Clarksville Modification Center, 

Ft. Campbell

Special Exposure Cohort 

Petition Evaluation Report

Stuart L. Hinnefeld

Director

National Institute for Occupational Safety and Health

Division of Compensation Analysis and Support

June 2012

Santa Fe, NM
Petition Overview

 NIOSH determined it was not feasible to 

complete the dose reconstruction for an existing 

Clarksville Modification Center claim

 On May 23, 2012, claimant notified and 

provided with a copy of Special Exposure Cohort 

(SEC) Petition Form A

 May 24, 2012: Petition (83.14) submitted to 

NIOSH

 May 31, 2012: NIOSH Evaluation Report issued 
Background

 EEOICPA covered from 1949-1967 (DOE)

 Part of Ft. Campbell, occupying about 3.2 square 

miles of the base

 Located ~50 miles NW of Nashville on TN-KY 

border

 Constructed by AEC as a nuclear weapons 

storage area

 Jointly operated by AEC, Sandia Corp., and 

various branches of the military
Operations

 Site operational in August 1949

 Nuclear capsule storage in underground vault 

structures (A Structures)

 Weapons assembly, modification, and disassembly 

(B and C structures, gravel gertie)

 Activity checking of fissile material, replacing Po-Be 

initiators

 AEC transferred operations to Pantex in 1965, but 

some storage of classified materials continued until 

~1967

 Workforce—ranged from 118 in 1960 to a maximum 

of 230 in 1964
Clarksville Modification Center

B structure

C structure

A structure
Sources of Available Information

 ORAU Team Site Profiles and Technical 

Information Bulletins (TIBs) and Procedures

 NIOSH Site Research Database

 Existing claimant files

 Information from Pantex Plant SEC evaluation

 Worker interviews (4) as well as information 

from claimant telephone interview files (CATIs)

 Data captures
Data Capture Efforts

 DOE Opennet (OSTI data base)

 Standard data base search (DDRS, NNSA, CEDR etc.)

 Internet search

 Nuclear Regulatory Commission (ADAMS)

 Hanford/PNNL

 DOE Legacy Management

 State of Tennessee

 Various DOE locations, esp. Pantex

 Libraries (Clarksville county, Eastern KY University)
NOSH/OCAS Claims Tracking System 

(information as of May 21, 2012)

 Clarksville claims submitted to NIOSH 92

 Claims that meet the recommended class years 92

 Dose reconstructions completed for claims 70

 that meet the class definition 

 Claims containing some internal dosimetry 0

 Claims containing some external dosimetry 5
Potential Radiation Exposures

 Internal

• Airborne uranium oxides (HEU and DU)

• Tritium gases 

• Radon

• Plutonium

• Cs-137

 External

• Photon/beta and neutron exposures from

— Uranium

— Plutonium

— Polonium initiators

— Cs-137 from weapons components

— Ir-192 and Co-60 radiography sources
Personal Monitoring Data

 Internal monitoring data

• No indication that a routine bioassay monitoring 

program existed

• 5 urinalysis samples for DU for single worker (single 

incident )

 External monitoring data

• 1949-1960: dosimetry provided by Sandia (annual 

reports available)

• NTA film added in 1958 (results not available)

• 1960-1965: various dosimetry records and weekly 

summary data available (only some workers were 

monitored)
Work Place and Source Term Data

 Workplace monitoring

• Uranium contamination surveys during 1964 and 1965

• Some indication that tritium air monitoring and 

swipes took place, records have not been located

• No records of routine radon air monitoring

 Source-term monitoring

• Radioactive materials consisted of tritium, HEU, DU, 

plutonium, radon, Po-210, radiography sources

• Insufficient information is available on the source 

terms of these materials
Feasibility of Dose Reconstructions

 Available internal monitoring records, process 

descriptions, and source-term data are 

inadequate to complete dose reconstructions 

with sufficient accuracy for the evaluated class 

of employees during the period from August 1, 

1949 through December 31, 1967

 The findings from this SEC evaluation are 

consistent with the SEC determinations for 

facilities with similar radiological exposures:

• Pantex Plant 

• Medina Modification Center
Feasibility of Dose Reconstructions—cont. 

 External doses can be reconstructed using 

available external monitoring data and available 

dose reconstruction methods:

• Available film badge data likely from highest exposed 

worker group

• Neutron doses are assigned using neutron-to-photon 

ratios of similar operations

• Doses from X-ray examinations are assigned based on 

available methodology
Feasibility Summary

Feasibility Findings for Clarksville Modification Center

Dose Dose Reconstruction 

Source of Exposure Reconstruction 

Feasible

NOT Feasible

Internal

X 

External

 - Beta-Gamma X 

 - Neutron X 

 - Occupational X 

Medical X-ray
Health Endangerment

 The evidence reviewed in this evaluation 

indicates that some workers in the class may 

have accumulated chronic radiation exposures 

through intakes of radionuclides and direct 

exposure to radioactive materials.

 Consequently, NIOSH is specifying 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 .
Proposed Class

All employees of the Department of Energy, its 

predecessor agencies, and DOE contractors or 

subcontractors who worked at the Clarksville 

Modification Center, Ft. Campbell in Clarksville, 

Tennessee during the period from August 1, 1949 

through December 31, 1967, 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.
Recommendation

 For the period from January 1, 1949 through 

December 31, 1967, NIOSH finds that radiation 

dose estimates cannot be reconstructed for 

compensation purposes

Class Feasibility Health Endangerment

January 1, 1949 –

December 31, 1967 No Yes