal 

yeara NU DU EU

Natural 

thorium

1958b 8,000,407 128 0.4 44

1959 12,898,013 11,255 0 0

1960 15,032,283 30,203 0 0

1961 15,546,776 94,260 0 0

1962 16,009,091 22,225 0 0

1963 18,873,351 0 94,695 0

1964 16,661,427 47 265,323 13,111

1965 11,445,290 2,769 441,977 313,699

1966 7,077,000 6,936 27,700 614,693

1967 472,339 0 12,890 0

Totals 122,015,977 167,823 842,585 941,347

a. Fiscal year begins on July 1 of the previous calendar year and ends on June 30 of the calendar year 

corresponding to the designated fiscal year.

b. Includes startup period in fiscal year 1957.

Natural Uranium

NU was received as continental ore concentrates (e.g., yellowcake) from uranium-milling facilities and 

was refined to extract the uranium, after which the uranium was converted to various compounds and 

metal forms and shipped off site. Processing of NU was a continuous operation during the life of the 

plant.

The primary uranium concentrates at WSP consisted of 234U, 235U, and 238U in their natural 

abundances with very low concentrations of decay products. Historical documents report that WSP

did not receive the high-quality pitchblende ores that were processed at the MCW Destrehan Street 

facility in St. Louis (Ingle 1991). Although some plant documents mention the receipt or processing of 

“ores,” it appears that this term actually referred to ore concentrates (ORAUT 2009a, 2009b, 2009c).
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Decay products and other impurities including natural thorium (e.g., 232Th and 228Th) were present in 

the uranium ore concentrates. These materials and their associated quantities were considered a 

minor hazard in comparison with the uranium itself. The Weldon Spring Historical Dose Estimate

(Meshkov et al. 1986) estimates the offsite activities of 230Th and 226Ra in yellowcake to be 5% and 

1% of 238U activity, respectively. However, specific isotopic characterization of raffinates at WSP

indicates that the uranium mill processes that produced the yellowcake concentrates for both Fernald 

and WSP effectively removed the radium but were not effective in removing thorium, specifically 230Th. 

Measurements of the activity concentrations in Raffinate Pits 1, 2, and 3 can be used to determine the 

relationship between 230Th and other impurities during the initial uranium processing in Building 101 

before any separations occurred, as discussed in ORAUT-TKBS-0028-5, Weldon Spring Plant – 

Occupational Internal Dose (ORAUT 2017b). The shorter lived decay products 210Pb and 210Po, for 

which no raffinate measurements were made, should be assumed present at the same activity as the 

226Ra in raffinate pits. As indicated above, there is no suggestion in the historical records that WSP

ever processed the high-activity pitchblende, which contained significant concentrations of radium. 

The ore concentrates were a relatively small source of radon because most of the radium in the ore 

was removed in the milling process, which occurred elsewhere. Radium is the parent of radon in the 

naturally occurring decay chain.

Depleted Uranium

Uranium depleted in 235U below its natural isotopic abundance ratio was received and processed on 

an intermittent basis as metal and various intermediate chemical forms. This form of uranium was 

used primarily in product development activities and flow-sheet improvements and was confined 

primarily to pilot plant activities.

Enriched Uranium

Uranium enriched to 1% or less 235U by weight was also received and processed on an intermittent 

basis. This type of uranium was typically in the form of scrap metal or residues. The uranium 

contents were recovered, processed to various chemical forms, and shipped off site. The coefficient 

of variation about the values assigned to all flows of EU was slightly greater than that for NU, primarily 

because of the heterogeneous nature of receipts.

Natural Thorium

Natural thorium was typically received in either nitrate or oxide form and processed on an intermittent 

batch basis in the refinery and oxide production and firing systems. Only a limited area of the WSP

(refinery and pilot plants) processed the material. In addition, Dupree (1979) stated that 

approximately 3.6 × 105 kg (400 t) of “impure thorium nitrate and enriched uranium” were processed 

starting in 1965.

Thoron is the second progeny of 228Th and, a couple of weeks after the processing of thorium ores for 

thorium purification, can be considered to be in full equilibrium with the parent, 228Th. Thorium-228 is 

the third progeny of the long-lived 232Th and is generally in 40% to 65% equilibrium for the materials 

WSP processed. The degree of equilibrium is dependent on both the decay of 228Th (without 

replenishment from the 5.7-year half-life of 228Ra) after removal of the progeny and the time it takes 

the 228Ra to build into equilibrium with 232Th.

Thoron was present and a portion was released during the processing and storage of thorium at the 

WSP and the associated waste storage locations. The thoron, with its progeny, was a potential 

source of internal exposure in the thorium process buildings and at waste storage locations. 

Table 2-2 provides the half-life information for thoron and its progeny. 
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Table 2-2. Thoron and progeny (ORAUT 2017a). 

Isotope Half life Atoms/7.5 pCi MeV/atom

PAEC 1a MeV per 

7.5 pCi

Radon-220 56 s 23 14.6 335

Polonium-216 0.15 s <1 Included with Rn-220b Included with Rn-220

Lead-212 10.64 hr 15,476 7.8 1.21E+5

Bismuth-212 60.6 min 1,469 7.8 0.12E+5

Polonium-212 0.3 μs Not applicable Included with Bi-212b Included with Bi-212

Thallium-208 3 min 73 No alpha 0

Total Not applicable Not applicable Not applicable 1.33E+5

a. PAEC = potential alpha energy concentration.

b. The alpha energy is emitted by Po-216 and Bi-212. While Bi-212 directly emits an alpha only 36% of the time, the 

other 64% of the time it emits a beta and becomes Po-212, which then emits an alpha almost immediately (304 ns

half-life). The average alpha energy released by a Bi-212 decay is then 7.8 MeV (6.07 MeV × 0.36 + 8.785 MeV × 

0.64). Because Po-216 ultimately decays by two alphas (Po-216 and Bi-212), the alpha energy released per Po-216 

atom is 14.6 MeV. Lead-212 and Bi-212 both decay with an effective alpha energy of 7.8 MeV.

Recycled Uranium

Some 1961 shipments that came from Fernald could have included some quantities of RU. In 1999, 

DOE initiated the complex-wide Recycled Uranium Mass Balance Project that identified WSP as a site 

that likely received RU in relatively small quantities beginning in 1961 (DOE 2000a). The significance 

of these receipts of RU is that this material contains trace amounts of residual transuranic elements 

including plutonium and neptunium, fission products such as technetium, and reactor-produced 

uranium isotopes such as 236U (DOE 2000a). Site records do not include the level of detail necessary 

for an accurate estimate of the amount of recycled material WSP received and processed. It is known 

that the plant received shipments of uranium materials from other DOE sites that processed and 

shipped RU from fiscal years 1962 to 1967 (the period of RU shipment), but the amounts of RU 

versus NU are not known. Due to the lack of information about RU quantities, it is assumed that all 

uranium receipts beginning in 1961 were recycled (DOE 2000a) and contain RU contaminants. This 

assumption is based on the fact that Fernald received its first significant quantity of RU from Hanford 

in 1961 (ORAUT 2017a, p. 21), and because Weldon Spring Plant received most of its RU from

Fernald (DOE 2000a, p. 121). The RU contaminants and their activity levels at the site are based on 

ORAUT-TKBS-0017-5, Feed Materials Production Center – Occupational Internal Dose (ORAUT 

2017a) and stated in ORAUT-TKBS-0028-5, Weldon Spring Plant – Occupational Internal Dose 

(ORAUT 2017b).

2.4.2 Plant Processes and Operations

The main activity at WSP was to convert uranium concentrate to uranium trioxide (UO3), uranium 

tetrafluoride (UF4), and uranium metal. The received material was yellowcake (uranium concentrate). 

A wet solvent extraction method was used for UF4 production. Before entering the refinery, the ore 

concentrate underwent a sampling and preparation process in the sampling plant.

2.4.2.1 Uranium Concentrate Sampling

Building 101 was the sampling building. Ore concentrate arrived in drums of about 60% to 

70% uranium. The drums were opened and sampled using one of two sampling methods – auger or 

mechanical – after which the drums were emptied into hoppers at the top of the building. From the 

hoppers, material was transferred to portable hoppers for transfer to the refinery (Figure 2-3). 

Yellowcake dust was collected in three large dust collectors, each with its own stack. Some 

yellowcake was repackaged in drums and shipped out; the rest was put into hoppers and moved to 

Building 103 for digestion. The dust collection system was vacuum cleaned from time to time, and the 

collected dust was reprocessed. Uranium dust was washed off the drums, equipment, and floors, and 

this dust was also reprocessed.
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Figure 2-3. Sampling plant flow diagram (adapted from Army 1976).

2.4.2.2 Uranium Trioxide Production

The UO3 (orange oxide) was produced, or refined, in three steps: digestion, purification by solvent 

extraction, and denitration (Figure 2-4). Building 103 was the first building of the refinery plant. 

Concentrate was brought in hoppers to the top of the building where there was one dust collector with 

one stack to collect yellowcake dust. The concentrate was heated and digested with nitric acid to 

produce a solution of uranyl nitrate. The digested material was passed to Building 105 in liquid form 

where pure uranyl nitrate solution was extracted and remained in liquid form. The highly purified 

uranyl nitrate solution was evaporated and pumped to gas-fired denitration pots in Building 103 where 

the remaining water was removed, producing pure UO3. According to Meshkov et al. (1986), this was 

the dustiest part of the process. Impurities from the purification process were bled off in the raffinate, 

which was pumped to pits. This raffinate contained a conglomerate of radionuclides including thorium 

and radium in small concentrations.

The radon trapped in the ore concentrates was released during the acid digestion process in 

Building 103. The offgasses containing radon and nitrogen oxides from the digestion process were 

sent to the acid recovery plant (Building 108). This plant was the prime source of radon emission, 

which was estimated as being between 12 and 34 Ci/yr based on throughput (Meshkov et al. 1986, 

p. 48).

2.4.2.3 Uranium Tetrafluoride Production

The UO3 was packaged into transfer hoppers and transferred from Building 103 to the top of 

Building 201, the green salt (UF4) plant. Figure 2-5 shows the reduction and hydrofluorination process 

WSP used to produce UF4. Hydrogen gas reduced UO3 to uranium dioxide (UO2).
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Figure 2-4. Digestion, purification, and denitration (adapted from Army 1976).

Figure 2-5. Reduction and hydrofluorination process (adapted from Army 1976).

The next step was hydrofluorination, in which UO2 was transformed to UF4 or green salt. Excess 

hydrogen fluoride (HF) gas from the process was filtered through carbon filters to recover uranium, 
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which was recycled to black oxide (U3O8). Discharge from the UF4 reactor system was mechanically 

collected, crushed, and blended to obtain desired particle sizes. There were two additional dust 

collectors on the roof of Building 201 associated with the system to collect UF4 dust, and there was a 

reverter in the building to convert UF4 into U3O8. 

2.4.2.4 Uranium Tetrafluoride Conversion

UF4 (green salt) was packaged in transfer hoppers and moved to Building 301, the metals plant. 

Magnesium was used to convert UF4 to solid uranium metal in a multistep process. Figure 2-6 depicts 

this process. The reaction occurred in refractor-lined steel “bomb” shells, which were charged with a 

mixture of green salt and magnesium chips. Green salt and magnesium were mixed in a blender; the 

mixture was then placed in individual steel shells at the filling machine and sent to the furnaces for 

firing. In the furnace, the shell was heated to about 500°F and the charge was ignited electrically. 

Once ignited, the reaction proceeded spontaneously. Complete shells were moved to an outdoor 

cooling pad for about 3 days. The process generated green salt dust. UF4 and magnesium fluoride 

(MgF), with 1% to 2% of residual uranium in various forms, were discharged from several dust 

collectors at the ground level on the south side of the building. A rotary kiln in Building 301 calcined 

uranium metal chips to recover the uranium from scrap and to convert them to U3O8. One standard 

dust collector was used for the dusty discharge, mostly U3O8, that was produced in this operation.

Figure 2-6. UF4 conversion to uranium metal (adapted from Army 1976).

2.4.2.5 Products Manufacturing

Uranium fuel cores were produced in Building 301. Uranium billets were extruded to rods to produce 

cores for use in reactors. The rods, approximately 22 ft long, were straightened, cut to lengths, heattreated, degassed, and fed to a six-spindle automatic machine, which turned off a thin layer of 

material from the outside diameter and sectioned them into about 8.5-in. lengths. The rough cores 

were then treated at 950°F in a vacuum furnace to remove hydrogen gas from the metal. Degassed 
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cores were heat treated in molten salt at 1,350°F and quenched in water at 130°F to randomize the 

grain structure. Cores were further machined to remove the warp and oxide layer that resulted from 

heat treatment and degassing. Holes were drilled in the solid core, and it was reamed to final size. 

Good cores were inspected in an ultrasonic machine to ensure that the grain structure was neither too 

small nor too large. A dimensional inspection was performed to ensure that specifications were met. 

All acceptable cores were packaged in boxes and shipped by rail directly to reactor sites.

2.4.2.6 Thorium Processing

Natural thorium was received in either nitrate or oxide form and processed on an intermittent basis in 

the refinery and oxide production and firing systems. In 1965 and 1966, first pure and then impure 

thorium oxide were processed initially on a pilot scale in Buildings 403 and 404 and later on a larger 

scale in Buildings 103, 105, and 301 (Harris 1986).

An average of 3.1 × 105 kg (350 t) of natural thorium was processed per year during 1964 through 

1966, with an associated total material balance closure of 98.52%. MCW (1966) summarized 

operations with thorium as shown in Table 2-3. Thorium process wastes were deposited in Raffinate 

Pit 4. In the table, “TNT” abbreviates thorium nitrate tetrahydrate.

Table 2-3. Chronological summary of thorium operations. 

Operation title Building 1963 1964 1965 1966

TNT crystal repackaging 403 Nov–Dec May–Sep None None

TNT crystal repackaging 301 None Oct–Dec None None

Denitration of TNT crystals & sol 

drying-hand unloading

103 Nov–Dec May–Aug None None

Denitration of TNT crystals & sol 

drying-vacuum uploading

103 None Sep–Dec None None

Denitration of TNT liquor & sol 

drying-vacuum uploading

103 None None Jan–Jul None

Denitration by fluid bed-product 

packaged in drums

403 None None May–Jul None

Denitration by fluid bed-liquor feed & 

sol product

403 None None Aug–Dec Jan; Jun–Sep

Denitration of TNT liquor-scoop & 

pail transfer to sol tank

103 None None Oct–Nov None

Sol drying-vacuum uploading 103 None None Aug–Dec Jan; Jun–Sep

ThO2 high firing-recast furnace 301 Nov–Dec May–Sep None None

ThO2 high firing-billet heaters 301 None Oct–Dec Jan–Dec Jan; Jun–Sep

ThO2 product packaging 403 Nov–Dec May–Jul; Sep–Dec Jan–Sep None

ThO2 product packaging 103 None Aug None None

ThO2 product packaging 301 None None Oct–Dec Jan; Jun–Sep

Rotary kiln calcining of sump cake 301 None None None Apr–Jul

Digest feed repackaging 101 None None None Apr–Aug

Scrap digestion & raffinate disposal 103 None None None May–Sep

Extraction 105 None None None Jun–Sep

2.4.2.7 Analytical and Research Laboratories

The Analytical and Research Laboratories were housed in Building 407. The Analytical Laboratory 

had four sections. The Production Section had laboratories for process control, uranium 

accountability, sampling, and specifications testing. The Spectrographic Section measured impurities 

in raw materials and finished products. The Method Development Section provided analytical 

procedures for the laboratory. Equipment included infrared and ultraviolet spectrophotometers, vapor 

phase chromatograph, X-ray spectrometer, ultra-high-vacuum equipment, an isotope ratio mass 

spectrometer, and a time-of-flight mass spectrometer. The Special Analysis Section performed 
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analytical work for the research laboratory and pilot plants in addition to running production and 

uranium inventory samples.

The Research Laboratory consisted of three sections. The Dry Chemistry Section was concerned 

with problems in fluoride chemistry and with metallurgical studies. The Wet Chemistry Section 

worked on such studies as the digestion and extraction of raw material feeds, solvent quality, uranyl 

nitrate purity, and nitric acid recovery. The Instrumental Techniques Section used a wide variety of 

optical equipment: X-ray diffraction equipment for qualitative and quantitative analysis and electron 

and optical microscopes for particle-size distribution studies, identification of minerals, and studies of 

physical properties.

2.4.2.8 Pilot Plants

Buildings 403 and 404 housed the WSP and Metallurgical Pilot Plants, respectively. Both had 

development facilities on a scale between those of the laboratory and the plant. After new processes 

and equipment were demonstrated on a small scale in the laboratory, they were investigated further in 

the pilot plants. Research was performed on the design, installation, and operation of an integrated 

fluid-bed system for producing uranium trioxide, uranium dioxide, and green salt. The WSP also 

studied a process for the simultaneous denitration of uranyl nitrate and reduction of UO3. The 

Metallurgical Pilot Plant was equipped for large-scale development of the bomb-reduction step of the

process.

2.4.2.9 Raffinate Pits

The processing of uranium and thorium generated several chemical and radioactive waste streams, 

which were piped to the raffinate pits. The solids settled to the bottoms of the pits, and the 

supernatant liquids were decanted to the plant process sewer that drained off the site to the Missouri 

River. Of the amount of discards (i.e., material known to have been disposed of via plant stacks, 

sewers, and raffinate pits rather than shipped off the site), approximately 67% of the uranium and 

essentially all of the thorium went to the raffinate pits (Harris 1986).

Between 1958 and 1964, to contain process wastes from the plant, four raffinate pits were 

constructed in the southwest portion of the site for wastes from the plant (NLO 1977). Pits 1 and 2 

were constructed in 1958 and were used for almost 2 years. The design volume of each of these two 

pits was 14,000 m3 (500,000 ft3

) (NLO 1977).

Because of the high production rate, the first two raffinate pits filled rapidly, requiring the construction 

of the third and eventually the fourth. Pit 3 was constructed and put into operation in 1959, with a 

design volume of 127,000 m3 (4.5 × 106 ft3

). Pit 4 was constructed and put into operation in 1964, and 

its design volume was 340,000 m3 (1.2 × 106 ft3

) (NLO 1977, p. 20).

The uranium process wastes contained relatively low-level concentrations of uranium. The 

radionuclide of most concern in the raffinate pits was 230Th, due to its high activity concentration and 

its radiotoxicity. It is estimated that 152,382 kg of NU, 46 kg of DU, and 2,808 kg of EU were 

discharged to the raffinate pits (DOE 2000a, Table 2-23, p. 86).

Raffinate Pits 1, 2, and 3 received mostly uranium raffinates, and Pit 4 received both uranium and 

thorium raffinates. In the first three pits, 230Th constituted greater than 80% of the total activity. An 

upper estimate of the 230Th activity in the ore concentrates is 100% of the 234U activity (its parent), or 

50% of the total uranium activity (approximately 0.34 nCi/mg U). Some natural thorium (e.g., 232Th 

and 228Th) was present in the uranium ore concentrates, which was also separated and sent to the 

raffinate pits.
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2.4.2.10 Weldon Spring Quarry

In 1958, AEC acquired the WSQ, which was previously part of the Army’s Ordnance Works (DOE 

1985). The WSQ was first used for storing radioactive waste in 1959, when an estimated 150 m3

(5,400 ft3

) of drummed 3.8%-thorium residues were placed there. In 1966, approximately 13,500 ft3 of 

drummed and bulk 3%-thorium residues were deposited in the WSQ.

Before 1963, the quarry only contained drummed thorium wastes that were likely submerged and not 

a significant source of radon. In 1963 and 1964, an estimated 38,000 m3 of uranium- and radiumcontaminated rubble, equipment, and soil were placed in the quarry after demolition of the Destrehan 

Street site, with a majority of this waste unsubmerged, which provided a potential source of radon 

exposure (MCW 1967, p. 16; Haroun et al. 1990, p. 20). Measurements in the quarry area in the late 

1970s and early 1980s (before remediation) averaged 0.65 ± 0.41 pCi/L, which indicates the quarry 

was not a major source of radon (Meshkov et al. 1986, p. 101). As in the case of the raffinate pits, 

this value is limiting for the operational period.

2.4.3 Plant Operations and Radioactive Material of Concern Summary

Table 2-4 lists the WSP buildings, summarizes the activities that took place in them, and identifies the 

potential radionuclides of concern (MCW 1962, ca. 1964; Meshkov et al. 1986).

2.5 U.S. DEPARTMENT OF DEFENSE CONTROL PERIOD, 1967 TO 1985

In early 1966, AEC decided to close WSP at the end of the year, which resulted in a declining 

workforce as employees sought other employment. Decontamination of the buildings and equipment 

for unrestricted use were not part of the AEC shutdown directive. Under the shutdown procedures, 

hoppers and process lines were emptied and dust collectors and other points of material accumulation 

were cleaned out. Access ports were used to remove as much of the pure uranium compounds as 

possible from the production equipment. By the end of 1967, these shutdown activities were 

terminated and the facilities awaited turnover to the Army for use as an herbicide facility. The transfer 

of facilities to the Army began in March 1968.

At shutdown, only a few pounds of pure compounds were present in any one piece of equipment. 

The bulk of the remaining compounds was in building sumps and secondary pieces of process 

equipment and piping without routine access ports. For a short time after closure, some of the 

buildings were used for interim storage of drummed yellowcake from other mills, which was later 

shipped to various plants for refining and processing.

AEC transferred the WSP facility to the Army in 1967 (DOE 2003) for the purpose of using portions of 

the feed materials plant for the production of Agent Orange herbicide to meet needs in Southeast 

Asia. However, AEC maintained control of Building 434 (which had been used for the storage of ore 

concentrates), a 51-ac tract encompassing the four raffinate pits (WSRP), Building 438, and the WSQ.

The Army selected Buildings 103 and 105 for herbicide production, with blending and packaging to 

occur adjacent to Building 101. Construction of the herbicide facility began in December 1968 but 

was terminated when the project was canceled in early 1969. Cleanup and shutdown work was 

conducted on the site until June 1969. The Army began decontamination and equipment removal in 

Buildings 103 and 105 in March 1968. About 6,000 yd3 of highly contaminated and unrecoverable 

material were hauled to the quarry 4 mi south on Highway 94. About 2,400 tons of contaminated 

scrap was shipped via rail and truck to a Knoxville, Tennessee, contractor. Another AEC contractor, 

National Lead Company of Ohio (NLO), received 20 railcars and one truckload of stainless-steel 

piping, valves, vessels, and spare parts. Approximately 135 barrels of uranium oxide were recovered 

from the buildings. A high-pressure hot-water solution containing an acidic wetting agent was used to 
 

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Table 2-4. Description of WSP buildings and operations.

a

Building Description Dates Operations performed Potential radionuclide exposures

101 Sampling Plant June 1957–

1966

Preparation and sampling building designed to process 

approximately 75 ton/d of low-assay uranium ore 

concentrates. Housed equipment and facilities for 

drying, grinding, screening, blending, and sampling of 

ore concentrates and process residues. Incoming ore 

concentrates and residues were stored in drums on 

concrete pad.

NU dust, 

Ra-226, 

Th-230, 

Po-210, 

Pb-210, 

Rn-222 and its short-lived progeny, 

Th-232 and progeny (in 1966)

Area 102 

A&B

Refinery Tank 

Farm

June 1957–

1966

Provided facilities for unloading, storing, and transferring 

liquid process material required in the refinery operation 

that were supplied or handled in tank-car and tank-truck 

quantities.

NU dust, 

Ra-226, 

Th-230, 

Po-210, 

Pb-210, 

Rn-222 and its short-lived progeny, 

Th-232 and progeny (in 1966)

103 Digestion and 

Denitration

1957–1966 Originally the nitrating, denitrating, and raffinate 

processing and storage area.

The northern digestion section received uranium ore 

concentrates that were digested and transferred as a 

slurry to Building 105 where the solvent was purified 

by extraction.

The middle denitration section received the purified 

uranium nitrate solution, which was denitrated to yield 

uranium nitrate solution, which was further denitrated 

to yield UO3. During later years, thorium products 

were also processed in this building.

NU dust (as yellowcake and uranium trioxide), 

Ra-226, 

Th-230, 

Po-210, 

Pb-210, 

Rn-222 and its short-lived progeny, 

Th-232 and progeny (beginning November 

1963)

104 Lime Storage After 1956 Facility for storing lime for acidity neutralization of 

raffinate solution.

NU dust (as yellowcake and uranium trioxide), 

Ra-226, 

Th-230, 

Po-210, 

Pb-210, 

Rn-222 and its short-lived decay products, 

Th-232 and decay products (beginning 

November 1963)

105 Extraction Feb 1957–

1966

Purification building. Previously used for producing a 

highly purified uranyl nitrate hexahydrate (UNH) solution 

by means of extraction columns, process vessels, 

evaporators, and tributyl phosphate and hexane 

reaction tanks.

NU dust, 

Ra-226, 

Th-230, 

Po-210, 

Pb-210, 

Rn-222 and its short-lived progeny, 

Th-232 and progeny
 

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Building Description Dates Operations performed Potential radionuclide exposures

106 Refinery Sewer 

Sampling

Unknown Used as a sampling station for process waste streams. Uranium dust, 

Rn-222 and short-lived progeny

108 Nitric Acid Plant 1957–1966 Used for recovering and reconcentrating nitric acid and 

oxides of nitrogen.

Uranium dust or thorium (in 1966), 

Rn-222 and short-lived progeny

109, 110 West Drum 

Storage, East 

Drum Storage

Unknown Used to store drums containing ore concentrates and 

process residues.

Unknown

201 Green Salt 

Building

Feb 1958–

1966

Used for converting UO3 to UO2 and UF4. Uranium exposure as green salt dust or 

natural thorium (1965–1966)

202 A&B Green Salt Tank 

Farm

1957–1966 Used for tank car unloading and storage of hydrofluoric

acid and ammonia.

Unknown

301 Metals Building Apr 1958–

1966

Used for converting UF4 to uranium metal. Uranium as green salt dust and U3O8 or 

natural thorium (1965–1966), 

Th-232 and decay products (beginning 

November 1963)

302 Magnesium 

Storage Building

1957–1966 Powdered magnesium handling building used for 

storage of magnesium.

U, Th, and their progeny

Pad 303 Storage Pad Unknown Served as a material storage pad. Unknown

401 Steam Plant 1956–1966 Steam-generating plant including coal conveyor and 

coal yard.

Unknown

403 Chemical Pilot 

Plant

1957–

unknown

Demonstration of pilot operations. NU dust, 

Ra-226, 

Th-230, 

Po-210, 

Pb-210, 

Rn-222 and its short-lived decay products, 

Th-232 and decay products (starting 

November 1963)

404 Metallurgical Pilot 

Plant

1957–

unknown

Provided facilities for metal processing studies, ceramic 

work, and metal testing; housed Metallurgical Pilot 

Plant.

Uranium as green salt dust and U3O8 or 

natural thorium (1965–1966)

405A & B Pilot Plant 

Maintenance

1957 Building 405A was a small shop and storage building 

spare pilot plant equipment storage. The dust collectors 

and vacuum cleaning system for Buildings 403 and 404 

were on Pad 405B.

Unknown

406 Warehouse 1956 Served as a warehouse and office area. Unknown
 

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Building Description Dates Operations performed Potential radionuclide exposures

407 Laboratory 1957 Used as an analytical chemistry laboratory. NU dust, 

Ra-226, 

Th-230, 

Po-210, 

Pb-210, 

Rn-222 and its short-lived decay products, 

Th-232 and decay products (1965–1966)

408 Maintenance and 

Stores

1956 Contained numerous maintenance shops, office area, 

garage, receiving and shipping area, decontamination 

room, and a large storage area.

Unknown

409 Administration 1957 Contained offices for administrative staff. Unknown

410 Services Building 1957 Contained the main gate, administrative offices, plant 

security office, health and safety office, kitchen, dining 

room, laundry facility for contaminated clothing, and 

clean and contaminated locker rooms with shower 

facilities.

Unknown

412 Electrical 

Substation

Unknown Substation for electrical supply. Unknown

413 Cooling Tower 

and Pump House

Unknown Water-cooling tower and pump house. Unknown

414 Scrap 

Classification and 

Equipment 

Storage

1956 Served as a salvage shop and equipment storage 

space.

Unknown

415 Process 

Incinerator

Unknown Incinerator for process materials. Unknown

417 Paint Shop Unknown Served as the paint shop. Unknown

426 Water Tower Unknown Used for water storage (elevated water storage tank). Unknown

427 Primary Sewage 

Treatment Plant

Unknown Served as the primary sewage treatment plant for the 

site.

Unknown

428 Fuel Gas Plant Unknown Storage facility for fuel gas. Unknown

429 Water Reserve 

Facilities

Unknown Water storage (pump house and ground storage tank). 

Also noted to have been a propane gas storage facility.

Unknown

430 Ambulance 

Garage

Unknown Used as an ambulance garage. Unknown

43l Laboratory Sewer 

Sampler

Unknown Used as a sampling station for process waste streams. Unknown

432 Main Sewer 

Sampler

Unknown Used as a sampling station for process waste streams. Unknown

433 Garage Unknown Large equipment garage area. Unknown

434 Storage Unknown Ore concentrate storage building. Unknown
 

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Building Description Dates Operations performed Potential radionuclide exposures

435 Storage Unknown Salvageable equipment storage. Unknown

436 Storage Unknown Salvageable equipment storage. Unknown

437 Records 

Retention Building

Unknown Facility used for storage and retention of records. Unknown

438 Storage Unknown Salvageable equipment storage. Unknown

439, 443 Fire Training and 

Storage Building

Unknown Facility used for fire training purposes and storage. Unknown

441 Cylinder Storage Unknown Facility used for storage of compressed gas cylinders. Unknown

a. Adapted from Army (1976).
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partially decontaminate Buildings 103 and 105. Portions of some concrete floors were removed and 

covered with tar and new concrete to mask radiological contamination. In June of 1969, the Kansas 

City District of the U.S. Army Corps of Engineers obtained custody of the 169-ac tract containing the 

WSP. Because the herbicide production program was cancelled in 1969, no major activities took 

place between 1969 and 1974.

DOE and its predecessors did not have contractors performing work on the 52-ac WSRP area or the 

9-ac WSQ area until August of 1975, when it contracted with NLO to perform environmental 

monitoring in the pits and the quarry. In 1981, Bechtel National assumed management and 

maintenance responsibility for the pits and quarry. In 1985, custody of the chemical plant was 

transferred from the Army to DOE (DOE 2017).

2.6 REMEDIATION PERIOD, 1985 TO 2002

In 1985, DOE proposed designating control and decontamination of the chemical plant, raffinate pits, 

and quarry as a major project to be called the Weldon Spring Site Remedial Action Project

(WSSRAP). In July 1986, a DOE project office was established on the site, and the project 

management contractor for the WSSRAP was a partnership of MK-Ferguson Company and Jacobs 

Engineering Group. The quarry was placed on the EPA NPL in July 1987. The chemical plant and 

raffinate pits were added to the NPL in March 1989.

The purpose of the WSSRAP was to eliminate potential hazards to the public and environment and to 

make surplus real property available for other uses to the extent possible. The scope of work 

included dismantling the 44 WSP buildings and structures and disposing of both radiologically and 

chemically contaminated structural materials and soils. The project also disposed of as much material 

as possible (including water, sludge, abandoned waste materials, and structural materials) from the 

raffinate pits, quarry, and nearby properties (DOE 2000b).

The Record of Decision for the Management of the Bulk Wastes at the Weldon Spring Quarry was 

finalized in March 1991 (EPA and DOE 1991). The quarry bulk wastes were excavated and placed in 

the Temporary Storage Area (TSA) at the WSP site based on an accelerated cleanup strategy 

involving limited characterization, a focused remedial investigation/feasibility study (RI/FS), and a 

limited baseline risk evaluation. Excavation of approximately 120,000 yd3 of WSQ bulk wastes was 

complete in October 1995 (DOE 2003). Material at the TSA was eventually placed in the onsite 

engineered disposal facility referred to as the Disposal Cell. After bulk waste excavation, the selected 

remedy for residual contamination at the quarry site was to use long-term monitoring to verify that 

conditions at WSQ remain protective of human health and the environment.

Remedial investigations were conducted at the chemical plant and raffinate pits areas in 1988 and 

1989 under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980

RI/FS process. These investigations included characterization of groundwater, onsite soil 

contamination, radiological contaminants in the raffinate wastes, and contaminated sediment in offsite 

surface drainages, lakes, springs, and other surface water. The Record of Decision for Remedial 

Actions at the Chemical Plant Area of the Weldon Spring Site (DOE 1993a) identifies the selection of 

the final remediation and disposal method for the chemical plant and bulk wastes for the quarry (DOE 

2003). Remediation activities included the removal of contaminated soil, demolition and removal of 

remaining concrete pads and foundations that supported the 44 structures and buildings, removal and 

treatment of the raffinate pit wastes, and disposal of site wastes in an onsite engineered disposal 

facility (DOE 2004a). Remediation via removal was complete in 2002, and DOE decided that 

remediation of the shallow groundwater aquifer under the former WSP would involve institutional 

controls and monitoring to achieve remediation objectives (DOE 2004a).
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Several temporary staging areas and process structures were constructed or commissioned for the 

purpose of treating or storing excavated wastes and raffinate pit water during the remediation 

process. Two water treatment facilities were used: a Quarry Waste Treatment Plant and the Site 

Water Treatment Plant (SWTP). A TSA for the WSQ bulk wastes was an area designed and 

designated on the WSP to store excavated waste before placement in the Disposal Cell. A Chemical 

Stabilization and Solidification (CSS) facility operated to produce a grout for use in the engineered 

disposal facility. By mixing the contaminated raffinate pit sludges with fly ash and Portland cement, 

the plant provided a means for managing the contaminants as well as a material to fill voids and 

increase the structural stability of the facility. The full-scale CSS plant began operation in mid-1998. 

On November 13, 1998, the CSS plant completed processing sludge from Pit 3, treating 

approximately 122,000 yd3 of sludge since April 1998 including more than 75 million gal of water with 

an average of 8% to 10% solids. The sludge was screened for oversized materials, then thickened 

with a polymer before it was blended with binder materials and transferred to the Disposal Cell. 

Approximately 188,000 yd3 of grout were produced in the process. Demolition work on the SWTP 

was initiated on April 23, 1999, with activities complete in late June 1999. During 1999, Raffinate Pits 

3 and 4, the Ash Pond Area, and the northern and southern portions of the TSA were remediated and 

their associated contaminants were placed in the Disposal Cell. Final site grading for the raffinate 

pits, Ash Pond, TSA, SWTP, Frog Pond, and material storage areas was performed in 2000. 

Construction of the Disposal Cell was completed in 2001, and nearly 1.5 million yd3 of contaminated 

wastes had been placed in it (DOE 2004b; DOE 2002). 

2.7 RELEASES TO THE OUTDOOR ENVIRONMENT

The following discussion is restricted to the periods for which the WSP has been listed as a “covered 

facility” according to the DOE Office of Environment, Health, Safety and Security list (DOE 2017), 

which are from 1955 to 1967 and from 1975 to 2002. Operations did not begin until 1957, so this 

discussion is limited to a beginning year of 1957. The site did not have AEC or DOE contractors 

performing work at WSP outside of these periods (DOE 2017). Table 2-5 summarizes the activities 

that released radionuclides to the WSP environment.

Table 2-5. History of radioactive effluent-generating activities (1957 to 2002). 

Date Event

1957–1966a Operation of uranium feed materials plant.

Uranium concentrate converted to UO3, UF4, and uranium metal.

Some thorium processing.

Raffinate from the processing removed to raffinate pits.

14,500 MT of uranium materials received for processing and sampling per year from 1958 

to 1964.

Some thorium processed from 1965 to 1966.

Uranium and thorium residues disposed of in the WSQ. 

December 1966a Plant closed, hopper and process lines emptied, dust collectors cleaned out.

1975–1985 Site remained essentially undisturbed.

1985–2002 Remediation involving excavation of contaminated soils and rubble.

a. Expanded from Meshkov et al. (1986).

2.7.1 Airborne Emissions

According to Meshkov et al. (1986), air concentrations of uranium were measured during the WSP 

operational period along the plant site perimeter, around buildings on the site, and at the south edge 

of the quarry. Air concentrations of radon were measured from 1979 through 2001 around the 

chemical plant, pits, and quarry perimeters (Meshkov et al. 1986; Weidner and Boback 1982; Bechtel 

1983a, 1983b, DOE 1984 to 1986a, 1987, 1988a, 1989 to 1992, 1993b to 1999, 2000c, 2001a, 2002). 

Air concentrations of particulates were measured during some of the postoperational years. This 

information suggests that air emissions were of potential concern not only during operational activities 
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when radionuclide-laden dust was created, but also from subsequent contamination of the 

surrounding terrain.

The total amount of uranium emitted to the atmosphere during the operational period (1957 to 1966) 

has been estimated from monitoring data (Meshkov et al. 1986) and a materials balance study (Harris 

1986). Table 2-6 lists the buildings that produced most of the air discharges and summarizes the 

types of discharge and stack heights. Table 2-7 summarizes the reported atmospheric discharges 

from the materials balance study, which were engineering estimates derived from airflows and other 

process factors along with stack monitoring data. Based on these two methods, the amount of 

uranium activity emitted from the plant was estimated to range between approximately 1 and 5 Ci/yr. 

Release rates for uranium decay products (230Th, 226Ra, and 210Pb) were also estimated by Meshkov 

et al. (1986) as a fixed percent of the (estimated) amount of released 238U. An estimate of radon 

release based on the amount of uranium processed during the period ranged from 12 to 34 Ci/yr.

Table 2-6. Location and height of stacks at the WSP (Meshkov et al. 

1986, Table 3.2).

Building 

number

Number 

of stacks Discharge

Height of stack 

(m)

101 2–3 Yellowcake dust 35

103 1 Yellowcake dust 23

103 Several UO3 Various

201 6 UO2, UF4, and U3O8 14–34

301 Several UF4 and MgF with 1% uranium 23

301 1 U3O8 Unknown

Table 2-7. Estimated annual discharges to stacks (kg).

a

Fiscal yearb NU DU EU Natural thorium

1958 No data No data No data No data

1959 No data No data No data No data

1960 7,200 No data No data No data

1961 7,200 0 0 0

1962 7,200 0 0 0

1963 7,200 0 0 0

1964 7,483 0 0 0

1965 4,200 0 300 0

1966 4,158 0 0 0

1967 100 0 0 0

Total 44,741 0 300 0

a. From Table 7 in DOE (1986b). 

b. Fiscal year begins on July 1 of the previous calendar year and ends on June 30 of the calendar year 

corresponding to the designated fiscal year.

Beginning in 1981, annual environmental monitoring reports have provided estimates of air 

concentrations of particulate radionuclides and of radon at the WSP and WSQ. These estimates 

reflect emissions during the latter part of the Army’s custody (until 1985) and throughout remediation 

activities (until 2002). Because WSP remained in the environmental monitoring phase from 1975 to 

1985, data from the period from 1981 to 1985 could be useful for estimating emissions from 1975 to 

1980.

2.7.2 Waterborne Emissions

Waterborne emissions from WSP have been a result of discharge of solubilized radionuclides to 

surface water or groundwater. The four raffinate pits and the WSQ presented conditions where 
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contaminated sludge, soil, and rubble were covered or partially covered with standing water. During 

the operational period (1957 to 1966), the WSRP were a source of radionuclides that discharged to 

surface water. After WSP operations ended in 1966, a small but continuous discharge at the process 

sewer outfall occurred (Weidner and Boback 1982). During operations and in the years after plant 

closure, leaching of sediments in the pits and quarry provided a route of discharge to groundwater 

(Weidner and Boback 1982).

The four raffinate pits received neutralized residues and waste streams from the various processing 

steps at the WSP (Ficker 1981). The sludges in all the pits are essentially the same with the 

exception of those in Pit 4, because the latter was used predominantly during thorium processing. 

The pits were used as settling lagoons; the solids would settle out as a sludge, and the remaining 

supernatant would overflow to the plant process sewer. The solids were mostly acid insoluble 

compounds from the original ore material as well as hydroxides and precipitates that formed when the 

raffinates were neutralized with lime.

About 30% of the residues in Pits 1, 2, and 3 came from the uranium metal production step. 

Magnesium fluoride was produced as a scrap material during the reduction of UF4 to uranium metal, 

and the slag contained about 5% uranium. This uranium was leached from the slag and then washed 

to remove the remaining soluble uranyl nitrate. The washed slag, almost uranium free, was pumped 

to the pits. In addition to residues from thorium processing, Pit 4 also contained drums and rubble 

dumped during plant closure (Ficker 1981).

During the operational period, the total amount of uranium discarded to the raffinate pits was 

measured and reported in the materials balance study (Harris 1986). Table 2-8 summarizes the 

recorded discharges to the raffinate pits.

Table 2-8. Estimated annual discharges to raffinate pits (kg).

a

Fiscal yearb NU DU EU Natural thorium

1958 (c) (c) (c) (c)

1959 (c) (c) (c) (c)

1960 46,193 (c) (c) (c)

1961 12,502 0 0 0

1962 8,831 46 0 0

1963 18,448 0 0 0

1964 35,243 0 0 2,469

1965 13,069 0 2,828 16,170

1966 18,067 0 (20) 26,809

1967 29 0 0 30,750

Total 152,382 46 2,808 76,198

a. From Table 7 in Harris (1986, p. 36). 

b. Fiscal year begins on July 1 of the previous calendar year and ends on June 30 of the calendar year 

corresponding to the designated fiscal year.

c. Discharges to raffinate pits in AEC fiscal years 1958 and 1959 were held in inventory as “potentially 

recoverable.” Beginning in fiscal year 1960, all previous and then current releases to the raffinate pits 

were treated as discharges and removed from the operating inventory as they occurred.

When the raffinate pits were in use, the supernatant solution from Pits 1 through 3 was decanted and 

fed to the plant storm sewer system via buried pipes (Weidner and Boback 1982). Sewage treatment 

effluent added to this flow, and the combined wastewater was discharged off the site into a natural 

streambed. The discharge point, called the process sewer outfall, was within a fenced right-of-way 

that enclosed the stream all the way to the Missouri River. Table 2-9 lists the estimates of discharges 

to the sewer from the materials balance study (Harris 1986). Supernatant from Pit 4 was never 

decanted, which is why Table 2-9 does not indicate thorium discharges to the sewer.
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Table 2-9. Estimated annual discharges to sewer (kg).

a

Fiscal yearb NU DU EU Natural thorium

1958 No data No data No data No data

1959 No data No data No data No data

1960 3,472 No data No data No data

1961 6,461 0 0 0

1962 4,304 0 0 0

1963 6,374 0 0 0

1964 3,239 0 0 0

1965 1,254 0 979 0

1966 1,411 0 0 0

1967 205 0 0 0

Total 26,720 0 979 0

a. From Table 7 in Harris (1986).

b. Fiscal year begins on July 1 of the previous calendar year and ends on June 30 of the calendar year 

corresponding to the designated fiscal year.

While the majority of the thorium and uranium in the raffinate pits and quarry was insoluble, their 

progeny were likely to be more soluble. Therefore, both the WSRP and WSQ pose a potential source 

of groundwater contamination near the WSP site. Ongoing remediation involves active monitoring of 

the groundwater in this region.

2.7.3 Accidents

None of the documented accidents at the WSP site resulted in exceptionally high personnel exposure 

levels (such as a criticality event). Interviews with former WSP employees discussed several 

anecdotal radiological or contamination events, but none of the people interviewed reported that the 

events resulted in high exposures (ORAUT 2009a, 2009b, 2009d, 2009e, 2009f, 2009g).

The Health and Safety Division maintained annual logbooks of forms and memoranda for employees 

with high urinary uranium concentrations. Investigation reports were also included in the logs (for 

Action Level 2 exposures and above). Descriptions of the data forms in Table 2-10 are included to 

demonstrate MCW management of and response to high bioassay results (MCW 1960a, 1961a, 

1962–1965). The Weldon Spring Urinary Uranium Program procedures for 1960 and 1963 provide 

additional information on the bioassay program and use of these forms (MCW 1960b, 1965). 

As examples of the character of accidents, Dupree (1979) cites two accidental exposures of workers 

that occurred during plant operations and were described by Mason during a visit to ORAU in August 

1979. In one instance, a worker overfilled a pot with molten uranyl nitrate solution, which spilled onto 

the floor. A full report of the incident was made (MCW 1961b). In the other case, a worker inhaled 

soluble uranium while trapped in a dust enclosure.

2.8 HEALTH PROTECTION PRACTICES

2.8.1 Operational Period, 1957 to 1966

According to a descriptive report of the MCW contributions between 1942 and 1967 (FleishmanHillard 1967), the design of the WSP “took advantage of the Company’s and the AEC’s accumulated 

wealth of experience concerning the handling of health and contamination problems encountered in 

uranium processing.” The WSP layout was planned with the goal of minimizing the spread of 

contamination. Advanced dust-control systems were used, and onsite health facilities were provided. 

This 1967 document states, “...existing health programs were continued... at the new site, and a 

number of supplemental programs were initiated at the Weldon Spring plant.”
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Table 2-10. Forms for reporting high urinary uranium results. 

Form no. Form title Description

7274 High Exposure Incident Report Includes the following information:

Employee name, department, job, type of exposure (film 

badge or urinary uranium with corresponding units), sample 

date, a description of the incident or occurrence, process or 

equipment to which the high exposure was attributed, and 

follow-up and remedial actions. 

7273 Report of High Urinary Uranium 

Concentration

Report on Action Level Urinary 

Uranium Concentrations 

(Rev. 9-60) 

Multiple employee names with their action level category 

(Action Level 1 to 4), and sample date.

Beginning in September 1960 the following information was 

preprinted on the form:

• Action Level 1 Monday 0.030 to 0.100 mg/L

• Action Level 1 Friday 0.060 to 0.100 mg/L

• Action Level 2 0.100 to 0.200 mg/L

• Action Level 3 0.200 to 0.300 mg/L

• Action Level 4 >0.300 mg/L 

7357 Urinary Uranium Data for Week Weekly summary of the Monday–Friday average urinary 

uranium concentrations by location, number of operators 

participating, percent of employees sampled with results less 

than the action level, and the names of the “peak men” 

(highest exposed employees). 

7463 Urinary Uranium Weekly summary of the Monday–Friday samples by cost 

center, concentration ranges, number of employees in each 

range, names of employees above the Monday or Friday 

limits (>0.030 or 0.060 mg/L, respectively), and the number of 

scheduled and reporting employees. 

Sources: MCW 1960a, 1960b, 1961a, 1962–1965.

The Summary of Health Protection Practices for the Uranium Division (MCW 1965) describes the 

policies and basic principles underlying the health protection program and includes information about 

survey meter checks, film-badging procedures, bioassay procedures, and restrictions on work 

assignments based on previous accumulated exposures. It is likely that this represents a revision of 

the 1955 program (Mason 1955), but it is not clear what or when specific changes were made over 

the intervening years.

Both the 1955 and 1965 documents rely on AEC standards of radiation exposure to the extent that 

health protection decisions were made about worker rotation based on a comparison of monitored 

personnel exposures with these standards for radiation workers (i.e., individuals in controlled areas). 

Table 2-11 summarizes the 1955 document’s list of tolerated cumulative doses in use at MCW. In 

addition, the 1955 document states that the goal was to keep each individual cumulative exposure at 

no greater than one-half of the tolerance when averaged over 3 months. The methods claimed for 

controlling exposure consisted of shielding, semiremote operations, and worker rotation.

Table 2-11. Tolerated dose limits in 1955. 

Type of radiation Tolerated dose limita

Beta 500 mrep/wk, whole body or part

Gamma 300 mR/wk, whole body or part

Beta and gamma 500 mrep/wk, whole body or part

Not specified 1,500 mrep/wk hands and forearms

a. The rep (from “roentgen-equivalent-physical”) is an obsolete unit of 

absorbed dose for types of radiation other than X-rays and gamma 

rays; replaced by the gray.
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Table 2-12 lists the WSP guides for prescribing restricted work so that AEC standards would not be 

exceeded (MCW 1965). Work restriction involved temporary relocation of the affected personnel from 

usual duties until the cumulative average was at an acceptable level.

Table 2-12. Guides for prescribing restricted work based on radiation exposure in 1965 (MCW 1965). 

Type of radiation or 

radioactive material Dose limit

Gamma 3 rem per 3 consecutive calendar months.

10 rem per 12 consecutive calendar months.

5 rem per 12 months averaged over employment beginning 1955.

Beta (skin of whole 

body, thyroid)

10 rem beta + gamma to whole body per 3 consecutive months.

30 rem beta + gamma to whole body per 12 consecutive months.

Beta (hands, forearms, 

feet, ankles)

25 rem beta + gamma to whole body per 3 consecutive months.

75 rem beta + gamma to whole body per 12 consecutive months.

Internal radioactive 

materials (when 

principal effect of the 

material is radiation 

dose to tissues)

50% of the acceptable body burden specified in the recommendations of National 

Bureau of Standards Report 69 (NBS 1959).

Time-weighted exposure concentration averaged over any 4-wk period exceeds 

more than 5 times the quantity in Table 1 of AEC Appendix 0524.

Uranium Average urine concentrations for 3 evenly spaced samples over a 72-hr period 

exceeds 0.15 mg/L and one sample exceeds 0.25 mg/L.

Time-weighted exposure air concentration averaged over 5 consecutive workdays 

exceeds 0.25 mg/m3. 

Concentration in exposure air averaged over a 1-hr exposure exceeds 2.0 mg/m3 (a 

reduction factor of 5 is allowed for a well-fitted mechanical respirator, and a factor 

of 50 for positive pressure respirator).

Uptake by other than inhalation suspected or known, average urine concentrations 

for 3 evenly spaced samples over a 72-hr period exceeds 0.10 mg/L.

2.8.1.1 Badging

According to the Mason (1955) health protection program document, “each employee except office 

females wears [a] combination film badge-security badge.” The stated procedure was to exchange 

these badges biweekly “or more often as indicated.” Dosimeters were placed at selected points 

throughout process areas to serve as integrating area monitors, and routine meter surveys were used 

to detect hot spots and provide information for decisions about protective measures. Data from the 

meter surveys have not been found at this point.

2.8.1.2 Radiological Exposure and Access Control

Workers at WSP had the potential for exposure to airborne radionuclides from uranium or thorium and 

to external radiation from the onsite radioactive materials. Film badges and bioassay were used to 

evaluate actual exposures throughout the operational history. Measures were taken to control 

potential exposures to below AEC standards. According to Mason (1955) these measures involved:

1. Instituting a work permit program (aimed primarily at protecting maintenance workers in 

hazardous areas), which involved establishing time limits and survey meter checks for areas 

with radioactive materials;

2. Conducting investigations and counseling to study causes for exposure trends or unusual 

individual exposures and to educate employees about protective measures;

3. Providing shielding, semiremote operations, and worker rotation to control exposure;
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4. Providing work clothing from the skin out for personnel working in regulated areas (where 

radioactive materials were processed and handled), which could not be worn outside of these 

areas except under cover clothing;

5. Use of respirators as specified by the MCW Health Department; and

6. Instituting a job time-limit program for personnel who worked routinely in areas where the 

exposure rate was known to be above the AEC-based tolerance limits.

MCW (1965) is more general than Mason (1955), but it is reasonable to assume all of the above 

measures were still in place based on language in the 1965 report.

2.8.2 U.S. Department of Defense Control of Chemical Plant, 1967 to 1985

WSP was under control of the Army from 1967 until 1985; it is not a covered facility during those 

years. WSQ and WSRP remained under control of AEC and its successors, and they are covered 

facilities throughout this period. There were no contractors on those sites until 1975. 

During the later years (1975 to 1985) of this period, contractors maintained the integrity of 

embankments of the pits, controlled vegetation, and conducted environmental sampling for 

assessment in relation to the maintenance role. Documentation of the health protection program in 

place for these workers has not been found. However, NLO (1977) states, “no personnel are 

employed or directly assigned to the Weldon Spring site,” and “NLO personnel perform sampling and 

engineering duties on assignment from the Feed Materials Production Center, Fernald, Cincinnati, 

Ohio.” Therefore, exposures to radionuclides at the WSP site were limited because the site was 

essentially undisturbed during this period and the external exposure rate and airborne concentrations 

of radioactivity were minimal in terms of potential short-term exposures to caretakers (NLO 1977).

2.8.3 Remediation Period, 1985 to 2002

During this period, the WSSRAP project management contractor implemented health protection 

practices in compliance with DOE guidelines and regulations on occupational radiation protection 

(DOE 1981, 1986b, 1988b). Because inhalation was recognized as the primary pathway of concern 

at the WSP site in relation to worker exposure during active remediation, the focus of the radiation 

protection program was to control dust emissions and prevent inhalation intakes (DOE 2001b). Intake 

by ingestion was considered possible, but less of a potential dose hazard than inhalation. 

Administrative controls were implemented to minimize ingestion hazards by limiting eating, drinking, 

and smoking in contamination areas; by using personal protective equipment such as coveralls, face 

shields, and gloves; and by meeting monitoring requirements.

Active remediation began in 1993 with the dismantlement of structures at the WSP and the removal of 

bulk wastes at the WSQ. Applicable DOE guidelines and regulations were specified in 10 CFR 

Part 835 at that time. Monitoring to assess internal exposure hazards to remediation workers 

included area monitoring for airborne radionuclides other than radon and thorium, area monitoring for 

radon and thorium, breathing-zone air (BZA) samplers, and bioassay. In work areas where long-lived 

airborne radioactivity concentrations were likely to exceed 2% of the DOE-established limit, BZA 

sampling was conducted on 25% of workers who spent more than 1 hr/d in the area. Bioassay 

requirements included baseline, routine, special, contamination incident, and exit urine samples 

analyzed for uranium for radiological workers who were likely to receive 100 or more mrem/yr 

committed effective dose equivalent (CEDE) and those who declared pregnancy and routinely entered 

controlled areas. The BZA-sampling results were used to determine bioassay participation.
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According to the WSSRAP project management contractor (DOE 2000d), “external dose rates are 

very low at the WSP site. General area external beta dose equivalent rates are at background levels 

(i.e., 0.03-0.05 mrem/hr),” with external gamma dose equivalent rates ranging from background 

(about 60 mrem/yr) to about 113 mrem/yr for continuous exposure in general areas. These exposure 

rates were expected to remain constant for the duration of site remediation. The use of nuclear 

density gauges by remediation workers increased the gamma radiation fields near the equipment 

(3 mrem/hr at 30 cm from the source), so control measures were instituted in these special areas to 

limit worker exposure. Raffinate sludge could produce a contact gamma dose rate in the range of 1 to 

3 mrem/hr (with shallow dose equivalent rates up to 10 mrem/hr). Therefore, most raffinate sludge 

treatment and disposal activities were performed remotely to limit exposure.

2.8.3.1 Badging

According to the January 2000 External Dosimetry Technical Basis Manual (DOE 2000d), “WSSRAP 

has provided personnel dosimetry to radiological workers since October 1986,” just after the 

establishment of the DOE office on the site. According to this manual, only one worker’s monitoring 

results indicated an external effective dose equivalent (EDE) above 100 mrem/yr (the results for this 

worker were 170 mrem EDE in 1994). The highest measured shallow dose equivalent was 

1,450 mrem (in 1994), and all measured extremity dose equivalents were less than this value. The 

DOE-regulated action level of 5,000 mrem annual shallow and extremity dose equivalent was never 

exceeded. As a result, the number of dosimeters issued to personnel was reduced by approximately 

95% due to completion of many of the activities and because future WSSRAP activities were judged 

to be similar to previous activities. The issuance was reduced to include only declared pregnant 

workers who entered controlled areas and those radiological workers likely to receive 100 mrem EDE 

in 1 year from external sources or 5,000 mrem shallow dose equivalent to the skin or any extremity. 

The issuance decision was made by the Worker Protection Supervisor based on area radiation 

monitoring results and estimated exposure times.

2.8.3.2 Radiological Exposure and Access Control

Access to WSP was limited to authorized personnel during the environmental monitoring period by a 

7-ft chain-link cyclone fence topped with three strands of barbed wire. The site was completely 

enclosed by Army-owned areas, and security patrols were provided by the Army to hinder 

unauthorized access (NLO 1977).

During active remediation, measures were taken to control potential internal and external exposures 

according to DOE guidelines, many of which are noted above. Access to areas in which exposures 

could exceed regulatory limits was administratively controlled. The Worker Protection Supervisor (or 

designee) made decisions about access to areas based on area monitoring that evaluated external 

exposure rates as well as air concentrations of radionuclides including radon, thorium, and progeny 

(DOE 2000d, 2001b).

Workplace intake controls included:

• Area decontamination;

• Air-handling units equipped with high-efficiency particulate air (HEPA) filters;

• Dust suppression using water sprays;

• Dust elimination using surface wipe down, HEPA vacuuming, or both; 

• Plastic dust barriers;

• Limiting work area access to essential personnel and equipment;

• Prohibiting eating, drinking, smoking, and chewing tobacco in the work area; and

• Training for hazard recognition before entry in controlled areas.
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Respiratory protection was required when workplace control measures were not possible or 

sufficiently effective, and the need for such was generally assessed when annual intakes of 

radionuclides other than radon, thorium, and progeny were likely to result in dose equivalents 

exceeding 100 mrem CEDE, or when intakes of radon, thorium, and progeny were likely to result in 

dose equivalents above 500 mrem CEDE.

2.9 JOB TITLES AND LOCATIONS DURING OPERATIONAL PERIOD

Table 2-13 provides a correlation of the job titles and locations for the plant during the operational 

phase. This information is useful in identifying work locations of a worker if the job title is known. This 

information is from a document titled History of MCW-Uranium Division (MAL-UD) that accompanied a 

memorandum that describes a visit to Oak Ridge by Mont Mason (Dupree 1979), who was head of 

Health and Safety for MCW for a number of years.

Table 2-13. Partial list of job titles and locations during operational period. 

Job title Job type Job location or buildinga

103 DX men Porter Refinery – Digestion and Denitration (103)

105 DX men Porter Refinery – Extraction (105)

201 DX men Porter Green Salt Plant (201)

201 Production Office Porter Porter Green Salt Plant (201)

301 DX men Porter Metals Building (301)

408 Porter Porter Maintenance (408)

Accountability Lab Technical Analytical Laboratory (407)

Assistant Foreman Supervisory Stores (408)

Assistant Superintendent Supervisory Green Salt Plant (201)

Auxiliary Dissolving Operator Operator Refinery – Digestion and Denitration (103)

Blending Operator Operator Metals Building (301) – Conversion

Bomb Cooling Operator Operator Metals Building (301) – Conversion

Bomb Unloading Operator Operator Metals Building (301) – Conversion

Capping & Tamping Operator Operator Metals Building (301) – Conversion 

Carpenter Carpenter Maintenance Department (408)

Casting Operator Operator Metallurgical Pilot Plant (404)

Ceramics Operator Operator Metallurgical Pilot Plant (404)

Clerical and Steno Clerical Stores (408)

Clerical and Steno Clerical Production Control office

Control Technical Analytical Laboratory (407?)

Decontamination Room DX Porter Various process buildings ?

Digester Operator Operator Refinery – Digestion and Denitration (103)

Dingot Chipping Operator Operator Metals Building (301) – Conversion

Dishwasher Labor Analytical Laboratory (407)

Draftsmen Draftsmen Engineering 

Electrician Electrician Maintenance Department

Employee Benefits officer Clerical Industrial Relations

Engineer Engineer Maintenance Department (408)

Engineer Engineer Engineering 

Extrusion Press Operator Operator Metals Building (301) – Fabrication and Extrusion

Feed Operator Operator Refinery – Digestion and Denitration (103)

Filling Operator Operator Metals Building (301) – Conversion

Fluoride Chemistry Technician Technical Research Laboratory

Foreman Supervisory Stores (408)

Foreman Supervisory Warehouse (406)

Foreman Supervisory Sampling Plant (101)

Foreman Supervisory Maintenance Department (408)

Foreman Supervisory Metallurgical Pilot Plant (404)

Foreman Supervisory Wet (Chemical?) Pilot Plant (403)
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Job title Job type Job location or buildinga

Forge Press Operator Operator Metallurgical Pilot Plant (404)

Furnace and Saw Operator Operator Metallurgical Pilot Plant (404)

Furnace Operator Operator Green Salt Plant (201)

Furnace Operator Operator Metals Building (301) – Conversion

General Foreman Supervisory Refinery (103-105)

General Foreman Supervisory Green Salt Plant (201)

General Foreman Supervisory Metals Building (301)

General Foreman Supervisory Maintenance Department (408)

General Labor Labor Boiler House (401)

General Labor Labor Water Plant (429?)

General Office Clerical Health Department (410)

General Office Clerical Industrial Engineering 

General Office Clerical Engineering

General Office Clerical Industrial Relations

General Office Clerical Safety and Fire

General Office Clerical Accounting

General Office Clerical Purchasing

General Office Clerical Administrative Services (409)

General Office Clerical Payroll (409?)

General Office Clerical Tabulating Office

General Office Clerical Research Laboratory (407?)

General Office Clerical Production Technical Department

Guard Plant protection Plant Wide

Guard Captain Plant protection Plant Wide

Guard Lieutenant Plant protection Plant Wide

HF Operator Operator Green Salt Plant (201)

Industrial Hygiene Industrial Hygiene Health Department (410)

Inspectors Inspector Safety and Fire 

Jolter Operator Operator Metals Building (301) – Conversion

Laborer Laborer Maintenance Department (408)

Lathe Operator Operator Metals Building (301) – Fabrication and Extrusion

Lead Operator Operator Metallurgical Pilot Plant (404)

Lid Chipping Operator Operator Metals Building (301) – Conversion

Locker Room Porters Porter Services Building (410?)

Machine Maintenance Laborer Maintenance Department (408)

Magnesium Building Operator Operator Metals Building (301) – Conversion

Maintenance Clerks Clerical Maintenance Department (408)

Messenger Messenger Administrative Services

Metallurgical Technician Technical Research Laboratory

Methods Development Technical Analytical Laboratory

Misc. Digestion Operator Operator Refinery – Digestion and Denitration (103)

Motor and Equipment Tagger Labor Accounting (409?)

Nitric Acid Operator Operator Refinery – Digestion and Denitration (103)

NOK Operator Operator Refinery – Nitric Acid in Hexane (NAH)

Office and Steno Clerical Analytical Laboratory (407)

Oiler Laborer Maintenance Department (408)

Operator Operator Wet (Chemical?) Pilot Plant (403)

Operators Operator Sampling Plant (101)

Packaging Operator Operator Refinery – Digestion and Denitration (103)

Packaging Operator Operator Green Salt Plant (201)

Painter Painter Maintenance Department (408)

Pipe Maintenance Laborer Maintenance Department (408)

Plant Porter Porter Plant-wide

Pot Room Operator Operator Refinery – Digestion and Denitration (103)

Production Clerk Clerical Sampling Plant (101)
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Job title Job type Job location or buildinga

Production Clerk Clerical Refinery (103-105)

Production Clerk Clerical Green Salt Plant (201)

Production Clerk Clerical Metals Building (301)

Production Machinist Operator Metallurgical Pilot Plant (404)

Production Operator Operator Metallurgical Pilot Plant (404)

Pulse Column Operator Operator Refinery (105/108)– Nitric Acid in Hexane (NAH)

Pumper Decanter Operator Operator Refinery (105/108)– Nitric Acid in Hexane (NAH)

Raffinate Operator Operator Refinery (103) – Digestion and Denitration 

Recovery Operator Operator Refinery (103) – Digestion and Denitration 

Residue Operator Operator Metallurgical Pilot Plant (404)

Rigger Rigger Maintenance Department (408)

Sampling plant DX men Porter Sample plant

Saw Operator Operator Metals Building (301) – Fabrication and Extrusion

Shift Assistant Foreman Supervisory Refinery

Shift Foreman Supervisory Refinery

Shift Foreman Supervisory Green Salt Plant – 201

Shift Foreman Supervisory Metals Building (301)

Shift Foreman Supervisory Metallurgical Pilot Plant (404)

Shift Foreman Supervisory Wet (Chemical?) Pilot Plant (403)

Slag Building Operator Operator Metals Building (301) – Conversion

Special Analysis Technical Analytical Laboratory

Special Techniques Technician Technical Research Laboratory

Specification Testing Technical Analytical Laboratory

Spectrographic Technical Analytical Laboratory

Stenographer Clerical Maintenance Department (408)

Storekeeper Stores Stores (408)

Stripper Operator Operator Refinery (105/108) – Nitric Acid in Hexane (NAH)

Sump Operator Operator Metals Building (301) – Fabrication and Extrusion

Superintendent Supervisory Refinery (103-105)

Superintendent Supervisory Metals Building (301)

Superintendent Supervisory Maintenance Department (408)

Superintendent Supervisory Production Technical Department

Supervisor Supervisory Production Control office

Technical Technical Metallurgical Pilot Plant (404)

Technical Technical Wet (Chemical?) Pilot Plant (403)

Technical Services Staff Technical Production Technical Department–Sampling Plant (101)

Technical Services Staff Technical Production Technical Department–Refinery

Technical Services Staff Technical Production Technical Department–Green Salt Plant 201

Technical Services Staff Technical Production Technical Department–Metals Building (301)

Tinner Laborer Maintenance Department (408)

Utility Operator Operator Green Salt Plant (201)

Vacuum Techniques 

Technician

Technical Research Laboratory (407)

Warehouse Yard Operator Operator Sampling Plant (101)

Warehouse Yard Operator Operator Refinery (103-105)

Warehouse Yard Operator Operator Green Salt Plant – 201

Warehouse Yard Operator Operator Metals Building (301)

Warehouse Yard Operator Operator Various

Welder Welder Maintenance Department (408)

Wet Chemistry Technician Technical Research Laboratory (407)

a. A question mark denotes disagreement in the various documents that describe jobs or locations.
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2.10 ATTRIBUTIONS AND ANNOTATIONS

All information requiring identification was addressed via references integrated into the reference 

section of this document.
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REFERENCES

AEC (U.S. Atomic Energy Commission), 1958, Expansion Program At St. Louis Area, TID-5886, St. 

Louis, Missouri, December. [SRDB Ref ID: 11798]

Army (U.S. Department of the Army), 1976, Assessment of Weldon Spring Chemical Plant in 

St. Charles, County, Missouri, Office of the Deputy Assistant Project Manager for Chemical 

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GLOSSARY

curie (Ci)

Traditional unit of radioactivity equal to 37 billion (3.7 × 1010) becquerels, which is 

approximately equal to the activity of 1 gram of pure 226Ra.

dose equivalent

In units of rem or sievert, product of absorbed dose in tissue multiplied by a weighting factor 

and sometimes by other modifying factors to account for the potential for a biological effect 

from the absorbed dose

dosimeter

Device that measures the quantity of received radiation, usually a holder with radiationabsorbing filters and radiation-sensitive inserts packaged to provide a record of absorbed dose 

received by an individual. 

dosimetry

Measurement and calculation of internal and external radiation doses. 

dosimetry system

System for assessment of received radiation dose. This includes the fabrication, assignment, 

and processing of external dosimeters, and/or the collection and analysis of bioassay samples, 

and the interpretation and documentation of the results. 

exposure

(1) In general, the act of being exposed to ionizing radiation. (2) Measure of the ionization 

produced by X- and gamma-ray photons in air in units of roentgens.

extremities

Portion of the arm from and including the elbow through the fingertips and the portion of the 

leg from and including the knee and patella through the toes.

film

(1) In the context of external dosimetry, radiation-sensitive photographic film in a light-tight 

wrapping. (2) X-ray film.

gamma radiation 

Electromagnetic radiation (photons) of short wavelength and high energy (10 kiloelectron-volts 

to 9 megaelectron-volts) that originates in atomic nuclei and accompanies many nuclear 

reactions (e.g., fission, radioactive decay, and neutron capture). Gamma photons are identical 

to X-ray photons of high energy; the difference is that X-rays do not originate in the nucleus.

gamma ray, particle, or photon

See gamma radiation. 

hydrofluorination

Chemical conversion to a form containing fluorine.

isotope

One of two or more atoms of a particular element that have the same number of protons 

(atomic number) but different numbers of neutrons in their nuclei (e.g., 234U, 235U, and 238U). 

Isotopes have very nearly the same chemical properties.
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neutron

Basic nucleic particle that is electrically neutral with mass slightly greater than that of a proton. 

There are neutrons in the nuclei of every atom heavier than normal hydrogen.

nuclide

Stable or unstable isotope of any element. Nuclide relates to the atomic mass, which is the 

sum of the number of protons and neutrons in the nucleus of an atom. A radionuclide is an 

unstable nuclide.

photon

Quantum of electromagnetic energy generally regarded as a discrete particle having zero rest 

mass, no electric charge, and an indefinitely long lifetime. The entire range of electromagnetic 

radiation that extends in frequency from 1023 cycles per second (hertz) to 0 hertz. 

radiation

Subatomic particles and electromagnetic rays (photons) with kinetic energy that interact with 

matter through various mechanisms that involve energy transfer.

radioactivity

Property possessed by some elements (e.g., uranium) or isotopes (e.g., 14C) of spontaneously 

emitting energetic particles (electrons or alpha particles) by the disintegration of their atomic 

nuclei. 

radionuclide

Radioactive nuclide. 

raffinate

Waste from uranium or thorium extraction as well as solids from the neutralization of this 

waste. 

rem

Traditional unit of radiation dose equivalent that indicates the biological damage caused by 

radiation equivalent to that caused by 1 rad of high-penetration X-rays multiplied by a quality 

factor. The sievert is the International System unit; 1 rem equals 0.01 sievert. The word 

derives from roentgen equivalent in man; rem is also the plural.

roentgen 

Unit of photon (gamma or X-ray) exposure for which the resultant ionization liberates a positive 

or negative charge equal to 2.58 × 10-4 coulombs per kilogram (or 1 electrostatic unit of 

electricity per cubic centimeter) of dry air at 0 degrees Celsius and standard atmospheric 

pressure. An exposure of 1 roentgen is approximately equivalent to an absorbed dose of 1 

rad in soft tissue for higher energy photons (generally greater than 100 kiloelectron-volts).

shielding

Material or obstruction that absorbs ionizing radiation and tends to protect personnel or 

materials from radiation.

U.S. Atomic Energy Commission (AEC)

Federal agency created in 1946 to assume the responsibilities of the Manhattan Engineer 

District (nuclear weapons) and to manage the development, use, and control of nuclear energy 

for military and civilian applications. The U.S. Energy Research and Development 

Administration and the U.S. Nuclear Regulatory Commission assumed separate duties from 
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the AEC in 1974. The U.S. Department of Energy succeeded the U.S. Energy Research and 

Development Administration in 1979.

X-ray radiation

Electromagnetic radiation (photons) produced by bombardment of atoms by accelerated 

particles. X-rays are produced by various mechanisms including bremsstrahlung and electron 

shell transitions within atoms (characteristic X-rays). Once formed, there is no difference 

between X-rays and gamma rays, but gamma photons originate inside the nucleus of an atom.