DOE Review 04/14/2015

Division of Compensation Analysis and Support

Technical Basis Document for Nuclear Metals Inc.

Document Number:

DCAS-TKBS-0010

Effective Date: 04/24/2015

Revision No.: 00

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Subject Expert: David Allen

Approval: Signature on file Date: 04/24/2015

Supersedes:

None

James W. Neton, Associate Director for Science

TABLE OF CONTENTS

Section Page

1.0 Introduction ............................................................................................................................3

2.0 Site Description and Operational History...............................................................................4

3.0 Process Description ................................................................................................................5

4.0 Internal Dose...........................................................................................................................5

5.0 External Dose .........................................................................................................................6

6.0 Residual Contamination .........................................................................................................6

7.0 Occupational Medical Dose....................................................................................................9

8.0 References ............................................................................................................................10

LIST OF TABLES

Table Page

Table 1 – Nuclear Metals, Inc. Dosimeter Program................................................................................6

Table 2 – NMI Residual Period External Dose.......................................................................................8

Table 3 – NMI Residual Period Intakes..................................................................................................8
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ISSUE

AUTHORIZATION

DATE

EFFECTIVE

DATE REV. NO. DESCRIPTION

04/07/2015 04/24/2015 00 Document initiated to establish a 

technical basis for radiation dose 

reconstructions for former workers of 

Nuclear Metals Inc.
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1.0 Introduction

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

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

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

preparation of dose reconstructions at particular Department of Energy (DOE) or Atomic 

Weapons Employer (AWE) facilities or categories of DOE or AWE facilities. They will be 

revised in the event additional relevant information is obtained about the affected DOE or AWE 

facility(ies). These documents may be used to assist NIOSH staff in the evaluation of Special 

Exposure Cohort (SEC) petitions and the completion of the individual work required for each 

dose reconstruction.

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

that served a specific purpose at a DOE or AWE facility. It does not mean, nor should it be 

equated to, an “AWE facility” or a “DOE facility.” The terms AWE and DOE facility are 

defined in sections 7348l(5) and (12) of the Energy Employees Occupational Illness 

Compensation Program Act of 2000 (EEOICPA), respectively. A DOE facility is defined as 

“any building, structure, or premise, including the grounds upon which such building, structure, 

or premise is located ... in which operations are, or have been, conducted by, or on behalf of, the 

[DOE] (except for buildings, structures, premises, grounds, or operations ... pertaining to the 

Naval Nuclear Propulsion Program),” and with regard to which the DOE has or had a proprietary 

interest; or “entered into a contract with an entity to provide management and operation, 

management and integration, environmental remediation services, construction, or maintenance 

services.” 42 U.S.C. § 7384l(12). On the other hand, an AWE facility means “a facility, owned 

by an atomic weapons employer, that is or was used to process or produce, for use by the United 

States, material that emitted radiation and was used in the production of an atomic weapon, 

excluding uranium mining or milling.” 42 U.S.C. § 7384l(5). The Department of Energy (DOE) 

determines whether a site meets the statutory definition of an AWE facility and the Department 

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

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

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

designated time period and location (i.e., covered employee). After DOL determines that a claim 

meets the eligibility requirements under EEOICPA, DOL transmits the claim to NIOSH for a 

dose reconstruction. EEOICPA provides, among other things, guidance on eligible employment 

and types of radiation exposure to be included in an individual dose reconstruction. Under 

EEOICPA, eligible employment at an AWE facility is categorized as employment either (1) 

during “a period when the employer was processing producing, for the use by the United States, 

material that emitted radiation and was used in the production of an atomic weapon, excluding 

uranium mining and milling,” (i.e., the operational period); or (2) during a period that NIOSH 

has determined that “there is a potential for significant residual contamination outside of the 

period in which weapons-related production occurred,” (i.e., the residual contamination period).

42 U.S.C. § 7384l(3).

Based on the abovementioned definition for eligible employment during an AWE facility’s 

operational period, NIOSH includes radiation exposures incurred in the performance of duty, 

such as medical X-rays received as a condition of employment for participating in DOE projects,
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at an AWE facility in dose reconstructions. This may include radiation exposure related to the 

Naval Nuclear Propulsion Program and any radiation exposure received from the production of 

commercial radioactive products that were concurrently manufactured by the AWE facility 

during the operational period. In contrast, only two categories of radiation exposure as defined 

in 42 U.S.C. § 7384n(c)(4) should be included in dose reconstructions for claims involving 

employment during the residual contamination period. First, NIOSH must include exposures to 

radiological contaminants resulting from activities that had a nuclear-weapon nexus or conducted 

by or on behalf of the DOE (with an exclusion of activities related to, among other things, the

Naval Nuclear Propulsion Program) that took place during the operational period. 42 U.S.C. § 

7384n(c)(4)(A). Second, radiation doses from sources not included in the first category but 

which cannot be distinguished through reliable documentation should also be included in dose 

reconstructions. 42 U.S.C. § 7384n(c)(4)(B). Furthermore, because all DOE-related activities 

have ceased during the residual contamination period, NIOSH does not include doses from 

medical X-rays performed during the residual contamination period (NIOSH 2007) in dose 

reconstructions.

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

performance of duty as a condition of employment for DOE-related activities at an AWE facility. 

Therefore these exposures are not included in dose reconstructions for either the operational or 

residual contamination period (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

The following information from the Department of Energy’s Office of Health, Safety and 

Security EEOICPA Find Facilities webpage defines the EEOICPA covered periods for Nuclear 

Metals Inc.

Site: Nuclear Metals Inc.

Location: West Concord, Massachusetts

Covered Period: AWE October 29, 1958-1990, Residual Radiation 1991-March 1, 2011

This document contains a summary of the description of the site as well as the Atomic Energy 

Commission activities performed there, and provides the technical basis to be used to evaluate 

the occupational radiation doses for EEOICPA claims.

2.0 Site Description and Operational History

Nuclear Metals, Inc. (NMI) was incorporated in 1954 as a DOE contractor to take over the 

research and development work previously performed by MIT's Metallurgical Laboratory. The 

work performed by NMI employees during this period is covered under EEOICPA under a 

separate facility listing. (See the Hood Building.) However, on October 29, 1958, the company 

moved from the Hood Building to their new West Concord location, and that is the location 

described in this document.
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In 1958, NMI began operating as an AWE facility at the West Concord location producing 

depleted uranium products, primarily as penetrators for armor-piercing ammunition. It also 

supplied copper-plated uranium billets that were used to fuel Savannah River's production 

reactors. Other work at this facility included the manufacture of metal powders for medical 

applications, photocopiers and other applications. Thorium and thorium oxide were also handled 

at the site under license to the NRC.

On December 7, 2012 the Secretary of Health and Human Services designated a Special 

Exposure Cohort (SEC) for NMI from October 29, 1958 through December 31, 1979. On July 

11, 2014 an additional SEC was designated from January 1, 1980 through December 31, 1990. 

Both designations indicated internal dose from thorium and enriched uranium, including their 

progeny, could not be estimated with sufficient accuracy. 

3.0 Process Description 

In the beginning of operations, after the transfer to Concord, operations consisted primarily of 

research and development in fundamental metallurgy, physical metallurgy, chemical metallurgy, 

engineering and product development, fuel element development and manufacture, and high 

temperature materials (MACTEC 2004, pdf p. 29). Many, if not all of these operations were 

carried over from the work at the Hood Building. Most of the operations at the Concord site 

were for the United States Atomic Energy Commission (AEC) and the Department of Defense 

(DOD). Additional activities were completed for private industry in the investigation and 

development of materials for missiles, airframes, and other components. 

In the mid-1970s, the focus of Concord site operations shifted from research and development to 

large-scale production. Large-scale production included the manufacture of depleted uranium 

(DU) shields, counter weights, and armor penetrators; the manufacture of metal powders, 

beryllium and beryllium alloy-parts productions; and the manufacture of specialty titanium parts. 

Reactor fuel development, which began at the MIT facilities in the 1940s, also continued during 

this period. 

4.0 Internal Dose

The Secretary of Health and Human Services designated a class of employees to be added to the 

SEC. The class includes employees from the entire operational period of NMI. NIOSH 

determined and the Secretary concurred that internal dose from thorium or its progeny as well as 

internal dose from enriched uranium and its progeny could not be estimated. However, NIOSH 

did determine that internal dose from normal or depleted uranium could be estimated. 

Dosimetry records exist for the majority of employees of NMI. These records include urinalysis 

for uranium by fluorometric technique which should be used to estimate the internal dose for 

most employees. The minimum detectable activity for this type of analysis is typically 0.005 

mg/L or less (ORAUT 2005) so 0.005 mg/L should be used for these samples. A specific

activity of 683 pCi/mg for natural uranium should be used.
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For unmonitored workers, ORAUT-OTIB-0084 should be used. The intakes in that document 

represent the analysis of urine data from the monitored workers at NMI. After 1990, any intakes 

are primarily from commercial work which is not covered in the residual period under EEOICPA

so intakes from ORAUT-OTIB-0084 should not be used after 1990. An internal dose estimate 

after 1990 is contained in section 6 of this document, the residual contamination section.

5.0 External Dose

The majority of employees at Nuclear Metals Inc. were monitored for external radiation using 

film badges provided by commercial providers. A discussion of the external dosimetry program 

is contained in the NMI evaluation report (NIOSH 2012) and includes a table of film badge 

information including applicable dates, providers, exchange frequency and minimum detectable 

sensitivity (MDS). The table is recreated below with an additional line added to describe the 

period after 1983 based on dosimetry records (Monitoring 1990, pg 25).

Table 1 – Nuclear Metals, Inc. Dosimeter Program

Dosimeter 

Type

Dosimeter 

Provider

Period of Use Exchange 

Frequency

MDS (mrem)

Skin Deep

β/γ film NCA 10/1/1958 – 10/26/1959 4 weeks - 10

β/γ film CRI 10/26/1959 – 5/1/1961 6 weeks 10 5

β/γ film NCA 5/1/1961 – 2/7/1968 6.5 weeks - 10

β/γ film Landauer 2/7/1968 – 12/31/1983 4 weeks 10 40

TLD Landauer 1/1/1984 – 12/31/1990 Monthly 10 10

Landauer records include a variety of information that may be useful but also can be confusing. 

The reports provide a page of codes on the back of the reports but the back is not always 

included when data is captured. One page of codes is included in data captured from 1990 

(Monitoring 1990, pg 3). These codes can be used to interpret Landauer records. There are also

some codes at the bottom of the record side of the Landauer dosimetry reports that describe the 

“use”. The use codes most often seen on NMI records are 1, 3 and 4 which describe “Whole 

Body”, Right Finger” and “Left Finger” respectively. Individuals with extremity measurements 

will normally have multiple lines on a single dosimetry report one for each type of “use” of the 

dosimeter. Care must be taken not to mix extremity results with whole body results. Also some 

lines will have a code “CPB in column 7 of the report indicating it is a combined x ray, gamma 

ray and beta particle exposure. Those should have a “B” in a second line indicating the beta 

exposure. The x ray and gamma ray exposure is then found by subtracting the beta dose from 

the combined dose.

Unmonitored workers could be assigned a co-worker dose based on an analysis of individual 

doses at NMI. However, this analysis has not yet been performed. Since NIOSH received 

dosimetry records and most workers were monitored, the analysis has not been necessary. If in 

the future, a dose reconstruction is necessary for a case with no dosimetry records, the dose 

reconstructors should utilize overestimating or underestimating techniques to estimate the dose. 

If this fails, a co-worker analysis for the applicable years will be undertaken.

6.0 Residual Contamination
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NMI continued commercial operations after DOE work. However, employees could continue to 

receive radiation dose from any contamination remaining from DOE work. 

ORAUT-OTIB-0084 was utilized to estimate the uranium contamination remaining after the end 

of the DOE work. ORAUT-OTIB-0084 is the uranium internal co-worker analysis and is based 

on urine samples submitted by workers at NMI. In that document, intakes derived from urine 

samples were broken into three time periods with the highest intake rate ending 12/31/1983. The 

geometric mean of the intake rate distribution was used as the most appropriate value for 

determine plant wide contamination levels. Since the solubility of the inhaled uranium affects 

the calculated intake rate, the most favorable solubility (Type S) was used. This intake rate (574 

pCi/day) is equivalent to inhaling an airborne concentration of 87.3 pCi/m3continuously. Using 

techniques in Battelle-TBD-6000 (Battelle 2011), the contamination level was estimated 

assuming this airborne concentration settled at a rate of 0.00075 m/s for 30 days. This results in 

a contamination value of 169,700 pCi/m2.

From that contamination level, a resuspension factor of 1x10-5 m-1 was used to estimate the 

airborne concentration of 1.7 pCi/m3. This results in an intake rate of 11.2 pCi/day. Since the 

data used for this calculation was urine samples, no separate ingestion intake calculation is 

necessary. To determine the external dose rates from the contamination, uranium dose 

conversion factors from Battelle-TBD-6000 were used. The resulting dose rates are 0.3 mrem/yr 

photon and 28.8 mrem/yr beta assuming 2000 hours per year of exposure.

To estimate the thorium contamination, it is first noted that the site’s production area removable 

contamination limit for uranium was 25000 dpm/100 cm2 while the contamination level 

previously estimated in a favorable manner was 3767 dpm/100 cm2(169,700 pCi/m2). This 

implies the site kept contamination well within their guidelines. Therefore, the site’s thorium 

contamination guideline of 5000 dpm/100 cm2 will be used as the residual thorium 

contamination at the site. 

The site’s thorium contamination limit is based on total alpha activity. Since thorium has a long 

decay chain there are several alpha decays for every thorium-232 (Th-232) decay. This estimate 

will assume the thorium is in equilibrium through radium-224 (Ra-224). Three of the isotopes in 

that part of the decay chain decay by alpha emission. Therefore, the Th-232 activity will be 

assumed to be 1/3 of this activity and the activity of 4 other nuclides (Ra-226, Ac-228, Th-228, 

Ra-224) will be equal to the Th-232 activity.

From the surface contamination value, the airborne concentration was determined using a 

resuspension factor of 1x10-5 m-1. Each person is assumed to be exposed to this level of airborne 

activity for 2000 hours each year resulting in an inhalation of 11 dpm/day at the beginning of the 

residual period to each of the five nuclides. For subsequent years, the contamination is assumed 

to be slowly depleted at the rate specified in ORAUT-OTIB-0070.

An estimate of intakes from ingesting contamination is also included. The contamination is 

assumed to be ingested at a rate of 1.1E-4 m2/hr (NUREG/CR 5512). This results in an 

ingestion rate of 100.5 dpm/day for each of the five nuclides. Again, this is the calculated 
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ingestion rate for the first year of the residual period. Subsequent years are decreased to account 

for the depletion of the weapons related contamination at the rate specified in ORAUT-OTIB0070.

The external dose from thorium contamination was determined using dose conversation factors 

in EPA-FGR-012. Surface contamination dose conversion factors for effective dose and skin 

dose were used for each of the five nuclides. Workers were assumed to be exposed to this level 

of radiation for 2000 hours each year. This results in a dose rate of 1.9 mrem/yr for photon dose 

and 9.6 mrem/yr for beta dose. 

A summary of the internal and external dose estimates for the residual contamination period at 

NMI are included in Table 2 and Table 3 below. 

Table 2 – NMI Residual Period External Dose

Years Uranium Thorium Total

Photon 

(mrem/yr)

Beta 

(mrem/yr)

Photon 

(mrem/yr)

Beta 

(mrem/yr)

Photon 

(mrem/yr)

Beta 

(mrem/yr)

1991 – 2011 0.3 28.8 1.9 9.6 2.2 38.3

Table 3 – NMI Residual Period Intakes

Year Uranium Inhalation

(pCi/day)

Thorium Inhalation a

(dpm/day)

Thorium Ingestion a

(dpm/day)

1991 11.2 11.0 100.5

1992 8.7 8.6 78.7

1993 6.8 6.7 61.6

1994 5.4 5.3 48.2

1995 4.2 4.1 37.8

1996 3.3 3.2 29.6

1997 2.6 2.5 23.2

1998 2.0 2.0 18.1

1999 1.6 1.5 14.2

2000 1.2 1.2 11.1

2001 1.0 0.9 8.7

2002 0.8 0.7 6.8

2003 0.6 0.6 5.3

2004 0.5 0.5 4.2

2005 0.4 0.4 3.3

2006 0.3 0.3 2.6

2007 0.2 0.2 2.0

2008 0.2 0.2 1.6

2009 0.1 0.1 1.2

2010 0.1 0.1 1.0

2011 0.1 0.1 0.8

a Assign thorium intake to each of five nuclides (Th-232, Ra-228, Ac-228, Th-228, Ra-224)
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The values for thorium are considered a bounding estimate because it is based on the site’s 

surface contamination guideline and indications are that the true values were kept below those 

guidelines. The values for uranium are also considered bounding because they are based on 

operational airborne values derived from urinalysis results. The values used are from the period 

ending 7 years before the residual period. Values at the end of the operational period were 

actually lower.

7.0 Occupational Medical Dose

No documentation regarding occupational medical dose specific to NMI was found. Information 

to be used in dose reconstructions, for which no specific information is available, is provided in

ORAUT-OTIB-0006, Technical Information Bulletin: Dose Reconstruction from 

Occupationally Related Diagnostic X-Ray Procedures (ORAUT 2011). The assumed frequency

in this document is PA chest X-ray for pre-employment, annual, and termination examinations

during the operational years. Occupational medical dose is not covered during the residual 

period (NIOSH 2010). Annual organ doses are entered into the NIOSH-IREP program as the 

annual dose due to an acute exposure to photons (E=30-250 keV). The distribution is assumed to 

be normal with a standard deviation of 30%. 
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8.0 References

Battelle 2011, Bettelle-TBD-6000, Site Profiles for Atomic Weapons Employers that Worked 

Uranium Metals, Rev 01, June 17, 2011.

DOE, Office of Health, Safety and Security, EEOICPA web site.

http://www.dol.gov/owcp/energy/regs/compliance/EEOICPA_FacilityList.pdf

EPA-FGR-12, Eckerman, KF and JC Ryman, 1993, External exposure to radionuclides in air, 

water, and soil. Federal Guidance Report No. 12. EPA-402-R-93-081. Environmental 

Protection Agency. Washington, DC.

MACTEC 2004, MACTEC Engineer Inc., Health and Safety Plan Nuclear Metals Superfund 

Site Remedial Investigation/Feasibility Study concord, Massachusetts; September 29, 2004, 

SRDB 105264.

Monitoring 1990, Film Badge Data for 1990, Landauer, various dates throughout 1990, SRDB 

113356.

NIOSH 2010, Radiation Exposures Covered for Dose Reconstructions Under Part B of the 

Energy Employees Occupational Illness Compensation Program Act, Rev 1, OCAS-IG-003, 

National Institute for Occupational Safety and Health, Office of Compensation Analysis and 

Support, Cincinnati, Ohio, October 5, 2010.

NIOSH 2012, SEC Petition Evaluation Report for Petition SEC-00195, Nuclear Metals, Inc., 

National Institute for Occupational Safety and Health (NIOSH), August 30, 2012, SRDB 

130905.

NUREG/CR 5512 Vol. 1, Residual Radioactive Contamination From Decommissioning, 

Prepared for the Nuclear Regulatory Commission, October 1992 

ORAUT (Oak Ridge Associated Universities Team) 2005, ORAUT-TKBS-0003, Technical 

Basis Document: Savannah River Site, Rev 03, April 5, 2005.

ORAUT (Oak Ridge Associated Universities Team) 2011, ORAUT-OTIB-0006, Technical 

Information Bulletin: Dose Reconstruction from Occupational Medical X-Ray Procedures, Rev 

04, June 20, 2011.

ORAUT (Oak Ridge Associated Universities Team) 2012, ORAUT-OTIB-0070, Technical 

Information Bulletin: Dose Reconstruction During Residual Radioactivity Periods at Atomic 

Weapons Employer Facilities, Rev 01, March 5, 2012.

ORAUT (Oak Ridge Associated Universities Team) 2013, ORAUT-OTIB-0084, Technical 

Information Bulletin: Internal Coworker Dosimetry Data for Nuclear Metals, Inc., Rev 00, 

November 15, 2013.