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SEC Petition Evaluation Report 

Petition SEC-00203 

Report Rev #: 0 Report Submittal Date: May 31, 2012 

Subject Expert(s): Jason Davis

Site Expert(s): N/A

Petitioner Administrative Summary

Petition Under Evaluation

Petition #

Petition 

Type

Petition A

Receipt Date DOE/AWE Facility Name

SEC-00203 83.14 May 30, 2012 Medina Modification Center

NIOSH-Proposed Class Definition

All employees of the Department of Energy, its predecessor agencies, and their contractors and 

subcontractors who worked at the Medina Modification Center in San Antonio, Texas, from January 

1, 1958 through December 31, 1966, for a number of work days aggregating at least 250 work days, 

occurring either solely under this employment or in combination with work days within the 

parameters established for one or more other classes of employees in the Special Exposure Cohort.

Related Petition Summary Information

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

N/A N/A N/A N/A

Related Evaluation Report Information

Report Title DOE/AWE Facility Name

N/A N/A

ORAU Lead Technical Evaluator: Jason Davis ORAU Peer Review Completed By: Daniel Stempfley

Peer Review Completed By: [Signature on File] 5/31/2012

Lara Hughes Date

SEC Petition Evaluation Reviewed By: [Signature on File] 6/1/2012

J. W. Neton Date

SEC Evaluation Approved By: [Signature on File] 6/1/2012

Stuart L. Hinnefeld Date
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Evaluation Report Summary: SEC-00203,

Medina Modification Center

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.

NIOSH-Proposed Class Definition 

All employees of the Department of Energy, its predecessor agencies, and their contractors and 

subcontractors who worked at the Medina Modification Center in San Antonio, Texas, from January 

1, 1958 through December 31, 1966, for a number of work days aggregating at least 250 work days, 

occurring either solely under this employment or in combination with work days within the 

parameters established for one or more other classes of employees included in the Special Exposure 

Cohort.

Feasibility of Dose Reconstruction Findings 

NIOSH initiated the review of the Medina Modification Center based on its operational relationship 

with the Pantex Plant in Amarillo, Texas, and the results of the SEC-00068 Pantex petition evaluation 

that culminated in the recommendation to add a class to the SEC. The Board, in its review of the 

SEC-00068 Pantex evaluation report, determined that access to process and source term information 

for various production activities was insufficient to support estimation of internal exposures for the 

period from January 1, 1958 through December 31, 1983. As in the case of Pantex, NIOSH has not 

located any information indicating that urinalysis or other forms of internal monitoring were 

conducted at the Medina Modification Center. 

NIOSH lacks sufficient information, which includes internal personnel monitoring data, air 

monitoring data, process data, and radiological source term information, to allow it to estimate with 

sufficient accuracy the potential internal exposures to uranium, plutonium, and tritium to which the 

proposed class may have been subjected. NIOSH finds that it is likely feasible to reconstruct external 

and occupational medical dose for Medina facility workers with sufficient accuracy. 

The NIOSH dose reconstruction feasibility findings are based on the following: 

Principal sources of internal radiation for members of the proposed class included exposures to 

tritium, enriched uranium, depleted uranium and plutonium during the assembly, inspection, and 

disassembly of weapons components, and to enhanced radon in structures that were required to 

safely test nuclear weapons or components. 

NIOSH has found indications that air monitoring for tritium and for alpha emissions was routinely 

performed. However, NIOSH has been unable to locate any recorded results of this monitoring. 
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NIOSH has access to information suggesting that baseline tritium urinalyses were performed for 

military personnel working in the plant and that these analyses were intended to be repeated every 

2-3 months. Mason and Hanger employees were also required to submit tritium urine samples as 

of April 1962. At the time of this writing, however, NIOSH does not have access to the results of 

the baseline urinalyses or any confirmation that the intended follow-up analyses were performed. 

NIOSH has not located any information suggesting that uranium or plutonium urinalyses were 

conducted. 

Principal sources of external radiation for members of the proposed class included exposures to 

enriched uranium, depleted uranium, and plutonium during the assembly, inspection, and 

disassembly of weapons components. 

NIOSH has access to individual external monitoring records and summary exposure records from 

the years 1959 through 1966. NIOSH intends to use neutron-to-photon ratios based on data from 

similar operations to support reconstructing external neutron doses for members of the proposed 

class. NIOSH has identified no information describing the medical X-ray examination 

requirements for the covered period at the site. Therefore NIOSH intends to use its available 

methodology and its knowledge of the technology of that era to support reconstructing medical Xray exposures for members of the proposed class. 

Based on this data availability, and the external and medical X-ray dose reconstruction methods 

available to NIOSH for the Medina Modification Center, NIOSH believes that it is possible to 

either: (1) estimate the maximum external 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 doses to members of the class more precisely than a 

maximum dose estimate. 

Pursuant to 42 C.F.R. § 83.13(c)(1), NIOSH determined that there is insufficient information to 

either: (1) 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 (2) estimate the radiation doses of members of the class more precisely 

than a maximum dose estimate. 

Although NIOSH found that it is not possible to completely reconstruct internal radiation doses for the 

proposed class, NIOSH intends to reconstruct external exposures and use any internal monitoring data 

that may become available for an individual claim (and that can be interpreted using existing NIOSH 

dose reconstruction processes or procedures). Therefore, dose reconstructions for individuals 

employed at the Medina Modification Center during the period from January 1, 1958 through 

December 31, 1966, but who do not qualify for inclusion in the SEC, may be performed using these 

data as appropriate. 

Health Endangerment Determination 

The NIOSH evaluation did not identify any evidence supplied by the petitioners or from other 

resources that would establish that the class was exposed to radiation during a discrete incident likely 

to have involved exceptionally high-level exposures, such as nuclear criticality incidents or other 

events involving similarly high levels of exposures. However, the evidence reviewed in this 
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evaluation indicates that some workers in the class may have accumulated chronic radiation exposures 

through intakes of uranium, plutonium, and tritium and from direct exposure to radioactive materials. 

Therefore, 42 C.F.R. § 83.13(c)(3)(ii) requires NIOSH to specify that health may have been 

endangered for those workers covered by this evaluation who were employed for a number of work 

days aggregating at least 250 work days within the 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. 
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Table of Contents 

Evaluation Report Summary: SEC-00203, Medina Modification Center ............................................... 3

1.0 Purpose and Scope ....................................................................................................................... 8

2.0 Introduction ................................................................................................................................. 8

3.0 NIOSH-Proposed Class Definition and Petition Basis ................................................................ 9

4.0 Radiological Operations Relevant to the Proposed Class ........................................................... 9

4.1 Operations Description ..................................................................................................... 10

4.2 Radiation Exposure Potential from Operations ................................................................ 11

4.3 Time Period Associated with Radiological Operations .................................................... 12

4.4 Site Locations Associated with Radiological Operations ................................................ 12

4.5 Job Descriptions Affected by Radiological Operations ................................................... 17

5.0 Summary of Available Monitoring Data for the Proposed Class .............................................. 17

5.1 Data Capture Efforts and Sources Reviewed ................................................................... 18

5.2 Worker Interviews ............................................................................................................ 18

5.3 Internal Personnel Monitoring Data ................................................................................. 18

5.4 External Personnel Monitoring Data ................................................................................ 19

5.5 Workplace Monitoring Data ............................................................................................. 21

5.6 Radiological Source Term Data ....................................................................................... 21

6.0 Feasibility of Dose Reconstruction for the Proposed Class ...................................................... 21

6.1 Feasibility of Estimating Internal Exposures ................................................................... 22

6.2 Feasibility of Estimating External Exposures .................................................................. 23

6.3 Class Parameters Associated with Infeasibility ................................................................ 23

7.0 Summary of Feasibility Findings for Petition SEC-00203 ........................................................ 24

8.0 Evaluation of Health Endangerment for Petition SEC-00203 ................................................... 25

9.0 NIOSH-Proposed Class for Petition SEC-00203 ...................................................................... 25

10.0 References ................................................................................................................................. 26

Attachment 1: Data Capture Synopsis ................................................................................................... 30
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SEC Petition Evaluation Report for SEC-00203

ATTRIBUTION AND ANNOTATION: This is a single-author document. All conclusions drawn from 

the data presented in this evaluation were made by the ORAU Team Lead Technical Evaluator: Jason 

Davis; Oak Ridge Associated Universities. The rationales for all conclusions in this document are 

explained in the associated text. 

1.0 Purpose and Scope

This report evaluates the feasibility of reconstructing doses for employees who worked at a specific 

facility during a specified time. It provides information and analysis 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, with the exception of the employee whose dose reconstruction could not be completed, and 

whose claim consequently led to this petition evaluation. The finding in this report is not the final 

determination as to whether or not the proposed class will be added to the SEC. This report will be 

considered by the Advisory Board on Radiation and Worker Health (the Board) and by the Secretary 

of Health and Human Services (HHS). The Secretary of HHS will make final decisions concerning 

whether or not to add one or more classes to the SEC in response to the petition addressed by this 

report. 

This evaluation, in which NIOSH provides its findings both on the feasibility of estimating radiation 

doses of members of this class with sufficient accuracy and on health endangerment, was conducted in 

accordance with the requirements of EEOICPA and 42 C.F.R. § 83.14.

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 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 proposed class of employees through NIOSH dose 

reconstructions.1

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 petitioners and the 

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

report, together with the petition, comments of the petitioner(s) and such other information as the 

Board considers appropriate, 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 

 

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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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 final decision process, the 

petitioner(s) may seek a review of certain types of final decisions issued by the Secretary of HHS.2

3.0 NIOSH-Proposed Class Definition and Petition Basis

NIOSH initiated the review of the Medina Modification Center based on its operational relationship 

with the Pantex Plant in Amarillo, Texas, and the results of the SEC-00068 Pantex petition evaluation 

that culminated in the recommendation to add a class to the SEC. The Board, in its review of the 

SEC-00068 Pantex evaluation report, determined that access to process and source term information 

for various production activities was insufficient to support estimation of internal exposures for the 

period from January 1, 1958 through December 31, 1983. As in the case of Pantex, NIOSH has not 

located any information indicating that urinalysis or other forms of internal monitoring were 

conducted at the Medina Modification Center. 

The NIOSH-proposed class includes all employees of the Department of Energy, its predecessor 

agencies, and their contractors and subcontractors who worked at the Medina Modification Center in 

San Antonio, Texas from January 1, 1958 through December 31, 1966, for a number of work days 

aggregating at least 250 work days, occurring either solely under this employment or in combination 

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

Special Exposure Cohort. During this period, employees at this facility were involved in the storage, 

maintenance, assembly, and disassembly of uranium and plutonium weapons. 

The evaluation responds to Petition SEC-00203 which was submitted by an EEOICPA claimant 

whose dose reconstruction could not be completed by NIOSH due to a lack of sufficient dosimetryrelated information. NIOSH’s determination that it is unable to complete a dose reconstruction for an 

EEOICPA claimant is a qualified basis for submitting an SEC petition pursuant to 42 C.F.R. § 

83.9(b). 

4.0 Radiological Operations Relevant to the Proposed Class 

The following subsections summarize the radiological operations at the Medina Modification Center 

from January 1, 1958 through December 31, 1966 and the information available to NIOSH to 

characterize particular processes and radioactive source materials. Using available sources, NIOSH 

has attempted to gather process and source descriptions, information regarding the identity and 

quantities of radionuclides of concern, and information describing processes through which the 

radiation exposures of concern may have occurred and the physical environment in which they may 

have occurred. The information included within this evaluation report is meant only to be a summary 

of the available information. 

 

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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4.1 Operations Description 

The Medina Modification Center was located in San Antonio, Texas on 3,700 acres of land southwest 

of Lackland AFB, the training center for most Air Force recruits (Lamb, 1995). For the period 

evaluated by NIOSH, the Medina workforce ranged from a minimum of approximately 95 workers in 

1959 to a maximum of 669 workers in 1963. This total then declined to approximately 600 workers in 

1965 and 1966 as the facility was nearing closure (Mason, 1966; MED-142, 1970; Tracerlab, 1959; 

Tracerlab 1960; Tracerlab, 1961; Tracerlab, 1962; Tracerlab, 1963; Tracerlab, 1964; Tracerlab, 

1965). 

The Air Force’s Medina Modification Center was a sister facility to the Clarksville Modification 

Center, and the two provided similar services to the Department of Defense (DOD) as National 

Stockpile Sites. Beginning in 1954 and finishing in 1955, the Atomic Energy Commission (AEC) and 

the Air Force constructed the Medina facility with the code name Site King (Maroncelli, 2002). The 

AEC reserved most of the acreage at the Medina facility for about 100 earth-covered ammunition 

igloos arranged in orderly columns across the north-central portion of the site. The military began 

shipping nuclear warheads there in 1955, and Sandia Corporation specialists managed the day-to-day 

operations. The AEC shared operation of the facility with the Air Force for five years. The sole 

mission of the facility during this period was the storage, maintenance, and control of a portion of the 

nation’s nuclear stockpile (Lamb, 1995). 

By the late 1950s, the nuclear weapons workers at the Pantex Plant and the Iowa Ordnance Plant were 

struggling to meet production demands. In 1958, the AEC chose Mason & Hanger to operate the 

Medina facility, designated it the Medina Modification Center, and constructed substantial new 

facilities. The AEC also discontinued storage of nuclear weapons at Medina and concentrated solely 

on the disassembly and modification plants (Maroncelli, 2002).

By 1960, Sandia personnel had left the facility, and Mason & Hanger had taken over the warhead 

modification activities. The two principal missions of the Medina Modification Center were stockpile 

surveillance and protection, and weapon modification, retrofit, and retirement. This vital work 

included routine inspections for corrosion, tritium leaks, and permissive action link reliability; and 

replacement of short-lived initiators with fresh Po-210 or tritium. In some cases, technicians tested 

specific weapon components to destruction, replaced obsolete parts with up-to-date technology, or 

retired the weapon completely from the active stockpile. Also, DOD requested Medina specialists to 

examine and assess nuclear weapons that had been damaged or destroyed by accidental dropping, 

plane crashes, fires, or other mishaps. The AEC grouped the Medina Modification Center buildings 

into three large compounds and surrounded them with multiple fences and vegetation-cleared buffer 

zones. The site made use of three dome-shaped Gravel Gerties, ten storage buildings, various other 

support structures, landfills, and burial areas (Maroncelli, 2002).

In January 1965, the AEC designated the Medina Modification Center as a branch of its new Amarillo 

Area Office. In 1966, the Air Force reacquired the facility and renamed it the Lackland AFB Training 

Annex (LTA) (Lamb, 1995). Since then, various training units and intelligence and cryptologic 

operations have used the facilities. Today, the LTA remains off-limits to visitors without official 

permission and a need to be there. The modification buildings and Gravel Gerties are still in place in 

varying states of use. 
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Notable Radiological Incidents During the Period Under Evaluation 

September 10, 1959: Ir-192 Source Exposure 

A vendor came to the site to demonstrate a new type of portable, air-operated radiography 

source/shield (apparently called a Puff camera). The device could pneumatically transfer a source 

from the safe shielded position, through a 30-ft tube, to a radiography exposure location to X-ray an 

electronic part. The vendor representative and the Medina radiography staff successfully 

demonstrated moving the capsule out to the end of the tube and back into the lead shield using a 

nonradioactive dummy. When the vendor representative was leaving the site, he realized he did not 

have the dummy capsule and returned. An investigation revealed that the dummy was still in the lead 

shield and when the air flow was reversed, the 30-Ci Ir-192 source could not enter the shield because 

the dummy was there. When the air flow stopped, the Ir-192 source fell onto the ground near the 

radiographers. As a result, three individuals received unusually high gamma radiation exposures: 

Radiographer A – 6,600 mrem; Radiographer B – 3,000 mrem; and Radiographer C – 1,730 mrem. 

These exposures are included in the summarized records (Mason, 1959).

November 13, 1963: Detonations of High-Explosive Assemblies 

Three Mason & Hangar technicians were loading chemical high-explosive assemblies into an 

ammunition storage igloo when a spark ignited the assemblies and they began to burn uncontrollably. 

About 45 seconds later, the burning assemblies detonated, setting off additional high-explosive 

assemblies. The blast from the high explosives created a 20-foot deep crater and a shock wave that 

broke windows 12 miles away in downtown San Antonio and was audible at least 50 miles away. 

Several thousand pounds of natural and depleted uranium stored in the igloo disintegrated and 

dispersed irretrievably into the atmosphere. The three technicians were not seriously injured; damage 

at the modification center was limited to broken windows. The Texas State Department of Health and 

the U.S. Public Health Service performed radiological surveys and sampling on site and downwind. 

The AEC also dispatched a radiologically-instrumented EG&G company aircraft from Colorado to 

survey hundreds of square miles of the San Antonio metropolitan area. The EG&G and PHS staff 

reported no radiation detectable above background levels and no traces of the vaporized uranium 

(Guillou, 1964; Rademacher, 2000).

4.2 Radiation Exposure Potential from Operations 

The potential for external radiation dose existed throughout the Medina Modification Center. Based 

on the site operations outlined in Section 4.1, sources of exposure included beta, gamma, and neutrons 

emitted from plutonium and uranium, and from polonium initiators as well as from an iridium and a 

cobalt radiography source. 

The primary sources of internal radiation exposure at the site were airborne uranium oxide and tritium 

gases generated during inspection assembly and disassembly of weapons and components, and 

enhanced radon in structures that were required to safely test nuclear weapons or components 

(Crismon, 1960; Higgins, 1960; Lamb, 1995). The exposure potential from plutonium was likely 

small, as the plutonium containing components consisted of clad or plated parts. 
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4.3 Time Period Associated with Radiological Operations 

Per the DOE Office of Health, Safety and Security, the time period associated with DOE operations at 

the Medina Modification Center is from 1958-1966 (DOE, 2010). Operations at the Medina facility 

ceased in 1965 when the processes were transferred to the Pantex Plant (Lamb, 1995) and structures 

were released piecemeal as they were cleaned and decontaminated (Plan, 1966). NIOSH has 

documentation indicating that all radiological materials were removed from the site and disposed of in 

accordance with an approved close-down plan, and all buildings had been cleaned and decontaminated 

as of the February 15, 1966 evaluation (Vespe, 1966). However, decontamination of certain areas of 

the facility (e.g., the burn pit) was not scheduled for completion until after the March 7, 1966 release 

from production (Plan, 1966). Because the completion date for final decontamination is not clear, 

NIOSH proposes that the class period match the facility’s covered period of January 1, 1958 through 

December 31, 1966. 

 

4.4 Site Locations Associated with Radiological Operations 

At the Medina Modification Center, specific types of activities were carried out in locations or 

buildings designed for that purpose. The following subsections describe the various categories of 

locations/buildings. 

“A” Structures 

Buildings 301, 402, 403, 404, 552, 556, 562, 566, 571, and 585, known as "A" Structures, were used 

to store nuclear capsules for weapons systems. These buildings, though massive concrete structures, 

contained only four small storage rooms. Each room was approximately 10 feet wide, 13 feet deep 

and 9 feet high. Each room had the capacity to hold approximately 30 capsules in their "critically 

safe" storage containers. These storage rooms were accessed through bank-vault-type doors equipped 

with dual combination locks (Lamb, 1995).

Ten-foot-thick walls and massive berming were designed to shield the capsules stored in the vaults 

from external attacks, rather than as containment of possible accidental detonations. A sophisticated 

external device was required to arm the capsules, so there was little possibility of an explosion 

occurring within the structure (Lamb, 1995).

Spacing of the capsules stored in the" A" Structures was designed to prevent nuclear criticality. 

Although capsules stored closely together would not have detonated, they would have generated a 

burst of neutrons and endangered maintenance personnel. Storage containers for the capsules were 

designed to prevent any such accident from occurring. The capsule storage containers consisted of a 

cylinder approximately 14 inches in diameter and approximately 25 inches in height. Steel braces, 

welded to the top, bottom, and sides of the cylinder created a frame larger than the cylinder itself. The 

finished container assemblies were called "bird cages.” They were sealed with lead-wire seals 

(similar to those used to prevent tampering with electrical power meters) to ensure that their contents 

were not disturbed between authorized maintenance activities (Lamb, 1995).
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Maintenance activities always took place in a "C” Structure and never in the vault where the capsules 

were stored. Therefore, no nuclear material was ever exposed within an "A" Structure and there was 

little or no potential for any release of radioactive material within this building. Activities within the 

"A" Structure ceased in 1960 (Lamb, 1995). 

“C” Structure 

Building 307, known as a "C” Structure, was used as a nuclear materials inspection 

laboratory/maintenance building for the first nuclear weapons stored at Medina facility. The building 

was constructed prior to the arrival of special weapons in 1955. The "C” Structure provided bench 

space to perform required maintenance operations, storage for neutron calibration and assay sources, 

and support facilities that included a change room and storage areas. Nuclear capsules removed from 

“A” structures for maintenance were transported in their bird cages (Lamb, 1995).

Early weapons used polonium-beryllium initiators to generate neutrons during the explosion 

sequence. Because Po-210 has a half-life of approximately 138 days, the initiators had to be replaced 

periodically. According to former Sandia National Laboratory personnel, these devices were 

maintained following precise quality control methods that required the following steps (Lamb, 1995):

1. Release pressure from the bird cage container through a filter and check the filter for alpha 

activity; if no activity, remove capsule from the container using a handling tool. 

2. Place the capsule on a table top with an alpha probe at one end. (The table was covered with a 

large piece of butcher paper to contain any spalling of uranium oxides.) 

3. Place a Plexiglas glove box over the capsule. 

4. Disassemble the capsule parts and check the integrity of the coatings. 

5. Remove the glove box. 

6. Remove uranium oxide deposits from the threads using a small cloth or paper swipe and 

trichloroethylene (TCE). Wipe off the threads with ethyl alcohol to dry the components. 

7. Use acetone to remove previous markings made with blue machinist's dye and make new 

markings. (Later components had serial numbers etched on the surface of the components.) 

8. Check the activity of the fissile material using beta and gamma radiation measurements. 

9. Assay the nuclear material by accurately weighing it; perform sub-critical multiplication 

measurements using external neutron sources. 

10. Replace the polonium-beryllium initiators. (These were later replaced with nonradioactive 

initiators.) 

11. Reassemble the capsule. 
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12. Place the capsule and a sack of desiccant in the bird cage container. 

13. Screw on the bird cage container top. Re-pressurize and wire seal the bird cage container. 

(Positive pressure was maintained to ensure dryness and keep the O-rings in place). 

After maintenance activities in the "C" Structure were completed, the used initiators were sent to Los 

Alamos National Laboratory (LANL) in New Mexico, for storage, regeneration, or disposal. The 

spalled uranium oxides, swipes contaminated with solvents, lead-wire seals, and gloves were wrapped 

in the butcher paper and placed in 18 x 18 x 24-inch cardboard boxes. The boxes were presumably 

disposed of in the dry Low-Level Radioactive Waste (LLRW) disposal area (currently RW-17). 

Documentation indicates that this area received no free liquid waste (Lamb, 1995).

A source safe (a cylindrical apparatus located below the floor surface, with a polyethylene neutron 

absorber at the top) was located in the corner of the laboratory room of the "C" Structure. Below the 

neutron absorber, the source safe had a tray for storing check sources used to verify the activity of the 

fissile material in the weapons (Lamb, 1995).

No accidental releases of plutonium are known to have occurred at Medina Modification Center 

during the AEC's tenure. Based on sampling performed during closeout and events, there are no 

indications that any spills or releases of radioactive material occurred in the "C" Structure during its 

operational lifetime (Lamb, 1995).

Between 1954 and 1957, the polonium/beryllium initiators were phased out and replaced with a newer 

type of sealed neutron initiator which did not require routine replacement. Maintenance activities 

were reduced to annual disassembly of capsules to determine their condition and to verify the integrity 

of the fissile materials. Maintenance of the newer capsules generated the same types of waste, but in 

smaller quantities because of the infrequent maintenance schedule. By approximately 1960, capsules 

had been phased out of the stockpile and maintenance activities at Building 7418 ceased. Thereafter, 

AEC maintenance activities did not involve any exposed nuclear material (Lamb, 1995).

Assembly and Maintenance Buildings 

Plants 1 and 2 each consisted of a set of two buildings originally constructed to maintain nonnuclear 

components of weapons stored at the Medina facility. Early activities in the plants included 

inspection, testing, and assembly of nonnuclear mechanical and electrical systems (Lamb, 1995). The 

plants were renovated in 1959 to become more of an integral part of the Medina Modification Center 

(Davis, 1999). 

Plant 1 consisted of a mechanical bay (M-Bay), electrical bay (E-Bay), and plutonium assembly cell 

(gravel gertie). The M-Bay was used for the inspection, repair, modification, assembly, disassembly, 

and salvage of uranium weapons. Some assembly and disassembly of the outer cases of plutonium 

weapons were also conducted in the M-Bay. However, the majority of plutonium operations were 

carried out in the gravel gertie. A maximum of 20 kg of plutonium was permitted in the M-Bay at any 

one time (Davis, 1961). 
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E-Bay was used for the inspection, testing, and modification of electrical components. This bay 

contained a small pit inspection and weighing room where both uranium and plutonium pits would be 

removed from carrying cases, inspected, and weighed. Documentation suggests that alpha monitoring 

and the badging of all personnel present were both required during inspection activities. Additionally, 

swipes were taken of all of the nuclear components, bird cages, tools, and equipment used. The 

individuals performing the inspections as well as the work spaces were surveyed for alpha 

contamination after each inspection (Davis, 1999, Davis, 1961). E–Bay also contained a tritium 

reservoir room where squib valves could be assembled and disassembled under a ventilated hood 

(Davis, 1961). 

Plant 2 consisted of one E-Bay, one M-Bay and two gravel gerties, each with functions similar to their 

counterparts in Plant 1. In addition, Plant 2 had an Auxiliary Process Building (Building 444) that had 

eight work bays with six being used for general weapons assembly, disassembly, and modification. 

This building had plutonium limit of 20 kg present at any one time, similar to the M-Bays (Davis, 

1961). 

Gravel gerties (Buildings 440, 441, and 433) got their names from the several tons of gravel that were 

present in the ceiling of the structure for containment of fissile material in the event of an accidental 

detonation of the high-explosive system (Lamb, 1995). The gerties were composed of five bays with 

a material limit of five complete weapons units per bay. One of the five bays was used for inspection 

and repair of weapons containing plutonium pits. Another bay was used for removing the high 

explosives from plutonium pits. Two bays were used as staging areas and one main bay was used as 

the main assembly bay (Davis, 1960). Use of the gravel gertie modification/disassembly plants 

ceased in 1965 (Lamb, 1995).

“S” Structure 

An "S" (or Surveillance) Structure was constructed at Medina in 1955 for quality assurance 

inspections and for the testing of weapons in the stockpile at that time. Quality Assurance (QA)

activities were the responsibility of the SNL Quality Assurance Inspection Agency (QAIA). This "S" 

Structure was constructed in order to separate QA activities from the routine maintenance and 

assembly functions performed at Plants 1 and 2. This building was modified as part of the 

modification/disassembly center in 1959 (Lamb, 1995). After this time, weapons and components 

were inspected and tested in the M- and E-Bays of this structure. Alpha monitoring was in place 

during these operations (Davis, 1961). 

Storage Igloos 

One hundred standard igloos were constructed at Medina for the storage of weapon components, 

assembled weapons, and weapon casings (Lamb, 1995). Igloo No. 521 was used as a radiographic 

building with a 150-300 keV X-ray unit and a Model 150 Multitron with a 100-Ci Co-60 source that 

was routinely used. A 30-Ci iridium radiography source with puff camera was used in this building 

prior to 1961. This building was equipped with a fixed gamma alarm. Personnel were required to 

wear film dosimetry and carry a portable beta/gamma monitor when entering the building (Davis, 

1961). 
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Igloos 522 and 523 were temporarily used as operating structures when the plant workloads became 

too high. Igloos 519 through 523, 547, and 559 were used as centers for packaging and temporary 

storage of materials for the plant (Davis, 1961). 

Igloo 529 and 553 were used for the storage of weapon pits and tritium reservoirs. These materials 

were stored in their shipping containers to minimize contamination and criticality risks. Secondary 

weapon capsule assemblies were stored in Igloo No. 530. Weapons accident wastes and residues were 

stored in Igloos 528 and 584. It was noted that, during storage, some of the containers of residues had 

begun to rust and flake, leading to some low-level alpha contamination in these areas (Davis, 1961). 

Igloo 547 was used for the teardown of Mark 6-type weapons (Davis, 1961). 

Modification and Disassembly Plants 

In 1959, the AEC built a facility at Medina for modifying and disassembling weapons. This facility 

was comprised of three gravel gerties (Buildings 440, 441, and 433). High-explosive shells were 

removed from nuclear assemblies within this structure. Several tons of gravel was present in the 

ceiling of the structure for containment of fissile material in the event of an accidental detonation. Use 

of the gravel gertie modification/disassembly plants ceased in 1965 (Lamb, 1995).

Low-Level Radioactive Waste (LLRW) Disposal Areas 

Three sites at Medina (PW-15, RW-17, and RW-19) were reportedly designed for the collection of dry 

and liquid LLRW. RW-15 was a landfill used for the disposal of LLRW from Medina and (according 

to documentation) from Sandia (Miller, 1962). The landfill may have received classified, limited-life 

components disposed of during weapons modification and disassembly operations between 1959 and 

1965 (Lamb, 1995). Documentation suggests that detailed inventories were kept of all material stored 

in these landfills; however, NIOSH does not have access to these inventories (Miller, 1962). 

Based on information collected by Lackland AFB, the waste was stored below ground in wooden 

crates (approximately 4 x 4 x 8-feet deep) with radioactive warning signs affixed to crate exteriors. 

The crates were excavated in 1965 and removed from the area when AEC operations ceased. The site 

was cleared by federal safety personnel as being decontaminated when AEC closed operations (Lamb, 

1995).

The dry LLRW generated in the "C" Structure (e.g., swipes, butcher paper, gloves) was typically 

contained in 18 x 18 x 24-inch cardboard boxes. The boxes presumably were disposed of on site in 

the LLRW disposal area known as IRP site RW-l7. RW-17 was an unlined pit measuring 4 x 10 x 

6-feet deep (Lamb, 1995).

A former AEC employee indicates that RW-19 was a small gravel leaching area (approximately 20 x 

20 feet) located behind Building 444. The site reportedly received intermittent waste water discharges 

from Building 444. The waste water may have contained LLRW from this building. Gravel and soil 

from the area were excavated from the site when the AEC left Medina in 1965 (Lamb, 1995). 
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Although the above-listed areas are specifically identified for the use of AEC-related radiological 

materials, documentation available to NIOSH does not indicate any definite boundaries between 

radiological and non-radiological areas for the period being evaluated. Furthermore, documentation 

available to NIOSH also does not indicate that the above-listed areas are the only ones in which 

radiological materials were handled. 

NIOSH has determined that the site-specific and claimant-specific data available for the time period of 

this evaluation are insufficient to allow NIOSH to characterize worker movements across the Medina 

site. NIOSH is therefore unable to define individual worker exposure scenarios based on specific 

work locations within the Medina Modification Center during the period under evaluation. 

4.5 Job Descriptions Affected by Radiological Operations 

NIOSH has determined that the site-specific and claimant-specific data available for Medina 

Modification Center for the time period under evaluation are insufficient to allow NIOSH to 

determine that any specific work group was not potentially exposed to radioactive material releases or 

possible subsequent contamination. 

NIOSH has insufficient information associating job titles and/or job assignments with specific 

radiological operations or conditions. Without such information, NIOSH is unable to define potential 

radiation exposure conditions based on worker job descriptions. 

5.0 Summary of Available Monitoring Data for the Proposed Class

The primary data used for determining internal exposures are derived from personal monitoring data, 

such as urinalyses, fecal samples, and whole-body counting results. If these are unavailable, the air 

monitoring data from breathing zone and general area monitoring are used to estimate the potential 

internal exposure. If 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. 

This same hierarchy is used for determining the external exposures to the cancer site. Personal 

monitoring data from film badges or thermoluminescent dosimeters (TLDs) are the primary data used 

to determine such external exposures. If there are no personal monitoring data, exposure rate surveys, 

process knowledge, and source term modeling can sometimes be used to reconstruct the potential 

exposure. 

A more detailed discussion of the information required for dose reconstruction can be found in 

OCAS-IG-001, External Dose Reconstruction Implementation Guideline, and OCAS-IG-002, Internal 

Dose Reconstruction Implementation Guideline. These documents are available at: 

http://www.cdc.gov/niosh/ocas/ocasdose.html. 
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5.1 Data Capture Efforts and Sources Reviewed 

As a standard practice, NIOSH completed an extensive database and Internet search for information 

regarding the Medina Modification Center. The database search included the DOE Legacy 

Management Considered Sites database, the DOE Office of Scientific and Technical Information 

(OSTI) database, the Energy Citations database, and the Hanford Declassified Document Retrieval 

System. In addition to general Internet searches, the NIOSH Internet search included OSTI OpenNet 

Advanced searches, OSTI Information Bridge Fielded searches, Nuclear Regulatory Commission 

(NRC) Agency-wide Documents Access and Management (ADAMS) web searches, the DOE Office 

of Human Radiation Experiments website, and the DOE-National Nuclear Security AdministrationNevada Site Office-search. Attachment 1 contains a summary of the Medina Modification Center 

documents. The summary specifically identifies data capture details and general descriptions of the 

documents retrieved. 

NIOSH is awaiting responses from the Fort Worth Federal Records Center and Mason and Hanger 

Corporation for access to some information regarding the Medina Modification Center. However, 

after review of the outstanding document titles by the DCAS Health Physics Lead Evaluator and 

DCAS Director, NIOSH feels that these documents would not provide any information that would 

change the feasibility determination for this site. 

In addition to the database and Internet searches listed above, NIOSH identified and reviewed 

numerous data sources to determine information relevant to determining the feasibility of dose 

reconstruction for the class of employees under evaluation. 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. 

5.2 Worker Interviews 

Based on its reviews of the NOCTS files and information/documentation in the SRDB, NIOSH 

identified no obvious interview candidate for this evaluation.

5.3 Internal Personnel Monitoring Data 

Documentation available to NIOSH indicates that an industrial medicine program was in place, 

including a part-time physician from the Minter Clinic as well as a registered nurse and a registered 

laboratory technician. The dispensary was located in Building 111 and contained a first-aid room and 

laboratory facilities (Miller, 1962). This building contained facilities for the performance of tritium 

urinalysis. NIOSH has access to information suggesting that baseline tritium urinalyses were 

performed for military personnel working in the plant and that these analyses were intended to be 

repeated every 2-3 months (Davis, 1999). Mason and Hanger employees were also required to submit 

urine samples as of April 1962 (Vespe, 1966). At the time of this writing, NIOSH does not have 

access to the results of the baseline tritium urinalyses or any confirmation that the intended follow-up 

tritium analyses were performed. NIOSH has not located any information suggesting that uranium or 

plutonium urinalyses were conducted. 
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NIOSH found indications that air monitoring for tritium and for alpha emissions were routinely 

performed (Blackwell, 1960; Davis, 1960; Davis, 1999; Higgins, 1960). However, NIOSH has been 

unable to locate any recorded results of this monitoring. 

The NOCTS database was reviewed for claimants whose work history included the Medina 

Modification Center during part or all of the covered period (1958 through 1966). A total of 47 

claimants were identified. The files for 47 claimants were thoroughly reviewed and no internal 

monitoring data were found. This is consistent with above determination that insufficient monitoring 

existed. 

5.4 External Personnel Monitoring Data 

Mason & Hanger used weekly dosimetry services provided by Tracerlab from April 1959 until July 

1964. From July 1964 until January 1966, weekly dosimeters were provided by Nuclear Service 

Laboratories of Knoxville, Tennessee (Everett, 1964). The clerical maintenance of the dosimetry 

records was not rigorous. For example, individual names were consistently assigned to only a 

maximum of eleven film badge numbers and some numbers were reused when an individual left the 

program. Over 100 other film badges were assigned to different people each week and the individual 

names, for non-zero results only, were then recorded on the film badge dose report after it was 

received. Some weeks, the task of recording names associated with non-zero dose results was not 

completed, so it is impossible to reconstruct who received the non-zero doses. Because more than one 

individual was assigned to a given film badge number, the quarterly and annual totals maintained by 

the film badge processor were not useful. 

The records contained hand-written tally sheets for 1959, 1960, 1961, and 1962 that showed the 

dosimetry records were routinely transcribed to maintain individual dose totals by calendar quarter, 

calendar year, and total Medina doses. These records were later compiled by computer and printed 

each quarter during 1964 and 1965. Although the tally sheets for 1963 are missing from the records, 

the vendor dosimetry reports are available and appear to be complete and reasonably accurate. 

1959 Records: Only three individuals were consistently identified with assigned film badge 

numbers. There were also three visitor badges, but there were no notes as to whether the visitor 

badges were used or to whom they may have been assigned. Most of the reported results were less 

than the minimum reported dose (5 mrem for X-ray, 10 mrem for gamma, 30 mrem for beta, and 

15 mrem for neutron). There was no indication of the radiography incident of September 7, 1959 

(discussed in Section 4.1). (Tracerlab, 1959) 

1960 Records: Only three individuals were consistently identified with assigned film badge 

numbers through June 26, 1960. Beginning on June 27, 1960, seven individuals were consistently 

identified with assigned film badge numbers, and there were three visitor badges. There were no 

notes as to whether the visitor badges were used or to whom they may have been assigned. Most 

of the reported results were less than the minimum detectable dose. (Tracerlab, 1960) 
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1961 Records: Only seven individuals were consistently identified with assigned film badge 

numbers through July 2, 1961. As of July 3, 1961 there were only six individuals who were 

consistently identified with assigned film badge numbers, and there were four visitor badges. 

There were no notes as to whether the visitor badges were used or to whom they may have been 

assigned. Most of the reported results were less than the minimum detectable dose. (Tracerlab, 

1961) 

1962 Records: Only six individuals were consistently identified with assigned film badge 

numbers, and there were four visitor badges. There were no notes as to whether the visitor badges 

were used or to whom they may have been assigned. Most of the reported results were less than 

the minimum detectable dose. (Tracerlab, 1962) 

1963 Records: Only six individuals were consistently identified with assigned film badge numbers 

through June 2, 1963. As of June 3, 1963, there were 11 individuals consistently identified with 

assigned film badge numbers, and nine visitor badges. There were no notes as to whether the 

visitor badges were used or to whom they may have been assigned. As of November 18, 1963, 40 

more film badges were added to the service, but no individual names were associated with any of 

these badges. On December 16, 1963, 20 more film badges were added to the service for a total of 

60 badges with no assigned names. It was apparent that work activities increased significantly as 

of November 18, 1963, as there are non-zero results reported for X-ray or gamma and beta 

exposures. However, the non-zero results for the unidentified badges cannot be linked to any 

individuals. (Tracerlab, 1963) 

1964 Records: The records for early 1964 showed 11 individuals consistently identified with 

assigned film badge numbers, nine visitors, and 60 film badges with no names assigned. However, 

as of January 20, 1964, names were handwritten on the dosimetry report adjacent to the non-zero 

results. On the February 24, 1964 dosimetry report, names were handwritten adjacent to all the 

film badges issued, including the visitor badges, for a total of 72 names recorded. Also, 40 more 

twin-film badges (NTA film for neutrons) were added to the service. From March 2, 1964 

through April 19, 1964, names were recorded only with non-zero results. During this same period, 

there were many notes of spurious non-zero neutron results on badges that were not assigned to 

anyone. The 40 extra film badges with NTA film for neutrons were discontinued as of April 19, 

1964. On May 25, 1964, these 40 extra film badges with NTA film were added to the service. 

Through July 5, 1964, names were hand-written adjacent to all non-zero results. As of July 6, 

1964, Tracerlab film badges service (including NTA film) was discontinued and service (with no 

neutron monitoring) started with Nuclear Service Laboratories, Inc., of Knoxville, Tennessee. A 

total of 80 film badges were provided, with no individual names associated with any film badge 

number. In most (but not all) cases, names were handwritten adjacent to the non-zero results. On 

September 7, 1964, 20 more film badges were added to the service. A few dosimetry reports for 

Mason & Hanger employees who visited other sites during 1964 were included in the records; 

these data were added to the individual totals. (Tracerlab, 1964) 
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1965 Records: The records through June 27, 1965 showed 100 film badges provided but no names 

associated with any specific film badge number. In most (but not all) cases, names were 

handwritten adjacent to the non-zero results (X-ray or gamma only). As of June 28, 1965, the 

service was reduced to 67 film badges, still with no names identified with any specific film badge 

number. A few dosimetry reports for Mason & Hanger employees who visited other sites during 

1965 were included in the records; these data were added to the individual totals. (Tracerlab, 

1965)

1966 Records: Dosimetry service provided by Nuclear Service Laboratories was reduced to 25 

film badges as of January 3, 1966 and the service was terminated on January 24, 1966 when 

weapons-related work ended at Medina. There were no non-zero dosimeter results reported for 

1966. (Dose Records, 1966) 

5.5 Workplace Monitoring Data 

Although the NIOSH has indication that routine air monitoring, area monitoring, and contamination 

swipes were performed at Medina, NIOSH has not been able to recover the results of any of these 

activities or sufficient documentation of these practices (Blackwell, 1960; Davis, 1960b; Davis, 1999;

Higgins, 1960).

5.6 Radiological Source Term Data 

Routine operations at the Medina Modification Center involved uranium metals, uranium oxides, 

tritium, and plutonium. These materials were sources of potential exposure at the site. Given that 

these operations involved complete weapons, it is reasonable to assume that a detailed inventory was 

kept of the materials. However, NIOSH has been unable to locate a detailed inventory of the facility 

for the years under evaluation, possibly due to classification issues. No information regarding radon 

levels in the facility has been located by NIOSH. 

It is clear from the available research reports that Medina operations involved the use of uranium, 

tritium, and plutonium; however, the documentation does not provide sufficient information on 

specific radionuclides, quantities, or forms of the source materials used at any given time during the 

period under evaluation. Given this lack of information, NIOSH is unable to make reasonable 

assumptions about source terms, concentrations, or radiological equilibrium conditions at the Medina 

facility. 

6.0 Feasibility of Dose Reconstruction for the Proposed Class

42 C.F.R. § 83.14(b) states that HHS will consider a NIOSH determination that there was insufficient 

information to complete a dose reconstruction, as indicated in this present case, to be sufficient,

without further consideration, to conclude that it is not feasible to estimate the levels of radiation 

doses of individual members of the class with sufficient accuracy. 

In the case of a petition submitted to NIOSH under 42 C.F.R. § 83.9(b), NIOSH has already 

determined that a dose reconstruction cannot be completed for an employee at the DOE or AWE 
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facility. This determination by NIOSH provides the basis for the petition by the affected claimant. 

Per § 83.14(a), the NIOSH-proposed class defines those employees who, based on completed 

research, are similarly affected and for whom, as a class, dose reconstruction is similarly not feasible.

This section of the report summarizes research findings by which NIOSH determined that it lacked 

sufficient information to complete the relevant dose reconstruction and on which basis it has defined 

the class of employees for which dose reconstruction is not feasible. NIOSH’s determination relies on 

the same statutory and regulatory criteria that govern consideration of all SEC petitions. 

6.1 Feasibility of Estimating Internal Exposures 

NIOSH has evaluated the available personnel and workplace monitoring data and source term 

information and has determined that there are insufficient data for estimating internal exposures, as 

described below. 

NIOSH has access to information suggesting that baseline urinalyses were performed for military 

personnel working in the plant and that these analyses were intended to be repeated every 2-3 months 

(Davis, 1999). Mason and Hanger employees were also required to submit urine samples as of April 

1962 (Blackwell, 1962). However, at the time of this writing NIOSH does not have access to the 

results of these baseline urinalyses or any confirmation that the intended follow-up analyses were 

performed. NIOSH has not located any information suggesting that uranium or plutonium urinalyses 

were conducted. 

Although NIOSH has indication that routine air monitoring, area monitoring, and contamination 

swipes were performed at Medina, NIOSH has not been able to locate the results of any of these 

monitoring activities (Blackwell, 1960; Davis, 1960b; Davis, 1999; Higgins, 1960).

NIOSH has located very little documentation regarding the quantities of radiological materials 

shipped to Medina for processing or testing. It is clear from reports and worker communications that 

Medina worked with uranium, tritium, and plutonium. However, without additional documentation, 

ORAUT can make no assumption about what quantities of the source materials may have been used or 

stored on site at any time during the period under evaluation. 

In the absence of adequate internal dose monitoring criteria and adequate personnel monitoring data, 

NIOSH has not found sufficient general area air sampling, breathing zone air sampling, site survey, or 

source term information to allow it to bound potential exposures, or to demonstrate that workers were 

adequately monitored for potential exposures to radioactive materials at Medina during the period 

under evaluation. NIOSH has determined that reconstruction of the total internal doses received from 

exposures to uranium, uranium progeny, plutonium, and tritium is not feasible using the information 

available to NIOSH for the period from January 1, 1958 through December 31, 1966. 

Although NIOSH found that it is not possible to completely reconstruct internal radiation doses for the 

period from January 1, 1958 through December 31, 1966, NIOSH intends to use any internal 

monitoring data that may become available for an individual claim (and that can be interpreted using 

existing NIOSH dose reconstruction processes or procedures). Dose reconstructions for individuals 

employed at Medina Modification Center during the period from January 1, 1958 through December 
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31, 1966, but who do not qualify for inclusion in the SEC, may be performed using these data as 

appropriate. 

6.2 Feasibility of Estimating External Exposures 

This evaluation responds to a petition based on NIOSH determining that internal radiation exposures 

to uranium, plutonium, and tritium could not be reconstructed for a dose reconstruction referred to 

NIOSH by the Department of Labor (DOL). As noted above, HHS will consider this determination to 

be sufficient without further consideration to determine that it is not feasible to estimate the levels of 

radiation doses of individual members of the class with sufficient accuracy. Consequently, it is not 

necessary for NIOSH to fully evaluate the feasibility of reconstructing external radiation exposures for 

the class of workers covered by this report. 

NIOSH has access to individual external monitoring records and summary exposure records from the 

years 1959 through 1966 (Mason, 1966). The routine practice at Medina appears to have required 

assigning dosimeters to personnel designated as radiation workers who could receive an external 

radiation dose greater than 10% of the Radiation Protection Guidelines in effect. Because these 

individuals would have been the workers with direct exposure to the devices being maintained at the 

plant, it is reasonable to assume that these badges represent the maximally-exposed individuals. 

NIOSH intends to use neutron-to-photon ratios based on data from similar operations to support 

reconstructing external neutron doses for members of the proposed class. NIOSH has identified no 

information describing the medical X-ray examination requirements for the covered period at the site. 

Therefore, NIOSH intends to use its available methodology and its knowledge of the technology of 

that era to support reconstructing medical X-ray for members of the proposed class. 

Based on this data availability, and the external and medical X-ray dose reconstruction methods 

available to NIOSH for the Medina Modification Center, NIOSH believes that it is possible to either: 

(1) estimate the maximum external 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 doses to members of the class more precisely than a maximum dose 

estimate. 

6.3 Class Parameters Associated with Infeasibility 

As indicated in Section 4.3, NIOSH has documentation indicating that all radiological materials were 

removed from the site and disposed of in accordance with an approved close-down plan as of a 

February 15, 1966 evaluation. However, decontamination of certain areas of the facility (e.g., the 

burn pit) was not scheduled for completion until March 7, 1966 (Plan, 1966). Therefore, NIOSH 

recommends a class period from January 1, 1958 through December 31, 1966. 

As stated in Section 4.4, documentation available to NIOSH does not indicate any definite boundaries 

between radiological and non-radiological areas at the Medina Modification Center for the period 

under evaluation. NIOSH is therefore unable to define individual worker exposure scenarios based on 

specific work locations. NIOSH recommends that the class definition include all areas of the Medina 

facility during the specified time period. 
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As stated in Section 4.5, it is not possible to determine that any specific work group was not 

potentially exposed to radioactive material releases or possible subsequent contamination. Given the 

lack of information regarding job descriptions or associations between job titles and/or job 

assignments with specific radiological conditions, NIOSH recommends that the class include all 

workers who worked in any area at the site. 

7.0 Summary of Feasibility Findings for Petition SEC-00203

This report evaluates the feasibility for completing dose reconstructions for employees at the Medina 

Modification Center from January 1, 1958 through December 31, 1966. NIOSH determined that 

members of this class may have received radiation exposures from uranium, plutonium, and tritium. 

NIOSH lacks sufficient information, which includes monitoring data, sufficient air monitoring 

information, or sufficient process and radiological source information that would allow it to estimate 

the potential concentrations of plutonium, uranium, and tritium to which the proposed class may have 

been exposed. 

NIOSH has documented herein that it cannot complete the dose reconstruction related to this petition. 

The basis of this finding demonstrates that NIOSH does not have access to sufficient information to 

estimate either the maximum radiation dose incurred by any member of the class or to estimate such 

radiation doses more precisely than a maximum dose estimate. 

NIOSH has determined that adequate reconstruction of external exposures from all radionuclides, and 

occupational medical doses for this class of workers is considered likely to be feasible. 

Although NIOSH found that it is not possible to completely reconstruct radiation doses for the 

proposed class, NIOSH intends to reconstruct external exposures and use any internal monitoring data 

that may become available for an individual claim (and that can be interpreted using existing NIOSH 

dose reconstruction processes or procedures). Therefore, dose reconstructions for individuals 

employed at Medina Modification Center during the period from January 1, 1958 through December 

31, 1966, but who do not qualify for inclusion in the SEC, may be performed using these data as 

appropriate. 

NIOSH is awaiting responses from the Fort Worth Federal Records Center and Mason and Hanger 

Corporation for access to some information regarding the Medina Modification Center. However, 

after review of the outstanding document titles by the DCAS Health Physics Lead Evaluator and 

DCAS Director, NIOSH feels that these documents would not provide any information that would 

change the feasibility determination for this site. 
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8.0 Evaluation of Health Endangerment for Petition SEC-00203

The health endangerment determination for the class of employees covered by this evaluation report is 

governed by EEOICPA and 42 C.F.R. § 83.14(b) and § 83.13(c)(3). Pursuant to these requirements, if 

it is not feasible to estimate with sufficient accuracy radiation doses for members of the class, NIOSH 

must determine that there is a reasonable likelihood that such radiation doses may have endangered 

the health of members of the class. The regulations require 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 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 occurrence of such an exceptionally high-level exposure has not been established, 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. 

NIOSH has determined that members of the class were not exposed to radiation during a discrete 

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

criticality incidents. However, the evidence reviewed in this evaluation indicates that some workers in 

the class may have accumulated chronic radiation exposures through intakes of radionuclides and 

from direct exposure to radioactive materials. 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 the 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.

9.0 NIOSH-Proposed Class for Petition SEC-00203

The evaluation defines a single class of employees for which NIOSH cannot estimate radiation doses 

with sufficient accuracy. This class includes all employees of the Department of Energy, its 

predecessor agencies, and their contractors and subcontractors who worked at the Medina 

Modification Center in San Antonio, Texas from January 1, 1958 through December 31, 1966, for a 

number of work days aggregating at least 250 work days, occurring either solely under this 

employment or in combination with work days within the parameters established for one or more 

other classes of employees in the Special Exposure Cohort. 
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10.0 References

42 C.F.R. pt. 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. pt. 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. 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; 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; DCAS website 

Blackwell, 1960, Trip Report – Industrial Health Survey of San Antonio Area Office, H. J. Blackwell; 

March 31, 1960; SRDB Ref ID: 88915, pdf p. 14 

Blackwell, 1962, Industrial Health Survey, Medina Facility, March 22-23, 1962, H. J. Blackwell; 

April 19, 1962; SRDB Ref ID: 88915, pdf p. 51 

Crismon, 1960, T-289A Air Sampler Incident, W. Crismon Jr.; October 19, 1960; SRDB Ref ID: 

109275 

Davis,1960a , Trip Report Industrial Health Survey of San Antonio Area Office and Facilities – April 

1, 1960, C. E. Davis; April 26, 1960; SRDB Ref ID: 88915, pdf pp. 27-32 

Davis, 1960b, Trip Report – Industrial Health Survey of San Antonio Area Office and Contractor 

Facilities – September 22-23, 1960, C. E. Davis; October 24, 1960; SRDB Ref ID: 88915, pdf pp. 

39-43

Davis, 1961, Trip Report – Industrial Health Survey of San Antonio Area Office and Contractor 

Facilities – October 5-6, 1961, C. E. Davis; November 3, 1961; SRDB Ref ID: 88915, pdf pp. 9-13 

Davis, 1999, Report of Health Inspection – Medina Base, C. E. Davis, L. B. Hanson; March 9, 1999; 

SRDB Ref ID: 88915, pdf pp. 3-6 

DOE, 2010, DOE Facilities List Entry for the Medina Facility, U.S. Department of Energy Office of 

Health, Safety and Security; accessed May 14, 2012; http://www.hss.doe.gov/healthsafety/fwsp/ 

advocacy/faclist/ showfacility.cfm 

Dose Records, 1966, Medina Dose Records, 1959-1966; SRDB Ref ID: 24735

Everett, 1964, Trip Report September 17-18, 1964 – Industrial Health Survey of Medina Facility San 

Antonio, Texas, E. R. Mathews, C. E. Davis; SRDB Ref ID: 88915, pdf pp. 90-98 
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Guillou, 1964, Special Aerial Radiometric Survey Medina Base and Vicinity, R. B. Guillou; February 

7, 1964; SRDB Ref ID: 109291 

Higgins, 1960, Tritium Monitoring Requirements – Indoor Operations, J. M. Higgins; September 1, 

1960; SRDB Ref ID: 109242 

Lamb, 1995, Site Summary for the Lackland Air Force Base (Medina Base) Texas Former Weapons 

Storage Area, Lamb Associates, Inc.; December 1995; SRDB Ref ID: 24968 

Maroncelli, 2002, The Traveler’s Guide To Nuclear Weapons, A Journey Through America’s Cold 

War Battlefields, J. M. Maroncelli, T. L. Karpin; September 2002; SRDB Ref ID: 44825 

Mason, 1959, Contractor Report Radiation Exposure Incident September 10, 1959, Mason & HangerSilas Mason Co., Inc.; September 22, 1959; SRDB Ref ID: 109307

Mason, 1966, Pantex Plant Personnel Dosimetry Records, Mason & Hanger Facility At San Antonio, 

Mason & Hanger; by context, no earlier than 1966; SRDB Ref ID: 1289 

MED-142,1970, Pantex Plant Personnel Dosimetry Records – Medina, Mason & Hanger-Silas 

Mason Co., Inc., Mason & Hanger-Silas Mason Co.; by context, no earlier than 1970; SRDB Ref ID: 

1288

Medina, 1966, Medina Facility – Mason & Hanger Facility at San Antonio Radiation Exposure Data 

on Monitored Personnel Time Period 1961-1966; 1966; SRDB Ref ID: 1289, pdf pp. 3-10 

Miller, 1962, Industrial Health Survey, Medina Base, September 12, 13 and 14, 1962; R. L. Miller; 

October 8, 1962; SRDB Ref ID: 88915, pdf pp. 53-63

Plan, 1966, Safety Department Plan – Closedown Actions, March 7, 1966; SRDB Ref ID: 88920, pdf 

pp. 15, 18-21 

Rademacher, 2000, Radiological Scoping and Characterization Surveys Work Plan, 1963 Igloo 572 

Accident (Former Medina Base) Lackland Training Annex, Lackland Air Force Base, Texas, S. E. 

Rademacher; December 2000; SRDB Ref ID: 23255 

Tracerlab, 1959, Service Radiation Dosage Report, Tracerlab Inc.; 1959; SRDB Ref ID: 1274 

Tracerlab, 1960, Service Radiation Dosage Report, Tracerlab Inc.; 1960; SRDB Ref ID: 1277 

Tracerlab, 1961, Service Radiation Dosage Report, Tracerlab Inc.; 1961; SRDB Ref ID: 1279 

Tracerlab, 1962, Service Radiation Dosage Report, Tracerlab Inc.; 1962; SRDB Ref ID: 1281 

Tracerlab, 1963, Service Radiation Dosage Report, Tracerlab Inc.; 1963; SRDB Ref ID: 1282 

Tracerlab, 1964, Service Radiation Dosage Report, Tracerlab Inc.; 1964; SRDB Ref ID: 1283 
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Tracerlab, 1965, Service Radiation Dosage Report, Tracerlab Inc.; 1965; SRDB Ref ID: 1285 

Vespe, 1966, Health Protection Survey of Medina Facility, V. C. Vespe; February 24, 1966; SRDB 

Ref ID: 88920, pdf pp. 22-24 
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SEC-00203 05-31-12 Medina Modification Center 

Page 30 of 34 

Attachment 1: Data Capture Synopsis

Table A1-1: Data Capture Synopsis for the Medina Modification Center

Data Capture Information General Description of Documents Captured Date 

Completed

Uploaded

To SRDB

Primary Site / Company Name: Medina Facility; DOE 

1958-1966

Alternate Site Names: NA

Physical Size of the Site: 3,700 Acres

Site Population: Not located 

Radiological scoping and characterization survey work plan. Continuing 

effort with Mason & Hanger Corporation, Government Services, no 

records identified at this time.

OPEN 1

State Contacted: TX Department of State Health Service, 

Radiation Safety Licensing [Phone No. redacted]

No relevant documents identified. 04/18/2012 0

DOE Albuquerque Operations Office Burial of radioactive weapon residue, close-down plan for the Medina 

Facility, disposal of weapons residue, high explosive and plutonium 

limits, industrial health survey, MK 6 tear down, neutron dose detectors, 

neutron exposure evaluation, transfer of administrative control of 

Medina base, and a trip report.

09/13/2010 14

DOE Hanford Data classification decision 1946 to present. Awaiting response to 

Hanford Data Capture Activity 67. 

5/16/2012 1

DOE Legacy Management - Grand Junction Office Radioactive monuments for posterity. 02/10/2010 1

DOE Legacy Management - MoundView (Fernald 

Holdings, includes Fernald Legal Database)

Mound-vue article discussing shutdown of Medina. 05/18/2010 1

DOE Pacific Northwest National Laboratory (PNNL) Radiological scoping and characterization survey work plan. 04/02/2006 1

DOE Pantex Evacuation of building 12-26. Working with Department of Energy 

Point of Contact and site to access records at Fort Worth Federal 

Records Center and onsite.

OPEN 1

DOE Pantex / SC&A Contract AT(29-2)-756, "Scope of Work", burial of radioactive 

components and waste at Medina Facility, catalog of Medina Facility, 

change in tritium safety, cleanup of the burial grounds, radiation 

exposure incident, radiological survey, safety inspection, reports for 

weapon rebuild and repair, special aerial radiometric survey Medina 

base and vicinity, radiation safety procedures, and tritium monitoring 

while breaking gland nut connections.

06/23/2011 23

DOE Sandia National Laboratories, NM Lackland Air Force Base site summary and a list of Sandia reports on 

Pantex and Medina.

11/11/2010 4
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Table A1-1: Data Capture Synopsis for the Medina Modification Center

Data Capture Information General Description of Documents Captured Date 

Completed

Uploaded

To SRDB

Eastern Kentucky University Library Analysis of new Medina assembly cell, design and construction of 

Medina assembly cell facilities, criticisms of Clarksville branch 

operations, 1962 newsletters, Nuclear Weapon Safety Program for 

AEC-owned facilities, scrap disposal facility Medina base, and a safety 

policy.

05/07/2009 15

Internet - Defense Technical Information Center (DTIC) No relevant documents identified. 04/04/2012 0

Internet - DOE Comprehensive Epidemiologic Data 

Resource (CEDR)

No relevant documents identified. 04/10/2012 0

Internet - DOE Hanford Declassified Document Retrieval 

System (DDRS)

No relevant documents identified. 03/29/2012 0

Internet - DOE Legacy Management Considered Sites No relevant documents identified. 03/23/2012 0

Internet - DOE National Nuclear Security Administration 

(NNSA) - Nevada Site Office

No relevant documents identified. 04/02/2012 0

Internet - DOE OpenNet Defense nuclear agency historical documents lists, manufacturing 

statement for weapons production schedule of transfers, shipping report 

of assemblies, and a purchase order status report. NOTE: 3 documents 

added by Site Association Review.

03/29/2012 33

Internet - DOE OSTI Energy Citations Design progress report. 03/27/2012 1

Internet - DOE OSTI Information Bridge Missile accident site mitigation review. 03/27/2012 1

Internet - Google Annual report to Congress of the Atomic Energy Commission for 1964, 

traveler's guide to nuclear weapons, Environmental Impact Statement 

for tritium supply, taking stock worldwide nuclear deployments, 

locations of U.S. nuclear weapons by type, characterization and 

remediation of 91b radioactive waste site, radiological scoping and 

characterization survey report, 1963 Igloo 572 accident, appeal filed by 

Bowers, basewide operable unit draft preliminary assessment, San 

Antonio remembers, and an explosion that destroyed a weapon storage 

bunker. NOTE: 13 documents added by Site Association Review.

04/07/2012 30

Internet - Health Physics Journal No relevant documents identified. 04/10/2012 0

Internet - Journal of Occupational and Environmental 

Hygiene

No relevant documents identified. 04/10/2012 0

Internet - National Academies Press (NAP) No relevant documents identified. 04/02/2012 0

Internet - NIOSH Draft advisory board comments on site profile. 03/26/2012 1

Internet - NRC Agencywide Document Access and 

Management (ADAMS) 

Review of decommissioning plan, Eglin AFB, FL. 03/29/2012 1

Internet - USACE/FUSRAP (Corps Library) No relevant documents identified. 03/23/2012 0

Internet - USACE/FUSRAP (Ft. Worth District) No relevant documents identified. 03/26/2012 0
SEC-00203 05-31-12 Medina Modification Center 

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Table A1-1: Data Capture Synopsis for the Medina Modification Center

Data Capture Information General Description of Documents Captured Date 

Completed

Uploaded

To SRDB

Internet - USACE/FUSRAP (Headquarters) No relevant documents identified. 03/23/2012 0

Internet - USACE/FUSRAP (Southwest Division) No relevant documents identified. 03/26/2012 0

Internet - US Transuranium and Uranium Registries No relevant documents identified. 04/02/2012 0

Mound Museum Manufacturing statement for weapons production schedule of transfers. 07/14/2008 2

National Archives and Records Administration (NARA) -

College Park

[Name redacted] case. 07/15/2012 1

ORAU Team Dose records, contamination levels or limits, and a site profile. 02/09/2007 3

SAIC Summary of whole body exposures. 09/02/2004 2

Unknown Pantex Plant personnel dosimetry records, articles on nuclear weapons 

production processes and history, request for special quota - enriched 

uranium, and Rocky Flats site history.

08/19/2003 15

TOTAL 152

Table A1-2: Databases Searched for the Medina Modification Center

Database/Source Keywords / Phrases Hits Selected

NOTE: Database terms employed for each of the databases listed below are 

available in the Excel file called “Medina Facility Rev 00, (83.14) 04-20-12”

Defense Technical Information Center (DTIC)

https://www.dtic.mil/

COMPLETED 04/04/2012

See Note above 689 0

DOE CEDR

http://cedr.lbl.gov/

COMPLETED 04/10/2012

See Note above 0 0

DOE Hanford DDRS

http://www2.hanford.gov/declass/

COMPLETED 03/29/2012

See Note above 0 0

DOE Legacy Management Considered Sites

http://csd.lm.doe.gov/

COMPLETED 03/23/2012

See Note above 14 2
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Table A1-2: Databases Searched for the Medina Modification Center

Database/Source Keywords / Phrases Hits Selected

DOE NNSA - Nevada Site Office

www.nv.doe.gov/main/search.htm

COMPLETED 04/02/2012

See Note above 0 0

DOE OpenNet

http://www.osti.gov/opennet/advancedsearch.jsp

COMPLETED 03/29/2012

See Note above 64 30

DOE OSTI Energy Citations

http://www.osti.gov/energycitations/

COMPLETED 03/27/2012

See Note above 83 1

DOE OSTI Information Bridge

http://www.osti.gov/bridge/advancedsearch.jsp

COMPLETED 03/27/2012

See Note above 63 1

Google

http://www.google.com

COMPLETED 04/07/2012

See Note above 5,813,049 17

HP Journal

http://journals.lww.com/health-physics/pages/default.aspx

COMPLETED 04/10/2012

See Note above 1 0

Journal of Occupational and Environmental Health 

http://www.ijoeh.com/index.php/ijoeh

COMPLETED 04/10/2012

See Note above 1 0

National Academies Press

http://www.nap.edu/

COMPLETED 04/02/2012

See Note above 12,889 0

NRC ADAMS Reading Room

http://www.nrc.gov/reading-rm/adams/web-based.html

COMPLETED 03/29/2012

See Note above 30 1

USACE/FUSRAP (Corps Library)

http://www.corpslibrary.com/search/um/Browse.html

COMPLETED 03/23/2012

See Note above 0 0

USACE/FUSRAP (Ft. Worth District)

http://www.swf.usace.army.mil/

COMPLETED 03/26/2012

See Note above 22,770 0

USACE/FUSRAP (Headquarters)

http://www.usace.army.mil/Home.aspx

COMPLETED 03/23/2012

See Note above 8 0
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Table A1-2: Databases Searched for the Medina Modification Center

Database/Source Keywords / Phrases Hits Selected

USACE/FUSRAP (Southwestern Division)

http://www.swd.usace.army.mil/

COMPLETED 03/26/2012

See Note above 28,881 0

U.S. Transuranium & Uranium Registries 

http://www.ustur.wsu.edu/

COMPLETED 04/02/2012

See Note above 0 0

Table A1-3: OSTI Documents Requested for the Medina Modification Center

Document Number Document Title Requested

Date

Received

Date

No documents requested.