Draft Report 

For the Weldon Spring Site Work Group 

SC&A’S EVALUATION OF NIOSH’S JULY 1, 2011, RESPONSE 

CONCERNING RECYCLED URANIUM (SEC ISSUE #5) 

AT WELDON SPRING

Prepared by 

Ron Buchanan 

S. Cohen & Associates 

1608 Spring Hill Road, Suite 400 

Vienna, Virginia 22182 

Saliant, Inc. 

5579 Catholic Church Road 

Jefferson, Maryland 21755

August 2011 

Disclaimer 

This document is made available in accordance with the unanimous desire of the Advisory Board on 

Radiation and Worker Health (ABRWH) to maintain all possible openness in its deliberations. However, 

the ABRWH and its contractor, SC&A, caution the reader that at the time of its release, this report is predecisional and has not been reviewed by the Board for factual accuracy or applicability within the 

requirements of 42 CFR 82. This implies that once reviewed by the ABRWH, the Board’s position may 

differ from the report’s conclusions. Thus, the reader should be cautioned that this report is for 

information only and that premature interpretations regarding its conclusions are unwarranted.
Effective Date: 

August 3, 2011 

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0 Draft) 

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Document No.: SC&A Evaluation 

of NIOSH SEC Issue #5 Response 

Effective Date: 

 Draft – August 3, 2011 

S. COHEN & ASSOCIATES: 

Technical Support for the Advisory Board on 

Radiation & Worker Health Review of 

NIOSH Dose Reconstruction Program Revision No. 

0 (Draft) 

SC&A’S Evaluation of NIOSH’S July 1, 2011, 

Response Concerning Recycled Uranium 

(SEC Issue #5) at Weldon Spring

Page 2 of 9 

Task Manager: 

____________________________ Date:____________ 

Joseph Fitzgerald 

Supersedes: 

N/A 

Project Manager: 

____________________________ Date:____________ 

John Mauro, PhD, CHP 

Peer Reviewer(s): 

 Joseph Fitzgerald 

 

Record of Revisions 

Revision 

Number 

Effective 

Date Description of Revision 

0 (Draft) 08/03/2011 Initial issue 
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NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82.

TABLE OF CONTENTS 

1. Introduction......................................................................................................................... 4 

2. SC&A’s RU SEC Issue....................................................................................................... 4 

3. SC&A’s Summary of NIOSH’s July 1, 2011, Response.................................................... 5 

4. SC&A’s Evaluation of NIOSH’s July 1, 2011, Response .................................................. 6 

5. References........................................................................................................................... 8 
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1. INTRODUCTION 

NIOSH’s Response of 7/01/2011 

NIOSH provided a response to the Weldon Spring Site (WSS) SEC Issue #5 (SC&A 2010) and 

site profile Issue #4 (SC&A 2009) in an e-mail of July 1, 2011, by Mark Rolfes (NIOSH 2011) 

that contained an attachment titled, NIOSH response on WSP Recycled Uranium issues 06-07-

2011.docx. 

Below is a summary of the original recycled uranium (RU) issue; NIOSH’s response of July 1, 

2011; and SC&A’s evaluation of NIOSH’s response. 

2. SC&A’S RU SEC ISSUE 

The following is a breakdown of SC&A’s original RU issue: 

A. RU received in 1961 – SC&A found that the year the dose reconstructor is to start 

assigning all RU doses from the uranium analysis is not consistent within the different Technical 

Base Documents (TBD) and the SEC Evaluation Report (ER). If materials potentially containing 

RU started to be processed in 1961 at the WSS, then the dates should be consistently stated as 

“prior to 1961” and “1961 and after,” not “after 1961” or “after 1962.” Additionally, it has not 

been verified that the WSS did not receive RU before 1961.

B. Application of 100 ppb Pu/U – SC&A found that ORAUT-TKBS-0028-5 (ORAUT 

2005), page 15, recommends that 100 ppb Pu-239, 3,500 ppb Np-237, and 9,000 ppb Tc-99 be 

added to the intake, based on the uranium intake value. SC&A deciphered the contents of 

Fernald ORAUT-TKBS-0017-5 (ORAUT 2005), Table 5-11, conversion factors as follows: 

#pCi Pu-239 = (100 ppb-Pu/U) × (62.89 pCi-Pu/gm-U per 1 ppb-Pu/U) × (#gm-U in bioassay) 

Where: 1 ppb-Pu/U = (1E-9 gm-Pu/gm-U) × (6.21E-2 Ci-Pu/gm-Pu) × (1E12 pCi/Ci) 

~ 62.89 pCi-Pu/gm-U (6.21E-2 Ci-Pu/gm-Pu is the specific activity of Pu-239). 

This is not made very clear in ORAUT-TKBS-0028-5 (ORAUT 2005), page 15, or ORAUTTKBS-0017-5 (ORAUT 2004), page 17, but is applicable if used correctly. The same analysis 

applies to Np-257 and Tc-99. 

However, SC&A’s review of WSS claims indicates that this method was correctly applied in 

only one of the full dose reconstruction (DR) best-estimate cases that SC&A analyzed. While in 

several of the DR cases where the probability of causation was <50% and a full DR should have 

been performed and the EE worked during the 1961–1966 time period, no internal intakes from 

RU were assigned. This is technically a DR issue and not an SEC issue, but the oversight during 

DR may have resulted from the lack of clarity in ORAUT-TKBS-0028-5 (ORAUT 2005). 

 
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C. Differences in TBD and ER and adequacy of 100 ppb Pu/U – Table 5-6, page 27, of 

the NIOSH ER (NIOSH 2010) lists values not found elsewhere in the documents quoted above; 

hence, there does not appear to be consistency between the ER and the TBDs. It is not obvious 

how the values listed in Table 5-6 of the ER were derived from DOE 2000, why they are lower 

than the recommended values found in the WSS TBD, and how they are to be applied in the DR 

process. The reference provided in the ER was DOE 2000, page 1,140; however, there is no 

indication in the ER how the data in Table 1 on page 1,140 and the following pages, generated 

the values listed in Table 5-6 of the ER. SC&A found that a 1964 WSS document (MCW 1964) 

provided some qualitative analyses of alpha and gamma activities and energy spectra, and 

comparative external exposure rates of two feed materials sampled in 1964. However, this does 

not provide quantitative values of Pu-239, Np-237, and Tc-99 by which to derive ppb-U values 

to compare to the Fernald values, or the values recommended in the ER. 

D. Reliability of Documents – Even if the greater concentration values of 100 ppb Pu-239, 

3,500 ppb Np-237, and 9,000 ppb Tc-99 are used, it has not been documented that these values 

are necessarily correct or bounding. SC&A reviewed the source of these concentration values, 

which is a document entitled, DOE Ohio Field Office Recycled Uranium Project Report (DOE 

2000), as referenced in the ER. However, this document does not provide defined sources for its 

recommended values of the radionuclide concentrations; therefore, these concentration values 

appear to be estimates or assumptions, rather than measured values. Because both the WSS TBD 

and the ER base the RU composition and throughput at the WSS on Fernald RU data, then the 

Fernald issues are relevant to the WSS issues and, as SC&A has pointed out in their review of 

the Fernald SEC (SC&A 2007), there are contradictions within the Fernald TBDs, the DOE 2000 

document, and the DOE 2003 document; hence, “it is likely that the DOE 2000, which is the 

basis for the data on RU, is incorrect even for the basic value relating to uranium receipts at 

Fernald” (SC&A 2007, page 35). 

3. SC&A’S SUMMARY OF NIOSH’S JULY 1, 2011, RESPONSE 

NIOSH provides a brief history of the RU contaminates at Atomic Energy Commission (AEC)/ 

Energy Research and Development Administration (ERDA)/Department of Energy (DOE) 

facilities from 1944–2000. One of the important dates is listed in the table on page 4 as 2/15/61

when the first RU was introduced in the process at Fernald (SC&A verified this information in 

DOE 2000 and noted that the correct reference for 1961 on page 4 of NIOSH’s report (NIOSH 

2011) should be 4, not 5. Therefore, according to this document, the WSS could not have 

received RU before February 15, 1961, from Fernald. 

NIOSH explains that the original value of 100 ppb Pu/U was the dose reconstruction default 

value selected for Fernald and represented the highest value listed in Appendix F-1, Table F.3-1, 

page 1,099, of DOE 2000 (with the exception of the tower ash and decontamination residue), 

which did not represent a long-term exposure pathway). Later analyses of the WSS RU issue for 

the ER indicated that Subgroup (SG) 6A was more representative of the WSS operations; 

therefore, the values associated with SG-6A were recommended in the ER. NIOSH states that 

the 1970s and 1980s value of 400 ppb Pu/U at Fernald would not be applicable to the WSS 

operations. 

 
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Health for factual accuracy or applicability within the requirements of 42 CFR 82.

NIOSH goes on to provide some details concerning the industry limits and guides instituted at 

AEC/ERDA/DOE facilities over time, which was generally <10 ppb Pu/U, especially during the 

WSS operational period. NIOSH provides Table 2 on page 7 of NIOSH 2011 that summarized 

the SG-6A and ORAUT-TKBS-0028-5 concentration values for Pu, Np, and Tc. 

In conclusion, NIOSH recommends that the original 100 ppb Pu/U, 3,500 ppb Np/U, and 9,000 

ppb Tc/U be retained, because these values have already been used in previous DR cases, and 

these default values will assure that no worker exposure will be underestimated. 

4. SC&A’S EVALUATION OF NIOSH’S JULY 1, 2011, RESPONSE 

SC&A evaluated NIOSH’s response in view of the four major items contained in the original 

SEC Issue #5, as outlined above in Section 2. 

A. RU received in 1961 – SC&A recommends that TBDs, workbooks, etc., be revised to be 

consistent in the wording concerning when to apply RU intakes at the WSS; i.e., “1961 and 

after.” The documentation SC&A has reviewed to date indicates that this was the earliest date 

RU could have been introduced in the process stream at the WSS on a dosimetric-significant 

basis. 

 

B. Application of 100 ppb Pu/U – SC&A provided a list of five WSS DR cases to NIOSH 

on February 2, 2011, only one of which appeared to have the correct application of 100 ppb 

Pu/U. It is recommended that NIOSH provide an analysis of these five cases, and other WSS 

cases as appropriate, to determine if the 100 ppb Pu/U and Np and Tc concentrations are being 

correctly applied in DR cases. 

C. Differences in TBD and ER and adequacy of 100 ppb Pu/U – SC&A analyzed 

NIOSH’s Fernald and WSS TBDs, the WSS ER recommendations, and the white paper 

exchanges between SC&A and NIOSH concerning concentrations of plutonium, neptunium, and 

technetium in RU. SC&A found that, similar to the Fernald site, the recommended values of 

100 ppb Pu/U, 3,500 ppb Np/U, and 9,000 ppb Tc/U do not provide for adequate bounding of 

potential RU contaminant intakes at the WSS. The recent Fernald values should also be applied 

to WSS because this issue is not site-specific; rather, it depends on the refining and production 

processes. Because the WSS and Fernald used the same refining and production processes, the 

higher values proposed in NIOSH’s response to SC&A’s second white paper on RU at Fernald 

also apply to the WSS. Those values are: 

400 ppb for Pu (Subgroup 8; enriched MgF2) 

 11 ppm Np-237 (Subgroup 11; Waste residues) 

 20 ppm Tc-99 [Subgroup 6B; U03, UF4, and Residues/Intermediates from A508 U03 

 (Low Cross-Over Potential)] 

NIOSH’s makes the statement on page 6 (NIOSH 2011) that: 

This raises the recommended Fernald defaults to 400 ppb plutonium at Fernald. 

These defaults have no direct application to Weldon Spring, since the values 
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listed are derived primarily from higher levels of the 1970s and 1980s and are 

outside the operational time period of Weldon Spring production operations. 

However, this statement is incorrect. The 400 ppb Pu/U is based on the upper 95th percentile of a 

log-normal fit to the enriched MgF2 process subgroup data in DOE 2000 and is representative of 

metals production operations. As discussed extensively in SC&A’s second white paper on RU 

(SC&A 2011) and in our presentation to the Advisory Board at the meeting in St. Louis, 

Missouri, on May 24, 2011, MgF2 was known to concentrate transuranics and fission products, 

and was reused in crucible and reduction vessel liners. Metal production workers were exposed 

to the highest dust loads and highest RU contaminant concentrations at WSS and at Fernald, 

except for the down-blending operators at the latter site. It is critically important to note that 

down-blending at Fernald took place upstream of all subsequent processing steps. Thus, the 

concentration of RU contaminants in MgF2 for metals production was not proportional to the 

levels in feedstocks, and therefore is not correlated with the receipts of highly contaminated 

tower and furnace ashes from the gaseous diffusion plants (GDPs) in the 1970s and 1980s. Thus, 

because the WSS produced uranium metal from RU feedstock in a process nearly identical to 

that at Fernald, the higher contaminant values (particularly 400 ppb for Pu) apply regardless of 

the timeframe. 

D. Reliability of Documents – DOE 2003 did provide some clarification and addressed 

inconsistencies in DOE 2000 and related RU reports. According to DOE 2003, page 8: 

Nine reports were prepared in 2000 that encompassed the years 1952 to 1999 for 

the principal DOE sites that either processed, shipped, or received recycled 

uranium. ... The reports that were published in 2000 contained some 

inconsistencies between quantities of recycled uranium shipped and the quantities 

received. These inconsistencies were caused by differing site accounting 

methods, as well as by the operational definitions of recycled uranium used by the 

sites to determine the quantities of recycled uranium shipped and received. 

However, SC&A believes that if the DOE 2000 and/or DOE 2003 documents are to be used as 

the basis for bounding values for DR purposes, there must be an accounting of the high 

variability in the available data and the associated uncertainties. SC&A has provided an analysis 

of these documents as to their applicability to DR in a recent white paper; further details can be 

found in that review, especially pages 38–44 (SC&A 2011). A summary quote (page 41) and 

Finding #4 (page 43) from that SC&A review are as follows: 

Page 41

Nonetheless, despite the extraordinary accomplishment of preparing [DOE 2000] under 

such challenging circumstances, it cannot serve as a reliable source of information for 

precise or accurate data on TRU and fission product contaminant concentrations 

in recycled uranium that is reliably representative of the RU shipments to 

Fernald, Weldon Spring and other sites. It may or may not be possible to compile 

more complete and representative data, but the analysts who compiled [DOE 

2000] knew at the time that to obtain and analyze the full range of data needed to 
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ensure a reasonably complete and representative characterization of the 

contaminant concentrations would require more time than was available in late 

1999–early 2000. 

Page 43

Finding #4: [DOE 2000] is questionable as the basis for the NIOSH defaults; 

source data should be reviewed in the context of dose reconstruction and an SEC. 

The [DOE 2000] report for RU data is neither comprehensive nor reliably 

representative and rigorous in its scrutiny of data validity. Clearly the subgroups 

listed in Tables ES-5A, 5C and 5D are not sufficiently detailed to reflect the wide 

range of RU sources that would result from analysis of the permutations of 

processing facility, process operations, time of operation and fuel/target type. It 

is incumbent on NIOSH to review the source data for its adequacy in bounding 

worker doses in an SEC context.

It is noteworthy that NIOSH’s response to SC&A 2011 acknowledges the limitations of these 

documents and proposes to use the upper 95th percentiles of lognormal fits to the datasets to 

account for variability and uncertainty. 

5. REFERENCES 

DOE 2000. DOE Ohio Field Office Recycled Uranium Project Report, Final; Department of 

Energy (DOE); May 15, 2000; SRDB Ref ID: 3644. 

DOE 2003. Recycled Uranium: United States Production Enrichment and Utilization, 

Department of Energy (DOE); DOE/SO-0003, May 2003; SRDB Ref ID: 23595. 

ORAUT 2004. Technical Basis Document for the Fernald Environmental Management Project 

– Occupational Internal Dose, ORAUT-TKBS-0017-5, Rev. 00, Oak Ridge Associated 

Universities Team, Cincinnati, Ohio. May 28, 2004. 

ORAUT 2005. Weldon Spring Plant – Occupational Internal Dose, ORAUT-TKBS-0028-5, 

Janet A. Johnson and Roger B. Falk, Rev. 00. Oak Ridge Associated Universities Team, 

Cincinnati, Ohio. June 28, 2005. 

MCW (Mallinckrodt Chemical Works) 1964. Health Physics Consideration for Recycled 

Materials. November 5, 1964. Ref ID: 11818, pdf pages 3–6. 

NIOSH 2010. SEC Petition Evaluation Report, Petition SEC-00143, Rev. 0. National Institute 

for Occupational Safety and Health, Office of Compensation Analysis and Support, Cincinnati, 

Ohio. April 16, 2010. 

NIOSH 2011. NIOSH Responses to Weldon Spring Plant Review – may contain Privacy Act 

information, 7/01/2011 e-mail from Mark Rolfes, with one attachment. National Institute for 
Effective Date: 

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However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82.

NOTICE:

Occupational Safety and Health, Office of Compensation Analysis and Support, Cincinnati, 

Ohio. 

SC&A 2007. Review of the Feed Materials Production Center (FMPC) Special Exposure 

Cohort (SEC) Petition-00046 and the NIOSH SEC Petition Evaluation Report, Rev. 0. SCA-TRTASK5-0056, SC&A, Inc., Vienna, Virginia, and Saliant, Inc., Jefferson, Maryland. May 31, 

2007. 

SC&A 2009. Review of the NIOSH Site Profile for the Weldon Spring Site in Weldon Spring, 

Missouri, Revision 0. SCA-TR-TASK1-0028, February 10, 2009. 

SC&A 2010. Preliminary Issues from SC&A’s Review of NIOSH’s Evaluation Report for the 

Weldon Spring Site, Weldon Spring, Missouri, Special Exposure Cohort Petition SEC-00143. 

SCA-TR-TASK5-0015, October, 2010. 

SC&A 2011. SC&A Review of Issues Related to Reconstruction of Doses for Workers Exposed 

to Recycled Uranium at Fernald – A Second White Paper. Rev. 1-Draft, April 13, 2011.