Draft

Advisory Board on Radiation and Worker Health

National Institute for Occupational Safety and Health

A Review of NIOSH’s Program Evaluation Report 

DCAS-PER-070, “Nuclear Metals Inc.” 

Contract No. 75D30119C04183

Document No. SCA-TR-2023-PER070, Revision 0

Prepared by

Amy Mangel, CHP, MS

Rose Gogliotti, MS

SC&A, Inc.

2200 Wilson Blvd., Suite 300

Arlington, VA 22201-3324

January 30, 2024 

DISCLAIMER

This is a working document provided by the Centers for Disease Control and Prevention (CDC) 

technical support contractor, SC&A for use in discussions with the National Institute for 

Occupational Safety and Health (NIOSH) and the Advisory Board on Radiation and Worker 

Health (ABRWH), including its Working Groups or Subcommittees. Documents produced by 

SC&A, such as memorandum, white paper, draft or working documents are not final NIOSH or 

ABRWH products or positions, unless specifically marked as such. This document prepared by 

SC&A represents its preliminary evaluation on technical issues.

NOTICE: This document has been reviewed to identify and redact any information that is 

protected by the Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 
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SC&A, Inc. technical support for the Advisory Board on Radiation and Worker Health’s 

review of NIOSH dose reconstruction program

Document title A Review of NIOSH’s Program Evaluation Report DCAS-PER-070, 

“Nuclear Metals Inc.”

Document number SCA-TR-2023-PER070

Revision number 0 (Draft)

Supersedes NA

Effective date January 30, 2024 

Task manager Kathleen Behling [signature on file]

Project manager Bob Barton, CHP [signature on file]

Document reviewer(s) Kathleen Behling [signature on file]

Bob Barton, CHP [signature on file]

Record of revisions

Revision number Effective date Description of revision

0 (Draft) 1/30/2024 Initial issue
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Table of Contents

Abbreviations and Acronyms........................................................................................... 4

1 Statement of Purpose............................................................................................... 5

2 Relevant Background Information............................................................................. 7

3 Subtask 1: Identify the Circumstances that Necessitated DCAS-PER-070 .............. 8

3.1 Chronology of events ......................................................................................... 8

3.2 SC&A’s comments ............................................................................................. 8

4 Subtask 2: Assess NIOSH’s Specific Methods for Corrective Action........................ 9

4.1 Internal dose estimate........................................................................................ 9

4.2 External dose estimate..................................................................................... 10

4.3 Residual period internal dose estimate ............................................................ 12

4.4 Residual period external dose estimate ........................................................... 13

4.5 Occupational medical dose estimate................................................................ 14

5 Subtask 3: Evaluate the PER’s Stated Approach for Identifying the Number of DRs 

Requiring Reevaluation of Dose.................................................................................... 15

5.1 NIOSH’s selection criteria ................................................................................ 15

5.2 SC&A’s comments ........................................................................................... 15

6 Subtask 4: Conduct Audits of a Sample Set of Reevaluated DRs Mandated by 

DCAS-PER-070 ............................................................................................................ 16

7 References ............................................................................................................. 17
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Abbreviations and Acronyms

ABRWH, Board Advisory Board on Radiation and Worker Health

Ac actinium

DCAS Division of Compensation Analysis and Support

DR dose reconstruction

dpm/100 cm2 disintegrations per minute per 100 square centimeters

dpm/day disintegrations per minute per day

EPA U.S. Environmental Protection Agency

FGR Federal Guidance Report

IREP Interactive RadioEpidemiological Program

keV kiloelectron volt

m-1 per meter

m2

/hr square meters per hour

MDS minimum detectable sensitivity

mR milliroentgen

mrad millirad

mrem millirem

mrem/yr millirem per year

NA not applicable

NIOSH National Institute for Occupational Safety and Health

NMI Nuclear Metals Inc.

NRC U.S. Nuclear Regulatory Commission

ORAUT Oak Ridge Associated Universities Team

pCi/day picocuries per day

pCi/m2 picocuries per square meter

pCi/m3 picocuries per cubic meter

pCi/mg picocuries per milligram

PER program evaluation report

POC probability of causation

Ra radium

SEC special exposure cohort

SRDB Site Research Database

TBD technical basis document

Th thorium
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1 Statement of Purpose

To support dose reconstruction (DR), the National Institute for Occupational Safety and Health 

(NIOSH) and the Oak Ridge Associated Universities Team (ORAUT) assembled a large body of 

guidance documents, workbooks, computer codes, and tools. In recognition of the fact that all of 

these supporting elements in DR may be subject to revisions, provisions exist for evaluating the 

effect of such programmatic revisions on the outcome of previously completed DRs. Such 

revisions may be prompted by document revisions due to new information, misinterpretation of 

guidance, changes in policy, and/or programmatic improvements.

A program evaluation report (PER) provides a critical evaluation of the effects that a given issue 

or programmatic change may have on previously completed DRs. This includes a qualitative and 

quantitative assessment of potential impacts. Most important in this assessment is the potential 

impact on the probability of causation (POC) of previously completed DRs with POCs less than 

50 percent.

During a teleconference by the Advisory Board on Radiation and Worker Health (Board) 

Subcommittee for Procedure Reviews on June 21, 2023, the Board tasked SC&A to review 

DCAS-PER-070, revision 0 (NIOSH, 2016; “PER-070”), which was issued to address the 

impacts on previously completed claims of issuing DCAS-TKBS-0010, revision 00 (NIOSH, 

2015), the technical basis document (TBD) for Nuclear Metals Inc. (NMI). In conducting a PER 

review, SC&A is committed to perform the following five subtasks, each of which is discussed 

in this report:

• Subtask 1: Assess NIOSH’s evaluation and characterization of the issue addressed in the 

PER and its potential impacts on DR. Our assessment intends to ensure that the issue was 

fully understood and characterized in the PER.

• Subtask 2: Assess NIOSH’s specific methods for corrective action. When the PER 

involves a technical issue that is supported by documents (e.g., white papers, technical 

information bulletins, procedures) that have not yet been subjected to a formal SC&A 

review, subtask 2 will include a review of the scientific basis and/or sources of 

information to ensure the credibility of the corrective action and its consistency with 

current/consensus science. Conversely, if such technical documentation has been 

formalized and previously subjected to a review by SC&A, subtask 2 will simply provide 

a brief summary and conclusion of this review process.

• Subtask 3: Evaluate the PER’s stated approach for identifying the universe of potentially 

affected DRs and assess the criteria by which a subset of potentially affected DRs was 

selected for reevaluation. The second step may have important implications where the 

universe of previously denied DRs is very large and, for reasons of practicality, NIOSH’s 

reevaluation is confined to a subset of DRs that, based on their scientific judgment, have 

the potential to be significantly affected by the PER. In behalf of subtask 3, SC&A will 

also evaluate the timeliness of the completion of the PER.
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• Subtask 4: Conduct audits of DRs affected by the PER under review. The number of 

DRs selected for audit for a given PER will vary. (It is assumed that the Board will select 

the DRs and the total number of DR audits for each PER.) 

• Subtask 5: Prepare a written report that contains the results of DR audits under 

subtask 4, along with our review conclusions. 
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2 Relevant Background Information

On October 29, 1958, NMI moved to West Concord, Massachusetts. NMI operated as an Atomic 

Weapons Employer facility from 1958 through 1990, with a residual period from 1991 through 

2011. Beginning in 1958, NMI began producing depleted uranium products for armor-piercing 

ammunition. NMI also supplied copper-plated uranium billets for Savannah River’s production 

reactors. Other work conducted at NMI included manufacturing metal powders for medical 

applications, photocopiers, and other applications. NMI also handled thorium and thorium 

oxides. 

Two classes of workers were added to the Special Exposure Cohort (SEC) for NMI. SEC 

Petition 195 established a class of workers that covered from October 29, 1958, through 

December 31, 1979, and an addendum to that petition established a class from January 1, 1980,

through December 31, 1990. Both classes indicated that internal dose from thorium and enriched 

uranium could not be estimated with sufficient accuracy.
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3 Subtask 1: Identify the Circumstances that Necessitated 

DCAS-PER-070

3.1 Chronology of events

Dose reconstructions for claims from NMI were originally performed using site research that 

was eventually summarized in the SEC evaluation report for SEC Petition 195. On April 24, 

2015, NIOSH issued DCAS-TKBS-0010, the TBD for NMI (NIOSH, 2015). PER-070 (NIOSH, 

2016) evaluated the effects of using the TBD on all previously completed NMI claims. 

3.2 SC&A’s comments

Programmatic revisions that may affect the outcome of previously completed DRs and mandate 

the need for a PER include any revisions to guidance documents that may result in the 

assignment of a higher dose. 

SC&A believes that the issuance of a TBD for NMI dose estimates is justification for 

reevaluating worker doses, as defined in PER-070. SC&A concurs with NIOSH’s decision to 

issue PER-070 and has no findings. 
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4 Subtask 2: Assess NIOSH’s Specific Methods for Corrective Action

Prior to the issuance of DCAS-TKBS-0010 (NIOSH, 2015), DRs for NMI were performed using 

site research. Since SC&A has not previously reviewed DCAS-TKBS-0010, SC&A’s review of 

PER-070 includes an evaluation of its guidance to assess the scientific basis and sources of 

information to ensure the credibility of the corrective action. 

4.1 Internal dose estimate

As stated in DCAS-TKBS-0010 (NIOSH, 2015), NIOSH had previously determined that the 

internal dose from thorium and enriched uranium and their progeny could not be estimated, but 

that internal dose from natural or depleted uranium could be estimated. Internal dosimetry 

records are believed to exist for the majority of NMI employees, which include uranium 

urinalyses by fluorometric technique. The TBD states that the assumed minimum detectable 

activity for this analysis is 0.005 milligrams per liter, and that a specific activity of 

683 picocuries per milligram (pCi/mg) should be used for natural uranium (NIOSH, 2015). To 

determine the internal dose due to natural and depleted uranium during the operational period for 

workers without internal dosimetry records, the TBD indicates that the NMI internal coworker 

dosimetry guidance document ORAUT-OTIB-0084, revision 00 (ORAUT, 2013; “OTIB-0084”), 

should be used. 

4.1.1 SC&A’s comments

SC&A reviewed section 4.0 of DCAS-TKBS-0010. SC&A agrees with NIOSH that any 

available internal dosimetry records should be used for a given DR. SC&A also agrees that for 

unmonitored workers, OTIB-0084 should be used to assess internal dose from uranium. 

However, it should be noted that this document has not yet been reviewed by SC&A but is 

outside of the scope of this review. SC&A also notes that OTIB-0084 is a co-exposure model 

that has not been updated to meet the newer guidance in DCAS-IG-006, revision 00, “Criteria for 

the Evaluation and Use of Co-Exposure Datasets” (NIOSH, 2020). 

Observation 1: Clarification needed on type of uranium assumed for exposures of 

monitored and unmonitored workers

It appears that the assumptions for what type of uranium a worker was exposed to differs 

whether they were monitored or not. When discussing the conversion of fluorometric uranium 

urinalysis data from mass units to activity units, DCAS-TKBS-0010 (NIOSH, 2015) suggests 

using a specific activity for natural uranium of 683 pCi/mg. However, section 3.1 of OTIB-0084 

(ORAUT, 2013, p. 7) discusses how NIOSH handled urinalysis data in the development of the 

co-exposure model and states that NIOSH used a “uranium-specific activity” of 0.36 picocuries 

per microgram (or 360 pCi/mg). This is consistent with the depleted uranium value reported in

bioassay data sheets from 1983 (Nuclear Metals, 1983a). SC&A requests clarification about the 

reasoning for the guidance that workers who were monitored are assumed to be exposed to 

natural uranium, and workers who were not monitored are assumed to be exposed to depleted 

uranium.

Additionally, SC&A noted that the specific activities of natural and depleted uranium used by 

NIOSH in DCAS-TKBS-0010 (NIOSH, 2015) and OTIB-0084 (ORAUT, 2013) differ from the 

specific activities listed in table 3.1 of Battelle-TBD-6000, revision 1 (NIOSH, 2011). SC&A 
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believes it would be more consistent to use the values from Battelle-TBD-6000 (NIOSH, 2011) 

in DCAS-TKBS-0010 (NIOSH, 2015) unless more precise site-specific enrichment values are 

available such as in OTIB-0084. 

Observation 2: Additional information needed regarding other bioassay measurements 

NMI workers could have received during operations

According to the SEC 195 petition evaluation report addendum (NIOSH, 2014), the first in vivo 

bioassay for NMI was conducted in April 1981, after it was suspected that a worker had an 

overexposure to airborne depleted uranium. Beginning in 1982, NMI acquired a whole-body 

counter for uranium lung counting and performed over 800 lung counts from 1982 through 1990. 

However, section 4.0 of DCAS-TKBS-0010 (NIOSH, 2015) does not discuss any lung counting 

performed at NMI, nor does it include any information for how the measurements may be used 

in a dose reconstruction. SC&A believes that DCAS-TKBS-0010 would benefit from a 

discussion of all other possible bioassay techniques used at NMI during the operational period 

that may be included in an NMI worker’s dosimetry records. This would include whether the 

in vivo records could potentially be used to assess internal doses in place of the urinalysis model 

from OTIB-0084 (ORAUT, 2013). 

It should be noted that the first paragraph of DCAS-TKBS-0010, section 4.0, refers to “normal” 

uranium (NIOSH, 2015, p. 5). SC&A believes that NIOSH intended for this to read “natural 

uranium.” 

4.2 External dose estimate

Section 5.0 of DCAS-TKBS-0010 (NIOSH, 2015) states that the majority of NMI workers were 

monitored for external exposures. The TBD also includes a table detailing the dosimeter type, 

manufacturer, exchange frequency, and minimum detectable sensitivity (MDS) used at NMI over 

its operational period. The TBD states that if a DR were needed for a worker who did not have 

external dosimetry records, a co-exposure dose analysis could be conducted, or overestimating or 

underestimating assumptions should be used to estimate external dose. 

4.2.1 SC&A’s comments

SC&A reviewed section 5.0 of DCAS-TKBS-0010 (NIOSH, 2015). SC&A agrees with NIOSH 

that any available external dosimetry records should be used for a given DR. SC&A also agrees 

with NIOSH’s position to use overestimating or underestimating assumptions to assign external 

dose in a DR if the worker did not have external monitoring records from NMI. However, SC&A 

has several concerns as discussed in the following observations.

Observation 3: Missing guidance on the energy ranges for assigned doses

SC&A noticed that DCAS-TKBS-0010 (NIOSH, 2015) does not provide guidance on the energy 

ranges to use for assigning doses. SC&A assumes 30–250 kiloelectron volt (keV) photons are 

appropriate but believes the document would benefit from the addition of this information. 

Observation 4: SC&A is unable to verify the minimum detectable sensitivities in table 1 of 

DCAS-TKBS-0010

Table 1 of DCAS-TKBS-0010 includes dosimetry information such as providers, time periods, 

exchange frequency, and MDS. SC&A reviewed several Site Research Database (SRDB) 
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documents containing dosimetry records spanning the operational period of NMI and was not 

able to verify all of the MDS values listed in table 1 of DCAS-TKBS-0010 (NIOSH, 2015). 

Table 1 of this report compares the MDSs in DCAS-TKBS-0010, table 1, and the SRDB 

documents SC&A reviewed, including the minimum sensitivities given in those documents, if 

specified. 

Table 1. Comparison of dosimetry data in TBD table 1 and SRDB documents

TBD table 1 

period of 

use

TBD table 1 

MDS (mrem)

Reviewed 

SRDB 

document

numbers

Time period 

covered in 

SRDB 

document

MDS listed in

SRDB 

document

Minimum 

reported dose 

in SRDB 

document

10/1/1958–

10/26/1959

10 mrem 

(deep)

25035 1958–1959 10 mR (not 

specified deep 

or shallow)

10 mR 

(gamma); 

10 mrad (beta)

10/26/1959–

5/1/1961

10 mrem 

(skin); 5 mrem 

(deep)

25028; 28468 1960–1961 10 mR 

(gamma); 

10 mrad (beta)

10 mR 

(gamma); 

10 mrad (beta)

5/1/1961–

2/7/1968

10 mrem 

(deep)

25038; 25037; 

25045

1961–1962;

1963–1965; 

1966–1967

5 mrem for 

gamma 

<175 keV and 

10 mrem for 

“hard” gamma 

and beta

5 mrem 

(gamma); 

10 mrem (beta)

2/7/1968–

12/31/1983

10 mrem 

(skin); 

40 mrem 

(deep)

25040, 25093 1968–1969; 

1983

10 mrem 

(gamma); 

40 mrem (beta) 

10 mrem 

(gamma); 40

mrem (beta)

1/1/1984–

12/31/1990

10 mrem 

(skin); 

10 mrem 

(deep)

25042; 113140 10–12/1984;

1–6/1988

10 mrem 

(gamma); 

40 mrem (beta)

10 mrem 

(deep); 

10 mrem 

(shallow)

Observation 5: Additional clarification needed regarding shallow and deep dose for post1983 dosimetry records

In 2019, SC&A reviewed a DR for a former NMI employee as part of the 25th set of dose 

reconstruction reviews (Tab 503). SC&A noted that starting in 1983, the reported shallow dose 

included deep dose in the dosimetry records. As part of the issue resolution for this case, NIOSH 

indicated that SC&A correctly assumed that the deep dose was reported with the shallow dose in 

dosimetry records beginning in 1983, and that NIOSH would provide additional instructions to 

health physicists conducting DRs for NMI. SC&A recognizes that the TBD was written before 

the DR was reviewed but reiterates our concern again to ensure that the issue is not lost 

following the Cybersecurity Modernization Initiative. SC&A believes the TBD would benefit 

from the inclusion of this information. 

Section 5.2.2.3 of the petition evaluation report for SEC 195 (NIOSH, 2012) states that neutron 

monitoring was not performed at NMI, but that the potential for neutron exposure from α,n 

reactions with light elements, interactions with oxides, and spontaneous fission existed. The 

petition evaluation report further states in section 7.3.1.1 that if unmonitored neutron dose needs 

to be assigned for a given DR, ORAUT-OTIB-0024, revision 00 (ORAUT, 2005), should be 
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used. However, SC&A did not identify any discussion of external neutron dose in DCAS-TKBS0010 (NIOSH, 2015). This issue has been discussed at length with the Board for other facilities. 

Since the potential neutron doses are small in comparison to the photon dose and photon 

assumptions are overestimating, additional consideration of neutron doses may not be needed. 

However, SC&A maintains that the issue of neutron dose, even if negligible, should be included 

in the TBD.

Observation 6: Discussion needed on the presence of industrial radiography at the site 

and potential doses to workers

SC&A reviewed an SRDB document containing registration information for two industrial x-ray 

machines that were kept at the site (Nuclear Metals, 1955–1966, PDF p. 46). According to the 

document, they were used at the site for “x-ray of metal specimens and parts.” SC&A believes 

the TBD would benefit from a discussion of the potential external extremity dose to workers 

from industrial radiography used at the site.

4.3 Residual period internal dose estimate

Section 6.0 of DCAS-TKBS-0010 (NIOSH, 2015) discusses the potential worker internal 

exposure to residual contamination after U.S. Department of Energy operations ended. NIOSH 

used the highest uranium intake rate from OTIB-0084 (ORAUT, 2013) of 574 picocuries per day

(pCi/day) along with the guidance of Battelle-TBD-6000 (NIOSH, 2011) to calculate a uranium 

surface contamination value of 169,700 picocuries per square meter (pCi/m2). NIOSH then used 

this surface contamination value with a resuspension factor of 1E-05 per meter (m-1) to derive 

the estimated resuspended airborne uranium concentration of 1.7 picocuries per cubic meter

(pCi/m3), which results in a uranium inhalation intake rate of 11.2 pCi/day at the beginning of 

the residual period. NIOSH did not calculate uranium ingestion because the uranium 

contamination values from OTIB-0084 came from urinalysis samples. 

To estimate thorium intake during the residual period, NIOSH used NMI’s thorium 

contamination guideline of 5,000 disintegrations per minute per 100 square centimeters 

(dpm/100 cm2) total alpha activity, as NIOSH did not have thorium contamination or bioassay 

data. This value was divided by 3 to account for the other alpha-emitting radionuclides in the 

thorium (Th)-232 decay chain. NIOSH calculated the resuspended airborne concentration and 

then a Th-232 inhalation rate of 11 disintegrations per minute per day (dpm/day). The Th-232 

ingestion rate of 100.5 dpm/day was calculated using the surface contamination value and a rate 

of 1.1E-4 square meters per hour (m2/hr). The inhalation and ingestion intakes are assigned for 

each of the five radionuclides in the decay series (Th-232, radium (Ra)-226, actinium (Ac)-228, 

Th-228, and Ra-224). 

The intake rates from uranium inhalation, thorium inhalation, and thorium ingestion were 

decreased each year of the residual period to account for depletion of the contamination using 

ORAUT-OTIB-0070, revision 01 (ORAUT, 2012). 

4.3.1 SC&A’s comments

SC&A reviewed the calculations in section 6.0 of DCAS-TKBS-0010 (NIOSH, 2015) for 

internal dose from residual contamination. SC&A agrees with NIOSH using the highest uranium 

intake rate from OTIB-0084 (ORAUT, 2013), but we did not review NIOSH’s analyses and 
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calculations to generate that intake rate. SC&A confirmed NIOSH’s calculation of an airborne

uranium concentration of 87.3 pCi/m3 for the start of the residual period, assuming the intake 

rate of 574 pCi/day is from inhalation for 2,000 hours per year, normalized per calendar day. 

Using the assumed uranium air concentration of 87.3 pCi/m3 and the methodology from BattelleTBD-6000, SC&A also calculated a uranium surface contamination level of 169,711 pCi/m2

, 

which closely matches NIOSH’s value. Assuming a resuspension rate of 1E-05 m-1, SC&A 

calculated the airborne uranium concentration to be 1.7 pCi/m3

. Assuming inhalation for 2,000 

hours per year and normalized over 365 days per year, SC&A calculated a uranium inhalation 

intake rate for the start of the residual period to be 11.2 pCi/day, which matches NIOSH’s 

calculations. SC&A agrees that since these calculations were based on urinalysis data, uranium 

ingestion does not need to be calculated separately. 

SC&A agrees that in the absence of thorium bioassay data, using the site’s thorium 

contamination limit of 5,000 dpm/100 cm2 for residual period internal dose calculations is 

reasonable. SC&A also agrees with dividing this value by 3 since the thorium contamination 

limit is for total alpha, and there are three alpha decays in the thorium decay chain. Assuming a 

resuspension rate of 1E-05 m-1, 2,000 hours per year of exposure, and normalizing over 365 days 

per year, SC&A calculated a thorium inhalation intake rate of 11 dpm/day at the beginning of the 

residual period, which matches NIOSH’s value. Using the ingestion rate of 1.1E-4 m2/hr from

NUREG/CR-5512 (NRC, 2001), SC&A also matched NIOSH’s calculated thorium ingestion rate 

at the beginning of the residual period of 100.5 dpm/day. The inhalation and ingestion intakes 

should be assigned for each of the five radionuclides in the decay series. 

SC&A also confirmed the values in DCAS-TKBS-0010, table 3 (NIOSH, 2015), using table 4-2 

of ORAUT-OTIB-0070 (ORAUT, 2012) to account for source term depletion over time during 

the residual period for uranium inhalation, thorium inhalation, and thorium ingestion. 

Observation 7: Discussion needed on the potential for overtime at the site

SC&A notes that the calculations for internal and external dose during the residual period are 

based on the assumption that workers may have been exposed for 2,000 hours per year. If 

workers may have routinely worked in excess of 40 hours per week, it may be appropriate to 

adjust the residual period internal and external dose estimate calculations accordingly.

4.4 Residual period external dose estimate

NIOSH used the calculated uranium surface contamination value of 169,700 pCi/m2 with the 

uranium dose conversion factors from Battelle-TBD-6000 (NIOSH, 2011) to estimate the 

external dose rates from residual uranium contamination. Assuming workers were exposed for 

2,000 hours per year, this resulted in dose rates of 0.3 millirem per year (mrem/yr) photon and 

28.8 mrem/yr beta.

NIOSH also estimated the external dose rate from residual thorium contamination using the 

assumed thorium total alpha activity surface contamination level of 5,000 dpm/100 cm2 and the 

dose conversion factors in U.S. Environmental Protection Agency (EPA) Federal Guidance 

Report (FGR) No. 12 (EPA, 1993). Assuming workers were exposed for 2,000 hours per year, 

this resulted in dose rates of 1.9 mrem/yr photon and 9.6 mrem/yr beta.
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4.4.1 SC&A’s comments

SC&A reviewed the calculations in section 6.0 of DCAS-TKBS-0010 (NIOSH, 2015) for 

external dose from residual uranium contamination. SC&A was able to match NIOSH’s 

calculated external photon and beta dose from residual uranium contamination using the dose 

conversion factors from table 3.10 of Battelle-TBD-6000 (NIOSH, 2011), the uranium surface 

contamination value of 169,700 pCi/m2, and assuming exposure for 2,000 hours per year. 

SC&A noted that NIOSH used the dose conversion factors from Battelle-TBD-6000 (NIOSH, 

2011) for surface contamination from natural uranium. DCAS-TKBS-0010 (NIOSH, 2015) states 

that NMI used depleted uranium in addition to nature uranium toward the end of operations. 

Although NIOSH did not consider depleted uranium during the residual period, SC&A considers 

the use of natural uranium throughout the residual period to be an efficiency measure, which 

results in a higher dose.

The residual Th-232 concentration is assumed to be 1,666.67 dpm/100 cm2 and is assumed to be 

equal to the residual concentration for Ra-226, Ac-228, Th-228, and Ra-224. SC&A verified that 

NIOSH used the contaminated ground surface effective and skin dose coefficients from FGR 12 

(EPA, 1993) and assumed an exposure of 2,000 hours per year. SC&A was able to match 

NIOSH’s calculated external photon and beta dose rates from residual thorium contamination. 

4.5 Occupational medical dose estimate

No site-specific guidance for NMI occupational medical dose exists; therefore, the TBD 

(NIOSH, 2015) says to use the guidance in ORAUT-OTIB-0006, revision 04 (ORAUT, 2011), 

for assigning occupational medical dose in DRs. It is assumed that employees received preemployment, annual, and termination x-rays during NMI’s operational years. No occupational 

medical dose is assigned during the residual period. Organ doses due to occupational medical 

exposure are entered in the Interactive RadioEpidemiological Program (IREP) as 30–250 keV 

photons as a normal distribution with a standard deviation of 30 percent. 

4.5.1 SC&A’s comments

SC&A reviewed section 7.0 of DCAS-TKBS-0010 (NIOSH, 2015) and agrees with the guidance 

to use ORAUT-OTIB-0006, revision 04 (ORAUT, 2011), and the assumed x-ray frequency to 

calculate occupational medical doses.

1

 

1 SC&A notes that this version of ORAUT-OTIB-0006 has since been superseded by revision 06 (ORAUT, 

2019).
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5 Subtask 3: Evaluate the PER’s Stated Approach for Identifying the 

Number of DRs Requiring Reevaluation of Dose

5.1 NIOSH’s selection criteria

Section 3.0 of DCAS-PER-070 (NIOSH, 2016) described the following criteria NIOSH used to 

identify previously completed claims requiring reevaluation using DCAS-TKBS-0010 (NIOSH,

2015).

• NIOSH identified all previously completed claims with verified employment at NMI that 

had a POC of less than 50 percent. This identified 21 claims. 

• Three of these claims had already been completed using DCAS-TKBS-0010 (NIOSH, 

2015) and were removed from further evaluation. 

• The remaining 18 claims have been reevaluated by NIOSH using DCAS-TKBS-0010

(NIOSH, 2015), as well as other applicable approved DR methods. 

Following reevaluation, 16 claims had a new POC below 45 percent, and 2 claims had a new

POC between 45 percent and 50 percent. NIOSH ran IREP 30 times at 10,000 iterations for these 

two claims, and the resulting POC was still below 50 percent for both claims.

5.2 SC&A’s comments

SC&A finds NIOSH’s selection criteria for defining the 18 claims requiring reevaluation of dose

to be sufficient to identify all impacted claims. Additionally, SC&A believes the PER was 

conducted in a timely manner, as the TBD was issued in April 2015, and DCAS-PER-070 was 

issued in April 2016. There are no findings associated with subtask 3.
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6 Subtask 4: Conduct Audits of a Sample Set of Reevaluated DRs 

Mandated by DCAS-PER-070

Previous sections of this report described the issuance of DCAS-TKBS-0010 (NIOSH, 2015), the 

TBD for NMI. SC&A previously reviewed Tab 503 as part of the 25th set of DR reviews. SC&A 

confirmed with NIOSH that this case was among the 16 claims reevaluated with a revised POC 

less than 45 percent.

2

2 SC&A reviewed a subsequent revision of the claim with a higher POC.

 SC&A recommends that the Board select one case from the remaining 

cases evaluated by NIOSH. SC&A believes one of the claims that resulted in a POC between 

45 and 50 percent would be appropriate for evaluation. 
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7 References

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