ORAU TEAM

Dose Reconstruction

Project for NIOSH

Oak Ridge Associated Universities I Dade Moeller I MJW Technical Services

Page 1 of 44

DOE Review Release 05/30/2013

Document Title:

Weldon Spring Plant – Site Description

Document Number: ORAUT-TKBS-0028-2 

Revision: 01

Effective Date: 05/21/2013

Type of Document: TBD

Supersedes: Revision 00

Subject Expert(s): Samuel L. Chu

Approval: Signature on File Approval Date: 05/17/2013

David P. Harrison, Document Owner

Concurrence: Signature on File Concurrence Date: 05/15/2013

John M. Byrne, Objective 1 Manager

Concurrence: Signature on File Concurrence Date: 05/15/2013

Edward F. Maher, Objective 3 Manager

Concurrence: Vickie S. Short Signature on File for Concurrence Date: 05/15/2013

Kate Kimpan, Project Director

Approval: Signature on File Approval Date: 05/21/2013

Stuart L. Hinnefeld, Director DCAS 

New Total Rewrite Revision Page Change

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

REVISION AND DISCARD / DESTROY ALL COPIES OF THE PRIOR REVISION.
Document No. ORAUT-TKBS-0028-2 Revision No. 01 Effective Date: 05/21/2013 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.
Document No. ORAUT-TKBS-0028-2 Revision No. 01 Effective Date: 05/21/2013 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 History ............................................................................................................8

2.3 Site Acquisition and Development (1954 to 1957)....................................................................11

2.4 Plant Operations (1957 to 1966) ...............................................................................................11

2.4.1 Materials Processed During Plant Operations ............................................................. 11

2.4.2 Plant Processes and Operations.................................................................................. 14

2.4.2.1 Uranium Concentrate Sampling .....................................................................14

2.4.2.2 UO3 Production...............................................................................................14

2.4.2.3 UF4 Production ...............................................................................................16

2.4.2.4 UF4 to Metal Conversion.................................................................................16

2.4.2.5 Products Manufacturing .................................................................................17

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

2.4.2.7 Analytical and Research Laboratories............................................................18

2.4.2.8 Pilot Plants .....................................................................................................19

2.4.2.9 Raffinate Pits ..................................................................................................19

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

2.4.3 Plant Operations and Radioactive Material of Concern Summary............................... 20

2.5 Department of Defense Control (1967 to 1985)........................................................................20

2.6 Monitoring and Maintenance (1975 to 1985) ............................................................................24

2.7 Site Remediation.......................................................................................................................24

2.8 Releases to the Outdoor Environment......................................................................................25

2.8.1 Airborne Emissions ...................................................................................................... 25

2.8.2 Waterborne Emissions ................................................................................................. 26

2.8.3 Accidents...................................................................................................................... 28

2.9 Health Protection Practices.......................................................................................................29

2.9.1 Operational Period (1957 to 1966) ............................................................................... 29

2.9.1.1 Badging ..........................................................................................................30

2.9.1.2 Radiological Exposure and Access Control....................................................30

2.9.2 Postoperational Period (1975 to Present).................................................................... 31

2.9.2.1 Badging (Postoperational)..............................................................................32

2.9.2.2 Radiological Exposure and Access Control....................................................32

2.10 Suplemental Information...........................................................................................................33

2.10.1 Job Titles and Locations During Operational Phase .................................................... 33

2.11 Attributions and Annotations .....................................................................................................36
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References ...........................................................................................................................................37

Glossary................................................................................................................................................43

LIST OF TABLES

TABLE TITLE PAGE

2-1 Annual uranium and thorium mass receipts..............................................................................12

2-2 Thoron and isotopic daughters ................................................................................................. 14

2-3 Chronological summary of thorium operations .........................................................................18

2-4 Description of WSP buildings and operations...........................................................................21

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

2-6 Location and height of stacks at the WSCP..............................................................................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 ......................................................................28

2-11 Tolerated dose limits in 1955....................................................................................................30

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 phase .................................................33

LIST OF FIGURES

FIGURE TITLE PAGE

2-1 Weldon Spring Plant location......................................................................................................9

2-2 Weldon Spring Plant site...........................................................................................................10

2-3 Sampling plant flow diagram.....................................................................................................15

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

2-5 Reduction and hydrofluorination process..................................................................................16

2-6 UF4 conversion to uranium metal..............................................................................................17
Document No. ORAUT-TKBS-0028-2 Revision No. 01 Effective Date: 05/21/2013 Page 5 of 44

ACRONYMS AND ABBREVIATIONS

ac acre 

AEC U.S. Atomic Energy Commission

BZA breathing-zone air

CEDE committed effective dose equivalent

CFR Code of Federal Regulations

Ci curie 

cm centimeter

CSS chemical stabilization and solidification

DOE U.S. Department of Energy

DOL U.S. Department of Labor

EDE effective dose equivalent

EEOICPA Energy Employees Occupational Illness Compensation Program Act of 2000

EPA U.S. Environmental Protection Agency

ft foot

gal gallon

HEPA high-efficiency particulate air

hr hour

kg kilogram

km kilometer

L liter

m meter

MCW Mallinckrodt Chemical Works

mg milligram

mR milliroentgen

mrem millirem

NIOSH National Institute for Occupational Safety and Health

NLCO National Lead Company of Ohio

NPL National Priorities List

ORAU Oak Ridge Associated Universities

POC probability of causation

ppb parts per billion

RI/FS remedial investigation/feasibility study

SWTP Site Water Treatment Plant

TNT trinitrotoluene (1940s explosives production), thorium nitrate tetrahydrate (mid-1960s 

thorium operations)

TSA Temporary Storage Area
Document No. ORAUT-TKBS-0028-2 Revision No. 01 Effective Date: 05/21/2013 Page 6 of 44

WSCP Weldon Spring Chemical Plant

WSP Weldon Spring Plant

WSQ Weldon Spring Quarry

WSRP Weldon Spring Raffinate Pits

WSSRAP Weldon Spring Site Remedial Action Project

U.S.C. United States Code

yd yard

yr year

§ section or sections
Document No. ORAUT-TKBS-0028-2 Revision No. 01 Effective Date: 05/21/2013 Page 7 of 44

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 sites or categories of sites. They will be revised in the event 

additional relevant information is obtained about the affected site(s). These documents may be used 

to assist NIOSH staff in the completion of the individual work required for each dose reconstruction.

In this document the word “facility” is used as a general term for an area, building, or group of 

buildings that served a specific purpose at a site. It does not necessarily connote an “atomic weapons 

employer facility” or a “Department of Energy [DOE] facility” as defined in the Energy Employees 

Occupational Illness Compensation Program Act [EEOICPA; 42 U.S.C. § 7384l(5) and (12)]. 

EEOICPA defines a DOE facility 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 Department of Energy (except for buildings, structures, premises, 

grounds, or operations ... pertaining to the Naval Nuclear Propulsion Program)” [42 U.S.C. § 

7384l(12)]. Accordingly, except for the exclusion for the Naval Nuclear Propulsion Program noted 

above, any facility that performs or performed DOE operations of any nature whatsoever is a DOE 

facility encompassed by EEOICPA.

For employees of DOE or its contractors with cancer, the DOE facility definition only determines 

eligibility for a dose reconstruction, which is a prerequisite to a compensation decision (except for 

members of the Special Exposure Cohort). The compensation decision for cancer claimants is based 

on a section of the statute entitled “Exposure in the Performance of Duty.” That provision [42 U.S.C. § 

7384n(b)] says that an individual with cancer “shall be determined to have sustained that cancer in the 

performance of duty for purposes of the compensation program if, and only if, the cancer ... was at 

least as likely as not related to employment at the facility [where the employee worked], as 

determined in accordance with the POC [probability of causation1

] guidelines established under 

subsection (c) ...” [42 U.S.C. § 7384n(b)]. Neither the statute nor the probability of causation 

guidelines (nor the dose reconstruction regulation, 42 C.F.R. Pt. 82) restrict the “performance of duty” 

referred to in 42 U S. C. § 7384n(b) to nuclear weapons work (NIOSH 2010).

The statute also includes a definition of a DOE facility that excludes “buildings, structures, premises, 

grounds, or operations covered by Executive Order No. 12344, dated February 1, 1982 (42 U.S.C. 

7158 note), pertaining to the Naval Nuclear Propulsion Program” [42 U.S.C. § 7384l(12)]. While this 

definition excludes Naval Nuclear Propulsion Facilities from being covered under the Act, the section 

of EEOICPA that deals with the compensation decision for covered employees with cancer [i.e., 42 

U.S.C. § 7384n(b), entitled “Exposure in the Performance of Duty”] does not contain such an 

exclusion. Therefore, the statute requires NIOSH to include all occupationally-derived radiation 

exposures at covered facilities in its dose reconstructions for employees at DOE facilities, including 

radiation exposures related to the Naval Nuclear Propulsion Program. As a result, all internal and 

external occupational radiation exposures are considered valid for inclusion in a dose reconstruction. 

No efforts are made to determine the eligibility of any fraction of total measured exposure for inclusion 

in dose reconstruction. NIOSH, however, does not consider the following exposures to be 

occupationally derived (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

 

1 The U.S. Department of Labor (DOL) is ultimately responsible under the EEOICPA for determining the POC.
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2.1.1 Purpose

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

Spring (WSP) facilities, processes, operations and their associated nuclear materials of potential 

concern. The WSP includes the Weldon Spring Chemical Plant (WSCP), the Weldon Spring Quarry 

(WSQ), and the Weldon Spring Raffinate Pits (WSRP). The information in this document provides 

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

support the dose reconstruction efforts. WSP operations played an important role in the U.S. 

development of nuclear power and nuclear weapons. Operations focused on processing of 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 plant operations from 1957 to 1966. Section 2.5 

covers 1967 to 1985 when the WSCP was under the control of the U.S. Department of Defense, and 

Section 2.6 covers the monitoring and maintenance period that began in 1975 and ended in 1985. 

Section 2.7 discusses site remediation that occurred after that from 1985 to 2002. Section 2.8

discusses releases to the outdoor environment, and Section 2.9 discusses health protection at WSP 

during all periods. Section 2.10 provides supplemental information on job titles and locations during 

the operational period. Section 2.11 is the Attributions and Annotations section.

2.2 SITE LOCATION AND HISTORY

The 220-ac WSCP site is about 2 mi southwest of the community of Weldon Spring and the junction 

of Missouri State Route 94 and U.S. Highway 40/61 (Figure 2-1). The site contained 44 buildings and 

support structures as well as remnants of a railroad system, four raffinate pits, and two small ponds. 

An 8.7-ac limestone quarry (WSQ), used in part to deposit radioactive wastes from the WSCP, is part 

of the WSP site, although it is about 4 mi southwest of the plant. Figure 2-2 shows the WSCP and 

raffinate pits.
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Figure 2-1. Weldon Spring Plant location. 
Document No. ORAUT-TKBS-0028-2 Revision No. 01 Effective Date: 05/21/2013 Page 10 of 44

Figure 2-2. Weldon Spring Plant site (adapted from several 

documents).

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

WSCP 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 (TNT) 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.

In 1956, approximately 220 ac of the former Ordnance Works were transferred to the U.S. Atomic 

Energy Commission (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; the date of initial operation was June of 1957 (MCW 

1957). Nuclear materials in the form of natural uranium concentrates were being stored at the site 

prior to the start of operations, but “since they were not processed, they did not engender operational 

losses” (DOE 1986a). Thus, it is reasonable to assume exposures prior to operational startup were 

negligible. This is the WSCP referred to in this document. The raffinate pits were originally part of the 

WSCP, but are referred to separately in this document as the Weldon Spring Raffinate Pits (WSRP) 
Document No. ORAUT-TKBS-0028-2 Revision No. 01 Effective Date: 05/21/2013 Page 11 of 44

because they were managed separately from the other area of the WSCP in the post-operational 

period. In 1958, a 9-ac quarry site was transferred to the AEC and is referred to as the Weldon 

Spring Quarry (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 WSCP was returned to U.S. Army control for construction of an herbicide 

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

Decontamination of the transferred WSCP facilities was attempted between 1968 and 1970, but 

abandoned because of cost. The U.S. Department of Energy (DOE) regained responsibility for the 

WSCP in 1985 and began site characterization and remediation in 1985. The U.S. Army never 

completed or produced any herbicides during this period. The quarry was placed on the U.S. 

Environmental Protection Agency’s (EPA) National Priorities List (NPL) in 1987, and the listing was 

expanded to include the WSCP and associated waste storage areas in 1989. 

Before remediation, four periods of WSP site history can be identified:

• Plant acquisition and development (1954 to 1957)

• Operations (1957 to 1966) 

• Department of Defense Control (1967 to 1985)

• Monitoring and Maintenance (1975 to 1985). 

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

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

2.3 SITE ACQUISITION AND DEVELOPMENT (1954 TO 1957)

In August 1956, Congress officially 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 WSCP 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 initially 

designed specifically to process uranium mill concentrates (yellow cake) produced elsewhere in the 

United States and Canada. These materials were shipped to the WSP site for sampling to determine 

payment. Fractions of the total mill concentrates were processed through chemical treatment 

operations. Other fractions, after sampling, were shipped to other DOE facilities for further 

processing.

2.4 PLANT OPERATIONS (1957 TO 1966) 

2.4.1 Materials Processed During Plant Operations

The WSCP was operated for AEC by the Uranium Division of MCW from 1957 to 1966. The WSCP 

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 (DOE 1986a), which summarized the types and quantities of nuclear 

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

materials were processed during the operational period of WSP: (1) natural uranium, (2) depleted 

uranium, (3) slightly enriched uranium, and (4) natural thorium. The great majority of material 

processed at WSP was natural uranium (approximately 98% of the total mass of processed 
Document No. ORAUT-TKBS-0028-2 Revision No. 01 Effective Date: 05/21/2013 Page 12 of 44

materials). An average of 1.2 × 107 kg (1.4 × 104 tons) of uranium-containing material was processed 

per year (DOE 1986a). Natural uranium processing accounted for more than 98% of the nuclear 

materials throughput. Total material balance closures (i.e., percent of material accounted for) for 

natural uranium, depleted uranium, and slightly enriched uranium for the 10 years of plant operations 

were 99.94%, essentially 100%, and 99.27%, respectively. An average of 3.1 × 105 kg (350 tons) of 

natural thorium was processed per year during 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) (DOE 1986a).

Fiscal yeara 

Natural uranium

material

Depleted uranium 

material

Slightly enriched 

uranium material

Natural thorium 

material

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.

The following paragraphs describe the use of these materials at the WSCP:

Natural Uranium: Natural uranium 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 the site. Processing of natural 

uranium was a continuous operation during the life of the plant.

Uranium concentrates primarily handled at Weldon Spring Plant facility consisted of 234U, 235U, and 

238U in their natural abundances with very low concentrations of decay products. Historical 

documents report that Weldon Spring did not receive the high-quality pitchblende ores that were 

processed at the Mallinckrodt Destrehan Street facility (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 (Personal Communication 2009c; Personal Communication, 2009g; Personal 

Communication, 2009h).

Decay products and other impurities including natural thorium (e.g., 232Th and 228Th) were present in 

the uranium ore concentrates processed at the Weldon Spring Plant. These materials and their 

associated quantities were considered a minor hazard compared to the uranium itself. The Weldon 

Spring Historical Dose Estimate (Meshkov et al. 1986) is a historical offsite dose estimate study that 

estimates the activities of 230Th and 226Ra in yellowcake to be 5% and 1% of 238U activity, respectively. 

However, specific isotopic characterization of raffinates at Weldon Spring indicates that the uranium 

mill processes that produced the yellowcake concentrates that was used at 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 (2013b). The shorter lived decay products, 

210Pb and 210Po, for which no raffinate measurements were made should be assumed to be present at 

the same activity as the 226Ra in raffinate pits. As indicated above, there is no suggestion in the 
Document No. ORAUT-TKBS-0028-2 Revision No. 01 Effective Date: 05/21/2013 Page 13 of 44

historical records that the Weldon Spring Plant ever processed the high-activity pitchblende, which 

contained significant concentrations of radium. The ore concentrates processed at Weldon Spring 

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 isotope below its natural isotopic abundance ratio was 

received as metal and various intermediate chemical forms, and processed on an intermittent basis. 

This form of uranium was used primarily in product development activities, flow-sheet improvements 

and confined primarily to pilot plant activities.

Slightly 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 received 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 natural uranium, primarily because of the heterogeneous nature of receipts.

Some post-1961 shipments of slightly enriched uranium that came from the Fernald Site could have 

included some quantities of recycled uranium (RU). In 1999, DOE initiated the complex-wide 

Recycled Uranium Mass Balance Project (DOE 2000a), which identified WSP as a site that likely 

received recycled uranium in relatively small quantities of materials after 1961. The significance of 

these receipts of recycled uranium is that this material contains trace amounts of residual transuranic 

elements (including plutonium and neptunium), fission products (such as technetium), and reactorproduced uranium isotopes (such as 236U) (DOE 2000a). Site records do not include the level of detail 

needed for an accurate estimate of the amount of recycled material received and processed at WSP. 

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 natural uranium are not known. Due to the lack of information about RU

quantities, the May 15, 2000, DOE report addressing WSP RU (DOE 2000a) assumes that all 

uranium receipts after 1961 (71,413,060 kg) were recycled, which is a large overestimate of the actual 

quantity because the same document reports that the majority of material processed through WSP 

was natural uranium. The levels of the RU contaminants at Weldon Spring (239Pu, 237Np, and 99Tc) 

are determined from the Technical Basis Document for the Fernald Environmental Management 

Project (FEMP) – Occupational Internal Dose (ORAUT 2004): 100 ppb 239Pu, 3,500 ppb 237Np, and 

9,000 ppb 99Tc. 1 ppb-Pu/U is 1 × 10-9 gm-Pu/gm-U.

Natural Thorium: Natural thorium was typically received in either a nitrate or an oxide form and 

processed on an intermittent batch basis in the refinery and oxide production/firing systems. Only a 

limited area of the WSCP (refinery and pilot plants) was exposed to the material. In addition, Dupree 

(1979) stated that approximately 3.6 × 105 kg (400 tons) of “impure thorium nitrate and enriched 

uranium” were processed starting in 1965.

Thoron is the second daughter product of 228Th, and after a couple of weeks, following 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 daughter product of the long-lived 232Th, and is generally in 40% to 

65% equilibrium for materials processed at the WSCP. The degree of equilibrium is dependent upon 

both the decay of 228Th (without replenishment from the 5.7 year half-life of 228Ra) after removal of the 

thorium daughters 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 

WSCP and the associated waste storage locations. The thoron, with its subsequent daughter 

products, would act as 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 daughters.
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Table 2-2. Thoron and isotopic daughters. 

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 b -

Lead-212 10.64 hr 15476 7.8 1.21E+5

Bismuth-212 60.6 min 1469 7.8 0.12E+5

Polonium-212 0.3 μsec - b -

Thallium-208 3 min 73 - -

Total 1.33E+5

a. Potential alpha-energy concentration (PAEC). 

b. The alpha energy is emitted only by Po-216 and essentially Bi-212. In reality Bi-212 emits an alpha 

only 36% of the time but the other 64% of the time it emits a beta then an alpha almost immediately 

through the decay of Po-212 (304 nsec 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). Since Po-216 ultimately decays by two 

alphas (Po-216 and Bi-212) the alpha energy released per Po-216 atom is 14.6 MeV. Pb-212 and Bi212 both decay with an effective alpha energy of 7.8 MeV.

2.4.2 Plant Processes and Operations

The WSCP’s main activity was to convert uranium concentrate to uranium trioxide (UO3), uranium 

tetrafluoride (UF4), and uranium metal. The material received at the plant 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 sampling—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.

2.4.2.2 UO3 Production

UO3 (sometimes known as 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 generated in 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 off gasses containing radon and nitrogen oxides from the digestion process were sent to the 
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Figure 2-3. Sampling plant flow diagram (adapted from US Army 1976).

Figure 2-4. Digestion, purification, and denitration (adapted from US Army 1976).

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

estimated as being between 12 and 34 Ci/yr based on throughput (Meshkov et al. 1986, p. 48).
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2.4.2.3 UF4 Production

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 used to 

produce UF4. Hydrogen gas reduced UO3 to uranium dioxide (UO2). 

Figure 2-5. Reduction and hydrofluorination process (adapted from US 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, 

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 UF4 to Metal Conversion

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 refractory-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. Within 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 in order to recover the uranium from scrap and to convert them to U3O8. One 

standard dust collector was used for the dusty discharge, mostly U3O8, produced in this operation.
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Figure 2-6. UF4 conversion to uranium metal (adapted from US 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, heat 

treated, 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-inch lengths. The rough cores 

were then treated at 950°F in a vacuum furnace to remove hydrogen gas from the metal. Degassed 

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 a nitrate or an oxide form and processed on an intermittent 

basis in the refinery and oxide production/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(DOE 1986a). 

An average of 1.2 x 107 kg (1.4 × 104 tons) of uranium containing material was processed per year 

(DOE 1986a). Natural uranium processing accounted for more than 97% of the nuclear materials 

throughput. Total material balance closures (i.e., percent of material accounted for) for natural 

uranium, depleted uranium, and slightly enriched uranium for the 10 years of plant operations were 

99.94%, essentially 100%, and 99.27%, respectively. An average of 3.1 x 105 kg (350 T) of natural 

thorium was processed per year during 1964 through 1966, with an associated total material balance 
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closure of 98.52%. MCW (1958–1966) summarized operations with thorium as shown in Table 2-3. 

Thorium process wastes were deposited in Raffinate Pit 4. In the table below, “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

301 Oct–Dec

Denitration of TNT crystals & sol 

drying-hand unloading

103 Nov–Dec May–Aug

Denitration of TNT crystals & sol 

drying-vacuum uploading

103 Sep–Dec

Denitration of TNT liquor & sol 

drying-vacuum uploading

103 Jan–Jul

Denitration by fluid bed-product 

packaged in drums

403 May–Jul

Denitration by fluid bed-liquor feed & 

sol product

403 Aug–Dec Jan; Jun–Sep

Denitration of TNT liquor-scoop & pail 

transfer to sol tank

103 Oct–Nov

Sol drying-vacuum uploading 103 Aug–Dec Jan; Jun–Sep

ThO2 high firing-recast furnace 301 Nov–Dec May–Sep

ThO2 high firing-billet heaters 301 Oct–Dec Jan–Dec Jan; Jun–Sep

ThO2 product packaging 403 Nov–Dec May–Jul; Sep–Dec Jan–Sep

103 Aug

301 Oct–Dec Jan; Jun–Sep

Rotary kiln calcining of sump cake 301 Apr–Jul

Digest feed repackaging 101 Apr–Aug

Scrap digestion & raffinate disposal 103 May–Sep

Extraction 105 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 in 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 

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.
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2.4.2.8 Pilot Plants

Buildings 403 and 404 housed the Chemical and Metallurgical Pilot Plants, respectively. The 

chemical and metallurgical pilot plants had development facilities on a scale intermediate between 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. Also studied in the chemical pilot plant was 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 bottom 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 

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 (DOE 1986a). 

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

constructed in the southwest portion of the site to contain process wastes from the plant (NLCO 

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

) (NLCO 1977). 

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

of the third and, eventually, fourth pit. 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) (NLCO 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 natural uranium, 46 kg of depleted uranium, and 

2,808 kg of slightly enriched uranium were discharged in 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 uranium). There was some natural 

thorium (e.g., 232Th and 228Th) present in the uranium ore concentrates, which was also separated and 

sent to the raffinate pits. 

2.4.2.10 Weldon Spring Quarry

In 1958, AEC acquired the WSQ, which was previously part of the U.S. Army’s WS Ordnance Works 

(Bechtel 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. 

Prior to 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 following demolition of the 
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Destrehan Street site, with a majority of this waste not submerged, providing a potential source of 

radon exposure (Weldon 1967; ORAUT 2013a, DOE 1990). Measurements in the quarry area in the 

late 1970s and early 1980s (before remediation) averaged 0.65 ± 0.41 pCi/L, indicating that 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 would be limiting for the operational period.

2.4.3 Plant Operations and Radioactive Material of Concern Summary

Table 2-4 lists the WSCP buildings and summarizes the activities that took place in them and potential 

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

2.5 DEPARTMENT OF DEFENSE CONTROL (1967 TO 1985)

In early 1966, the AEC decided to close WSCP at the end of the year resulting 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 U.S. Department of Defense 

(DOD) for use as an herbicide facility. The transfer of facilities to DOD began in March 1968.

At shutdown only a few pounds of pure compounds were present in any single piece of equipment 

with the bulk remaining in building sumps and in 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 returned the WSCP facility to the Army in 1967 (DOE 2003) for the purpose of using portions of 

the feed materials plant for the production of Herbicide Orange to meet needs in Southeast Asia. 

AEC maintained control of Building 434 (which had been used for the storage of ore concentrates), a 

51-acre tract encompassing the four raffinate pits, 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 T of contaminated scrap 

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

National Lead Company of Ohio (NLCO), 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 

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 

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

place between 1969 and 1985.
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Table 2-4. Description of WSCP buildings and operations.

a

Building Description Dates Operations performed Potential radionuclide exposures

101 Sampling Plant Jun 

1957–

1966

Preparation and sampling building designed to process 

approximately 75 tons of low-assay uranium ore 

concentrates per day. 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.

Natural uranium dust

Ra-226

Th-230

Po-210

Pb-210

Rn-222 and its short-lived decay products

Th-232 and decay products (in 1966)

Area 102 

A&B

Refinery Tank Farm Jun 

1957–

1966

Provided facilities for unloading, storing, and transferring

liquid process material required in the refinery operation 

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

quantities.

Natural uranium dust

Ra-226

Th-230

Po-210

Pb-210

Rn-222 and its short-lived decay products

Th-232 and decay products (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 digestion 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.

Natural uranium 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)

104 Lime Storage Facility for storing lime.

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.

Uranium dust or thorium (in 1966)

Rn-222 and short-lived decay products

106 Refinery Sewer 

Sampling

Used as a sampling station for process waste streams.

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 decay products

109, 110 West Drum Storage, 

East Drum Storage

Used to store drums containing ore concentrates and 

process residues.

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)
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Building Description Dates Operations performed Potential radionuclide exposures

202 A&B Green Salt Tank Farm 1957–

1966

Used for tank car unloading and storage of hydrofluoric 

acid (HF) and ammonia.

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 Building 1957–

1966

Powdered magnesium handling building used for 

storage of magnesium.

Pad 303 Served as a material storage pad.

401 Steam Plant 1956–

1966

Steam-generating plant including coal conveyor and 

coal yard.

403 Chemical Pilot Plant 1957–

??

Demonstration of pilot operations. Natural uranium 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–

??

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.

406 Warehouse 1956 Served as a warehouse and office area.

407 Laboratory 1957 Used as an analytical chemistry laboratory. Natural uranium 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.

409 Administration 1957 Contained offices for administrative staff.
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Building Description Dates Operations performed Potential radionuclide exposures

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.

412 Electrical Substation Substation for electrical supply.

413 Cooling Tower and 

Pump House

Water-cooling tower and pump house

414 Salvage Building 1956 Served as a salvage shop and equipment storage 

space.

415 Process Incinerator Incinerator for process materials.

417 Paint Shop ?? Served as the paint shop.

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

427 Primary Sewage 

Treatment Plant

Served as the primary sewage treatment plant for the 

site.

428 Fuel Gas Plant Storage facility for fuel gas.

429 Water Reserve 

Facilities

Water storage (pump house and ground storage tank). 

Also noted to have been a propane gas storage facility.

430 Ambulance Garage Used as an ambulance garage.

43l Laboratory Sewer 

Sampler

Used as a sampling station for process waste streams.

432 Main Sewer Sampler Used as a sampling station for process waste streams.

433 Garage Large equipment garage area. 

434 Storage Ore concentrate storage building.

435 Storage Salvageable equipment storage.

436 Storage Salvageable equipment storage.

437 Records Retention 

Building

Facility used for storage and retention of records.

438 Storage Salvageable equipment storage.

439, 443 Fire Training and 

Storage Building

Facility used for fire training purposes and storage.

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

a. Adapted from U.S. Army (1976).
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2.6 MONITORING AND MAINTENANCE (1975 TO 1985) 

The AEC did not have any contractors performing work on the 52 ac surrounding the WSRP and the 

9-ac WSQ until August of 1975, when it contracted with National Lead of Ohio to perform 

environmental monitoring in the pits and the quarry. In 1981, Bechtel National, Inc. 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 2012). 

2.7 SITE REMEDIATION

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, Inc. 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 WSCP 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 (ANL 

1990) was signed in September 1990. The quarry bulk wastes were excavated and placed in the 

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

limited characterization, a focused Remedial Investigations/Feasibility Study (RI/FS), and a limited 

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

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

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

selected remedy for residual contamination at the quarry site is long-term monitoring to verify that 

conditions at WSQ are 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 RI/FS 

process. These investigations included characterization of groundwater, on-site soil contamination, 

contaminated sediment in off-site surface drainages, lakes, surface water and springs, and 

radiological contaminants in the raffinate wastes. The Record of Decision for Remedial Actions at the 

Chemical Plant Area of the Weldon Spring Site (DOE 1993) 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 pits wastes, and disposal of site wastes in an onsite engineered disposal facility (DOE 

2004). Remediation via removal was completed in 2002, and DOE decided that remediation of the 

shallow groundwater aquifer under the former WSCP would involve institutional controls and 

monitoring to achieve remediation objectives (DOE 2004).

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 WSCP to store excavated waste before placement in the Disposal Cell. A 
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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 completed in late June 1999. As of 2002, construction 

of the Disposal Cell was 85% complete and nearly 1.5 million yd3 of contaminated wastes had been 

placed in it. Final site grading for the raffinate pits, Ash Pond, TSA, SWTP, Frog Pond, and material 

storage areas was performed in 2000.

2.8 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 Worker Advocacy list (DOE 2012), which are from 1955 to 

1967 and from 1975 to the present. Operations did not begin until 1957; thus, this discussion is 

limited to a beginning year of 1957. The site did not have AEC or DOE contractors performing work at 

WSCP outside of these periods (DOE 2012). Table 2-5 summarizes the activities that released 

radionuclides to the Weldon Spring 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 metric tons 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. 

Dec 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).

2.8.1 Airborne Emissions

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

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 2000 around the 

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

1983a, 1983b, 1984, 1985, 1986; MK-Ferguson 1987; 1988; 1989; 1990; 1991; 1992; 1993; 1994; 

1995; 1996; 1997; 1998; 1999; 2000a; and 2001a). Air concentrations of particulates were measured 

during some of the postoperational period. This information suggests that air emissions were of 

potential concern not only during operational activities 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 (DOE 

1986a). 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 
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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 is 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 WSCP (Meshkov et al. 

1986 Table 3.2).

Building 

number

Number 

of stacks Discharge

Height of stack 

(meters)

101 2-3 Yellowcake dust 35

103 1 Yellowcake dust 23

Several UO3

201 6 UO2, UF4, and U3O8 14-34

301 Several UF4 and MgF with 1% uranium 23

1 U3O8

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

a

Fiscal yearb Natural uranium Depleted uranium

Slightly enriched 

uranium Natural thorium

1958 —c —c —c —c

1959 —c —c —c —c

1960 7,200 —c —c —c

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 (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. 

c. No values given for these years. 

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

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

reflect emissions during the later maintenance period and throughout remediation activities. Because 

the site remained in the monitoring and maintenance phase from 1975 to 1985, data from the period 

from 1981 to 1985 could be useful for estimating emissions from 1975 to 1980.

2.8.2 Waterborne Emissions

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

to surface water or groundwater. The four raffinate pits at the WSCP and the WSQ presented 

conditions where contaminated sludge, soil, and rubble were covered or partially covered with 

standing water. During the operational period (1957–1966), the raffinate pits at the WSCP were a 

source of radionuclides that were discharged to surface water. After the WSP operations ceased in 

1966, a small but continuous discharge at the process sewer outfall occurred (Weidner and Boback 

1982). During operations and in the years following plant closure, leaching of sediments in the pits 

and quarry provided a route of discharge to groundwater (Weidner and Boback 1982).
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The four raffinate pits received neutralized residues and waste streams from the various processing 

steps at the WSCP (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 contained in 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 contains 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 it is reported in the materials balance study cited earlier (DOE 1986a). Table 2-8 

summarizes the recorded discharges to the raffinate pits. 

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

a

Fiscal yearb Natural uranium Depleted uranium

Slightly enriched 

uranium 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 DOE (1986a).

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 AEC 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 (DOE 1986a). Supernatant from Pit 4 was never 

decanted, which is why Table 2-9 does not indicate thorium discharges to the sewer. 

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

progeny are 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.
Document No. ORAUT-TKBS-0028-2 Revision No. 01 Effective Date: 05/21/2013 Page 28 of 44

Table 2-9. Estimated annual discharges to sewer (kg).

a

Fiscal yearb Natural uranium Depleted uranium

Slightly enriched 

uranium Natural thorium

1958 —c — — —

1959 — — -- —

1960 3,472 — — —

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 DOE (1986a).

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. — = no values given for these years.

2.8.3 Accidents

No documented accidents at the Weldon Spring Plant site that resulted in exceptionally high 

personnel exposure levels (such as a criticality event) occurred. Interviews conducted with former site 

employees discussed several anecdotal radiological or contamination events, but none of the people 

interviewed reported that the events resulted in high exposures (Personal Communication 2009a; 

Personal Communication 2009b; Personal Communication 2009c; Personal Communication 2009e; 

Personal Communication 2009f; Personal Communication 2009h).

The Health and Safety Division maintained annual logbooks of forms and memos 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 Weldon Spring’s management of and response to high bioassay results (Weldon 1960;

Weldon 1961; Weldon 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 

1962; MCW 1960).

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 

pre-printed 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
Document No. ORAUT-TKBS-0028-2 Revision No. 01 Effective Date: 05/21/2013 Page 29 of 44

Form no. Form title Description

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: Weldon 1960; Weldon 1961; Weldon 1962-1965; MCW 1960; MCW 1962

Specifically, Dupree (1979) cites two accidental exposures of workers which 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. While 

attempting to turn off the valve, he fell into the material on the floor. He was hospitalized and 

ultimately returned to work approximately 11 weeks after the accident. A full report of the incident 

was made (MCW 1961). In the other case, a worker inhaled soluble uranium while trapped in a dust 

enclosure. The notes report that the worker suffered from “CNS effect” (presumably central nervous 

system effect). Mason further speculated that this reaction was due to the chemical toxicity of the 

uranium exposure. 

2.9 HEALTH PROTECTION PRACTICES

2.9.1 Operational Period (1957 to 1966)

According to a descriptive report of the Mallinckrodt contributions between 1942 and 1967 

(Fleishman-Hillard 1967), the design of the WSP “took advantage of the Company’s and the Atomic 

Energy Commission’s (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 

on-site 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.”

A 1965 revision of the Summary of Health Protection Practices for the MCW Uranium Division is 

documented in MCW (1965). The policies and basic principles underlying the health protection 

program are described, and information is included 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 are shielding, semi-remote operations, and worker rotation.

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

Type of radiation Tolerated dose limit

Beta 500 mrepa/wk, whole body or part

Gamma 300 mR/wk, whole body or part

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

Not specified 1,500 mrepa/wk hands and forearms

a. rep = roentgen-equivalent-physical, an obsolete unit of 

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

gamma rays; replaced by the gray.

Table 2-12. Guides for prescribing restricted work based on radiation exposure in 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 the 

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.

2.9.1.1 Badging

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

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

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.

2.9.1.2 Radiological Exposure and Access Control

Workers at the 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; 
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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, semi remote operations, and worker rotation to control exposure; 

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 wherein 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.

2.9.2 Postoperational Period (1975 to Present)

During the monitoring and maintenance period (1975 to 1985), contractors to the Energy Research 

and Development Administration and DOE 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, NLCO (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 (NLCO 1977).

During the remediation period (1985 to present), the WSSRAP project management contractor 

implemented health protection practices in compliance with DOE guidelines and regulations on 

occupational radiation protection (DOE 1981, 1986b, 1989). 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 (MK-Ferguson 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 WSCP and the removal 

of bulk wastes at the WSQ. Applicable DOE guidelines and regulations were specified in 10 CFR 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 the workers spending more than 1 hr/day 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 (MK-Ferguson 2000b), “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.

2.9.2.1 Badging (Postoperational) 

Information on badging procedures during the monitoring and maintenance period (1975 to 1985) is 

not available. For the remediation period (1985 to present), the following information has been 

derived from documentation generated by the project management contractor for the WSSRAP, which 

was a partnership of MK-Ferguson Company and Jacobs Engineering Group, Inc.

According to the January 2000 External Dosimetry Technical Basis Manual (MK-Ferguson 2000b), the 

“WSSRAP has provided personnel dosimetry to radiological workers since October 1986,” just 

following 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. 

2.9.2.2 Radiological Exposure and Access Control

Access to the WSP was limited to authorized personnel during the maintenance 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 

(NLCO 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 

(MK-Ferguson 2000b, 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 and/or HEPA vacuuming; 
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• Plastic dust barriers; 

• Limiting work area access to essential personnel and equipment; 

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

• Training for hazard recognition prior to entry in controlled areas. 

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.

2.10 SUPPLEMENTAL INFORMATION

The following section provides a correlation of the Job Titles to the Job Locations (Building) during the 

operational phase of WSCP. This information is useful in identifying the work locations of the 

claimants during their employment with WSCP, if their job title is known. 

2.10.1 Job Titles and Locations During Operational Phase

Table 2-13 lists job titles and locations for the plant during its operational phase. These were taken 

from an anonymous list that accompanied a memorandum (Dupree 1979) written to describe a visit by 

Mont Mason to Oak Ridge. The notes were presumed to have been made by Mason, who was head 

of Health and Safety for Mallinckrodt for a number of years. 

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

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)
Document No. ORAUT-TKBS-0028-2 Revision No. 01 Effective Date: 05/21/2013 Page 34 of 44

Job title Job type Job location or buildinga

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)

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)
Document No. ORAUT-TKBS-0028-2 Revision No. 01 Effective Date: 05/21/2013 Page 35 of 44

Job title Job type Job location or buildinga

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)

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)
Document No. ORAUT-TKBS-0028-2 Revision No. 01 Effective Date: 05/21/2013 Page 36 of 44

Job title Job type Job location or buildinga

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. 

2.11 ATTRIBUTIONS AND ANNOTATIONS

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

section of this document.
Document No. ORAUT-TKBS-0028-2 Revision No. 01 Effective Date: 05/21/2013 Page 37 of 44

REFERENCES 

AEC (U.S. Atomic Energy Commission), 1968, Chapter 0524 – Standards for Radiation Protection, 

AEC 0524-01, U.S. Atomic Energy Commission, Washington DC, November. [SRDB Ref ID: 

10668]

ANL (Argonne National Laboratory), 1990, Record of Decision for the Management of the Bulk 

Wastes at the Weldon Spring Quarry, Chicago, Illinois. 

Bechtel (Bechtel National), 1983a, Weldon Spring Site (WSS) Environmental Monitoring Report, 

Calendar Year 1981, Oak Ridge, Tennessee, May.

Bechtel (Bechtel National), 1983b, Weldon Spring Site (WSS) Environmental Monitoring Report, 

Calendar Year 1982, Oak Ridge, Tennessee, May.

Bechtel (Bechtel National), 1984, Weldon Spring Site Environmental Monitoring Report, Calendar 

Year 1983, DOE/OR/20722-16, Oak Ridge, Tennessee, June. [SRDB Ref ID: 12530]

Bechtel (Bechtel National), 1985, Weldon Spring Site Environmental Monitoring Report, Calendar 

Year 1984, DOE/OR/20722-58, Oak Ridge, Tennessee, July. [SRDB Ref ID: 12532]

Bechtel (Bechtel National), 1986, Weldon Spring Site Annual Site Environmental Monitoring Report, 

Calendar Year 1985, DOE/OR/20722-101, Oak Ridge, Tennessee, September. [SRDB Ref 

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GLOSSARY

U.S. Atomic Energy Commission (AEC)

Original agency established for nuclear weapons and power production; a predecessor to the 

Energy Research and Development Agency and the U.S. Department of Energy.

curie (Ci)

A special unit of activity. One curie equals 3.7 × 1010 nuclear transitions per second.

dose equivalent (H) 

The product of the absorbed dose D, the quality factor Q, and any other modifying factors. 

The special unit is the rem. When D is expressed in gray, H is in sieverts, where 

1 sievert equals 100 rem.

dosimeter

A device used to measure the quantity of radiation received. A holder with radiation-absorbing 

elements (filters) and an insert with radiation-sensitive elements packaged to provide a record 

of absorbed dose or dose equivalent received by an individual. 

dosimetry

The science of assessing absorbed dose, dose equivalent, effective dose equivalent, etc., 

from external or internal sources of radiation. 

dosimetry system

A system used to assess dose equivalent from external radiation to the whole body, skin, or 

extremities. This includes the fabrication, assignment, and processing of dosimeters as well 

as interpretation and documentation of the results.

exposure

As used in the technical sense, exposure refers to a measure expressed in roentgens of the 

ionization produced by photons (i.e., gamma and X-rays) in air. 

extremity

That portion of the arm extending from and including the elbow through the fingertips, and that 

portion of the leg extending from and including the knee and patella through the tips of the 

toes.

film

In general, a packet that contains one or more pieces of film in a light-tight wrapping. When 

developed, the film has an image caused by radiation that can be measured using an optical 

densitometer.

gamma rays

Electromagnetic radiation (photons) originating in atomic nuclei. Gamma rays are physically 

identical to X-rays, the only essential difference being that X-rays do not originate in the 

nucleus. 

hydrofluorination

Chemical conversion to a form containing fluorine.
Document No. ORAUT-TKBS-0028-2 Revision No. 01 Effective Date: 05/21/2013 Page 44 of 44

isotope

One of a set of chemically identical species of atom which have the same atomic number but 

different mass numbers (different isotopes of an element having the same number of protons 

but different numbers of neutrons and thus different atomic numbers).

neutron

A basic particle that is electrically neutral weighing nearly the same as the hydrogen atom.

photon

A unit or "particle" of electromagnetic radiation consisting of X- or gamma rays. 

quality factor (Q)

A modifying factor used to derive dose equivalent from absorbed dose.

radiation

Alpha, beta, neutron, and photon radiation. 

radioactivity

The spontaneous emission of radiation, generally alpha or beta particles, gamma rays, and 

neutrons from unstable nuclei.

radionuclide

A radioactive isotope of an element, distinguished by atomic number, atomic weight, and 

energy state.

raffinate

A term loosely applied to waste from the uranium or thorium extraction step. Solids that result 

from the neutralization of this waste are also called raffinates.

rem

A unit of dose equivalent equal to the product of the number of rad absorbed and the quality 

factor. The word derives from roentgen equivalent in man. 

roentgen

A unit of exposure to gamma (or X-ray) radiation. It is defined precisely as the quantity of 

gamma (or X-) rays that will produce a total charge of 2.58 × 10-4 coulomb in 1 kilogram of dry 

air. An exposure of 1 roentgen is approximately equivalent to an absorbed dose of 1 rad in 

soft tissue for higher (more than about 100 kilovolt-electron) energy photons.

shallow dose equivalent (Hs) 

Dose equivalent at a depth of 0.007 centimeter in tissue.

shielding

Any material or obstruction that absorbs (or attenuates) radiation and thus tends to protect 

personnel or materials from radiation.

sievert

The International System unit for dose equivalent, where 1 sievert equals 100 rem.

X-ray

Ionizing electromagnetic radiation of external nuclear origin.