Report Rev # 0 Report Submittal Date 2-01-2007 

Subject Expert(s): Tim Vitkus, Tim Adler, Ray Clark, Dan Mantooth, Clark Barton, Vernon 

Shockley, Ron Kathren 

Site Expert(s): Jack Buddenbaum 

SEC Petition Evaluation Report 

Petition SEC-00051 

Petition Administrative Summary 

Petition Under Evaluation 

Petition # Petition 

Type 

Petition B 

Qualification Date 

DOE/AWE Facility Name 

SEC-00051 83.13 August 7, 2006 Los Alamos National Laboratory (LANL) 

Petitioner Class Definition 

All workers of LANL working in all Tech Areas from 1943 - 1975. 

Proposed Class Definition 

All employees of the DOE or DOE contractors or subcontractors who were monitored, or should have been 

monitored, for radiological exposures while working in operational Technical Areas with a history of 

radioactive material use at the Los Alamos National Laboratory for an aggregate of at least 250 work days 

during the period from March 15, 1943 through December 31, 1975, or in combination with work days within 

the parameters established for one or more other classes of employees in the SEC. This definition excludes 

TA-1-Z, TA-17, -19, -28, -34, -38, -57, -64, -65, -69, -70, and -74. 

Related Petition Summary Information 

SEC Petition Tracking #(s) Petition Type DOE/AWE Facility Name Petition Status 

None 

Related Evaluation Report Information 

Report Title DOE/AWE Facility Name 

SEC Petition Evaluation Report, SEC-00061 LANL 

ORAU Lead Technical Evaluator: Tim Vitkus ORAU Review Completed By: K. Jessen, D. Stempfley 

Peer Review Completed By: Signature on file 

Gregory V. Macievic 

2/6/07 

Date 

SEC Petition Evaluation Reviewed By: Signature on file 

Jim Neton 

2/6/07 

Date 

SEC Evaluation Approved By: Signature on file 

Larry Elliott 

2/6/07 

Date 

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Evaluation Report Summary: SEC-00051 

Los Alamos National Laboratory (LANL) 

This evaluation report by the National Institute for Occupational Safety and Health (NIOSH) addresses a class 

of employees proposed for addition to the Special Exposure Cohort (SEC) per the Energy Employees 

Occupational Illness Compensation Program Act of 2000, as amended, 42 U.S.C. § 7384 et seq. (EEOICPA) 

and 42 C.F.R. pt. 83, Procedures for Designating Classes of Employees as Members of the Special Exposure 

Cohort under the Energy Employees Occupational Illness Compensation Program Act of 2000. 

Petitioner-Requested Class Definition 

Petition SEC-00051, qualified on August 7, 2006, requested that NIOSH consider the following class: All 

workers of LANL working in all Tech Areas from 1943 - 1975. 

NIOSH-Proposed Class Definition 

Based on its research, NIOSH modified the petitioner-requested class to define a single class of employees for 

which NIOSH cannot estimate radiation doses with sufficient accuracy. The NIOSH-proposed class includes 

all employees of the DOE or DOE contractors or subcontractors who were monitored, or should have been 

monitored, for radiological exposures while working in operational Technical Areas with a history of 

radioactive material use at the Los Alamos National Laboratory for an aggregate of at least 250 work days 

during the period from March 15, 1943 through December 31, 1975, or in combination with work days within 

the parameters established for one or more other classes of employees in the SEC. This definition excludes 

TA-1-Z, TA-17, -19, -28, -34, -38, -57, -64, -65, -69, -70, and -74. The class was modified (see Section 3.0 

below) in order to: (1) specify the date when project staff began work at the site (March 15, 1943); (2) confine 

the class to those Technical Areas that had a history of radioactive material use and were also operational 

during the evaluation period; and (3) explicitly include all personnel who worked for the DOE, DOE 

contractors, or subcontractors (including all former MED/AEC workers) who were monitored or should have 

been monitored for radiological exposure. 

Feasibility of Dose Reconstruction 

Per EEOICPA and 42 C.F.R. § 83.13(c)(1), NIOSH has established that it does not have access to sufficient 

information to: (1) estimate the maximum radiation dose incurred by any member of the class; or (2) estimate 

radiation doses more precisely than a maximum dose estimate. Information available from the site profile and 

additional resources is not sufficient to document or estimate the maximum internal and external potential 

exposure to members of the proposed class under plausible circumstances during the specified period. NIOSH 

will continue its evaluation to determine at what historical point (after the evaluation period addressed herein) 

that available information and data become adequate to: (1) estimate the maximum radiation dose incurred by 

any site worker; or (2) estimate radiation doses more precisely than a maximum dose. 

Health Endangerment Determination 

Per EEOICPA and 42 C.F.R. § 83.13(c)(3), a health endangerment determination is required because NIOSH 

has determined that it does not have sufficient information to estimate long-term doses for the members of the 

proposed class. Evidence indicates that some workers in the proposed class may have accumulated substantial 

chronic exposures through episodic intakes of radionuclides, combined with external exposures to gamma, beta, 

and neutron radiation. Consequently, NIOSH has determined that health was endangered for those workers 

covered by this evaluation who were employed for at least 250 aggregated work days either solely under their 

employment or in combination with work days within the parameters established for other SEC classes 

(excluding aggregate work day requirements). 

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Table of Contents 

Evaluation Report Summary: SEC-00051 Los Alamos National Laboratory (LANL) .......................... 3 

1.0 Purpose and Scope.......................................................................................................................... 3 

2.0 Introduction .................................................................................................................................... 3 

3.0 Petitioner-Requested Class/Basis & NIOSH-Proposed Class/Basis .............................................. 3 

4.0 Data Sources Reviewed by NIOSH................................................................................................ 3 

4.1 Site Profile Technical Basis Documents (TBDs) .................................................................. 3 

4.2 ORAU Technical Information Bulletins (OTIBs) and Procedures ....................................... 3 

4.3 Facility Employees and Experts ............................................................................................ 3
 

4.4 Previous Dose Reconstructions ............................................................................................. 3
 

4.5 NIOSH Site Research Database ............................................................................................ 3 

4.6 Other Technical Sources........................................................................................................ 3 

4.7 Documentation and/or Affidavits Provided by Petitioners ................................................... 3 

5.0 LANL Radiological Operations Relevant to the Proposed Class................................................... 3 

5.1 LANL Plant and Process Descriptions .................................................................................. 3 

5.2 LANL Functional Areas ........................................................................................................ 3 

5.2.1 LANL Weapons Development and Testing .............................................................. 3 

5.2.2 LANL Critical Assemblies, Reactors, and Reactor Development ............................ 3 

5.2.3 LANL Accelerators, X-Ray Equipment, and Radiography Sources ......................... 3 

5.2.4 LANL Biomedical Research ..................................................................................... 3 

5.2.5 LANL Project Sherwood and Fusion Research......................................................... 3 

5.2.6 LANL Waste Treatment and Disposal ...................................................................... 3 

5.2.7 Summary of Key LANL Facilities ............................................................................ 3 

5.3 Radiological Exposure Sources from LANL Operations ...................................................... 3 

5.3.1 Alpha Particle Emissions........................................................................................... 3 

5.3.2 Beta Particle Emissions ............................................................................................. 3 

5.3.3 Neutron Exposures .................................................................................................... 3 

5.3.4 Photon Exposures ...................................................................................................... 3 

5.3.5 Incidents and Accidents............................................................................................. 3 

6.0 Summary of Available Monitoring Data for the Proposed Class ................................................... 3 

6.1 LANL Internal Monitoring Data ........................................................................................... 3 

6.1.1 Air Sampling Data ..................................................................................................... 3 

6.1.2 In Vitro Bioassay Sampling Data .............................................................................. 3 

6.1.3 In Vivo Analytical Data ............................................................................................. 3 

6.2 LANL External Monitoring Data .......................................................................................... 3 

6.3 LANL Air Sampling Data ..................................................................................................... 3 

7.0 Feasibility of Dose Reconstruction for the Proposed Class ........................................................... 3 

7.1 Pedigree of LANL Data......................................................................................................... 3 

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7.1.1 Internal Data Review................................................................................................. 3 

7.1.1.1 In Vitro Monitoring Data............................................................................ 3 

7.1.1.2 In Vivo Monitoring Data............................................................................. 3 

7.1.2 External Data Review................................................................................................ 3 

7.2 Internal Radiation Doses at LANL........................................................................................ 3 

7.2.1 Process-Related Internal Doses at LANL.................................................................. 3 

7.2.1.1 Urinalysis Information and Available Data................................................ 3 

7.2.1.2 Lung Counting Information and Available Data ........................................ 3 

7.2.1.3 Other Types of Bioassay/Workplace Indicators ......................................... 3 

7.2.1.4 Airborne Levels .......................................................................................... 3 

7.2.1.5 Radon.......................................................................................................... 3 

7.2.1.6 Application of Co-Worker Data for Internal Dose Reconstruction............ 3 

7.2.2 Ambient Environmental Internal Radiation Doses at LANL .................................... 3 

7.2.3 Internal Dose Reconstruction .................................................................................... 3 

7.2.4 Internal Dose Reconstruction Feasibility Conclusion ............................................... 3 

7.3 External Radiation Doses at LANL....................................................................................... 3 

7.3.1 Process-Related External Radiation Doses at LANL ................................................ 3 

7.3.1.1 Radiation Exposure Environment............................................................... 3 

7.3.1.2 History of Whole Body External Monitoring............................................. 3 

7.3.1.3 History of Extremity Monitoring................................................................ 3 

7.3.1.4 Neutron Dosimetry Issues and Dose Reconstruction ................................. 3 

7.3.1.5 Dosimetry Records ..................................................................................... 3 

7.3.1.6 Application of Co-Worker Data for External Dose Reconstruction .......... 3 

7.3.2 Ambient Environmental External Radiation Doses at LANL ................................... 3 

7.3.3 LANL Occupational X-Ray Examinations ............................................................... 3 

7.3.4 External Dose Reconstruction ................................................................................... 3 

7.3.4.1 Photon Dose................................................................................................ 3 

7.3.4.2 Electron Dose ............................................................................................. 3 

7.3.4.3 Neutron Dose .............................................................................................. 3 

7.3.4.4 Unmonitored Individuals Working in Production Areas............................ 3 

7.3.4.5 Medical X-ray............................................................................................. 3 

7.3.5 External Dose Reconstruction Feasibility Conclusion .............................................. 3 

7.4 Evaluation of Petition Basis for SEC-00051 ......................................................................... 3 

7.4.1 Evaluation of Major Topics Detailed in Petition SEC-00051 ................................... 3 

7.4.1.1 Insufficient Data ......................................................................................... 3 

7.4.1.2 Records Do Not Exist................................................................................. 3 

7.4.1.3 Lack of Bioassay Data................................................................................ 3 

7.4.3 Evaluation of General Concerns Raised in Petition SEC-00051............................... 3 

7.5 Other Issues Relevant to the Petition Identified During the Evaluation ............................... 3 

7.6 Summary of Feasibility Findings for Petition SEC-00051.................................................... 3 

8.0 Evaluation of Health Endangerment for Petition SEC-00051........................................................ 3 

9.0 NIOSH-Proposed Class for Petition SEC-00051 ........................................................................... 3 

10.0 References ...................................................................................................................................... 3 

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Tables 

4-1: No. of LANL Claims Submitted Under the Dose Reconstruction Rule......................................... 3 

5-1: LANL Technical Areas, Operational Dates, and Radionuclides.................................................... 3 

5-2: Alpha Particle Energies For LANL Alpha-Emitting Radionuclides .............................................. 3 

5-3: Beta Particle Energies For LANL Beta-Emitting Radionuclides ................................................... 3 

5-4: Default Neutron Dose Fractions for LANL Materials ................................................................... 3 

5-5: Default Photon Energies for LANL Operations ............................................................................. 3 

6-1: Summary of Airborne Concentrations from Selected LANL Buildings ........................................ 3 

6-2: LANL Urinalysis Data ................................................................................................................... 3 

6-3: Miscellaneous LANL In Vitro Monitoring Data ............................................................................ 3 

6-4: LANL Chest Monitoring Data........................................................................................................ 3 

6-5: LANL Other In Vivo Monitoring Data........................................................................................... 3 

6-6: LANL Whole Body Monitoring Data ............................................................................................ 3
 

6-7: Summary of Typical Exchange Frequencies for LANL Dosimeters ............................................. 3 

6-8: Annual LANL External Radiation Doses, 1944–1975 ................................................................... 3 

7-1: Tritium VAX Data Files ................................................................................................................. 3 

7-2: Tritium Data Validation Summary ................................................................................................. 3 

7-3: VAX Data Files Containing Uranium-235 Data ............................................................................ 3 

7-4: VAX Data Files Containing Uranium-238 Data ............................................................................ 3 

7-5: Uranium Data Validation Summary ............................................................................................... 3 

7-6: Summary of Errors in Validated Polonium Data ........................................................................... 3 

7-7: LANL Internal Dose Scenarios by Worker Category and ROCs ................................................... 3 

7-8: Summary of LANL Data Deficiencies ........................................................................................... 3 

7-9: LANL Dosimetry Records Chronology ......................................................................................... 3 

7-10: Summary of Feasibility Findings for SEC-00051 .......................................................................... 3 

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SEC Petition Evaluation Report for SEC-00051
 

1.0 Purpose and Scope 

This report evaluates the feasibility of reconstructing doses for all job titles and/or job duties for all 

employees of the DOE or DOE contractors or subcontractors who were monitored, or should have 

been monitored, for radiological exposures while working in operational Technical Areas (TAs) with 

a history of radioactive material use at the Los Alamos National Laboratory for an aggregate of at 

least 250 work days during the period from March 15, 1943 through December 31, 1975, or in 

combination with work days within the parameters established for one or more other classes of 

employees in the SEC. It provides information and analyses germane to considering a petition for 

adding a class of employees to the congressionally-created SEC. 

This report does not make any determinations concerning the feasibility of dose reconstruction that 

necessarily apply to any individual energy employee who might require a dose reconstruction from 

NIOSH. This report also does not contain the final determination as to whether the proposed class 

will be added to the SEC (see Section 2.0). 

This evaluation was conducted in accordance with the requirements of EEOICPA, 42 C.F.R. pt. 83, 

and the guidance contained in the Office of Compensation Analysis and Support’s (OCAS) Internal 

Procedures for the Evaluation of Special Exposure Cohort Petitions, OCAS-PR-004. 

2.0 Introduction 

Both EEOICPA and 42 C.F.R. pt. 83 require NIOSH to evaluate qualified petitions requesting that the 

Department of Health and Human Services (HHS) add a class of employees to the SEC. The 

evaluation is intended to provide a fair, science-based determination of whether it is feasible to 

estimate with sufficient accuracy the radiation doses of the class of employees through NIOSH dose 

reconstructions.1 

42 C.F.R. § 83.13(c)(1) states: Radiation doses can be estimated with sufficient accuracy if NIOSH 

has established that it has access to sufficient information to estimate the maximum radiation dose, 

for every type of cancer for which radiation doses are reconstructed, that could have been incurred in 

plausible circumstances by any member of the class, or if NIOSH has established that it has access to 

sufficient information to estimate the radiation doses of members of the class more precisely than an 

estimate of the maximum radiation dose. 

Under 42 C.F.R. § 83.13(c)(3), if it is not feasible to estimate with sufficient accuracy radiation doses 

for members of the class, NIOSH must also then determine whether or not there is a reasonable 

likelihood that such radiation doses may have endangered the health of members of the class. The 

regulation requires NIOSH to assume that any duration of unprotected exposure may have endangered 

1

 NIOSH dose reconstructions under EEOICPA are performed using the methods promulgated under 42 C.F.R. pt. 82 and 

the detailed implementation guidelines available at http://www.cdc.gov/niosh/ocas. 

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the health of members of a class when it has been established that it is not feasible to reconstruct (the 

incident) exposures for the class and that the class may have been exposed to radiation during a 

discrete incident likely to have involved levels of exposure similarly high to those occurring during 

nuclear criticality incidents. If the feasibility determination of the inability to reconstruct doses from 

an exceptionally high-level exposure has not been established, but NIOSH has determined that it is 

not feasible to reconstruct other (long-term) exposures, then NIOSH is required to specify that health 

was endangered for those workers who were employed for at least 250 aggregated work days within 

the parameters established for the class or in combination with work days within the parameters 

established for other SEC classes (excluding aggregate work day requirements). 

NIOSH is required to document its evaluation in a report, and to do so, relies upon both its own dose 

reconstruction expertise as well as technical support from its contractor, Oak Ridge Associated 

Universities (ORAU). Once completed, NIOSH provides the report to both the petitioner(s) and to the 

Advisory Board on Radiation and Worker Health (Board). The Board will consider the NIOSH 

evaluation report, together with the petition, petitioner(s) comments, and other information the Board 

considers appropriate, in order to make recommendations to the Secretary of HHS on whether or not 

to add one or more classes of employees to the SEC. Once NIOSH has received and considered the 

advice of the Board, the Director of NIOSH will propose a decision on behalf of HHS. The Secretary 

of HHS will make the final decision, taking into account the NIOSH evaluation, the advice of the 

Board, and the proposed decision issued by NIOSH. As part of this decision process, petitioners may 

seek a review of certain types of final decisions issued by the Secretary of HHS.2 

3.0 Petitioner-Requested Class/Basis & NIOSH-Proposed Class/Basis 

Petition SEC-00051, qualified on August 7, 2006, requested that NIOSH consider the following class 

for addition to the SEC: All workers of LANL working in all Tech Areas from 1943 - 1975. 

The petitioner provided information and affidavit statements in support of the petitioner’s belief that 

accurate dose reconstruction over time is impossible for the LANL workers in question. NIOSH 

deemed the following information and affidavit statements sufficient to qualify SEC-00051 for 

evaluation: 

The petition contends that personal exposures in some job categories were unrecorded and 

that accurate data to perform precise dose reconstructions do not exist for some employees. 

The supporting information raises issues associated with unmonitored individuals, lack of 

environmental monitoring prior to 1965, lack of bioassay data, and lack of other relevant 

information needed to document or estimate maximum internal or external exposures, 

particularly during the early years of LANL operations. 

The petitioners provided affidavits from seven individuals who described contamination 

incidents, suspected overexposures, lack of monitoring, and unavailability of records. 

2 See 42 C.F.R. pt. 83 for a full description of the procedures summarized here. Additional internal procedures are 

available at http://www.cdc.gov/niosh/ocas. 

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The information and statements provided by the petitioner qualified the petition for further 

consideration by NIOSH, the Board, and HHS. The details of the petition basis are addressed in 

Section 7.4. 

Based on its research, NIOSH modified the petitioner-requested class to define a single class of 

employees for which NIOSH cannot estimate radiation doses with sufficient accuracy. The NIOSHproposed class includes all employees of the DOE or DOE contractors or subcontractors who were 

monitored, or should have been monitored, for radiological exposures while working in operational 

Technical Areas with a history of radioactive material use at the Los Alamos National Laboratory for 

an aggregate of at least 250 work days during the period from March 15, 1943 through December 31, 

1975, or in combination with work days within the parameters established for one or more other 

classes of employees in the SEC. This definition excludes TA-1-Z, TA-17, -19, -28, -34, -38, -57, ­

64, -65, -69, -70, and -74. The class was modified in order to: (1) specify the date when project staff 

began work at the site (March 15, 1943); (2) confine the class to TAs with a history of radioactive 

material use; and (3) explicitly include all personnel who worked for the DOE, DOE contractors, or 

subcontractors (including all former MED/AEC workers) who were monitored or should have been 

monitored for radiological exposure. 

Table 5-1 summarizes the LANL TAs, key processes, dates of operation, and primary radiation 

sources. Twelve of the listed TAs had no history of radioactive material use or were not operational 

during the evaluation period and were, therefore, excluded from further evaluation in this report: 

TA-1-Z, TA-17, -19, -28, -34, -38, -57, -64, -65, -69, -70, and -74. 

4.0 Data Sources Reviewed by NIOSH 

NIOSH identified and reviewed numerous data sources to determine the availability of information 

relevant to determining the feasibility of dose reconstruction for the class of employees proposed for 

this petition. This included determining the availability of information on personal monitoring, area 

monitoring, industrial processes, and radiation source materials. The following subsections summarize 

the data sources identified and reviewed by NIOSH. 

4.1 Site Profile Technical Basis Documents (TBDs) 

A Site Profile provides specific information concerning the documentation of historical practices at 

the specified site. Dose reconstructors can use the Site Profile to evaluate internal and external 

dosimetry data for monitored and unmonitored workers, and to supplement, or substitute for, 

individual monitoring data. A Site Profile consists of an Introduction and five Technical Basis 

Documents (TBDs) that provide process history information, information on personal and area 

monitoring, radiation source descriptions, and references to primary documents relevant to the 

radiological operations at the site. As part of NIOSH’s evaluation detailed herein, it examined the 

following TBDs for insights into LANL operations or related topics/operations at other sites: 

• Technical Basis Document for Los Alamos National Laboratory – Introduction, 

ORAUT-TKBS-0010-1 Rev. 00; January 25, 2005 

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•	 Technical Basis Document for Los Alamos National Laboratory – Site Description, 

ORAUT-TKBS-0010-2; Rev. 00; May 7, 2004 

•	 Technical Basis Document for Los Alamos National Laboratory – Occupational Medical Dose, 

ORAUT-TKBS-0010-3; Rev. 00; December 29, 2004 

•	 Technical Basis Document for Los Alamos National Laboratory – Occupational Environmental 

Dose, ORAUT-TKBS-0010-4; Rev. 00; October 8, 2004 

•	 Technical Basis Document for Los Alamos National Laboratory – Occupational Internal Dose, 

ORAUT-TKBS-0010-5; Rev. 00; December 21, 2004 

•	 Technical Basis Document for Los Alamos National Laboratory – Occupational External Dose, 

ORAUT-TKBS-0010-6; Rev. 00; May 10, 2005 

4.2 ORAU Technical Information Bulletins (OTIBs) and Procedures 

An ORAU Technical Information Bulletin (OTIB) is a general working document that provides 

guidance for preparing dose reconstructions at particular sites or categories of sites. An ORAU 

Procedure provides specific requirements and guidance regarding EEOICPA project-level activities, 

including preparation of dose reconstructions at particular sites or categories of sites. NIOSH 

reviewed the following OTIBs and procedures as part of its evaluation: 

•	 OTIB: Maximum Internal Dose Estimates for Certain DOE Complex Claims, 

ORAUT-OTIB-0002, Rev. 01 PC-2; May 7, 2004 

•	 OTIB: Internal Dose Overestimates for Facilities With Air Sampling Programs, 

ORAUT-OTIB-0018, Rev. 01; August 9, 2005 

•	 OTIB: Analysis of Coworker Bioassay Data for Internal Dose Assignment, 

ORAUT-OTIB-0019, Rev. 01; October 7, 2005 

•	 OTIB: Assignment of Missed Neutron Doses Based on Dosimeter Records, 

ORAUT-OTIB-0023, Rev. 00; March 7, 2005 

•	 OTIB: Dose Reconstruction Considerations for Recycled Uranium Contaminants, 

ORAUT-OTIB-0053 (draft) 

•	 OTIB: Internal Dosimetry Coworker Data for Los Alamos National Laboratory, 

ORAUT-OTIB-0062 (draft) 

•	 OTIB: Los Alamos National Laboratory Bioassay Data Project, 

ORAUT-OTIB-0063 (draft) 

•	 Generating Summary Statistics for Coworker Bioassay Data, 

ORAUT-PROC-0095, Rev. 00; June 5, 2006 

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4.3 Facility Employees and Experts 

NIOSH also reviewed information from the following three NIOSH Worker Outreach Meetings: 

•	 Meeting with University Professional and Technical Employees Local 1663 at Northern New 

Mexico Community College; Espanola, New Mexico; June 18, 2005 

•	 Meeting with International Guard Union of America Local 69; Los Alamos, New Mexico; August 

16, 2005 

•	 Meeting with New Mexico Building and Construction Trades Council; Albuquerque, New 

Mexico; June 20, 2006 

To obtain additional information, NIOSH interviewed two primary former LANL employees and 

received historical information from a current member of the LANL Radiation Protection Division. 

These employees were principal members of the LANL health physics staff. NIOSH determined 

during the preparation of this report and evaluation of the available data and process information that 

further interviews would be unlikely to locate additional information of sufficient magnitude to alter 

the evaluation’s outcome for the broad period of time and extensive number of Technical Areas 

included in this report. 

•	 Conversation with Jim Lawrence and John Voltin; discussion of external badging practices; 

Interviewer: G. Calhoun; Interviewees: J. Lawrence and J. Voltin; August 20, 2002; SRDB Ref 

ID: 7897 

•	 Interviews and Personal Communications with J. N. P. Lawrence by T. E. Widner (2003); general 

interview conducted on August 20, 2003 plus follow-up comments on the 11-03-03 draft of the 

External Dosimetry TDB; Interviewer: T. Widner; Interviewee: Jim Lawrence; 2003; SRDB Ref 

ID: 27882 

•	 Personal Communications Between Tom Widner and James N. P. Lawrence (2004); follow-ups on 

the August 20, 2003 general interview; Interviewer: T. Widner; Interviewee: Jim Lawrence; 2004; 

SRDB Ref ID: 27884 

•	 Interpretation of LANL Personnel Radiation Dose Reports; Personal Communications with John 

Voltin, LANL Radiation Information Management Team Leader (February 2005); Interviewer: T. 

Widner; Interviewee: J. Voltin; February 2, 2005; SRDB Ref ID: 27886 

•	 E-mail from Paul Hoover to Jack Buddenbaum Dated November 17, 2006, Regarding Pre-1969 In 

Vivo Results at LANL; Interviewer: T. Widner; Interviewee: Paul Hoover (LANL); 2006; SRDB 

RefID: 27881 

Additional discussions were held with the ORAU Team TBD Team Lead for LANL to clarify 

information presented in the TBDs. 

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4.4 Previous Dose Reconstructions 

NIOSH reviewed its NOCTS dose reconstruction database to locate EEOICPA-related dose 

reconstructions that might provide information relevant to the petition evaluation. Table 4-1 

summarizes the results of this review for the period of March 15, 1943 through December 31, 1975. 

(NOCTS data available as of: December 19, 2006) 

Table 4-1: No. of LANL Claims Submitted Under the Dose Reconstruction Rule 

(March 15, 1943 through December 31, 1975) 

Description Totals 

Total number of claims submitted for energy employees who meet the proposed class definition 

criteria 657 

Number of dose reconstructions completed for energy employees who were employed during the 

years identified in the proposed class definition 300 

Number of claims for which internal dosimetry records were obtained for the identified years in the 

proposed class definition 384 

Number of claims for which external dosimetry records were obtained for the identified years in the 

proposed class definition 526 

NIOSH reviewed each claim to determine whether internal and/or external personal monitoring 

records could be obtained for the employee. In a few cases, claimant interviews provided information 

that might be useful for dose reconstructions. Such information included specific TA or building 

work locations, work duties, types of monitoring, radioactive materials involved, and descriptions of 

incidents. Most of the remaining claimant interview reports did not include specific work location, 

source term, specific monitoring, or incident involvement information. 

NIOSH was able to obtain internal and external monitoring records for partial time periods and for a 

partial list of the radionuclides of concern (ROCs) at the site. Similarly, some effluent release and 

work area air monitoring records were also available for portions of the site and some of the ROCs. 

The available information has allowed NIOSH to complete dose reconstructions for 300 workers 

using either an overestimating or an underestimating dose reconstruction methodology, as described in 

NIOSH internal procedure OCAS-PR-003, Performing and Reporting Dose Reconstructions. These 

methods make use of relatively limited and case-specific information that are not necessarily 

sufficient to demonstrate the feasibility of estimating radiation doses for a class of employees (which 

may include individuals for whom these methods are inappropriate). 

More specifically, the overestimating methodology uses overestimates of radiation exposures to limit 

the need for additional research and analysis for cases that apparently did not involve a compensable 

level of radiation dose and, hence, for which a more precise determination of the doses received by the 

employees would delay, without any benefit to the claimants, the completion of the dose 

reconstructions and the resolution of the related claims. The underestimating methodology similarly 

uses underestimates of radiation exposures to limit the need for additional research and analysis, but in 

this case the dose reconstruction process is abbreviated at the point when it becomes apparent that the 

case involved a compensable level of radiation dose, allowing the claimants to be compensated more 

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expeditiously. Neither of these methods is useful when only a comprehensive and maximally-detailed 

dose reconstruction can establish whether or not the individual incurred a compensable level of 

radiation dose. 

The review of completed and pending cases included a wide variety of job titles, including: carpenter, 

electrician, machinist, chemist, security guard, technician, physicist, custodian, animal caretaker, 

vehicle inspector, and research scientist. Years of service ranged from less than one year up to 42 

years. Completed reconstructions used various approaches, both underestimates (partial 

reconstructions) and overestimates. Reconstructions that have been completed for monitored worker 

cases applied available external and internal monitoring data as well as missed dose. For cases with 

monitoring gaps, or where the worker did not have either internal or external monitoring data, the 

reconstructions relied on co-located worker data (e.g., when the worker was involved in an incident), 

technical information bulletins ORAUT-OTIB-0002 and ORAUT-OTIB-0018, ambient on-site doses 

from other DOE sites, internal co-worker data from across the DOE complex, radiological protection 

guide values, or TBD-tabulated values. 

4.5 NIOSH Site Research Database 

NIOSH also examined its Site Research Database to locate documents supporting the evaluation of 

the proposed class. Three hundred and thirty-one (331) documents in this database were identified as 

pertaining to LANL. These documents were evaluated for their relevance to this petition. The 

documents include historical background on external dosimetry programs and evaluations, internal 

monitoring, contamination monitoring, air monitoring, environmental monitoring, medical 

monitoring, process materials, and facility and process descriptions. 

4.6 Other Technical Sources 

NIOSH reviewed the following technical sources in support of the evaluation of the proposed class: 

•	 Overview of Los Alamos National Laboratory - 1997, LA-UR-97-4765; LANL Environment, 

Safety, and Health Division; 1998; SRDB Ref ID: 27224 

•	 Internal Dosimetry and Dose Assessment at Los Alamos National Laboratory, Inkret, W. C., 

LANL; 1993; SRDB Ref ID: 14522 

•	 Air Monitoring and Its Evolution at the LASL Plutonium Facility, LA-4076; LASL; 1969; SRDB 

Ref ID: 27223 

•	 History of LANL’s Bioassay Program from Inception to 1993, LA-UR-05-1942; Clark, M. J.; 

LANL; 2005; SRDB Ref ID: 17157 

•	 Brief History of Biological Monitoring and Dose Assessment for Tritium at Los Alamos, LANL, 

1987; SRDB Ref ID: 14512 

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•	 Compendium of Reports on Various Nuclides, Work Groups and Operations, Circa 1945, LASL; 

1946; SRDB Ref ID: 14878 

•	 Evaluation of Polonium-210 Exposure for Termination Reports, LANL, 1979. SRDB Ref ID: 

14519 

•	 Interim Report of the Los Alamos Historical Document Retrieval and Assessment (LAHDRA) 

Project, ChemRisk et. al.; Version 3B; July 27, 2004; SRDB RefID: 27260 

•	 Los Alamos National Laboratory (LANL) Female Cohort Mortality Study (lafema01), DOE 

Comprehensive Epidemiologic Data Resource (CEDR), 1987; CEDR site: http://cedr.lbl.gov/cgibin/spiface/find/cedrdfs/def?DATASET=lafema01 

•	 Los Alamos National Laboratory (LANL) Male Cohort Mortality Study (lamena03), DOE 

Comprehensive Epidemiologic Data Resource (CEDR), 1993; CEDR site: http://cedr.lbl.gov/cgibin/spiface/find/cedrdfs/def?DATASET=lamena03 

•	 Los Alamos National Laboratory (LANL) Female Suicide Analytic Study (lasuia02), DOE 

Comprehensive Epidemiologic Data Resource (CEDR), 1988; CEDR site: http://cedr.lbl.gov/cgibin/spiface/find/cedrdfs/def?DATASET=lasuia02 

•	 Follow-Up Study of Select Manhattan Project Plutonium Workers (laupua01)), DOE 

Comprehensive Epidemiologic Data Resource (CEDR), 1987; CEDR site: http://cedr.lbl.gov/cgibin/spiface/find/cedrdfs/def?DATASET=laupua01 

•	 Analytic Health Study of Los Alamos, Zia Company, and Manhattan Project Workers (lahswa04)), 

DOE Comprehensive Epidemiologic Data Resource (CEDR), 1987; CEDR site: 

http://cedr.lbl.gov/cgi-bin/spiface/find/cedrdfs/def?DATASET=lahswa04 

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4.7 Documentation and/or Affidavits Provided by Petitioners 

In qualifying and evaluating the petition, NIOSH reviewed the following documents submitted by the 

petitioners (received June 26, 2006): 

Submittal No. 1 (SECIS 9457 and 9460): 

•	 Initial Form B Submission 

•	 Atomic Energy Commission Release No. B-30, AEC Announces Completion of Investigation and 

Review of December 30 Radiation Accident at Los Alamos Scientific Laboratory; March 2, 1959 

•	 Attachment titled: Special Exposure Cohort Petition for Los Alamos National Laboratory 

•	 Article: U.S. to Pay Workers for Radiation Exposure; April 12, 2000; 

http://www.navajoboy.com/artus.htm 

Submittal No. 2 (SECIS 9638): 

•	 Revised Form B Submission 

•	 Attachment: In response to your request for additional information and corrections to the 

application 

•	 Atomic Energy Commission Release No. B-30, AEC Announce Completion of Investigation and 

Review of December 30 Radiation Accident at Los Alamos Scientific Laboratory; March 2, 1959 

•	 Attachment Titled: Special Exposure Cohort Petition for Los Alamos National Laboratory 

•	 Article: U.S. to Pay Workers for Radiation Exposure; April 12, 2000; 

http://www.navajoboy.com/artus.htm 

•	 Letter to Larry Elliott from Tom Udall; March 17, 2006 

•	 Letter to C. Russell Shearer from Tom Udall; March 17, 2006 

•	 Letter to H. Ruiz from L. Elliot, January 26, 2006 

•	 Letter to H. Ruiz from L. Elliot; February 7, 2006 

•	 Page from Presentation: Development of the Site Profile for the Los Alamos National Laboratory; 

August 16, 2005 

•	 Environmental Health Perspectives, Volume 110, No. 7, July 2002, Compensating for Cold War 

Cancers 

•	 Newspaper article: Sunday Journal, February 19, 2006, Bingaman Says Budgets Unfair to 

Hispanics 

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•	 Copy of web page from URL: http://www,abqjournal.com/north/_news02-04-04, Budget Could 

Accelerate Lab Worker Claims 

•	 Unknown date and source: DOL Rule for Atomic Workers’ Compensation is Born Broken; Rule 

Defies Congressional Direction and Intent 

•	 Tiger Team Assessment of the Los Alamos National Laboratory; U. S. Department of Energy 

Environment, Safety, and Health; November 1991 

•	 Letter to Mr. Milan Mikale; April 20, 1987 

•	 Six pages from a medical record 

Submittal No. 3 (SECIS 9822): 

•	 Revised Cover sheet and Form B submission including F.2 as the submission basis 

•	 Exhibit A: Affidavit from R. Chavez 

•	 Exhibit B: Affidavit from R. Chavez 

•	 Exhibit C: Dosimetry records for R. Ruiz 

•	 Exhibit D: Powerpoint presentation, Development of the Site Profile for LANL 

•	 Exhibit E: Affidavit from H. Ruiz 

•	 Exhibit F: Affidavit from D. Cooper 

•	 Exhibit G: Affidavit from D. Cooper 

•	 Exhibit H: Affidavit from M. Martinez 

•	 Exhibit I: Affidavit from L. Martinez 

•	 Exhibit J: Affidavit from J. Garcia 

•	 Exhibit K: Affidavit from A. Serrano 

5.0 LANL Radiological Operations Relevant to the Proposed Class 

The following subsections summarize both radiological operations at LANL from March 15, 1943 to 

December 31, 1975 and the information available to NIOSH to characterize particular processes and 

radioactive source materials. From available sources NIOSH has gathered process and source 

descriptions, information regarding the identity and quantities of each radionuclide of concern, and 

information describing both processes through which radiation exposures may have occurred and the 

physical environment in which they may have occurred. The information included within this 

evaluation report is intended only to be a summary of the available information. 

NOTE: Throughout this evaluation report, the term “LANL” will be employed to refer to all historical 

phases of, and successive names for, the Los Alamos site. 

5.1 LANL Plant and Process Descriptions 

Security was the overriding consideration in the selection of the site originally known as Site Y, later 

the Los Alamos Scientific Laboratory, and finally the Los Alamos National Laboratory (in 1981). 

The basic selection criteria were that the site be in an isolated, relatively remote, and inaccessible 

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location. Accordingly, the search was first narrowed to the sparsely-populated areas of northern New 

Mexico and southern Nevada. The search then refined its focus on two sites - Jemez Springs and the 

Los Alamos Ranch School near Otawi (approximately 50 miles north of Albuquerque). After a 

November 1942 site visit, General Leslie Groves selected the Los Alamos site as the location for the 

new laboratory. Discussions with the owners of the school revealed a willingness to immediately sell 

their privately-held land and vacate. On November 25, 1942, Groves received authorization to 

acquire the site. By month’s end, supervision of Site Y initial construction had been assigned to the 

Corps District Engineer in Albuquerque. By year’s end, the University of California had assumed 

responsibility for procuring supplies and personnel (Hewlett and Anderson, pp. 229-230; Smyth 1945, 

p. 207). 

The start date for the Los Alamos site can be reasonably considered March 15, 1943. Although the 

existing school buildings enabled some personnel to move to the site and immediately begin 

preliminary work, Laboratory Director J. Robert Oppenheimer and a few of his staff did not arrive 

until March 15, 1943. They were housed near the site in guest houses that were once part of the 

school. Other personnel were housed in nearby ranches or in Santa Fe. Work with radioactivity, 

specifically plutonium and enriched uranium, would not be carried out for some months (i.e., until 

these materials could be produced in sufficient quantity at Hanford and Oak Ridge). The first work 

with plutonium apparently took place in mid-1943. In May 1943, Site Y requested a 14-day loan of 

200 micrograms of plutonium from the plutonium project in order to experimentally measure fission 

neutron production and yield (Kathren, Gough and Benefiel, pp. 277-8). 

As the requested quantity was half the extant world supply of plutonium, great care was taken to avoid 

the loss of even a single atom of the material, which was personally brought to the site by Glenn T. 

Seaborg. Experimental work with this tiny quantity of plutonium was carried out in July 1943 in 

Technical Area (TA) 1 (Hewlett and Anderson, p. 212). 

Early plutonium studies at Los Alamos had to be carried out on a micro-chemical basis because even 

milligram quantities of the material were unavailable. Not until the spring of 1944 were gram 

amounts of plutonium available from the Clinton Pile at Oak Ridge (Hewlett and Anderson, p. 243­

245). In March 1944, the first shipment of enriched uranium was received: a portion of the 200 grams 

of 12 percent-enriched material that had been thus far produced in the Alpha 2 racetrack at Oak Ridge 

(Groves, p. 110; Hewlett and Anderson, p. 164). Shipments of plutonium from the Hanford 

production reactors to Los Alamos did not begin until early 1945; the first small sample of plutonium 

arrived on February 2, 1945. 

The Los Alamos laboratory initially had a single mission: design and manufacture of the first nuclear 

weapons. This entailed a great deal of both experimental and theoretical research, particularly with 

regard to fission of U-235 and Pu-239 by neutrons and the production of fission products. Related 

work was also performed on the chemistry, metallurgy, preparation, and assembly of the weapons’ 

nuclear components. Los Alamos was charged with fabricating the fissile components of the 

weapons, which included machining metallic plutonium and uranium to exacting tolerances. 

Neutronics studies required construction of two small test reactors and a number of critical facilities. 

In addition, a great deal of non-radiological work was carried out involving high explosives and other 

ancillary weapons components. By mid-1943, the organization to carry out this mission had been 

finalized as four divisions reporting to Director Oppenheimer: Theoretical, Experimental Physics, 

Chemistry and Metallurgy, and Ordnance. The efforts of these four divisions and the myriad other 

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sites working to provide component materials resulted in the deployment of two nuclear devices that 

brought an accelerated end to the war in the Pacific. 

After World War II, many scientists (particularly those with greater prominence and seniority who 

had worked on the first nuclear weapons) left Los Alamos and the weapons development and testing 

program shrank and began to wind down. In 1946, responsibility for the lab was transferred from the 

military to the newly-created civilian Atomic Energy Commission (AEC). 

By mid-1947, there was a resurgence of activity at the then-renamed Los Alamos Scientific 

Laboratory (LASL). Aided by a large construction budget the following year, the much more 

broadly-defined mission included development of fast neutron reactors and thermonuclear weapons 

research. These projects brought with them new radiological concerns, specifically doses from 

neutrons and tritium. Los Alamos remained the lead facility for the fabrication of nuclear components 

for weapons until 1949, when the Plutonium Finishing Plant at the Hanford site in Washington State 

began making the central cores for nuclear devices. However, LASL remained a back-up production 

facility. In addition, the lab designed, developed, and fabricated nuclear components for test devices, 

a function that has continued throughout its lifetime. Furthermore, its work broadened to include a 

wide spectrum of radiologically-related research and operational activities. Weapons development 

and testing remained central; however, the broadened mission also included fission product studies, 

isotope applications, reactors, and advanced accelerators, such as the Los Alamos Meson Physics 

Facility (LAMPF) and Project Sherwood, and the Kiwi reactor program assigned to the lab in 1957 

(Hacker pp. 200-205). Many of the LASL programs, especially the weapons development and testing, 

were carried out in parallel with what is now the Lawrence Livermore National Laboratory, a second 

weapons laboratory started in 1952 (Hewlett and Duncan, pp. 583-4). 

The diversity and breadth of research and other work involving ionizing radiation at the site is 

enormous, but over the years, nuclear weapons development, testing and related activities have been 

the dominant activities. Much of the weapons-testing work involving actual detonation of nuclear 

devices was conducted off site, generally at the Nevada Test Site (NTS) (which became operational in 

1951) and the Pacific Proving Ground (PPG) (where the initial tests were conducted). In addition, 

research and other activities involving reactors and critical assemblies have been a significant part of 

the LANL mission. Most known radionuclides have at one time or another been present at the site. 

The large scope and wide breadth of site activities involving radiation and radioactive materials also 

include early biomedical studies of tritium and plutonium, experimental application of mesons to 

medical therapy, fission product studies, dynamic testing of uranium, neutron cross-section 

measurements, source development, criticality studies, reactor developments, and controlled fusion. 

These are but a few of the more significant radiologically-related activities carried out over the years. 

Another significant site activity during the period under evaluation was the implosion testing 

involving radioactive lanthanum (RaLa), conducted from September 21, 1944 through March 6, 1962. 

These activities are the subject of an SEC class that includes potentially-exposed workers from this 

program, as defined in the Evaluation Report for Petition SEC-00061 (covering the time period 

September 1, 1944 through July 18, 1963). Therefore, the report herein does not evaluate the 

feasibility of dose reconstruction for RaLa activities, with the exception of potential dose resulting 

from residual strontium-90 contamination after July 18, 1963. 

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5.2 LANL Functional Areas 

To accomplish its mission, LANL was divided into a number of physically separate Technical Areas 

which spread in time over a relatively large area. No less than 75 numbered TAs have been identified 

along with several off-site locations. These TAs and locations, along with their significant radiation 

sources, are briefly described in Table 5-1. The tabulation of radiation sources is, of necessity, 

incomplete and only an overview; more detailed information is available in ORAUT-TKBS-0010-2. 

In addition to the potential intakes of the radiation sources specifically identified, personnel at the sites 

where radiation sources or radiation-generating machines were present also had the potential for 

exposure to external radiations from beta radiation, gamma rays, and neutrons. 

Twelve of the TAs listed in Table 5-1 had no known history of radioactive material use or were not 

operational during the evaluation period and are, therefore, excluded from this evaluation. Other TAs 

listed with an unknown history are assumed to have had some exposure potential and are thus 

considered in the proposed class definition. 

Historically, the diverse nature of LANL work, the large number of specific programs, and the 

numerous areas both on and off site where activities were carried out does not lend itself to a detailed 

evaluation of each specific functional or technical area. To some extent, this evaluation was 

accomplished in ORAUT-TKBS-0010-2, which also gives a detailed chronology of site facilities 

construction. 

A more representative picture of the laboratory can be obtained by an overview of the site’s main 

functional areas of activity: 

• LANL Weapons Development and Testing (Section 5.2.1) 

• LANL Critical Assemblies, Reactors, and Reactor Development (Section 5.2.2) 

• LANL Accelerators, X-ray Equipment, and Radiography Sources (Section 5.2.3) 

• LANL Biomedical Research (Section 5.2.4) 

• LANL Project Sherwood and Fusion Research (Section 5.2.5) 

• LANL Waste Treatment and Disposal (Section 5.2.6) 

Additional information regarding LANL functional activities can also be found in ORAUT-TKBS0010-2. 

5.2.1 LANL Weapons Development and Testing 

LANL’s long-standing central mission, to which major portions of its efforts were devoted, was the 

development and testing of nuclear weapons. This work involved extensive studies with enriched and 

depleted uranium and plutonium. From the outset, it was recognized that uranium enriched in U-235, 

and subsequently Pu-239, could be made to produce an uncontrolled chain reaction of nuclear fissions. 

This reaction would involve an enormous release of energy, including a burst of gamma and neutron 

radiations, and the production of a wide range of fission products with atomic numbers ranging from 

30 (zinc) to 65 (terbium), with 97 percent of the nuclei produced by U-235 thermal fission having 

mass numbers from about 85 to 104 and 130 to 140 (Glasstone p. 481-3). Most fission products are 

radioactive, with half-lives ranging from a fraction of a second to a few weeks or months; a few, such 

as Sr-90 and Cs-137, have much longer half-lives of approximately 30 years. In addition to the more 

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than 100 radioactive nuclear species produced by the fission process, there are other radioactive 

species produced by neutron activation of the casing and other components of the device, most 

notably the production of radioisotopes of the heavy elements, in particular plutonium. 

Work at LANL centered around not only the neutronics of the fission process but also the chemistry 

and metallurgy of uranium and plutonium, the identification and characterization of fission products, 

and the development and characteristics of thermonuclear devices. Fission product studies required 

sampling, collection and transport of radioactive samples from the off-site nuclear testing locations to 

Los Alamos. 

Examples of other significant LANL weapons-related activities involving radioactivity include a large 

number of experimental implosion diagnostics studies carried out between 1944 and 1961, with 

La-140 used as a surrogate for fission product activity and either natural or depleted uranium as a 

surrogate for the fissionable material. RaLa experiments took place at TA-10, which included several 

buildings and four outdoor firing sites. La-140 separations took place in the radiochemistry building, 

TA-10-1. In 1951, the La-140 separations operation was moved to TA-35, commonly referred to as 

the “Ten Site.” This operation remained at TA-35 until the end of the project. Other RaLa-related 

activities took place on a much smaller scale in Buildings Sigma, H, and U, all located in Technical 

Area 1 (TA-1). These studies were significant not only for the large amount of radioactive lanthanum 

used (301,802 Ci) but also in that this activity, along with Sr-90, was directly released to the 

environment. The LANL Director notified the AEC in a letter dated July 18, 1963 that the TA-10 site 

clean-up was complete. The evaluation herein only addresses residual contamination from RaLa 

activities after July 18, 1963. 

Research on high explosives was carried out in a number of TAs from 1949 to 1970, and used tens of 

tons of depleted uranium, much of which was directly released into the environment. 

Weapons tests were carried out largely at PPG and NTS, although several tests were conducted at 

other locations within the United States. Testing at PPG ceased in 1962 with the signing of the Test 

Ban Treaty, but LANL still maintained a presence there, conducting (among other things) radioecological studies. The first nuclear weapon test was the Trinity tower shot at Alamagordo, New 

Mexico, in August 1945. Six other tests, primarily non-weapons-related, were conducted in the 1960s 

and 70s in Alaska, Colorado, and New Mexico. A few weapons-related tests were conducted at 

Tonopah, Nevada (adjacent to NTS), and some near Hattiesburg, Mississippi. 

5.2.2 LANL Critical Assemblies, Reactors, and Reactor Development 

From the outset, criticality experiments were conducted, often to determine the critical mass of U-235 

and Pu-239 needed for weapons and to gather other neutronics data. These experiments were initially 

carried out at TA-2, Omega Site, which had been designated for this purpose as well as the site for 

research reactors in 1943. Subsequently, these experiments were conducted at TA-18, Pajarito Site, 

which was originally developed in mid-1943 for radioactivity studies. Some criticality studies were 

moved to TA-18 in April, 1946 following a fatal criticality accident; the entire critical experiments 

group was relocated there from TA-1 in February 1953. Initially, criticality experiments were done in 

the open and hand-controlled, but fatal criticality accidents led to the institution of safety measures, 

including a ban on hand operations. Critical assemblies were used to generate pulses or bursts to 

simulate weapons detonations. These included the various Godiva assemblies, Jezebel, and SHEBA, 

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which was assembled in the 1950s. The critical assembly cores were composed of uranium enriched 

in the U-235 isotope, Pu-239, or U-233. 

The reactors at Omega Site were small test devices, essentially uncontained. The first of these, a 

zero-power water boiler fueled with 14 percent enriched uranium, achieved initial criticality in May 

1944. The boiling water reactor operations continued. Subsequently, in 1945, the Plutonium Fast 

Reactor dubbed Clementine was approved and achieved initial criticality in August 1946, ultimately 

reaching its design power of 25 kW in March 1949. Technical problems with Clementine resulted in 

its shutdown in 1950; it was replaced by the Omega West Reactor, which had a design basis of 5 MW. 

Clementine was decommissioned in 1953; Omega West continued operations until 1992. After 

criticality operations were moved to TA-18 in 1946, reactor operations at TA-2 were largely 

concerned with neutron studies and isotope production. 

A number of other reactors were constructed and operated by LANL. The Los Alamos Power Reactor 

Experiment (LAPRE) was carried out at TA-35 between 1955 and 1960. This was followed by the 

Los Alamos Molten Plutonium Experiment (LAMPRE), which operated through the 1960s. 

TA-35, also known as Ten Site, housed a number of other non-reactor operations, including La-140 

separation cell and fusion research. 

Project Rover was a major reactor research project that attempted to develop a practical nuclear 

rocket. No less than 16 Project Rover reactors (which included the Kiwi reactors) were developed by 

the Critical Experiments Group at TA-18 (Pajarito Site) between 1959 and 1972. These reactors were 

made and assembled in TA-18 where they underwent initial testing prior to being shipped to NTS 

where they underwent additional rigorous (and sometimes destructive) testing. Project Rover was 

terminated in 1973. Another significant reactor program was the helium-cooled Ultra-High 

Temperature Reactor Experiment (UHTREX). The UHTREX was constructed at TA-52 during the 

late 1960s; it only operated for about a year before being terminated in 1970. The facility was 

decontaminated in the 1980s. 

Evaluations of reactor fuel elements and spent fuels were also associated with reactor projects. These 

activities were performed within hot cells located in TA-3, -21, and -48. 

5.2.3 LANL Accelerators, X-Ray Equipment, and Radiography Sources 

Accelerators have been present at the Los Alamos site since its inception. Initially, accelerators were 

used to generate neutrons to determine the critical masses of U-235 and Pu-239, to study Pu-239 

pre-detonation characteristics, and to perform cross-section studies. Four accelerators were obtained 

from various universities and used during the war years: two Van de Graaff generators, a CockcroftWalton Machine, and a cyclotron. After the war, the Long Tank van de Graaff generator was 

returned to the University of Wisconsin and was replaced with a more modern unit with a vertical 

configuration. The other three units remained at Los Alamos. Additional accelerators were soon 

added, including: a small betatron; linear electron accelerators; small accelerators that generated 14 

MeV neutrons by the deuterium-tritium reaction; and a van de Graaff accelerator in W building in 

TA-1 used to generate viable energy neutrons by the (p,n) reaction for cross-section studies. 

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The largest, and perhaps, most significant and unique accelerator at LANL is the LAMPF, located in 

TA-53. The LAMPF is an 800 MeV, 1 mA proton linear accelerator and one of just three facilities 

worldwide created for production of mesons. Construction on LAMPF began in 1968, and the full 

energy beam was first achieved on June 12, 1972. LAMPF was designed to produce an intense beam 

of protons with energy just above the pion production threshold, thereby producing an intense beam of 

subatomic particles. Originally, the purpose was to produce mesons and other subatomic particles in 

quantities large enough to be more readily studied. Later, the LAMPF was used for neutron-scattering 

studies. By means of its Proton Storage Ring, the LAMPF can generate high-intensity neutron pulses 

by proton bombardment of high Z targets, including uranium. 

Because of its large size and unique capabilities, LAMPF produces a wide variety of radiations and, 

since at least the late 1970s when monitoring for short-lived activation gases began, has been the 

foremost source of airborne radioactivity releases to the environment. 

X-ray equipment and/or radiography sources were used for non-destructive testing in TA-8, -13, -15, 

-16, and -24. In the 1960s, the Pulsed High Energy Radiographic Machine Emitting X-Rays 

(PHERMEX) became operational in TA-15. To simulate a radiation pulse from a nuclear detonation, 

PHERMEX produced pulsed X-rays by impinging a beam of electrons onto a tungsten target. Other 

X-ray equipment with potentials of up to 1 MeV, some of which were portable, were used to examine 

explosive casings, materials, dies, and molds. Radiography sources used in similar non-destructive 

testing included Co-60, Cs-137, and Ir-192. 

5.2.4 LANL Biomedical Research 

The Biomedical Research group conducted numerous studies on radiological interactions and the 

medical use of radioactive materials. These studies involved the radiolabeling of various compounds. 

The radionuclides most commonly employed in these research efforts were C-14, H-3, P-32, S-35, 

and radioactive iodines. 

5.2.5 LANL Project Sherwood and Fusion Research 

Controlled nuclear fusion research began in 1951 and was carried out under the auspices of Project 

Sherwood, a nationwide part of the Atoms for Peace Program. The initial work was carried out in 

TA-1 using the betatron, which had been modified for this purpose to induce a toroidal current in a 

plasma, which in turn produced a magnetic field that pinched or constricted the plasma column. This 

process, known as the Z-pinch, was unsuccessful but encouraging, and led to construction of more 

advanced accelerators to obtain the extremely high temperatures needed for a fusion reaction. 

Although Project Sherwood was discontinued in the 1970s, thermonuclear fusion research continued 

at LANL. Construction of laser fusion laboratories for fusion research began at TA-35 in 1974; 

HELIOS and ANTARES are large laser facilities for the study of plasma containment by laser inertial 

confinement. 

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5.2.6 LANL Waste Treatment and Disposal 

The site’s initial waste management consisted of direct discharge of untreated liquid wastes to Acid 

Canyon from the mid-1940s until 1951. An exception was waste solutions containing plutonium, 

which were collected in storage tanks in TA-21 for eventual plutonium recovery. From the early 

1950s onward, various liquid waste treatment facilities were placed into operation in TA-21, -35, -45, 

and 50. These facilities treated waste using flocculation-sedimentation-filtration, absorption beds, 

hold-up tanks to allow for radioactive decay of short-lived radionuclides prior to discharge, 

de-ionization, and grouting followed by ground shaft injection. Treated liquids were then discharged 

to various canyons. 

Solid wastes were disposed of primarily in material disposal areas. These disposal areas are located in 

TA-4, -21, -33, and TA-54 (the central waste disposal facility which began operations in 1957 for 

low-level radioactive waste). The remaining solid waste facilities were used in the mid-1940s and 

ceased operations at various timeframes between the 1950s and 1970s. 

Incinerators were also used primarily for volume reduction and, in some cases, for material recovery 

(specifically U-235). These incinerators were located at TA-1, -3, -21, and -42. 

5.2.7 Summary of Key LANL Facilities 

Table 5-1 summarizes the LANL TAs, key processes, dates of operation, and primary radiation 

sources. Twelve of the listed TAs had no history of radioactive material use or were not operational 

during the period of this evaluation: TA-1-Z, TA-17, -19, -28, -34, -38, -57, -64, -65, -69, -70, and 

-74. 

The following abbreviations apply: 

•	 a.k.a. = Also known as 

•	 All = Pu-239, Pu-240, Pu-238, Am-241, U-235, DU, H-3, Po-210, Ac-227, Ra-226, MAP, MFP, 

NU, VFP 

•	 NA = Not applicable 

•	 NCD = No confirmed date 

•	 DU = Depleted uranium 

•	 EU = Enriched uranium 

•	 HT = Tritium gas 

•	 HTO = Tritium oxide 

•	 MAP = Mixed activation products (e.g, C-11, N-13, O-15, Ar-41, Be-7, Na-22, Na-24, Co-58, Co57, Mn-54, Mn-52, V-48, and others) 

•	 MFP = Mixed fission products (e.g. Cs-137, Sr-90, radioactive noble gases, and others) 

•	 NU = Natural uranium 

•	 TRU = Transuranic materials 

•	 VFP = Volatile fission products 

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Table 5-1: LANL Technical Areas, Operational Dates, and Radionuclides 

Location Start Demolished or Decomm. Radionuclides 

TA-0: Los Alamos Town site: Leased space in Los Alamos and White Rock 

for training, support, unclassified research and development, community outreach, museum 

NA NA None Origina

TA-1 (General): Original Main Technical Area (inactive): Active 1943-65; turned 

over to Los Alamos County or private interest in 1966; all contamination removed by 1975. 

1943 1965 active 

1975 decomm. 

See TA-1 entries below. 

TA-1-C, Uranium machining 1943 1964 Uranium 

TA-1-D, Pu chemistry and metallurgy 1943 1954 Pu-239, Pu-238, U-238, DU 

Am-241 Po-210 Ba-140, La-140 

AbsorpMay in

TA-1-D-2, Contaminated laundry 1943 1953 Pu-239; Pu-240; Pu238; 

Am-241, EU, DU, Po-210, Ac-227, Ra-226 

TA-1-D-5, Sigma vault - storage NCD 1965 Pu-239, U-238 

TA-1-G, Uranium and graphite sigma pile NCD 1959 Uranium, Ra-226 TA-1-H and Gamma. 1945 1957, 1959 Po-210 

MFP 

InitiatoCs-137 

TA-1-HT, Heat treatment and machining 1946 1965 NU, EU TA-1-HT, Barrel House, Storage NCD 1964 Pu-239, U-238 TA-1-M, Processing and recovery EU NCD NCD EU ProcessTA-1-M-1, Machining NCD NCD U-238 

TA-1-ML, Medical Laboratory NCD NCD Cm, Am Process

TA-1-O 1943 1956 Radon, 

Radium 

Radon Ra /RaB

TA-1-Q 1943 1959 Radium 

Radon 

A spill Ra Cali

TA-1, Sigma Bldg 1944 1965 NU, EU, Th Casting

Page 26 of 117 
SEC-00051 02-01-07 

Table 5-1: LANL Technical Areas, Operational Dates, and Radionuclides 

Location Start Demolished or Decomm. Radionuclides 

TA-1-TU, Machining Tuballoy NCD 1964 NU TA-1-TU-1, Recovery of EU NCD 1964 EU Furnace 

TA-1-V, Machine Shop 1943 1959 uranium Unusua

TA-1-W, Van de Graaff accelerator 1943 NCD uranium, Po-210, H-3 

Th-228 “Mesio

TA-1-X, Cyclotron 1943 NCD Be, U, Li, H-3, Sr targets. 

Zn-65 

Targets 

TA-1-Y, Physics Laboratory 1943 NCD H-3, Uranium 

TA-1-Z, Cockcroft-Walton accelerator 1943 NCD None 

TA-2, Omega Site (General): Early critical assembly experiments. Reactors were used for critical experiments until 1946 when the experiments were moved to TA-18. After 1946, Omega Site reactor operations focused on neutron experiments and isotope production. 

Early 1940s Major decomm. 

activity in 1991 

See TA-2 entries below. 

TA-2, Water Boilers 1944 1974 EU, 

I-131, I-125, Rb-88, Cs-137, Xe-131, Ar-41, H-3, Pu-239 

EnricheNeutron

TA-2, Pu Fast Reactor, a.k.a. Clementine (1946–1952) 1946 1953 NU, Pu, I-131, I-125, 

Rb-88, Cs-137, Xe-131, Ar41 

RuptureNeutron

TA-2, Omega West Reactor (OWR) (1956-1992) 1956 1995 U-235 

I-131, I-125, Rb-88, Cs-137, Xe-131, Ar41, Cr-51, Na-24, Tc-99m 

EnricheI-125 poperateNeutron

TA-3, Core Area a.k.a South Mesa Site (General): Detonator manufacturing, 

metallurgy burn pit, firing sites (1943-49). 

1943 Still active See TA-3 entries below. 

TA-3-34, Cryogenics Laboratory NCD NCD H-3 3,000 C

TA-3-35, Press Building (part of Sigma Complex) NCD NCD EU 

27 of 117 
SEC-00051 02-01-07 

Table 5-1: LANL Technical Areas, Operational Dates, and Radionuclides 

Location Start Demolished or Decomm. Radionuclides 

TA-3-66, Sigma Complex, metallurgy and fabrication NCD NCD EU, DU powders, Pu, 

thorium 

Pu pro

TA-3-102, Machine shops; NCD NCD uranium, Pu, DU TA-3-141, Rolling Mill (part of Sigma Complex) NCD NCD DU, Pu, EU, thorium TA-3-159, Thorium Storage (part of Sigma Complex) NCD NCD thorium TA-3-184, Occupational Health NCD NCD Pu TA-3-216, Weapons Test Support NCD NCD Pu TA-3-1698, Materials Science Laboratory: Processing, mechanical research NCD NCD DU 

TA-3-FE-19 NCD NCD Plutonium TA-3-SM-16, Ion Beam Facility (IBF); Van de Graaff – Accelerator and Tritium 

operations 

NCD NCD I-125 

H-3 P-32 

Iodide, Labeled HT Labeled Neutron

TA-3-SM-29, Chemical and Metallurgical Research (CMR); actinide chemistry and 

metallurgy research (1952 to present) 

1951 Still active Pu-238, Pu-239,EU, U-238, 

DU 

Small qmixed f238 

TA-3-SM-29, Chemistry and Metallurgy Bldg., Wings 3, 5, and 7 NCD NCD H-3 HTO, HTA-3-SM-29 Chemistry and Metallurgy Bldg., Wing 9; handling of irradiated U and Pu in hot cells. 

1961 NCD Cs-137 

MFP including I-131, Pu-238, Pu-239, Pu-240 EU, U-238, DU 

Potenticell wo0.1-10μ metal. 

TA-3-SM-40, Physics NCD NCD All Inciden

with Poearly 19

TA-3-SM-40, Tritium Instrument Calibration Facility NCD NCD H-3 HTO, HTA-3-SM-700, Acid Neutralization and Pump Bldg. NCD NCD Pu 

28 of 117 
SEC-00051 02-01-07 

Table 5-1: LANL Technical Areas, Operational Dates, and Radionuclides 

Location Start Demolished or Decomm. Radionuclides 

TA-4, Alpha Site: Constructed in 1944 as a test firing site for small-to-medium 

explosives. Firing site until 1956; Material Disposal Area C. During the summer of 1985, a clean-up operation was initiated as part of the Los Alamos Site Characterization Program. All remaining structures and their utilities were removed. 

1944 1956 

1985 

DU Firing s

TA-5, Beta Site: Former firing site used extensively in 1945. Site was constructed in 1944 as a test-firing site. Environmental contaminants at this site may include natural or depleted uranium, metallic beryllium, and/or cadmium. Burial of debris of firing sites during the years prior to 1985. 

1944 <1985 DU 

TA-6, Two-Mile Mesa South Site: In 1944 and 1945, several buildings were constructed for detonator work, including three firing chambers, laboratory, and explosives pressing shop. In 1946 and 1947, pits (now MDA F) were dug on the mesa to bury classified objects. About 100 lenses constructed at S-Site were defective and destroyed by detonation, probably in area known as MDA F. Test firing continued at TA-6 until 1952 when operations were moved to TA-40. Explosives development and laser, chemical laboratory continued at TA-6 until 1976. Several small operations (e.g., carpenter shop cable fabrication shop) continued until 1980s. Ten magazines and other buildings were removed or destroyed by burning. As of 1998, some structures were still in place, but no longer used. 

1944 1998 DU, Cs-137, Sr-90, Co-60 Detona

TA-7: Gomez Ranch Site: Former firing site used from 1944-47 for small 

explosive experiments with short-lived radionuclides. 

1944 1947 DU, unknown 

TA-8, GT Site a.k.a. Anchor Site West: Gun firing sites 1943-45. Occasional 

tests performed using small quantities of polonium and beryllium, although no indications that these materials escaped targets. Gun-Firing Site abandoned in 1946 and guns and other items buried in pit on site now know as Material Disposal Site Q. Explosives processing 1945-50. Wooden structures removed at various times between 1949 and 1968. In 1949 and 1950, modern TA-8 was established north and west of Gun-Firing Site and is presently used, primarily for non-destructive X-ray testing. 

1943 Old: 1950 

New: Active 

Pu-239, Pu-238, EU, DU, Co-60, Ir-192, Cs-137 

Gun fir

29 of 117 
SEC-00051 02-01-07 

Table 5-1: LANL Technical Areas, Operational Dates, and Radionuclides 

Location Start Demolished or Decomm. Radionuclides 

TA-9, Anchor Site East a.k.a. Anchor Ranch, Old Anchor East, Far 

(Detonation) Point, Nu Site. Nu Site was known as TA-23 before incorporation into TA-9 in 1950. Old Anchor East was established in 1943 to house explosives production, development, test experiments, and X-ray work. Old Anchor East returned to AEC in 1957; permission for site decommission given in 1959; buildings and substructures removed between 1960 and 1965. Buildings known to contain radioactive contamination removed and disposed at TA-54. Far (Detonation) Point established in 1944 to conduct explosives detonation experiments in the open. Abandoned in late 1940s and decommissioned in 1965. MDA M at Far (Detonation) Point was used from 1948 to 1985 as surface dump for construction debris, other solid wastes, chemicals, and high explosives. Construction of TA-9 (New Anchor East) began in 1950 and currently contains a laboratory and office buildings, six magazines, a shop, two laboratory buildings, process laboratories, a machining building, and an environmental test chamber where explosives research is conducted. 

1957 1960-65 DU, H-3, Sr-90 

TA-10-CMR-10, Bayo Canyon Site: Radioactive lanthanum test shots 1944-61; 

radioactive lanthanum radiochemistry 1944-50; site removed in 1963. In 1944, Bayo Canyon began to be used for firing experiments. In 1945, additional permanent structures were completed for chemistry work and firing. Best estimates are that from 1944 until 1961 (when firing ceased), approximately 2,000 kg of natural uranium and 3,380 kg of depleted uranium were released. In 1963, all remaining buildings were removed. 

1944 1963 Sr-90, DU, NU 

La-140, Ba-140 RaLa ra

TA-11, K Site: Implosion studies; later high explosives, drop and vibration 

tests. TA-11 was constructed in the winter of 1944-45. The eastern part of the site was constructed of a heavily-bunkered control/laboratory building, shop, laboratory, storage building, and smelter. 

1947 Still active Ra-226, DU, H-3 20-MeV 

Neutron

30 of 117 
SEC-00051 02-01-07 

Table 5-1: LANL Technical Areas, Operational Dates, and Radionuclides 

Location Start Demolished or Decomm. Radionuclides 

TA-12, L Site: Explosives testing. Constructed in 1944 for the Explosives 

Division (X-Division). Original structures included a trim building, control chamber, magazine, and a below-ground, steel-lined firing pit which was used from 1946 to 1953, when it was abandoned. One test in the structure involved a 154-lb (70 kg) sphere of uranium; other materials used included U-238. The burn site was used once to dispose of 0.5 lb of explosives by burning. An open section of the site was used for several months as a firing site for explosive charges. This site was abandoned by X-Division in 1946. By 1951, the explosives testing group GMX-2 occupied TA-12. Shots using uranium, lead, and He were conducted at the firing site, which was abandoned in the 1950s. In 1950, the Biomedical Group (H-4) constructed a bermed radiation test bunker and conducted animal irradiation experiments using a 1000-Ci sealed radioactive source of La-140 in transient equilibrium with Ba-140. L-Site was 

abandoned in 1953. Most of the structures were decontaminated and decommissioned (D&D) in 1960. 

1948 mid-1960s DU, U-238, La-140, Ba140, Sr-90 

TA-13, P Site: Constructed in early fall 1944 for X-ray work in connection 

with explosives experiments (LASL HD, 1947); later incorporated with 

TA-16, status unknown. By the 1950s, all buildings except TA-13-2, -3, and ­4 had been removed. These buildings were absorbed into the S Site Complex, TA-16, and were re-numbered TA-16-476, -477, and -478, respectively. 

1944 1950s DU, Po-210 X-rays 

TA-14, Q Site: Explosives testing 1944-present. Constructed in 1944 for close 

observation work on small explosive charges. In 1952, the site was completely renovated and several structures were removed. In the early 1950s, a new extensive firing complex was built and remains at the site today. During its long history, TA-14 has remained an active firing site. 

1944 Still active DU 

In late 1980s, EU, Cs-137, Co-60 detected in waste ash samples from incinerator; H-3 in storage building. 

31 of 117 
SEC-00051 02-01-07 

Table 5-1: LANL Technical Areas, Operational Dates, and Radionuclides 

Location Start Demolished or Decomm. Radionuclides 

TA-15, R Site: In 1944, a small control building and two firing sites were 

established. Additional firing sites were established and abandoned over the years. Firing Point C was established in 1945 and in use until 1948; it was decommissioned in 1967. Firing Points E-F were established in 1947 and used extensively through 1973. The site was last used in 1981. Firing Point R-44, used for larger explosive tests, was built in 1951 and used extensively from 1956 to 1978 for diagnostic tests of weapons components. Since the mid1980s, this site was used only for small experiments, the last being conducted in 1992. Firing Point R-45, the least-used of the active firing sites at TA-15, 

was built in 1951 and only used for small quantities of explosives. As of July 1998, R-45 still retained active status. Ector Firing Site, used from the mid1980s, was used for dynamic radiography of explosion-driven weapons components. The use of the site has not been extensive. Pulsed High-Energy Radiation Machine Emitting X-Rays (PHERMEX) 1962-present. PHERMEX is a multiple-cavity electron accelerator capable of producing a very large flux of X-rays for weapons development testing. DARHT is intended to replace PHERMEX. In 1949, firing sites J and I were in operation but were later transferred to Kappa Site (TA-36). Several structures were removed in 1967. 

1944 Still active Pu-239, DU, H-3 

In late 1980s, Cs-137, EU, U-238, Co-56, U-234, Th-230 detected in firing site soil samples. 

PHERMX-rays 

TA-16, S Site, Weapons Engineering Tritium Facility (WETF): Former explosives 1945 Still active Pu-239, DU Explosi

casting/machining operations; burning ground; TA-16 is the WETF for tritium H-3 Labeled handled in glove boxes. Built in 1945 to make full-scale castings. The WETF U-238 HT facility at TA-16 replaced the tritium facility at TA-33. TA-16 as a whole was constructed in 1944 and consisted of six buildings including a steam plant. Multiple buildings at this site were demolished in the 1950s and 1960s. 

In late 1980s, Cs-137, Pu-239, Pu-240, Pu-238 were detected in samples 

X-rays 

from the sewage treatment plant; U-235 in samples of two discharge outfalls 

TA-17, X Site canceled NA None 

32 of 117 
SEC-00051 02-01-07 

Table 5-1: LANL Technical Areas, Operational Dates, and Radionuclides 

Location Start Demolished or Decomm. Radionuclides 

TA-18, Pajarito Canyon Laboratory: First developed in August 1943 by Group 

P-5, the Radioactivity Group, to study rates of spontaneous fissions from samples of radioactive materials. In 1944, Group G-3 took over the site, enlarged it and used it as a proving ground to study implosions. At this time, three firing sites were constructed: the first to study small explosive charges of 

a few pounds; the second to study medium explosive charges; and the third (Far Point – not to be confused with the Far [Detonation] Point at TA-9) to test charges of up to two tons. Far Point at TA-18 was later incorporated into Gamma Site which was then re-designated TA-27. Late in 1945, explosives testing by G Division ended. This group moved to the East Gate Laboratory. In April 1946, the site was transferred to Group M-12, Critical Assemblies Group. This became the nation’s first critical assembly facility. A heavilybunkered laboratory was built at the junction of the two canyons, and a trimming building and magazine were constructed back along the road toward Anchor Ranch. In 1947, after a fatal hand-on criticality experiment accident, remotely-controlled criticality experiment structures called Kivas were constructed. Kiva 1 was built in 1947. In 1951, office building and a second Kiva were constructed. Additional buildings were constructed between 1949 and 1951 and a third remotely-controlled Kiva was added in 1960. From 1955 to 1972, fission reactor mock-up studies for the Rover Program were conducted at these Kivas. Hydro assembly was conducted in 1957. With the termination of the Rover Program in 1973, TA-18 was downsized and reorganized and work shifted to mock-ups of a plasma-core power reactor, which used fuel elements and beryllium, enriched uranium foils, and uranium hexafluoride gas. Criticality work involving reactor safety, and later, nuclear detection technologies continued under various other groups. During the 1970s and 1980s, additional buildings were added. Presently termed the LACEF, work continues in nuclear criticality research nuclear weapons safeguards and security, and treaty verification technology. In 1979, 20 grams of UF6 were released from Building 23 at TA-18. 

1943 Still active EU, U-233, Pu-239; Pu-240 

polonium MFP, I-131 

0.1-10

: 

metal. RuptureNeutronBetatrouranium year lat1954 un4.5%; a98.1% 

TA-19, East Gate Laboratory: Released to AEC in 1962. Early 1940s 1962 None None 

TA-20, Sandia Canyon Site: Former World War II testing and firing area for 

weapon initiators. TA-20 was located within present-day TA-72. TA-20 was 

decontaminated, decommissioned, and abandoned in 1957. 

Early 1940s 1957 DU 

33 of 117 
SEC-00051 02-01-07 

Table 5-1: LANL Technical Areas, Operational Dates, and Radionuclides 

Location Start Demolished or Decomm. Radionuclides 

TA-21, DP Site a.k.a. DP Mesa (General): Former plutonium operations (DP 

West); uranium/polonium operations (DP East); Material Disposal Areas A, B, T, U, V; Tritium Systems Test Assembly, Tritium Science and Fabrication Facility (1945 to 1978). TA-21 was conceived of, and built, during the spring and summer of 1945 for chemical and metallurgical work. The site, as it was developed and used over the years, can be divided into two main sections: DP East and DP West. DP East activities primarily consisted of tritium research. DP West activities primarily included inorganic and biochemistry research. In 

1977, a transfer of work to the new plutonium facility (TA-55) began and much of the complex was vacated. TA-21 was partially decommissioned and decontaminated in 1977-1980. As of 1993, most of the contaminated buildings, exterior duct work, and underground structures still remained at the site 

1945 1977-80 See TA-21 entries below. 

In late 1980s, Cs-137 and U-234 detected in sediments in inactive waste water treatment system outfall; MFP identified in 1979 stack emissions. 

TA-21, DP West, Plutonium facility 1945 NCD WGPu TA-21 DP West >1945 NCD Pu-238, Pu-239, Pu-240, 

Am-241, Pu-241 

0.1-10μ metal. 

TA-21, CMR, Heat sources >1945 NCD Pu-238 AccideTA-21-2 and TA-21-3, Wet Chemistry >1945 1982 Pu 1958 ac

tank, un

TA-21-3, Oxalate precipitation operations >1945 NCD Pu-239, Pu-238, EU TA-21-4 and TA-21-5, Dry chemistry >1945 1981 Pu 

TA-21-4 1945 1948 EU hydride TA-21-4 1960 NCD Pu-239 Hot cel

elemen

TA-21-5, Pu fabrication >1945 Limited use in 

1975 

Pu-239, Pu-238 Fire con

TA-21-12, Filter building >1945 1975 Pu Contam

TA-21-35 and TA-21-257, Liquid Waste Reprocessing Late 1940s 1986 All Pu and 

TA-21-150, Pu fuels development, heat sources development 1963 NCD Pu-238, Pu-239 Sealed 

Oct 197

TA-21-151 and TA-21-152, Experimental program 1945 1984 Po-210, Ac-227 Initiato

34 of 117 
SEC-00051 02-01-07 

Table 5-1: LANL Technical Areas, Operational Dates, and Radionuclides 

Location Start Demolished or Decomm. Radionuclides 

TA-21-153 1945 In service until 

1970-1973 

Po-210, Ac-227 Initiato

TA-21-155, Tritium Systems Test Assembly (TSTA), deuterium and tritium fuels. 1984 1990 HT, HTO >10 bi

Ci relea

TA-21-155 1949 NCD Po-210, Ac-227 Initiato

TA-21-155, DP East, TSTA Tritium Test Assembly Facility, and TA-21-209, Salt Laboratory 

>1945 NCD H-3 Labeled 

HT 

TA-21-210, Pu research >1945 NCD Plutonium 

TA-22, TD (Trap Door) Site: Late in 1944, four buildings were constructed to 

assemble the conventional explosives for the Fat Man weapon. In 1948, the 

buildings were remodeled into office, laboratory, and fabrication space to replace those activities at TA-6. New magazines were also built. In early 1980s, a new Detonation Systems Laboratory was constructed and occupied in 1985 when the older buildings were demolished or abandoned. 

1944 NCD DU Detona

TA-23, NU Site: Nu Site was established for X-Division during 1943 and 1944 

for explosives testing. TA-23 is described as primarily a firing site with two laboratories and a magazine. Post-war activities resulted in contamination with HE, beryllium, radionuclides (e.g., U-238). Nu Site was decommissioned during 1949 and 1950 in preparation for the construction of New Anchor East, at which time it was incorporated into TA-9 for administrative purposes. 

1945 1950 U-238 Firing s

TA-24, T Site: X-ray studies of explosives; later incorporated with TA-16. T 

Site was constructed in the fall of 1944 as a service area for X-ray examination of high explosive charges. A year later, a large storage magazine was constructed. In 1946, a fire damaged the main laboratory building; it was rebuilt in the spring of 1947. Facilities at TA-16 are believed to have once been TA-24 facilities. 

1944 Currently nonoperational DU Faciliti

X-rays 

TA-25, V Site: Explosives assembly; later incorporated with TA-16. V Site, 

with its two main buildings, was constructed in 1944 for experimental work in connection with special assemblies. In 1945, the work was transferred to TDSite (TA-22) and the site underwent extensive alterations permit S-Site process work on explosive charges. In July 1945, V-Site was taken over by SSite. 

1944 Currently nonoperational DU Taken o

35 of 117 
SEC-00051 02-01-07 

Table 5-1: LANL Technical Areas, Operational Dates, and Radionuclides 

Location Start Demolished or Decomm. Radionuclides 

TA-26, D Site: Storage vault and guard building 1946-48; removed in 1966. D-Site was constructed in the summer of 1946 and consisted of a concrete storage vault and a small sentry building and guard tower. 

1946 1966 EU, U-238, H-3, U-233 Storage 

TA-27, Gamma Site (Far Point): Plutonium gun assembly 1945-47. Site active 

from 1944 to late 1946/early 1947. This firing site was an extension of Pajarito Site (TA-18), and during that time (1944-1945), it was called Far Point (not to be confused with Far [Detonation] Point at TA-9). The entire site was abandoned and fenced off in early 1947. Gravel for road material was excavated from lower Pajarito Canyon between 1949 and 1962 along the length of Pajarito Canyon east of TA-18 and within TA-27. During the 1960s, all structure, foundations, and other debris were removed and the ground surface leveled. In March 1960, the area of Gamma Site was reopened to begin construction of a road to White Rock. The road was widened, paved, and opened to the public as Pajarito Road on July 11, 1962. The last major site activity occurred in 1969, when sanitary sewage lagoons and a sever line from TA-18 were built. The lagoons and sever line were the subject of VCA and EC activities in 1995. The former TA-27 is presently located within the fragment impact circle of Firing Site 12 and TA-36 and is potentially affected by operations there. 

1945 1947 Pu-239 

DU, thorium 

Pu gun 

TA-28, Magazine A: Firing site 1979; explosives storage area. 1979 Still active DU Firing sTA-29, Magazine B: Explosives storage area; abandoned in 1957. Early 1940s 1957 DU Explosi

TA-30, Electronics Test Area: Electronics testing. 1945 1948 Unknown 

TA-31, East Receiving Yard: Warehouses west of airport. 1948 1954 Unknown 

TA-32, Medical Research Laboratory: Bio-research facility; 1943-54; removed 

in 1954; incinerator use included. TA-32, known as the Rat Lab, was a small area located behind the Zia Company’s Supply Division Building. Most studies performed here were on internal metabolism of radionuclides, which would have required using low concentrations of radioactive materials. 

1943 1954 Radio-labeling 

compounds, including I131, C-14, S-35, H-3, N15, P-32 Pu-238 (Wingfield, 1974) 

36 of 117 
SEC-00051 02-01-07 

Table 5-1: LANL Technical Areas, Operational Dates, and Radionuclides 

Location Start Demolished or Decomm. Radionuclides 

TA-33, HP (Hot Point) Site: Consists of five sites: Main Site, South Site, East 

Site, Area 6, and the National Radio Astronomy Observatory (NRAO) Site. Established in 1947 as a substitute test site for weapon components experiments being conducted at Trinity Site. Experiments involved testing of beryllium-containing initiators. Many experiments used uranium components. Polonium-210 was used as the radioactive source. Experiments performed in underground chambers (1948-56 shaft experiments), on surface firing pads, and firing sites. These activities cease in 1972. High Pressure Tritium Laboratory operated at Main Site from 1955 until late 1990. Research at TA33 released the largest amount of airborne tritium from routine LASL operations. Releases in 1978 were considerably higher than previous years. From 1973 to 1977, the average routine release of tritium gas from TA-33 was 3050 Ci (range 615 to 5916 Ci). Material Disposal Areas (MDAs) D, E, K. 

1947 1980s late H-3 

U-238, U-236, Po-210, Pu, EU, Pu-239/240 (drum storage stain) 

HTO, H

TA-34, New Laboratory Warehouse Area canceled NA None 

TA-35, Ten Site (General): Radioactive lanthanum 1951-63; Los Alamos Power Reactor Experiment (LAPRE) I/II 1950s; Los Alamos Molten Plutonium Reactor Experiment (LAMPRE) I 1960s; laser fusion research 1974. This site is divided into five facility management units. Work includes nuclear safeguards research and development concerned with techniques for nondestructive detection, identification, and analysis of fissionable isotopes. Research is also done on reactor safety, laser fusion, optical sciences, pulsedpower systems, high-energy physics, tritium fabrication, metallurgy, ceramic technology, and chemical plating. Major decommissioning activities were completed in 1981, including LAMPRE I, a titanium-contaminated laboratory, and removal of contaminated air scrubbers from TA-35-7 (DOE/EIS-0238). 

See TA-35 entries below. 

TA-35, CMR-10 1950 1963 La-140, Ba-140 

Po-210 

Sr-90 c

TA-35, LAMPRE 1955 1967 MFP, Sr-90, Co-60, VFP, 

MAP, Np-237, Pu 

Molten 

TA-35, LAPRE I, LAPRE II test reactors 1955 1960 MFP, Sr-90, Co-60, VFP, 

MAP 

Highly 

TA-35, Laser Fusion Research 1974 NCD unknown TA-35, Target Fabrication Facility (TFF), TSL-213 NCD NCD H-3 Labeled 

37 of 117 
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Table 5-1: LANL Technical Areas, Operational Dates, and Radionuclides 

Location Start Demolished or Decomm. Radionuclides 

HT 

TA-36, Kappa Site: Replaced TA-9, TA-23, and TA-12 in 1950; five active 

firing sites (Eenie, Meenie, Minie, Lower Slobovia, and IJ, and a storage magazine at Moe; non-nuclear ordnance and armor. In 1983, boundary of TA36 changed to incorporate I-J Site (formerly part of TA-15) which was used for firing non-nuclear explosive shots up to 500 lb. TA-36 also includes former TA-27 and part of TA-54 (located north of TA-18). Lower Slobovia also contains a firing site debris pit. 

1950 Still active DU 

TA-37, Magazine Area C: Explosives storage area. NCD Still active DU 

TA-38, Monterey Site (canceled) NCD NCD None 

TA-39, Anchor Canyon Site: Operated by the Shockwave Physics Group; 

consists of five firing points, several gun sites, a waste disposal pit, Material Disposal Area Y; incinerator 1955-60; photographic study of the behavior of non-nuclear weapons. In the later 1980s, U-235 was detected in soil samples taken from the TA-39 landfill used to dispose of firing site debris. 

NCD NCD NU, DU, thorium, EU, Pu Firing p

TA-40, Detonator Firing (DF) Site: Built in 1950 to replace the detonator firing 

chambers at TA-6. Contains six firing points used since 1950 for explosives testing related to research and development of detonators and other small explosives assemblies. TA-40 includes an inert assembly building, six firing chambers, five shot 

preparations buildings, eight magazines. In the 1980s, one 

firing chamber was upgraded to house a two-stage gas gun. First contained test-firing site completed in 1992. Scrap Detonation Site (SDS) consists of detonation area, a burn pit, and three small burn areas operated as RCRA interim status hazardous waste thermal treatment unit for open burning and open detonation of explosive scrap until 1985. 

1950 1985 H-3, U 

TA-41, W (Weapons Group WX) Site: Engineering of nuclear components; 

fabrication of test materials. 

NCD NCD H-3, Pu, U, Am-241 Engine

Fabrica

TA-41-4, Ice House NCD NCD H-3 HTO, H

TA-42, Incinerator Site: Reduced low-level Pu-contaminated waste; abandoned 

in 1970; decommissioning began 1978. 

NCD 1978 All Reduce

38 of 117 
SEC-00051 02-01-07 

Table 5-1: LANL Technical Areas, Operational Dates, and Radionuclides 

Location Start Demolished or Decomm. Radionuclides 

TA-43, Health Research Laboratory (HRL): Biological research 1953-70; replaced 

TA-32. 

1953 1970 I-125 

H-3 C-14 P-32 All others possible 

Iodide, Labeled HT Labeled Labeled 

TA-45, Radioactive Liquid Waste Treatment Plant, WD Site; removed majority of 

plutonium before discharge to Acid Canyon. 

1951 1960 

1964-operations ended 1966– decomm. 

All MFP, Pu-238, Pu-239, EU, U-238 

Remov

TA-46, WA Site: Rover batteries. 1950 1974 EU, U-238, Th 

TA-46, WA Site: U isotope separation; photochemistry research; lasers. 1976 1980s EU, U-238, Th 

TA-48, Radiochemistry Site: Actinide chemistry and hot cell isotope production. 

The radiochemistry building, built to house radiochemistry and nuclear 

medicine research, was constructed in 1957 when stack emissions are believed to have begun. Initial activities involved study of nuclear bomb test samples 

and evolved to include other weapons testing studies, radioactive materials 

waste disposal studies, basic radiochemistry research, and production of radioisotopes for nuclear medicine. 

1950s Still active All , MAP, MFP, U, TRU 

TA-48, Nuclear Chemistry 1950s Still active Se-75 

H-3 Cd-109 I-131 

Spallatitargets HTO, HCL/NO

phosphvery soFission 

39 of 117 
SEC-00051 02-01-07 

Table 5-1: LANL Technical Areas, Operational Dates, and Radionuclides 

Location Start Demolished or Decomm. Radionuclides 

TA-49, Frijoles Mesa Site: Underground hydro-nuclear experiments 1960-61. A 

small radiochemistry facility was built at the site to support the experiments. Most above-ground structures have been removed and the surface has been decommissioned and decontaminated. The site is now used for Hazardous Devices Team Training. 

1960 1961 H-3, Pu, U, EU, Pu-238, 

Pu-239, Pu-240, Am-241, Cs-137 

TA-50, Waste Management Site: Treated liquid wastes before discharge to 

Mortandad Canyon; replaced TA-45, -35; controlled air incinerator 1976. 

1963 NCD Pu-238, Pu-239, Pu-240 

All, including U, EU, Pu238, Pu-239, Pu-240, Sr90, Sr-88, Am-241, Cs137, Mn-54, Co-56, Co58, Co-60, Zn-65, Se-75, 

Y-88, La-140, Rb-83, Ba133 

0.1-10

: 

metal. 

TA-51, Environmental Research Facility: Animal exposure facility 1962; now 

studies of impact of waste and waste storage on the environment. 

1962 Still active Co-60, Sr-90 Animal 

Present

TA-52, Reactor Development Site: Ultra-High Temperature Reactor Experiment 

(UHTREX) 

Late 1960s 1970 U-238, Pu-238, H-3, VFP, 

Kr, Xe, EU 

High-teUHTREExperim

TA-53, Los Alamos Neutron Science Center (LANSCE): Largest accelerator facility, LAMPF. I n the late 1980s, a number of radionuclides were found in the sludge 

in the TA-53 Wastewater Treatment Lagoon that received discharges from the machine shop at TA-5. 

1972 NCD O-15, Ar-41 

C-11 N-13 I-131 Induced activity in U targets, corrosion products H-3 Be-7 

Short-liShort-liLANSCShort-libeam cMedica2A metoccurs seen whmainten

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Table 5-1: LANL Technical Areas, Operational Dates, and Radionuclides 

Location Start Demolished or Decomm. Radionuclides 

TA-53, Currently active solid waste disposal area; Materials Disposal Areas G, 

H (inactive), J, and L. MDA G is the LLW disposal area for the Laboratory and has been in use since 1957. It has also been used to store low-level TRU mixed waste, as well as liquid hazardous and mixed wastes. Three fires occurred at MDA G between 1960 and 1976. On 09/16/60, most of the exposed waste in Pit 1 burned before the fire was discovered. A fire in Pit 3 on 11/21/64 burned boxes and resulted in detectable alpha activity in the smoke. On 04/14/76, a fire in Pit 24 burned for several seconds with no detectable contamination. MDA H was used from 1960 until 1986 to dispose of classified waste, including but not limited to: weapon components, DU scraps, graphite nuclear reactor fuel elements, radioactive sources, detonators, solid radioactive waste tritium, and plutonium-contaminated shapes and records. Eight of the nine shafts at MDA H are sealed and one shaft received waste as late as 1986. The original closing plan for Shaft Nine was submitted in November 1986. Tritium migrated from the shafts at MDA H in the 1960s and early 1970s. Air samples collected from shafts at MDA H had elevated tritium activity of “1.6 to 4.4 million times the DOE derived concentration guide of 1.0 x 103”. 

Subsequent investigations show that tritium has been released from MDA H shafts to the surrounding turf where it may be released by evaporation or transpiration from plants. MDA J began receiving administratively-controlled waste in 1961. Other residual amounts of non-nuclear hazardous waste were also received in the early years. The non-destructive testing (NDT) program, which supports verification and certification of TRU wastes, is conducted at MDA L. 

1957 Still active All, including TRU, H-3, 

DU Pu-238, Pu-239, Pu-240, 0.1-10

: 

metal. 

TA-55, Plutonium Facility (PF-4): Established in 1973 for operation of the 

Plutonium Processing Facility. Operations include fabrication of plutonium metal components, plutonium processing, and basic research of TRU materials. Replaced TA-21; SNM storage 1978 to present. 

1973 Still active H-3 

Pu-238, Pu-239, Pu-240 

Labeled HT 0.1-10

: 

metal. 

TA-56, Subterranean Basalt Site: Melting basalt with electrically-heated 

penetrator; abandoned in 1976. 

NCD 1976 Unknown 

TA-57, Fenton Hill Site: Hot Dry Rock geothermal project. 1978 Inactive Unknown 

TA-58, Two-Mile Mesa North Site: Undeveloped and reserved for multi-use 

experimental sciences for TA-3 programs. 

NCD 1989 Unknown 

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Table 5-1: LANL Technical Areas, Operational Dates, and Radionuclides 

Location Start Demolished or Decomm. Radionuclides 

TA-59, Occupational Health Site: Office of Environment, Safety, and Health 

offices, emergency management. Over the years, groups at TA-59 included industrial hygiene, environmental surveillance, epidemiology, health, environmental chemistry, and meteorology. A septic system, container storage area, and sump were investigated for radionuclides and chemicals and recommended for NFA. 

NCD NCD All sources 

TA-60, Sigma Mesa: Test Fabrication Facility and Rack Assembly; Alignment 

Complex. 

NCD NCD Unknown 

TA-61, East Jemez Road: Physical support and sanitary landfill. NCD NCD Unknown 

TA-62, Northwest Site: Reserved for experiments, research, buffer zones. 

Used for detonator development activities for most of the history of the Laboratory. 

NCD NCD Unknown 

TA-63, Pajarito Service Area: Environmental and waste management 

functions. 

NCD NCD Unknown 

TA-64, Central Guard Facility, Hazardous Materials Response Team. NCD NCD None TA-65, This undeveloped TA was incorporated into TA-51 and no longer 

exists. 

Undeveloped NA None 

TA-66, Central Technical Support Site: Industrial partnership activities. NCD NCD U-238 identified in 1977 

stack emissions. 

TA-67, Pajarito Mesa: A buffer zone, designated as a technical area in 1989. 

Includes the location of the former TA-12 (also known as L Site), which was used from the 1940s to the mid-1950s as a firing site and dynamic testing area; area contains significant archeological sites. 

1989 Active buffer 

zone 

DU 

TA-68, Water Canyon Site: Dynamic testing area with study areas. NCD NCD DU 

TA-69, Anchor North Site: Created in 1989. Incorporates a number of small 

structures (i.e., guard station, trailers for office space, incinerator building). 

Before 1989, structures designated with either TA-0 or TA-6 numbers. Incinerator (TA-69-3) built in 1959 and used until late 1970s to destroy classified documents. Currently environmental buffer for the dynamic testing area. 

1989 Active buffer 

zone 

Unknown 

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Table 5-1: LANL Technical Areas, Operational Dates, and Radionuclides 

Location Start Demolished or Decomm. Radionuclides 

TA-70, Rio Grande Site: Undeveloped; buffer for the high-explosives test area. 

Never used for any Laboratory operations 

1989 Active buffer 

zone 

Unknown 

TA-71, Southeast Site: Undeveloped; buffer for the high-explosives test area. 

TA-71 has never been used by the Laboratory to conduct any experiment. 

NCD Active buffer 

zone 

Unknown 

TA-72, East Entry Site: Protective Forces Training Facility. Former site of 

TA-20 

NCD NCD Unknown 

TA-73, Los Alamos Airport: On-site disposal area; incinerator 1950s. NCD NCD All TA-74, Otowi Tract: Large undeveloped area. Contains Laboratory water wells 

and future well fields, significant number of archeological sites and an endangered species breeding area. 

NCD NCD None 

Pacific Proving Grounds, Nuclear tests: Marshall Islands (1945-51). 1945 1951 All AK, Nuclear tests: Amchitka (Long Shot, Milrow, Cannikin) 1965, 1969, 

1971. 

1965 1971 All 

NV, Nuclear tests, non-NTS: Fallon (Shoal); Tonopah (Faultless) 1968. NCD NCD All 

CO, Nuclear tests: Grand Valley (Rulison) 1970; Rifle (Rio Blanco) 1973. 1970 1973 All, esp. H-3, Kr-85 NM, Nuclear tests: White Sands (Trinity) 1945; Carlsbad (Gnome) 1961; 

Farmington (Gasbuggy) 1967. 

1945 1967 All, esp. I-131, I-133, 

I-135, Cs-137, Ba-140, La-140, heavy elements 

MS, Nuclear tests: Hattiesburg (Salmon and Sterling). NCD NCD Unknown 

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5.3 Radiological Exposure Sources from LANL Operations 

This section discusses the sources of potential radiological exposure present at LANL during the 

period under evaluation. These sources include alpha and beta emissions, neutrons, and photons, as 

well as a variety of incidents and accidents. 

5.3.1 Alpha Particle Emissions 

Many of the primary radioactive source materials handled at LANL were alpha particle emitters. 

Although alpha particles do not present an external exposure hazard, prevention of internal exposures 

to alpha emitters was recognized from the onset of site operations as the most significant radiological 

hazard protection challenge. The primary alpha-emitting radionuclides of concern were: weaponsgrade plutonium (i.e., Pu-239, Pu-240); Po-210; and uranium in varying isotopic abundances of 

U-234, U-235, and U-238. Lesser quantities of Pu-238, Am-241, Th-232 (plus decay progeny), 

Ra-226 (plus decay progeny), U-233, and Cm-244 were used in various projects or as sources. Table 

5-2 provides a summary of the characteristic alpha emission energy for each of these radionuclides. 

Table 5-2: Alpha Particle Energies For LANL Alpha-Emitting Radionuclides 

Radionuclide Alpha Energy (MeV) 

Pu-239 5.16, 5.11 

Pu-240 5.17, 5.12 

Po-210 5.31 

U-234 4.72, 4.77 

U-235 4.37, 4.40, 4.58 

U-238 4.15, 4.20 

Pu-238 5.50, 5.46 

Am-241 5.49, 5.44 

Th-232/(progeny) 3.95, 4.01/(5.34 to 8.78) 

Ra-226/(progeny) 4.60, 4.78/(3.72 to 7.69) 

U-233 4.82, 4.78 

Cm-244 5.90 

Th-230 4.68, 4.62 

Pa-231 4.95, 5.01, 5.02 

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5.3.2 Beta Particle Emissions 

The diverse activities conducted within LANL facilities during the period under evaluation involved 

an extensive beta particle-emitting source term. Historically, beta radiation over a broad range of 

energies would have been encountered from: certain plutonium isotopes; uranium progeny; thorium 

progeny; tritium; radioactive lanthanum (residual Sr-90 after 1963 is the only RaLa program-related 

contaminant addressed in this evaluation); activation and fission products from reactor and accelerator 

operations; and other radionuclides used in biomedical research or as calibration sources. Whether a 

beta source is considered an internal hazard or both an internal and external hazard depends on the 

maximum energy of the beta emission continuum for a given radionuclide, the shielding employed, 

and the use of protective clothing. In many cases, beta-emitting radionuclides also emit characteristic 

photons, as discussed in Section 5.3.4. 

The emissions from low-energy beta emitters such as tritium (0.0186 MeV βmax) do not penetrate the 

outer dead skin layer and are, therefore, not considered as external hazards; however, they may 

present an internal hazard. Higher-energy beta emitters present both an external hazard (to the skin) 

and an internal hazard. Table 5-3 is not an all-inclusive list, but it provides a summary of the more 

prevalent beta-emitting radionuclides over a range of energies and segregated by process. 

Table 5-3: Beta Particle Energies For LANL Beta-Emitting Radionuclides 

Radionuclide Beta Maximum Energy (MeV) 

Weapons-related radionuclides: 

H-3 0.019 

Pu-241 0.021 

U-238 Progeny (Th-234, Pa-234m) 0.193, 2.29 

U-235 Progeny (Th-231) 0.305 

Ac-227 0.046 

Sr-90/Y-90 2.27 

Reactor/Accelerator-related (Mixed Fission and Activation Products) radionuclides: 

Cs-137 0.514 

Co-60 0.314 

I-131 0.606 

Chemistry/metallurgy/miscellaneous radionuclides: 

Th-232/progeny 0.055 to 2.26 

Ra-226/progeny 0.016 to 3.26 

S-35 0.167 

C-14 0.156 

P-32 1.710 

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5.3.3 Neutron Exposures 

There were numerous potential neutron exposure sources associated with essentially all of the 

predominant LANL operations. Neutron exposures could have resulted from plutonium chemical and 

metallurgical operations, neutron-generating sources, criticality experiments, and operating reactors 

and accelerators. The source of the neutron emissions from these activities and potential worker 

exposure would have been associated with the following: 

•	 Spontaneous fission of Pu-240 (as an impurity in the weapons-grade plutonium). 

•	 Alpha-neutron (α,n) reactions with low-atomic-number elements associated with plutonium 

chemical processing (PuF4 and PuO2) and, to a lesser extent, plutonium in metallic form. 

•	 Fission neutrons from operating reactors and from criticality assembly experiments using 

plutonium or enriched-uranium spheres. 

•	 Accelerator-produced neutrons. 

•	 Neutron-generating sources either via the α,n reaction (PuBe, RaBe, PoBe) or via spontaneous 

fission sources (Cf-252). 

The broad scope of the LANL neutron-generating activities resulted in a correspondingly extensive 

neutron energy spectrum. The spectrum ranged from the thermal energy region of 0.025 eV through 

the fission spectrum of 0.1 to 6.0 MeV (predominant energy of 0.7 to 1.0 MeV), and included 

high-energy, accelerator-produced neutrons up to 20 MeV. Table 5-4 provides the default neutron 

energy spectrum associated with the multiple LANL operations. 

Table 5-4: Default Neutron Dose Fractions for LANL Materials 

Operation 

Neutron Dose Fraction Percentages by Neutron Energy 

<10 to 100 keV 0.1 to 2 MeV 2 to 20 MeV 

Plutonium Production 11% 56% 33% 

Operating Reactors 0% 100% 0% 

Accelerators 60% 20% 20% 

Criticality Experiments 3.2 % 59% 38% 

Chemistry and Metallurgy 10% 50% 40% 

Neutron Sources 0% 100%* 0% 

* Note: This dose fraction is not included in ORAUT-TKBS-0010-6; it is the author’s interpretation of neutron energy 

distribution from the spontaneous fission of Cf-252. 

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5.3.4 Photon Exposures 

As with neutron exposures, many LANL radiological operations, including waste handling, also 

involved gamma and X-ray photon radiation fields. Potential photon exposure sources to workers 

would have been associated with the following: 

•	 Gamma-emitting fission and activation products resulting from reactor operations or 

accelerator-produced air or target activation products. 

•	 Uranium compounds and associated decay progeny. 

•	 Bremsstrahlung radiation. 

•	 X-ray-generating machines. 

•	 Aged weapons-grade plutonium work. 

•	 Work with, or calibration sources of, americium, thorium, radium, cobalt, and other miscellaneous 

radionuclides. 

Table 5-5 summarizes default photon energies for LANL materials. 

Table 5-5: Default Photon Energies for LANL Operations 

Operation 

Gamma Energy Distribution Percentage 

< 30 keV 30 to 250 keV > 250 keV 

Plutonium Processing and Production 65% 35% 0% 

Uranium Production 0% 100% 0% 

Reactors 0% 25% 75% 

Accelerators 0% 5% 95% 

X-Ray Generating/Radiography 0% 50%* 50%* 

Waste Handling 0% 50% 50% 

Calibration Sources 0% 25% 75% 

* Note: This energy distribution is not included in ORAUT-TKBS-0010-6; it is the author’s interpretation of photon 

energy distribution from Co-60, Cs-137, Ir-192 radiography sources, and portable 150 and 220 keV portable X-ray 

machines located in TA-16. 

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5.3.5 Incidents and Accidents 

Numerous documented major incidents and accidents occurred at LANL during the evaluated time 

period. The major recorded incidents and accidents are summarized in the Technical Basis Document 

for Los Alamos National Laboratory – Site Description (ORAUT-TKBS-0010-2). Of the 54 

accidents/incidents described, 40 occurred between 1943 and 1975. Four of these were 

non-radiological accidents involving explosives or fires. The remaining radiological 

incidents/accidents included 14 unplanned criticalities; three resulted in fatalities and overexposures, 

three resulted in overexposures, and eight did not involve known personnel exposures. The following 

is a brief chronological description of documented LANL criticalities (LANL, 2000). 

1. February 11, 1945: Dragon assembly; UH-3 pressed in styrex; single excursion; insignificant 

exposures. The Dragon assembly was the first fissile system designed to generate prompt 

power excursions and was probably the first reactor of any kind whose reactivity exceeded 

prompt criticality. The Dragon was made of enriched UH-3. During the final excursion of 

about 6E15 fissions, the UH-3 cubes became so hot that blistering and swelling occurred. The 

whole system expanded about 1/8-inch. In the final excursion, the core material was damaged, 

but no active material was lost; there was no contamination and no one received any radiation. 

2. June 6, 1945: Pseudosphere of uranium cubes; water-reflected; single excursion; three 

significant exposures. This experiment, designed before the days of remote control, was 

intended to establish the critical mass of enriched uranium metal surrounded by hydrogenous 

material. The uranium mass of 35.4 kg (average enrichment 79.2%) was stacked in the form 

of a pseudosphere constructed of 1⁄2-inch cubes and 1⁄2-inch x 1⁄2-inch x 1-inch blocks. The 

whole assembly was placed in a large tank that was then partially filled with water. 

Unexpectedly, the assembly became critical before water had completely covered the 

polyethylene box. The situation was aggravated because no scram device was built into the 

system and the inlet and drain valves were 15 feet apart. Before the system was reduced to a 

safely-subcritical state five or ten seconds later, a total of 3 to 4E16 fissions occurred. In this 

excursion, three people received radiation doses in the amounts of 66, 66, and 7.4 rep. 

3. August 21, 1945: Plutonium core reflected with tungsten carbide; single excursion; one 

fatality, one significant exposure. A critical assembly was being created by hand-stacking 4.4 

kilogram (kg) of tungsten carbide bricks around the plutonium core. The lone experimenter 

was moving the final brick over the assembly for a total reflector of 236 kg when he noticed 

from the nearby neutron counters that the addition of this brick would make the assembly 

supercritical. As he withdrew his hand, the brick slipped and fell onto the center of the 

assembly, adding sufficient reflection to make the system superprompt critical. A power 

excursion occurred. He quickly pushed off the final brick and proceeded to unstack the 

assembly. His dose was estimated as 510 rem from a yield of 1E16 fissions. He died 28 days 

later. An Army guard assigned to the building, but not helping with the experiment, received a 

radiation dose of approximately 50 rem. 

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4. May 21, 1946: Plutonium core reflected with beryllium; one fatality, seven significant 

exposures. The techniques involved in creating a metal critical assembly were being 

demonstrated to several people. The system consisted of the same plutonium sphere discussed 

in Item 3 above, reflected in this case by beryllium. The top and final hemispherical beryllium 

shell was being slowly lowered into place; one edge was touching the lower beryllium 

hemisphere while the edge 180° away was resting on the tip of a screwdriver. The person 

conducting the demonstration was holding the top shell with his left thumb placed in an 

opening at the polar point. The yield of this excursion was 3Ε15 fissions. The eight people in 

the room received doses of about 2100, 360, 250, 160, 110, 65, 47, and 37 rem. The man who 

performed the experiment died nine days later. 

5. December 1949: Water boiler reactor; control rods removed by hand; single excursion; 

insignificant exposure. This accident occurred when two new control rods (poisons) were 

being tested in the water boiler reactor. The water boiler was a 12-inch diameter stainless steel 

sphere containing 13.6 liters of uranyl nitrate reflected by thick graphite. The rods had been 

installed and the operator was manually checking their drop times. After several tests of each 

individual rod (a safe procedure since one rod was sufficient to maintain subcriticality), both 

rods were pulled, held for about five seconds, and then dropped simultaneously. A short time 

later, the rods were again pulled and dropped together. The removal of the two rods increased 

the reactivity over prompt criticality, corresponding to a period of 0.16 seconds. The power 

probably rose within this period to a very broad peak of 2 or 3E16 fissions/sec and remained 

close to this value for about 1.5 seconds. The excursion was not immediately detected because 

all the instruments were turned off except for a direct reading thermometer that showed a 

temperature rise of 25C, equivalent to a yield of 3 or 4E16 fissions. The operator received a 

2.5 rad dose. 

6 & 7. February 1, 1951: Critical separation experiment; two large 235-U metal masses in water; 

multiple excursions; insignificant exposures. A water-reflected system was set up in 1949 to 

obtain the neutron multiplication of a single unit of fissile metal in water. The system had two 

scram devices. The excursion was precipitated by an experiment that measured the critical 

separation distance of two enriched uranium masses (each of 93.5% U-235) in water: one a 

solid cylinder of 24.4 kg, and the other a hollow cylinder of 38.5 kg. At the completion of the 

critical separation experiment (at a multiplication of 65.5), the assembly was scrammed. The 

water started draining, the cadmium screen dropped, the solid cylinder was lifting, and an 

excursion (later determined to be 1E17 fissions) was made evident by the jamming of neutron 

counters and the appearance on television of a vapor cloud above the water. Later 

reconstruction of the accident showed that the pneumatic tangential scram was the first to be 

effective and led directly to two types of difficulty. First, the center of reactivity of the lefthand cylinder proved to be below that of the stationary cylinder; second, the rapid lift through 

the water created hydrodynamic forces that swung the cylinders closer together. The 

combination of the two effects was enough to drive the assembly prompt critical and to have 

maintained at least this much reactivity for 0.2 seconds if the power excursion had not 

occurred. The first power spike is estimated to have contained 6E15 fissions. It is possible 

that one or more excursions into the prompt region followed because boiling was the primary 

quenching mechanism. In the excursion of 1E17 fissions, no radiation doses were received, 

and no contamination was found in the experimental area. 

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8. April 18, 1952: Jemima, cylindrical, unreflected 235-U metal assembly; excursion history 

unknown; insignificant exposures. The system in which the excursion took place was an 

acylindrical, unreflected, enriched 93% U-235 metal assembly made up of a number of plates, 

each 267 mm in diameter and 8 mm thick. Complete assembly of the two components had 

been made previously with six plates in the lower component, but with at first three, and then 

four, plates in the upper component. A plot of the reciprocal multiplication versus number of 

plates, or total uranium, shows clearly that the system should not have been assembled with 11 

plates. Nevertheless, such an assembly was attempted following a computational error made 

independently by two people. Contrary to operating regulations, a graph of the data had not 

been plotted. The burst yield was 1.5E16 fissions. The power dropped essentially to zero 

when the automatic scram system separated the two masses of metal. During the remotelycontrolled operation, no damage was done to the system, even to the fissile material. None of 

the personnel received any radiation and the experimental area was not contaminated. 

9. February 3, 1954: Lady Godiva reactor; bare 235-U sphere; control rod incorrectly operated; 

single excursion; insignificant exposure. The Lady Godiva assembly was an unreflected metal 

reactor fabricated in three principal sections that when assembled formed a sphere. The 

critical mass was about 54 kg of uranium enriched to 93.7% U-235. It was operated remotely 

from a distance of 1/4 mile. The first accidental excursion occurred during preparations for a 

scheduled prompt burst, part of a program to measure the parameters associated with 

excursions. This accidental excursion was apparently caused because additional reactivity was 

inserted by error. The excursion yield was 5.6E16 fissions, about six times the yield of the 

average burst. There was no radiation hazard, contamination, personnel exposure to radiation, 

or significant damage to the major uranium parts. One piece was slightly warped and required 

re-machining. 

10. February 12, 1957: Lady Godiva reactor; bare 235-U sphere; added reflection; single 

excursion; insignificant exposures. This accidental excursion occurred during preparations for 

an experiment in which the Lady Godiva reactor (see Item 8 above) was to provide a pulse of 

fast neutrons. As in 1954, the burst occurred during assembly. The extra reactivity is thought 

to have been contributed by a large mass of graphite and polyethylene that was to be 

irradiated. This mass had just been moved close to Godiva, and either the change in reflection 

was underestimated or the material slumped further toward Godiva. The burst yield was 

1.2E17 fissions, about 12 times the standard excursion. The uranium metal was severely 

oxidized, warped, and apparently had been plastic near the center. The central burst rod was 

nearly ruptured and, at its center, must have been within 100o C of the uranium melting 

temperature. External damage was limited to the supporting structure; radioactive 

contamination consisted of oxide scale; clean-up proceeded rapidly. Repair of Lady Godiva 

was not practical; therefore, construction of Godiva II (specifically designed for burst 

operation) was accelerated. Despite the severity of the excursion, operating personnel received 

no significant radiation exposures because of the large distance between the reactor and the 

control room. 

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11.	 July 3, 1956: Honeycomb critical assembly; U(93) metal foils moderated with graphite; single 

excursion; insignificant exposures. The machine in which this excursion occurred consisted of 

a large matrix of 576 square aluminum tubes split down the middle with one-half of the matrix 

moveable on tracks. Generally, the facility had been used to simulate design features of 

complicated reactors because of the versatility in arrangements of uranium foil and various 

moderating materials. The stacking consisted of 58 kg of enriched (93% U-235) uranium in 

the form of 2- and 5-mil foils arranged between slabs of graphite with some beryllium reflector 

surrounding the core. The total mass of graphite was 1,139 kg. At the time, some changes had 

been made in the reflector and graphite moderator, and criticality was being approached too 

rapidly for routine measurements. While the cart was moving at about 0.2 inch per second, the 

system became prompt critical, a burst occurred, and the scram system retracted beryllium 

control rods (reducing reactivity) and reversed the motion of the cart. The burst yield was 

3.2E16 fissions. There was no damage and no contamination. Because it was remotely 

controlled from a distance of 1/4 mile, no one received any radiation. 

12. December 30, 1958: Plutonium organic solution in an organic treatment tank; single 

excursion; one fatality, two significant exposures. The operations performed at the facility 

where the accident occurred were those chemical steps used to purify and concentrate 

plutonium from slag, crucible, and other lean residues that resulted from recovery processes. 

Typical and expected solutions contained less than 0.1 g Pu/ l and traces of americium. An 

annual physical inventory was in progress at the time of the accident; thus, the normal flow of 

process streams into the area was interrupted so that residual materials in all process vessels 

could be evaluated for plutonium content. A reconstruction of significant events indicates that 

unexpected plutonium-rich solids, which should have been handled separately, were washed 

from two vessels into a single large vessel that contained dilute aqueous and organic solutions. 

After most of the aqueous solution had been removed from this vessel, the approximately 200 

liters of material remaining, including nitric acid wash, was transferred to the stainless steel 

tank in which the accident occurred. The tank contained about 295 liters of a caustic stabilized 

aqueous organic emulsion, and the added acid is believed to have separated the liquid phases. 

The aqueous layer (330 liters) is estimated to have contained 60 g of plutonium; the organic 

layer (160 liters) contained 3.1 kg of plutonium. When the stirrer was started, the initial action 

forced solution up the tank wall, displacing the outer portion of the upper layer and thickening 

the central region. The motion changed the system reactivity to superprompt critical, and an 

excursion occurred. The excursion yield was 1.5E17 fissions. The accident resulted in the 

death, 36 hours later, of the operator who was looking into a sight glass when the motor was 

turned on. The dose to his upper torso was estimated to have been 12,000 rem. Two other 

persons apparently suffered no ill effects after receiving radiation doses of 134 and 53 rem. 

No equipment was contaminated or damaged even though the shock associated with off-axis 

bubble generation displaced the tank about 10 mm at its supports. 

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13. June 17, 1960: 235-U metal, graphite-reflected, assembly; single excursion; insignificant 

exposures. The critical parameters of highly-enriched (93% U-235) uranium metal cylinders 

in thick graphite (about 9 inches) and near-infinite water reflectors were being investigated. In 

the experiment of interest, an approximately 48 kg uranium annulus was built up on a cylinder 

of graphite that, in turn, rested on a hydraulic lift device. This annulus was raised by remote 

control into a reflector of graphite resting on a stationary steel platform. The system became 

critical before complete assembly and was scrammed both manually and automatically at 

about one inch from closure. Following the scram signal, the lift dropped rapidly and the 

system became subcritical, but about one–third of the metal mass stuck in the graphite 

reflector for a few seconds before falling to the floor. The yield was 6E16 fissions. There was 

no contamination or damage to the fissile metal and personnel radiation doses were 

immeasurably small. 

14. December 11, 1962: Zepo critical assembly; 235-U foils, graphite moderated; single 

excursion; insignificant exposures. The critical assembly consisted of a large cylindrical 

enriched uranium–graphite core on a lift device and a stationary platform holding a reflector of 

graphite and beryllium into which the core was raised. Most of the U-235 was placed in the 

graphite in the form of thin foils; therefore, the excursion characteristics should be similar to 

those of the honeycomb assembly. The experiment was concerned with measurements of the 

axial fission distribution, which was perturbed from its normal value by an end reflector of 

layers of graphite and polyethylene. For this reason, some fresh U-235 foils had been placed 

in the assembly to obtain a reasonably precise value of the fission energy release. The crew 

assumed the assembly had been run and checked the previous day; however, this was not the 

case. The system became critical with the core in motion upward. The instrumentation 

scrammed the assembly when the power was about 200 watts. Before the lift could coast to a 

stop and start down, the system reactivity exceeded prompt criticality and the yield was 3E16 

fissions. No damage was done and personnel radiation doses were not measurable. The 

laboratory was entered within 30 minutes. 

The remaining accidents/incidents involved contamination incidents, personnel internal or external 

overexposures from radioactive materials or radiation-generating devices, or inadvertent releases of 

effluents with elevated radioactive material concentrations. These events are described in multiple 

historical monthly and annual Health Division reports. In addition, these various group reports 

contain much anecdotal evidence of other small-scale contaminations, radioactive material release 

events, and external/internal exposures occurring that may or may not have been formally recorded 

because the associated levels were less than the limits in effect at the time. The various operational 

reports reviewed described other personnel exposures that did not exceed the protective guides 

applicable at the time and were, therefore, discussed accordingly. 

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6.0 Summary of Available Monitoring Data for the Proposed Class 

The primary sources of information for this evaluation are the LANL Occupational Internal Dose and 

Occupational External Dose TBDs (ORAUT-TKBS-0010-5 and ORAUT-TKBS-0010-6). These 

documents contain: (1) information for dose reconstruction; (2) monitoring data that pertain directly to 

the class under evaluation; (3) the identities and maximum quantities of radionuclides of concern; (4) 

descriptions of the processes through which the radiation exposures of concern may have occurred and 

the physical environment in which they may have occurred; and (5) discussions regarding data 

availability and limitations. Thus, much of the discussion that follows represents summaries of 

information in the TBDs. 

Monitoring data are available from the onset of LANL operations in 1943. Initially, the “Health 

Group” was responsible for establishing health standards; specifically, for safe levels of exposure to 

radiation and to radioactive chemical materials. The Health Group’s primary concern was to protect 

the health of laboratory employees. Until mid-1951, for want of adequate staff, the Group accepted 

help for monitoring radiation-related activities from the Chemistry and Metallurgy Research (CMR) 

staff. Over the years, the Health Group evolved into the Health Division (and its successors, 

Environmental, Safety, and Health [ESH] and Health, Safety, and Environment [HSE] Divisions), 

with multiple subgroups that addressed health physics, medical, (industrial) safety, biomedical 

research, industrial hygiene, industrial waste treatment, and environmental studies. While several 

division and group name changes have occurred since 1943, the generic Health Physics Group has 

existed since 1951. 

The following subsections summarize the numbers and types of monitoring records available that are 

applicable to reconstruction of LANL employee internal and external doses. In addition, general 

monitoring program goals, monitoring frequencies, and programmatic changes are summarized. 

Details regarding the specific analyses used, associated MDAs, biases, and uncertainties are not 

presented in this report but can be found in the internal and external TBDs. 

6.1 LANL Internal Monitoring Data 

The following LANL monitoring produced data that are available and applicable to internal dose 

reconstruction for the class period under evaluation: 

•	 Air Sampling Data: Intermittent data for some radionuclides, or as gross activity, available for 

selected buildings from 1945 through 1971. (Section 6.1.1) 

•	 In Vitro Bioassay Data: Primarily urine samples for select radionuclides, primarily plutonium, 

polonium, uranium and tritium; however, isolated bone, lymph node, blood, and organ autopsy 

samples were also taken. Earliest data available are for urine samples collected in 1944. (Section 

6.1.2) 

•	 In Vivo Analysis Data: Primarily whole-body and chest counts, and to a lesser extent, chest, 

thyroid, liver, and wound counts. Earliest data available are from whole-body counts performed in 

1963. (Section 6.1.3) 

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6.1.1 Air Sampling Data 

Maximum and average airborne contamination levels in buildings with high exposure potential are 

listed in Table 6-1. Airborne concentrations are not available for all years of operation and are 

deficient for fission products and some of the exotic radionuclides. The predominant data identified 

was provided as gross alpha activity, gross beta activity, plutonium, or uranium. Many of the original 

count room records did not specify the type of analysis performed or provide the year of the analysis 

on the laboratory form. Blanks in Table 6-1 indicate that no information was available for that period 

(ORAUT-TKBS-0010-5). Average concentrations are calculated from general air samples as simple 

averages or averages obtained directly from LASL reports. Recently, limited air sampling data for 

fission products and other less-prevalent radionuclides such as curium, thorium, and actinium have 

been located. However, these data are intermittent and not inclusive of all areas. Furthermore, the 

data have not been validated or incorporated into databases and will require significant additional 

evaluation and validation before their usefulness for dose reconstruction can be determined. 

Table 6-1: Summary of Airborne Concentrations from Selected LANL Buildings 

Building Nuclidea,b Yeark 

Maximum airborne 

concentrationc 

(dpm/m3) 

Average airborne 

concentrationc 

(dpm/m3) 

D Alpha 1945 674.0 

D Alpha U 1945 2,564.400 

H Alpha Po 1945 48.00 

DP East Alpha (EU) 1945 2,458.0 68.2 

DP West Alpha 1945 254.0 

D Alpha (Pu) 1945 480.0 151.0 

D Alpha (Pu) 1946 2,590.0 46.86 

DP East Alpha (EU) 1946 147,400.0 (Po) 271.27 

TU Building Alpha 1946 1,958.400 43.400 

DP West Alpha 1946 2,400.0 

TU Building Alpha 1947 515.000 

H Alpha Po 1947 8.80 

Sigma Total alpha U 1947 187.20 

D U 1947 55.00 

D Pu 1947 134.00 

D 

Cold lab 

alpha 1947 15.0 

Sigma U 1948 1,393.80 124.60 

U Pu 1948 379.40 66.67 

H Po 1948 52.80 4.50 

D U 1948 2,564.40 21.23 

D Pu 1948 860.80 11.53 

D 

Cold lab 

alpha 1948 882.4 5.675 

Am Lab Am alpha 1948 6.2 1.6 

Sigma Total alpha U 1948 1,393.80 124.60 

DP West Alpha 1949 1,694.0 

Am Lab Am alpha 1949 18.0 

Press Rm Alpha 1949 198.0 

TU Bldg Furnace Alpha 1949 4,095.0 

Waste Treatment Alpha 1949 13.8 

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Table 6-1: Summary of Airborne Concentrations from Selected LANL Buildings 

Building Nuclidea,b Yeark 

Maximum airborne 

concentrationc 

(dpm/m3) 

Average airborne 

concentrationc 

(dpm/m3) 

Lab 

M Alpha 1949 580.8 84.0 

DP East Polonium 1949 2,344.0 

U Alpha 1949 37.2 

D Pu 1952 2.4 

CMR Pu 1952 1.9 

M U 1952 4.6 

D Pu 1953 600.4 3.2 

CMR Pu 1953 388.7 1.0 

U Pu 1953 4.5 1.4 

M U 1953 210.6 2.4 

Dd U 1953 1,969.3 4.3 

CMR U 1953 21.1 1.2 

CMR Pu 1954 2,851.3 1.3 

CMR Pu 1955 527.2 0.7 

CMR Pu 1956 162.7 0.7 

CMR Pu 1957 351.0 0.8 

CMR Pu 1958 1,370.2 1.0 

CMR Pu 1959 6,712.9 1.0 

CMR Pu 1960 518.1 0.9 

CMR Pu 1961 426.0 1.0 

CMR Pu 1962 4,680.0 1.0 

CMR Pu 1963 166.0 1.0 

CMR Pu 1963 4.0 0.0 

CMR Pu 1967 285.0 1.0 

CMR Pu 1968 5,370.0 1.0 

CMR Pu 1968 11.0 0.0 

CMR Pu 1969 685.0 1.0 

CMR Pu 1969 11.0 0.3 

CMR U 1954 77.4 0.8 

CMR U 1955 112.1 0.7 

CMR U 1956 67.8 1.0 

CMR U 1957 2,231.1 1.4 

CMR U 1958 51.3 1.3 

CMR U 1959 24.0 1.2 

CMR U 1960 94.1 1.2 

CMR U 1961 35.0 1.0 

CMR U 1962 43.0 1.0 

CMR U 1963 65.0 1.0 

CMR U 1963 11.0 0.0 

CMR U 1967 80.0 1.0 

CMR U 1968 53.0 1.0 

CMR U 1968 14.0 0.6 

CMR U 1969 65.0 1.0 

CMR U 1969 258.0 2.4 

Laundry Total alpha 1948 844 450.533 

Laundry Total alpha 1949 2,268 583.067 

Laundry Total alpha 1950 78 42.2857 

TA-21e I-131 1961 1.4E4 NA 

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Table 6-1: Summary of Airborne Concentrations from Selected LANL Buildings 

Building Nuclidea,b Yeark 

Maximum airborne 

concentrationc 

(dpm/m3) 

Average airborne 

concentrationc 

(dpm/m3) 

DP West I-131 1964 302 5.5 

Sigma Beta -gammaf 1947 1.82E+06 

H Beta -gammaf 1947 0.0 

U Beta -gammaf 1947 5.95E+05 

Sigma Beta -gammaf 1948 1.86E+09 8.21E+07 

H Beta -gammaf 1948 3.33E+08 7.39E+07 

U Beta -gammaf 1948 1.47E+09 1.95E+08 

CMR Mixed 

fissionf 1961 78.0 12.8 

CMR Mixed 

fissionf 1962 11,627.0g 19.7g 

CMR Mixed 

fissionf 1963 518.0 15.0 

CMR Mixed 

fissionf 1964 19,256.0h 39.0h 

CMR Mixed 

fissionf 1965 13,404.0i 22.0i 

CMR Mixed 

fissionf 1966 93,887.0j

 366.7j 

CMR Mixed 

fissionf 1967 19,256.0 39.0 

CMR Mixed 

fissionf 1968 13,404.0 22.0 

CMR Mixed 

fissionf 1969 93,887.0 366.7 

CMR Mixed 

fissionf 1970 14,163 

CMR Mixed 

fissionf 1971 18,104 

Notes: 

a. Guidance on adjusting for different enrichments of uranium or mixtures of plutonium is in ORAU TKBS0010-5, Section 5.2. 

b. Information on specific mixtures of fission products is not readily available 

c. Results prior to January 1, 1953 were reported as cpm/L. Listed results have been converted to dpm/m3 

assuming a nominal counting efficiency of 50%. Values shown are as reported by LANL; no estimation of 

the level of precision may be made based on the number of significant figures without the associated 

analytical error. 

d. D Building demolished in 1954. 

e. This information located in Dummer, 1961 

f.	 Mixed Fission Products (assume gross beta/gamma) tolerance is 1 × 10-7 μCi/cc (2.22 × 105 dpm/m3) 

through 1948; MAC is 6.7 × 103

 dpm/m3 from 1961 to 1969. 

g. Highest concentration of 11,627 dpm/m3 is in "uranium cell corridor - no personnel exposure.” Next
 

highest concentration is 207 dpm/m3 . Average concentration would be 11.8 dpm/m3 

. 

h. "No personnel exposure" to highest concentration of 19,256 dpm/m3 . Next highest concentration is 

2,551dpm/m3

. "No personnel exposure" to highest concentration of 13,404 dpm/m3 . Next highest 

concentration is 2,233 dpm/m3 

. 

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i.	 "No personnel exposure" to highest/next highest concentrations of 93,887 and 45,997 dpm/m3 . Next 

highest concentration is 21,553 dpm/m3 

. 

j.	 “No personnel exposure" to highest concentration of 13,404 dpm/m3 . Next highest concentration is 2,233 

dpm/m3 

. 

k. Some additional airborne monitoring data have been located. Research to identify further data is on-going. 

These data have not been validated, compiled, analyzed, or modeled at the time of this report. 

6.1.2 In Vitro Bioassay Sampling Data 

Prior to the 1970s, individual assignments to the bioassay program were determined by the area health 

physics monitors. Until the early 1950s, nasal swipes with alpha activity more than 50 cpm indicated 

the need for follow-up bioassay. Excreta bioassay methods for determining internal exposures were 

developed in late 1944 for Pu and Po; in 1949 for U; and in 1950 for H-3. Starting in 1944, blood 

tests were performed following potential exposures. These blood tests were for blood count levels 

related to external radiation exposure rather than for radioactive content of the blood. Therefore, any 

such blood counts would not be directly applicable to internal dose calculations. The above topics are 

discussed in greater detail in Section 7.2, Internal Radiation Doses at LANL. 

In the 1970s, LANL initiated an Employee Health Physics Checklist. This checklist allowed the 

evaluation of each individual for potential internal and external exposure. Individuals were placed on 

the appropriate monitoring schedule based on this checklist. The checklist is still used and was 

computerized in 1998 as the Dosimetry Enrollment System. 

Table 6-2 summarizes the urinalysis data currently available to NIOSH. In Table 6-2, the following 

applies: 

•	 Results = Number of analytical results available 

•	 People = Number of people monitored 

•	 N/A = Not Available 

•	 Plutonium results were not initially isotope-specific and are based on the plutonium isotopes 

historically present at LANL 

Table 6-3 summarizes the miscellaneous in vitro data available to NIOSH. 

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Table 6-2: LANL Urinalysis Data 

Year 

Am-241a H-3 Po Pu-238 Pu239 U-235/U-238 

results people results people results people results people results people results people 

1944 6 N/A 

1945 347 204 

1946 1069 525 

1947 537 49 1118 468 

1948 473 50 1582 626 

1949 406 55 1621 758 

1950 234 35 328 60 1678 766 1223 112 

1951 824 76 395 105 1863 1041 511 108 

1952 795 92 447 80 1610 816 759 121 

1953 2514 145 951 308 977 613 1222 135 

1954 3132 218 378 57 2031 1026 2852 180 

1955 1579 125 1105 266 2525 1120 2081 204 

1956 1374 126 116 38 2330 1086 1797 230 

1957 1800 104 1 1 2422 1169 1159 174 

1958 1903 161 13 N/A 2177 1057 1033 170 

1959 845 74 2314 1086 1383 200 

1960 379 54 2148 1011 1350 229 

1961 467 57 2025 981 1501 210 

1962 731 91 2098 970 2316 241 

1963 1022 108 1961 975 3578 294 

1964 631 69 2155 1017 3234 342 

1965 841 109 3 N/A 1560 975 3209 284 

1966 936 101 1346 825 3161 279 

1967 852 73 1347 868 3275 253 

1968 685 70 227 98 1319 824 3303 275 

1969 970 101 253 121 1385 841 3096 283 

1970 1549 154 305 142 1457 913 2812 258 

1971 936 86 1265 765 1621 923 2375 269 

1972 946 82 1430 851 1448 860 2341 237 

1973 737 75 1869 1045 1869 1048 1786 204 

1974 828 61 2207 1239 2211 1243 1845 172 

1975 1005 72 2441 1648 2443 1650 1962 164 

Footnote: a

 Some additional Am-241 data have recently been located with the earliest known time period of 1949. Research to identify 

further data is on-going. These data have not been validated, compiled, analyzed, or modeled at the time of this report.
 

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Table 6-3: Miscellaneous LANL In Vitro Monitoring Data 

Year 

Blood Bone Fecala Liver Lung Lymph Nodes 

Po Pu238 

Pu239 Am241 Am241 Po Pu238 Am241 Pu238 Pu239 Am241 Pu238 Pu239 Am241 Pu238 Pu239 

1948 1 

1949 

1950 

1951 

1952 

1953 4 

1954 

1955 6 34 

1956 1 

1957 

1958 

1959 

1960 

1961 

1962 

1963 

1964 

1965 

1966 

1967 

1968 

1969 

1970 

1971 

1972 1 1 1 1 

1973 

1974 

1975 1 2 1 1 1 2 1 1 2 1 1 2 

Notes:
 

Data values = Number of analytical results available. Blood results shown were for analysis of intakes and are not the same as
 

discussed in other sections of this report where blood samples were drawn as indicators of external exposure during the early years 

of LANL operations. Bone, liver, lung, and lymph node are autopsy samples. 

Footnote: a

 Some additional fecal monitoring data have recently been located. The specific radionuclides to which these data apply have not
 

been determined at this time. Research to identify further data is on-going. These data have not been validated, compiled, analyzed, 

or modeled at the time of this report. 

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6.1.3 In Vivo Analytical Data 

In vivo counting equipment and techniques were developed in the late 1950s and have been in routine 

use for measuring X-ray and gamma-ray-emitting radionuclides since 1970 (possibly as early as 

1960). There is some indication that some of the counts recorded between 1955 (program onset) and 

the 1960s were performed for program development rather than actual suspected intakes. NIOSH has 

been unable to locate any records of these early in vivo measurements. 

The first whole-body counter used was the HUMCO I. This “human counter” became operational in 

1955. The counter consisted of a large double cylinder with a liquid scintillation fluid (possibly 

trichloroethylene) filling the annular space between the cylinders. The scintillation fluid was viewed 

with an array of 5-in. photomultiplier tubes on the outside wall of the cylinder. The individual was 

placed inside the count chamber. The count rate was compared to the background count rate. The 

system typically used two energy windows, one for K-40 (1-2 MeV) and one for Cs-137 + K-40 

Compton counts between 0.5 and 0.8 MeV. The result was obtained by subtracting out the 

contribution of K-40. The system was not used for photons below 100 keV. This system was used to 

screen individuals who might have been exposed to fission products at the reactors or in fly-overs 

during weapons testing. It was also used to detect the Bremsstrahlung from Sr-90 intakes. The 

energy resolution of these counters was poor. When an elevation of the background in a region of 

interest was observed, the individual was referred for screening with either the shadow shield or full 

shield 4-in by 8–in. NaI(Tl) crystals (Healy, 1970). The sensitivities of the NaI(Tl) crystal were 

approximately the same as those for the HUMCO, except the count time was significantly longer. 

The HUMCO II became operational in 1958. The HUMCO II was housed in a count room (SB-16) 

made of seven inches of pre-World War II steel. The resolution was improved, but it remained a 

screening counter. As both of the early in vivo monitoring systems (HUMCO I and II) were used as 

screening counters, NIOSH has not identified that quantitative data are available. 

In 1970, an in vivo counter capable of measuring four separate regions of the body began operation 

(Vasilik, 1983). Twin Phoswich (CsI and NaI) detectors were placed over the lungs. The two layers 

of the detector were capable of simultaneously, yet separately, monitoring chest burdens for 10- to 

250-keV photons (NaI), for plutonium and uranium isotopes and Am-241, and 200- to 2,000-keV 

photons (CsI) for a qualitative assessment of a variety of fission and activation nuclides. A planar 

Hyper Pure Germanium (HPGe) detector monitored the region between 10 and 250 keV with 

excellent energy resolution and could be positioned over the liver or thyroid, as needed. Finally, an 

HPGe (formerly a GeLi) detector was positioned under the prone subject. This detector was primarily 

for whole-body assessment. This system could both identify radionuclides and quantify the burdens. 

All individuals who received lung counts were monitored for Pu-239 and Am-241. In recent years, 

routine U-235 and Th-234 (as U-238) were added to the routine in vivo analysis library. 

In August 1959, the Health Physics group acquired a probe to be used to monitor wounds 

contaminated with plutonium. This probe was capable of detecting soft plutonium X-rays. Wound 

counting was used primarily as a tool for surgeons to locate plutonium in the wound, not as results 

used to calculate internal dose. 

Tables 6-4, 6-5, and 6-6 summarize LANL in vivo data available to NIOSH. The listed radionuclides 

represent the gamma spectroscopy photopeak identification system capability. Blank entries indicate 

that the corresponding radionuclide was not positively identified. 

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Table 6-4: LANL Chest Monitoring Data 

Year Am- 241 As- 72 C-11 N-13 Cd- 109 Cm- 244 Co- 57 Co- 60 Cs- 137 Eu- 152 Hg- 197 Hg- 203 Pb- 212 Pu- 238 Pu- 239 Sc- 46 Ta- 179 

1969 41 4 45 

1970 351 12 358 1971 187 2 80 177 1972 384 60 359 1973 461 14 416 1974 481 2 477 1975 834 2 2 820 

Notes: Data values = Number of analytical results available, radionuclides with no results indicate there were no records with positive results. Som

Table 6-5: LANL Other In Vivo Monitoring Data 

Year 

Back Hand Hand 

Wound 

Liver Skull Thy

Pu-238 Am-241 Co-60 Pu-239 Am-241 Am-241 Am-241 I-125 

1969 1970 1971 1972 1973 2 1974 1975 

Notes:

Data values = Number of analytical results available, radionuclides with no results indicate there were no records with posit

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Table 6-6: LANL Whole Body Monitoring Data 

Year As- 72 Be-7 Bi- 214 Br- 76 Br- 77 C11 N13 Cd- 109 Ce- 141 Cf- 249 Co- 56 Co- 57 Co- 58 Co- 60 Cr- 51 Cs- 134 Cs- 137 Cu- 64 Cu- 67 Eu- 152 

1963 1964 1965 1966 1967 1968 1969 1 1 1970 2 

2 

16 16 16 

1971 3 3 3 1972 1 

1 

7 6 6 

1973 47 55 47 1974 1 

1 

8 8 8 

1975 2 

2 

13 13 13 

LANL Whole Body Monitoring Data (cont.) 

Year Hg- 203 MAP FP Mn -54 Na- 22 Na- 24 Nd- 147 Os- 185 

P32 Ra- 226 Rb- 83 Rb- 84 Sb- 124 Sc- 46 Se- 75 Sm- 145 Ta- 179 Tl- 201 Tl- 202 

1963 14 1964 1965 1966 1967 1968 1969 1970 2 

2 

4 

10 

1971 1 1972 2 1 

1 

4 2 

1973 1974 1 1 1975 1 2 4 

Notes:

Data values = Number of analytical results available; MAP = Mixed Activation Products; FP = Fission Products, radionuclides with no resuwith positive results. Additional data are available post-1975. 

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6.2 LANL External Monitoring Data 

The following information provides a general summary of the LANL external monitoring program, as 

well as the types, quantity, and quality of the data that can be used for external dose reconstruction. 

Details regarding the various analyses used, the associated MDAs, the calibration procedures 

employed, and missed doses are available in the LANL Occupational External Dose TBD (ORAUTTKBS-0010-6). 

Records of individual radiation doses determined from personnel dosimeters worn by the worker and 

co-workers are available for LANL operations beginning in 1943. Doses from these dosimeters were 

recorded at the time of measurement and routinely reviewed by operations and radiation safety staff 

for compliance with radiation control limits. The NIOSH External Dose Reconstruction 

Implementation Guidelines (OCAS-IG-002) have identified these data as the highest-quality records 

for retrospective dose assessments. 

Radiation dosimetry practices were initially based on experience gained during several decades of 

radium and X-ray medical diagnostic and therapeutic applications. These methods were generally 

well advanced by 1940 when the Manhattan Engineer District (MED) program was organized to 

develop nuclear weapons. The primary challenges encountered by MED (and later, the Atomic 

Energy Commission) in attempting to accurately measure worker dose from external radiation arose 

from operations with: 

•	 comparatively large quantities of high-level radioactivity. 

•	 mixed radiation fields involving beta, photon (gamma and X-ray), and neutron radiation with low, 

intermediate, and high energies. 

•	 neutron radiation. 

Historically, LANL had an extensive radiation safety monitoring program using portable radiation 

instruments, contamination surveys, zone controls, and personnel dosimeters for measuring exposure 

in the workplace (Littlejohn, 1960; LASL PEBs: 1959, -69, -77a, 77b, -79, -80; LANL PEBs: 1986, ­

89, -96, 2001, -03). This program was conducted directly by, or under the guidance of, a speciallytrained group of radiation monitors or radiation protection technologists. Results from the dosimeters 

were used to evaluate and record doses from external radiation exposure to workers throughout the 

history of LANL operations. Dosimeters that have been used fall into the following categories: 

•	 Personnel whole-body (WB) beta/photon dosimeters 

•	 Pocket ionization chamber (PIC) dosimeters 

•	 Personnel extremity dosimeters 

•	 Personnel whole-body neutron dosimeters 

Shortly after operations began in 1943, some workers were monitored with PICs alone. LANL 

dosimeter designs differed somewhat from the early to mid-1940s designs at the MED Metallurgical 

and Clinton laboratories, but capabilities to measure doses were similar. By 1945, film badges were 

used by a number of LANL groups, and in 1949 a new badge was introduced to support evaluation of 

beta exposures. Beta/gamma film badge designs changed several times through the 1950s, 1960s, and 

1970s, as filters of various types were used to address the energy dependence of film response. 

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LANL officially switched to the use of thermoluminescent dosimeters (TLDs) in 1980, after the 

timeframe of the class currently under evaluation. Neutron dosimetry was implemented prior to 1949 

for selected workers, beginning with the use of PICs that incorporated Bakelite chambers and graphite 

coatings. In 1949, nuclear track plates were first used; in 1951, badges incorporated Nuclear Track 

Type A (NTA) emulsion film. 

Dosimeters were exchanged on routine schedules. In the earliest operations, daily measurements with 

PICs were performed. When film badges came into use in 1943, daily PIC measurements continued, 

but film measurements provided a check of the daily measurements and formed a permanent record of 

worker exposures. Film packets were exchanged and processed monthly for most workers, but were 

exchanged more frequently (as often as daily) for certain operations with high exposure potential. 

Beta/gamma dosimeters were exchanged at 1- or 2-week intervals, with 2-week intervals 

predominating (LASL PEB, 1959). Nuclear track plates (NTPs) were exchanged at 4-week intervals. 

Table 6-7 summarizes the LANL dosimetry exchange frequencies during the evaluated time period. 

Table 6-7: Summary of Typical Exchange Frequencies for LANL Dosimeters 

Dosimeter type Date range Exchange frequency 

PICs Prior to 1945 Daily 

Film Badges 1943 – 1979 Monthly for some, biweekly for some, up to daily for some operations 

NTPs 1949 – approx. 1951 4-week interval 

NTA Film 1951 – 1995 4-week interval 

Table 6-8 presents a listing of reported numbers of workers monitored by LANL from 1944 through 

1975 (LANL, 2004). 

Table 6-8: Annual LANL External Radiation Doses, 1944–1975 

Year Number of workers monitored 

1944 9 

1945 812 

1946 508 

1947 1,237 

1948 2,080 

1949 3,177 

1950 3,895 

1951 4,257 

1952 2,366 

1953 1,878 

1954 2,068 

1955 1,984 

1956 2,287 

1957 2,539 

1958 3,032 

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Table 6-8: Annual LANL External Radiation Doses, 1944–1975 

Year Number of workers monitored 

1959 2,930 

1960 3,622 

1961 3,973 

1962 4,119 

1963 4,176 

1964 4,103 

1965 4,222 

1966 4,446 

1967 4,072 

1968 3,861 

1969 3,980 

1970 4,031 

1971 3,775 

1972 3,877 

1973 3,866 

1974 4,337 

1975 4,716 

Details regarding the various analyses used and the associated MDLs are presented in the Technical 

Basis Document for LANL Occupational External Dose (ORAUT-TKBS-0010-6). 

6.3 LANL Air Sampling Data 

Prior to 1971, air monitoring data for most TAs were not available, or if available, do not provide a 

complete record. Estimates of occupational intakes provided in the LANL Internal TBD rely on 

emissions data provided by LANL. These data indicated several years prior to 1971 in which 

potentially significant releases (and thus intakes) might have occurred. In particular, early plutonium 

releases at TA-1 are high in relation to other years, and there are two years of very high Th-232 

releases (i.e., TA-15 in 1967-68). These apparently-high releases, surrounded by years of either zero 

releases or missing emissions information, suggest that more investigation is needed regarding the 

accuracy of the reported releases and the completeness of the emissions data before pre-1971 intakes 

can be adequately addressed. Therefore, estimated worker intakes in the TBD are restricted to 

post-1970 years. Efforts are currently in progress to develop pre-1971 intakes for a future revision of 

the TBD. Recently, approximately 4,000 documents were obtained from LANL, including monthly 

effluent stack release summaries and raw count room log book data. Reviews of these documents 

identified stack and room monitoring data from the 1940s through the 1970s. The majority of the 

results were limited to TA-3, although some results were provided for TA-1, -21, and -35. In some 

instances, the data provided the type of radionuclide or gross activity analysis performed; however, 

many of the data sheets provided no information on the type of testing. Summary Radioactive 

Effluent Release Reports provided total activity released as a roster of relevant radionuclides from a 

given stack. A typical example roster make-up was: 1967, TA-3-29-CMR Bldg., (stack) 5 FLMX-1: 

Pu-239, U-235, U-238, Np-237, Th (natural), Am-241, tritium. (Chelius, 1970). 

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7.0 Feasibility of Dose Reconstruction for the Proposed Class 

The feasibility determination for the proposed class of employees covered by this evaluation report is 

governed by both EEOICPA and 42 C.F.R. § 83.13(c)(1). Under that Act and rule, NIOSH must 

establish whether or not it has access to sufficient information either to estimate the maximum 

radiation dose for every type of cancer for which radiation doses are reconstructed that could have 

been incurred under plausible circumstances by any member of the class, or to estimate the radiation 

doses to members of the class more precisely than a maximum dose estimate. If NIOSH has access to 

sufficient information for either case, NIOSH would then determine that it was feasible to conduct 

dose reconstructions. 

In determining feasibility, NIOSH begins by evaluating whether current or completed NIOSH dose 

reconstructions demonstrate the feasibility of estimating with sufficient accuracy the potential 

radiation exposures of the class (discussed in Section 9.0 of this report). If the conclusion is one of 

infeasibility, NIOSH systematically evaluates the sufficiency of different types of monitoring data, 

process and source or source term data, which together or individually might assure that NIOSH can 

estimate either the maximum doses that members of the class might have incurred, or more precise 

quantities that reflect the variability of exposures experienced by groups or individual members of the 

class as summarized in Section 7.6. This approach is discussed in OCAS’s SEC Petition Evaluation 

Internal Procedures which are available at http://www.cdc.gov/niosh/ocas. The next four major 

subsections of this Evaluation Report examine: 

• the sufficiency and reliability of the available data. (Section 7.1) 

• the feasibility of reconstructing internal radiation doses. (Section 7.2) 

• the feasibility of reconstructing external radiation doses. (Section 7.3) 

• the bases for petition SEC-00051 as submitted by the petitioner. (Section 7.4) 

7.1 Pedigree of LANL Data 

This subsection answers questions that need to be asked before performing a feasibility evaluation. 

Data Pedigree addresses the background, history, and origin of the data. It requires looking at site 

methodologies that may have changed over time; primary versus secondary data sources and whether 

they match; and whether data are internally consistent. All these issues form the bedrock of the 

researcher’s confidence and later conclusions about the data’s quality, credibility, reliability, 

representativeness, and sufficiency for determining the feasibility of dose reconstruction. The 

feasibility evaluation presupposes that data pedigree issues have been settled. 

Extensive work to determine the pedigree of 1943-1970 LANL monitoring data has not been 

performed because those years are being recommended for SEC inclusion. This recommendation is 

based on an identified lack of monitoring data necessary to perform dose reconstructions for the 

proposed class for that time period. Data retrieval efforts have been made over the past several years 

to identify sufficient worker, area, and environmental monitoring records for many of the lesser 

radionuclide source terms. These efforts have identified the availability of some air sampling results 

for specific rooms or buildings. However, in many cases the results are reported as gross activity, or 

the analysis type is not specified. Even when radionuclide-specific, the data are too limited in scope 

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for adequate modeling of all the potential exposure scenarios that would have to be taken into account 

in order to address the data gaps in bioassay monitoring. 

Summaries of currently-identified internal and external data pedigree information are presented in the 

following subsections. 

7.1.1 Internal Data Review 

Initial acquisition and use of pre-1990 LANL internal monitoring data for EEOICPA claimant dose 

reconstructions was problematic. Most of the original LANL bioassay data were archived from 

legacy computer systems and was recorded in a variety of formats that made it very difficult to use, 

particularly by non-LANL personnel. Data retrieval proved to be a daunting task for LANL staff as 

they attempted to provide timely, complete, and accurate claimant data sets to NIOSH dose 

reconstructors. In addition, older bioassay data had not been validated when it was converted into 

electronic data after the original dose calculations were completed. In vivo data did not have assigned 

MDAs and only records with positive results were retained. Older in vivo data were stored in a 

different location from the newer data. 

As a result, in the summer of 2004, LANL and NIOSH representatives agreed to undertake a joint 

effort to collect, validate, verify, and upload LANL internal monitoring data into a central repository 

suitable for efficient retrieval during the NIOSH dose reconstruction process. Results of this effort 

have been documented in Los Alamos National Laboratory (LANL) Bioassay Data Project Final 

Report (ORAUT-OTIB-0063, draft). This report has served as the source for the summary LANL 

internal data review information presented below. Because of the nature of the effort, not all results 

summaries are limited to the 1943-1975 class timeframe. 

7.1.1.1 In Vitro Monitoring Data 

Original urine assay results for tritium, uranium, and polonium (TUPo) were recorded in bound Los 

Alamos Notebooks (LANBs). The notebooks were not dedicated to a specific process or procedure, 

but rather were issued to individuals. Consequently, urine assay results prior to 1990 are distributed 

among 120 LANBs. A specific notebook may contain several thousand records, or only a few, 

depending on the use of the notebook by the assigned individual. During early LANL operations 

(pre-1970), it was not uncommon for the lab to record only positive bioassay results and to not report 

MDA values. In addition, record-keeping standards have changed significantly through the years, 

creating data retrieval challenges. 

Around 1955-1956, LANL began the process of recording dosimetry records on IBM punch cards. 

Since that time, the data have existed in electronic format on several different systems. The data were 

first on Control Data Corporation (CDC) computers using the Network Operating System (NOS); then 

the CDC system was replaced by Digital Equipment Corporation (DEC) VAX. 

Documentation of the VAX file data fields was not found. Delineation and definition of data fields 

was determined through personnel interviews and examination of lab notebooks. The data fields of 

the VAX files varied from nuclide to nuclide, and from file to file for a specific nuclide. It was 

necessary to work with each file individually to determine what data were provided and in what 

format. 

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The VAX ASCII data files were written to a compact disc (CD) and then individually imported to 

Microsoft Excel spreadsheets in order to determine and define the record fields. The spreadsheets 

were in turn exported to a Microsoft Access Database and merged into a single flat table. Finally, the 

table data were imported into an Oracle Database for incorporation into the LANL Bioassay 

Enrollment, Scheduling and Tracking (BEST) system. The total number of records for the TUPo data 

is in excess of 147,000. 

From the VAX data files, 120 LANBs were identified as containing TUPo data through 1990. A 

request for access to the physical notebooks was made and, to date, 90 notebooks have been provided. 

Of the 90 notebooks, it is evident that references to 12 of these notebooks are incorrect, as they 

contain no TUPo data. However, the notebooks that have been provided represent nearly 90% of the 

TUPo records through 1990. Thirty physical LANBs remain to be reviewed. It is possible that some 

LANB references in the VAX files are incorrect or are typos. If so, the remaining referenced 

notebooks may be at LANL archives, may not actually exist or, if they do, may not contain TUPo 

information. 

Just over 11 percent (16,692 out of 147,690) of the TUPo records were validated. Data comments 

were inserted on 4882 records and approximately 1300 records were in some way corrected. Errors 

were found in the reporting of sample results, sample date, and notebook and page references. One 

hundred thirty-four records that had been omitted from the VAX files were added to the database. A 

significant number of the data comments do not reflect actual corrections or data changes. These 

comments may indicate that the data reviewer had unresolved questions about the record or may 

indicate errors that were apparent but could not be corrected (e.g., an obviously-incorrect notebook 

reference – but the actual notebook could not be determined). Data validation results for TUPo 

analyses are summarized below followed by a short description of “Other Radionuclide Data.” 

Tritium Data 

Approximately 10% (5,170 out of 50,141) of the tritium records were validated. Thirty-four records 

that were present in the LANBs but not in the VAX files were added to the database. Data comments 

were inserted on 3,563 records and corrections were made to about 138. The tritium data for the 

period 6/23/50 through 12/31/90 were extracted from the six VAX data files listed in Table 7-1. 

Table 7-1: Tritium VAX Data Files 

File Name No. of Records Comments 

seza5063 17,737 Tritium records from 6/23/50 through 12/31/63 

seza6475 9,932 Tritium records from 1/2/66 through 12/31/74 

seza7683 9,961 Tritium records from 1/3/75 through 12/30/83 

seza8488 8,099 Tritium records from 1/3/84 through 12/30/88 

st389 1,989 Tritium records from 1/3/89 through 12/28/89 

st390 2,389 Tritium records from 1/2/90 through 12/31/90 

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In comparing the LANB data with the VAX files, it was evident that the bioassay results had been 

adjusted in some manner yet to be determined. In general, the VAX file results values were 1-10% 

higher than those documented in the LANBs; approximately 3,460 records were affected. NIOSH 

assumes that some global correction was made to the data upon entry into the VAX files, but currently 

this difference remains unresolved. Results of the tritium data validation are summarized in Table 

7-2. 

Table 7-2: Tritium Data Validation Summary 

Total No. 

of Records 

No. of 

Validated 

Records 

Records 

Added 

Corrected Fields No. of Data 

Comments Sample 

Results 

Sample 

Date 

Notebook 

Reference 

Page 

Reference 

50,141 5150 34 45 2 12 51 3564 

Uranium Data 

The TUPo database contains 43,668 results for U-235, and 48,169 results for U-238, for a total of 

91,837 records. For U-235, the bioassay data covered the period from 4/6/55 through 12/31/1990. 

The U-238 data covered a period from 11/18/49 through 12/31/1990. Uranium data were extracted 

from the 15 VAX files listed in Tables 7-3 and 7-4. 

Table 7-3: VAX Data Files Containing Uranium-235 Data 

File Name No. of 

Records Comments 

sag5574 8,953 U-235 records for last names “A” to “G” from 4/08/55 through 12/20/74 

shn5574 7,352 U-235 records for last names “H” to “N” from 4/11/55 through 12/20/74 

soz5574 10,151 U-235 records for last names “O” to “Z” from 4/06/55 through 12/20/74 

su57581 11,594 U-235 records from 1/03/75 through 12/25/81 

su235az.1982-88 4,929 U-235 records from 12/25/81 through 12/19/88. (Also includes two data records dated 

7/09/62 that are of questionable value based on examination of LANB data.) 

su5o89 272 U-235 records from 1/03/89 through 12/18/89 

su5o90 400 U-235 records from 1/02/90 through 12/31/90 

Table 7-4: VAX Data Files Containing Uranium-238 Data 

File Name No. of 

Records Comments 

su238a 9,889 U-238 records for last names “A” to “G” from 11/18/49 through 12/13/74 

su238b 9,699 U-238 records for last names “H” to “N” from 11/18/49 through 12/13/74 

su238c 10,014 U-238 records for last names “O” to “Z” from 11/18/49 through 12/13/74 

su87581 11,830 U-238 records from 1/03/75 through 12/25/81 

su238az.1982-88 5,159 U-238 records from 2/19/81 through 12/21/88 

su8o89 604 U-238 records from 1/03/89 through 12/19/89 

su8o90 959 U-238 records from 1/02/90 through 12/31/90 

sPOL4765. 

dat 6 These records were found in the polonium VAX data, but LANL information indicated these 

were U-238 results dated 2/17/56. 

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In addition to the VAX data files identified as containing uranium bioassay data, six U-238 records 

were found in the file “sPOL4765.dat” that should have contained only polonium data. The fact that 

these records were uranium assay results, and not polonium, was verified through examination of the 

laboratory notebooks. 

Seventeen U-235 and fifteen U-238 records that were present in the LANBs but not in the VAX files 

were added to the database (this included the six U-238 records found in file “sPOL4765.dat”). 

Corrections and comments were made on 76 U-235 records and 803 U-238 records. Results of the 

uranium data validation are summarized in Table 7-5. 

Table 7-5: Uranium Data Validation Summary 

Nuclide 

Total No. 

of 

Records 

No. of 

Validate 

Records 

Records 

Added 

Corrected Fields No. of Data 

Comments Sample 

Results 

Sample 

Date 

Notebook 

Reference 

Page 

Reference 

U-235 43,668 4436 17 32 0 1 79 76 

U-238 48,169 4841 15 60 10 2 6 803 

Total 91,837 9,277 32 92 10 3 85 879 

Polonium Data 

Polonium data available for the period 3/11/47 through 3/24/65 were extracted from a single VAX 

data file. Comparing to retrieved notebook values, nearly 40% (2,245 of 5,712) were validated. 

Thirty-six records that were present in the LANBs but not in the VAX files were added to the 

database. Corrections and comments were made on 439 records. Results of the polonium data 

validation are summarized in Table 7-6. 

Table 7-6: Summary of Errors in Validated Polonium Data 

Total No. 

of Records 

No. of 

Validated 

Records 

Records 

Added 

Corrected Fields No. of Data 

Comments Sample 

Results 

Sample 

Date 

Notebook 

Reference 

Page 

Reference 

5,712 2,245 36 72 0 553 395 439 

Other Radionuclide Data 

Bioassay data were not found for LANL workers who worked with radioactive lanthanum (RaLa). 

Similarly, other less-common radionuclides like strontium-90 (a RaLa contaminant), Th-232, Ac-227, 

and Cm-244 were not part of the routine bioassay program. However, LANL did record a very 

limited number of Sr-90 results using gross beta analyses. 

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In vitro data for mixed fission products (MFP) are in the same category as the RaLa data – in general, 

they do not exist. While isolated results may exist in the laboratory notebooks, no regular 

programmatic sampling data exist. Limited in vivo counting was accomplished for MFP; however, 

the number of results are insufficient to provide a co-worker data set. 

7.1.1.2 In Vivo Monitoring Data 

Prior to the recent consolidation efforts by LANL and NIOSH (see Section 7.1.1 and ORAUT-OTIB0063, draft), in vivo counting data from 1960-2003 were maintained in a legacy system called 

“OMNIS7”. This older database does not provide MDA values and only contains count data for 

positive results. Some in vivo measurements are available for the pre-1960 period; however, these 

measurements were not considered routine, and therefore are not described as a regular part of the 

LANL in vivo bioassay program. The in vivo program expanded in 1970, and began using more 

sensitive instrumentation (see Section 6.1.3). Some paper records do exist, such as “beige” and 

“white” cards that contain analyst comments regarding how the radionuclide activities were calculated 

for individuals as well as important physiological information (e.g., chest wall thickness). 

As a result of LANL and NIOSH consolidation efforts, the 1960-2003 in vivo data have been 

combined with post-2003 data into one Oracle database. Resource constraints prevented importing 

and scanning the historical “beige” and “white” cards; however, the database is configured so that 

after these cards are scanned, the values can be entered later. Tables containing typical MDA values 

for older in vivo counting systems were also added to the Oracle database so that MDAs could be 

assigned to all counts performed based on time period. At this point, it appears that not much can be 

done to recreate the actual MDA values for older measurements. 

7.1.2 External Data Review 

LANL dosimetry capabilities during the early years were in line with the prevailing stage of 

technological development. Over time, LANL’s radiation dosimetry technology developed 

considerably, keeping up with technological developments as they became accepted. Administrative 

practices are described in the Photodosimetry Evaluation Book (Littlejohn, 1960; LASL PEBs: 1959, ­

69, -77a, 77b, -79, -80; LANL PEBs: 1986, -89, -96, 2001, -03). and LANL technical reports. 

Detailed information for each worker is in the NIOSH claim documentation. Based on the claim 

documentation, there do not appear to have been significant administrative practices jeopardizing the 

integrity of the recorded dose of record. 

From 1943 through 1952, external radiation evaluation results were recorded in standard “LA 

notebooks” that eventually found their way to the document room for permanent storage (LASL PEB, 

1959). In August 1950, H Division started supplying PICs and film badges for use by the “GMX-1” 

(the early Radiography Group) during “extraordinary work” (LASL PEB, 1959). Prior to that time, 

dosimetry for the GMX-1 group was reportedly handled by GMX-1 personnel at GT Site; apparently, 

no long-term records of these early measurements were retained. 

According to a February 16, 1956 memorandum, in January 1953 a “Cardex” system for filing 

exposure data on paper cards was put into use (LASL PEB, 1959). In January 1956, LANL started 

noting all nuclear track plates (NTPs) issued on Personnel Exposure Cardex records. Prior to this 

time, only plates that were "read" were recorded (LASL PEB, 1959). 

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According to an April 3, 1957 memorandum, in 1957 a computerized “IBM” system was first 

employed at LANL to record personnel exposures to radiation (LASL PEB, 1959). Also in 1959, 

IBM equipment was first used to evaluate film exposures (Littlejohn, 1960). This record-keeping has 

been computerized since that time. 

In September 1978, it was reported that, for the previous 10 years, no entry was made in the 

computerized records system for any visitor’s film badge exposure reading less than 0.04 rem (LASL 

PEB, 1980). For purposes of reporting to the visitor’s primary employer, a non-zero exposure 

recorded by the LANL Cycolac film badge was defined as a total-rem exposure of 0.04 rem or more. 

(For regularly-issued film badges, all measured values from 0.00 rem upward were recorded and 

attributed to the worker in the H-1 dosimetry records system.) This visitor film badge policy was in 

place to preclude dose reporting of <0.04 rem (which would have required tracking down each visitor 

to obtain employer name and address). An October 30, 1979 memorandum indicated that on January 

1, 1976, LANL had to start reporting zero exposures for all Energy Research and Development 

Administration (ERDA) visitors, because ERDA had just established a radiation exposure record 

system for all its employees (LASL, 1980). 

As mentioned earlier, the scope of data pedigree investigations has been limited due to 

recommendation of the 1943-1975 timeframe for SEC status. Consistency checks between older 

external monitoring data repositories and reports are, therefore, not necessary for this timeframe. 

7.2 Internal Radiation Doses at LANL 

The principal sources of internal radiation doses for members of the proposed class were inhalation, 

ingestion, or absorption of plutonium isotopes, Am-241 (as pure Am-241, separate from the typical 

association with plutonium), uranium isotopes, Po-210, Ac-227, Th-232, H-3, mixed fission and 

activation products (primarily Cs-137 and Sr-90), and radium. The isotopic composition of the 

plutonium was consistent with weapons-grade material. The chemical forms for plutonium that could 

potentially be encountered included metal, nitrate, and fluoride. Depleted uranium (DU) metal and 

uranium oxide were most commonly encountered, but natural and enriched uranium were used as 

well, as was U-233. Po-210 and Ac-227 were used to construct nuclear weapon initiators. Oxide and 

metallurgical activities involving Th-232 were noted. Tritium was involved in various aspects of 

weapons research and was a by-product of accelerator operation. There were several research 

reactors operational over the life of the site that resulted in mixed fission product contamination that 

could have resulted in personnel exposure during operation, maintenance, and demolition of the 

facilities, and during investigations of spent fuels (ORAU-TKBS-0010-2). 

Intake of these radionuclides could have resulted from either routine or off-normal events. Processes 

involving these materials included machining, casting, grinding, blending, chemical reactions, testing 

(including explosive testing), or other operations that could directly cause airborne radioactivity or 

release contamination to work surfaces where it could be re-suspended. 

When LASL operations began in 1943, the only method of monitoring intake was through loose 

contamination swipes. Lightly-oiled filter papers were swiped across surface areas likely to be 

contaminated. Any swiped area with an activity of more than 500 cpm (1,000 dpm) alpha required 

decontamination. The efficiency of the stationary counters used to count the swipes approached 50%. 

In addition, nasal swipes (also called “nose counts”) were used to indicate potential intakes. Nasal 

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swipes with alpha activity more than 50 cpm indicated the need for follow-up urinalysis. The first air 

samplers became available in fall 1944. However, the swipe technique continued as the primary 

method of detection in many areas until the early 1950s. Respiratory protection equipment (e.g., 

assault gas masks or respirators) was used as early as 1944. 

In 1943, project hazards were limited to external radiation from the cyclotron, the Van de Graaff 

accelerator, radium sources, and a few micrograms of plutonium that arrived that summer. In 

addition, there were some internal and external radiation hazards from uranium. 

In 1944, the radiological hazards of plutonium had been recognized, but it was not yet realized that 

plutonium was more hazardous than radium. Safety regulations were established based on experience 

with radium dial paint plants. Measures to control personnel exposures included multiple changes of 

clothing, showering before leaving the building, use of surgical gloves and respirators, and use of 

closed systems whenever possible. These measures were primitive by current standards. Most 

workers cooperated with safety rules to the best of their ability, but the potential for contamination 

and intakes was present. During the tension and feverish activity of developing the first atomic bomb, 

it was difficult to avoid some shortcuts in the observation and enforcement of safety rules. In 

addition, the first experimental reactors went on line in TA-2 in 1944. 

The Laboratory went from handling a few micrograms of plutonium in 1943 to kilogram quantities in 

1945. This provided little time for the usual development of safe methods of handling and safety 

equipment design. As research determined that plutonium was more hazardous than radium, tolerance 

levels and maximum permissible burdens were reduced significantly. 

Early safety efforts were based on working in safe contamination levels. In 1954, contamination-level 

measurements were based on contact with a shield open Geiger-Mueller (GM) tube for beta/gamma 

and a Pee Wee probe of 55 cm2

 area for alpha. The efficiency of these portable probes is 

approximately 10% to 15%. Swipes counted on a fixed proportional counter had an efficiency of 

approximately 40% to 50%, although the oil used on the swipes (to increase collection efficiency) 

might have decreased the counting efficiency slightly. A total alpha count rate of 500 cpm on a swipe 

corresponded to 0.007 μg or 0.0004 μCi of the plutonium isotopic mixture of the times. 

The tolerance for wounds was 10 cpm for alpha and 0.15 mrep/hr beta/gamma, except for wounds 

contaminated with Sr-90 for which the tolerance was 0.05 mrep/hr. The skin contamination tolerance 

was 1 mrep/hr beta/gamma, except for Sr-90, which was 0.05 mrep/hr. The skin contamination 

tolerance for alpha emitters was 1,000 cpm for polonium, 500 cpm for Tuballoy (natural uranium) or 

Oralloy, and 250 cpm for plutonium. The tolerance for floor counts was 100 cpm/swipe alpha but 

definitely less than 500 cpm/swipe alpha, and bench tops were usually 50 cpm/swipe alpha or less. 

Floors in laboratories were mopped once or twice a day to maintain safe contamination levels. Early 

Health Group reports indicate contamination present inside many of the respirators signifying 

improper storage, handling and/or poor fit during use. 

Kilogram quantities of plutonium began to arrive at LASL in April 1945. At that time, portable alpha 

counters, continuously-operating air samplers, supplied air lines, and specially-made positive pressure 

masks were available. Procedures were performed in open hoods and wooden dry boxes, which were 

the precursor to the modern glovebox. Research indicated that there was a potential for work-related 

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and casual encounters with plutonium and other radionuclides at various air concentrations and/or 

surface contamination levels, including levels that exceeded radiation exposure or control limits. 

Given that these operations were, in many cases, the first of their kind and that health physics 

practices were being developed and implemented at the same time plutonium processes were being 

brought online, some level of chronic or episodic intake during this period would be a reasonable 

assumption. From 1943, the Health Group was responsible for establishing health standards, 

specifically for safe levels of exposure to radiation and to radioactive and chemical materials. The 

Health Group’s primary concern was to protect the health of laboratory employees. Until mid-1951, 

for want of adequate staff, the Group accepted help in monitoring radiation-related activities from the 

Chemistry and Metallurgy Research (CMR) organization staff. Over the years, the Health Group 

evolved into the Health Division [and its successors, Environmental, Safety, and Health (ESH) and 

Health, Safety, and Environment (HSE) Divisions], with multiple groups therein to address health 

physics, medical, (industrial) safety, biomedical research, industrial hygiene, industrial waste 

treatment, and environmental studies. While several division and group name changes have occurred 

since 1943, the generic Health Physics Group has existed since 1951. Throughout this period, that 

group has had the responsibility for assigning and scheduling bioassay analyses for intakes of all 

radioactive materials. Until the late 1990s, the Industrial Hygiene Group performed all bioassay 

analyses. Since the late 1990s, bioassays have been performed by one of the chemistry groups. The 

Medical group has treated individuals accidentally exposed to radiation and radioactive materials, 

performed physical examinations, and treated industrial accidents. 

Over the years, many improvements have been made in monitoring, bioassay techniques, safety 

equipment, and safety procedures. Nevertheless, the potential for monitored and unmonitored intakes 

has existed throughout the history of the site. 

Excreta bioassay methods for determining internal exposures were developed in late 1944 for 

plutonium (fully implemented in April 1945) and polonium; for uranium in 1949; and for tritium in 

1950. Although the number of monitored individuals increased over the years, not all individuals 

working at LANL were monitored. Emphasis was placed on monitoring workers with the highest 

exposure potential or who had incurred a suspected intake. A survey taken in 1986 estimated that 

approximately 350 persons had known burdens of plutonium. 

Starting in 1944, blood tests were performed following potential exposures. However, these blood 

tests were performed for blood count levels related to external radiation exposure rather than the 

radioactive content of the blood. Therefore, any records of blood counts performed on an individual 

or mentioned in the claimant interviews will not be directly applicable to internal dose calculations. 

Air samples, identifiable with an individual’s record, were performed beginning in 1944. However, 

since these samples were used to indicate potential elevated airborne conditions, and thus to select 

personnel for bioassay, there is no clear-cut method to derive a dose estimate for individuals unless a 

bioassay was performed. Records of chelation therapy for plutonium and americium are noted in the 

bioassay record. 

As state-of-the-art of radiation detection progressed, whole-body counting for fission products began 

in 1955, wound counting began before 1967, and chest counting began in 1970. However, as noted 

previously, NIOSH has been unable to locate these early whole-body counting results 

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7.2.1 Process-Related Internal Doses at LANL 

The following subsections summarize the extent and limitations of information available for 

reconstructing the process-related internal doses of members of the proposed class. 

7.2.1.1 Urinalysis Information and Available Data 

Two sources of urinalysis data are available, although they undoubtedly arose from the same database: 

1. The Microsoft Access database, “LANL Co-Worker Data-Rev 1”, contains urinalysis results for 

Pu-238, Pu-239, and Po-210 from 1945 through 1988. Data for these three radionuclides were 

used to develop the draft technical information bulletin ORAUT-OTIB-0062 (draft). Tritium 

urinalysis results for 1950 through 1988 can be found in “LANL CO-Worker Complete”. As 

noted previously, Am-241 urinalysis data have recently been identified but are not contained 

within this database. 

2. The “LAMULW02 Working Data” file set was prepared by LANL for epidemiological studies for 

workers from 1944-1978. This database was queried by the NIOSH Task 5 Co-worker Team to 

provide specific information contained in the following files (http://cedr.lbl.gov/cgibin/spiface/find/cedrdfs/def?DATASET=lamulw02): 

•	 Labfile1, Labfile2, Labfile3, and Labfile4: Contain plutonium bioassay data from 1944 

through October 1985. There are 43,693 records in each file. All urine bioassays before 1968 

were for Pu-239. Thereafter, results are labeled Pu-238, Pu-239, or (a small number) Pu-242. 

•	 LATFILE: Contains 6,662 revised annual tritium readings from 1950 to 1988. 

Prior to the 1970s, individuals were assigned to a bioassay program as determined by the area Health 

Physics monitors. LANL deemed this program sufficient to ensure that all workers who might require 

monitoring were monitored. However, instances might have occurred (especially in the early years) in 

which a person not normally assigned to radiation work was asked to participate as a substitute in a 

task involving radiation or radioactive materials. These persons were not likely to have regularly, or 

possibly ever, participated in the bioassay program. It is possible that their participation in these tasks 

was never recorded. Dose reconstructors may learn information about this type of exposure from their 

review of the claimant interviews (CATIs). 

The Zia Company was the service workers’ contractor. Zia employees participated in a separate 

monitoring program from that used for laboratory employees. It appears that sometime in 1976, Zia 

employees had a special computer program that locked out access to plutonium areas if participation 

in a plutonium bioassay program was not recorded within 425 days. 

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In the 1970s, LANL initiated an Employee Health Physics Checklist. This checklist allowed the 

evaluation of each individual for potential internal and external exposure. Individuals were placed on 

a monitoring schedule based on this checklist. The checklist is still used and was computerized in 

1998 as the Dosimetry Enrollment System. 

Plutonium 

The most serious intakes at LANL have involved isotopes of plutonium. The first urinalysis 

performed for evidence of plutonium uptake was performed on July 18, 1944 using a chemical 

procedure developed at the University of Chicago Metallurgical Laboratory in June 1944. However, 

Health Group personnel soon discovered that the procedure, using a 50 cm3

 aliquot of a 24-hour urine 

sample, did not have the sensitivity to meet the tolerance level of a 5-μg (0.33-μCi) burden of 

plutonium. The first recorded accident in which a human was subjected to a possible intake of 

plutonium occurred on August 19, 1944. This accident resulted in LASL being authorized to proceed 

with development of a more sensitive procedure. Current and historical bioassay results are stored 

with the plutonium results in the Los Alamos Bioassay Data Repository database. Data are available 

and internal plutonium doses can be reconstructed for the period after 1945. However, the plutonium 

isotopic distribution is not available and early results are reported as plutonium or Pu-239. For dose 

reconstruction, the values should be considered total plutonium alpha counts, which would include 

Pu-239, Pu-240, and Pu-238. Data providing the nominal isotopic distribution for weapons-grade 

plutonium are available in ORAUT- TKBS-0010-5. Missed dose can be estimated using the 

information for this timeframe presented in Table 5-5 of ORAUT-TKBS-0010-5. The optimum 

source of data to estimate doses to unmonitored workers is co-worker data analyzed per ORAUTOTIB-0019. This analysis has been performed and documented in ORAUT-OTIB-0062 (draft). The 

co-worker data were evaluated to model intakes to derive dose estimates for Pu-239 prior to 1945 and 

for Pu-238 prior to 1968. Intakes prior to these timeframes would require extrapolation of the intake 

models. 

Americium 

At LANL, Am-241 is usually encountered as a trace contaminant in plutonium; however, there is 

potential for exposure to pure Am-241. No exposure to pure Am-241 was likely prior to the 

beginning of the americium bioassay program in 1954, although a procedure for determining Am-241 

in urine was in development in 1948. Current and historical bioassay results are stored with the 

plutonium results in the Los Alamos Bioassay Data Repository database. 

There is an indication that workers participated in the americium bioassay program only if there was a 

potential for exposure to pure americium. Therefore, plutonium mixtures cannot be inferred from 

americium bioassay results. Conversely, the dose contribution from Am-241 cannot be excluded 

based on the absence of (Am-241) bioassay data since it is a known component of plutonium 

mixtures. Doses from unmonitored intakes of Am-241 associated with plutonium exposure can be 

inferred from plutonium bioassay results using isotopic ratios typical of weapons-grade plutonium 

found in ORAUT-OTIB-0053 (draft). For the pre-1970 (pre-in vivo) time period, the ability to 

reconstruct Am-241 dose will be extremely limited if plutonium and/or americium data are not 

available (from bioassay, co-worker, source term, or area monitoring data), or until such time that the 

newly-identified data have been validated and made available for use in dose reconstructions. 

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Tritium 

Tritium was encountered in several forms: tritiated water (HTO), tritiated gas (HT), organically-bound 

tritium (OBT), and metal tritide (MT). Each form has unique characteristics. Since 1950, an average 

of around 100 individuals per year has been monitored for tritium intakes at LANL. The form 

generally encountered was HTO. There are no records of tritium monitoring prior to 1950. 

Therefore, the ability to reconstruct tritium contribution to internal dose to workers in applicable TAs 

will be extremely limited, pre-1950, given the lack of a surrogate evaluation model, a developed coworker study, or an established extrapolation methodology. Urinalysis for tritium began on January 1, 

1950; data are available in the Los Alamos Bioassay Data Repository database. The co-worker data 

were sufficient to derive dose estimates for tritium after this date. 

Uranium 

Historically, uranium at LANL was primarily depleted or enriched with a variety of isotopic ratios. 

Depleted is the most common form of uranium encountered at LANL, although natural uranium 

(Tuballoy) was used in conventional weapons testing from 1949 to 1970. 

The most commonly-encountered chemical forms of uranium were oxides and metal. LANL has 

always treated uranium as either solubility class D or W. Urine assay data suggested that “all known 

LANL exposures to uranium were to a relatively soluble form (not Class Y)”. However, the partition 

between Class D and W could not be determined. Historically, Class W was used for reporting results 

(Lawrence, 1992) because it produced larger doses. Monitoring for uranium consisted of routine 

urinalysis starting in 1949 for employees identified as being at risk for exposure (ORAUT-TKBS0010-5, Table 5A-14). Nasal swipes with more than 50 cpm indicated the need for follow-up 

bioassay. Unless a suitable co-worker cohort can be established for uranium workers who may have 

terminated employment prior to the advent of uranium urinalysis, contributions to internal dose from 

uranium intakes by workers in TAs where uranium was handled cannot be reconstructed prior to 1949. 

Another potential alternative is estimating hypothetical intake rates for workers based on either the 

average or maximum enriched uranium air sampling data where available for the early site years. 

Internal monitoring data are available in the Los Alamos Bioassay Data Repository database and 

internal uranium doses can be reconstructed for the period after 1949. However, isotopic results are 

not available from this early program, although isotopic fractions can be inferred using the 

information in Section 5.2.4 of ORAUT-TKBS-0010-5. Other information useful to dose 

reconstruction (i.e., solubility fraction, analytical methods, MDAs, etc.) can be found in ORAUTTKBS-0010-5. The co-worker data were sufficient to derive dose estimates for unmonitored workers 

for uranium after January 1, 1950. 

Fission Products 

The first gross beta urine count was devised in 1947. References to the site’s ability to perform 

urinalysis to monitor for fission product intakes have been seen in various Health Division reports. 

However, no bioassay data have been identified or other internal monitoring data for fission products 

until whole-body counting was fully implemented in 1970. A 1958 procedure lists gross beta urine 

analysis from Sr/Y-90, Ba/La-140, Ce/Pr-144, Sr-89, and gross fission products. This might be the 

same as the procedure referenced in 1947; no sensitivity is listed. According to the procedure, 

background was counted before and after each sample. Non-specific sensitivities of 50 to 100 dpm/L 

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with an investigation level of >200 dpm/L have been found. A similar procedure of oxalate coprecipitation and beta counting, effective in 1974, lists a sensitivity of 1 to 2 dps/L and an MDA of 25 

pCi/L. This procedure might have been effective as early as 1950. No further mention of a gross 

fission product procedure has been found, nor any associated data. However, a gamma spectroscopy 

procedure for Cs-137 in urine lists an effective date of May 1965 and an MDA of 100 pCi/L. 

The abundances of all the fission products, in relation to each other, varied considerably. Certain 

reactors at LANL operated only briefly. Some exposures are known to have occurred during reactor 

operations when gas lines and related systems leaked, and also were possible during decommissioning 

operations, weapons testing, and spent fuel evaluation. No discussions are available for interpreting 

fission product mixtures. Interviews with current and past LANL personnel involved with bioassay 

indicate that fission products were not considered a significant source term for intake among LANL 

workers. However, site reports contain references to high airborne fission product concentrations. 

(LASL HD, 1951) 

During the late 1940s and early 1950s, atmospheric testing of nuclear weapons was still on-going. 

After such tests in Nevada in the 1950s, the environmental background radiation in Los Alamos was 

as high as 5 mR/hr from fresh fission products. As discussed above and also in ORAUT-TKBS00010-5, a method for measuring gross beta activity in urine had been developed. These data have 

not been located; therefore, there is no means for reconstructing with sufficient accuracy the internal 

dose contribution from fission and activation products. Whole body counting was initiated in 1955; 

however, no data have been found prior to the 1970s. Without gross beta urinalysis or whole-body 

counting results, an individual MFP and MAP dose cannot be reconstructed with sufficient accuracy 

for members of the NIOSH-proposed class prior to 1975. After 1970, whole-body-counting data has 

been determined to be insufficient for developing a co-worker data set. 

Strontium-90 

Records of routine or special Sr-90 urinalyses are very sparse. The historical compilations of 

procedures do not specify a Sr-90 urinalysis procedure. It appears that any record of Sr-90 analysis 

actually indicates that LANL performed a gross beta analysis or sent a sample to an outside 

laboratory. Sr-90 dose currently can be reconstructed only when Sr-90 results are actually listed for 

an individual. Estimates of the total Sr-90 source term from the RaLa program ranged from several 

hundred millicuries to 40 curies (Bayo). There are no data available that permits internal dose 

contributions from Sr-90 to be reconstructed with sufficient accuracy. 

Polonium 

Work with Po-210 was of a limited scope at LANL, consisting of initiator construction with usage 

levels ranging from 100 Ci/month to 500 Ci/month. Initiator work was performed from 1945 until 

1959. After 1959, Po-210 was encountered only in the form of sealed Po-Be sources. 

Initially, the urine bioassay analysis procedure could not distinguish adequately between plutonium 

and polonium. During 1944, the total alpha results were assigned to either plutonium or polonium 

based on the individual’s work history. The procedure was modified in the fall of 1944 to extract the 

plutonium. Data are available in the Los Alamos Bioassay Data Repository database. Internal 

polonium doses can be reconstructed for monitored individuals after 1944. The analysis of co-worker 

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data provided in ORAUT-OTIB-0062 (draft) found sufficient data to allow reconstruction of the 

bounding (maximum) dose from Po-210 for unmonitored workers from 1947 to 1956. 

Other Radionuclides 

LANL has always been a center for research. As such, small-scale use of various radionuclides not 

addressed above has occurred throughout the history of LANL (“small-scale” as in number of persons 

or activity of the source). Little or no documentation has been found on bioassay for these nuclides, 

which included: Ac-227, P-32, C-14, Cm-244, Th-232, Th-230, and Pa-231. Even so, most of these 

radionuclides received considerable discussion in monthly reports. From these discussions, it can be 

surmised that, during some periods, these radionuclide represented significant source terms. Such 

discussions addressed the need for bioassay, listing of these radionuclides as significant environmental 

effluents, and identification of the lack of monitoring as an assessment finding. Th-230 may have 

been present as a natural component of uranium. Th-232 is believed to have been a significant source 

term during intermittent time periods. No monitoring results have been found for these radionuclides 

from 1943 to 1950, which would imply that isotopic techniques were either not available or not 

implemented. It can be assumed that the alpha emitters (Th-232, Cm-244, and Pa-231), if present, 

would be included in the total alpha urinalysis and attributed to either polonium or plutonium. After 

1970, with the onset of chest counting and improved analytical capabilities, LANL possessed the 

ability to monitor for all ROCs with the exception of Ac-227, Cm-244, and Pa-231. Ac-227 and Pa231 possibly could be quantified by the chest count procedure. However, no information has been 

found that would indicate an attempt at this process or that any such data are available. Inventory 

records to establish the significance of the source term of these “exotic” radionuclides is limited. 

Most available information is limited to waste activity reports. 

7.2.1.2 Lung Counting Information and Available Data 

Two sources of in vivo data were located, although they undoubtedly arose from the same database: 

1.	 In vivo data from 1965 to 1988 are available from a Microsoft Access database named “LANLBioassay Co-Worker Data-Complete” (ORAUT-OTIB-0063, draft). The database contains 

approximately 100,000 records consisting mostly of chest or whole-body measurements, although 

a few counts of specific organs or body regions can also be found. Data for Pu-238, Pu-239, 

Am-241, and Cs-137 are available. Few data for other radionuclides are available prior to the 

1980s when the use of germanium detectors became more common. Data through 1975 are 

insufficient for developing co-worker data for MFP/MAP. 

2.	 The “LAMULW02 Working Data” file set was prepared by LANL for epidemiological studies for 

workers from 1944 to 1978. This database was queried by the NIOSH Task 5 Coworker Team to 

provide specific information. (http://cedr.lbl.gov/cgi-bin/spiface/find/cedrdfs/def?DATASET= 

lamulw02). The LACFILE file contains estimated plutonium whole-body burdens as of January 1, 

1987. There are 16,315 records. Results are given separately for Pu-238 and Pu-239. 

In vivo counting equipment and techniques were developed in the late 1950s and have been in routine 

use for measuring X-ray and gamma-ray-emitting radionuclides since 1970, and possibly as early as 

1960. There is some indication that some of the counts recorded between the beginning of the 

program (in 1955) and the 1960s were for program development rather than actual suspected intakes. 

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Whole-body and Chest Counters 

The first whole-body counter to be used at LASL was the HUMCO I. This “human counter” became 

operational in 1955. The counter consisted of a large double cylinder with a liquid scintillation fluid 

(possibly trichloroethylene) filling the annular space between the cylinders. The scintillation fluid 

was viewed with an array of 5-in. photomultiplier tubes on the outside wall of the cylinder. The 

system was not used for photons below 100 keV. This system was used to screen individuals who 

might have been exposed to fission products at the reactors or in flyovers during weapons testing. It 

was also used to detect the Bremsstrahlung from Sr-90 intakes. The energy resolution of these 

counters was poor. When an elevation of the background in a region of interest was observed, the 

individual was referred for screening with either the shadow shield or full shield 4- by 8–in. NaI(Tl) 

crystals. The sensitivities of the NaI(Tl) crystal were approximately the same as those for the 

HUMCO, except the count time was significantly longer. 

The HUMCO II became operational in 1958. The HUMCO II was housed in a count room (SB-16) 

made of 7 inches of pre-World War II steel. The resolution was improved, but it remained a screening 

counter. Whole-body counting data are available for monitored employees for the dates indicated in 

the discussion above. Co-worker data are insufficient to permit the estimation of internal dose to 

unmonitored employees. 

An in vivo counter capable of measuring four separate regions of the body began operation in 1970. 

Twin Phoswich (CsI and NaI) detectors were placed over the lungs. The two layers of the detector 

were capable of simultaneously (yet separately) monitoring chest burdens for 10- to 250-keV photons 

(NaI), for plutonium and uranium isotopes and Am-241, and 200 to 2,000 keV photons (CsI) for a 

qualitative assessment of a variety of fission and activation nuclides. A planar Hyper Pure 

Germanium (HPGe) detector monitored the region between 10 and 250 keV with excellent energy 

resolution and could be positioned over the liver or thyroid, as needed. Finally, a HPGe (formerly a 

GeLi) detector was positioned under the prone subject. This detector was primarily for whole-body 

assessment. This system could both identify radionuclides and quantify the burdens. 

7.2.1.3 Other Types of Bioassay/Workplace Indicators 

Nasal Swipes 

Nasal swipe data can be found in LABFILE 1, LABFILE2, and LABFILE3 records for 1944. Until 

the first urine bioassay analysis was perfected and available in February 1945, “nose counts” were 

relied on as a qualitative indicator of plutonium intake. After the development of urine bioassay 

techniques, nasal swipes were used to indicate the need for follow-up bioassay, although bioassay was 

not always performed immediately following a positive nasal swipe. The MPL was 50 dpm, alpha, 

per nostril. In addition, in 1944 LASL adopted a policy that if the two nasal counts varied 

significantly, the higher nasal count was considered spurious. Information concerning a positive nasal 

swipe can often be found in the incident line of the Microsoft Access “LANL Co-Worker Data-Rev1” database entry for the individual (ORAUT-TKBS-0010-5). Nasal swipe results in a case file, 

although not used specifically to reconstruct dose, may provide positive indications that a potential 

uptake occurred that should be accounted for during dose reconstruction. 

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Wound Counts 

Wound count and accident data involving potential plutonium uptake can be found in LABFILE 1, 

LABFILE2, and LABFILE3 records for 1944. In August 1959, the H-6 Group acquired a probe to be 

used to monitor wounds contaminated with plutonium. Wound counting was used primarily as a tool 

for surgeons to locate plutonium in the wound, not as results used to calculate internal dose. Wound 

monitoring continues to be performed. In most cases, intake and dose will not be assessed directly 

from the wound count but rather from the resultant urine bioassay data. Follow-up studies of wounds 

found that, in the majority of incidents, plutonium does not readily migrate from the wound site to 

uptake. No other information on instrumentation or sensitivities is available (ORAUT-TKBS-0010­

5). Wound count results in a case file, although not used specifically to reconstruct dose, may provide 

positive indications that a potential uptake occurred that should be accounted for during dose 

reconstruction. 

7.2.1.4 Airborne Levels 

Maximum and average airborne concentrations can be helpful in establishing boundary conditions for 

intakes. Maximum and average airborne contamination levels in buildings with high-exposure 

potential are listed in Table 5-20 in ORAUT-TKBS-0010-5 and are summarized herein in Table 6-1. 

Airborne concentrations are available for some years of operation, but are deficient for all ROCs. The 

recently-obtained additional monitoring records may serve to better define and bound exposure 

conditions. Average concentrations are calculated from general air samples as simple averages or 

averages obtained directly from LASL reports. Blanks in the table indicate that no information is 

currently available for that period (ORAUT-TKBS-0010-5). Limited environmental air monitoring 

data are available for the period prior to 1971; air sampling began in 1944. Although the data 

available for the earlier years are incomplete and not radionuclide-specific, they may provide a 

mechanism for establishing bounding conditions. With area and environmental monitoring data 

missing for some time periods and deficient for all ROCs, a complete assessment of potential dose 

cannot be performed without the use of unsubstantiated assumptions. The data that are available, 

together with the application of dose-maximizing approaches provided in the Project’s technical 

information bulletins, will only provide a mechanism for partial estimations of worker intakes for 

those buildings, time periods, and radionuclides for which data are available. 

7.2.1.5 Radon 

A search of the Site Description (ORAUT-TKBS-0010-2) and Occupational Internal Dose (ORAUTTKBS-0010-5) TBDs found only two references to radon. In TA-1 and Buildings O and Q, the 

presence of radon is reported in relation to the use, preparation, or failure of radium calibration 

sources or radium-beryllium neutron sources. In addition, Health Division Reports for 1947 and 1951 

reference air monitoring and breath sampling for radon related to a radium storage vault and the 

resultant installation of a vent (LASL HD, 1947 and 1951). However, results of these analyses are not 

available. 

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7.2.1.6 Application of Co-Worker Data for Internal Dose Reconstruction 

A draft technical information bulletin (ORAUT-OTIB-0062, draft) has been developed for dose 

reconstruction using co-worker data for specific radionuclides during discrete time periods. The 

intake rates provided in the OTIB cover the following radionuclides and time periods: 

• Plutonium-239: 1/1/1945 through 12/31/1988 

• Plutonium-238: 1/1/1968 through 12/31/1988 

• Uranium: 1/1/1950 through 12/31/1988 

• Tritium: 1/1/1950 through 12/31/1988 

• Polonium: 1/1/1947 through 12/31/1956 

• Cesium: 1/1/1970 through 12/31/1988 

7.2.2 Ambient Environmental Internal Radiation Doses at LANL 

The Technical Basis Document for Environmental Occupational dose for the LANL Site Profile 

(ORAUT-TKBS-0010-4) lists relevant monitoring or other data pertinent to estimating environmental 

internal dose. No data were provided for years prior to 1970 that would allow dose reconstruction. 

From 1970 through 1975, a substantial amount of data is provided for several ROCs in each of the 

TAs. However, gaps exist for specific radionuclides and periods of time. It is possible that the data 

gaps for certain radionuclides may be filled by assuming or calculating a ratio to others for which data 

exist. The feasibility of such an analysis has not been investigated because no developed and 

approved methodology exists at this time. 

7.2.3 Internal Dose Reconstruction 

There are numerous scenarios involved with the SEC-00051 petition that must be independently 

evaluated prior to determining if the internal dose for each scenario can be reconstructed using 

assumptions that are favorable to the claimant. These scenarios are a result of the broad historical 

timeframe of the site, the multiple monitoring programs in place over the timeframe under evaluation, 

and multiple ROCs. Table 7-7 provides 24 combinations of worker categories and ROCs. The time 

span of each category loosely coincides with the implementation of monitoring programs for the 

major ROCs identified in site historical documents, or summaries provided in the LANL Site Profile 

(ORAUT-TKBS-0010) and the draft technical information bulletin ORAUT-OTIB-0062 (draft). It is 

critical to note that many of the following internal dose reconstruction scenario discussions rely on the 

analysis and on-going development of co-worker data sets for various ROCs. Draft ORAUT-OTIB0062 provides co-worker in vitro and/or in vivo data analyses and intake modeling for only the 

following radionuclides for the date ranges discussed below: H-3, Pu-239, Pu-238, Po-210, U, and Cs137. 

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NOTE:	 The determination whether claimant-favorable estimates of potential internal dose can be 

performed for each worker category/ROC combination is discussed in turn. In the 

discussions below, the numbers to the left refer to the corresponding scenario number in the 

Table 7-7 cells. 

Table 7-7: LANL Internal Dose Scenarios by Worker Category and ROCs 

Worker Category 

Internal Dose Radionuclides of Concern (ROCs) 

Uranium Plutonium Tritium 

Fission Products/ 

Misc. Transuranics/ 

Thorium /210Po /241Am 

Monitored/ Terminated Pre19501 1 2 3 4 

Unmonitored/ Terminated 

Pre-19502 5 6 7 8 

Monitored/Employed 1950 

through 19691 9 10 11 12 

Unmonitored/Employed 

1950 through 19692 13 14 15 16 

Monitored/Employed 1970 

through 19751 

17 18 19 20 

Unmonitored/Employed 

1970 through 19752 21 22 23 24 

Notes: 1 The monitored category represents those workers who were radiologically monitored, or those who should have been 

monitored (by then-current monitoring standards). 

2 The unmonitored category represents those workers who were not radiologically monitored because they worked in 

areas with low exposure potentials by then-current monitoring standards (i.e., exposure scenarios in which ambient 

environmental dose was typically assigned). 

Monitored/Terminated Pre-1950 

Only workers perceived to be at risk, or those involved in incidents, submitted samples for bioassay. 

Also, workers assigned to temporary assignments may not have been required to submit a sample 

regardless of the exposure potential (i.e., worked in areas where they should have been monitored). 

1) Uranium: Uranium may have been the primary ROC prior to 1950, and certainly prior to 1945 

when significant (kilogram) quantities of plutonium arrived on site. Monitoring for uranium 

consisted of routine urinalysis starting in 1949 for employees identified as being at risk for 

exposure (ORAUT-TKBS-0010-5, Table 5A-14). Nasal swipes with more than 50 cpm 

indicated the need for follow-up bioassay. Contributions to internal dose from uranium 

intakes to workers for TAs where uranium was handled can be reconstructed using the 

unmonitored worker methodology described in Section 5.6 of ORAUT-TKBS-0010-5 (prior to 

the advent of the uranium bioassay program in 1949). This approach recommends estimating 

hypothetical intake rates for workers based on either the average or maximum enriched 

uranium air sampling data from the DP East site. As bioassay monitoring data are available 

after 1949, internal uranium doses can be reconstructed for the period after 1949 using the 

inferred isotopic fractions and described methodology in Section 5.2.4 of ORAUT-TKBS83 of 117 
 

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0010-5. Other information useful to dose reconstruction (i.e., solubility fraction, analytical 

methods, MDAs, co-worker data, etc.) can be found in ORAUT-TKBS-0010-5 and draft 

ORAUT-OTIB-0062. 

2) Plutonium: Only milligram quantities of plutonium existed in 1943, but this amount increased 

to kilograms by 1945. A routine urinalysis program was implemented in 1944 but not 

perfected until 1945. For workers in TAs where plutonium was handled and who may have 

terminated employment prior to the onset of routine bioassays, the plutonium contribution to 

internal dose could be reconstructed by using the unmonitored worker methodology described 

in Section 5.6 of ORAUT-TKBS-0010-5. This approach recommends estimating hypothetical 

intake rates for workers based on either the average or maximum plutonium air sampling data 

from Building D. Data are available and internal plutonium doses can be reconstructed for the 

period after 1945. However, the plutonium isotopic distribution is not available and early 

results are reported as plutonium or Pu-239. For dose reconstruction, the values should be 

considered total plutonium alpha counts, which would include Pu-239, Pu-240, and Pu-238. 

Data providing the nominal isotopic distribution for weapons-grade plutonium are available in 

ORAUT-TKBS-0010-5. Co-worker data and intake modeling beginning in 1945 are provided 

in draft ORAUT-OTIB-0062. 

3) Tritium: Site documents indicate operation of an accelerator, a Van de Graaff generator, and 

other operations during this timeframe that may have been sources of tritium exposure. In 

addition, tritium was used in TA-1 as early as 1946. There are no records of tritium 

monitoring prior to 1950. Tritium contributions to internal dose to workers in applicable TAs 

cannot be reconstructed prior to this time because available Project technical information 

bulletins do not provide a method for estimating the maximum plausible tritium contribution to 

internal dose. 

4) Mixed Fission Products/Mixed Activation Products: Historical documentation indicates the 

implementation in 1947 of a gross-beta-in-urine analysis for mixed fission products 

(MFP)/mixed activation products (MAP). These materials would have been present in TAs 

associated with reactors, spent fuel handling, accelerators, and residual contamination in 

RaLa-associated TAs. However, bioassay records for these radionuclide analyses are not 

available. This, combined with the lack of air monitoring data available at the time of this 

evaluation, precludes reconstruction of internal doses from MFP/MAP during this time period. 

Recently-obtained records may permit future maximizing-dose reconstructions for specific 

areas for which air limited monitoring data records have now been identified. 

Americium: Am-241 is a contaminant in aged weapons-grade plutonium. The fraction of the 

total alpha activity is small, typically less than 10%. Pure Am-241 was used for various 

purposes at LANL, including the manufacture of Am-Be sources. However, it can be 

reasonably assumed that exposure to pure Am-241 was unlikely prior to full implementation of 

the americium bioassay program in 1954, which coincides with the beginning of work with 

pure sources of Am-241. Prior to this time, little Am-241 monitoring data have been 

identified; recently-obtained data show an earliest date of 1949. If plutonium bioassay data are 

available, a claimant-favorable value for Am-241 can be inferred from nominal isotopic 

fraction values found in ORAUT-TKBS-0010-5. The maximum dose from unmonitored Am241 intakes associated with plutonium operations can be reconstructed if associated plutonium 

data are available from individual records or co-worker data. Other bounding-exposure 

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scenarios may be possible by applying monitored worker data discussed above that include 

doses from unmonitored intakes of Am-241 associated with plutonium exposure, or by using 

methods described in ORAUT-TKBS-0010-5. 

Polonium: Work with Po-210 was of limited scope and duration from 1944 to 1959, primarily 

consisting of construction of nuclear weapon initiators. Personnel monitoring was performed 

for the entire duration. The urinalysis method during 1944 could not distinguish between 

plutonium and polonium so the results were assigned based on the individual’s work history. 

(Note: This approach has some validity because during 1944 there was a limited quantity of 

plutonium and work was restricted to specific facilities). From 1944 onward, plutonium was 

extracted from urine samples prior to counting. Claimant-favorable conditions are provided in 

ORAUT-TKBS-0010-5 when estimating internal monitored or missed dose from polonium. 

The analysis of co-worker data being developed for ORAUT-OTIB-0062 (draft) should allow 

reconstruction of the bounding (maximum) dose from Po-210 from 1950 to 1956 for workers 

who should have been monitored but were not. There is a gap in co-worker data from 1956 to 

1959 (when polonium operations ceased). However, if it is assumed that routine operations 

were consistent from year to year, the co-worker information may possibly be extrapolated. 

Co-worker data and intake modeling beginning in 1947 are provided in draft ORAUT-OTIB0062. 

Thorium, Actinium, Curium, Protactinium: There are numerous references in Health Division 

reports to the use of and monitoring for these radionuclides. However, specific information on 

processes and quantities is not available. Th-230 may have been present as a natural 

component of uranium. There is a listing for a procedure for Th-230 noted in 1958, but no 

monitoring data has been identified to support this. No monitoring results have been found for 

the remaining radionuclides (Th-232, Cm-244, and Pa-231) from 1943 to 1950, which would 

suggest that isotopic techniques were either not available or not implemented. Should betaemitter urinalysis data be identified in the future, Ac-227 activity would be included in the 

total beta urinalysis and be attributed to mixed fission product beta (Sr-90/Y-90) which would 

again be non-conservative. ORAUT-TKBS-0010-05 mentions that one notebook was found 

containing 15 bioassay results for actinium. 

Unmonitored/Terminated Pre-1950 

Workers who were not perceived to be at risk or were not involved in incidents were not monitored 

(because they worked in areas with low exposure potentials by then-current monitoring standards (i.e., 

exposure scenarios in which ambient environmental dose was typically assigned). 

5–7) Uranium, Plutonium, Tritium: The optimum source of data to estimate doses to this category 

of unmonitored workers is dose from ambient environmental exposures. In the absence of 

ambient environmental exposure data, bounding exposure scenarios may be possible by 

applying monitored worker data that include co-worker data analyzed per ORAUT-OTIB-0019 

(which has been performed and documented in ORAUT-OTIB-0062 [draft]) or by using 

methods described in ORAUT-TKBS-0010-5. 

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8)	 Polonium: The optimum source of data to estimate doses to this category of unmonitored 

workers is dose from ambient environmental exposures. In the absence of ambient 

environmental exposure data, bounding exposure scenarios may be possible through the 

application of monitored worker data which include the analysis of co-worker data provided in 

ORAUT-OTIB-0062 (draft) (to bound dose from Po-210 from 1947 to 1950) or methods 

described in ORAUT-TKBS-0010-5. 

Americium: The optimum source of data to estimate doses to this category of unmonitored 

workers is dose from ambient environmental exposures. Available data are insufficient. In the 

absence of ambient environmental exposure data, bounding exposure scenarios may be 

possible through the application of monitored worker data which include doses from 

unmonitored intakes of Am-241 associated with plutonium exposure or methods described in 

ORAUT-TKBS-0010-5. 

MFP/MAP, Th-232, Th-230, Ac-227, Pa-231: Insufficient coworker data were available for 

dose reconstruction for MFP/MAP, Th-232, Th-230, Ac-227, or Pa-231. 

Monitored/Employed 1950 through 1969 

Only workers perceived to be at risk, or those involved in incidents, submitted samples for bioassay. 

Also, workers assigned to temporary assignments may not have been required to submit a sample 

regardless of the exposure potential (i.e., worked in areas where they should have been monitored). 

9-11)	 Uranium, Plutonium, Tritium: As noted, urinalyses for uranium, plutonium, and tritium have 

been performed during this entire period. In addition, plutonium bioassay data from 1968 on 

may be reported as Pu-238 or Pu-239. Pu-238 results reflect employees involved in the 

production of radioisotope power-generation devices. Data sufficient to reconstruct the dose 

from these radionuclides are reported in ORAUT-TKBS-0010-5. 

12) Mixed fission Products/Mixed Activation Products: There were no analytical techniques in use 

prior to 1955 that would provide an isotopic result for MFP/MAP activity. According to 

ORAUT-TKBS-00010-5, a method for measuring gross beta activity in urine had been 

developed. If these results are available, the maximum dose from MFP/MAP might be 

estimated by assuming all beta activity consists of Sr/Y-90. At the time of this report, this 

assumption has not been validated. Whole body counting was initiated in 1955. If these 

results are available, they can be used to estimate the dose for gamma-emitting species for 

monitored individuals. If neither gross beta urinalysis nor whole-body counting results are 

available, a claimant’s dose cannot be reconstructed. 

Americium: Prior to 1954, little bioassay was identified for Am-241; recently-obtained data 

show an earliest date of 1949. As noted, the dose from americium may be bounded by using a 

conservative ratio to plutonium, if those data exist. After 1954, bioassay results should be 

available for monitored employees but are likely to reflect operations using “pure” Am-241 

and should be added to Am-241 associated with plutonium results, as described previously. 

The data available for the years between 1949 and 1954 require validation, review, and 

incorporation into the project database. 

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Polonium: As stated above, analysis for polonium in urine was initiated in 1944. From 1944 

until 1945, bioassay counts were attributed based on job assignment since the technique could 

not distinguish between polonium and plutonium. The use of polonium ceased in 1959, with 

the exception of sealed sources. The possibility of a polonium intake after this date is remote. 

Thorium, Actinium, Curium, Neptunium, Protactinium: There are numerous references in site 

documentation regarding the use of these radionuclides as well as the apparent absence or 

unsuccessful development of a bioassay program (see Section 7.4.3). These references began 

in the early 1950s and remained a concern through the early 1990s. Evidence of this latter 

concern was included as a finding in the DOE Tiger Team Report for LANL (Tiger Team, 

1991), as follows: 

Personnel of the Isotope and Structural Chemistry Group, the Ceramic Science and 

Technology Group working with Th-232 and its decay products during chemistry 

operations in TA-21 and TA-3 Building SM-66 are not enrolled in the bioassay 

program of assessment of potential internal exposures. Line managers were not 

aware that thorium and its decay products were internal hazards and that workers 

handling gram quantities of dispersible thorium oxide powders...should be identified 

for participation in the bioassay program. 

Furthermore, no records have been identified that specifically identify forms, quantities, or 

processes for which these various radioactive materials were used during the evaluation 

period. Th-230 may have been present as a natural component of uranium. No monitoring 

results have been found for the remaining radionuclides (Th232, Cm-244, and Pa-231), which 

would suggest that isotopic techniques were either not available or not implemented. Should 

beta-emitter urinalysis data be identified in the future, Ac227 activity would be included in the 

total beta urinalysis and be attributed to mixed fission product beta (Sr-90/Y-90) which would 

again be nonconservative. ORAUT-TKBS-0010-05 mentions that one notebook was found 

containing 15 bioassay results for actinium. See the discussion under Scenario 4 above. Note: 

Although neptunium is not specifically discussed in Scenario 4, the conclusion therein is 

applicable for Np-237. 

Unmonitored/Employed 1950 through 1969 

Workers who were not perceived to be at risk, or were not involved in incidents, were not monitored 

(because they worked in areas with low exposure potentials by then-current monitoring standards (i.e., 

exposure scenarios in which ambient environmental dose was typically assigned). 

13-15) Uranium, Plutonium, Tritium: The optimum data source for estimating doses to this category 

of unmonitored workers is dose from ambient environmental exposures. In the absence of 

ambient environmental exposure data, bounding exposure scenarios may be possible through 

the application of monitored worker data which include the analysis of co-worker data 

provided in ORAUT-OTIB-0062 (draft) or methods described in ORAUT-TKBS-0010-5. 

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This analysis has been performed and documented in ORAUT-OTIB-0062 (draft) and 

provides daily intake estimates for the following radionuclides over the time periods indicated: 

• Plutonium-239: 1945 through 1975+ 

• Plutonium 238: 1968 through 1975+ 

• Uranium: 1949 through 1975+ 

• Tritium: 1950 through 1975+ 

16) Mixed Fission Products/Mixed Activation Products: Co-worker in vivo monitoring data are 

insufficient from 1970 through 1975. Before 1970, there appear to be no data other than the 

recently-identified, but limited area airborne monitoring data. 

Americium: The optimum data source for estimating doses to this category of unmonitored 

workers is dose from ambient environmental exposures. In the absence of ambient 

environmental exposure data, bounding exposure scenarios may be possible through the 

application of monitored worker data which include the analysis of co-worker data provided in 

ORAUT-OTIB-0062 (draft) or methods described in ORAUT-TKBS-0010-5. As previously 

discussed, Am-241 associated with plutonium operations can be inferred from isotopic ratios 

for weapons-grade plutonium (if plutonium bioassay results exist) using the isotopic ratios 

found in the Wingfield inventory (Wingfield, 1974). The potential dose from unmonitored 

intakes of “pure” Am-241 (after 1954 until 1970 when in vivo monitoring data are available) 

can only be reconstructed by assigning a hypothetical intake. 

Polonium: The optimum data source for estimating doses to this category of unmonitored 

workers is dose from ambient environmental exposures. In the absence of ambient 

environmental exposure data, bounding exposure scenarios may be possible through the 

application of monitored worker data which include the analysis of co-worker data provided in 

ORAUT-OTIB-0062 (draft) or methods described in ORAUT-TKBS-0010-5. The analysis of 

co-worker data provided in ORAUT-OTIB-0062 (draft) will allow reconstruction of the 

bounding (maximum) dose from Po-210 from 1947 to 1956. There is a gap in co-worker data 

from 1956 to 1959 (when polonium operations ceased). However, if it is assumed that routine 

operations were consistent from year to year, the co-worker information may possibly be 

extrapolated. At the time of this report, that analysis has not been completed. After 1959, it 

can be assumed that the chance of a polonium intake is remote, and if it occurred, a bioassay 

would have been performed. 

Thorium, Actinium, Curium, Neptunium, Protactinium: See the discussion under Scenario 12 

above. 

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Monitored/Employed 1970 through 1975 

Only workers perceived to be at risk, or those involved in incidents, submitted samples for bioassay. 

Also, workers assigned to temporary assignments may not have been required to submit a sample 

regardless of the exposure potential (i.e., worked in areas where they should have been monitored). 

17–20) Uranium, Plutonium, Tritium, MFP/MAP: After 1970, with the onset of chest counting and 

improved analytical capabilities, LANL possessed the ability to monitor for all ROCs with the 

exception of Ac-227, Cm-244, and Pa-231. Ac-227 and Pa-231 possibly could be quantified 

by the chest count procedure. However, no information has been found that would indicate an 

attempt at this process. 

Unmonitored/Employed 1970 through 1975 

Workers who were not perceived to be at risk, or were not involved in incidents, were not monitored 

(because they worked in areas with low exposure potentials by then-current monitoring standards (i.e., 

exposure scenarios in which ambient environmental dose was typically assigned). 

21-24) Uranium, Plutonium, Tritium, MFP/MAP: Doses can be reconstructed from co-worker data for 

the following ROCs from 1970 on: Pu-238, Pu-239, uranium, and tritium (significant 

operations involving polonium ceased in 1959). 

Americium: The maximum dose from unmonitored Am-241 intakes can be reconstructed if 

associated plutonium data are available, and for pure sources, by evaluating the in vivo chest 

count data. See the discussion under Scenario 16 above. 

Thorium, Actinium, Curium, Neptunium, Protactinium: See the discussion under Scenario 4 

above. 

7.2.4 Internal Dose Reconstruction Feasibility Conclusion 

Through December 2006, 657 EEOICPA claims from LANL workers with employment dates 

between March 15, 1943 and December 31, 1975 had been submitted to NIOSH. Of those 657 

claims, dose reconstructions have been completed for 300 claims, and three claims are awaiting a 

response to NIOSH’s request for monitoring data. These claims cover the entire range of the LANL 

evaluation period in this report and include claims with internal monitoring data. There are 384 

claims with hire dates within the petition timeframe that have internal monitoring data available: five 

have data between 1943 and 1945, 68 have data between 1946 and 1950, and 308 have data between 

1951 and 1975. 

Based on the information provided in the previous discussion, the dose from intakes cannot be 

reconstructed for specific radionuclides for varying periods spanning a significant percentage of the 

period from 1943 to 1975. Since information on a claimant’s exact work location is rare, it will be 

necessary in most cases to assume exposure to all ROCs. For these reasons, dose reconstructors will 

be unable to provide an estimate of a claimant’s maximum internal dose for this period. The dose 

from exposure to some of the major ROCs (H-3, Pu-239, Pu-238, Po-210, U, and Cs-137).can be 

reconstructed for the majority of the time period using co-worker data or other assumptions. The 

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exceptions are Am-241 from operations involving “pure” sources which started in 1954 (although this 

conclusion may be altered based on the newly-identified data), MFP/MAP, Th-230, Th-232, Ac-227, 

Cm-244, Np-237, and Pa-231. At this point, the cumulative effect of the doses from these ROCs must 

be considered significant. This conclusion is based on the reporting of these radionuclides in effluent 

release and waste records as well as various other documents discussed throughout this evaluation. 

With no information to the contrary, and to be claimant-favorable, it must be assumed that doses from 

these radionuclides are not negligible. This could lead to the conclusion that major components of the 

potential dose cannot be reconstructed over the entire period of interest (1943 to 1975). 

Table 7-8 presents a summary of the data deficiencies listed by period and radionuclide. 

Table 7-8: Summary of LANL Data Deficiencies 

Period Radionuclides with No Reconstruction Data or Method 

1943 -1949 Tritium, MFP/MAP, Am-241 (if no Pu data and pending validation of newly-identified bioassay 

data), Th-232, Th-230, Ac-227, Pa-231, and Cm-244. 

1950 - 1969 MFP/MAP, (without the validation of the newly-identified air monitoring data), Am-241 (if no Pu 

data or from “pure” process), Th-232, Th-230, Ac-227, Pa-231, Np-237, and Cm-244. 

1970 – 19751 MFP/MAP, Am-241 (if no Pu data or from “pure” process), Th-232, Th-230, Ac-227, Pa-231, Np237, and Cm-244. 

1

 Some radionuclide maximum intakes possibly could be inferred from the chest counting data. However, at the time of 

this report, an analysis of this technique has not been performed. This technique most likely could not be used for Cm-244 

due to the 18.7 y half-life and with only a 10% yield 14 keV X-ray. References to direct work with Cm end in 1975, other 

than burial grounds and minor residual contamination in TA-1 Building 3 and ML. 

7.3 External Radiation Doses at LANL 

The principal sources of external radiation doses for members of the proposed class were exposures to 

photon, neutron, and beta radiations (ORAUT-TKBS-0010-6). The radiation sources contributing to 

external doses were: 

•	 Reactors/accelerators/X-ray-generating equipment/criticality facilities (gamma, X-ray, neutron, 

and beta radiation) 

•	 Plutonium chemistry and metallurgy (gamma and neutron radiation) 

•	 Uranium chemistry, metallurgy, machining, and testing applications (gamma and beta radiation) 

•	 Initiators (neutron radiation) 

•	 RaLa (photon and beta radiation) 

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• Spent fuel or waste handling and processing (gamma and beta radiation) 

• Calibration and other miscellaneous sources (gamma, neutron, and beta radiation) 

• Periodic medical examinations (X-ray radiation) 

7.3.1 Process-Related External Radiation Doses at LANL 

The following subsections summarize the extent and limitations of information available for 

reconstructing the process-related external doses of members of the proposed class. 

7.3.1.1 Radiation Exposure Environment 

The diverse nature of the LANL mission resulted in innumerable external exposure environments 

ranging from low-energy photons shielded by dry boxes in the plutonium operations, to full 

immersion in beta-gamma fields from reactor gas line leaks, direct exposure to X-ray and accelerator 

beams, and criticality neutron bursts. In the reactor, accelerator, X-ray-generating, radiography, and 

criticality facilities, exposures were possible from gamma, X-ray, neutron, and beta (or electron) 

radiations. 

Operating reactors were a source of gamma, beta, and neutron radiation. Exposures during operation 

were possible from: mixed fission and activation products present in systems, system leaks that 

periodically developed, off-gas systems, and activated components; and to neutrons from core leakage 

or from neutron beam ports. Exposures to beta-gamma radiation from mixed fission and activation 

products present in reactor components and systems, wastes, and spent fuel were possible when 

reactors were in shutdown mode, during spent fuel handling and evaluation, waste handling, or during 

decommissioning. TA-2 (Omega Site) was the primary reactor technical area. Other reactor areas 

included the Project Rover Kiwi Reactors developed in TA-18, the Molten Plutonium and Power 

Reactor experiments in TA-35, and the UHTREX Reactor in TA-52. 

External exposures from accelerators were from neutrons, electrons, and X-rays while the beam was 

operating, and mixed air activation products and activation products in the target and accelerator 

structure both during operation and after the beam was shut down. The highest external dose rates 

would be directly in the beam path. Typically, there would be varying degrees of access controls in 

place (from warning lights to automatic interlocks) to warn or prevent personnel from entering the 

unit while the beam was operating. There were multiple accelerators at LANL located in TA-1, -3, 

and -53. 

Radiation from X-ray and radiography equipment would have consisted primarily of photons when 

the equipment was operating or when a radiography source was raised from the source well. 

Activities involving these systems were located in TA-8, -13, -15, -16, -24, -35, and -51. 

In the plutonium processing areas of TA-1, -3, -21, and -55, the primary sources for external radiation 

exposure were low-energy photons from plutonium and Am-241, a progeny of the Pu-241 present in 

weapons-grade plutonium (WGPu). Also present were neutrons from spontaneous fission of even 

isotopes of plutonium, alpha-neutron reactions, and low abundance neutron-induced fissions. 

In the uranium chemistry, metallurgy, machining, and testing applications processing areas, the 

primary external radiation exposure concern was high-energy beta emitters from uranium progeny and 

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impurities. During processes such as melting and casting, these daughter elements may concentrate 

on the surface of the castings and equipment, producing elevated beta dose rates. Photon doses from 

uranium were typically a small fraction of the beta doses; however, storage of large amounts of 

uranium would have had associated low-level gamma radiation fields (DOE-STD-1128-98). Similar 

conditions would have also existed in areas involved with thorium. 

Initiator production primarily involved polonium-210 processing; lesser quantities of radium-226 and 

actinium-227 were also used. Gamma intensities during production of the PoBe neutron sources were 

considered very low; fast neutron exposures were considered the limiting exposure scenario. 

Therefore, after an initial film badge monitoring trial period showed no gamma exposures, workers 

discontinued wearing film badges in DP East (TA-21). 

The primary radioactive materials associated with the radioactive lanthanum (RaLa) program were 

Ba-140, La-140, Sr-89, and Sr-90 (with half-lives of 12.7 days, 1.7 days, 50.6 days, and 28.5 years, 

respectively). The evaluation report for Petition SEC-00061 extends 16 months beyond the date of 

the final RaLa implosion test. During those 16 months, the relatively short-lived radionuclides 

(Ba-140, La-140, and Sr-89) would have decayed to insignificant levels. Therefore, residual Sr-90 

(with its daughter product yttrium-90) is the only contaminant associated with the RaLa program that 

pertains to this present evaluation. Sr-90 was present as a production contaminant in the Ba/La-140 

that was processed and was distributed to the environment during the test shots. External exposure to 

these materials would be primarily from beta radiations. 

External exposures during spent fuel handling and processing (primarily fission products) or waste 

handling and processing (potentially all known radionuclides used at LANL) would have been 

primarily from gamma radiation with some potential for beta radiation. In many cases of waste 

handling, beta exposures would have been limited if the waste was containerized. Spent fuel would 

have been handled remotely due to the high radiation levels, with processing also done remotely 

within shielded hot cells. 

External exposures to gamma, beta, and neutron radiation were also possible from the handling and 

use of calibration, radiography, and other miscellaneous sources. Calibration sources would have 

included Co-60, Ra-226, Cf-252, and others for calibrating and evaluating film badge response. 

Radiography sources included curie level sources of Cs-137 and Co-60. 

Lastly, periodic medical examinations at LANL required chest X-rays on an annual or semi-annual 

basis. 

Beta and Photon Characterization 

For activities related to weapons production, including H-3 production; plutonium processing and 

production; uranium processing, machining, and test firing; and RaLa, the exposure spectrum was 

dominated by a wide energy range for beta (0.019 Mev to 2.29 MeV) and low-to-middle energy range 

for photons (<0.030 to 0.250 MeV). Higher-energy photons (>0.250 MeV) that would have been 

associated with the RaLa program are addressed in another petition (SEC-00061) and are not 

considered in this evaluation. 

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Radiations from reactor and accelerator operations would have encompassed a broad spectrum of 

energies, primarily from 0.030 to greater than 0.250 MeV for photons, but also including a lesser 

abundance of photons less than 0.250 MeV as well as beta energies greater than 0.015 MeV. 

Waste-handling spectrums are source-specific and would have encompassed the range of energies 

previously described. 

Neutron Field Characterization 

The energy spectrum encountered from reactors, accelerators, plutonium production, and calibration 

sources ranged from the thermal energy region (0.025 eV) through the fission spectrum (0.1 to 6.0 

MeV) with a predominant energy range of 0.7 to 1.0 MeV; the spectrum also included high-energy, 

accelerator-produced neutrons with energies up to 20 MeV. 

7.3.1.2 History of Whole Body External Monitoring 

The procedures for monitoring and interpreting the external exposures of LANL workers were 

continually being evaluated and refined. The initial external exposure hazards were primarily 

associated with radiation generated from the early accelerators and, to a lesser extent, uranium 

chemistry and metallurgy. Beginning in 1943, these initial exposures were monitored by PICs issued 

to individuals thought to have the highest exposure potential. The PIC exposure measurements were 

read and recorded on a daily basis. 

By mid-1944, film badges containing dental X-ray film were gradually phased in, originally as a 

means to evaluate the PIC exposure measurements. Film dosimetry started when site operations were 

expanded to include reactors, critical assemblies, expanded plutonium work and inventories, and 

chemical processing and test shots involving RaLa. These early film badges were exchanged and 

analyzed on a monthly basis and were only used to measure the photon deep dose; shallow beta 

exposure doses and neutron doses were not monitored. Although film badges were originally 

assigned to those individuals thought to have the greatest exposure potential, within three years badge 

assignments had expanded to over 1,000 workers. Following a fatal criticality accident, separate 

catastrophe badges began to be issued in 1945 to workers who could be involved in future criticalities. 

Uranium workers also may have been monitored for extremity dose with ring film badges or film 

badges within work gloves, which were later replaced by wrist film badges. 

There was no monitoring of beta shallow dose exposure prior to 1949. Early thermal neutron 

monitoring was performed until 1949 using PICs. There was no fast neutron monitoring until 1949 

when nuclear track plates began to be issued. However, a 1968 site study determined that these early 

neutron dosimeters lacked adequate neutron sensitivity to provide meaningful exposure results. 

Recognition of the energy dependence of film response to the highly-variable photon fields present 

within the various TAs, and the need to monitor beta radiation exposures, led to replacement of the 

original film badge. Unless calibrated to the photon environment in a given workplace, the 

interpretation of film badge response would result in reporting higher-than-actual whole-body 

exposures in low-energy photon fields, and lower-than-actual whole-body exposures in higher-energy 

fields. A brass clip badge capable of separating beta from gamma exposures was instituted in 1949, 

immediately followed in 1950 by a brass-lead clip film badge for differentiating various gamma 

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energies. A 1951 changeover to a brass-cadmium badge added NTA film for fast neutron dosimetry. 

The multi-element Cycolac badge was introduced in 1962 and was designed to provide gamma/X-ray, 

beta, neutron, and accident neutron dosimetry. Thermoluminescent dosimeters (TLDs) replaced the 

Cycolac badge in 1978 (after the period addressed in this evaluation). Numerous studies have been 

conducted to evaluate and account for the energy dependence of the various dosimeters, and 

ultimately how doses were reported. 

Exchange frequencies for the various badge types were typically every two to four weeks, but may 

have been more frequent, in some cases daily for operations with high exposure potential. Exchange 

frequency directly affects the minimum detection level (MDL), and hence, potential missed dose; 

shorter exchange frequencies have higher MDLs. 

LANL worker external exposure monitoring practices concentrated on those individuals or operations 

with the greatest potential for exposure. However, site documentation provides significant 

information that the enforcement of administrative monitoring procedures and requirements may have 

been inadequate during some of the time period under evaluation. Recognition of these issues was 

documented and procedural changes recommended. Relevant excerpts from various reports available 

on the site research database are provided in Section 7.4.3 below. 

7.3.1.3 History of Extremity Monitoring 

The available historical documentation indicates that extremity monitoring began in 1951 when a 

finger film badge was developed. These badges were worn directly on the hand or placed inside 

leather work gloves. Issues with discomfort while wearing the ring badges led to replacement of ring 

badges with wrist badges. Studies were performed to develop exposure dose ratios between the finger 

badges and wrist badges. Extremity badging was used for workers involved in the production of 

“urchin” type initiators and uranium metal operations. 

7.3.1.4 Neutron Dosimetry Issues and Dose Reconstruction 

Throughout LANL’s operating history, neutron dose has been a primary constituent of the collective 

site dose. However, personnel neutron monitoring was not implemented until 1949 when NTA films 

were added to film badges to monitor fast neutron exposure. Monitoring of thermal neutron exposure 

began in 1953. A series of Atomic Energy Commission workshops were held beginning in 1969 to 

address issues related to accurately measuring neutron dose at AEC facilities. Studies determined that 

neutron doses had been significantly underestimated for fast neutrons in the intermediate energy 

range. This was the result of the NTA neutron energy response threshold of 700 keV. Therefore, 

worker dosimetry worn to monitor fast neutron exposures would not have responded to neutron 

fluences below this threshold; hence, a worker’s contemporary neutron dose of record may have 

shown no exposure or been underestimated. Because of this monitoring gap, uncertainty about where 

individuals may have worked, and whether they were exposed to fluences below the threshold, 

neutron doses cannot be directly reconstructed using the neutron monitoring records or co-worker 

data. 

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7.3.1.5 Dosimetry Records 

Table 7-9 summarizes the chronological events related to types of dosimetry, methods of calculation, 

units of reporting, and record-keeping practices. 

Table 7-9: LANL Dosimetry Records Chronology 

Year Relevant Events 

1943 Monitoring for external radiation exposures begins using pocket ionization chambers (PICs); gamma 

exposures are recorded in units of roentgen (R). 

External radiation evaluation results are recorded in notebooks that eventually find their way to the 

Document Room for permanent filing (LASL PEB, 1959; 01/20/51 document). This practice continues until 

the onset of the Cardex system in 1953. 

1944 Beginning mid-year, the transition to film badge dosimetry begins; only the photon component is measured. 

1945 Film badges come into use by more and more LANL groups; only gamma exposures were evaluated (in 

roentgens). 

1946 NOTE: A NIOSH review of LANL dose reconstruction cases found that, for cases corresponding to the 

relevant timeframe, there were no external monitoring results available prior to 1946. 

1949 Sometime prior to 1949, some LANL personnel who work with the cyclotron and other neutron sources 

wear Victoreen pencil PICs to determine their neutron dose (LASL, 1969; 11/12/68 memorandum). The 

results are recorded in “n-units,” which are defined as “the quantity of neutron radiation that will produce 

the same ionization in a 100-R Victoreen chamber (red bakelite) as 1 R of gamma radiation.” NOTE: While 

“n-unit” data were recorded in medical records of some individuals, they were apparently never converted 

to the computerized database of exposure records (Widner, 2004). 

Starting in January, the following values were recorded on personnel exposure sheets: pocket ionization 

chamber readings (R), gamma exposure (R), beta exposure in roentgens equivalent physical (rep). Beta 

exposure was reported only when “it forms a significant part of the total exposure” (LASL PEB, 1959; 

01/10/49 memorandum). No entry in the beta exposure column indicated that a negligible amount of beta 

exposure was present. 

For DP Site personnel working with plutonium and for soft X-ray evaluations, special calibration curves are 

used, and gamma R exposures are multiplied by 0.6 to convert to gamma rem (LASL PEB, 1959; 07/01/56 

document). NOTE: The comparable DOELAP roentgen-to-rem dose conversion value is 0.38 for 16 keV 

photons (DOE/EH-0027). 

In August, separate Nuclear Track Plates (NTPs) come into use to monitor fast neutron exposure. 

Shallow dose exposure monitoring begins. 

The basic film badge is modified to a brass clip film badge to permit separating the beta and photon 

exposure components. 

1950 The brass clip film badge is replaced by a brass-lead clip film badge that can differentiate various gamma 

energies. 

1951 The brass-lead clip film badge is replaced by a brass-cadmium badge with Nuclear Track, Type A emulsion 

(NTA) film for fast neutron exposure monitoring. Tolerances for neutrons are stated in terms of neutrons 

cm-2 sec-1 (LASL PEB, 1959; Jan. 1953 document). NOTE: It was determined in the late 1960s that the 

neutron monitoring performed using NTA film from 1951 up until that time was not adequate. 

1952 In uranium areas (e.g., foundry, HT shop, Sigma area), only beta exposures are directly monitored; this 

practice continues until 1956. NOTE: Some gamma exposures should have been recorded for workers at 

those facilities (LASL PEB, 1959; 04/03/57 document). 

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Table 7-9: LANL Dosimetry Records Chronology 

Year Relevant Events 

1953 In January, a “Cardex” system for filing exposure data on paper cards is put into use (LASL PEB, 1959; 

02/16/56 memorandum). Only plates that are "read" are recorded (LASL PEB, 1959; 02/27/56 document). 

Neutron doses are reported in terms of rem. NOTE: This practice possibly occurs before 1953 (LASL PEB, 

1959; Jan. 1953 document). It was determined in the late 1960s that the neutron monitoring performed 

using NTA film from 1951 up until that time was not adequate. 

1956 In January, LANL starts noting all issued NTPs on Personnel Exposure Cardex records. As of February, 

NTPs are evaluated by assuming that all 10-100 micron tracks represented 3.75 MeV neutrons, and that all 

longer tracks represent the maximum average energy of the higher-energy neutrons in the workplace. 

NOTE: It was determined in the late 1960s that the neutron monitoring performed using NTA film from 

1951 up until that time was not adequate. 

Beta and gamma exposures are now directly monitored in uranium areas. 

1957 A computerized IBM system is first employed to record personnel exposures to radiation (LASL PEB, 1959; 

04/3/57 memorandum). 

To convert radiation exposure records for IBM entry, gamma exposure was retrospectively calculated from 

the gamma-plus-beta exposure dosimetry values by using a factor of 1/10 of the total exposure measured. 

The theoretical ratio of gamma to beta plus gamma is reported to be about 1/17 for normal uranium. 

In July, the roentgen-to-rem dose conversion factor is changed to 0.5 for body badges exposed to lowenergy X-rays and plutonium; this practice continues until 1963 (LASL, 1969; 03/20/63 memorandum). 

1959 IBM equipment is first used to evaluate film exposures (Littlejohn, 1960). NOTE: Record-keeping has been 

computerized ever since. 

1960 Thermal neutron monitoring begins. 

The following external radiation dose data are recorded (Littlejohn, 1960): gamma dose (rem), beta dose 

(rad), thermal neutron dose (from cadmium optical density minus brass optical density, rem), fast neutron 

dose (from NTA film, rem). NOTE: It was determined in the late 1960s that the neutron monitoring 

performed up until that time was not adequate. 

1962 The brass-cadmium film badge is replaced by the multi-element Cycolac badge. The Cycolac is designed to 

provide gamma/X-ray, beta, neutron, and accident neutron dosimetry. NOTE: It was determined in the late 

1960s that the neutron monitoring performed up until that time was not adequate. 

1963 Around March 20, the use of the 0.5 roentgen-to-rem dose conversion factor for body badges exposed to 

low-energy X-rays and plutonium is discontinued (LASL, 1969; 03/20/63 memorandum). 

1972 On January 1, LANL evaluates the assignment of neutron dose equal to TLD-measured gamma dose for 

workers handling Pu-238 (LASL, 1974; 12/03/71 memorandum). NOTE: This appears to have been a 

special study for a relatively small group of workers, possibly using hand-fabricated badges with loose 

chips, because TLDs were in relatively short supply at that time (Widner, 2003). 

7.3.1.6 Application of Co-Worker Data for External Dose Reconstruction 

Co-worker external data can be used to assign doses for workers at DOE sites who have incomplete or 

no individual monitoring data. Such workers may not have individual monitoring data because: (1) 

the worker was unmonitored and, even by today’s standards, did not need to be monitored; (2) the 

worker was unmonitored, but by today’s standards would have been monitored; (3) another worker 

was monitored as representative of a group of similar workers; (4) the worker may have been 

monitored, but the data are not available; or (5) the worker may have partial information but the 

available information is insufficient to facilitate a dose reconstruction. 

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Development of site-specific data summaries and dose distributions requires a careful examination of 

the available data sources to identify the most complete and accurate data set. Prior to this 

examination, a sampling of the site-wide data set is compared to the claim-specific data submitted to 

NIOSH by the DOE site. This comparison can provide information needed to adjust the site-wide 

data set to account for missed dose or for data that may be skewed by an event that would normally 

impact a small number of workers (e.g., a criticality). Should this comparison shed doubt on the 

accuracy or completeness of the data selected for analysis, additional evaluations will take place to 

ensure that a valid data set has been selected. 

Selected co-worker data sets are analyzed to develop annual 50th and 95th percentile doses. Prior to 

these calculations, the doses are adjusted to account for missed dose based on badge exchange 

frequency and dosimeter MDL. For example, the median annual reported dose might be zero at a 

particular site in a particular year, but it would not be appropriate to assign a dose of zero as a median 

value because of the potential for missed dose which must be included in claimants’ dose estimates. 

Specifically, one-half of the maximum annual missed doses are added to the reported annual doses 

with this exception: when there are reported positive doses, the maximum missed dosed is reduced by 

the dose corresponding to one badge exchange (because it is not possible that all individual badge 

results were zero if a positive annual dose was reported). The 50th and 95th percentile annual 

penetrating doses are then derived by ranking the data into cumulative probability curves and 

extracting the 50th and 95th percentile doses for each year. A co-worker external exposure technical 

information bulletin has not been prepared for LANL exposure data at this time. Data summaries of 

exposure records and recommendations on the incorporation of missed photon dose in the site 

co-worker data are provided in the LANL Occupational External Dose TBD, ORAUT-TKBS-0010-6. 

Available records indicate that between 1944 and 1975, an average of 3,100 workers was annually 

monitored for external radiation doses. The number of workers monitored ranged from a low of nine 

workers in 1944 to 4,716 workers in 1975. The limitations in the application of these data as 

co-worker data will, of course, be subject to those same data gaps that resulted from the limitations of 

the available direct-monitoring technology. 

7.3.2 Ambient Environmental External Radiation Doses at LANL 

External ambient photon, and in some cases beta, radiation submersion exposures were possible to 

workers from several sources in a number of TAs. TAs included reactor, criticality, and accelerator 

operations as well as waste disposal areas. One of the primary external environmental exposure 

sources would have been noble gases emitted from the Omega reactor stack in TA-2. Similarly, 

exposures to air activation products from accelerator operation, as well as beam leakage outside of the 

accelerator facilities, were also possible sources of increased levels of gamma radiation. Increased 

gamma radiation was also noted in several Health Division reports on the criticality facilities in 

TA-18. Direct exposure to gamma-emitting contaminants in soils was also possible where spills had 

occurred, or in waste areas (e.g., Acid Canyon) which received direct liquid waste discharges from 

TA-45. Historical reports refer to the placement of area monitoring film badges at various site 

locations. However, the associated data have only been located and available after 1965. 

Contributions to the total external exposure from ambient environmental pathways are primarily a 

concern for unmonitored workers because dose from these pathways would have added to the film 

badge exposure of monitored workers, provided that area monitoring results were not subtracted as 

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background contribution from the employees’ dose records. Based on these conditions, contributions 

and missed dose from environmental external exposure may be accounted for through co-worker data 

evaluations. 

7.3.3 LANL Occupational X-Ray Examinations 

As part of its occupational health and safety program, the site required pre-employment and periodic 

physical medical examinations. These examinations typically included diagnostic chest X-rays. The 

doses from these diagnostic procedures depended on not only the characteristics of the X-ray machine 

and the procedures used, but also examination frequency. The required frequencies were, at a 

minimum, semi-annual through 1963; during the remainder of the evaluation period, examinations 

were performed annually. For all or part of the evaluation period, examinations may have included 

two chest views (posterior-anterior view and/or lateral view). Prior to 1957, site records indicate that 

photofluorography (PFG) equipment was used for exams. Conventional film radiography equipment 

replaced PFG exams after 1957, with the specific equipment and procedures modified over time (e.g., 

beam filters and collimation were added). 

The Occupational Medical Exposure TBD, ORAUT-TKBS-0010-3, combined with complex-wide 

technical information bulletins, International Commission on Radiological Protection (ICRP) 

guidelines, and related agency publications provide methods, recommendations, and default 

claimant-favorable parameters needed to reconstruct the medical exposure portion of a worker’s dose. 

Claim files reviewed include medical records with notations regarding X-ray occurrence. 

7.3.4 External Dose Reconstruction 

Through December 19, 2006, 657 EEOICPA claims from LANL workers with employment dates 

between March 15, 1943 and December 31, 1975 had been submitted to NIOSH. Of those 657 

claims, dose reconstructions have been completed for 300 claims, and three claims are awaiting a 

response to NIOSH’s request for monitoring data. These claims cover the entire range of the LANL 

evaluation period in this report and include claims with external monitoring data. Of these claims, 

zero have external monitoring data between 1943 and 1945, 124 have data between 1946 and 1950, 

and 478 have data between 1951 and 1975. 

There is an established protocol for assessing external exposure when performing dose reconstructions 

(these protocol steps are discussed in the following subsections): 

• Photon Dose 

• Electron Dose 

• Neutron Dose 

• Unmonitored Individuals Working in Production Areas 

• Medical X-ray 

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7.3.4.1 Photon Dose 

The site’s recognition of film dosimeter energy dependence and the impact of varying exposure 

scenarios led to the decision to calibrate and process film badges in-house in order to take these 

conditions into account. Numerous studies are noted in the site Photodosimetry Books in which film 

responses to varying exposure conditions were studied and correction factors developed. 

Furthermore, these issues have been evaluated complex-wide for the dose reconstruction project; the 

results are documented in technical information bulletin ORAUT-OTIB-0010. Film badge over- or 

under-response, and the consequent potential for over- or under-reporting of doses, requires an 

evaluation of a worker’s environment and, when it is claimant-favorable to do so, the application of 

correction factors to the reported dose. In addition, special considerations are required for the TAs 

with low-energy (<30 keV) photons from plutonium where both the deep dose and non-penetrating 

dose are not reliably estimated, and for exposures to mixed gamma and beta fields. The assumptions 

for overestimating dose provided in ORAUT-OTIB-0010 are, therefore, not applicable to LANL’s 

plutonium work areas. The Occupational External Dose TBD, ORAUT-TKBS-0010-6, does provide 

the necessary site-specific evaluation and recommended guidance to account for the lack of dosimeter 

response to low-energy photons. 

1943 through 1945 

During this period, monitoring was primarily performed using PICs. For dose reconstruction cases 

with employment dates that include this timeframe, none of the cases had external dose monitoring 

records before 1946. NIOSH’s review indicates that individual data may not be available, and 

therefore, external dose could not be reconstructed for this period. However, the External 

Occupational Dose TBD does provide summary collective dose data and the number of individuals 

monitored in 1944 and 1945, as well as other years through 2003 (as supplied by LANL). If the 

individual records used in this compilation were available, some reconstructions could be performed, 

although the limited number of monitored workers during 1944 is insufficient to serve as co-worker 

data for the variable exposure conditions of unmonitored workers. ORAUT-OTIB-0010 does not 

allow for application of methodologies for calculating overestimates of external exposure for 

processes or facilities with low-energy photons, and specifically disallows such applications for 

plutonium facilities. These factors and the collective lack of internal monitoring data for several of 

the primary ROCs (as previously described for internal dose reconstruction) preclude the need for 

further evaluation of external doses reconstruction for this time period. 

1946 through 1950 

During this period, the film badge monitoring program was well established; case reviews show that 

approximately one-half include external monitoring data records. The dosimetry transitioned from 

unfiltered film badges to lead cross badges, brass-enclosed film badges, brass clip badges, and finally 

to the brass-lead film badge during 1950. The various badge types in use during this time also were 

subject to the energy dependence previously discussed. The addition of the brass clip reduced the 

required assumptions for determining the beta and gamma components of the film response, and the 

addition of the lead filter supported differentiation of the gamma energy response. NIOSH contends 

that adequate records of monitored external photon radiation doses are available for dose 

reconstruction for this period. Additionally, there is adequate process-specific information and 

documentation regarding the estimated relative percentages of the photon energy bins (<30, 

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30-to-250, and >250 keV) applicable to specific processes, TAs, or buildings. Correction factors have 

been developed that may be applied when warranted and it is claimant-favorable to do so. In addition, 

the minimum detection capability of the film dosimetry has been evaluated and, together with known 

exchange frequencies, allows missed doses to be factored in for reconstruction. However, the lack of 

internal monitoring data for MFPs and other radionuclides (as previously described for internal dose 

reconstruction) precludes the need for further evaluation of external dose reconstruction for this time 

period. 

1951 through 1970 

In 1951, a brass-cadmium film badge replaced the brass-lead film badge and was used until 1962. 

The multi-element Cycolac badge was used from 1962 through the remainder of the evaluation period 

(1975). In addition to the various filters for reducing photon energy dependence, both of these badge 

types included an open window for beta and low-energy gamma evaluation, neutron dosimetry 

capabilities, and activation foils for criticality accident dosimetry. Although the photon energy 

dependence response was reduced with the Cycolac badge, continuing site evaluations of response to 

exposure conditions determined that the brass-cadmium badge underestimated the dose in the 

low-energy plutonium photon environment by a factor of two to three, depending on whether the 

photons were filtered by glovebox glass or steel. The Cycolac badge in similar configurations was 

found to correctly estimate the dose from the higher-energy component, but overestimated the dose 

from the lower-energy component in the presence of glass or steel filtration. NIOSH contends that 

adequate records of monitored external photon radiation doses are available for dose reconstruction 

during this period. In addition, there is adequate process-specific information and documentation 

regarding the estimated relative percentages of the photon energy bins (<30, 30-to-250, and >250 

keV) applicable to most specific processes, TAs, or buildings. Correction factors have been 

developed that may be applied when warranted and it is claimant-favorable to do so. One exception is 

the uranium-handling areas, for which exposures prior to 1957 were assigned as pure beta exposures. 

These results were retrospectively converted to include gamma exposure by including a factor of 1/10 

the total exposure measured. In addition, the minimum detection capability of the film dosimetry has 

been evaluated and, together with known exchange frequencies, may allow missed doses to be 

factored into the reconstruction. However, the lack of internal monitoring data for MFPs and other 

radionuclides (as previously described for internal dose reconstruction) precludes the need for further 

evaluation of external dose reconstruction for this time period. 

1971 though 1975 

During this time period, the multi-element Cycolac badge was in use and provided a more accurate 

estimation of external doses for the intermediate to higher-energy photon bins, with the previouslydiscussed over-response to filtered, low-energy photons. These dosimetry records are available and 

permit reconstruction of individual dose and are sufficient to develop co-worker data for assigning 

dose for unmonitored workers. Because of the minimization of the energy dependence, the need to 

apply correction factors to the recorded dose is also minimized. Recommended adjustments (if 

needed and claimant-favorable) as well as photon energy distributions for assigning deep dose by 

process are provided in the Occupational External Dose TBD, ORAUT-TKBS-0010-6. Missed dose 

may be accounted for via review of exchange frequencies and corresponding minimum detection 

limits. 

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7.3.4.2 Electron Dose 

1943 through 1948 

During this time period, beta (electron) shallow doses were not specifically monitored, although beta 

radiation was the dominant external radiation hazard during uranium handling. Historical 

documentation indicates numerous instances of beta overexposures from uranium, fission products, 

and other unspecified sources. Shallow-dose-to-deep-dose ratios have been evaluated for LANL 

workers over a ten-year period from the onset of shallow dose monitoring in 1949 until 1958. The 

evaluation calculated a median annual shallow and deep dose and recommended that a dose of 1.008 

times the reported deep dose be attributed to beta radiation for dose reconstruction. Provided that the 

exposure scenarios and source terms for the period from which the ratio was developed are similar to 

the unmonitored period currently under evaluation, beta external dose reconstruction would be 

possible for a portion of the 1943-48 period (i.e., 1946 and after), or for individuals with external 

photon monitoring records. However, the lack of internal monitoring data for MFPs and other 

radionuclides (as previously described for internal dose reconstruction) precludes the need for further 

evaluation of shallow external dose reconstruction for this time period. 

1949 through 1975 

Throughout this period, beta radiation fields continued to be a source of exposure from most 

operations. Exposure records are available and include the skin dose from which the non-penetrating 

dose may be estimated and attributed as the beta category after subtracting any reported deep, neutron 

and tritium doses. Missed dose may be applied based on the MDL for the time period and the 

exchange frequency. However, the lack of internal monitoring data for MFPs and other radionuclides 

(as previously described for internal dose reconstruction) precludes the need for further evaluation of 

shallow external dose reconstruction for most of this time period. 

7.3.4.3 Neutron Dose 

Throughout the period under evaluation, neutrons were a significant source of external dose in 

plutonium, metallurgy, and research TAs, and in those TAs with operating reactors, accelerators, and 

criticality experiments. In some areas, it is possible that up to 90% of the total dose was attributable 

to the neutron component. There was no neutron monitoring dosimetry until 1949 when NTPs were 

issued for monitoring fast neutrons. Thermal neutron monitoring began in 1953 by comparing the 

optical densities beneath the cadmium and brass filters in the brass-cadmium film badges; monitoring 

ceased in 1955 and resumed in 1956. While studying the implementation of thermoluminescent 

dosimeters, the AEC (predecessor to DOE) determined that neutron doses had been underestimated as 

a result of the NTA response threshold of 700 keV. A review of the neutron fluence energy spectrums 

for various plutonium areas provided in the TBD show that most of the neutron energies are below 

this threshold (ORAUT-TKBS-0010-6). Together, the lack of monitoring and the identified underresponse of the neutron dosimetry impede the reconstruction process, increase the missed dose that 

must be accounted for, and increase the overall uncertainty of the calculated dose. 

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The reconstruction of neutron dose would require assigning all neutron doses as missed doses for the 

period. Technical Information Bulletin ORAUT-OTIB-0023 provides guidance on applying missed 

neutron dose for monitored workers. However, the recommended method cannot be applied for 

LANL because the TIB excludes use of the recommended guidance in cases where the doses were not 

reliably measured, or if the neutron dose would have exceeded 75% of the photon dose; the TBD 

(ORAUT-TKBS-0010-6) provides a range of neutron-to-photon dose from 0.30 to 5.5. In the absence 

of reliable monitoring data, neutron dose reconstruction for monitored workers requires application of 

neutron-to-photon ratios. The ratio method is based on the assumption that, in most cases, neutrons 

would be present with an associated gamma radiation field. The required information to apply this 

approach for the various neutron sources includes estimations of the gamma-to-neutron ratio, the 

percentage of neutrons in each of the energy bins by area/process, the exposure geometry and 

distance, and the neutron dose fraction for each energy bin. The TBD provides the recommended 

factors. Site-specific issues that may hinder the recommended approach are situations where specific 

work groups were not issued film badge dosimetry; for example, when the issuance of film badges to 

workers preparing Po-Be initiators was discontinued after a three-month study showed no gamma 

exposure and the primary dose concern to be neutrons. Such situations require evaluation on a caseby-case basis. The lack of internal monitoring data for MFPs and other radionuclides (as previously 

described for internal dose reconstruction) precludes the need for further evaluation of neutron dose 

reconstruction for most of this time period. From 1971 to 1975, the data used in the development of 

ratios and other process/area-specific variables for applying neutron-to-photon dose ratios are 

considered appropriate for reconstructing doses for that specific timeframe because the data used to 

develop the relationships presented in the TBD were generated near this time period and should 

represent the contemporary exposure conditions. 

7.3.4.4 Unmonitored Individuals Working in Production Areas 

There is possibly a large population of production area workers who were not monitored, especially 

before 1946, because the site never adopted a monitoring program that included all workers. 

Documentation of these and other concerns arising from the review of site records is provided in 

Section 7.4.3. There are co-worker data available that can be analyzed and applied for assigning dose 

to unmonitored production-area workers, especially for 1946 and beyond. Assurance of assigning 

claimant-favorable doses to such workers must account for the combined effects of instances of 

inconsistent monitoring (as described in Section 7.4.3), inadequacy of the neutron dosimetry program, 

lack of beta radiation monitoring prior to 1949, and adjustment to photon radiation doses. 

7.3.4.5 Medical X-ray 

Medical X-rays were initially performed semi-annually; later they were done annually. The year 

X-rays were taken will impact the assigned medical X-ray dose. Prior to 1957, the use of PFG 

equipment would result in assigning higher doses compared to the conventional film radiography 

equipment used after 1957. It would be claimant-favorable to assume two chest x-rays for each 

examination, one AP and one LAT. 

The Occupational Medical Dose TBD, ORAUT-TKBS-0010-3, combined with complex-wide 

technical information bulletins and ICRP and related agency publications provide methods, 

recommendations, and default claimant-favorable parameters needed to reconstruct the medical 

exposure portion of a worker’s dose. 

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7.3.5 External Dose Reconstruction Feasibility Conclusion 

This evaluation has established that NIOSH does not have sufficient information to either: (1) 

estimate the maximum external radiation dose for every type of cancer for which radiation doses are 

reconstructed that could have been incurred under plausible circumstances by any member of the 

class; or (2) estimate the external radiation doses to members of the class more precisely than a 

maximum dose estimate for the period 1943 through 1949. However, it is possible that some external 

doses for some members of the proposed class could be reconstructed for this early time period. With 

appropriate claimant-favorable assumptions addressing missed doses, maximizing external radiation 

dose estimations for the 1950 to 1975 timeframe can be performed provided that appropriate, 

claimant-favorable missed neutron doses are applied. 

7.4 Evaluation of Petition Basis for SEC-00051 

The following subsections evaluate the assertions made on behalf of petition SEC-00051 for the Los 

Alamos National Laboratory. 

7.4.1 Evaluation of Major Topics Detailed in Petition SEC-00051 

The following major topics were detailed in petition SEC-00051. Italicized statements are from the 

petition; the comments that follow are from NIOSH. 

7.4.1.1 Insufficient Data 

SEC-00051: The National Institute of Occupational Safety and Health (NIOSH) is not able to estimate 

with sufficient accuracy radiation doses for members of the identified class. 

Accurate data required for NIOSH to conduct precise dose reconstructions of members of the 

specified class does not exist for some employees (It has been determined that there is insufficient 

information to estimate the maximum radiation dose incurred by any member of the class being 

evaluated.) 

With respect to these employees it has been determined that there is insufficient information to 

estimate either the maximum radiation dose incurred by any member of the class being evaluated. 

The information available from the site profile and additional resources is insufficient to document or 

estimate the maximum internal and external potential exposure to members of the class during the 

period of radiological operations at LANL. 

NIOSH has stated that such data does not exist for the early years of the Los Alamos National 

Laboratory. The site profile clearly states that no definitive historical information exists. As cited, in 

reports as current as the ORAU Team Dose Reconstruction Project Report for NIOSH, dated August 

16, 2005, no environmental exposure data exists prior to 1965. Also, there are references made in the 

U.S. Department of Energy Environment, Safety, and Health, Tiger Team Assessment, November 

1991, to the lack of documentation and administrative requirements for evaluating personnel 

exposures from unusual internal exposures to radioactive materials. 

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Workers with potential exposures to fission or activation products prior to 1955 (possibly 1958) were 

not monitored. 

The primary data used for determining internal exposures are personal monitoring data, such as 

urinalyses, fecal samples, and whole-body counting results. If such data are unavailable, then air 

monitoring data from breathing zone and general area monitoring are used to estimate potential 

internal exposure. If both personal monitoring and breathing zone area monitoring are unavailable, 

internal exposures can sometimes be estimated using more general area monitoring, process 

information, and information characterizing and quantifying the source term. The LANL in vitro and 

in vivo databases have been found to contain only data specific to internal exposure to tritium, 

polonium, plutonium, and uranium. There are no fission product internal monitoring data available 

from September 1, 1944 through July 18, 1963, as established in the evaluation report for petition 

SEC-00061. Additional independent reviews have resulted in an extension of the time period 

designated as lacking internal monitoring for fission products and other primary ROCs through 

December 31, 1975. In addition, the determination has been made that there are insufficient air 

monitoring data available with which intake modeling could be performed for the period March 15, 

1943 through December 31, 1971. 

The same data hierarchy is used for determining external exposures to the cancer site. Personal 

monitoring data from film badges or thermoluminescent dosimeters (TLDs) are the primary data used. 

If there are no personal monitoring data, exposure rate surveys, process, and source-term modeling 

can sometimes be used to reconstruct the potential exposure. The external radiation hazards 

associated with LANL were recognized from the beginning of operations. Dosimetry badges were 

provided to workers who had significant exposure potential and the monitoring records from this 

program are available to NIOSH. 

NIOSH has compiled and published a more complete summary of the available LANL external 

monitoring information, including detailed descriptions of the dosimeters used and the radiological 

operations at LANL. This information is summarized in the LANL TBD (ORAUT-TKBS-0010) and 

is available online at: http://www.cdc.gov/niosh/ocas. 

A more detailed discussion of the information required for dose reconstruction can be found in 

OCAS-IG-001, Internal Dose Reconstruction Implementation Guide, and OCAS-IG-002, External 

Dose Reconstruction Implementation Guide. These documents are available at: 

http://www.cdc.gov/niosh/ocas/ocasdose.html. 

The goal of NIOSH dose reconstructions is, at a minimum, to overestimate the maximum possible 

dose an energy employee could have reasonably received during his or her work at the facility. Where 

records do not exist for whatever reason, this overestimation causes the dose reconstruction to be 

“claimant favorable.” Guidance for reconstructing doses using the overestimating methodology is 

provided in programmatic technical information bulletins. However, it has been determined that 

certain site-specific conditions specifically exclude application of these methods for LANL workers 

for the period 1943 through 1971. 

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7.4.1.2 Records Do Not Exist 

SEC-00051: In many cases from 1943-1975 personal exposures in some job categories with 

significant radiation exposures were unrecorded. 

There are many incidents and accidents documenting the history of occurrences at the LANL which 

are not included or made available in the dose reconstruction process. 

The potential for unmonitored intakes was significant in the early years (1944-1946) for any site 

worker. 

Valid radiological readings for individuals do not exist for this class. 

NIOSH’s approach to dose reconstruction has always been to provide the claimant with an estimate of 

dose that will allow the Department of Labor to arrive at the correct compensation decision (i.e., the 

probability of causation is on the correct side of 50%). To accomplish this, individual monitoring data 

have been given the highest emphasis. NIOSH has worked with LANL and obtained extensive 

monitoring record data sets for the period March 15, 1943 through December 31, 1975. These data 

sets include individual worker external dosimetry reports and internal bioassay results for the major 

radionuclides (plutonium, uranium, polonium, and tritium). Summary results show that 80.5% of 

cases have external data for at least a portion of their work history, and 58.9% have some internal 

bioassay data. When reconstructing doses for even infrequently-monitored workers, the dose 

reconstruction will often rely on missed dose. The calculation of missed dose attempts to answer the 

question: Given the individual monitoring data, what is the maximum plausible dose that could have 

been received by the worker without being detected by the monitoring program? This approach, 

coupled with the assumption of chronic exposure conditions (where applicable) is inclusive of any 

exposure that might have been received as a result of an incident. For unmonitored workers, who 

were in exposure conditions in which they should have been monitored, NIOSH applies a co-worker 

model that assumes that these workers were exposed to the upper end of the distribution of results 

collected from the monitored population. 

The purpose of the LANL site profile (ORAUT-TKBS-0010) is not to report every incident or 

accident (collectively referred to as occurrences) that ever transpired at LANL, but rather to serve as a 

guide to dose reconstructors for uniformly assessing LANL claims. While it is known that some 

reported occurrences resulted in worker radiation exposures, it is also known that an equal or larger 

number of occurrences resulted in minimal or no exposures at all. 

The site profile provides useful data to the dose reconstructors for completing claimant dose 

assessments. To this end, the site profile provides a summary of major events highlighting potentially 

significant releases or exposure events. Upper-bound values for the types and magnitudes of incidents 

that occurred can allow dose reconstructors to develop conservative estimated intakes for both 

monitored and unmonitored workers. Work continues on characterizing and quantifying the intakes 

for both maximizing and general conditions. Other approaches being used to account for missed dose 

or to assign dose to unmonitored workers include the use of co-worker data and other workplace 

survey data (when available). 

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7.4.1.3 Lack of Bioassay Data 

SEC-00051: Travel throughout areas of LANL to perform work assignments was often necessary for 

some classes... Even though this individual traveled to these areas, he or she was not required to 

participate in the bioassay program. 

The lack of bioassay data raises the issue of possible chronic exposure to external sources of 

radiation. 

There is a lack of internal dose (bioassay data) data and occupational environment dose (air sample 

test results) data for the stated class of employees. 

No environmental exposure data exists prior to 1965. 

Bioassay programs were not set up for all employees. 

The primary data used for determining internal exposures are personal monitoring data, such as 

urinalyses, fecal samples, and whole-body counting results. If these are unavailable, air monitoring 

data from breathing zone and general area monitoring are used. If both personal monitoring and 

breathing zone area monitoring are unavailable, internal exposures can sometimes be estimated using 

more general area monitoring, process information, and information characterizing and quantifying 

the source term. 

As stated previously, bioassay results for specific radionuclides or categories of radionuclides are not 

available for all time periods covered by the petition. This evaluation has established that neither in 

vivo nor in vitro data are available for mixed fission products prior to the consistent use of the 

whole-body counter in 1970, and that these data are insufficient for developing co-worker scenarios 

after this time. In lieu of bioassay data, air monitoring data may be applied to assign worker intakes 

and associated internal doses. However, it has also been established that currently available 

radionuclide-specific air monitoring data are insufficient prior to 1971; records after 1971 may not be 

representative of potential exposure conditions earlier in the site’s history. Further validation, 

analysis, and review of the newly-identified records would be required to alter this conclusion. 

Furthermore, there is sufficient documentation of numerous other unsealed (and in some cases more 

exotic) radionuclides being used. These other radionuclides were present in much lower quantities 

than the primary ROCs and their use generally affected more limited areas. These radionuclides are 

presented in Section 7.2 and included Th-232, Cm-244, Ac-227, Cf-252, Np-237, Am-241, and 

U-233. Internal bioassay data or in vivo data have not been identified for most of these radionuclides 

through 1975. Some data may be available for the later years. 

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7.4.3 Evaluation of General Concerns Raised in Petition SEC-00051 

The following excerpts from LANL historical documentation corroborate the general concerns raised 

in petition SEC-00051 for a substantial portion of the timeframe under evaluation. These general 

concerns include the absence of bioassay data, undocumented overexposures, and inadequate 

monitoring procedures. 

History of the Health Group (A-6) (March 1942 – November 1945) (Hempelmann, 1945): 

•	 The following is a compilation of the criticism which can be directed against the health group with 

justification: 1) Failure to inspect regularly all technical operations on this project for health 

hazards...Occasionally the Health Group did not learn of potentially dangerous experiments until 

they were completed. 2) Incomplete record of dosage received by all persons exposed to external 

radiation and lack of negative exposure records (for legal purposes) of persons not working with 

radiation. 

•	 Since the Health Group could not be policemen and monitor every technical operation, the only 

means to obtain records of exposure of personnel to radiation was to depend on the cooperation 

of persons involved. All people did not cooperate to the fullest extent; hence, records of exposure 

are incomplete in the cases of some individuals. Exposure records were complete until the fall of 

1944 and then less so. 

Annual Report, Health Division, 1951 (LASL HD, 1951): 

•	 Two problems which need further work are the fission product air contamination around the 

Omega Water Boiler and the beta exposure rate while working Water Boiler Soup. 

NIOSH Note: There are no fission product internal monitoring data available for this time period. 

•	 Casting, machining, and other operations on thorium metal were undertaken by several 

Laboratory Groups this year. 

NIOSH Note: There are no bioassay data available for thorium. 

•	 Method for determining curium in urine, while still having certain deficiencies, was being used to 

some extent. 

NIOSH Note: There are no bioassay data available for curium. 

•	 At DP East, an experimental program with actinium has been carried out by CMR-3. As far as we 

have been able to determine, the personnel have not been subject to overexposure. The health 

program on this work has not been too satisfactory. An adequate urine analysis is not available 

and it is difficult to evaluate air samples. 

NISOH Note: There were only 15 bioassay results available for actinium. 

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Annual Report, Health Division, 1949 (LASL HD, 1949): 

•	 Starting about the first of the year, the personnel film badges were changed to provide an 

unshielded area of film that will respond to beta or soft-gamma radiation. The main result of this 

change was the discovery of many cases of high exposure, and fair number of overexposures to 

beta radiation from normal uranium. 

•	 Past experience has shown that many maintenance and construction jobs have been started 

without adequate health clearance. Failures have occurred mainly because of lack of knowledge 

of the existence of health hazards in various locations... 

•	 ...many cases of contamination, overexposure, misuse of radiation sources, etc. have been 

discovered more or less by accident. 

Photodosimetry Evaluation Book, Volume II, 1960-1969 (LASL PEB, 1969): 

•	 ...the monitoring section leader estimates that 25 percent of the 1,500 University employees now 

issued film badges do not wear them at all times when working with radiation... 

NIOSH Note: The word “now” in the above text means 1960. 

•	 Although film badges are required in order to gain access to certain sites, at present there is no 

way of determining if they are worn inside the site. It is interesting to note that three people have 

been killed by radiation at Los Alamos and that none of them were wearing film badges. 

Photodosimetry Evaluation Book, Volume 1a (LASL PEB, 1959): 

•	 Investigations of Sigma and illegible personnel film result outliers were investigated and 

determined that the personnel left the badges on benches with material, wore improperly on wrist, 

or left the badge in another building. Other notations of personnel badges being stored in dirty 

smocks, drawers, and work areas. Notation regarding not reading the film badges of DP East 

polonium workers as alpha and neutron radiation the primary concern, the wearing of film was 

not applicable and to monitor by finger impressions. Notation for DP West plutonium workers to 

only issue catastrophe badges. 

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7.5 Other Issues Relevant to the Petition Identified During the Evaluation 

During the feasibility evaluation for SEC-00051, a number of issues were identified that needed 

further analysis and resolution. The issues and their current status are: 

•	 ISSUE: What type of bioassay data is LANL providing to NIOSH/ORAU? Does it include data 

from all radionuclides handled at LANL? 

APPROACH: As discussed in Section 7.2, in vitro bioassay data are available for part of the 

evaluation period for uranium, plutonium, tritium, polonium, and to a lesser extent, americium. In 

vivo measurements began in the late 1960s for gamma-emitting fission and activation products and 

plutonium and americium. In later years, uranium was also added to the standard in vivo analytes. 

There was some screening done in the 1950s through 1970, but the in vivo program was not 

well-established at that time and there are no data available. The capabilities and available data 

for assessing intakes of all ROCs applicable to in vivo monitoring were determined to be 

incomplete through 1975. NIOSH is continuing to review the feasibility of LANL dose 

reconstruction for the post-1975 time frame. 

Some bioassay results may be available for other radionuclides handled in limited amounts, such 

as Sr-90 and Ac-227. However, these data have not been provided by LANL to date. 

•	 ISSUE: How can dose reconstruction be accomplished for fission products and other radioisotopes 

where the TBD, page 30, notes that many are not accounted for in the site’s exposure analysis of 

generated fission product sources? 

APPROACH: At this time, internal dose reconstructions cannot be performed for MFP during the 

period 1943 through 1969. The capabilities and available data for assessing intakes of all ROCs 

conducive to in vivo monitoring require further evaluation from 1970 on, and also evaluation of 

the newly-identified records for the years prior to 1970. 

•	 ISSUE: The TBD recognizes that effluents from many TAs have not been well-reported over the 

last several decades and that LANL has not provided effluent data for the years 1945-1971. Since 

it does not exist, what assurance is there that use of rather sparse environmental measurements, 

and very few source terms, will enable adequate overall environmental dose estimates? 

APPROACH: Recently-released LANL documents associated with the Los Alamos Historical 

Document and Assessment project are being reviewed to determine whether additional 

information is available to fill sampling and effluent data gaps. Another source of on-going work 

involves development of co-worker data that could possibly be used, in some instances, to account 

for doses from releases. 

•	 ISSUE: How will claimant-favorable neutron doses for workers be accounted for when most of 

the entire neutron spectrum is below the practical 1-MeV detection limits of NTA film used in the 

workers’ badges or for the periods in time when there was no neutron monitoring? 

APPROACH: Section 7.3.4.3 discusses limitations of the neutron dosimetry and recommendations 

for application of photon-to-neutron ratios in deriving neutron dose. 

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7.6 Summary of Feasibility Findings for Petition SEC-00051 

This report evaluated the feasibility for completing dose reconstructions for LANL employees in all 

TAs from March 15, 1943 through December 31, 1975. NIOSH found that the monitoring records, 

process descriptions, and source-term data available are not sufficient to complete dose 

reconstructions for the proposed class of employees, at a minimum, through December 31, 1975. 

Table 7-10 summarizes the results of the feasibility findings at LANL for each exposure source for the 

time period March 15, 1943 through December 31, 1975. 

Table 7-10: Summary of Feasibility Findings for SEC-00051 

March 15, 1943 through December 31, 1975 

Source of Exposure Reconstruction Feasible Reconstruction Not Feasible 

Internal1 

H-3 

Po 

Pu 

U 

 Ac, Cm, Np, Th, Sr

 Various isotopes of concern

 MFP/MAP 

1950 – 1975 

1944 – 1956 

1944 – 1975 

1943 – 1975 

1943 – 1949 

1943 – 1975 

1943 – 1975 

1943 – 1975 

External2

 Gamma 1946 – 1975 1943 – 1945 

Beta 1949 – 1975 1943 – 1948

 Neutron 1946 – 1975 1943 – 1945 

Occupational Medical X-ray 1943 – 1975 --- 

1	 Limited environmental air monitoring data and whole-body/chest count data are available beginning in 1970. 

2	 Gamma, beta, and neutron dose reconstruction is feasible for 1943-1969 provided that NIOSH has the individual 

monitoring/source term/area monitoring/co-worker data. 

As of December 19, 2006, a total of 657 claims have been submitted to NIOSH for individuals who 

worked at LANL. Dose reconstructions are complete for 300 individuals (~46%). 

Reiterating the discussion in Section 4.4, the review of completed and pending cases included a wide 

variety of job titles, including: carpenter, electrician, machinist, chemist, security guard, technician, 

physicist, custodian, animal caretaker, vehicle inspector, and research scientist. Years of service 

ranged from less than one year up to 42 years. Completed reconstructions used various approaches, 

both underestimates (partial reconstructions) and overestimates. Reconstructions that have been 

completed for monitored worker cases applied available external and internal monitoring data as well 

as missed dose. For cases with monitoring gaps, or where the worker did not have either internal or 

external monitoring data, the reconstructions relied on co-located worker data (e.g., when the worker 

was involved in an incident), technical information bulletins ORAUT-OTIB-0002 and ORAUT110 of 117 
 

SEC-00051 02-01-07 LANL
 

OTIB-0018, ambient on-site doses from other DOE sites, internal co-worker data from across the 

DOE complex, radiological protection guide values, or TBD-tabulated values. 

The dose reconstructions completed to date do not demonstrate that NIOSH can estimate with 

sufficient accuracy the maximum radiation dose for every type of cancer for which radiation doses are 

reconstructed that could have been incurred under plausible circumstances by any member of the 

class, or that sufficient information is available to estimate the radiation doses of members of the class 

more precisely than an estimate of the maximum radiation dose. Of the 66 cases that were reviewed 

for this evaluation, 27 cases had been completed, 15 of which were partial reconstructions using 

available monitoring data. The remaining 12 cases were overestimates for workers whose job 

descriptions did not indicate significant, if any, involvement with radioactive materials, or whose 

individual claim information (including employment information, exposure information/potential, and 

incurred cancer) sufficiently supports the performance of an overestimating dose reconstruction in the 

evaluation of the probability of causation. 

8.0 Evaluation of Health Endangerment for Petition SEC-00051 

The health endangerment determination for the class of employees covered by this evaluation report is 

governed by both EEOICPA and 42 C.F.R. § 83.13(c)(3). Under these requirements, if it is not 

feasible to estimate with sufficient accuracy radiation doses for members of the class, NIOSH must 

also determine that there is a reasonable likelihood that such radiation doses may have endangered the 

health of members of the class. Section 83.13 requires NIOSH to assume that any duration of 

unprotected exposure may have endangered the health of members of a class when it has been 

established that it is not feasible to reconstruct (the incident) exposures for the class and that the class 

may have been exposed to radiation during a discrete incident likely to have involved levels of 

exposure similarly high to those occurring during nuclear criticality incidents. If the feasibility 

determination of the inability to reconstruct doses from an exceptionally high-level exposure has not 

been established, but NIOSH has determined that it is not feasible to reconstruct other (long-term) 

exposures, then NIOSH is required to specify that health was endangered for those workers who were 

employed for a number of work days aggregating at least 250 work days within the parameters 

established for the class or in combination with work days within the parameters established for one 

or more other classes of employees in the SEC. 

This evaluation determined that it is not feasible to estimate the long-term radiation dose for members 

of the proposed class with sufficient accuracy based on the sum of information available from 

available resources. A modification to the class definition regarding health endangerment and 

minimum required employment periods, therefore, is required. 

NIOSH has determined that some members of the class may have been exposed to radiation during 

documented discrete criticality incidents (as previously discussed) that were likely to have involved 

high levels of exposure. 

The evidence reviewed in this evaluation indicates that some workers in the class may have 

accumulated chronic (long-term) radiation exposures through intakes of radionuclides and from direct 

exposure to radioactive materials. Relevant data are not available from which an estimate of all 

radionuclide source terms can be developed; nor are adequate and complete area, environmental, in 

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vivo, or in vitro monitoring data. Therefore, NIOSH is unable to estimate maximum doses associated 

with internal exposures and, in some cases, external exposures. Consequently, NIOSH is specifying 

that health was endangered for those workers covered by this evaluation who were employed for a 

number of work days aggregating at least 250 work days within parameters established for this class, 

or in combination with work days within the parameters established for one or more other classes of 

employees in the SEC, or were otherwise involved in an incident. 

9.0 NIOSH-Proposed Class for Petition SEC-00051 

Based on its research, NIOSH reduced the petitioner-requested class to define a single class of 

employees for which NIOSH cannot estimate radiation doses with sufficient accuracy. The 

NIOSH-proposed class includes all job titles and/or job duties for all employees of the DOE or DOE 

contractors or subcontractors who were monitored, or should have been monitored, for radiological 

exposures while working in operational Technical Areas with a history of radioactive material use at 

the Los Alamos National Laboratory for an aggregate of at least 250 work days during the period from 

March 15, 1943 through December 31, 1975, or in combination with work days within the parameters 

established for one or more other classes of employees in the SEC. This definition excludes TA-1-Z, 

TA-17, -19, -28, -34, -38, -57, -64, -65, -69, -70, and -74. The class was modified in order to: (1) 

specify the date when project staff began work at the site (March 15, 1943); (2) confine the class to 

those TAs that had a history of radioactive material use and were also operational during the 

evaluation period; and (3) explicitly include all personnel who worked for the DOE, DOE contractors, 

or subcontractors (including all former MED/AEC workers) who were monitored or should have been 

monitored for radiological exposure. NIOSH will continue its evaluation to determine at what 

historical point (after the evaluation period addressed herein) that available information and data 

become adequate to: (1) estimate the maximum radiation dose incurred by any site worker; or (2) 

estimate radiation doses more precisely than a maximum dose. 

NIOSH has carefully reviewed all material sent in by the petitioner, including the specific assertions 

stated in the petition, and has responded herein (see Section 7.4). NIOSH has also reviewed available 

technical resources and many other references, including the Site Research Data Base (SRDB), for 

information relevant to SEC-00051. In addition, NIOSH reviewed its NOCTS dose reconstruction 

database to identify EEOICPA-related dose reconstructions that might provide information relevant to 

the petition evaluation. 

These actions are based on existing, approved NIOSH processes used in dose reconstruction for 

claims under EEOICPA. NIOSH’s guiding principle in conducting these dose reconstructions is to 

ensure that the assumptions used are fair, consistent, and well-grounded in the best available science. 

Simultaneously, uncertainties in the science and data must be handled to the advantage, rather than to 

the detriment, of the petitioners. When adequate personal dose monitoring information is not 

available, or is very limited, NIOSH may use the highest reasonably possible radiation dose, based on 

reliable science, documented experience, and relevant data to determine the feasibility of 

reconstructing the dose of an SEC petition class. NIOSH contends that it has complied with these 

standards of performance in determining that it would not be feasible to reconstruct the dose for the 

class proposed in this petition. 

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10.0 References 

42 C.F.R. 81, Guidelines for Determining the Probability of Causation Under the Energy Employees 

Occupational Illness Compensation Program Act of 2000; Final Rule, Federal Register/Vol. 67, No. 

85/Thursday, p 22,296; May 2, 2002; SRDB Ref ID: 19391 

42 C.F.R. 82, Methods for Radiation Dose Reconstruction Under the Energy Employees Occupational 

Illness Compensation Program Act of 2000; Final Rule; May 2, 2002; SRDB Ref ID: 19392 

42 C.F.R. 83, Procedures for Designating Classes of Employees as Members of the Special Exposure 

Cohort Under the Energy Employees Occupational Illness Compensation Program Act of 2000; Final 

Rule; May 28, 2004; SRDB Ref ID: 22001 

42 U.S.C. §§ 7384-7385 [EEOICPA], Energy Employees Occupational Illness Compensation 

Program Act of 2000, as amended 

DOE/EH-0027, Department of Energy Standard for the Performance Testing of Personnel Dosimetry 

Systems, U.S. Department of Energy; 1986; SRDB Ref ID: 12294 

DOE/EIS-0238, Sitewide Environmental Impact Statement for the Continued Operation of the Los 

Alamos National Laboratory, U.S. Department of Energy; 1999; SRDB RefID: 13468 

DOE-STD-1128-98, Guide of Good Practices for Occupational Radiological Protection in Plutonium 

Facilities, Section 6.2.3., Change Notice 3; Department of Energy Standard; February, 2005; SRDB 

Ref ID: 22723 

OCAS-IG-001, External Dose Reconstruction Implementation Guide, NIOSH, Office of 

Compensation Analysis and Support (OCAS); Rev. 1; August, 2002; SRDB Ref ID: 22401 

OCAS-IG-002, Internal Dose Reconstruction Implementation Guidelines, Rev. 0; Office of 

Compensation Analysis and Support; August 2002; SRDB Ref ID: 22402 

OCAS-PR-004, Internal Procedures for the Evaluation of Special Exposure Cohort Petitions, 

NIOSH, Office of Compensation Analysis and Support (OCAS); Cincinnati, Ohio; September 23, 

2004; SRDB Ref ID: Not currently available in the SRDB 

ORAUT-OTIB-0002, Maximum Internal Dose Estimates for Certain DOE Complex Claims, Rev. 01 

PC-2; May 7, 2004; SRDB Ref ID: 19409 

ORAUT-OTIB-0010, A Standard Complex-Wide Methodology for Overestimating External Doses 

Measured with Film Badge Dosimeters, Rev. 01; June 5, 2006; SRDB Ref ID: 19429 

ORAUT-OTIB-0018, Internal Dose Overestimates for Facilities With Air Sampling Programs, Rev. 

01; August 9, 2005; SRDB Ref ID: 19436 

ORAUT-OTIB-0019, Analysis of Coworker Bioassay Data for Internal Dose Assignment, Rev. 01; 

October 7, 2005; SRDB Ref ID: 19438 

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ORAUT-OTIB-0023, Assignment of Missed Neutron Doses Based on Dosimeter Records, Rev. 00; 

March 7, 2005; SRDB Ref ID: 19444 

ORAUT-OTIB-0053, draft, Dose Reconstruction Considerations for Recycled Uranium 

Contaminants; Oak Ridge Associated Universities; Oak Ridge, Tennessee; SRDB Ref ID: Not 

currently available in the SRDB 

ORAUT-OTIB-0062, draft, Internal Dosimetry Coworker Data for Los Alamos National Laboratory, 

Oak Ridge Associated Universities; Oak Ridge, Tennessee; SRDB Ref ID: Not currently available in 

the SRDB 

ORAUT-OTIB-0063, draft, Los Alamos National Laboratory Bioassay Data Project Final Report; 

Oak Ridge Associated Universities; Oak Ridge, Tennessee; SRDB Ref ID: Not currently available in 

the SRDB 

ORAUT-PROC-0095, Generating Summary Statistics for Coworker Bioassay Data; Rev. 00; June 5, 

2006; Oak Ridge Associated Universities; Oak Ridge, Tennessee; available on ORAUT Intranet 

ORAUT-TKBS-0010-1, Technical Basis Document for Los Alamos National Laboratory – 

Introduction, Rev. 00; January 25, 2005; SRDB Ref ID: 19560 

ORAUT-TKBS-0010-2, Technical Basis Document for Los Alamos National Laboratory – Site 

Description, Rev. 00; May 7, 2004; SRDB Ref ID: 19561 

ORAUT-TKBS-0010-3, Technical Basis Document for Los Alamos National Laboratory – 

Occupational Medical Dose, Rev. 00; December 29, 2004; SRDB Ref ID: 19562 

ORAUT-TKBS-0010-4, Technical Basis Document for Los Alamos National Laboratory – 

Occupational Environmental Dose, Rev. 00; October 8, 2004; SRDB Ref ID: 19564 

ORAUT-TKBS-0010-5, Technical Basis Document for Los Alamos National Laboratory – 

Occupational Internal Dose, Rev. 00; December 21, 2004; SRDB Ref ID: 19565 

ORAUT-TKBS-0010-6, Technical Basis Document for Los Alamos National Laboratory – 

Occupational External Dose, Rev. 00; May 10, 2005; SRDB Ref ID: 19566 

Bayo, Estimates of Materials at the Bayo Canyon Firing Sites; author unknown; date unknown; Los 

Alamos Scientific Laboratory; SRDB RefID: 7895 

Chelius, 1970, memo from L.G. Chelius to H.J. Blackwell; Radioactive Effluents and Releases; Los 

Alamos Scientific Laboratory; April 10, 1970; SRDB Ref ID: 28829 

Dummer, 1961, Iodine Activity from DP West Hot Cells, Compilation of Office Memoranda; J. E. 

Drummer; Los Alamos Scientific Laboratory; 1961; SRDB Ref ID: 14523 

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Glasstone p. 481-3, Sourcebook on Atomic Energy, Third Edition; Samuel Glasstone; D. van Nostrand 

Company, Inc.; New York; 1967; SRDB Ref ID: Not available in the SRDB - publicly available 

Groves, p. 110, Now It Can Be Told, Leslie R Groves; Harper and Brothers, New York; 1962; SRDB 

Ref ID: Not available in the SRDB - publicly available 

Hacker p. 200-205, Elements of Controversy: The Atomic Energy Commission and Radiation Safety in 

Nuclear Weapons Testing 1947-1974; Barton C. Hacker; Berkeley/Los Angeles/London: University 

of California Press; 1994; SRDB Ref ID: Not available in the SRDB - publicly available 

Healy, 1970, Los Alamos Handbook of Radiation Monitoring; J. W. Healy; Los Alamos Scientific 

Laboratory; 1970; SRDB Ref ID: 943 

Hempelmann, 1945, History of the Health Group (A-6) (March 1942 - November 1945), L. H. 

Hempelmann, MD; LANL; 1945; SRDB Ref ID: 12894 

Hewlett and Anderson, pp. 164, 212, 229-230, 243-245; The New World 1939/1946. Volume 1 of A 

History of the United States Atomic Energy Commission; Richard G. Hewlett and Oscar E. Anderson, 

Jr.; University Park: The Pennsylvania State University Press; 1962; SRDB Ref ID: Not available in 

the SRDB - publicly available 

Hewlett and Duncan, pp. 583-4; Atomic Shield 1947/1952. Volume 2 of A History of the United 

States Atomic Energy Commission; Richard G. Hewlett and Francis Duncan; U. S. Atomic Energy 

Commission Report; WASH 1215; 1972; SRDB Ref ID: Not available in the SRDB - publicly 

available 

Kathren, Gough and Benefiel, pp. 277-8, The Plutonium Story: The Journals of Professor Glenn T. 

Seaborg 1939-1946; Ronald L. Kathren, Jerry B. Gough, and Gary T. Benefiel, Editors; Columbus: 

Battelle Press; 1994; SRDB Ref ID: Not available in the SRDB - publicly available 

LANL, 2000, A Review of Criticality Accidents; 2000 Revision; LA-13638; May, 2000; SRDB Ref 

ID: 895 

LANL, 2004, Annual Worker Deep, Neutron, Shallow, and Collective Dose Values Supplied by 

LANL for 1944 through Part of 2004; Los Alamos National Laboratory; SRDB Ref ID: 27261 

LANL PEB, 1986, Photodosimetry Evaluation Book, Volume IVb, 1981-1986; Los Alamos Scientific 

Laboratory; 1986; SRDB Ref ID: 8209 

LANL PEB, 1989, Photodosimetry Evaluation Book, Volume VI, 1989; Los Alamos National 

Laboratory; 1989; SRDB Ref ID: 27288 

LANL PEB, 1996, Photodosimetry Evaluation Book, Volume VII, 1996; Los Alamos National 

Laboratory; 1996; SRDB Ref ID: 27273 

LANL PEB 2001, Photodosimetry Evaluation Book, Volume VIII, 1996-2001; Los Alamos National 

Laboratory; 2001; SRDB Ref ID: 27292 

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LANL PEB, 2003, Photodosimetry Evaluation Book, Volume IX, 2002-2003; Los Alamos National 

Laboratory; 2003; SRDB Ref ID: 27301 

LASL HD 1947, H-Division Progress Report, 20 October 1947 – 20 November 1947; LAMS-651; 

December 12, 1947; SRDB Ref ID: 7885 

LASL HD, 1949, Annual Report, Health Division, 1949; Thomas L. Shipman; Los Alamos Scientific 

Laboratory; February 28, 1950; SRDB Ref ID: 984 

LASL HD, 1951, Annual Report, Health Division, 1951; Thomas L. Shipman; Los Alamos Scientific 

Laboratory; May 12, 1952; SRDB Ref ID: 972 

LASL PEB, 1959, Photodosimetry Evaluation Book, Volume 1a; Los Alamos Scientific 

Laboratory; 1959; SRDB Ref ID: 8181 

LASL PEB, 1969, Photodosimetry Evaluation Book, Volume II, 1960-1969; Los Alamos 

Scientific Laboratory; 1969; SRDB Ref ID: 8173 

LASL PEB, 1977a, Photodosimetry Evaluation Book “Bible”, Volume III, 1970-1977; Los Alamos 

Scientific Laboratory; 1977; SRDB Ref ID: 8176 

LASL PEB, 1977b, Photodosimetry Evaluation Book, Volume IIIb, 1974-1977; Los Alamos 

Scientific Laboratory; 1977; SRDB Ref ID: 8192 

LASL PEB, 1979, Photodosimetry Evaluation Book, Volume 5, 1979; Los Alamos Scientific 

Laboratory; 1979; SRDB Ref ID: 27271 

LASL PEB, 1980, Photodosimetry Evaluation Book, Volume IVa, 1978-1980; Los Alamos 

Scientific Laboratory; 1980; SRDB Ref ID: 8206 

Lawrence, 1992, Internal memorandum from J. N. Lawrence to Internal Dosimetry; Volume 3 of 

Americium, Polonium, Uranium: Internal Doses from Uranium Urine Assays after 1991 Data; Los 

Alamos National Laboratory, May, 1992; SRDB Ref ID: 12932 

Littlejohn, 1960, Photodosimetry Procedures at Los Alamos; G. J. Littlejohn; Los Alamos Scientific 

Laboratory; August, 1960; SRDB Ref ID: 951 

Smyth 1945, p. 207, Atomic Energy for Military Purposes; Henry D. Smyth; Princeton: Princeton 

University Press; 1945; SRDB Ref ID: Not available in the SRDB - publicly available 

Tiger Team, 1991, Tiger Team Assessment of the Los Alamos National Laboratory; U. S. Department 

of Energy; Div. of Environment, Safety, and Health; November, 1991; SRDB RefID: 23620 

Vasilik, 1983, In Vivo Assessment of Whole Body Radioisotope Burdens at the Los Alamos National 

Laboratory; D. G. Vasilik and I. C. Aikin; Los Alamos National Laboratory; August, 1983; SRDB 

Ref ID: 925 

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Widner, 2003, Interviews and Personal Communications with J. N. P. Lawrence by T. E. Widner 

(2003); James N. P. Lawrence, former Los Alamos health physicist; documented by T.E. Widner of 

ChemRisk, Inc., and the ORAU Team; 2003; SRDB Ref ID: 27882 

Widner, 2004, Personal Communications Between Tom Widner and James N. P. Lawrence (2004); 

James N. P. Lawrence, former Los Alamos health physicist; documented by T.E. Widner of 

ChemRisk, Inc., and the ORAU Team; 2004; SRDB Ref ID: 27884 

Wingfield, 1974, Inventory of Quantities and Locations of Radioactivity in the Environment On and 

Near AEC Sites; Wingfield; Los Alamos Scientific Laboratory; 1974; SRDB Ref ID: 12978 

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