Draft

Advisory Board on Radiation and Worker Health

National Institute for Occupational Safety and Health

Review of 2019–2020 Revisions to Rocky Flats Plant 

Technical Basis Documents 

Contract No. 75D30119C04183

Document No. SCA-TR-2021-SP001, Revision 0

Prepared by

Joe Fitzgerald, MS, MPH

Ron Buchanan, PhD, CHP

SC&A, Inc.

2200 Wilson Blvd., Suite 300

Arlington, VA 22201-3324

December 3, 2021

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 Review of 2019–2020 Revisions to Rocky Flats Plant Technical Basis 

Documents

Document number SCA-TR-2021-SP001

Revision number 0 (Draft)

Supersedes NA

Effective date December 3, 2021

Task manager Joseph Fitzgerald, MS, MPH [signature on file]

Project manager Bob Barton, CHP [signature on file]

Document reviewer(s) Bob Barton, CHP [signature on file]

Record of revisions

Revision number Effective date Description of revision

0 (Draft) 12/3/2021 Initial issue
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Table of Contents

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

1 Executive Summary.................................................................................................. 6

2 Introduction and Background.................................................................................... 8

3 Review of TBD-2 Site Description, ORAUT-TKBS-0011-2, Rev. 02......................... 8

3.1 Previously identified issues ................................................................................ 8

3.2 Summary and conclusions for TBD-2............................................................... 12

4 Review of TBD-3 Occupational Medical Dose, ORAUT-TKBS-0011-3, Rev. 03 .... 12

4.1 Previously identified issues .............................................................................. 12

4.2 General review of ORAUT-TKBS-0011-3, revision 03 ..................................... 17

4.3 Summary and conclusions for TBD-3............................................................... 18

5 Review of TBD-4 Occupational Environmental Dose, ORAUT-TKBS-0011-4, 

Rev. 03.......................................................................................................................... 18

5.1 Finding 9 – inadequacies in addressing potential environmental exposures.... 18

5.2 Consideration of the FBI investigation on environmental dose reconstruction . 24

5.3 Summary and conclusions for TBD-4............................................................... 25

6 Review of TBD-5 Occupational Internal Dose, ORAUT-TKBS-0011-5, Rev. 04..... 26

6.1 Suggested use of urine bioassay MDA values appear low .............................. 27

6.2 TBD lacks definitive direction in some instances.............................................. 28

6.3 TBD does not consider potential contribution of ingestion pathway ................. 33

6.4 Available proposed wound dose model may be more claimant favorable........ 33

6.5 Critical Mass Laboratory intakes concerning dose reconstruction.................... 33

6.6 Evaluation of the potential for internal dose from neptunium-237 .................... 35

6.7 Reported presence of magnesium-thorium alloy.............................................. 36

6.8 Tritium issues................................................................................................... 37

6.9 Summary and conclusions for TBD-5............................................................... 39

7 Review of TBD-6 Occupational External Dose, ORAUT-TKBS-0011-6, Rev. 03.... 40

7.1 Previously identified issues .............................................................................. 40

7.2 Resolution of findings....................................................................................... 46

7.3 General review of ORAUT-TKBS-0011-6, revision 03 ..................................... 47

7.4 Summary and conclusions for TBD-6............................................................... 51

8 Overall Conclusions ................................................................................................ 51

9 References ............................................................................................................. 54
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Abbreviations and Acronyms

ABRWH, Board Advisory Board on Radiation and Worker Health 

Am americium

AMAD activity median aerodynamic diameter

Bq becquerel

CDPHE Colorado Department of Public Health and Environment 

CEDR Comprehensive Epidemiologic Data Resource 

CFR Code of Federal Regulations 

Ci curie

CML Critical Mass Laboratory

Co cobalt

Cs cesium

D&D decontamination and decommissioning 

DOE U.S. Department of Energy

DR dose reconstruction 

DU depleted uranium 

EEOICPA Energy Employees Occupational Illness Compensation Program Act 

FBI Federal Bureau of Investigation 

ICRP International Commission on Radiological Protection 

INEEL Idaho National Environmental and Engineering Laboratory 

IREP Interactive RadioEpidemiological Program 

keV kiloelectron volt 

LANL Los Alamos National Laboratory 

LOD limit of detection

m meter

m3 cubic meter

MDA minimum detectable activity

MeV mega-electron volt 

MFAP mixed fission and activation product 

Mg-Th magnesium-thorium 

MOD Transportation Modification 

mrem millirem
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NCRP National Council on Radiation Protection and Measurements 

NDRP neutron dose reconstruction project 

NIOSH National Institute for Occupational Safety and Health

Np neptunium 

NTA nuclear track emulsion, type A (film) 

NUREG Nuclear Regulatory Report (U.S. Nuclear Regulatory Commission) 

OCAS Office of Compensation Analysis and Support 

ORAU Oak Ridge Associated Universities

ORAUT Oak Ridge Associated Universities Team

ORNL Oak Ridge National Laboratory 

pCi/m3 picocurie per cubic meter

PFG photofluorography 

ppm parts per million

Pu plutonium 

R&D research and development

RATCHET Regional Atmospheric Transport Code for Hanford Environmental Tracking 

RFETS Rocky Flats Environmental Technology Site 

RFP Rocky Flats Plant 

SEC Special Exposure Cohort 

SRDB Site Research Database

TBD technical basis document

Th thorium 

TLD thermoluminescent dosimeter

TLLα total long-lived alpha 

TRU transuranic 

U uranium 

UNH uranyl nitrate 

yr year
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1 Executive Summary

SC&A reviewed all five Rocky Flats Plant (RFP) technical basis documents (TBDs) that have 

been revised as of January 2021 to determine if previous issues identified by its original 2005 

site profile review (SC&A, 2005), as well as by the work group in its proceedings, were resolved 

and addressed by SC&A and the National Institute for Occupational Safety and Health (NIOSH).

SC&A also performed a general review of the five revised TBDs:

• Site description (TBD-2): ORAUT-TKBS-0011-2, revision 02, “Rocky Flats Plant – Site 

Description” (NIOSH, 2020a)

• Occupational medical dose (TBD-3): ORAUT-TKBS-0011-3, revision 03, “Rocky Flats 

Plant – Occupational Medical Dose” (NIOSH, 2019a)

• Occupational environmental dose (TBD-4): ORAUT-TKBS-0011-4, revision 03, “Rocky 

Flats Plant – Occupational Environmental Dose” (NIOSH, 2020b)

• Occupational internal dose (TBD-5): ORAUT-TKBS-0011-5, revision 04, “Rocky Flats 

Plant – Occupational Internal Dose” (NIOSH, 2020c)

• Occupational external dose (TBD-6): ORAUT-TKBS-0011-6, revision 03, “Rocky Flats 

Plant – Occupational External Dose” (NIOSH, 2019b)

SC&A found that for TBD-2, the site description, all previous issues have been addressed in 

revision 02 (NIOSH, 2020a). A general review found revision 02 to be more comprehensive in 

scope and depth and to include more details on site closure and decommissioning, as well as 

specific information about operations involving recycled uranium and uranium (U)-233. SC&A 

recommends closure of finding 8 (inadequate information regarding recycled uranium) from its 

original review (SC&A, 2005), based on updated treatment of the issue in the internal dose TBD 

(TBD-5). However, no such updated assessment was noted in TBD-2, and SC&A recommends

that TBD-2 be revised to be consistent with TBD-5. SC&A considers all other identified issues 

resolved.

For TBD-3 on occupational medical dose, SC&A similarly found that all previous issues 

expressed in finding 5 (which was concerned with radiation exposure from occupationally 

necessitated medical x-rays) have been addressed and resolved in revision 03 of TBD-3 (NIOSH,

2019a), and recommends closure. A general review of this most recent revision did not identify 

any findings, although some incorrect tables were listed in the “Publication Record” and on 

page 2 of the TBD.

SC&A’s review of TBD-4, revision 03 (NIOSH, 2020b), on occupational environmental dose, 

found that the revised TBD addressed and resolved SC&A’s finding 9 from its original 2005 site 

profile review regarding inadequacies in addressing potential environmental exposure from 

routine and ambient airborne releases and resuspension of contaminated soil at RFP. SC&A 

found that more specific information and guidance has been added about the contribution of 

resuspension of soil contaminants for occupational environmental exposures and that NIOSH 

provides better justification of its basis in available site monitoring data. Therefore, SC&A 

recommends closure of this finding. SC&A finds that the potential impact of the 1989 Federal 
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Bureau of Investigation (FBI) investigation on environmental dose reconstruction (DR) has been 

addressed, resolved, and previously closed. 

For TBD-5, SC&A’s (2005) original site profile review had three findings and one observation; 

later work group proceedings identified additional concerns for internal exposures related to the 

Critical Mass Laboratory (CML), neptunium, magnesium-thorium (Mg-Th), and tritium. For 

these later concerns, the work group, SC&A, and NIOSH addressed and resolved them during 

work group deliberations. SC&A finds that they are adequately reflected in TBD-5, revision 04 

(NIOSH, 2020c), as appendices.

For finding 1 of its 2005 review (“Suggested use of urine bioassay MDA values for plutonium 

and americium appear low”) and finding 2 (“TBD lacks definitive direction in some instances”) 

(SC&A, 2005, p. 15), SC&A now finds that NIOSH has addressed and resolved them in TBD-5, 

revision 04 (NIOSH, 2020c), and recommends closure.

For finding 7 (“The internal TBD does not consider potential contribution of ingestion pathway”; 

SC&A, 2005, p. 17), SC&A continues to find a lack of clarity about how ingestion intakes would 

be handled by dose reconstructors. TBD-5, revision 04 (NIOSH, 2020c), only refers to ORAUTOTIB-0060, revision 02, “Internal Dose Reconstruction” (NIOSH, 2018b), on page 22 in 

reference to selecting solubility type. ORAUT-OTIB-0060 addresses ingestion intakes on 

pages 16 and 38, which refer to OCAS-TIB-009, revision 0, “Estimation of Ingestion Intakes” 

(NIOSH, 2004f). For clarity, SC&A believes that TBD-5 should include recommendations for 

ingestion intakes or direct reference to the appropriate ingestion intake-related document. 

Although SC&A understands that this issue has been resolved in practice, ingestion intakes 

should be addressed by specific guidance in TBD-5 with reference to OCAS-TIB-009. 

Therefore, SC&A recommends that this issue remain open until appropriate revisions are made 

in TBD-5. 

For TBD-6, the external dose TBD, SC&A reviewed revision 03 (NIOSH, 2019b) and compared 

it with the 2005 site profile review (SC&A, 2005). SC&A determined that the issues identified 

the five 2005 findings have been addressed and resolved. Therefore, SC&A recommends closure 

of all findings and issues. The five findings were as follows: 

• Finding 3 was concerned with the interpretation of nuclear track emulsion, type A (NTA) 

film data for workers who were not included in the neutron dose reconstruction project 

(NDRP). The revised TBD-6 addressed this finding. 

• Finding 4 was concerned with the treatment of personal dosimeter placement and angular 

dependence. The revised TBD-6 resolved this finding by analysis of angular dependence 

of the monitoring devices. 

• Finding 6 was concerned with potential calibration errors, technology deficiencies, and 

possible data integrity issues that could have contributed to missed dose. The revised 

TBD-6 addressed and resolved these issues. 

• Finding 10 was concerned with hand and wrist doses. The revised TBD-6 addressed these

extremity doses. 
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• Finding 11 was concerned with the potentially significant doses from industrial x-ray and 

neutron generators for research and development (R&D) and nondestructive work. The 

revised TBD-6 addressed these issues. 

The issue of the Gammacell 220 irradiator and cobalt (Co)-60 orphan source was previously 

discussed, resolved, and closed during the RFP work group meeting of October 28, 2015 

(ABRWH, 2015, pp. 23–31). 

SC&A’s general review of the TBD found no further issues but did result in three observations: 

1. Use of different neutron dose multiplier factors needs clarification. 

2. Limit of detection (LOD) values for 1962 and 1963 need clarification. 

3. References for LOD values for 2004 and 2005 are needed. 

Additionally, several other references need to be added, and the attachment C list of tables on 

page 93 incorrectly substitutes “plutonium” for “uranium” in the table C-8 caption (NIOSH, 

2019b). 

2 Introduction and Background

The Rocky Flats Plant Work Group tasked SC&A with a review of the revised RFP TBDs on 

January 22, 2021, to determine if previous issues were addressed and resolved by the revised 

TBDs. The following sections summarize SC&A’s (1) evaluation of the revised TBDs in view of 

previously identified issues and (2) general review of the documents. 

3 Review of TBD-2 Site Description, ORAUT-TKBS-0011-2, Rev. 02

The following sections summarize SC&A’s evaluation of the revised TBD-2 site description, 

ORAUT-TKBS-0011-2, revision 02 (NIOSH, 2020a), in view of previously identified issues and 

a general review of the document.

3.1 Previously identified issues

In its 2005 original site profile review (SC&A, 2005), SC&A identified several gaps in the site 

description in ORAUT-TKBS-0011-2, revision 00 (NIOSH, 2004a). SC&A reviewed revision 02 

of TBD-2 (NIOSH, 2020a) to determine if those identified gaps and others identified during 

work group reviews had been addressed and resolved. The following documents are relevant to 

this review: 

• ORAUT-TKBS-0011-2, revision 00 (NIOSH, 2004a) 

• SC&A’s December 2005 SCA-TR-TASK1-0008, revision 0, “Rocky Flats Plants Site 

Profile Review” (SC&A, 2005) 

• ORAUT-TKBS-0011-2, revision 02 (NIOSH, 2020a) 
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The issues that need further consideration, as identified in SC&A’s site profile review (SC&A, 

2005), were as follows: 

• Finding 8: “TBDs do not adequately address potential exposure contribution of recycled 

uranium and other radiation sources shipped onsite” (SC&A, 2005, p. 17). Addressed in 

SC&A (2005) section 5.4.1, “Inadequate Information Regarding Recycled Uranium.” 

Also, the TBD “makes only a passing reference to the processing of 233U” (SC&A, 2005, 

p. 17). Addressed in SC&A (2005), section 5.4.3, “Inadequate Information Regarding the 

Processing of Uranium-233.” 

• Observation 1: “The RFP site profile does not address post-production (post-1992) 

decontamination and decommissioning activities and worker exposures” (SC&A, 2005, 

p. 18). Discussed in SC&A (2005), section 5.8.3, “Inadequate Description of PostProduction Mission at Rocky Flats,” section 5.4.2, “Inadequate Information Regarding 

Highly-Enriched Uranium Storage Vulnerabilities,” and section 5.8.4, “Inadequate 

Description of Nuclear Plutonium Storage Activities and the Absence of Related Dose 

Reconstruction Guidance.” 

SC&A (2005) originally presented these issues in both narrative form in the sections given in the 

preceding list and in a specific finding or observation. The following subsections summarize 

SC&A’s evaluation of the status of this finding, observation, and other issues in view of the 

information in TBD-2, revision 02 (NIOSH, 2020a), and documents, procedures, and accepted 

practices that have been developed since SC&A’s review of TBD-2, revision 00, in 2005. 

3.1.1 SC&A (2005) finding 8, section 5.4.1 – inadequate information regarding recycled 

uranium

SC&A’s 2005 review of the RFP site profile led to finding 8: 

The RFP site description TBD (Flack and Meyer 2004) does not provide an 

accurate assessment of the potential risks associated with recycled uranium. 

According to a U.S. Department of Energy report (DOE 2000), the DOE’s Idaho 

National Environmental and Engineering Laboratory (INEEL) shipped quantities 

of 236U recovered from previously irradiated reactor fuel in 1955 to the RFP. This 

represents a potential for significant gamma fields and a potential source of 

missed dose for RFP workers. [SC&A, 2005, p. 17] 

TBD-2, revision 02 (NIOSH, 2020a), makes the following statement, which is nearly identical to 

that in revision 01 (NIOSH, 2007a, p. 11): 

While Paducah was processing recycled uranium beginning in 1953, available 

RFP records do not indicate whether fission product or transuranic (TRU)-

contaminated uranium was processed at RFP. [NIOSH, 2020a, p. 11] 
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However, NIOSH’s 2014 RFP internal dose TBD (TBD-5, revision 03)1 indicated a substantive 

revision to accommodate assessment of potential recycled uranium exposure at Rocky Flats: 

1 Where substantive changes were made in earlier TBD versions, SC&A has chosen to reference those changes in 

terms of resolutions or clarifications achieved for findings and observations.

Revision initiated to incorporate Advisory Board comments, the approval of 

SEC-00192, and new dose reconstruction approaches in assessing tritium, 233U, 

and recycled uranium. [NIOSH, 2014a, p. 2] 

In TBD-5, revision 03, NIOSH provided guidance for DR: 

For all DOE uranium after 1952, this analysis assumed the possibility that 

uranium from refineries was recycled uranium or contained recycled uranium. 

Table 5-5 provides the activity fractions that should be applied to all uranium 

intakes after 1952. [NIOSH, 2014a, p. 18] 

This guidance is consistent with work group discussions on March 27, 2006 (ABRWH, 2006a), 

which acknowledged the likely presence of recycled uranium at RFP (after 1952) and indicated 

that programwide guidelines would be applied for assessment of recycled uranium contributions 

to exposure. 

On the basis of its acknowledgement and treatment in TBD-5, SC&A recommends closure of 

this issue from a substantive standpoint. However, SC&A also recommends that, for consistency, 

TBD-2, revision 02, be revised to reflect this understanding. 

3.1.2 SC&A (2005) section 5.4.3 – inadequate information regarding the processing of 

uranium-233

In its 2005 site profile review, SC&A found that: 

The TBD makes only a passing reference to the processing of 233U. From 1945 to 

the early 1980s, a considerable amount of effort involving several sites in the 

Federal nuclear complex was made by the Atomic Energy Commission and its 

successor agencies to produce 233U and to develop military and civilian 

applications for this fissile material. Between 1965 and the mid 1980s, DOE 

records indicate that the RFP routinely handled kilogram quantities of 233U. 

[SC&A, 2005, p. 68] 

NIOSH acknowledged the need to address U-233 and other radionuclides, such as 

neptunium (Np)-237 and thorium, from a DR feasibility standpoint and addressed them in its 

Special Exposure Cohort (SEC) Petition-00192 evaluation report. NIOSH’s September 30, 2013, 

evaluation report found that: 

Uranium-233 and associated progeny exposure was related to receipt and 

processing of U-233 residues. Processing involved thorium strikes to extract 

Th-228, which was containerized and shipped to Idaho National Laboratory. The 

uranium was then converted to a peroxide and ultimately reduced to U-233 metal. 
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In its review of available bioassay records for individuals identified as having 

worked in U-233 processing areas, NIOSH has determined that uranium bioassay 

data may not be available for all potentially-affected individuals. In additional, 

these same workers were also potentially exposed to Th-228. NIOSH lacks 

thorium bioassay data for Rocky Flats personnel. Furthermore, NIOSH has 

determined that workplace air monitoring and contamination surveys for U-233 

processes are insufficient for dose reconstruction purposes. Without uranium and 

thorium bioassay results, NIOSH has concluded that it cannot estimate with 

sufficient accuracy the potential internal exposures to U-233, U-232, and Th-228 

which the proposed class may have received from 1964 through 1983. [NIOSH, 

2013, p. 5] 

Based on its treatment and inclusion in the SEC evaluation and later acknowledgment in TBD-2, 

revision 02, SC&A recommends closure of this issue.

3.1.3 Inadequate description of post-production mission at Rocky Flats

Observation 1 is based, in part, on information about highly enriched uranium storage 

vulnerabilities (section 5.4.2) and nuclear plutonium storage activities (section 5.8.4). 

In observation 1, SC&A noted: 

The RFP site profile does not address post-production (post-1992) 

decontamination and decommissioning activities and worker exposures. This 

period involved nuclear material storage, nuclear material stabilization and 

packaging, waste management, and decontamination and decommissioning, for 

which records show a history of contamination incidents and personnel exposure. 

[SC&A, 2005, p. 18] 

SC&A further addressed this issue in terms of long-term storage activities involving highly

enriched uranium and plutonium after RFP production activities ceased in 1989: 

Similarly, the environmental, safety, and health vulnerabilities associated with the 

storage of plutonium and high enriched uranium at RFP during these and previous 

time periods are not addressed. For example, in the 1990s, RFP held over metric 

tons of highly enriched uranium (HEU) consisting mostly of metals in the form of 

pits, part samples, and scrap. [SC&A, 2005, p. 18] 

TBD-2, revision 01 (NIOSH, 2007a), included a new section (2.5, “Site Closure and 

Decommissioning”), which is carried over to TBD-2, revision 02 (NIOSH, 2020a). This section

describes the post-production mission of RFP and the timeline and operations involved in 

specific building closure and decommissioning. This includes operations involving stored 

uranium and plutonium. 

Based on the addition of this new section to TBD-2, SC&A recommends closure of this 

observation and related issues. 
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3.2 Summary and conclusions for TBD-2 

SC&A summarized the issues previously presented in SC&A’s (2005) review of TBD-2, 

revision 00 (NIOSH, 2004a), to determine if the issues were addressed in TBD-2, revision 02 

(NIOSH, 2020a). SC&A found that the finding, observation, and issues have been addressed and

resolved and recommends closure. However, to avoid confusion, it is recommended that TBD-2 

be revised to be consistent with TBD-5 on the treatment of recycled uranium. 

SC&A performed a general review of TBD-2, revision 02, and did not identify any findings or 

concerns. The 2020 revised TBD is considerably expanded in detail and scope from the 2004 

first version and includes information about historical facilities, operations, and potential 

exposure sources that were not included in previous versions of TBD-2. 

4 Review of TBD-3 Occupational Medical Dose, ORAUT-TKBS-0011-3, 

Rev. 03

The following sections summarize SC&A’s evaluation of the revised TBD-3 for occupational 

medical dose, ORAUT-TKBS-0011-3, revision 03 (NIOSH, 2019a), in view of previously

identified issues and a general review of the document. 

4.1 Previously identified issues

In its 2005 site profile review (SC&A, 2005), SC&A identified several potential DR issues in 

ORAUT-TKBS-0011-3, revision 00 (NIOSH, 2004b), for RFP energy employees. SC&A 

reviewed revision 03 of TBD-3 (NIOSH, 2019a) to determine if the potential DR issues had been 

addressed and resolved. The following documents are relevant to this review: 

• ORAUT-TKBS-0011-3, revision 00 (NIOSH, 2004b) 

• SCA-TR-TASK1-0008, revision 0 (SC&A, 2005) 

• ORAUT-TKBS-0011-3, revision 03 (NIOSH, 2019a) 

Finding 5 of SC&A’s 2005 report was that “The RFP occupational medical dose TBD does not 

adequately address the contribution of historic radiation exposure from occupationally 

necessitated medical x-ray exposure of workers at Rocky Flats” (p. 16). SC&A (2005) discussed 

the potential DR issues needing further consideration under finding 5 in the following sections 

(pp. 97–101): 

• Section 5.10.1, “Guidelines Needed on What Constitutes Occupational Medical 

Exposure” 

• Section 5.10.2, “Potential for Other Types of X-ray Exposures” 

• Section 5.10.3, “Frequency and Types of X-ray Exposure Is Derived from Other Sites” 

• Section 5.10.4, “The Determination of Machine and Technician Uncertainties” 

• Section 5.10.5, “Use of Screens, Grids, and Impact of Off-site Medical X-rays Are Not 

Considered” 
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SC&A (2005) presented these five issues in a narrative form, unlike the present practice of 

developing a topic and then stating a concluding finding (or observation). Therefore, this report 

summarizes the issues from the SC&A (2005) narrative to present the important points to be 

addressed.

The following subsections summarize SC&A’s evaluation of the status of these five issues in 

view of the information in TBD-3, revision 03 (NIOSH, 2019a), and documents, procedures, and 

accepted practices that have been developed since SC&A’s 2005 review of TBD-3, revision 00. 

4.1.1 SC&A (2005) section 5.10.1 – guidelines needed on what constitutes occupational 

medical exposure

In this section, SC&A had concerns that it is not claimant favorable to limit occupational medical 

examinations to one or two chest x-rays annually, unless medical records and protocols clearly 

limit the use of radiography to a small fraction of workers, which was not the case up to the 

mid-1980s. 

SC&A reviewed the revised TBD-3, revision 03 (NIOSH, 2019a), to determine if this issue was 

addressed and resolved. SC&A found that NIOSH addressed the issue as follows in revision 03: 

• Section 3.2 (p. 8) states: 

Only medical exposures that were required as a condition of employment 

are included; diagnostic and therapeutic procedures that were not required 

for employment are excluded (e.g., exposures that were received in the 

treatment of work-related injuries).

• Table 3-5 (p. 12) summarizes the recommended default x-ray examination frequencies 

for all RFP workers for 1952–2005. 

These recommend x-ray examination frequencies and views are compatible with those 

recommended at the major U.S. Department of Energy (DOE) sites. 

SC&A finds that this issue has been addressed and recommends closure. 

4.1.2 SC&A (2005) section 5.10.2 – potential for other types of x-ray exposures

In this section, SC&A (2005) had concerns that TBD-3, revision 00 (NIOSH, 2004b):

• Did not address the potential use of other forms of diagnostic radiography to support 

medical injury diagnosis. This may involve use of isotopes, sealed sources, etc. 

• Did little to catalog the number, types of x-ray equipment, frequency of use, etc. Little 

information exists about protocols to govern the utilization of x-ray units. 

• Failed to document that available x-ray units were not operated at greater than 80–

90 kilovolt-peak. In light of this, there is a need to reconsider the approach for 

reconstructing medical radiation exposures. 
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SC&A reviewed the revised TBD-3, revision 03 (NIOSH, 2019a), to determine if these items 

were addressed and resolved. SC&A found that these items were addressed as follows in 

revision 03 of TBD-3: 

• Section 3.2 (p. 8) states: 

Only medical exposures that were required as a condition of employment 

are included; diagnostic and therapeutic procedures that were not required 

for employment are excluded (e.g., exposures that were received in the 

treatment of work-related injuries). [Emphasis added.] 

• Section 3.2 (p. 8) recommends the use of ORAUT-OTIB-0006, revision 05, “Dose 

Reconstruction from Occupational Medical X-Ray Procedures” (NIOSH, 2018a), for 

x-ray equipment parameters because the details of the RFP x-ray equipment are not 

complete. The available RFP x-ray equipment information is summarized in table 3-1 and 

table 3-2 (NIOSH, 2019a, p. 8). 

• Section 3.4.2 (p.10) recommends assigning the x-ray dose as 30–250 kiloelectron volt 

(keV) photons. The RFP x-ray units were operated at a maximum of 125 kilovolt-peak 

(Kaiser Hill, 2003).

SC&A finds that these items have been addressed and recommends closure of this issue. 

4.1.3 SC&A (2005) section 5.10.3 – frequency and types of x-ray exposure is derived 

from other sites

In section 5.10.3, SC&A (2005) had concerns that TBD-3, revision 00 (NIOSH, 2004b):

• Relies on assumptions of x-ray frequency derived from other DOE sites. The assumption 

of one to two chest radiographs per year is not reasonably conservative, in that workers 

could essentially request an x-ray. The frequency of screenings and the number and types 

of workers receiving x-rays varied from site to site. 

• Relies on retake rates (3 percent) derived from other DOE sites. A comparison review of 

Federal facilities, such as by the U.S. Department of Defense during the 1970s using lesstrained technicians (Federal regulations did not require technician certification), showed 

that retakes sometimes ran up to 30 percent for abdominal examinations and often over 

15 percent for chest radiography. 

• Does not address the issue that there were photofluorography (PFG) units at RFP for 

20 years, suggesting their potential heavy use, far more than at any other DOE site. 

SC&A reviewed the revised TBD-3, revision 03 (NIOSH, 2019a), and related documents to 

determine if these items were addressed and resolved. SC&A found that these items were 

addressed as follows in revision 03 of TBD-3: 

• Table 3-5 (NIOSH, 2019a, p. 12) summarizes the recommended default x-ray 

examination frequencies for all RFP workers for 1952–2005. 
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These recommended x-ray examination frequencies and views are comparable to those 

recommended at the major DOE sites. 

• The retake rate at RFP has not been documented, but ORAUT-OTIB-0006 (NIOSH, 

2018a, p. 25) states:

In the DOE complex, Los Alamos National Laboratory reported a retake 

rate of 2.2% in 1998 . . .; Lawrence Berkeley National Laboratory reported 

a retake rate of 0% in 1991 . . . ; no retake program was in place at 

Lawrence Livermore National Laboratory in 1991 . . . or at Brookhaven 

National Laboratory in 1994 . . . . These do not support the automatic 

inclusion of retakes as an additional source of exposure to each worker, 

but if dose reconstructors encounter records of retakes in individual claim 

file records, the dose from them should be included. 

• Section 3.3 of TBD-3, revision 03 (NIOSH, 2019a, p. 9), states:

Based on X-ray inventory records provided after February 2009, 

photofluorography (PFG) examinations were performed at RFP. A note in 

the available documentation indicates that the fluoroscope was removed 

from the plant in 1968 [MFG, 2003]. There is not enough information 

about the machine and settings to derive site-specific doses; therefore, 

default PFG doses from [NIOSH, 2018a] are assigned. 

The recommended PFG examinations for 1952–1968 are provided in tables 3-4 and 3-5 

of TBD-3, revision 03 (NIOSH, 2019a).

SC&A finds that these items have been addressed and recommends closure of this issue. 

4.1.4 SC&A (2005) section 5.10.4 – determination of machine and technician 

uncertainties

In this section, SC&A (2005) had concerns that TBD-3, revision 00 (NIOSH, 2004b):

• Provides little documentation to support the assumed techniques and protocols applied to 

calculate the dose.

• Does not address the potential impact of associated uncertainties nor provide 

documentation to warrant its assumption that multiplication of estimated doses by a 

factor of 1.3 is claimant favorable.

SC&A reviewed the revised TBD-3, revision 03 (NIOSH, 2019a), and other x-ray-related 

documents to determine if these items were addressed and resolved and found: 

• TBD-3, revision 03 (NIOSH, 2019a), provides some information concerning lumbar 

views in table 3-4. However, since the details of some of the RFP x-ray parameters are 

not available for most of the RFP operating period, the operating parameters in ORAUTOTIB-0006 (NIOSH, 2018a) are recommended as reasonable default values.
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• ORAUT-OTIB-0006, revision 05 (NIOSH, 2018a, p. 38), states:

However, a more reasonable approach is to assume that the uncertainties 

are in fact random, and therefore to compute the combined statistical 

uncertainty as the square root of the sum of the squares of all the 

uncertainties, which is ±28.9%. Rounding this up to ±30% provides an 

adequate and suitably conservative indication of uncertainty. Therefore, 

for a derived dose equivalent to an individual organ, a total combined 

standard uncertainty of ±30% can be assumed. Dose reconstructors 

should, therefore, input the organ dose equivalent as the mean of a normal 

distribution, with a standard uncertainty of ±30%. 

• The present default value of 30 percent uncertainty is used throughout the DOE complex 

for occupational medical DR. Since some of the details of the RFP x-ray characteristics 

are not available for most of the RFP operating period, 30 percent uncertainty is a 

reasonable default value to use for RFP occupational medical DR. 

SC&A finds that these items have been addressed and recommends closure of this issue. 

4.1.5 SC&A (2005) section 5.10.5 – use of screens, grids, and impact of offsite medical 

x-rays are not considered

In this section, SC&A (2005) had concerns that TBD-3, revision 00 (NIOSH, 2004b):

• Does not consider the dose impact due to less than optimal use of technology, such as 

using screens, grids, or bucky systems. 

• Does not consider offsite medical exposure as part of worker exposure. 

SC&A reviewed the revised TBD-3, revision 03 (NIOSH, 2019a), and related x-ray documents 

to determine if these items were addressed and resolved.

• SC&A finds that since the details of some of the RFP x-ray parameters are not available 

for most of the RFP operating period, the operating parameters in ORAUT-OTIB-0006 

(NIOSH, 2018a) are recommended as reasonable default values. These parameters have 

been applied to other DOE facilities where specific information about the x-ray 

examination parameters is not available.

• Since the 2005 SC&A review, NIOSH has developed ORAUT-OTIB-0079, revision 02, 

“Guidance on Assigning Occupational X-Ray Dose Under EEOICPA for X-Rays 

Administered Off Site” (NIOSH, 2017a). In table 3-2 (p. 11) of ORAUT-OTIB-0079, 

RFP is listed as a DOE site where onsite occupational medical x-rays were performed on 

site for all years of DR. 

SC&A finds that these items have been addressed and recommends closure of this issue. 

SC&A finds that the issues outlined in finding 5 have been sufficiently addressed, resolved, and 

included in the revised TBD-3. SC&A recommends closure of finding 5. 
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4.2 General review of ORAUT-TKBS-0011-3, revision 03

SC&A had not performed a general review of the RFP occupational medical dose TBD since 

2005; therefore, SC&A performed a general review of TBD-3, revision 03 (NIOSH, 2019a), to 

determine its technical accuracy and applicability to the RFP DR process. The following 

summarizes the results of SC&A’s review: 

• Revisions – The RFP occupational medical dose TBD has been revised three times (2007, 

2017, and 2019) since its initial issue in 2004 (NIOSH, 2004b, 2007d, 2017b, 2019a). 

These revisions revised and updated information and dose values in the tables.

• Current revision – TBD-3, revision 03 (NIOSH, 2019a), divides occupational medical 

dose at RFP into two time periods: (1) April 1, 1952–June 10, 2001, and (2) June 11, 

2001–March 31, 2005. TBD-3, revision 03, states (p. 9): 

Section 3.4.1 describes the method used to estimate the doses postJune 11, 2001, when there is enough information to calculate site-specific 

organ doses. As discussed in Section 3.3, not all equipment or settings 

information about what was in use at RFP before 2001 has been located. 

Therefore, site-specific organ doses cannot be calculated for the time 

period prior to June 11, 2001, and default dose values are assigned from 

[NIOSH, 2018a].

• Two time periods – Because of the two time periods defined in the previous item, TBD-3, 

revision 03, refers all pre-June 11, 2001, occupational medical x-ray doses for DR to 

ORAUT-OTIB-0006 (NIOSH, 2018a). For the latter period, June 11, 2001–March 31, 

2005, TBD-3, revision 03, provides the standard occupational medical x-ray dose 

information (e.g., table 3-3 and table A-1). This specific RFP medical x-ray information 

is based on information recorded in a 2003 RFP x-ray machine shielding calculation 

summary (Kaiser Hill, 2003), a 2002 performance summary (Dyn Corp, 2002, PDF p. 5), 

and International Commission on Radiological Protection (ICRP) Publication 34 (ICRP, 

1982). 

SC&A’s review of TBD-3, revision 03, indicated that NIOSH used the information available to 

provide reasonable occupational medical x-ray DR considering the limited information and data 

available, especially for the early years. SC&A reviewed the references used in TBD-3, 

revision 03, to support the conclusions and recommendations and found them to be applicable.

SC&A reviewed the dose values recommended in tables 3-3 and A-1, verified their derivation, 

and found them to be correct. The factor of 1.8 for three-phase x-ray units is accounted for in 

TBD-3, revision 03, page 9. 

SC&A does note that the “Publication Record” on page 2 of revision 03 contains incorrect table 

references for revision 03 (table 3-7 and table A-2 are no longer used in this version). Also, the 

reference to table 3-4 in at the end of the second paragraph in section 3.4.2 (p. 10), should be 

corrected to table 3-3, which has the organ dose estimates. 
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4.3 Summary and conclusions for TBD-3 

SC&A summarized the issues previously presented in a narrative form in SC&A’s (2005) review 

of TBD-3, revision 00 (NIOSH, 2004b), to determine if the issues were addressed in TBD-3, 

revision 03 (NIOSH, 2019a), other x-ray-related documents, or currently accepted practices. 

SC&A found that the issues have been addressed and resolved and recommends closure of the 

five issues identified in finding 5 of SC&A’s 2005 review. 

SC&A performed a general review of TBD-3, revision 03, and did not identify any additional 

issues. SC&A did locate some incorrect tables listed in the Publication Record (p. 2) and on 

page 10 of revision 03. 

5 Review of TBD-4 Occupational Environmental Dose, ORAUT-TKBS0011-4, Rev. 03

SC&A reviewed the revised occupational environmental dose TBD, ORAUT-TKBS-0011-4, 

revision 03 (NIOSH, 2020b), and compared it with TBD-4, revision 01 (NIOSH, 2004e), issued 

June 29, 2004, which SC&A (2005) reviewed and found one finding, one observation, and other 

issues. The following documents are relevant to this review:

• ORAUT-TKBS-0011-4, revision 01 (NIOSH, 2004e) 

• SCA-TR-TASK1-0008, revision 0 (SC&A, 2005) 

• ORAUT-TKBS-0011-4, revision 03 (NIOSH, 2020b) 

In that review, SC&A determined that the environmental dose TBD (NIOSH, 2004e) had several 

deficiencies, including the following (SC&A, 2005, p. 88): 

(1) Need for source term and exposure pathways re-examination

(2) Need for a timeline for phases of operations, and data availability and types 

(3) Data adequacy and completeness

(4) Ambiguous recommendations for particle size 

(5) Uncertainty with the RATCHET model 

These deficiencies were cited in finding 9 and observation 2 of SC&A’s (2005) report.

5.1 Finding 9 – inadequacies in addressing potential environmental exposures

Finding 9 of SC&A’s (2005) site profile review stated: 

The occupational environmental TBD does not adequately address potential 

environmental exposure from ambient airborne releases and resuspension of 

contaminated soil. Routine and episodic ambient airborne releases have been 

brought into question, based on the adequacy of air monitoring results. Incidental 

releases determined by the state of Colorado are higher than the values used for 

the 1957 and 1969 fires in the TBD, resulting in non-claimant-favorable 

assumptions. The dose from resuspension of soil contaminated with plutonium, 

americium, and other radionuclides (e.g., 238Pu, 137Cs, and 237Np) needs to be 
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taken into consideration for soil contamination areas throughout the site, and 

should not be limited to the 903 Pad without some justification why other inactive 

waste sites (108 in all) are not included. SC&A also believes that resuspension of 

239+240Pu and 241Am throughout the site could be an important contributor to 

ambient dose for both monitored and unmonitored dose. In particular, the TBDs 

do not clearly address how internal dose assessments will consider the 

contribution of resuspended plutonium and americium to worker dose. 

[SC&A, 2005, p. 18] 

For clarification, the issues raised in this finding are broken out for review in the following 

subsections. 

5.1.1 Routine and episodic ambient airborne releases, including resuspension of 

contaminated soils

SC&A’s 2005 site profile review noted the following: 

The RFP environmental TBD excluded internal dose as a result of soil 

resuspension and focus[ed] its efforts on only one soil contamination area without 

justification. Soil contamination has been found at many areas on the Rocky Flats 

site, including in the East Spray Fields and the buffer zone. There is no 

explanation of why dose from radioactive material in soil excluded these other 

areas. The ambient air monitoring data is of questionable validity for use in 

assessing onsite worker environmental dose. Annual inhalation intake values 

developed from atmospheric modeling appear to be underestimated. [SC&A, 

2005, p. 119] 

NIOSH’s (2020b) revised TBD-4 prefaces its treatment of contaminated soil resuspension at 

RFP as follows: 

Total routine (nondiscrete) plutonium emissions from 1953 to 1989 are estimated

to be on the order of 0.12 Ci (Voillequé and Till [1999]). This estimate does not 

include releases due to resuspension of contaminated soil downwind of the 

903 Pad or resuspension of contaminated soil in other areas of the Plant due to 

deposition from the primary sources. Although the release of plutonium due to 

resuspension is not included in this estimate of routine emissions, it is addressed 

in this TBD as a contributor to exposure. [NIOSH, 2020b, p.12] 

NIOSH provides its specific treatment for estimating occupational environmental doses from 

resuspension of soil contaminants in the model in attachment A of TBD-4, revision 03: 

Resuspension of previously deposited isotopes also contributed to onsite air 

concentrations. The model for this analysis (described in Attachment A) 

addressed contributions from the primary sources in the Phase I study 

(ChemRisk 1992, [1994]) as well as resuspension. [NIOSH, 2020b, p. 12] 
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NIOSH further justifies its modeling approach as (1) claimant favorable for incidental releases 

and (2) conservative based on available site monitoring data, including monitoring by the 

Colorado Department of Public Health and Environment (CDPHE): 

After 1964, suspension or resuspension (Rood, Grogan, and Till 1999, p. 72) of 

contaminated soil was the main source of plutonium releases to onsite air. Air 

monitoring data provided either total long-lived alpha (TLLα) concentrations, 

from which 239/240Pu values could be derived, or actual measurements of 239/240Pu. 

The annual environmental reports . . . were useful in providing summaries of air 

concentrations by sampler location based on monthly reporting through 1994. 

After 1994, Rocky Flats Environmental Technology Site (RFETS) monitoring 

reports and the CDPHE monitoring reports provided quarterly summaries of 

monitoring results. Activity concentrations of 241Am were estimated after 1964 by 

assuming that the concentration of 241Am was 30% of the 239/240Pu concentration 

based on measurements of the 241Am/239Pu activity in RFP soil by three separate 

researchers (Poet and Martell 1972; Krey et al. 1976; Litaor and Allen 1996). This 

assumption is favorable to claimants because the average measured activity ratios

in soil were found to be less than 0.20 by these three groups of researchers. 

[NIOSH, 2020, pp. 12–13] 

SC&A finds that NIOSH’s revision of TBD-4 since the last version reviewed (revision 01; 

NIOSH, 2004e) has (1) added more specific information and guidance regarding the contribution 

of resuspension of soil contaminants for occupational environmental exposures and (2) provides 

better justification of its basis in available site monitoring data and the claimant favorability of 

the modeling provided. SC&A recommends that this issue be closed. 

5.1.2 Comprehensiveness, scope, and source data for environmental exposure pathway 

analysis

SC&A’s 2005 review made an observation about the lack of clear delineation of operational 

phases that was also of concern for this TBD analysis: 

Observation 2: The overlap in definition of phases of operation requires further 

study to identify dose from radionuclides such as tritium, thorium, enriched and 

depleted uranium 239+240Pu, 241Pu and 241Am which can be related to significant 

releases. A timeline is needed to distinctly delineate phases of operation, data 

types and availabilities, as well as data sources used. [SC&A, 2005, pp. 18–19] 

In its site profile review, SC&A (2005) noted a number of observed deficiencies or omissions in 

data-based parameters used as a basis for environmental pathway analysis to estimate 

occupational environmental dose. SC&A noted the following about accounting for operations 

and data type, adequacy, and completeness: 

The overlap in the definitions of the phases of production and studies requires 

additional explanation. SC&A, therefore, recommends presenting a timeline of 

these phases in conjunction with data types and availabilities, as well as data 

sources used in support of the TDB [NIOSH, 2004e]. The report was not clear if 

the definitions of the two phases in Section 4.2.1 are the same as in Section 4.2.2. 
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In addition, it seems that there is an overlap in the cutoff date (1992 and 1993) 

between the phases. No explanation was given for the basis of that overlap. In 

addition, the operational year in Section 4.2.1 [of TBD-4, rev. 01] was identified 

to have run until 1994, while Section 4.2.2 indicated that production ceased after 

1992. SC&A recommends that these relationships be made clearer through the 

RFP operational and post-operational years. [SC&A, 2005, p. 95] 

In its most recent revision to TBD-4 (rev. 03), NIOSH (2020b) has expanded its definition of the 

two phases (operational and post operational), providing additional information and bases, and 

has included attachment A to give more substantiation of source term, operations, and data 

adequacy and completeness. The revision also more precisely differentiates the two phases to 

avoid any overlap. On this basis, SC&A recommends closure of observation 2. 

Questions surrounding particle size are addressed, in detail, by an expanded section 4.2.3 in

TBD-4, revision 03, which gives the following guidance: 

The recommendation to assume an AMAD of 1.0 μm from 1970 through 1993 is 

based on the fact that air concentrations downwind of the 903 Area, which are 

better characterized by an AMAD of 5.0 μm, tended to be only slightly (less than 

an order of magnitude) higher than other onsite areas, but not always. In 1972, the 

onsite airborne concentrations downwind of the 903 Area were 2 to 3 times higher 

than in other areas of RFP (Dow 1972–1973). However, in 1990 to 1992, the air 

concentrations in the main production areas of RFP (northern section of the 

industrial zone) exceeded those downwind of the 903 Area. 

These assumptions are favorable to the claimant in the following respects: (1) for 

most organs, assuming an AMAD of 1.0 μm increases the dose by about a factor 

of 1.5 to 1.9 over the dose calculated by assuming an AMAD of 5.0 μm; and 

(2) using the sitewide maximum intakes, based on the highest annual average 

concentration for any given sampler location, often implicitly assumes the worker 

was exposed to the air concentrations downwind of the 903 Area, which was not 

the location of most exposures. The extrathoracic airways dose factor is a factor 

of 1.5 to 1.9 times higher for the AMAD assumption of 5 μm (the particle size 

more appropriate for resuspended plutonium) versus 1.0 μm (ICRP 2001). 

Therefore, for cases in which the extrathoracic airways [ET, ET1, ET2, LN(ET)] 

dose is of most interest, the AMAD of 5.0 μm should be assumed for all years. 

[NIOSH, 2020b, p. 16] 

SC&A finds that the additional specificity, justification, and information in TBD-4, revision 03, 

addresses the concerns identified in 2005 regarding the lack of such details in revision 01 of the 

TBD (NIOSH, 2004e). SC&A recommends that this issue be closed. 

5.1.3 Source data for dose estimation questionable based on effectiveness of air 

sampling

SC&A found that the “source data for calculation of airborne environmental dose is 

questionable, based on effectiveness of environmental air sampling” (SC&A, 2005, p. 115). 
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NIOSH acknowledges the limitations of relying on environmental air sampling prior to 1964 and 

has developed air dispersion modeling to account for those source terms. NIOSH provides a 

technical basis for the model in attachment A of the revised TBD-4, as it notes: 

Air concentrations of 239/240Pu and 241Am were estimated as described in 

Attachment A. Onsite air monitoring data are the preferred source of air 

concentrations (see Attachment A) for 239/240Pu, but in the early years (until 1964) 

such data were not sufficiently descriptive or complete to allow reliable estimates. 

Therefore, dispersion modeling results were used to estimate air concentrations of 

239/240Pu for these years. During these early years, stack or building vent emissions 

were the main source of plutonium to onsite air, and measurements of these 

releases are available. Resuspension of previously deposited isotopes also 

contributed to onsite air concentrations. The model for this analysis (described in 

Attachment A) addressed contributions from the primary sources in the Phase I 

study (ChemRisk 1992, [1994]) as well as resuspension. [NIOSH, 2020b, p. 12] 

As noted earlier, SC&A finds that use of dispersion modeling based on onsite CDPHE air 

monitoring measurements and founded on the technical basis in attachment A of the revised 

TBD satisfies SC&A’s original concerns about the use of those data. SC&A recommends closure 

of this issue. 

5.1.4 Need to clarify if maximum estimates of annual intakes are applied

In its 2005 site profile review, SC&A found that “It is not clear if the maximum or average 

estimates of annual intakes were applied in 1965–2002, and if the 50th percentile or the 95th

percentile values in Table 4-1 were used for dose reconstruction” (SC&A, 2005, p. 96). 

SC&A’s basis for this finding was as follows: 

In reference to work recently completed by the National Institute for Occupational 

Safety and Health (NIOSH) on the revised TBDs for Mallinckrodt and Bethlehem 

Steel, NIOSH has adopted the 95th percentile value from available data as the 

basis for filling in missing bioassay, air sampling, and external dosimetry data for 

claimants with missing data. This strategy represents a revision to previous 

strategies in which NIOSH often applied the entire distribution as a surrogate for 

missing data. As we have discussed in the past, we believe the latter approach can 

be characterized as claimant neutral, while the former approach appears to us to 

be more claimant favorable and more in keeping with the letter and intent of 

42 CFR Part 82. As such, we believe that the “95th percentile” approach be 

adopted in this TBD [NIOSH, 2004e] also. [SC&A, 2005, p. 96] 

In terms of whether the maximum or average estimates of annual intakes were applied for 1965–

2002, NIOSH’s changes in revision 02 of TBD-4 included (emphasis added) an “update [to]

Section 4.1.1 with standard NIOSH text, updated intakes to reflect sitewide maximum intakes

which required obtaining location-specific model output as opposed to location-averaged output” 

(NIOSH, 2007b, p. 2). Those changes remain in revision 03 (NIOSH, 2020b). 
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TBD-4, revision 03, also provides guidance on applying the “maximum annual median” air 

concentrations for intake calculations of plutonium (Pu)-239/240 and americium (Am)-241 in the 

following passages (emphasis added): 

To calculate intakes of 239/240Pu and 241Am, the estimated sitewide maximum 

annual median . . . air concentrations of these isotopes in the RFP environment 

were multiplied by an annual inhalation rate. The assumed breathing rate was 

3,000 m3 /yr, corresponding to an hourly rate for light activity of 1.2 m3 (based on 

ICRP Publication 66; 1994), and a 2,500-hr work year. Intake rates should be 

scaled to account for occupancy times other than 2,500 hr of exposure. [NIOSH, 

2020b, p. 12] 

Table 4-2 lists estimated annual intakes of 239/240Pu and 241Am from 1953 to 

1964, based on the atmospheric modeling described in Attachment A. The values 

are expressed in becquerels per year. The calculated intakes represent a 

maximum annual median (50th percentile) of the six computational nodes 

evaluated in the RFP industrial area for 500 Monte Carlo model realizations 

simulated for each year, and are exclusive of the buffer zone (Figure 4-1). 

[NIOSH, 2020b, p. 13] 

Table 4-3 lists estimated annual intakes of 239/240Pu and 241Am between 1965 and 

2005. The values for 239/240Pu in this table are based on sitewide maximum 

annual median measured concentrations at samplers across the site, and therefore 

represent concentrations at the locations of higher concentration (typically near 

the 903 Area). [NIOSH, 2020b, pp. 13–14] 

Table 4-1 in TBD-4, revision 01 (NIOSH, 2004e) listed 50th and 95th percentile average and 

maximum inhalation intake values for Pu-239/240 for 1953–1964. The revised TBD-4, 

revision 03, replaces that table with table 4-2, which provides “Sitewide maximum annual 

median inhalation intakes (Bq/yr) of 239/240Pu and 241Am based on atmospheric modeling, 1953 to 

1964” (NIOSH, 2020b, p. 13).

The preceding revisions in TBD-4, revisions 02 and 03 apply the “standard NIOSH text,” with 

(emphasis added) “updated intakes to reflect sitewide maximum intakes which required 

obtaining location-specific model output as opposed to location-averaged output” (NIOSH, 

2020b, p. 2). With the aforementioned table substitutions, and with “estimated annual intakes of

239/240Pu and 241Am between 1965 and 2005” (NIOSH, 2020b, p. 13) based on sitewide 

maximum annual median measured plutonium concentrations at samplers across the site 

(NIOSH, 2007b, 2020b), SC&A recommends closure of this issue. 

5.1.5 Resolution of finding 9

SC&A recommends closure of finding 9 regarding inadequacies in addressing potential 

environmental exposure from routine and ambient airborne releases and resuspension of 

contaminated soil. SC&A finds that NIOSH’s revision of TBD-4 (1) has added more specific 

information and guidance about the contribution of resuspension of soil contaminants for 

occupational environmental exposures and (2) provides better justification of its basis in 

available site monitoring data. The use of dispersion modeling based on both onsite and CDPHE 
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air monitoring measurements, with a technical basis provided in attachment A, gives further 

substantiation of source term, data availability, exposure pathway analysis, particle size, and 

uncertainties involved. 

5.1.6 Observation 3 – use of RATCHET air dispersion model

SC&A’s site profile review observed that: 

The use of the RATCHET air dispersion model is not able to take into account 

unexpected air flows around close-in buildings, where the height of those 

buildings may perturb estimates because of wake effects. This may be a 

confounding problem at RFP and needs to be addressed. [SC&A, 2005, p. 19] 

In its revision 03 to TBD-4, NIOSH discussed the issue of building wake effects on air 

dispersion modeling: 

However, the model application is such that building wake effects, a potential 

concern for areas close to the sources, are not significant for two reasons. First, 

releases from the Building 771 stack were not likely to be affected by building 

wakes because the 44-m stack is sufficiently high in relation to nearby buildings 

so that the plume was not significantly affected . . . . Second, all other elevated 

sources in the model were treated as area sources, such that initial dispersion was 

assigned, which implicitly accounts for the effects of building wakes. 

[NIOSH, 2020b, p. 40] 

Based on this explanation, SC&A is satisfied that this issue is addressed and recommends 

closure of this observation. 

5.2 Consideration of the FBI investigation on environmental dose reconstruction

In a September 4, 2013, memorandum, SC&A (SC&A, 2013) suggested that the work group 

consider the potential impact of the 1989 FBI investigation on the DR methods NIOSH

recommends in ORAUT-TKBS-0011-4, revision 02 (NIOSH, 2007b). SC&A provided 

additional details in a July 10, 2015, memorandum (SC&A, 2015a) concerning the need to 

consider the potential impact of the 1989 FBI investigation on DR. SC&A reviewed revision 03 

of ORAUT-TKBS-0011-4 (NIOSH, 2020b) to determine if the potential impact of the 1989 FBI 

investigation had been addressed and resolved. The following documents are relevant to this 

review: 

• ORAUT-TKBS-0011-4, revision 02 (NIOSH, 2007b) 

• SC&A’s September 4, 2013, memorandum, “SC&A Review of RFP Data Falsification 

Issue” (SC&A, 2013) 

• SC&A’s July 10, 2015, memorandum, “SC&A’s Current Status of Evaluating the RFP 

Potential Data Falsification, Handling Bioassays, and Document Destruction Issues” 

(SC&A, 2015a) 

• ORAUT-TKBS-0011-4, revision 03 (NIOSH, 2020b).
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In its July 2015 memorandum, SC&A (2015a) provided the page, table, and figure numbers in 

ORAUT-TKBS-0011-4, revision 02 (NIOSH, 2007b), that contained information that could 

potentially be impacted by environmental monitoring issues raised in the 1989 FBI investigation. 

SC&A reviewed the environmental intake information in TBD-4, revision 03 (NIOSH, 2020b),

compared to the environmental intake information in revision 02 (NIOSH, 2007b) concerning 

the pages, tables, and figures that SC&A (2015a) found could have been impacted by 

environmental monitoring results. SC&A found an approximately 25 percent increase in the 

recommended intake values in tables 4-2 and 4-3 of revision 03 compared to those in tables 4-2 

and 4-3 of revision 02. This increase was the result of basing the intake on 2,500 hours per year 

in revision 03 (section 4.2.3) compared to 2,000 hours per year in revision 02 (section 4.2.3). 

SC&A found that the numerical values in the tables and figures in attachment A of TBD-4,

revision 03 (NIOSH, 2020b), remained the same as in revision 02 (NIOSH, 2007b).

SC&A found that the potential impact of the 1989 FBI investigation concerning environmental 

monitoring for DR purposes is addressed in TBD-4, revision 03 (NIOSH, 2020b), in 

section 4.1.4, pages 9 and 10. The last bullet point and conclusion of section 4.1.4 state:

• A review of the Colorado Federal District Court Report of the Federal District 

Special Grand Jury ([Colorado Federal District Court] 1992) indicates that 

RFP had a number of violations. These included a deficient ground-water 

monitoring system, failure to notify government agencies of environmental 

law violations, storage issues, and chemical violations. However, the grand 

jury review of the FBI’s findings did not identify any deficiencies with the 

radiological monitoring programs (i.e., no deficiencies are assumed to exist 

with the external ambient data and/or environmental air data). 

Based on this information, the ORAU Team concluded this information has no 

effect on its ability to perform onsite ambient or environmental dose 

reconstructions with sufficient accuracy. [NIOSH, 2020b, p. 10]

SC&A reviewed the cited document, “Colorado Federal District Court Report of the Federal 

District Special Grand Jury 89-2 January 24, 1992” (Colorado Federal District Court, 1992), and 

found that the proposed violations were related to environmental issues, such as groundwater 

monitoring and the Clean Water Act, and not to the monitoring of workers’ environmental 

intakes; therefore, they would not impact DR as stated in ORAUT-TKBS-0011-4, revision 03 

(NIOSH, 2020b). 

SC&A finds this issue has been adequately addressed.

5.3 Summary and conclusions for TBD-4

SC&A’s review of TBD-4, revision 03 (NIOSH 2020b), on occupational environmental dose, 

found that the revised TBD addressed and resolved SC&A’s finding 9 from its original 2005 site 

profile review regarding inadequacies in addressing potential environmental exposure from 

routine and ambient airborne releases and resuspension of contaminated soil at RFP. SC&A 

found that NIOSH has added more specific information and guidance about the contribution of 

resuspension of soil contaminants for occupational environmental exposures and provides better 
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justification of its basis in available site monitoring data. Therefore, SC&A recommends closure 

of this finding. 

SC&A likewise found satisfactory the treatment by the revised TBD-4 of other issues, such as 

use of the Regional Atmospheric Transport Code for Hanford Environmental Tracking 

(RATCHET) air dispersion model and consideration of environmental DR issues stemming from 

the 1989 FBI investigation. SC&A also performed a general review of TBD-4, revision 03, and 

did not identify any additional findings.

6 Review of TBD-5 Occupational Internal Dose, ORAUT-TKBS-0011-5, 

Rev. 04

The following documents are relevant to this review: 

• ORAUT-TKBS-0011-5, revision 00 (NIOSH, 2004c) 

• SCA-TR-TASK1-0008, revision 0 (SC&A, 2005) 

• ORAUT-TKBS-0011-5, revision 04 (NIOSH, 2020c) 

In its original site profile review for RFP, SC&A (2005) raised issues related to high-fired 

plutonium and uranium; DR guidance for neptunium, thorium, curium, tritium, and other source 

terms identified; additional information for radionuclide solubility and particle size; and 

guidance for wound and ingestion pathways. SC&A reviewed the most recent occupational 

internal dose TBD, TBD-5, revision 04 (NIOSH, 2020c), for its (1) consideration and resolution 

of issues raised in SC&A’s 2005 site profile review, (2) reflection of site profile issues identified 

during work group proceedings, and (3) treatment of SEC issues that had been closed out by the 

work group but were considered relevant as “site profile” issues and were to be addressed as 

such. 

Based on these considerations, SC&A reviewed the following issues for TBD-5, revision 04 

(NIOSH, 2020c): 

• Finding 1: “Suggested use of urine bioassay MDA values for plutonium and americium 

appear low and are likely to yield body burdens/organ doses that are proportionately low 

and, therefore, claimant unfavorable.” (SC&A, 2005, p. 15 and section 5.1) 

• Finding 2: “Internal dosimetry TBD lacks definitive direction in some instances and has 

gaps that need to be addressed.” (SC&A, 2005, p. 15 and section 5.2) 

• Finding 7: “The internal TBD does not consider potential contribution of ingestion 

pathway.” (SC&A, 2005, p. 17 and section 5.3) 

• Observation 4: “With an appropriate wound dose model not available, the cited approach 

for estimating wound-related uptakes in the internal dose TBD is claimant favorable for 

relevant types of cancer, except for lymph nodes and skin cancers. A more claimantfavorable approach for these affected organs needs to be addressed, for which a recently 
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proposed model (Guilmette and Durbin 2003) for wound-site retention of soluble 

radionuclides may be relevant.” (SC&A, 2005, p. 19 and section 5.2.7) 

• Critical Mass Laboratory (CML) intakes concerning DR: This issue had been evaluated 

by NIOSH in a white paper, “Reassessment of Internal Radiation Dose from Sources at 

the Rocky Flats Plant Critical Mass Laboratory,” revision 0 (NIOSH, 2016). 

• Evaluation of the potential for internal dose from Np-237: This concern stemmed from an 

existing SEC issue from NIOSH’s evaluation report for Petition-00192 (NIOSH, 2013). 

• Reported presence of Mg-Th alloy: This issue originated from comments by SC&A, 

NIOSH, and petitioners during the work group’s review of NIOSH’s evaluation report for 

SEC Petition-00192 (ABRWH, 2006b, 2006c, 2007). 

• Tritium exposure issues: This issue was raised by petitioners as part of the RFP work 

group’s review of NIOSH’s evaluation report for SEC Petition-00192 (ABRWH, 2013). 

SC&A reviewed these issues as described in the following sections. SC&A used NIOSH white 

papers and reports, SC&A reviews, and RFP work group meeting transcripts to establish issue 

descriptions, assessments, and the status of work group resolutions and closures. 

6.1 Suggested use of urine bioassay MDA values appear low

SC&A noted the following in finding 1 of its site profile review (SC&A 2005, p. 15): 

Suggested use of urine bioassay MDA values for plutonium and americium 

appear low and are likely to yield body burdens/organ doses that are 

proportionately low and, therefore, claimant unfavorable. NIOSH’s use of 

median MDA (minimum detectable activity) values for plutonium and americium 

appear unduly low and likely to yield body burdens or organ doses that would be 

non-conservative, given the uncertainties involved. Given the limited data and 

uncertainties of the key variables (e.g., sample count time, detector counting 

efficiency, self-absorption, and various sampling assumptions) from which MDAs 

are defined, SC&A understands the need to apply certain assumptions to bridge 

these gaps in information. However, the concern is that a number of these 

assumptions are not adequately supported and may not be claimant favorable. 

Likewise, the use of these assumed median MDA values, themselves, in dose 

reconstruction, may be inappropriate. This is because urine activity levels 

monitored at RFP for plutonium and americium were likely well in excess of 

assumed median MDA values, most notably where workers were assigned “zero” 

or “background” readings in the past when urinalysis results were found to be less 

than 10% of the tolerance level. SC&A believes more conservative assumptions 

should be applied in the formulation of MDA values that would more realistically 

reflect the range of uncertainties involved. 

The urinalysis MDA values in TBD-5, revision 04, tables A-11 and A-12 (NIOSH, 2020c, p. 82), 

for plutonium are the same as the MDA values in the corresponding tables on pages 46 and 47 of 

TBD-5, revision 00 (NIOSH, 2004c). The urinalysis MDA values in tables A-18 and A-19 
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(pp. 84, 85), for americium in TBD-5, revision 04, are the same as the MDA values in the

corresponding tables on page 49 of TBD-5, revision 00. However, SC&A reviewed the 

post-2004 TBD-5 documents for three other major DOE sites (Los Alamos National Laboratory

(LANL), Hanford, and Oak Ridge National Laboratory(ORNL)) for plutonium and americium 

MDA values and found the MDA values recommended for RFP to be in most instances in the 

same range, or larger, than for other sites. Additionally, the RFP TBD-5 provides for extreme 

conditions (95th percentile) (table A-12 for plutonium and table A-19 for americium) for the 

dose reconstructor to use if needed. SC&A finds that this issue has been addressed and 

recommends closure.

6.2 TBD lacks definitive direction in some instances

In Finding 2 of its 2005 review of NIOSH’s TBD, SC&A found: 

Internal dosimetry TBD lacks definitive direction in some instances and has 

gaps that need to be addressed. There is limited guidance for use by the dose 

reconstructor regarding the process and assumptions that should be used to 

calculate internal dose. Notably, this TBD does not provide clear guidance for 

assessment of dose for unmonitored workers, nor does it specifically address what 

“missed dose” may exist and how it is to be addressed. The use of the assumed 

default particle size of 5 μm AMAD needs to be reconsidered for those RFP 

operations for which actual particle size measurements exist (e.g., a 0.3 μm mass 

median diameter for airborne particles involved in at least two fires at RFP). The 

approaches regarding solubility need to be reviewed, particularly for Type “S” or 

“Super-S” plutonium compounds whose high insolubility may lead to more 

exposure to gastrointestinal and respiratory tract organs. Uncertainties are not 

addressed in the TBD regarding the 241Am assay of plutonium processed at RFP 

and how lung counting was calibrated to these values. The assumptions (full 

equilibrium) regarding the methodologies to assess the internal exposure to 

depleted uranium based on estimates of 238U activity may not be claimant 

favorable for some circumstances. The sensitivity of the bioassay methods was 

not adequate to detect incidental intakes of insoluble compounds. 

[SC&A, 2005, p. 15] 

The following subsections describe SC&A’s review of TBD-5, revision 04 (NIOSH, 2020c), for 

these issues compared with SC&A’s (2005) discussion of revision 00 (NIOSH, 2004c).

6.2.1 SC&A (2005) section 5.11.3 – completeness of internal monitoring data

In its original review of the 2004 internal dose TBD, SC&A (2005) found that TBD-5 used 

several techniques to assign dose in the case of an unmonitored worker. To calculate internal 

dose for workers not involved in an incident, revision 00 of TBD-5 provided the following 

guidance (NIOSH, 2004c, p. 30): 

The suggested approach is to estimate the time spent by the worker in a building 

involved in a radionuclide of interest and credit the worker with a chronic intake 

at an arbitrary fraction of the in-plant guide (or official limit), whichever is more 

claimant favorable. . . . 
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Claims files may include event-specific data that should be used to reconstruct 

internal dose. When such data is not available default assumptions may be made.

SC&A (2005, p. 105) noted: 

In the case of an unmonitored worker not involved in an incident but having 

access to radiological areas, it is not clear whether the method outlined is 

bounding. Information, such as job title, work location, skill or task, time spent in 

an area, and radionuclides of concern are not readily available and would have to 

be evaluated for the particular individual. The process for assigning dose to an 

individual in multiple job locations would further complicate the matter. In the 

case of an incidental exposure, not collecting samples in a timely manner may 

prevent dosimetry from collecting needed follow-up samples, or render bioassay 

techniques ineffective (e.g., insoluble plutonium). 

In reviewing TBD-5, revision 04 (NIOSH, 2020c), SC&A finds that NIOSH reflects the SEC 

determination for Petition-00193 and has defined an SEC class for all workers at RFP, as follows 

(NIOSH, 2020c, p. 18): 

NIOSH has determined that doses to unmonitored RFP workers from neptunium, 

thorium, and 233U (and its associated 232U and 228Th progeny) cannot be 

reconstructed from April 1, 1952, through December 31, 1983, inclusive (NIOSH, 

[2013]). 

The class includes all workers during the SEC period. Because of the identified 

dose reconstruction infeasibility, all dose reconstructions for monitored workers 

during the SEC period are considered partial dose reconstructions. 

For potential tritium exposures, NIOSH has added attachment G to TBD-5, revision 04, as a 

basis for assigning tritium doses to unmonitored RFP workers. 

For the application of an internal co-exposure model for unmonitored workers other than for the 

radionuclides discussed in this section, NIOSH added attachment D to revision 04 of TBD-5 

(NIOSH, 2020c). Attachment D notes that the RFP work group “suggested and agreed that the 

use of the 95th percentile internal co-exposure intake for unmonitored workers with nontrivial 

exposure potential would satisfy [the work group’s] concern” that “the number of samples in 

HIS-20 and CEDR [electronic datasets] were different in some cases,” thereby raising questions 

about a comparison using the epidemiology-based CEDR urinalysis dataset as a means to 

validate the HIS dataset for RFP (NIOSH, 2020c, p. 145). 

Based on these changes, SC&A finds that NIOSH has addressed the original issue of 

reconstructing internal dose for unmonitored workers and recommends closure of this issue. 

6.2.2 SC&A (2005) section 5.2.3 – default particle size

SC&A found that the “use of the assumed default particle size of 5 μm AMAD needs to be 

reconsidered for those RFP operations for which actual particle size measurements exist (e.g., an 

0.3 μm mass median diameter for airborne particles involved in at least two fires at RFP, which 
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may be typical of ‘high-fired’ plutonium generated in processes involving temperatures 

exceeding 400°–600° C)” (SC&A, 2005, p. 12). 

NIOSH addressed this issue by providing specific guidance on the application of smaller particle 

sizes for workers potentially exposed to plutonium fires at RFP. NIOSH noted that: 

In general, particle size and distributions are not available for work areas or 

incidents at RFP. Therefore, dose reconstructions should use the default value of 

5-μm activity median aerodynamic diameter (AMAD) (NIOSH 2002). 

One exception is the plutonium fire on October 15, 1965, in Buildings 776 and 

777 (Dow 1965), for which Mann and Kirchner (1967) measured a mass median 

diameter of 0.3 μm (1-μm AMAD) with a geometric deviation of 1.83. Therefore, 

for individuals potentially involved with a plutonium fire, the more favorable 

particle size of 1-μm or 5-μm AMAD should be assumed. [NIOSH, 2020c, p. 22] 

Based on the provision of more specific guidance on the application of smaller particle size, 

SC&A recommends this issue be closed. 

6.2.3 SC&A (2005) section 5.2.1 – type S and Super S solubility

SC&A found that the manner in which the TBD approaches solubility needs to be reviewed, 

particularly for type S or Super S plutonium compounds whose high insolubility may lead to 

more exposure to gastrointestinal and respiratory tract organs. At Rocky Flats, high-fired oxides 

were generated during the two big fire accidents and more than likely as a result of smaller 

plutonium fires and high-temperature processes in furnaces, incinerators, and production areas. 

SC&A’s (2005) review evaluated the effect of using the high-fired plutonium (Super S) lung 

retention parameters in the interpretation of bioassay results by using the type S Pu-239 lung 

retention parameters in simulating different scenarios. This analysis showed that: 

the incidental acute intake of insoluble plutonium compound, in the first 20 years, 

may be difficult to identify because of several factors, including the relatively 

high MDA value (0.01 Bq), the low fraction of activity intake excreted through 

the urine (10-6 Bq), and historic delay in or lack of performing post-incident 

urinalysis or fecal analysis. It was found that the contribution of chronic intake in 

urinary activity increases over the time of exposure, obviating the detection of 

incidental intakes, unless the activity is extremely high or the chronic exposure is 

very low, or undetectable. [SC&A, 2005, p. 41] 

In its 2020 internal dose TBD revision, NIOSH provided specific information and guidance 

regarding assumed insolubility for plutonium: 

The plutonium on , in Buildings , is a special 

case. The plutonium, which was strongly retained in the of exposed workers 

with relatively low transfer to the urine, exhibited highly insoluble (type SS) 

characteristics ([NIOSH, 2020d]). 
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Plutonium in chemical processing operations can be either soluble (type M), 

insoluble (type S), highly insoluble (type SS), or a mixture of solubilities. Dose 

reconstructors should select the material type that is most favorable to the 

claimant ([NIOSH, 2018b]). count data in conjunction with urine data can 

help to determine absorption type. [NIOSH, 2020c, p. 22] 

SC&A agrees with this guidance and recommends closure of this issue. 

6.2.4 SC&A (2005) section 5.2.6.2 – calibration of lung counting to Am-241

SC&A (2005) found that the TBD did not address uncertainties regarding the Am-241 assay of 

plutonium processed at RFP and how lung counting was calibrated to these values. SC&A 

(2005) noted that the TBD (NIOSH, 2004c, p. 18) stated the following: 

Reporting levels are not easily defined, because quantification was preceded by 

verification counts and professional judgments. In addition, before 1974, the 

practice was not to quantify a positive detection of 241Am unless the deposition 

could be associated with a known incident with a known ppm 241Am. Affected 

workers were classified as positive unknowns or some variation. Starting in 1974, 

the practice was changed to quantify the plutonium depositions for positive 

unknowns by assuming a default value of 1,000 ppm 241Am on the date of the 

most likely intake or on the date of the first positive lung count. The ppm 241Am 

was then calculated for the date of the lung count to account for the ingrowth of 

241Am from the nuclear transformation of 241Pu and the radioactive decay of the 

initial 241Am.

SC&A found, however, that “There is no clear instruction on how the dose reconstructors should 

choose the appropriate value of ppm 241Am, and also there is no clear explanation of the basis to 

choose 1,000 ppm as the default value for ppm 241Am” (SC&A, 2005, p. 54). 

NIOSH’s (2020c) revision of the internal dose TBD added an attachment B, “Minimum 

Detectable Amounts for in vivo Lung Counts,” which provides calibration factors for various 

historical detection systems, including MDA conversion factors for values of parts per million 

(ppm) Am-241 and Am-241 ingrowth in plutonium. Based on this detailed calibration and MDA 

information applicable to various detection systems used during RFP’s operational history, 

SC&A recommends closure of this issue. SC&A did find that table B-11, page 104, lacks units 

for the MDA values; it appears that it should specify the unit of nanocuries. 

6.2.5 SC&A (2005) section 5.2.6.2 – assumptions of full equilibrium for depleted 

uranium

SC&A found that “The assumptions (e.g., full equilibrium) regarding the methodologies to 

assess the internal exposure to depleted uranium based on estimates of 238U activity may not be 

claimant favorable for some circumstances” (SC&A, 2005, pp. 12–13). For example, SC&A 

pointed out that “If the worker is exposed to depleted uranium metal with a deficiency of 234Th, 

the assumption of equilibrium will underestimate the 238U activity in the lung of the workers 

exposed to depleted uranium metal with a deficiency of 234Th” (SC&A, 2005, p. 55).
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In its most recent version of TBD-5 for internal dose, NIOSH indicates:

The major uncertainty is the assumption of equilibrium of the 234Th with the 238U 

before 1990, when DU was still being processed. Part of the process was to 

remove decay chain radionuclides, especially thorium, by heating the uranium 

ingot to drive the smaller atoms of thorium to the surface or top of the ingot, 

which was then cut off. The result was DU metal with a deficiency of 234Th for 

several weeks plus scrap DU with an excess of 234Th (super-equilibrium). The 

assumption of equilibrium when super-equilibrium existed is favorable to 

claimants. If a superequilibrium situation was operative and the 234Th lung count 

result was used to calculate the DU assuming equilibrium, the calculated DU 

would be higher than the actual activity. Therefore, the approach is favorable to 

claimants. The effect of a deficiency of 234Th (not favorable to claimants) is 

mitigated by the rapid ingrowth of the 234Th into the DU. Fifty-percent 

equilibrium occurs after 24 days after a thorium strike, and 90% occurs after 

80 days. [NIOSH, 2020c, p. 36] 

Based on NIOSH’s addition of these considerations regarding claimant favorability, SC&A 

recommends closure of this issue. 

6.2.6 SC&A (2005) section 5.2.1 – sensitivity of bioassay methods to detect incidental 

intakes of insoluble compounds

SC&A pointed out this issue, as it pertains to plutonium, based on an “evaluation of the effect in 

using the high-fired plutonium (Super S) lung retention parameters in the interpretation of 

bioassay results was carried out using the Type S 239Pu lung retention parameters simulating 

[four] different scenarios” (SC&A, 2005, p. 40), as detailed in attachment 9 of its 2005 site 

profile review. SC&A found that: 

This analysis shows that the incidental acute intake of insoluble plutonium 

compound, in the first 20 years, may be difficult to identify because of several 

factors, including the relatively high MDA value (0.01 Bq), the low fraction of 

activity intake excreted through the urine (10-6 Bq), and historic delay in or lack 

of performing post-incident urinalysis or fecal analysis. It was found that the 

contribution of chronic intake in urinary activity increases over the time of 

exposure, obviating the detection of incidental intakes, unless the activity is 

extremely high or the chronic exposure is very low, or undetectable. 

[SC&A, 2005, p. 41] 

TBD-5, revision 04 (NIOSH, 2020c), section 5.2.1.2 (p. 22), recommends assigning plutonium 

with a solubility type that is most claimant favorable per ORAUT-OTIB-0060, revision 02 

(NIOSH, 2018b), and ORAUT-OTIB-0049, revision 02, “Estimating Doses for Plutonium 

Strongly Retained in the Lung” (NIOSH, 2020d). These recommendations include consideration 

of type Super S plutonium. Both of these technical information bulletins were issued after 

revision 00 of TBD-5 (NIOSH, 2004c) was issued, which was the version SC&A (2005) had 

originally reviewed. SC&A finds this issue resolved and recommends closure. 
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6.3 TBD does not consider potential contribution of ingestion pathway

SC&A’s finding 7 from its 2005 site profile review is as follows:

The internal TBD does not consider potential contribution of ingestion 

pathway. The internal dose potential for ingesting radionuclides has not been 

considered in the occupational internal dosimetry TBD ([NIOSH, 2004c]). The 

ingestion pathway should not be ignored, except for the organs related to the 

respiratory tract where the dose from inhalation predominates. For other organs, 

ingestion dose is often higher than any dose received from inhalation. This is 

particularly true for plutonium, americium, and uranium. The ingestion pathway 

was also not considered in the derivation of co-worker dose data. The use of 

bioassay results to back-calculate intake and doses will produce higher internal 

exposures for certain organs if the ingestion pathway is taken into account. 

[SC&A, 2005, p. 17] 

SC&A concluded that the TBD does not provide adequate guidance for DR associated with 

tritium, neptunium, thorium, curium, noble gases, and fission products. Ingestion exposure 

pathways were not considered in the TBD in the dose assessment process, especially for cancers 

of the gastrointestinal tract. TBD-5 only refers to ORAUT-OTIB-0060, revision 02 (NIOSH, 

2018b), on page 22, in reference to selecting solubility type. ORAUT-OTIB-0060 addresses 

ingestion intakes on pages 16 and 38, all of which refer to OCAS-TIB-009, revision 0 (NIOSH, 

2004f). TBD-5 should include recommendations for ingestion intakes or direct reference to the 

appropriate ingestion-intake-related document. Although this issue has been resolved in practice, 

ingestion intakes should be addressed in TBD-5 with reference to OCAS-TIB-009. Therefore, 

SC&A recommends that this issue remain open until appropriate revisions are made in TBD-5. 

6.4 Available proposed wound dose model may be more claimant favorable

In observation 4 of its 2005 site profile review, SC&A noted: 

With an appropriate wound dose model not available, the cited approach for 

estimating wound-related uptakes in the internal dose TBD is claimant favorable 

for relevant types of cancer, except for lymph nodes and skin cancers. A more 

claimant-favorable approach for these affected organs needs to be addressed, for 

which a recently proposed model (Guilmette and Durbin 2003) for wound-site 

retention of soluble radionuclides may be relevant. [SC&A, 2005, p. 19] 

NIOSH’s (2020c) internal dose TBD-5 notes that guidance on assessing wound intakes is 

provided in ORAUT-OTIB-0022, revision 00, “Guidance on Wound Modeling for Internal Dose 

Reconstruction” (NIOSH, 2005). This updated guidance references Guilmette and Durbin 

(2003), as well as other assessments; therefore, it addresses SC&A’s 2005 observation. 

6.5 Critical Mass Laboratory intakes concerning dose reconstruction

The purpose of this review was to determine if the potential internal exposures from the CML 

had been addressed in revision 04 of ORAUT-TKBS-0011-5 (NIOSH, 2020c). SC&A had 

reviewed NIOSH’s evaluation of the potential exposure from mixed fission and activation 
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products (MFAPs) at the CML as detailed in previous reports. Documents relevant to the review 

of the CML in this context are as follows: 

• NIOSH’s June 9, 2015, white paper, “Assessment of Sealed Radioactive Sources, and 

Fission and Activation Products as Radiological Exposure Sources in the Rocky Flats 

Plant Critical Mass Laboratory (Building 886 Cluster)” (NIOSH, 2015a) 

• SC&A’s July 8, 2015, report, “Review of NIOSH’s White Paper: Assessment of Sealed 

Radioactive Sources, and Fission and Activation Products as Radiological Exposure 

Sources in the Rocky Flats Plant Critical Mass Laboratory (Building 886 Cluster)” 

(SC&A, 2015b) 

• NIOSH’s November 28, 2016, white paper, “Reassessment of Internal Radiation Dose 

from Sources at the Rocky Flats Plant Critical Mass Laboratory” (NIOSH, 2016) 

• SC&A’s 2017 report, SCA-TR-2017-SEC003, revision 0, “SC&A’s Evaluation of 

NIOSH’s White Paper, ‘Reassessment of Internal Radiation Dose from Sources at the 

Rocky Flats Plant Critical Mass Laboratory,’ of November 28, 2016” (SC&A, 2017) 

These NIOSH and SC&A RFP documents determined that there was not a potential for the 

internal intake of dosimetrically significant MFAPs. This is summarized by NIOSH in its 2016 

white paper (p. 36): 

NIOSH concludes that no significant personnel dose to Rocky Flats workers or 

contractors resulted from the generation of fission or activation products in the 

uranyl nitrate fuel or resuspended contamination from fuel spills as a result of 

criticality experiments conducted at CML over its lifetime.

SC&A’s (2017) evaluation of NIOSH’s (2016) white paper concurred (SC&A, 2017, p. 8):

Various parameters and scenarios could be used to estimate the potential MFAP 

intakes at the CML, with differing results. However, as indicative of the very 

small MFAP doses derived by both NIOSH and SC&A, even a change of a factor 

of 10 or 100 in the results would not alter the conclusions that the potential doses 

from MFAP were very small, and much less than 1 mrem, the minimum dose 

used in dose reconstruction. 

Revision 04 of TBD-5 (NIOSH, 2020c, p. 26) addressed the CML as follows: 

Building 886 housed the Critical Mass Laboratory (CML) at RFP. Mixed fission 

and activation products (MFAPs) in both the fuel and containment materials 

present an internal dose potential for personnel who might ingest or inhale them. 

CML staff submitted routine bioassay (urinalysis and whole-body counts) to 

detect intakes of plutonium, uranium, and/or americium, but MFAPs were not 

routinely monitored. 

Attachment H provides a detailed analysis of the CML. Based on this analysis, no 

significant unmonitored exposure is associated from the generation of fission or 

activation products. 
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Attachment H of ORAUT-TKBS-0011-5 (NIOSH, 2020c) contains approximately the same 

analysis as NIOSH’s 2016 white paper and reaches a similar conclusion: 

Based on this modeling, no significant personnel dose to RFP workers or 

contractors resulted from the generation of MFAPs in the UNH fuel or 

resuspended contamination from fuel spills as a result of criticality experiments at 

CML over its lifetime. [NIOSH, 2020c, p. 245] 

SC&A concurs with this assessment, as summarized in SC&A’s (2017) report, page 8. 

SC&A finds that the potential intake of MFAPs from the CML has been included in revision 04 

of ORAUT-TKBS-0011-5 (NIOSH, 2020c) and that this item has been adequately addressed. 

6.6 Evaluation of the potential for internal dose from neptunium-237

The purpose of this review was to determine if the potential internal exposures from Np-237 had 

been addressed in revision 04 of TBD-5 (NIOSH, 2020c), the details of which are presented in 

attachment E of that TBD. 

SC&A reviewed a January 8, 2015, NIOSH white paper, “Evaluation of the Potential for Internal 

Dose from Np-237 at the Rocky Flats Plant after 1983,” revision 1 (NIOSH, 2015b). SC&A also 

participated in some of the early data capture reviews at the Environmental Management 

Consolidated Business Center and DOE Legacy Management facility in Denver, CO, as well as 

in most of the interviews conducted with former RFP workers who had some involvement in or 

knowledge of neptunium operations. 

NIOSH’s (2015b) white paper examined neptunium operations at RFP and compared the period 

1962 through 1983 with the period after 1983. For the period after 1983, document reviews and 

interviews have uncovered only one neptunium operation: an approximately 1-year campaign in 

the mid-1980s that processed plutonium scrap containing residual amounts of neptunium in order 

to recover neptunium and purify plutonium (resulting in the purification of 58,282 grams of 

plutonium). Key attributes of this operation (plutonium-neptunium separation and residue 

recovery) were (1) the processing of the Pu/Np scrap in a “closed” separation system involving a 

glovebox containing a “wet” section (for aqueous processes) and a “dry” section (for calcining 

precipitates and weighing powders) separated by an air lock, with tanks containing feed material 

(plutonium and neptunium nitrate solution) being piped directly into the gloveboxes, and (2) lack 

of any “pure” plutonium or neptunium source term (both metals were produced with impurities 

of the other, i.e., “purified” plutonium contained 0.0069 percent neptunium and “purified” 

neptunium was co-generated with plutonium at a Pu:Np mass ratio of 6.4) (NIOSH, 2015b, p. 4).

The implication of the first attribute of this particular operation is that no routine exposure 

potential would have existed for workers performing the extractions at the glovebox. The 

implication of the second attribute is likewise important, in that the continuing presence of 

plutonium with neptunium product provides a means for radiological monitoring of this 

operation, given the much greater specific activity attributable to plutonium compared to

neptunium, making any uptake of the Pu/Np mixture detectable via bioassay results (all 

personnel were provided routine bioassays during this operation). 
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Beyond the one post-1983 neptunium operation identified, NIOSH (2015b) observes that 

neptunium was present at RFP from 1962 to 2003, with quantities ranging from 29 grams to 

1,318 grams (Idaho Completion Project, 2005). While the one post-1983 neptunium program 

was reportedly terminated by 1988, neptunium remained in inventory and as residual 

contamination in gloveboxes, ductwork, and other process equipment. In its review of an 

interview with a former RFP (ORAU, 2014), NIOSH concluded that for post-1983 

handling of this contaminated equipment (e.g., during decontamination and decommissioning 

(D&D) and site closure activities), it does not “dispute the potential for personnel Np exposures,” 

but “contends that the exposure would be dominated by the Pu (nothing involved purified or pure 

Np), and nothing provided up to this point disputes that contention” (ORAU, 2014, p. 9). In 

summary, NIOSH (2015b) concludes that there is “no evidence that Np-237 intakes occurred at 

RFP after December 31, 1983,” and that if intakes did occur after 1983 from the single 

neptunium operation that was identified, “the resulting organ doses would be adequately 

accounted for by the available Pu bioassay data” (NIOSH, 2015b, p. 10).

In its May 29, 2015, response to the NIOSH (2015b) white paper, SC&A (2015c) concurs with 

NIOSH that only one processing operation in the post-1983 period involved neptunium: the 

Plutonium-Neptunium Separation and Residue recovery operation, which ran from late 1985 to 

the end of 1987. Other activities at RFP involved neptunium contamination, including 

radioactive waste handling and later D&D, but in all of these instances, there is no evidence to 

date that neptunium source terms existed without the presence of plutonium. SC&A concurs with 

NIOSH that the co-presence of neptunium with plutonium enables radiological monitoring to 

account for any neptunium exposure component in a claimant-favorable manner. All workers 

involved with this one post-1983 operation, as well as other work activities in Building , 

were routinely bioassayed for plutonium intakes during the years in question (as were 

radiological waste handlers and D&D workers). Pure neptunium metal forms were stored and 

transported, but no internal intake (e.g., from surface oxidation) would have been likely, and 

none was detected through routine bioassay monitoring. 

The assessment and conclusions in revision 04 of TBD-5 (NIOSH, 2020c) reflect these SC&A 

findings and conclusions, and SC&A concurs with this TBD revision. 

6.7 Reported presence of magnesium-thorium alloy

The purpose of this review was to evaluate how the presence of Mg-Th alloys was addressed in 

revision 04 of TBD-5 (NIOSH, 2020c), the details of which NIOSH presents in attachment F.

SC&A originally raised the possibility of Mg-Th alloy being received by RFP during its SEC 

evaluation report review for Petition SEC-00030. In this review, SC&A found that “it is clear 

from NUREG-1717 and the other considerations presented above that knowledge of the 

approximate quantities, periods, and processing status of the magnesium-thorium alloy is needed 

before any reliable conclusions can be arrived at regarding doses to Rocky Flats workers from 

this material” (SC&A, 2007, p. 466).

During this review, SC&A interviewed a Dow Madison worker who had claimed that shipments 

of Mg-Th alloy material were being sent to Rocky Flats during a 12-year period from 1963 to 

about 1975 (SC&A, 2007, p. 491-497). At the Rocky Flats Work Group request, NIOSH 

subsequently interviewed four site experts from RFP regarding the degree of exchange of Mg-Th 
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between RFP and Dow Madison, if any. As noted in NIOSH’s August 13, 2014, response paper 

(NIOSH, 2014b), the four experts interviewed did not recall any large quantities of magnesium 

alloy in use at RFP and did not recall any shipments of such material between RFP and Dow 

Madison. 

The issue was raised again by the petitioner for petition SEC-00192 via e-mail on May 31, 2013, 

which indicated that a third party had reported that Mg-Th alloy plates had been brought to RFP, 

refined in Building 881, and then sent to the Transportation Modification (MOD) center for 

modification to fit “Semi Trucks” to make them bullet proof (NIOSH, 2014b, p. 2). NIOSH 

conducted a further records review of the Site Research Database (SRDB) to locate any 

documentation establishing a link between Mg-Th alloy and RFP, conducted new keyword 

searches of available RFP documents (e.g., using “HK-31” and “HK-31A” as key search 

parameters), performed additional onsite document searches, and interviewed additional former 

RFP workers, in particular, one who worked at the MOD center. None of those investigations 

surfaced new information, which has led NIOSH to change its original conclusions from 2007 

that there is no evidence of the use of Mg-Th alloy material at RFP. NIOSH opined that there is 

likely “confusion between RFP and other Denver-area sites, as well as confusion regarding 

Mg-Th alloy plates and other similar materials at RFP” (NIOSH, 2014b, p. 8).

While SC&A’s (2014) review of NIOSH’s (2014b) response paper identified a need at that time 

for additional investigation of the issue of Mg-Th receipt and use at RFP, SC&A also concluded 

that the value of that effort would need to be weighed by the work group against the resources 

required to investigate the remaining records, if they could even be identified at that stage. The 

reported Mg-Th use period for the Atomic Energy Commission weapons complex (1956–1969; 

ABRWH (2008)) falls within the current SEC period for RFP (1952–1983) and, therefore, would 

only influence partial DRs. While the reported concentration of thorium in the alloy material 

(2 percent–3 percent) is relatively low, SC&A concluded that the dose contribution to workers, if 

they were involved with certain intrusive handling of the material (e.g., grinding, smelting, or 

fabricating), could potentially be significant, as pointed out by SC&A’s 2007 review of NUREG 

-1717 and potential worker exposures from 4 percent thoriated welding rods (SC&A, 2007). 

The work group ultimately closed this issue. SC&A concurs with NIOSH’s conclusion in 

revision 04 of ORAUT-TKBS-0011-5 that, based on the research performed for this assessment, 

there is no corroborating evidence for the use of Mg-Th at the RFP site. 

6.8 Tritium issues

The purpose of this review was to assess how the potential for tritium exposure at RFP was 

addressed in revision 04 of ORAUT-TKBS-0011-5 (NIOSH, 2020c), as detailed in attachment G 

of the TBD, based on issues raised within the work group since the previous version of the TBD. 

In revision 04, NIOSH (2020c, p. 217) noted: 

Although tritium was used as a boost gas in weapons and as target material in 

neutron generators, it was not processed or handled in significant quantities at 

RFP. Tritium was monitored in the environment around the site for a time, but 

that monitoring ceased and was left to the State of Colorado for a brief period 

before an environmental release that occurred in April 1973. No analytical records 
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have been found that might help establish the RFP workplace tritium environment 

before 1973. 

NIOSH and SC&A exchanged a series of white papers to support work group discussions of this 

subject, culminating in a December 28, 2015, response by NIOSH, “Follow-up Efforts on 

SEC-00192, Rocky Flats Plant Tritium Issues,” revision 3 (NIOSH, 2015c), to address work 

group and SC&A comments on revision 2 (NIOSH, 2015d) regarding the 1973 tritium model. 

NIOSH (2015c) presents NIOSH’s approach to DR for tritium exposures in the three parts of 

appendix 1, as follows: 

• Part I, “Analysis of Rocky Flats Plant Tritium Exposures for 1959–1973,” by 

J. S. Bogard, Oak Ridge Associated Universities Team (ORAUT) 

• Part II, “Rocky Flats Tritium Dose Assignment for 1973 and Later,” by E. M. Brackett, 

ORAUT, and attachment A, “Tritiated Water Models,” by Thomas LaBone, Nancy 

Chalmers, and E. M. Brackett, ORAUT 

• Part III, “Example RFP Tritium Dose Reconstruction,” by Mutty Sharfi, ORAUT 

SC&A and the work group found no issues with NIOSH’s approach for dose reconstructing 

tritium exposures for 1959–1973, wherein a pre-1973 dose was assigned using the bounding 

estimate of 37.5 millirem (mrem)/year (0.15 mrem/day during 250 days a year) of potential 

exposure prior to 1973. That approach was accepted at the work group’s July 2015 meeting. 

For the time periods 1973 and post-1973, SC&A reviewed NIOSH’s two 2015 white papers: 

“Follow-up Efforts on SEC-00192, Rocky Flats Plant Tritium Issues,” revisions 2 and 3 

(NIOSH, 2015c, 2015d). SC&A provided its responses in its July 13, 2015, paper, “Review and 

Commentary on the NIOSH White Paper, ‘Follow-up Efforts on SEC-00192, Rocky Flats Plant 

Tritium Issues,’ Revision 2” (SC&A, 2015d), and in its June 6, 2016, response to NIOSH’s 

revision 3 (SC&A, 2016). 

For 1973 tritium exposures, SC&A reviewed alternative dose estimation models for comparison 

and found the resulting differences to be minor. For example, if NIOSH had used the new ICRP 

model2

 or the model published by David Taylor (2003), the dose would be a little higher, i.e., 

40 mrem to 50 mrem higher, depending on which dosimetric model is applied. As this dose is 

just assigned to one year, 1973, for unmonitored workers, the difference in dose estimated will 

not be substantive and will have negligible influence on the Interactive RadioEpidemiological 

Program (IREP) probability of causation calculations (SC&A, 2016). 

2 This is the International Commission on Radiation Protection (ICRP) retention and dosimetric model for tritiated 

water contained in ICRP Publication 78 (1997). 

For post-1973 exposures, NIOSH concluded that the 95th percentile of the co-exposure study for 

1974–1975 yielded doses much less than 1 mrem for everyone. SC&A supported NIOSH’s 

conclusion that no workers experienced undetected exposures to tritium following the April 1973 

incident that could have resulted in doses in excess of 1 mrem/year. Using a worst-case scenario, 

for 1974 the air sample results prior to August 30 had an average of 5,343 plus or minus 
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4,518 picocuries per cubic meter (pCi/m3) (NIOSH, 2015d, p. 16). This gives a 95th percentile of 

about 15,000 pCi/m3

, which, assuming a normal distribution, comes to about 2.4 mrem/year. 

NIOSH assumed zero doses for 1974–1975 based on coworker urine samples and the 95th 

percentile. SC&A concluded that the addition of a dose of 2.4 mrem for 1974 does not make a 

difference.

SC&A agrees with NIOSH’s conclusion that, for all time periods in question at RFP, NIOSH can 

reconstruct tritium doses with sufficient accuracy. This assessment and conclusion are 

adequately addressed in revision 04 of ORAUT-TKBS-0011-5. 

6.9 Summary and conclusions for TBD-5 

For TBD-5, SC&A’s original site profile review (2005) had three findings and one observation. 

Later work group proceedings had identified additional concerns for internal exposures related to 

the CML, neptunium, Mg-Th, and tritium. For these later concerns, SC&A addressed and 

resolved each of them during work group deliberations and finds that they are adequately 

incorporated into TBD-5 as appendices. 

For finding 1 of its 2005 review (“suggested use of urine bioassay MDA values for plutonium 

and americium appear low”), SC&A now finds that while the urinalysis MDA values provided 

for plutonium and americium for the original and most recent revised TBDs are the same, they 

compare favorably with those of other DOE facilities (e.g., LANL, Hanford, and ORNL), and 

MDA values are provided for conservative conditions (95th percentile). On that basis, SC&A 

recommends closure of this finding. 

For finding 2 (“TBD lacks definitive direction in some instances”), SC&A performed a 

comprehensive review of the various issues upon which this finding was based (e.g., data 

completeness, particle size, type S solubility) and found that all of the identified issues were 

addressed and resolved in TBD-5, revision 04 (NIOSH, 2020c), with one suggested clarification 

needed in table B-11, page 104, which apparently lacks units for the MDA values, which appear 

to be in nanocuries. 

For finding 7 (“TBD does not consider potential contribution of ingestion pathway”), SC&A 

continues to find a lack of clarity about how ingestion intakes would be handled by dose 

reconstructors. TBD-5, revision 04 (NIOSH, 2020c), only refers to ORAUT-OTIB-0060, 

revision 02 (NIOSH, 2018b), on page 22 in reference to selecting solubility type. ORAUTOTIB-0060, revision 02, addresses ingestion intakes on pages 16 and 38, all of which refer to 

OCAS-TIB-009, revision 0 (NIOSH, 2004f). For clarity, SC&A believes that TBD-5 should 

include recommendations for ingestion intakes or direct reference to the appropriate ingestion 

intake-related document. Although SC&A understands that this issue has been resolved in 

practice, ingestion intakes should be addressed by specific guidance in TBD-5 with reference to 

OCAS-TIB-009. Therefore, SC&A recommends this issue remain open until appropriate 

revisions are made in TBD-5. 

For observation 4 (“with an appropriate wound dose model not available, the cited approach for 

estimating wound-related uptakes in the internal dose TBD is claimant favorable for relevant 

types of cancer, except for lymph nodes and skin cancers”), SC&A found that TBD-5, 

revision 04, adequately addressed a concern that an available proposed wound dose model may 
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be more claimant favorable by including references to Guilmette and Durbin (2003) and other 

assessments for purposes of guiding dose reconstructors. SC&A recommends that this 

observation to be resolved. 

SC&A performed a general review of TBD-5, revision 04, and did not identify any additional 

issues. 

7 Review of TBD-6 Occupational External Dose, ORAUT-TKBS-0011-6, 

Rev. 03

The following sections summarize SC&A’s evaluation of the revised TBD-6 for occupational 

external dose, ORAUT-TKBS-0011-6, revision 03 (NIOSH, 2019b), in view of previously

identified issues and a general review of the document. 

7.1 Previously identified issues

In its 2005 site profile review, SC&A (2005) identified several potential external DR issues in 

ORAUT-TKBS-0011-6, revision 00 (NIOSH, 2004d), for RFP energy employees. SC&A 

reviewed revision 03 of TBD-6 (NIOSH, 2019b) to determine if the potential DR issues had been 

addressed and resolved. The following documents are relevant to this review: 

• ORAUT-TKBS-0011-6, revision 00 (NIOSH, 2004d) 

• SCA-TR-TASK1-0008, revision 0 (SC&A, 2005) 

• ORAUT-TKBS-0011-6, revision 03 (NIOSH, 2019b) 

The potential DR issues that needed further consideration identified in SC&A’s 2005 report were 

as follows (SC&A, 2005, pp. 69–82; relevant section numbers are in parentheses at the end of 

each list item):

• Issue 5: External dose calculation and methodologies (section 5.5) 

• Issue 6: Neutron dosimetry and exposures (section 5.6) 

• Issue 7: Other external dosimetry issues (section 5.7) 

SC&A (2005) presented these three major issues and their subtopics in narrative form in the 

sections given in the preceding list, as opposed to developing a topic followed by a concluding 

finding (or observation), as is presently done in SC&A’s reviews. Therefore, this report 

summarizes the important points to be addressed from the SC&A (2005) sections 5.5–5.7 issues 

and their subtopics. 

The following is SC&A’s evaluation of the status of these three major issues in view of the 

information provided in TBD-6, revision 03 (NIOSH, 2019b), and in documents, procedures, and 

accepted practices that have been developed since SC&A’s (2005) review of TBD-6, revision 00. 

7.1.1 SC&A (2005) section 5.5 – Issue 5: External dose calculations and methodologies

In this section, SC&A described concerns about a number of areas. The following subsections 

address each of these concerns. 
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7.1.1.1 SC&A (2005) section 5.5.1 – areas of concern in records and dose reconstruction

Issue: SC&A (2005) observed a number of areas of concern when evaluating the information for 

DR provided in the TBD. There appeared to be inconsistencies or gaps in some of the 

information. Some of these areas of concern were as follows: 

• SC&A (2005) section 5.5.1.1 – Dose reconstruction from badge readings versus 

historical documents

SC&A finds that revision 03 of TBD-6 adequately addressed this area of concern in 

table 6-3 (p. 30) and on pages 40–42. Equations for shallow and deep doses are provided 

for various time periods. SC&A recommends closure of this issue. 

• SC&A (2005) 5.5.1.2 – Incomplete or inconsistent dose information 

SC&A finds that revision 03 of TBD-6 adequately addressed this area of concern about 

the interpretation of the external dosimetry records in section 6.3 on pages 14–19 and 

table 6-2 (p. 20). SC&A recommends closure of this issue. 

7.1.1.2 SC&A (2005) section 5.5.2 – job exposure matrix study

Issue: SC&A noted that NIOSH agrees that the DOE-funded job exposure matrix study 

(Ruttenber et al., 2003) is important to characterizing worker exposures at RFP and will be 

especially critical to external DR, where coworker assignments will benefit from job-specific 

exposure data.

SC&A finds that revision 03 of TBD-6 addressed this issue in section 6.3.5.3. NIOSH (2019b, 

p. 19) states:

NIOSH reviewed the data available from this project and concluded that the 

material is valuable for epidemiological studies but is of limited utility for NIOSH 

dose reconstruction. 

Therefore, the job exposure matrix study has not been found useful for DR purposes. SC&A 

recommends closure of this issue. 

7.1.1.3 SC&A (2005) section 5.5.3 – below 10 mrem dose reported as zero 

Issue: TBD-6, revision 00 (NIOSH, 2004d), stated on page 20 that any dose below 10 mrem was 

reported as zero dose at RFP in 1993. The DR should take this into account when assigning dose 

and base it on the appropriate LOD at the time.

SC&A finds that revision 03 of TBD-6 adequately addressed this area of concern about missed 

dose and the LOD in section 6.6.3 (pp. 42–43) and table 6-11. SC&A recommends closure of 

this issue. 

7.1.1.4 SC&A (2005) section 5.5.4 – badges only calibrated for one work location 

Issue: Individuals sometimes worked on temporary or overtime assignments in other facilities (or 

at other jobs) in addition to the assignment for which their badge was calibrated. This could lead 

to an underestimate of the worker’s dose if this was a common practice. 
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SC&A finds that revision 03 of TBD-6 adequately addressed this area of concern about photon 

energy groups in section 6.6.1 (pp. 39–42) and table 6-9. SC&A recommends closure of this 

issue.

7.1.1.5 SC&A (2005) section 5.5.5 – exposure geometry 

Issue: In the DR process, the assignment of isotropic and rotational instead of anterior-posterior

geometry may not reflect the true radiation dose to some workers.

SC&A finds that revision 03 of TBD-6 adequately addressed this area of concern about exposure 

geometry in section 6.5.4 (pp. 31–33) and tables 6-5 and 6-6. SC&A recommends closure of this 

issue.

7.1.1.6 SC&A (2005) section 5.5.6 – angular dependence for beta/gamma, NTA film, and 

TLDs 

Issue: In TBD-6, revision 00, the issue of angular dependence for different types of radiation and 

different dosimetry systems used through the years is not sufficiently addressed, and at least 

some general guidelines for consistency would be helpful.

SC&A finds that revision 03 of TBD-6 adequately addressed this area of concern in 

section 6.6.4.1 (p. 44) for photons and section 6.7.4.1 (p. 53) for neutrons. NIOSH found that the 

angular dependence is approximately 1.0 for photon dosimeters, NTA film, and 

thermoluminescent dosimeters (TLDs). The small variability does not warrant a correction factor 

for DR purposes and is sometimes claimant favorable for some dosimeters. SC&A recommends 

closure of this issue.

7.1.1.7 SC&A (2005) section 5.5.7 – use of dosimeters under lead aprons

Issue: In some buildings and jobs, workers wore their dosimeters outside their protective lead 

aprons where the dosimeter would register the exposure dose, but in other buildings and jobs,

workers wore their dosimeters under their protective lead aprons where the dosimeters would not 

register the total dose to the head, neck, and lower parts of the body.

SC&A finds that revision 03 of TBD-6 adequately addressed this area of concern in section 6.5.5 

(pp. 33–34), concerning the use of lead aprons, and in the recommendations summarized in 

table 6-7. SC&A recommends closure of this issue.

7.1.1.8 SC&A (2005) section 5.5.8 – location of dosimeters when working around 

gloveports/boxes

Issue: The location of dosimeters when working around gloveports/boxes was not identified or 

addressed in the TBD and should be investigated because of the possibility of unmonitored doses 

to gloveport/box workers, especially over extended periods.

SC&A finds that revision 03 of TBD-6 adequately addressed this area of concern about glovebox 

work in section 6.5.4 (p. 31), which refers the dose reconstructor to DCAS-TIB-0010, 

revision 04, “Best Estimate External Dose Reconstruction for Glovebox Workers” (NIOSH, 

2011). SC&A recommends closure of this issue.
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7.1.1.9 SC&A (2005) section 5.5.9 – elevated ambient levels of external radiation affect 

net dose 

Issue: Elevated ambient levels of external radiation may have occurred at RFP. This could have 

occurred at locations where radioactive materials were handled, transported, piped, stored, or 

dispersed into the environment. Therefore, there is a need to account for ambient levels of 

external radiation as occupational exposures in situations where the control dosimeters were 

stored in locations with ambient levels of external radiation.

SC&A finds that revision 03 of TBD-6 adequately addressed this area of concern about the 

potential elevated background at the RFP in section 6.5.7 (pp. 35–36). Section 6.5.7 refers the 

dose reconstructor to ORAUT-PROC-0060, revision 01, “Occupational Onsite Ambient Dose 

Reconstruction for DOE Sites” (NIOSH, 2006), which is in the process of being replaced by 

ORAUT-OTIB-0088, revision 02, “External Dose Reconstruction” (NIOSH, 2021). SC&A 

recommends closure of this issue.

7.1.2 SC&A (2005) section 5.6 – Issue 6: Neutron dosimetry and exposures

In this section, SC&A described concerns about a number of areas. The following subsections 

address each of these concerns.

7.1.2.1 SC&A (2005) section 5.6.1 – the likelihood of unmeasured neutron exposures 

Issue: Documentation exists that establishes the considerable uncertainties and primitive nature 

of neutron measurements in the early years, as evidenced by the incomplete criticality safety 

program of the era.

SC&A finds that revision 03 of TBD-6 adequately addressed this area of concern in 

section 6.7.3.3 (pp. 51–53), using the NDRP and neutron-to-photon ratios in tables 6-20 and 6-21

(p. 54). If available, information in an energy employee’s files can be used for neutron DR; 

however, there are insufficient data to create a co-exposure model for neutron exposures prior to 

1967 according to the results of RFP SEC-00030 (NIOSH, 2007c). SC&A recommends closure

of this issue.

7.1.2.2 SC&A (2005) section 5.6.2 – use of neutron track plates and uncertainties in 

dosimetry, 1951–1957

Issue: In view of the uncertainties in the neutron dosimetry processes during the time period 

1951 through 1957, it is not apparent that the recorded neutron dose is correct or claimant 

favorable.

SC&A finds that revision 03 of TBD-6 adequately addressed this area of concern in 

section 6.7.3.3 (pp. 51–53) using the NDRP. If available, information in an energy employee’s 

files can be used for neutron DR; however, there are insufficient data to create a co-exposure 

model for neutron exposures prior to 1967 according to RFP SEC-00030 (NIOSH, 2007c). 

SC&A recommends closure of this issue.
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7.1.2.3 SC&A (2005) section 5.6.3 – NTA neutron energy threshold may lead to missed 

dose in RFP records 

Issue: The neutron dose sections in the TBD need to be revised in view of the NDRP report (Falk 

et al., 2005), and similar analysis is needed to include other non-plutonium workers exposed to 

neutrons.

SC&A finds that revision 03 of TBD-6 adequately addressed this area of concern in 

section 6.7.3.3 (pp. 51–53), using the NDRP and neutron-to-photon ratios in tables 6-20 and 6-21

(p. 54). If available, information in an energy employee’s files can be used for neutron DR; 

however, there are insufficient data to assign other neutron doses or to create a co-exposure 

model for neutron exposures prior to 1967 according to the results of RFP SEC-00030 (NIOSH, 

2007c). SC&A recommends closure of this issue.

7.1.2.4 SC&A (2005) section 5.6.4 – NDRP report lacks important dose reconstruction 

information 

Issue: There are limitations to applying the NDRP report (Falk et al., 2005), as follows:

• NDRP does not cover non-plutonium workers (SC&A, 2005, section 5.6.4.1)

SC&A finds that revision 03 of TBD-6 adequately addressed this area of concern in 

section 6.7.3.4 (p. 53) through the use of neutron-to-photon ratios during DR for any 

applicable RFP energy employee with dose information from any facility, and the use of 

co-exposure data in tables C-5 and C-8 for uranium workers. SC&A recommends closure

of this issue.

• Use of neutron/photon ratios and film/TLD comparisons needed (SC&A, 2005, 

section 5.6.4.2)

SC&A finds that revision 03 of TBD-6 adequately addressed this area of concern by the 

use of the NDRP and neutron-to-photon ratios provided in tables 6-20 and 6-21, and the 

fact that there are insufficient data to assign other neutron doses or to create a 

co-exposure model for neutron exposures prior to 1967 according to the results of RFP 

SEC-00030 (NIOSH, 2007c). SC&A recommends closure of this issue.

7.1.2.5 SC&A (2005) section 5.6.5 – neutron dose multiplication factor 

Issue: Information concerning the use of the neutron dose missed by NTA film needs to be 

corrected.

SC&A finds that revision 03 of TBD-6 adequately addressed this area of concern in section 6.7.3 

(pp. 49–53) per the analysis in the NDRP. SC&A recommends closure of this issue.

7.1.3 SC&A (2005) section 5.7 – issue 7: Other external dosimetry issues

In this section, SC&A described concerns about a number of areas. The following subsections 

address each of these concerns.
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7.1.3.1 SC&A (2005) section 5.7.1 – unmonitored individuals 

Issue: There is concern that some workers, especially during the early years, may not have been 

recognized as having the potential to receive radiation doses from their work at RFP.

SC&A finds that revision 03 of TBD-6 adequately addressed this area of concern in section 6.9 

(p. 62) concerning unmonitored individuals, and in the co-exposure data in attachment C 

(pp. 94–109). SC&A recommends closure of this issue.

7.1.3.2 SC&A (2005) section 5.7.2 – photon and beta dose determination

SC&A (2005) described several areas of concern in this section:

• Photons with E > 250 keV (SC&A, 2005, section 5.7.2.1)

SC&A finds that revision 03 of TBD-6 adequately addressed this area of concern in 

tables 6-8, and 6-9 (pp. 39–40) with default photon energy ranges. SC&A recommends 

closure of this issue.

• Use of VARSKIN software (SC&A, 2005, section 5.7.2.2)

SC&A finds that revision 03 of TBD-6 adequately addressed this area of concern in 

table 6-28 (p. 61), which includes protactinium-234 metastable, and through the use of 

VARSKIN Mod 3 instead of the previous version that used Mod 2 for the applicable 

radionuclides in table 6-28. SC&A recommends closure of this issue.

7.1.3.3 SC&A (2005) section 5.7.3 – extremity dose 

SC&A (2005) described several areas of concern in this section:

• Use of NTA film in wrist badges (SC&A, 2005, section 5.7.3.1)

SC&A finds that it appears that NTA film was not used in extremity dosimetry; neutron 

monitoring of extremities was initiated in 1971 (page 62 of revision 03 of TBD-6). 

According to the results of SEC-00030, neutron dose cannot be reconstructed prior to 

1967 (NIOSH, 2007c). Neutron dose can be reconstructed if records are available per the 

NDRP, according to pages 51–53 of revision 03 of TBD-6. SC&A recommends closure

of this issue.

• Extremity dose assumed to be equal to whole-body dose (SC&A, 2005, 

section 5.7.3.2)

SC&A finds that section 6.10 (p. 62) of revision 03 of TBD-6 addresses extremity 

dosimetry. RFP used film dosimetry for extremity dose measurement during 1951–1970, 

then changed to TLDs in 1971. RFP dosimetrists applied hand-to-wrist ratios ranging 

from 1.5 to 3 as per work location (p. 62). Additionally, page 31 of TBD-6, revision 03,

recommends use of the glovebox factors in DCAS-TIB-0010 (NIOSH, 2011). SC&A 

recommends closure of this issue.
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• Valid hand-to-wrist ratios (SC&A, 2005, section 5.7.3.3)

SC&A finds that section 6.10 (p. 62) of revision 03 of TBD-6 addresses extremity 

dosimetry. RFP used film dosimetry for extremity dose measurement during 1951–1970, 

then changed to TLDs in 1971. RFP dosimetrists applied hand-to-wrist ratios ranging 

from 1.5 to 3 as per work location (p. 62). SC&A recommends closure of this issue.

7.1.3.4 SC&A (2005) section 5.7.4 – industrial x-ray units and neutron generators

Issue: The number of units, energies, periods of operations, operating procedures, etc., needs to 

be determined to assess the potential radiation exposures, and if radiation doses were underrecorded or missed.

SC&A did not find that revision 03 of TBD-6 specifically addressed industrial x-ray units and 

neutron generators (maximum energy of 14 mega-electron volts (MeV)). However, the photon 

and neutron energy intervals that TBD-6 recommends to use in DR include energies likely to be 

encountered from these radiation sources, which would be required to be shielded for industrial 

use. A default photon energy interval of >250 keV is listed in table 6-8 (p. 39) and table 6-9 

(p. 40), and default neutron energy ranges include 2.0–20 MeV neutrons in table 6-16 (p. 48). 

SC&A recommends closure of this issue.

7.1.3.5 SC&A (2005) section 5.7.5 – decontamination and decommissioning activities not 

addressed

Issue: D&D activities present nonroutine situations and unique external and internal monitoring 

requirements. These issues were not mentioned or addressed in the TBD.

SC&A finds that revision 03 of TBD-6 addressed D&D workers on page 92 of attachment B.

Tables 6-2 (p. 29), 6-5 (p. 33), and 6-6 (p. 33) include D&D workers in their recommendations. 

SC&A recommends closure of this issue.

7.2 Resolution of findings

SC&A’s (2005) site profile review summarized these issues in findings 3, 4, 6, 10, and 11 of the 

“Executive Summary” (pp. 15–18). These five findings were as follows:

• Finding 3: Interpretation of NTA film data for workers who were not included in NDRP

reevaluation is not evident; guidance on use of neutron/photon ratios not available.

• Finding 4: Unclear treatment in TBD of personal dosimeter placement and angular

dependence.

• Finding 6: The site profile, while incorporating methodologies for assignment of missed

dose, has not adequately bound exposure conditions, compensated for calibration errors

and technology deficiencies, and addressed possible data integrity issues, all of which 

may contribute to missed dose.

• Finding 10: Hand and wrist doses are not adequately addressed in the external dosimetry

TBD.
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• Finding 11: The TBDs (NIOSH, 2004d, 2004g) do not address the potentially significant 

doses from industrial x-ray and neutron generators for R&D and nondestructive work 

done at RFP. 

As summarized in section 7.1 of this report, SC&A has reviewed the issues covered by these five 

findings and found that they have been addressed and resolved. SC&A recommends closure of 

findings 3, 4, 6, 10, and 11. 

7.3 General review of ORAUT-TKBS-0011-6, revision 03

SC&A had not performed a general review of the RFP occupational external dose TBD since 

2005. Several revisions of TBD-6, new and revised OTIBs applicable to RFP DR, and accepted 

practices have been developed since revision 00 was issued in 2004 (NIOSH, 2004d). Therefore, 

SC&A reviewed TBD-6, revision 03 (NIOSH, 2019b), to determine its technical accuracy and 

applicability to the RFP DR process. The following subsections summarize the results of 

SC&A’s review.

7.3.1 Sections added to revision 03 of TBD-6 

TBD-6 has been progressively updated to address RFP issues that have arisen since revision 00 

was issued (NIOSH, 2004d). NIOSH added the following sections to accomplish these updates 

in order to address external DR issues: 

• 6.1.3, “Special Exposure Cohort” 

• 6.3.2.3, “Shallow Dose Minus Neutron Dose Is Less than Photon Dose” 

• 6.3.4, “Interpretation of Dosimetry Data” 

• 6.4.5, “Recorded Dose Practices” 

• 6.5.5, “Lead Aprons” 

• 6.5.6, “Recycled Uranium” 

• 6.5.7, “Potential Elevated Background Subtraction” 

• 6.5.8, “Badge Reading Policy, 1969 to 1970” 

• 6.5.9, “Gammacell 220 Cobalt-60 Irradiator” 

• 6.6.1.2, “Dosimeter-Indicated Photon Energy” 

– 6.6.1.2.1, “Pre-1960” 

– 6.6.1.2.2, “1960 to 1970” 

– 6.6.1.2.3, “1970 to Present” 

• 6.7.3.4, “Default Neutron-to-Gamma Ratio” 

• 6.11, “Attributions and Annotations” 

Additionally, NIOSH has expanded sections to further address external dose issues or address 

issues that had been identified since revision 00 was issued (NIOSH, 2004d). For example, 

section 6.7.3.3 addressing the NDRP contains addition information concerning neutron dose 

assignments. 
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7.3.2 TBD-6 section 6.5.9 – Gammacell 220 cobalt-60 irradiator 

NIOSH added section 6.5.9 concerning Co-60 sources to revision 03 of TBD-6. There were two 

Co-60 sources of exposure in Building 779 at RFP: (1) a Gammacell 220 irradiator in room 218 

and (2) a Co-60 orphan source found in room 125. 

7.3.2.1 Gammacell 220 irradiator

The Gammacell 220 irradiator was installed in RFP Building 779 in the late 1960s and removed 

in October 1999. It contained 21,900 curies (Ci) of Co-60 as of April 1971 (Rocky Mountain 

Remediation Services, 1999, PDF p. 3). The Co-60 sources were sealed and not removable from 

the unit. There were concerns that the unit may not have been properly monitored to prevent 

exposure to personnel. 

NIOSH addressed this concern in section 6.5.9 of ORAUT-TKBS-0011-6, revision 03 (NIOSH, 

2019b, p. 38), as follows: 

No quantitative leak test results are available during or before 1989. However, a 

1987 report indicates that of 21 sources (22,249 Ci total activity) surveyed there 

were no leaking 60Co sealed sources . . . . Therefore, it is assumed that source 

integrity verification requirements existed sometime before 1989, and that some 

leak test measurements were conducted. In addition, unmonitored personnel 

exposure from leaking 60Co sources (including the Gammacell 220) are unlikely. 

If the Gammacell 220 had leaked, the resulting contamination would have been 

detected in later surveys, some documentation of which has been captured. 

Therefore, no additional exposures need to be assessed associated with the 

Gammacell 220. 

The issue of the Gammacell 220 irradiator source has been addressed, resolved, and previously 

closed.

7.3.2.2 Orphan cobalt-60 source

An orphan Co-60 sealed source was found in a cabinet in room 125 of Building 779 in 1998. 

Although the source had no marking or other labels, it appeared to be a check source and could 

not have been associated with the Gammacell 220 in room 218. The orphan source was disposed 

in November 1998 (RFETS, 1998, PDF pp. 2–4).

At the RFP work group meeting of October 28, 2015 (ABRWH, 2015, p. 31), the work group 

discussed and closed the Co-60 issues. SC&A finds that the concerns about Co-60 sources in 

Building 779 at RFP have been addressed, resolved, and closed by the work group. 

7.3.3 Tables added to revision 03 of TBD-6 

NIOSH added the following tables to revision 03 of TBD-6: 

• Table 6-1, “Interpretation of reported data” 

• Table 6-3, “Summary of historical recorded dose practices” 
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• Table 6-7, “Bias correction factors for application to dose received while wearing a lead 

apron”

• Table 6-20, “RFP lognormal neutron-to-photon ratio values, 1970 to 1976”

• Table 6-21, “ORAU Team-developed neutron-to-gamma ratios”

• Tables in attachment C, “External Coworker Dosimetry Data for Rocky Flats Plant”:

– Table C-1, “Missed external doses”

– Table C-2, “Lognormal neutron-to-photon ratio values, 1970 to 1976”

– Table C-3, “Annual external coworker doses for plutonium workers, 1952 to 1970”

– Table C-4, “Annual external coworker doses for plutonium workers, 1971 to 2005”

– Table C-5, “Annual external coworker doses for uranium workers, 1952 to 2005”

– Table C-6, “Annual external coworker doses for plutonium workers, 1952 to 1970, 

modified in accordance with ORAUT-OTIB-0052”

– Table C-7, “Annual external coworker doses for plutonium workers, 1971 to 2005,

modified in accordance with ORAUT-OTIB-0052”

– Table C-8, “Annual external coworker doses for uranium workers, 1952 to 2005, 

modified in accordance with ORAUT-OTIB-0052”

NIOSH discusses the origin and application of the photon, neutron, and nonpenetrating dose 

values in the tables in attachment C on pages 94–100 of TBD-6, revision 03. The information 

and data in the tables in attachment C were incorporated from the NDRP analysis and former 

technical information bulletins that have been previously reviewed by the RFP work group, 

NIOSH, and SC&A. 

7.3.4 Changes in tables from revision 00 to revision 03

SC&A reviewed the information and dose values recommended in the tables in revision 03 of 

TBD-6 and found that they were correct and in agreement with the previous data in the 

respective tables in revision 00 of TBD-6, except for the following items.

7.3.4.1 Default neutron energy distribution

The values in the third column of table 6-16 (p. 48) of revision 03 of TBD-6 (reproduced here as 

table 1) are all less than those in the third column of table 6-14 (p. 31) of revision 00 of TBD-6

(reproduced here as table 2). This results in the dose multiplier values being corresponding less 

in the fourth column; therefore, slightly less neutron dose would be assigned using the values in 

table 6-16 of revision 03 compared to using the values in table 6-14 of revision 00 of TBD-6.
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Table 1. TBD-6, rev. 03, table 6-16, “Default neutron energy distribution” 

Neutron energy 

intervals

Fraction of dose 

(NCRP 38)

Dose multiplier 

(ICRP 60)

Dose 

multipliera

<10 keV 0.035 2.13 0.0755

10 - 100 keV 0.017 1.86 0.0309

0.1 - 2.0 MeV 0.687 1.91 1.31

2.0 - 20.0 MeV 0.261 1.32 0.345

>20 MeV 0 None None

a Multiply the reported dose by these factors to determine the ICRP 60 neutron dose

for each neutron energy interval.

Source: Reproduced from NIOSH (2019b), p. 48. 

Table 2. TBD-6, rev. 00, table 6-14, “Default neutron energy distribution” 

Neutron energy 

intervals

Fraction of dose 

(NCRP 38)

Dose multiplier 

(ICRP 60)

Dose 

multipliera

<10 keV 0.035 2.40 0.0851

10 - 100 keV 0.017 2.06 0.0342

0.1 - 2.0 MeV 0.687 1.98 1.36

2.0 - 20.0 MeV 0.261 2.50 0.654

>20 MeV 0.00 -- 0.00

a Multiply the reported dose by these factors to determine the ICRP 60 neutron dose

for each neutron energy interval

Source: Reproduced from NIOSH (2004d), p. 31.

Observation 1: Different neutron dose multiplier factors need clarification

The reason for the change in neutron dose multiplier factors listed in table 6-16 of revision 03 

compared to table 6-14 of revision 00 needs clarification. 

7.3.4.2 Tables 6-18 and 6-19 of revision 03

In table 6-18 (p. 50) of revision 03, the fourth column lists a LOD value of 226 mrem for 1962 

and 1963. However, using the formula in column two of table 6-18 and a background blank 

value of 16 tracks per 10 square millimeters, the correct value would appear to be 369 mrem, 

which would also apply to the second column of table 6-19 (p. 51) for 1962 and 1963. 

Observation 2: LOD values for 1962 and 1963 need clarification

The reason for recommending 226 mrem instead of the calculated value of 369 mrem in 

tables 6-18 and 6-19 needs clarification.

7.3.4.3 LOD values for 2004 and 2005

LOD values for photons in table 6-11 (p. 43), for neutrons in table 6-19 (p. 51), and for betas in 

table 6-23 (p. 58) of TBD-6, revision 03, are recommended for the years 2004 and 2005, which 

is an update from the corresponding tables in revision 00 of TBD-6. While the recommended 

LOD values are reasonable, they are an addition to the recommended values for 2003 as listed in 

revision 00. Therefore, references or discussion concerning where the 2004 and 2005 LODs were 

obtained are needed.
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Observation 3: References for LOD values for 2004 and 2005 are needed

References for recommending photon, neutron, and beta LOD values for 2004 and 2005 are 

needed.

7.3.5 Missing or incorrect information

SC&A found that the following references were used in the text but were not listed in the 

reference section on pages 64–69:

• Page 10: Sebelius (2013)

• Page 11: NIOSH (2013)

• Page 94: NIOSH (2006)

SC&A found that the caption for table C-8 given in the list of tables at the bottom of page 93 

should use the phrase “uranium workers” not “plutonium workers,” per the actual caption for 

table C-8 on page 108.

7.4 Summary and conclusions for TBD-6

SC&A summarized the issues previously presented in a narrative form in SC&A’s (2005) review 

of TBD-6, revision 00 (NIOSH, 2004d), to determine if the issues were addressed in TBD-6, 

revision 03 (NIOSH, 2019b), other external dose-related documents, or currently accepted 

practices. SC&A found that the three previously identified major issues (external dose 

calculations and methods, neutron dosimetry and exposures, and other potential exposure 

concerns) and their associated subtopics have been addressed and resolved and, therefore,

recommends closure of findings 3, 4, 6, 10, and 11 and all related issues in these findings. The 

issues of the Gammacell 220 irradiator and Co-60 orphan source had been addressed, resolved, 

and previously closed.

SC&A performed a general review of TBD-6, revision 03, and did not identify any findings but 

did have three observations concerning clarifications of changes, or additions, made in the tables. 

SC&A’s review of TBD-6, revision 03, indicated that NIOSH used the information available to 

provide reasonable occupational external DR considering some of the limited information and 

data available in the early years, especially for neutron doses. 

SC&A did note (1) that several references used in the text were not listed in the references 

section, and (2) the incorrect use of “plutonium” instead of “uranium” in the appendix C list of 

tables entry for table C-8 on page 93.

8 Overall Conclusions

SC&A reviewed five RFP TBDs that have been revised as of January 2021 to determine if 

previous issues identified by its original 2005 site profile review were resolved and addressed by 

NIOSH. SC&A also performed a general review of these documents. 

SC&A found that for TBD-2, all previous issues have been addressed in revision 02 (NIOSH,

2020a). A general review found this TBD revision to be more comprehensive in scope and depth 

and to include more details on site closure and decommissioning, as well as information about
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specific operations involving recycled uranium and U-233. SC&A recommends closure of 

finding 8 (inadequate information regarding recycled uranium) from its 2005 review, based on 

updated treatment of the issue in the internal dose TBD (TBD-5). However, no such updated 

assessment was noted in TBD-2, and it is recommended that TBD-2 be revised to be consistent 

with TBD-5. SC&A considers all other identified issues resolved.

For TBD-3, SC&A similarly found that all previous issues as expressed in finding 5 (which was 

concerned with radiation exposure from occupationally necessitated medical x-ray) have been 

addressed and resolved in revision 03 of TBD-3 (NIOSH, 2019a) and recommends closure. A 

general review of this most recent revision did not identify any findings, although some incorrect 

tables were listed in the publication record on page 2 of the TBD.

SC&A’s review of TBD-4, revision 03 (NIOSH, 2020b), found that the revised TBD addressed 

and resolved SC&A’s finding 9 from its original 2005 site profile review regarding inadequacies 

in addressing potential environmental exposure from routine and ambient airborne releases and 

resuspension of contaminated soil at RFP. SC&A found that NIOSH (1) has added more specific 

information and guidance about the contribution of resuspension of soil contaminants for 

occupational environmental exposures and (2) provides better justification of its basis in 

available site monitoring data. Therefore, SC&A recommends closure of this finding.

SC&A also found satisfactory the TBD-4, revision 03, treatment of other issues, such as use of 

the RATCHET air dispersion model and consideration of potential environmental DR issues 

stemming from the 1989 FBI investigation.

For TBD-5, SC&A’s original site profile review (2005) had three findings and one observation, 

and later work group proceedings had identified additional concerns for internal exposures 

related to the CML, neptunium, Mg-Th, and tritium. For these later concerns, SC&A, together 

with NIOSH and the work group, addressed and resolved each of them during work group 

deliberations and finds that they are adequately incorporated into TBD-5 as appendices.

For finding 1 of its 2005 review (suggested use of urine bioassay MDA values appears low) and 

finding 2 (TBD lacks definitive direction in some instances), SC&A now finds that NIOSH 

(2020b) has addressed and resolved them in revision 03 and recommends closure.

For finding 7 (TBD does not consider potential contribution of ingestion pathway), SC&A 

continues to find a lack of clarity about how ingestion intakes would be handled by dose 

reconstructors. TBD-5, revision 04 (NIOSH, 2020c), only refers to ORAUT-OTIB-0060, 

revision 02 (NIOSH, 2018b), on page 22 in reference to selecting solubility type. ORAUTOTIB-0060 addresses ingestion intakes on pages 16 and 38, both of which refer to OCAS-TIB009, revision 0 (NIOSH, 2004f). For clarity, SC&A believes that TBD-5 should include 

recommendations for ingestion intakes or direct reference to the appropriate ingestion-intakerelated document. Although SC&A understands that this issue has been resolved in practice, 

ingestion intakes should be addressed by specific guidance in TBD-5 with reference to OCASTIB-009. Therefore, SC&A recommends that this issue remain open until appropriate revisions 

are made in TBD-5.
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Privacy Act 5 U.S.C. § 552a and has been cleared for distribution.

For the one observation by SC&A (2005) regarding additional guidance for wound modeling, 

SC&A finds that additional references are now included, including one recommended in the 

2005 site profile review.

The issue of potential internal exposures from the CML had been addressed, resolved, and 

previously closed.

SC&A reviewed revision 03 of TBD-6 (NIOSH, 2019b), compared it with the issues described in 

its 2005 site profile review, and determined that the previously identified issues in the five

findings (3, 4, 6, 10, and 11) have been addressed and resolved. Therefore, SC&A recommends 

closure of all TBD-6 findings and issues from SC&A (2005). The five findings were as follows:

• Finding 3 was concerned with the interpretation of NTA film data for workers who were 

not included in the NDRP. The revised TBD-6 addressed this finding.

• Finding 4 was concerned with the treatment of personal dosimeter placement and angular 

dependence. The revised TBD-6 addressed this finding by analysis of angular 

dependence of the monitoring devices.

• Finding 6 was concerned with potential calibration errors, technology deficiencies, and 

possible data integrity issues that could have contributed to missed dose. The revised 

TBD-6 addressed these issues.

• Finding 10 was concerned with hand and wrist doses. The revised TBD-6 addressed these 

extremity doses.

• Finding 11 was concerned with the potentially significant doses from industrial x-ray and 

neutron generators for R&D and nondestructive work. The revised TBD-6 addressed 

these issues.

The issue of the Gammacell 220 irradiator and cobalt-60 (Co-60) orphan source was previously

addressed, resolved, and closed.

SC&A’s general review of the TBD found no further issues but did result in three observations: 

1. Use of different neutron dose multiplier factors needs clarification.

2. LOD values for 1962 and 1963 need clarification.

3. References for LOD values for 2004 and 2005 are needed. 

Additionally, several other references need to be added, and the attachment C list of tables on 

page 93 incorrectly substitutes “plutonium” for “uranium” in the table C-8 caption.
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Privacy Act 5 U.S.C. § 552a and has been cleared for distribution. 

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