Page 1 of 19

This working document was prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or ABRWH 

(or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary positions 

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that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

White Paper on NUMEC Issues and Feasibility of 

Coworker Model

Rev. 0 

National Institute for Occupational 

Safety and Health 

June 23, 2016

Lara Hughes, Ph.D., CHP

Research Health Scientist

National Institute for Occupational Safety and Health

Division of Compensation Analysis and Support
Page 2 of 19

This working document was prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or ABRWH 

(or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary positions 

taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any information 

that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Introduction:

The NIOSH Special Exposure Cohort (SEC) evaluation reports (SEC-00080 and SEC-00108) for the Nuclear 

Materials and Equipment Corporation (NUMEC) facilities in Apollo and Parks Twp. PA (hereafter referred 

to as NUMEC), concluded that it was not possible to plausibly bound internal and external doses at these 

facilities. The entire operational period for both NUMEC sites have been added to the SEC based on 

internal and external infeasibility (with some exceptions, which are elaborated below). An evaluation of 

the NUMEC Technical Basis Document (TBD) by Sanford Cohen & Associates, issued in April of 2013,

resulted in 21 findings that were discussed during a meeting of the work group on Uranium Refining 

Atomic Weapons Employers of the Advisory Board on Radiation and Worker Health on August 3, 2015. 

At that meeting 10 of the 21 findings were closed, pending NIOSH incorporating the agreed upon 

changes into the revised site profile. 

NIOSH has evaluated the remaining issues from the Work Group Discussion for NUMEC and has 

proposed the following updates to the issue resolution status. The revised NUMEC TBD (ORAUT-TKBS0041, Rev. 03-B) has a tentative publication date of 8/12/2016 and is currently in draft status. 

NIOSH does not expect any additional data capture for NUMEC to be feasible given the difficulties 

working with the contractor before. NIOSH made a large data capture effort in 2014, which involved the 

collection of over 14000 documents after many months of negotiation. 

Status of Findings: 

Finding 1: Clarification is needed regarding the start and end dates of Parks Township Site operations. 

Proposed NIOSH resolution: Tables will be updated with new information and values possibly 

corrected. 

August 2015 WG discussion: Closed, if change is included in TBD revision. 

NIOSH update June 2016: Change included in draft ORAUT-TKBS-0041 Rev. 03-B. 

Finding 2: The site profile should provide guidance about what level of uranium enrichment should be 

assumed for those urine bioassay results that are expressed in units of μg/L.

Proposed NIOSH resolution: NIOSH will add a section to TBD with guidance on enrichment 

assumption if no other information is available (assume highly enriched since it is claimant 

favorable and was used at Apollo).

August 2015 WG discussion: Closed, if guidance is included in TBD revision. 
Page 3 of 19

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or ABRWH 

(or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary positions 

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that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

NIOSH update June 2016: Change included in draft ORAUT-TKBS-0041 Rev. 03-B. 

Finding 3: Some guidance is needed on how to perform dose reconstructions prior to 1959, and what 

approach to use for missed and unmonitored exposures.

Proposed NIOSH resolution: None. Pre-1959 dose reconstruction is infeasible per SEC.

August 2015 WG discussion: Closed. 

Finding 4: Uranium inhalation recommendations for the Apollo Site need to consider the method 

discussed by Davis and Strom (2008) for dealing with uncertainties in DWE. This technique was 

evaluated and found to be appropriate in the site profile review for the Fernald Feed Materials 

Production Center (Fernald).

Proposed NIOSH resolution: Davis and Strom (2008) evaluated several HASL reports and 

concluded that the daily weighted exposures have a lognormal distribution with a geometric 

standard deviation of 5. HASL data is available for the Apollo site and has been used to evaluate 

exposure concentrations. As discussed in Finding 18, the air concentration used for the 

beginning of the residual period has been re-evaluated and is now based on General area (GA) 

monitoring rather than daily weighted average exposures (see response to Findings 5 and 18 

below). The geometric standard deviation (GSD) for the revised air concentrations has been set 

to 5.0 based on Davis and Strom (2008).

August 2015 WG discussion: The discussion during the work group meeting moved from the 

question of using the HASL data in dose reconstructions to the more general issue of whether it 

was possible to develop co-worker models for uranium intakes. Based on the Apollo Evaluation 

Report, internal doses from uranium bioassay can be reconstructed when data are available for 

an individual claim. SC&A questioned if NIOSH has any claims with uranium bioassay where

internal uranium dose was not assigned. SC&A would like to investigate more to find workers 

who were exposed to U and not had internal U assigned. NIOSH was tasked to review and 

evaluate if a coworker model is needed. Issue 4 was closed; however, NIOSH committed to 

assess the possibility of a coworker model. Dr. Neton pointed out that the SEC decision does not 

mean that every single feasibility and infeasibility was evaluated (meaning, just because the 

finding for the Apollo ER was that internal uranium dose reconstruction are feasible when data 

exist for a given claim does not necessarily mean that a coworker model can be developed for 
Page 4 of 19

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or ABRWH 

(or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary positions 

taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any information 

that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

this data). Any coworker model that is developed would have to hold up to the standards of the 

coworker implementation guide.

NIOSH update June 2016: During the initial discussion, there was some misunderstanding in 

NIOSH’s part on the focus of this issue. The original issue addresses Section 5.4 of the TBD, 

which provides guidance to assign internal doses based on fixed BZ air data for uranium workers 

during 1959-1961. Upon further consideration of the guidance and the data, this section using 

HASL BZ data will now be removed from the TBD in accordance with the findings presented in 

the Apollo SEC evaluation report that internal doses cannot be reconstructed during that time 

period except when uranium bioassay are available. HASL BZ data were collected for specific 

projects and operators during a limited operating time and do not reflect the range of uranium 

activities carried out and NUMEC. 

As for the coworker model discussion, it is not expected that the available data can be used to 

develop coworker models that would adhere to the guidelines expected from such a model. 

Please see detailed analysis below. 

Finding 5: Inadequate information is given to replicate NIOSH’s determination of median inhalation 

concentration of uranium. The NIOSH result could not be replicated, and it appears that relevant 

information has been omitted from the HASL studies reported in Appendix A to the site profile.

Proposed NISOH resolution: No data from the HASL reports cited have been omitted, but the

calculation approach has been revised since the previous TBD was issued and is now based on 

GA data. 

August 2015 WG discussion: NIOSH should provide more guidance how the revised approach is 

to be used for partial dose reconstructions. This analysis was done to get to a starting point for 

levels to be used in the residual period. For the operational period, BZ samples are used if they 

are available. SC&A voices concerns that there were significantly higher intakes in the ceramics 

plant than other areas and whether those would be represented in the median intakes. 

NIOSH update June 2016: See response to Finding 4.

Finding 6: The site profile would benefit from a discussion demonstrating that the Hanford fuel-grade 

mix, as opposed to the weapons-grade or commercial-grade plutonium, is limiting for the full range of 

plutonium mixes and ages that were used at NUMEC. In addition, given the complexity of this subject, a 

review of actual dose reconstructions would provide greater insight into how this matter is actually 

being addressed.
Page 5 of 19

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or ABRWH 

(or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary positions 

taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any information 

that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Proposed NISOH resolution: Table will be updated with recently captured information on the 

fuel types used at NUMEC to represent more accurately the mixes that were handled. 

August 2015 WG discussion: SC&A wants to review response in detail and provide comment on 

the response. SC&A was tasked with providing an additional response.

SC&A response after WG discussion: Other possible Pu mixes that may have been present at 

NUMEC should be investigated (such as Japanese fuels and fuels from the UK). 

NIOSH update June 2016: This issue was not pursued further. Additional data capture is not 

considered to be a productive option for NUMEC. The currently available data can be used for a 

reasonable claimant-favorable assumption to assign partial internal dose. It would not be 

reasonable to speculate on additional Pu mixtures to complete partial dose reconstructions for 

non-presumptive cancers. Any reported Pu bioassay will be used at face value. No adjustments 

for other contaminants are available.

Finding 7: The MDAs for Am-241 lung counting are very low, and the counting method should be further 

explored in order to give them credibility.

Proposed NIOSH resolution: NIOSH will added some additional guidance to the draft TBD. 

August 2015 WG discussion: NIOSH has addressed some of the MDA issues and added some 

more reasonable values, but SC&A’s concerns remain. Dr. Neton agrees in that the MDA

numbers for Pu look somewhat low, the Am MDA looks ok. The Pu MDA values are very much 

dependent on chest wall thickness. SC&A was tasked with providing additional assessment. 

SC&A response after WG discussion: SC&A believes that the MDA value for in-vivo monitoring 

of Am-241 and Pu-239 are not reliable, that very limited data is available, and that the low 

reported values for MDAs for Am-241 in-vivo lung monitoring need to be further developed. The 

values for Pu-239 are not credible, due to the 17 keV X-rays being measured directly.

NIOSH update June 2016: NIOSH has discussed and evaluated the chest counting data that was 

supplied by Babcock and Wilcox. Many of the reported results have a reported MDA when a 

non-detectable amount is reported. The MDAs appear to be lower than what might be reported 

today, but it would be difficult to come up with an alternate value. Most measurements were 

done at the University of Pittsburg and the NUMEC in-vivo program was overseen by a person 

who was highly regarded in the field. The lower MDAs could be the result of the calibration 

phantoms used at the time. Until the advent of the Livermore realistic phantom in the late 

1970’s, the phantoms in use did not provide a sophisticated representation of human anatomy 
Page 6 of 19

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(or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary positions 

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that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

and tissue equivalency. It was eventually discovered that the earlier phantoms tended to 

overestimate counting efficiency, especially for low-energy emitters like Pu and Am. 

Unfortunately, there does not seem a straightforward way to adjust the earlier values

retroactively, to comport with what might be reported today. 

There are too many unknown variables involved, including the exact design and configuration of 

the detectors used, the position of the detectors over the lungs (i.e., measurement geometry), 

and the chest wall thickness (CWT) for each subject counted. Even if the CWT is known for a 

person, the manner in which it was measured or calculated can lead to large differences in the 

value. Given all this, NIOSH intends to use the detection limits as reported for each original 

measurement. While there may be some negative bias associated with using these values, it 

seems to that this is preferable to making adjustments that would largely be based on 

conjecture. This approach would be consistent with performing partial dose reconstructions for 

non-presumptive cancers using “data that may be included in an individual’s file (and that can 

be interpreted using existing NIOSH dose reconstruction processes or procedures)” to support a 

partial internal dose reconstruction for non-presumptive cancers and/or cases that have less 

than 250 working-days of employment.

Finding 8: The site profile would benefit from a more thorough discussion of the possible use of air 

sampling data to reconstruct internal plutonium exposures and to take into consideration the additional 

data provided by Crosby 1967 and NUMEC 1967.

Proposed NIOSH resolution: None. Internal dose reconstructions are partial and done only in 

cases where bioassay is available.

August 2015 WG discussion: Closed.

Finding 9: It does not seem appropriate to use ORAUT-OTIB-0054 (ORAUT 2007a) to reconstruct the 

internal exposures of workers at NUMEC who might have been exposed to mixed fission products. 

ORAUT-OTIB-0054 states that its guidance “does not apply to determination of intakes where 

radionuclides have been purposely extracted and concentrated as for heat generation sources, medical 

uses, or waste handling operations that caused significant alteration to the source term to which 

workers were exposed.” For example, see Table 5-1 of the site profile. Also, the fission product mix 

given in ORAUT-OTIB-0054 does not contain the same radionuclides as the fission product mixes given 

for the NUMEC Laundry in the 1975 effluent release report (SRDB #20081) and for in-vivo count results 

in SRDB #19970. The NUMEC mixes include Co-60, which the ORAUT-OTIB-0054 mix omits.
Page 7 of 19

This working document was prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or ABRWH 

(or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary positions 

taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any information 

that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Proposed NIOSH resolution: The use of OTIB-0054 (ORAUT 2015) is appropriate when the source 

of activity is from reactors. As indicated in this finding, the NUMEC laundry processed materials 

from many sources in addition to the commercial reactor laundry. The site profile will be 

modified to remove guidance on use of OTIB-0054 for evaluation of dose from associated fission 

products and activation products. The guidance will indicate that doses are to be evaluated only 

for the radionuclides included in the bioassay results

August 2015 WG discussion: Closed, if new guidance is included in TBD revision. 

NIOSH update June 2016: Change included in draft ORAUT-TKBS-0041 Rev. 03-B. 

Finding 10: Internal dose reconstructions performed for NUMEC personnel might need to be revisited in 

light of changes to the Fernald site profile (ORAUT 2004) with respect to RU. Also, additional direction is 

needed with respect to which workers or operations should be assigned RU intakes.

Proposed NIOSH resolution: Some language will be added to the revised NUMEC TBD regarding 

assigning RU doses for NUMEC.

August 2015 WG discussion: Discussed whether any additional sources of information regarding 

the uranium composition were reviewed. Closed if NIOSH adds guidance on assigning RU doses 

to the TBD revision. 

NIOSH update June 2016: Change included in draft ORAUT-TKBS-0041 Rev. 03-B. 

Finding 11: NIOSH should explain whether the concerns expressed in the Pantex site profile (ORAUT 

2007d) about the Helgeson chest count data might also apply to chest count data at NUMEC performed 

by Helgeson for NUMEC workers.

Proposed NIOSH resolution: The in vivo counting at NUMEC was performed by Helgeson only 

during 1968, 1971, and once in 1975. The Helgeson counts included primarily plutonium-239, 

with a few results for uranium and fission products. The majority of in-vivo counting was 

performed at the University of Pittsburg hospital. The issue with Pantex was that the counts for 

uranium were biased high and represented false positives (Brake 1989). The current Pantex 

internal dose TBD has eliminated all reference to Helgeson in-vivo measurements. Using the 

Helgeson results for uranium at NUMEC is favorable to the claimant, because any bias would be 

high. There was no issue identified related to Helgeson in-vivo counting for fission products, 

plutonium, or americium. 
Page 8 of 19

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or ABRWH 

(or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary positions 

taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any information 

that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

August 2015 WG discussion: SC&A wants to look into this issue more. SC&A will review the issue 

and provide findings to NIOSH.

SC&A response after WG discussion: SC&A remains concerned about the values used for MDA 

for in-vivo counts, as some are listed as 63 μg and some are listed as 80 μg for U-235. SC&A

would like to see clarification and DR examples to ensure the correct value is used.

NIOSH update June 2016: NUMEC used the Helgeson mobile whole body counter for Pu and Am 

counts, and also some U-235. The MDA reported for U-235 in 1968 using the Helgeson unit is 80 

μg. NUMEC mostly did whole body counts at the Low Level Radiation Monitoring Facility at the 

University of Pittsburg, which, on many count results, report a MDA value of 63 μg for U-235. A 

clarifying statement could be added to the TBD, but since generally the MDAs seem to be 

reported with the respective result, for a non-presumptive cancer, the MDA respective to the 

analysis would be used. As outlined for item 7, NIOSH has not located any information that 

would allow for a critical assessment and correction of reported MDA values that are perceived 

low by SC&A. The issue with Pantex was that the counts for uranium were biased high and 

represented false positives (Brake 1989). The current Pantex internal dose TBD has eliminated 

all reference to Helgeson in vivo measurements. Using the Helgeson results for uranium is not 

to the detriment to the claimant, since it would lead to a positive bias. No additional research is 

proposed at this point by NIOSH.

Finding 12: Table 6-2 and the associated text in Section 6.3.2 of the site profile should be reviewed and 

modified as needed to correct any oversights, inconsistencies, or errors.

Proposed ORAU resolution: The indium foil criticality dosimeters were not included in Table 6-2 

because they were not used for routine workplace exposures. They were included only to 

determine dose from a criticality in the event that a criticality occurred. No criticality incidents 

were reported at the NUMEC facilities. The text was reviewed as suggested and the information 

in the text is consistent with information provided in Tables 6-2 and 6-3.

August 2015 WG discussion: SC&A insists there is still an error in the table. How are data from 

multi component badges handled? SC&A to elaborate further.

SC&A response after WG discussion: More information is needed regarding how the data from 

the neutron detection devices will be used to reconstruct neutron doses. For example, Table 6-2 

describes the method for deriving the fast neutron dose that involved subtraction of the 

thermal dose, but it is not clear if this was determined from a cadmium-filtered film badge or 

not. The Landauer “Z1” dosimeter contains a neutron sensitive CR-39 component, but this is not 
Page 9 of 19

This working document was prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or ABRWH 

(or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary positions 

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that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

mentioned in the table or text. Both the text and table are unclear and inconsistent regarding 

the use of CR-39. Table 6.2 indicates that Z1 badges are used (for beta/gamma), but nowhere 

does it say that they contain a CR-39 neutron component. The text in section 6.3.2 mentions the 

use of NTA, then states that, after 1968, neutron monitoring was performed with TLDs. Table 6-

2 does say that other types of neutron dosimeters (not mentioned in the body of the text) did 

contain CR-39 components. NIOSH needs to revisit this section and ensure that both the table 

and text agree with each other and with the dosimetry practices of the period

NIOSH update June 2016: The available guidance is suitable for assigning neutron doses for

partial dose reconstruction of external neutron dose. NIOSH will clarify any outstanding 

questions from SC&A during the upcoming work group discussion. 

Finding 13: Given our understanding that it is NIOSH’s position that external exposures at the Parks 

Township Site can be reconstructed with sufficient accuracy, it appears that the description of the 

sources and circumstances responsible for external exposures need to be better developed, if possible.

Proposed NIOSH resolution: External dose can be evaluated only when dosimetry records exist. 

There was one dosimetry department for all NUMEC facilities that provided dosimetry for both 

the Parks Township and Apollo facilities. The limitations stated for the Apollo facilities also 

apply to the Parks Township facilities (see response to Finding 16).

August 2015 WG discussion: NIOSH to issue response on whether an external coworker model 

is feasible. 

NIOSH update June 2016: It is not expected that the available data can be used to develop a 

coworker model that would adhere to the guidelines expected from such a model. Please see 

detailed analysis below.

Finding 14: The site profile should provide justification for why adjustment factors are not required for 

neutron exposures estimated using nuclear track emulsion Type A (NTA) film, considering that it appears 

that the neutron energy spectrum likely extended to well below 1 mega-electronvolt (MeV). For 

example, Table 6-8 of the site profile indicates that the energy range of neutron exposures extended 

from 0.1 to 2 MeV. 

Proposed NIOSH resolution: A n:p approach was developed from available data. 
Page 10 of 19

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or ABRWH 

(or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary positions 

taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any information 

that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

August 2015 WG discussion: SC&A states that NIOSH response is thorough, but is not sure it 

makes technical sense. SC&A is to provide a response after additional review. 

SC&A response after WG discussion: While the n/p methodology that NIOSH is proposing for 

NUMEC has been used at other AWE and DOE sites, the dose data used to derive the n/p values 

suggested by NIOSH for NUMEC are not comprehensive or robust. NIOSH may want to consider 

adopting a bounding n/p ratio that ensures that the neutron doses are not understated for 

circumstances where the available n/p data are limited.

NIOSH update June 2016: NIOSH has reviewed the suggested approach, and agrees that the data 

are limited; however, NIOSH is not aware of any additional data that may exist and that would 

allow for refining the currently proposed approach in any way. The proposed approach was 

included in draft ORAUT-TKBS-0041 Rev. 03-B. 

Finding 15: The markedly different photon energies associated with the operations at NUMEC would 

indicate the possible need for adjustment factors for the results of film badge dosimeters, which are not 

provided in the site profile.

Proposed NIOSH resolution: Film badge dosimeters, while over responding to radiation recorded 

in the open window, may under respond to low energy photons (16 keV and 59 keV photons are 

a particular concern) (Wilson et al. 1990). Although the films and filters at NUMEC were 

different than the dosimeters discussed in the reference, a reasonable comparison between the 

film dosimeters is expected (AEC 1955). The site acknowledged this deficiency in a 1966 report 

(Caldwell and Judd 1966) and made corrections to the dosimetry to account for this under 

response. Prior to the report being issued (i.e. prior to 1966), to account for under response of 

film dosimetry to low energy photons, the result in the open window should be assigned as <30 

keV photons for workers at plutonium facilities while the deep dose response is assigned in 

accordance with the worker location.

August 2015 WG discussion: Auger electrons are very low energy and would not penetrate skin; 

therefore, part of NIOSH response does not address issue. Also, do we assign these low energy 

betas for all alpha emitters at other sites? NIOSH wants to check this answer and get back, but 

WG decided that this is an SC&A action item for now – SC&A is to provide additional information 

on this finding.

SC&A response after WG: NIOSH concurred that the site profile needs to be revised to account 

for possible over- and/or under-responses of dosimeters under some circumstances. The 

decision to modify the site profile approach for situations where low-energy photons and betas 
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(or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary positions 

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are present seems appropriate by assuming <30 keV photons for plutonium workers for open 

window results. However, NIOSH should endeavor to gather more information on the differing 

film badges and the protective coverings to enable a better assessment of situations where lowenergy photons or betas were under-reported or missed entirely.

NIOSH update June 2016: The initially proposed guidance was added to the draft ORAUT-TKBS0041 Rev. 03-B. Additional data capture is considered to be unproductive, but additional review 

in available NUMEC files continues. 

Finding 16: NIOSH should consider developing a universal coworker model based on NUMEC claimant 

records, or specify a more consistent basis for assigning external doses beyond the medical x-rays 

associated with the site.

Proposed NIOSH resolution: A coworker model for non-presumptive claims is not expected to be 

feasible.

August 2015 WG discussion: NIOSH is tasked to do a formal review to see if a coworker model is 

feasible.

NIOSH update June 2016: It is not expected that the available data can be used to develop a 

coworker model that would adhere to the guidelines expected from such a model. Please see 

detailed analysis below. 

Finding 17: The site profile should include guidance for deriving non-penetrating doses to skin and other 

organs from beta emitters associated with surface contamination during the residual period.

Proposed NIOSH resolution: Additional information was included in the draft of the revised TBD.

August 2015 WG discussion: Closed. 

Finding 18: General air (GA) samples, as opposed to breathing zone (BZ) samples, should be used as the 

starting point for reconstruction of radionuclide intake rates during the residual period.

Proposed NIOSH resolution: The air concentration value that is favorable to claimants to use for 

the residual period is represented by the maximum median value of 222 dpm/m3. The maximum 

estimated GSD for all data sets is 6.95 for the HASL GA data. Therefore, the residual activity will 
Page 12 of 19

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or ABRWH 

(or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary positions 

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that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

be based on a lognormal distribution with a median of 222 dpm/m3 and a GSD of 5.0. This 

represents a slight increase in median air concentration from the previous concentration of 210 

dpm/m3 and GSD of 7.91.

August 2015 WG discussion: Some BZ samples are higher than some of the GA samples. Why is 

that? Possibly there are some process samples that were added to the GA sample set. The data 

need to be reviewed to make sure there are no inconsistencies. 

NIOSH update June 2016: The data were reviewed and corrected if necessary and the revised 

approach was included in draft ORAUT-TKBS-0041 Rev. 03-B. The results from these 

measurements and the HASL reports indicate an air concentration value that is favorable to 

claimants to use for the residual period is represented by the maximum median value of 329

dpm/m3

. 

Finding 19: SC&A recommends that NIOSH use a resuspension factor of about 1E-5 per meter to 

derive the airborne dust loading for the beginning of the residual period, or perhaps simply assume 

that the average general air dust loading observed during the operational period is applicable to the 

beginning of the residual period. 

Proposed NISOH resolution: Resuspension factor for Apollo was changed, but not for Parks, 

because of cleanup activities.

August 2015 WG discussion: Closed, if the guidance is included in the TBD revision.

NIOSH update June 2016: The change was included in draft ORAUT-TKBS-0041 Rev. 03-B. 

Finding 20: The site profile makes no reference to radionuclides other than uranium during the 

residual period at Apollo.

Proposed NIOSH resolution: Suggestion for adding thorium and progeny to approach.

August 2015 WG discussion: Closed, if the thorium guidance is added to the TBD revision. 

NIOSH update June 2016: The change was included in draft ORAUT-TKBS-0041 Rev. 03-B. 
Page 13 of 19

This working document was prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or ABRWH 

(or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary positions 

taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any information 

that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Finding 21: There is conflicting guidance on how aged plutonium mixtures should be treated during 

the residual period at Parks Township.

Proposed ORAU resolution: add guidance to TBD

August 2015 WG discussion: Closed, if guidance was added to the TBD revision.

NIOSH update June 2016: The change was included in draft ORAUT-TKBS-0041 Rev. 03-B. 

NIOSH position on coworker models for NUMEC to assign doses for partial dose reconstructions

During the work group meeting in August 2015, it was questioned how NIOSH assigns dose for nonpresumptive claims for the NUMEC Apollo and Parks facilities when the worker in question was 

unmonitored. Specifically in question was the approach for internal uranium at Apollo and external dose 

assignment at the Parks facility. The Apollo SEC evaluation report specifies that internal uranium dose 

reconstruction is only feasible when uranium bioassay is available. The Parks SEC evaluation report 

states that internal dose reconstruction is not feasible. The Apollo Evaluation Report also specifies that 

external doses for non-presumptive claims can be reconstructed using available external dosimetry 

data. The Parks Evaluation Report states that the external dose reconstruction feasibility was not fully 

evaluated, because the report was prepared under § 83.14.

Additional research was requested of NIOSH to evaluate if the available uranium bioassay and external 

dosimetry data are sufficient for the development of a coworker model to support the dose 

reconstruction approach for non-presumptive claims of unmonitored workers. These are the findings: 

A review of dose reconstruction approaches used after the SEC class implementation indicates that the 

guidance in the evaluation reports is followed. Those dose reconstructions are completed using 

available data such as uranium in urine, GA/BZ and external dosimetry for individual claims. When data 

is not available, doses are not reconstructed per the infeasibility decisions in the respective evaluation 

reports. As a result, for some claims only medical X-ray dose is assigned. 

Both NUMEC SEC classes were driven by several issues affecting the feasibility to reconstruct internal 

doses: 

o Internal monitoring data from 1957 through 1959 are not available. 

o Adequate information on thorium operations is not available. 

o Bioassay data from the company Controls for Environmental Pollution (CEP) is not suitable 

for use (years 1976 through 1993). 
Page 14 of 19

This working document was prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or ABRWH 

(or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary positions 

taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any information 

that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

o No monitoring data, process descriptions or source term data exist for the fabrication of RaBe and Po-Be neutron sources at both facilities. In addition, no information is available on 

the fabrication of Co-60 and Ir-192 sources at the Parks facility. 

o Potential elevated ambient radiation levels from stack releases at the Apollo plant are not 

well documented.

o Plutonium operations at the Apollo facility are not well documented. The NUMEC facility at 

Parks Township handled all plutonium processing and the available documentation does not 

indicate that major amounts of plutonium were handled at the Apollo plant. However, 

NUMEC Apollo was licensed to handle significant amounts of plutonium mostly in coated or 

encapsulated form. The laundry operations at the Apollo site had plutonium residues, 

resulting most likely from the handling of the work clothing from both NUMEC facilities. 

There is insufficient information to permit the construction of a source term model for 

plutonium at the NUMEC Apollo plant. 

o No information is available on the operations with irradiated fuel in the hot cell at the Parks 

facility. Exposures from these activities are evident from incident reports and whole body 

counting reports that show uptakes; however, the available data is insufficient to calculate 

bounding doses.

Feasibility of internal coworker model for uranium: 

Uranium was processed at both the Apollo and Parks Township site. Enrichment levels varied and 

included depleted uranium (DU), natural uranium (NU), low enriched uranium (LEU (3.5 %)) and 

highly enriched uranium (HEU (93 %)). No bioassay results are available before 1959. Data are 

available from late 1959 through 1988 and in 1999. 

The uranium bioassay is not expected to fulfill the criteria currently used by NIOSH to evaluate 

coworker data sets. The available bioassay data sheets do not typically indicate work location and 

job title of the worker. Unless NOCTS claimant data was used to develop a model, it would not be 

possible to stratify the available data set or even separate the data out between the two NUMEC 

sites. The NOCTS claimant population is not large. As of June 2016, there are 239 claims for Apollo 

and 97 claims for Parks; 49 of those have co-employment for both sites, the majority of those 

workers having the same job title at both sites. It is not believed that the amount of data available in 

the NOCTS claim files is sufficient for the development of a coworker model as described in OTIB0075. For the workers that had employment listed at both sites, it is generally difficult to place 

him/her at a specific site with the available information. The latter issue affects about 20 % of the 

Apollo claims and about 50 % of the Parks claims. The nature of the work at the NUMEC facilities 
Page 15 of 19

This working document was prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or ABRWH 

(or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary positions 

taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any information 

that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

involved a number of different operations, so there is very little consistency in the exposure profile 

and a rather varied exposure potential, depending on the nature of the work. 

Feasibility of External Coworker Model: 

Many workers at the NUMEC facilities faced radioactive exposure potential; however, it has become 

quite clear from a review of the available files and claimant data that not everyone who worked in 

areas with potential exposure was monitored. An external coworker model, therefore, would be 

useful to assign doses to unmonitored workers. There are a number of occasions where significant 

dose rates in unrestricted areas were observed (AEC, 1967). An external dosimetry spreadsheet was 

developed in 2007, with about 28000 lines of data – see Table 1 for a summary of that data. There 

are several years missing in Table 2 and it is unclear without further research if this data is available. 

Based on the review of claimant records, some external data is available starting in 1957 at Apollo 

and 1959 at Parks. Not all workers were assigned radiation dosimeters and the site relied to some 

extent on work area monitoring for external dose limit enforcement (AEC, 1967). This is also evident 

from some of the claimant records, as there are a number of workers who have internal data but are 

lacking external data. For some years TLD data for certain job titles or work areas are available on 

handwritten log forms (such as ZPPR for 1968 and 1967) (NUMEC, 1968; NUMEC 1969), but for 

other years there are dosimetry reports without indication of work area or job title. There also 

seems to be at times a duality in external dose reporting for some workers, who wore in-house 

NUMEC badges but also had dosimetry records from the commercial vendor. Yet others who clearly 

worked in areas with an exposure potential (as evidenced by available internal monitoring data) 

were not monitored for external exposure. The main reasons for the infeasibility conclusion are the 

available gaps and the inability to separate out the data by site and work area/job title. In some 

cases, the external dosimetry reports from the contractor (such as Landauer) list the facility, but that 

is not always the case. It seems that this practice was taken up sometime in the 70s, but then 

stopped again. It is, therefore, not possible to separate out the data by site. There is also the factor 

that many workers who may have been routinely in radiation areas were not monitored by external 

dosimetry; therefore, the available data may not be representative of all exposure scenarios.

Table 1. Number of external dosimetry results per year

Year Beta Gamma Neutron Shallow Deep Ring Wrist

Total # 

Individuals 

1960 15 15

1964 29 1902 415 35 357 164
Page 16 of 19

This working document was prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or ABRWH 

(or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary positions 

taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any information 

that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Year Beta Gamma Neutron Shallow Deep Ring Wrist

Total # 

Individuals 

1965 19 118 3 34 34 131

1967 39 25 41

1968 6 1200 22 4 921 22 245

1969 239 1693 224 184 197 570

1970 40 983 545 487 295

1971 9 248 566 515 1672 260 197

1972 1 1 1374 674 1128 299 287 332

1973 3 117 593 413 596 70 67 259

1974 1 1 824 815 880 2 1 207

1975 106 927 830 1503 101 356

1976 9 51 31 54

1977 1 1 90 59 94 390 22 95

1978 1 1 281 261 281 232 203 102

1979 1212 423 1211 1354 334 277

1980 505 505 679 128

1981 310 94 310 446 75 91

1982 14 9 285 67 319 326 16 86

1983 1 84 95 126 8 7 55

1984 168 303 303 31 30 110

1985 2 2 26 305 305 29 28 77

1986 94 97 97 1 24

1987 1 1 1 1 1

1988 35 221 222 38

1989 42 164 164 48

1990 24 172 172 25

1991 55 388 388 108

1992 27 92 92 23

1993 11 171 170 43

1994 158 192 93

1995 178 222 82

1996 697 746 13 13 191

1997 497 542 184

1998 596 606 159

1999 120 120 44
Page 17 of 19

This working document was prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or ABRWH 

(or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary positions 

taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any information 

that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Year Beta Gamma Neutron Shallow Deep Ring Wrist

Total # 

Individuals 

2000 87 87 41

Grand 

Total 366 6421 8749 8497 14760 4898 1117

Internal and external coworker model feasibility conclusion: 

NIOSH has concluded that the available internal and external monitoring data available for the NUMEC 

Apollo and Parks facilities has several limitations and it is not expected that a coworker model for nonpresumptive claims would fulfill the criteria that are currently expected of such a model. 

References:

AEC (U.S. Atomic Energy Commission), 1955, “Intercomparison of Film Badge Interpretations,” Isotopics, 

volume 5, number 2, pp. 8–33, SRDB Ref ID: 3640

AEC 1967. Letter from L.D. Low (AEC) to Dr. Zalman Shapiro (President of NUMEC), U.S. Atomic 

Energy Commission. September 5, 1967, SRDB Ref ID: 27213

Boyd, C. C. Jr., 2006c, “BWXT Records Request,” letter with attachments (collection of external 

dosimetry records 1973, internal dosimetry records 1974, 1977, 1978, occupational exposure histories 

1982, 1983, 1985, incident exposure reports 1975) to S. L. Hinnefeld (NIOSH Taft Laboratories), BWXT 

Services, Lynchburg, Virginia, October 25, SRDB Ref ID: 27063.

Brake, R. 1989, untitled letter to G. Runkle (US Department of Energy), Los Alamos National Laboratory, 

Los Alamos, New Mexico, November 9, SRDB Ref ID: 11091

Caldwell, R. D., and W. C. Judd, 1966, Gamma Spectrum Measurements and the Interpretation

of Absorbed Dose During Plutonium Fuel Fabrication, Nuclear Materials and Equipment

Corporation, Apollo, Pennsylvania; SRDB Ref ID: 22776

Caldwell, R.D., 1969. Letter from Roger D. Caldwell (NUMEC) to Lawrence D. Low (AEC) reporting 

overexposures in the plutonium facility. November 4, 1969, SRDB Ref ID: 19970

Crosby, E., 1967, Individual Dosimetry Data PU Facility, SRDB Ref ID: 19734
Page 18 of 19

This working document was prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or ABRWH 

(or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary positions 

taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any information 

that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Davis, A.J., and D.J. Strom, 2008, Uncertainty and Variability in Historical Time-Weighted Average 

Exposure Data, Health Physics, Volume 94, Number 2, pp. 145–160. February 2008

Neton, J. W., 2015, Draft Criteria for the Evaluation and Use of Coworker Datasets, Rev. 4, National 

Institute for Occupational Safety and Health, Division of Compensation Analysis and Support

NIOSH Responses to SC&A Review of ORAUT-TKBS-0041, Rev. 02: Site Profile for Nuclear Materials and 

Equipment Corporation, Apollo and Parks Township, Pennsylvania; Response Paper Rev. 0-A, May 14, 

2015

NUMEC 1967, Individual Dosimetry Data 1967, SRDB Ref ID: 19733

NUMEC, 1968, External Radiation Exposures of Personnel Wearing Film Badges, SRDB Ref ID: 18160

NUMEC, 1969, Annual Personnel Exposure Summary Report, NUMEC Apollo, 7/25/1969, SRDB Ref 

ID: 18159

ORAUT, 2015, Fission and Activation Product Assignment for Internal Dose-Related Gross Beta and Gross 

Gamma Analyses, ORAUT-0054 Rev. 04, 08/27/2015

ORAUT, 2004, Technical Basis Document for the Fernald Environmental Management Project (FEMP) – 

Occupational Internal Dose, ORAUT-TKBS-0015-5, Rev.00, 05/28/2004

ORAUT, 2016, Site Profile for Nuclear Materials and Equipment Corporation, Apollo and Parks Township, 

Pennsylvania, ORAUT-TKBS-0041, Rev 03-B, DRAFT, 06/01/2016

Review of the NIOSH Site Profile for Nuclear Materials and Equipment Corporation Parks Township and 

Apollo Sites. SCA-TR-SP2013_0038, April 2013

SEC Petition Evaluation Report, SEC-00108, Nuclear Materials and Equipment Corporation (NUMEC), 

Parks Township, 3/14/2008

SEC Petition Evaluation Report, SEC-00080, NUMEC Apollo, 8/31/2007

SC&A Assessment of Selected NIOSH Responses to SC&A NUMEC Site Profile Findings, Revision 0, August 

2015

Site Profile for Nuclear Materials and Equipment Corporation, Apollo and Parks Township, Pennsylvania, 

ORAUT-TKBS-0041, Rev 02, 11/26/2012
Page 19 of 19

This working document was prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or ABRWH 

(or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary positions 

taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any information 

that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Williams, R., 1967. Letter from Robert Williams (NUMEC) to James P O'Reilly (NRC Deputy Director) 

documenting the radioactive effluents discharged to unrestricted areas for compliance purposes. 

February 27, 1967, SRDB Ref ID: 20081

Wilson, R.H., J. J. Fix, W. V. Baumgartner, and L. L. Nichols, 1990, Description and Evaluation of the 

Hanford Personnel Dosimeter Program From 1944 Through 1989, PNL-7447, Pacific Northwest 

Laboratory, September, SRDB Ref ID: 4793