ORAU TEAM

Dose Reconstruction

Project for NIOSH

Oak Ridge Associated Universities I Dade Moeller & Associates I MJW Corporation

Page 1 of 91

Document Title:

Hanford Site – Occupational External 

Dose

Document Number: ORAUT-TKBS-0006-6 

Revision: 02

Effective Date: 11/21/2006

Type of Document: TBD

Supersedes: Revision 01

Subject Expert: Edward D. Scalsky

Approval: Signature on File Approval Date: 11/06/2006

Edward D. Scalsky, Document Owner

Approval: Signature on File Approval Date: 11/09/2006

John M. Byrne, Task 3 Manager

Concurrence: Signature on File Concurrence Date: 11/07/2006

Edward F. Maher, Task 5 Manager

Concurrence: Signature on File Concurrence Date: 11/15/2006

Kate Kimpan, Project Director

Approval: Brant A. Ulsh Signature on File for Approval Date: 11/21/2006

James W. Neton, Associate Director for Science

 New Total Rewrite Revision Page Change

FOR DOCUMENTS MARKED AS A TOTAL REWRITE, REVISION, OR PAGE CHANGE, REPLACE THE PRIOR 

REVISION AND DISCARD / DESTROY ALL COPIES OF THE PRIOR REVISION.
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 2 of 91

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION 

NUMBER DESCRIPTION

10/10/2003 00 First approved issue. Initiated by Edward D. Scalsky.

01/09/2004 01 Approved Issue of Revision 01. Initiated by Edward D. Scalsky.

10/05/2006 01 PC-1 Approved page change revision to add updated required language 

on page 8 in Section 6.1. Adds Purpose Section (6.1.1) and Scope 

Section (6.1.2) to page 9. Makes reference to ORAUT-OTIB-0017 

on page 10 in Section 6.2 for guidance to be used. Adds two 

references to pages 56 and 58 in Reference Section. No changes 

occurred as a result formal internal review. Incorporates NIOSH 

formal review comments. This revision results in no change to the 

assigned dose and no PER is required, Training required: As 

determined by the Task Manager. Initiated by Edward D. Scalsky.

Approval: 

Edward D. Scalsky, Document Owner

Signature on File_________________ _____________09/02/2006

John M. Byrne, Task 3 Manager

Signature on File_________________ _____________09/05/2006

Signature on File_____________________ ________________

Edward F. Maher, Task 5 Manager

09/29/2006

Signature on File_______ _______________________ Kate Kimpan, Project Director10/03/2006

Brant A. Ulsh Signature on File for ___ _____________ James W. Neton, Associate Director for Science10/05/2006

11/21/2006 02 Approved Revision 02 to incorporate SC& A comments and 

responses to claimant concerns. Constitutes a total rewrite of 

document. Incorporates internal and NIOSH formal review 

comments. This revision results in no change to the assigned dose 

and no PER is required. Training required: As determined by the 

Task Manager. Initiated by Edward D. Scalsky.
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 3 of 91

TABLE OF CONTENTS

SECTION TITLE PAGE

Acronyms and Abbreviations ............................................................................................................... 7

6.1 Introduction ..............................................................................................................................9

6.1.1 Purpose...................................................................................................................10

6.1.2 Scope ......................................................................................................................10

6.2 External Dosimetry................................................................................................................. 10

6.3 Basis of Comparison..............................................................................................................11

6.4 Dose Reconstruction Parameters........................................................................................... 11

6.4.1 Hanford Historical Administrative Practices ............................................................. 12

6.4.2 Incidents.................................................................................................................. 14

6.4.3 Hanford Dosimetry Technology................................................................................ 15

6.4.3.1 Beta/Photon Dosimeters......................................................................... 16

6.4.3.2 Neutron Dosimeters ............................................................................... 18

6.4.4 Calibration ............................................................................................................... 19

6.4.4.1 Hanford Beta/Photon Dosimeters ........................................................... 19

6.4.4.2 Hanford Neutron Dosimeters.................................................................. 22

6.4.5 Workplace Radiation Fields ..................................................................................... 23

6.4.5.1 Hanford Beta/Photon Dosimeter Response Testing ............................... 23

6.4.5.2 Hanford Workplace Beta/Photon Dosimeter Response .......................... 27

6.4.5.3 Uncertainty in Beta/Photon Recorded Dose ........................................... 29

6.4.5.4 Hanford Neutron Dosimeter Response Testing ...................................... 33

6.4.5.5 Hanford Workplace Neutron Dosimeter Response ................................. 36

6.4.5.6 Neutron to Photon Ratio......................................................................... 42

6.4.5.7 Neutron Dose Fraction ........................................................................... 47

6.4.5.8 Uncertainty in Neutron Dose .................................................................. 49

6.5 Adjustments to Recorded Neutron Dose ................................................................................ 49

6.5.1 Neutron Dose Adjustments...................................................................................... 49

6.5.2 Neutron Weighting Factor........................................................................................ 49

6.5.3 Neutron Correction Factor ....................................................................................... 50

6.6 Missed Dose ..........................................................................................................................51

6.6.1 Photon Missed Dose................................................................................................ 51

6.6.1.1 Year ....................................................................................................... 51

6.6.2 Neutron Missed Dose .............................................................................................. 52

6.6.2.1 Year ....................................................................................................... 53

6.6.2.2 Facility/Location...................................................................................... 53

6.6.2.3 Dosimeter Type...................................................................................... 53

6.6.2.4 Energy Range ........................................................................................ 53

6.7 Uncertainty.............................................................................................................................54

6.7.1 Missed Dose............................................................................................................ 54

6.7.2 Positive Recorded Photon Dose .............................................................................. 55

6.7.3 Neutron Dose .......................................................................................................... 56
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6.8 Analysis of Claims Filed by Hanford Workers......................................................................... 57

6.8.1 Years with a Claim................................................................................................... 57

6.8.2 Analysis of Assigned Doses..................................................................................... 58

6.9 Recommendations for HANFORD Worker External Dose Reconstruction.............................. 59

6.9.1 Adjustments to recorded occupational dose ............................................................ 59

6.9.2 Determination of Missed External Dose for Low-Dose Results for Monitored 

 Workers...................................................................................................................60

6.9.3 Determination of Missed Neutron Dose for Monitored and Unmonitored Workers ... 60

6.9.4 Adjustment for Glovebox Workers ........................................................................... 61

6.9.5 Unmonitored Worker External Dose ........................................................................ 61

6.9.6 Skin Dose................................................................................................................ 61

6.9.7 Extremity Dose ........................................................................................................ 62

6.9.8 Radiation Dose Fraction .......................................................................................... 62

6.9.9 Organ Dose .............................................................................................................62

6.9.10 Claim Analysis Methods .......................................................................................... 63

6.9.10.1 Minimizing Assumptions......................................................................... 63

6.9.10.2 Maximizing Assumptions........................................................................ 63

6.9.10.3 Best Estimate Assumptions.................................................................... 63

6.10 Uncertainty in Photon and Neutron Doses ............................................................................. 63

References........................................................................................................................................ 64

Glossary............................................................................................................................................ 71

ATTACHMENT A,OCCUPATIONAL EXTERNAL DOSE FOR MONITORED WORKERS................. 80

A.0 Distribution Parameters.......................................................................................................... 81

A.1 Years of Exposure..................................................................................................................81

A.2 Rate .......................................................................................................................................81

A.3 Radiation Type.......................................................................................................................81

A.3.1 Beta/Photon.............................................................................................................81

A.3.2 Neutron....................................................................................................................83

A.4 Distribution Parameters.......................................................................................................... 84

A.4.1 Type ........................................................................................................................84

A.4.2 Parameter 1.............................................................................................................84

A.4.2.1 Resolution of Recorded Dose Components............................................ 84

A.4.2.2 Adjustments to Recorded Penetrating Dose........................................... 85

A.4.2.3 Adjustments to Recorded Neutron Dose ................................................ 86

A.4.2.4 Unmonitored Photon Dose ..................................................................... 88

A.4.2.5 Missed Photon Dose .............................................................................. 88

A.4.2.6 Missed Neutron Dose............................................................................. 89

A.4.2.7 Organ Dose............................................................................................ 91

A.4.3 Parameter 2.............................................................................................................91

A.4.3.1 Hanford Workplace Recorded Dose Uncertainty .................................... 91
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LIST OF TABLES

TABLE TITLE PAGE

6-1 Hanford historical dosimetry events .......................................................................................15

6-2 Laboratory sources of uncertainty for beta/photon dosimeter calibration 

parameters.............................................................................................................................20

6-3 Analysis of two-element film dosimeter dose..........................................................................21

6-4 Laboratory sources of uncertainty for neutron dosimeter calibration parameters....................22

6-5 IARC testing results for U.S. beta/photon dosimeters.............................................................24

6-6 Testing results for Hanford two-element and multielement film dosimeters for 

energy and angular response................................................................................................. 24

6-7 Workplace measured nonpenetrating and penetrating collective doses ................................. 25

6-8 Analysis of multielement film dosimeter dose.........................................................................27

6-9 Hanford workplace photon spectra measurements................................................................. 28

6-10 Hanford workplace photon dosimeter Hp(10) performance .....................................................30

6-11 Uncertainty in beta/photon Hp(10) in Hanford facilities............................................................31

6-12 Overall bias and uncertainty due to variation and uncertainties regarding energy 

levels and geometry in recorded dose as an estimate of deep dose ......................................32

6-13 Selection of beta and photon radiation energies and percentages for Hanford 

facilities ..................................................................................................................................32

6-14 Parallel workplace measured NTA and HMPD neutron dose .................................................34

6-15 Recording periods for selected Hanford plutonium workers....................................................35

6-16 Ratio of recorded Hanford dose components .........................................................................35

6-17 Hanford workplace neutron spectra measurements ...............................................................37

6-18 Estimated neutron and photon dose rates for Hanford reactor front face................................38

6-19 200 Area workplace measurement comparisons with HMPD .................................................41

6-20 Neutron/photon ratios for reactor workers identified in PNNL-11196. .....................................43

6-21 Ratio of neutron to photon dose for graphite moderated reactor.............................................44

6-22 Hanford neutron to photon dose ratios ...................................................................................46

6-23 Laboratory-measured dose fractions from PuF4 .....................................................................47

6-24 200 Area measured dose fractions.........................................................................................48

6-25 300 Area measured dose fractions.........................................................................................48

6-26 400 Area measured dose fractions.........................................................................................48

6-27 Uncertainty in neutron Hp(10) in Hanford facilities ..................................................................49

6-28 Historical neutron quality or weighting factors ........................................................................50

6-29 Hanford Facility dose fractions and associated ICRP 60 correction factors ............................51

6-30 Hanford photon dosimeter period of use, type, MDL, exchange frequency, and 

potential annual missed dose................................................................................................. 52

6-31 Hanford neutron dosimeter period of use, type, MDL, exchange frequency, and 

potential annual missed dose................................................................................................. 52

6-32 Overall estimates of uncertainty for photon dose in Hanford non-plutonium 

facilities ..................................................................................................................................55

6-33 Estimate of Overall Photon and Neutron Radiation Bias Factor..............................................56

6-34 Frequency of claims according to duration of Hanford employment .......................................57

6-35 Potential missed dose for low-dose values.............................................................................60

6-36 Potential neutron dose ...........................................................................................................61

6-37 Historical Hanford recorded dose practices............................................................................61

A-1 IREP dose parameter input screen ........................................................................................81

A-2 Selection of beta and photon radiation energies and percentages .........................................82
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A-3 Hanford facility neutron radiation energies, percentages, and default neutron 

dose fractions International Commission on Radiological Protection (ICRP) 60 

correction factors ...................................................................................................................84

A-4 Historical Hanford recorded dose practices............................................................................86

A-5 Hanford neutron-to-photon dose ratios...................................................................................87

A-6 Missed photon dose adjustments to recorded deep dose.......................................................88

A-7 Hanford neutron dosimeter period of use, type, MDL, exchange frequency, and 

potential annual missed dose................................................................................................. 89

A-8 Hanford Facility dose fractions and associated ICRP 60 correction factors ............................90

LIST OF FIGURES

FIGURE TITLE PAGE

6-1 Trend in the collective dose for Hanford workers and the number of monitored 

Hanford workers, 1944-1989..................................................................................................14

6-2 Trend in the number of Hanford monitored workers, the number of workers with 

recorded photon > 0, the number of workers with recorded neutron dose > 0, and 

the total collective dose, 1944-1989 .......................................................................................14

6-3 Measured Hanford dosimeter photon response characteristics ..............................................21

6-4 Comparison of Hanford film and TLD penetrating dose results...............................................26

6-5 Comparison of Hanford film and TLD nonpenetrating dose results.........................................26

6-6 Ratio of nonpenetrating (NPEN) to penetrating (PEN) dose for HMPD and film 

parallel workplace measurements ..........................................................................................29

6-7 Comparison of Hanford PFP workplace NTA and HMPD neutron dose..................................34

6-8 Ratio of annual Hanford collective neutron dose to plutonium production...............................35

6-9 Neutron spectra for Hanford 400 Area FFTF..........................................................................39

6-10 Degradation in neutron energy spectra for bare, 2.54 cm and 5.08 cm of acrylic 

plastic shielding with neutron energy groups overlay..............................................................41

6-11 Neutron energy spectra recorded at Hanford PFP 234-5Z “C” line, glovebox, and 

plutonium storage vault ..........................................................................................................41

6-12 Neutron spectra for Hanford 308 and 324 facilities................................................................. 42

6-13 Lognormal plot of Table 6-22 data..........................................................................................43

6-14 Adjusted neutron/photon ratio for Hanford reactors................................................................44

6-15 Neutron/photon dose ratio distribution of Hanford plutonium facility workers..........................45

6-16 Lognormal distribution of data in Figure 6-15 .........................................................................46

6-17 Annual dose components for a single Hanford worker, 1948-1976.........................................54

6-18 Frequency distribution of archive records for active Hanford claims within the 

respective years.....................................................................................................................58

6-19 Comparison of average and maximum annual measured penetrating dose as 

originally recorded in Buschbom and Gilbert (1992) and as assigned in dose 

reconstruction prior to inclusion of missed occupational (external and internal 

radiation), medical X-ray, or ambient assigned dose..............................................................59
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ACRONYMS AND ABBREVIATIONS

AP anterior-posterior (X-ray)

AEC U.S. Atomic Energy Commission

CP Cutie Pie (measurements) 

DCF dose-rate conversion factors

DE dose equivalent

DOE U.S. Department of Energy

DOELAP DOE Laboratory Accreditation Program

DOL U.S. Department of Labor

EE Energy Employee

EEOICPA Energy Employees Occupational Illness Compensation Program Act

FFTF Fast Flux Test Facility

GM geometric mean

HEW Hanford Engineering Works

HMPD Hanford Multipurpose TLD

Hp(d) Personal Dose Equivalent at depth d in tissue

IARC International Agency for Research on Cancer

ICRP International Committee for Radiological Protection

ICRU International Commission on Radiation Units and Measurements

IREP Interactive RadioEpidemiological Program

ISO International Standards Organization

MED Manhattan Engineer District

MDL Minimum Detection Level

mm millimeter

NBS National Bureau of Standards (predecessor to NIST)

NCRP National Council on Radiation Protection and Measurements

NIOSH National Institute for Occupational Safety and Health

NIST National Institute of Standards and Technology 

NPEN (Hanford) designation of nonpenetrating dose

NRC National Research Council

NTA Eastman-Kodak Nuclear Track, Type A emulsion

ORNL Oak Ridge National Laboratory

OW (Hanford) designation of open window (i.e., no filter) nonpenetrating dose

PEN (Hanford) designation of penetrating dose

PFP Plutonium Finishing Plant

PFPP Plutonium Fuels Pilot Plant 

PIC Pocket Ionization Chamber (i.e., “Pencil” dosimeter)

PNNL Pacific Northwest National Laboratory

POC probability of causation
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PRTR Plutonium Recycle Test Reactor Facility

PUREX Plutonium-Uranium Extraction Plant

R Roentgen

RBE Relative Biological Effectiveness

REDOX Reduction Oxidation Plant

rem radiation equivalent man

RMA remote mechanical A (line) series of glove boxes

RMC remotely operated series of glove boxes

S (Hanford) designation of penetrating dose behind 1 mm thick silver filter

SRS Savannah River Site

TBD technical basis documents

TED track-etch dosimetry 

TEPC Tissue Equivalent Proportional Counter

TLD thermoluminescent dosimeter

WB whole-body
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6.1 INTRODUCTION

Technical basis documents and site profile documents are not official determinations made by 

the National Institute for Occupational Safety and Health (NIOSH) but are rather general 

working documents that provide historic background information and guidance to assist in the 

preparation of dose reconstructions for particular sites or categories of sites. They will be 

revised in the event additional relevant information is obtained about the affected site(s). 

These documents may be used to assist NIOSH staff in the completion of the individual work 

required for each dose reconstruction.

In this document, the word “facility” is used as a general term for an area, building, or group of 

buildings that served a specific purpose at a site. It does not necessarily connote an “atomic 

weapons employer facility” or a “Department of Energy [DOE] facility” as defined in the Energy 

Employees Occupational Illness Compensation Program Act [EEOICPA; 42 U.S.C. § 7384l(5) 

and (12)]. EEOICPA defines a DOE facility as “any building, structure, or premise, including 

the grounds upon which such building, structure, or premise is located ... in which operations 

are, or have been, conducted by, or on behalf of, the Department of Energy (except for 

buildings, structures, premises, grounds, or operations ... pertaining to the Naval Nuclear 

Propulsion Program)” [42 U.S.C. § 7384l(12)]. Accordingly, except for the exclusion for the 

Naval Nuclear Propulsion Program noted above, any facility that performs or performed DOE 

operations of any nature whatsoever is a DOE facility encompassed by EEOICPA.

For employees of DOE or its contractors with cancer, the DOE facility definition only 

determines eligibility for a dose reconstruction, which is a prerequisite to a compensation 

decision (except for members of the Special Exposure Cohort). The compensation decision for 

cancer claimants is based on a section of the statute entitled “Exposure in the Performance of 

Duty.” That provision [42 U.S.C. § 7384n(b)] says that an individual with cancer “shall be 

determined to have sustained that cancer in the performance of duty for purposes of the 

compensation program if, and only if, the cancer ... was at least as likely as not related to 

employment at the facility [where the employee worked], as determined in accordance with the 

POC [probability of causation1

As noted above, the statute includes a definition of a DOE facility that excludes “buildings, 

structures, premises, grounds, or operations covered by Executive Order No. 12344, dated 

February 1, 1982 (42 U.S.C. 7158 note), pertaining to the Naval Nuclear Propulsion Program” 

[42 U.S.C. § 7384l(12)]. While this definition contains an exclusion with respect to the Naval 

Nuclear Propulsion Program, the section of EEOICPA that deals with the compensation 

decision for covered employees with cancer [i.e., 42 U.S.C. § 7384n(b), entitled “Exposure in 

the Performance of Duty”] does not contain such an exclusion. Therefore, the statute requires 

NIOSH to include all occupationally derived radiation exposures at covered facilities in its dose 

reconstructions for employees at DOE facilities, including radiation exposures related to the 

Naval Nuclear Propulsion Program. As a result, all internal and external dosimetry monitoring 

results are considered valid for use in dose reconstruction. No efforts are made to determine 

the eligibility of any fraction of total measured exposure for inclusion in dose reconstruction. 

NIOSH, however, does not consider the following exposures to be occupationally derived:

] guidelines established under subsection (c) ... ” [42 U.S.C. § 

7384n(b)]. Neither the statute nor the probability of causation guidelines (nor the dose 

reconstruction regulation) define “performance of duty” for DOE employees with a covered 

cancer or restrict the “duty” to nuclear weapons work.

 

1 The U.S. Department of Labor is ultimately responsible under the EEOICPA for determining the POC. 
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• Radiation from naturally occurring radon present in conventional structures

• Radiation from diagnostic X-rays received in the treatment of work-related injuries

6.1.1

Hanford

Purpose

was established in 1942 as a major government-owned nuclear weapons production site 

fabricating reactor fuel, eventually operating nine nuclear material production reactors and building 

five major chemical separation plants, and producing plutonium for nuclear weapons. Later 

operations included nonmilitary applications of nuclear energy. The purpose of this TBD is to 

describe the external dosimetry systems and practices at Hanford. This document discusses 

historical and current practices in relation to the evaluation of external radiation exposure of monitored 

and unmonitored workers. 

6.1.2

Hanford played a crucial historical role in the U.S. nuclear weapons program producing plutonium for 

nuclear weapons and generating two-thirds of all nuclear waste, by volume, in the DOE complex 

(Gerber 1992). Certainly, the war-time operations at Hanford Engineering Works (HEW) were 

characterized by secrecy and the sheer magnitude of building the first-ever industrial-sized nuclear 

reactors, reprocessing, and plutonium handling facilities. Today, the Hanford Site houses large 

quantities of nuclear waste and is engaged in an extensive waste remediation project. 

Scope

The methods and concepts of measuring occupational external doses to workers have evolved since 

the beginning of Hanford operations. An objective of this document is to provide a technical basis to 

evaluate external radiation exposure to workers that can reasonably be associated with Hanford

operations under EEOICPA legislation. Consistent with NIOSH guidelines, this document identifies 

options to adjust historical recorded occupational external dose to account for current scientific 

methods and protection factors. In particular, this document presents the methods to prepare worker 

dose information for input to the NIOSH Interactive RadioEpidemiological Program (IREP). 

6.2 EXTERNAL DOSIMETRY 

Hanford operations involved several processes of the nuclear weapons development cycle (DOE 

2002, 1997, 1996) and played a significant role in the U.S. nuclear weapons program. These 

processes include nuclear fuel fabrication; nuclear reactor operations; radiochemical separations; 

refining, finishing and storing plutonium; and handling the associated radioactive waste. 

Hanford workers, especially those employed during the peak production decades of the 1950s and 

1960s, have been exposed to radiation types and energies associated with the respective nuclear 

weapon development processes. Hanford utilized facility and individual worker monitoring methods to 

measure and control radiation exposures. Many Hanford records concern facility monitoring, safety 

evaluations, investigations, etc. Evaluations after many years or even decades after employment are 

difficult because of the extensive scope of facility, process, and worker information relevant to an 

individual worker’s potential dose. Records of radiation doses to individual workers from personnel 

dosimeters worn by the worker and coworkers are available for Hanford operations beginning in 1944

(Buschbom and Gilbert 1993) and reviews of the Hanford personnel dose data for 10- and 15-year 

periods from Hanford startup in Parker (1954) and Keene (1960), respectively. Doses from these 

dosimeters were recorded at the time of measurement and routinely reviewed by Hanford operations 

and radiation safety staff for compliance with radiation control limits. The NIOSH External Dosimetry 

Implementation Guide (NIOSH 2002) has identified these records to represent the highest quality 

records for retrospective dose assessments. The information in this section pertains to analyzing 
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these records and does not address parameters regarding skin, testicular, or breast radiation dose 

that could result from acute beta (electron) radiation exposure under short-term accidental or incident 

nonroutine workplace exposure profiles. Nonpenetrating radiation during routine operations is also 

not addressed in this section. Guidance in ORAUT-OTIB-0017 (ORAUT 2005a) should be used to 

assess shallow dose for Hanford claimants. 

Radiation dosimetry practices were initially based on experience gained during several decades of 

radium and X-ray medical diagnostic and therapy applications. These methods were generally well 

advanced at the start of the Manhattan Engineer District (MED) program to develop nuclear weapons

beginning in about 1940. The primary new challenges encountered by MED, and later Atomic Energy 

Commission (AEC), operations to measure worker dose to external radiation involved:

• 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.

6.3 BASIS OF COMPARISON 

Historically, since the start of the MED program in the early 1940s, various radiation dose concepts

and quantities have been used to measure and record occupational dose. A basis of comparison for 

dose reconstruction (Fix et al. 1997a) is the Personal Dose Equivalent, Hp(d), where d identifies the 

depth (in millimeters) and represents the point of reference for dose in tissue. For weakly penetrating 

radiation of significance to skin dose, d = 0.07 mm and is noted as Hp(0.07). For penetrating radiation 

of significance to “whole-body” dose, d = 10 mm and is noted as Hp(10). Both Hp(0.07) and Hp(10) are 

the radiation quantities recommended for use as the operational quantity to be recorded for 

radiological protection purposes by the International Commission on Radiation Units and 

Measurements (ICRU 1993). In addition, Hp(0.07) and Hp(10) are the radiation quantities used in the 

DOE Laboratory Accreditation Program (DOELAP), which has been used to accredit DOE personnel 

dosimetry systems since the mid-1980s (DOE 1986). The International Agency for Research on 

Cancer (IARC) Three Country Combined Study (Fix et al. 1997a) and IARC Collaborative Study 

(Thierry-Chef et al. 2002) selected Hp(10) as the quantity to use for assessing error in recorded wholebody doses for workers in IARC nuclear worker epidemiologic studies. 

The basis for comparison for neutron radiation is more complicated because historically, the 

calibration of dosimeters to measure neutron dose was based on different dose quantities such as 

First Collision Dose, Multiple Collision Dose, Dose Equivalent Index, etc. The numerical significance 

in using these dose quantities compared to the Hp(10) dose used in current DOELAP performance 

testing represents an additional uncertainty in retrospective dose analyses. The relative value of the 

dose conversion factors for the respective neutron dose quantities used at Hanford has not been 

compared because, as noted in later sections, the response characteristics of the Eastman Kodak 

Nuclear Track Film Type A (NTA) was not adequate in Hanford workplace radiation fields.

6.4 DOSE RECONSTRUCTION PARAMETERS

Examinations of the beta, photon (X-ray, gamma ray), and neutron radiation type, energy, and 

geometry of exposure in the workplace and the characteristics of the respective Hanford dosimeter 

response are crucial to the assessment of bias and uncertainty of the original recorded dose in 

relation to the radiation quantity Hp(10). The bias and uncertainty for current Hanford dosimetry 

systems are well documented for Hp(10) (Rathbone 2002). The performance of current dosimeters 
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can often be compared with performance characteristics of historical dosimetry systems in the same, 

or highly similar, facilities or workplaces. In addition, current performance testing techniques can be 

applied to earlier dosimetry systems to achieve a consistent evaluation of historical dosimetry 

systems. Dosimeter response characteristics for radiation types and energies in the workplace are 

crucial to the overall analysis of error in recorded dose.

Overall, accuracy and precision of the original recorded individual worker doses and their 

comparability to be considered in using NIOSH (2002) guidelines depend on (Fix et al. 1997a):

• Administrative practices adopted by facilities to calculate and record personnel dose based 

on technical, administrative, and statutory compliance considerations.

• Dosimetry technology, which includes the physical capabilities of the dosimetry system, such 

as the response to different types and energies of radiation, in particular in mixed radiation 

fields.

• Calibration of the respective monitoring systems and similarity of the methods of calibration to 

sources of exposure in the workplace.

• Workplace radiation fields that might include mixed types of radiation, variations in exposure 

geometries, and environmental conditions.

An evaluation of the original recorded doses based on these parameters is expected to provide the 

best estimate of Hp(10) and, as necessary, Hp(0.07) for individual workers with the least relative 

overall uncertainty. 

6.4.1

Historically, Hanford had an extensive radiation safety monitoring program to measure exposure in 

the workplace using portable radiation instruments (Howell et al. 1989), contamination surveys, zone 

controls, and personnel dosimeters (Parker 1954; Wilson 1987). This was done directly or under the 

guidance of a specially trained group of radiation monitors (i.e., radiation protection technologists). 

The results from the personnel dosimeters were used to measure and record dose from external 

radiation exposure to Hanford workers throughout the history of Hanford operations (Wilson 1987). 

These dosimeters, as noted in the Health Instrument section of routine reports (Miller 1946; Parker 

1948), include one or more of the following:

Hanford Historical Administrative Practices

• Personnel whole-body (WB) beta/photon dosimeters 

• Pocket Ionization Chamber (PIC) dosimeters 

• Personnel extremity dosimeters

• Personnel whole-body neutron dosimeters

Hanford began operations in 1944 using in-house dosimeter and processing technical support. 

Hanford based its beta/photon film dosimetry methods on the dosimeter design developed at the 

Metallurgical Laboratory by Pardue, Goldstein, and Wollan (1944). This design was implemented at 

several of the MED sites. Hanford implemented its individual worker neutron dosimetry methods 

beginning in 1944 using PICs with a 10B-enriched lining. In 1950, the NTA emulsion dosimeter

capability was implemented. 

Parameters concerning Hanford administrative practices significant to dose reconstruction include:

• Policies to assign dosimeters to workers (Parker 1955). 
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• Policies to exchange dosimeters. 

• Policies to record the measured dose and not using a notional dose (i.e., some identified value 

for lower dosed workers often based on a small fraction of the regulatory limit). 

• Policies to estimate dose for missing or damaged dosimeters. 

• Policies to replace destroyed or missing records. 

• Policies to evaluate and record dose for incidents. 

• Policies to obtain and record occupational dose to workers for other employer exposure. 

Hanford policies appear to have been in place for all of these parameters (Parker 1948). Routine 

Hanford practices appear to have required assigning dosimeters to all workers who entered a 

controlled radiation area (Hart 1967). Dosimeters were exchanged on a routine schedule. All 

dosimeters were processed and the measured results were recorded and used to estimate dose. 

There appears to be no use of recorded notional doses, although there are issues of “missed” 

recorded dose for low-dosed dosimeters (see section on “missed dose”) as well as recorded doses for 

individual dosimeters at levels less than the statistical Minimum Detection Level (MDL). 

Early Hanford dosimetry procedures (HEW 1946) describe several aspects of the routine dosimetry 

program. Hanford workers entering operating areas were assigned dosimeters beginning in 1944. 

Trends in the number of monitored workers and the collective dose for these workers are shown in 

Figures 6-1 and 6-2. These figures illustrate the number of workers with positive recorded dose from 

photon and neutron radiation, respectively, along with the number of monitored workers. The trends 

in the respective Figures do not show any abrupt changes that may be indicative of significant 

changes in photon dosimetry or assignment of dosimeters (Buschbom and Gilbert 1993). Figure 6-2 

does illustrate abrupt changes in the number of workers with neutron dose greater than zero. This is 

discussed later in this section. 

Administrative practices are generally described in Wilson (1987). A description of the content of the 

historical recorded dose values for each year by Fix, Carbaugh, and MacLellan (2001) and detailed 

information for each worker is in the NIOSH claim documentation. The claim documentation provides 

specific information to be evaluated regarding the recorded dose of record. There does not appear to 

be any significant administrative practice that would jeopardize the integrity of the recorded dose of 

record. Gilbert (1990) found agreement between the original paper records and computerized dose 

records. In addition, evaluations of Hanford film dosimeter results were examined in the 1960s at the 

University of Pittsburgh as part of the AEC Health and Mortality Study of Hanford workers (AEC 

1966). The evaluation by University of Pittsburgh researchers was that the recorded dose data 

showed that “good quality control was exercised over the film badge calibration and processing 

procedures at Hanford over the years (i.e., 1944-61).”
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 14 of 91

1.E+03

1.E+04

1.E+05

1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990

Year

No. of Monitored Workers

Collective Dose (person-rem) for All Workers

 Figure 6-1. Trend in the collective dose for Hanford workers and the number 

 of monitored Hanford workers, 1944-1989. 

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990

Year

No. of Monitored Workers

No. of workers, Recorded Annual Dose > 0

No. of workers, Recorded Neutron Dose > 0

 Figure 6-2. Trend in the number of Hanford monitored workers, the number

 of workers with recorded photon > 0, the number of workers with recorded 

 neutron dose > 0, and the total collective dose, 1944-1989. 

6.4.2

External radiation dose from worker involvement in incidents is included in the dose of record for 

Hanford workers. There have been significant incidents during the history of Hanford. A few primary 

incidents are described below: 

Incidents

P-11: The purpose of the P-11 facility was to test critical safe geometries to assist with design of the 

fuel reprocessing systems and systems at the 234-5 Plutonium Finishing plant. The P-11 processes 

were purposely operated near the edge of criticality to determine operational bounds. These bounds 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 15 of 91

were exceeded resulting in a fire during 1950 in the atmospheric exhaust filter systems (Leonard 

1952). 

Recuplex: A criticality accident occurred on April 7, 1962, in a plutonium waste chemical recovery 

facility called Recuplex associated with the 234-5 building. Twenty-four workers were involved, 

including two patrolmen stationed at the entry gatehouse. Photon doses to workers were measured 

with personnel dosimeters. Neutron doses were determined from whole body counts and blood 

activation measurements along with measurements of 32P in hair and radioactivity in objects that were 

on the workers as well as threshold detectors and recording instruments in the building. The highest 

exposed worker received 23-30 rad from fast neutrons and 63 R to the central part of the body. This 

person also received about 42-54 rad from the fast neutron radiation to his eyes (Gamertsfelder et al. 

1962). 

241Am Explosion: In 1976, a chemical explosion occurred at Hanford resulting in a nuclear chemical 

operator being extensively contaminated and receiving an intake of 241Am by skin absorption and 

inhalation (see Hanford Site Profile Chapter 5). 

N-Reactor: On December 16, 1977, an irradiated fuel discharge occurred exposing four workmen on 

an elevator resulting in personnel radiation exposures in excess of radiation safety limits. The 

incident was identified as a Class B occurrence (according to DOE Manual Chapter 0502) and an 

investigation committee formed to oversee the process of determination of cause for the accident and 

the process of dose reconstruction (United Nuclear Industries 1977). 

6.4.3

Hanford external dosimetry practices are essentially the same as practices adopted at the MED 

Metallurgical (now University of Chicago) and Clinton (now Oak Ridge National Laboratory [ORNL]) 

laboratories in the early to mid-1940s. Parker (1945) described results of intercomparisons of 

dosimeter processing and exposure calculations between these three laboratories prior to declaring 

the Hanford system capable of routine dosimeter processing. Comparisons of dose interpretation 

among these MED/AEC sites and other sites were done through the years (Wilson 1960a, Wilson et 

al. 1990). All of these sites followed a similar evolution in dosimetry technology using PICs in addition 

to a two-element film dosimeter in the 1940s and early 1950s, leading to multielement film dosimeters 

in the later 1950s, followed by thermoluminescent dosimeters (TLDs) in the 1960s and 1970s. The 

adequacy of the respective dosimetry methods to measure radiation dose accurately is determined 

from the radiation type, energy, exposure geometry, etc., as described in later sections. The 

dosimeter exchange frequency was gradually lengthened, generally corresponding to the period of the 

regulatory dose controls (GE 1954). At the beginning of Hanford operations, a dose control of 1 mSv 

per day (100 millirem/day) was in effect. This was changed to a dose control of 3 mSv per week (300 

millirem/week) and later to a limit of 50 mSv per year (5,000 millirem) in the later 1950s. Table 6-1 

summarizes major operational events in the Hanford personnel dosimetry program. 

Hanford Dosimetry Technology

Table 6-1. Hanford historical dosimetry events (Wilson 1987, Wilson et al. 1990).

Date Description

1/1944 PICs used for a few months to measure dose for each worker prior to film dosimeter 

availability. Thereafter, PICs used in addition to film dosimeters. 

10/1944 Two-element (i.e., open window and 1-mm silver filter) beta/photon film dosimeter issued to 

personnel. Film response under the silver filter was converted to personnel dose by 

comparing film optical density response with calibrated film response from 226Ra. Minimum 

detectable dose based on laboratory irradiations was 0.3 mSv (30 millirem) (Wilson 1960b).

Routine dosimeter exchange period was weekly. 

1/1948 Beta/photon dosimeter exchange changed to biweekly.

1/1950 NTA was issued to personnel to measure neutron dose. Film exchange was weekly.
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Uranium used to calibrate open window beta response.

Extremity film dosimeter use and processing began.

1952 Identified penetrating dose calculation as OW/5 + S, likely only in plutonium facilities, but 

actual practice not verified. As such, in this TBD, it is assumed that this was not done.

4/1957 Multielement film dosimeter use was implemented. This design permitted analysis of beta, 

gamma, and X-ray exposure to personnel. 

5/1957 Monthly beta/photon film dosimeter exchange implemented.

7/1957 New dosimeter holder implemented exclusively for NTA film.

1958 Automated densitometer and computer analysis capability introduced to replace manually 

operated densitometer. 

7/1958 NTA exchange changed to bi-weekly.

1962 Second multielement film dosimeter design implemented; replaced design used since 1957. 

This dosimeter incorporated nuclear accident capabilities in addition to routine personnel 

dosimetry. 

1963 Quarterly film dosimeter exchange for nonradiological workers implemented.

3/1964 Tritium dose included in annual whole-body dose. 

1966 Accumulated dose from 1944-1961 was rounded up to nearest multiple of 10 millirem (i.e., 

2,487 to 2,490). Thereafter, all doses shown to nearest multiple of 10 millirem.

late 1960s Parallel field testing of new TLDs and film dosimeter conducted. Selected Hanford workers 

wore both dosimeters. 

1/1971 Basic (one-chip) TLD implemented.

1/1972 Five-chip Hanford Multipurpose TLD (HMPD) implemented.

7/1978 Four-chip HMPD implemented.

1/1984 Five-chip HMPD reinstated.

Mid-1980s On-phantom calibration of dosimeters implemented to conform to preliminary DOELAP 

performance testing criteria. Laboratory testing showed 8% and 4% increase, respectively, 

in dosimeter response for on-phantom exposure using 226Ra or 137Cs exposures. 

1/1/1987 Routine photon calibration changed to 137Cs from 226Ra source. Overall change in recorded 

dose, described in Fix et al. (1982), was a 7% decrease from previous methods because of 

the decrease resulting from on-phantom calibration (-10%) and increase in recorded dose 

from the dose conversion factor (+3%).

1989 Hanford TLD is DOELAP-accredited for performance testing. Lower limit of detection, 

based on DOELAP protocol for laboratory irradiations, was about 0.2 mSv (20 millirem) for 

deep dose components. 

1/1/1995 Commercial Harshaw dosimetry system replaced Hanford site-specific TLD. Routine 

dosimeter exchange is quarterly and monthly.

6.4.3.1 Beta/Photon Dosimeters

The following paragraphs describe the Hanford beta/photon dosimeters and period of routine use to 

provide the recorded dose of record.

Pocket Ionization Chamber, 1944. During January 1944, before the Hanford film dosimetry system 

was operational, PICs were used for a few months to provide the dose of record (Wilson 1987). PICs 

were issued to employees in duplicate (i.e., two to each worker) and exposures were recorded daily. 

PICs consist of an electrically charged chamber that indicates radiation exposure as the charge 

decreases. The decrease in charge occurs from radiation exposure (i.e., ionization) but may also 

occur from any cause that reduces charge such as humidity, physical impact, etc. As such, PICs 

typically over-estimate the exposure from routine handling and environmental effects (Watson 1957). 

Because of “false-positive” dose from routine handling and environmental effects, the lower of the two 

readings for each day was used to calculate the dose for comparison with the daily dose limits at that 

time. Following use as the earliest dosimeters, PICs have been used throughout the history of 

Hanford operations to provide administrative control of worker dose until the dosimeter being worn 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 17 of 91

was processed and the dose calculated. It has been routine practice since at least the early 1950s to 

compare the doses measured with PICs and dosimeters and, for significant differences, to document 

the reason(s) for the discrepancy.

Two-Element Film Dosimeter, October 1944 to March 1957. The same design as that used at the 

Clinton Laboratory (now ORNL) and later by other MED/AEC/DOE laboratories. The Hanford design 

consisted of an open window and a 1-mm silver shield. Records of dosimeter film processing identify 

the regions of the dosimeter film as “OW” for open window and “S” for shielded. A calibration factor 

for each batch of film was used to convert measured optical density to dose. The optical density and 

the interpreted dose are included in the original Hanford dosimetry forms. Hanford implemented a 

two-element beta/photon dosimeter in 1944 based on the design developed by Pardue, Goldstein, 

and Wollan (1944) at the Metallurgical Laboratories. In 1952, the practice was begun to include 20% 

of the OW dose to the S dose to calculate the penetrating dose in plutonium facilities (Fix, Wilson, and 

Baumgartner 1997). However, this practice has not been verified with the actual dosimeter 

processing results and recorded doses. 

Another feature of the Hanford beta/photon film dosimeter was the use of 502-type film with a 

sensitive (lower radiation dose response) and an insensitive (typically accident-level dose response) 

side to each film packet. Normally, only the sensitive side of the film was useful for personnel dose

assessment. However, Hanford individual worker personnel dose forms included space to record the 

insensitive film response. Prior to 1957, the processing data were recorded manually. Worker 

personnel dose forms were updated each year to enable staff to record dosimeter results directly for 

each dosimeter exchange period and each operating area. These forms were organized to enable 

manual entry of dosimeter results and to record the total annual and cumulative dose for each worker. 

In 1958 (approximately), annual dose data were transferred to the newly implemented Hanford 

radiological computer database. During entry of the older records, a dose recorded prior to 1958 as a 

multiple of 5 millirem (i.e., 0, 5, 10,15, etc.) was rounded up to the first multiple of 10 millirem (i.e., 15 

millirem became 20, etc.). This provided consistency with the new (computer-based) practice of 

recording dose only to the first multiple of 10 millirem (10, 20, 30, etc.). This practice is still in use.

Multielement Film Dosimeters, April 1957 to December 1971. Hanford used multielement film 

dosimeters to measure beta, X-ray, and gamma radiation dose components in one of two designs 

during the periods of 1958 to 1961 and 1962 to 1971, respectively. These “beta/photon” film

dosimeters consisted of four shielded areas and provided a substantially improved capability to 

measure Hp(0.07) and Hp(10). Processing results (i.e., optical density) were recorded for the film 

response behind each filter and an algorithm was used to calculate the respective dose components. 

Thirty-five percent of the X-ray dose was assigned to the whole-body dose of record based on depth 

dose measurements in water at Hanford for 16 keV k-fluorescent X-ray (Wilson et al. 1990). Water 

closely simulates the radiation response of tissue. The whole-body dose also included the assigned 

neutron dose, as described in this chapter, and beginning in March 1964, the assigned tritium dose 

based on methods described in Chapter 5 along with other nuclide intake into the body. The tritium 

dose was recorded separately after 1987. The skin dose of record was calculated as the sum of the 

whole-body (i.e., penetrating, 35% of X-ray, neutron, and tritium) and nonpenetrating doses. 

Thermoluminescent Dosimeter, January 1972 to December 1994. Hanford has used TLDs in a 

few configurations. A “Basic” TLD (Kathren 1970) with limited capability for beta and photon (X- and 

gamma ray) radiation was used from January 1, 1971, through about 1988. This dosimeter, which 

had one chip, was assigned to personnel with little or no potential to receive dose (Wilson 1987). 

Hanford Multipurpose TLDs (HMPDs) were used from January 1, 1972, through December 31, 1994, 

to measure beta, photon, and neutron radiation. HMPDs originally had a five-chip design, which was 

changed to a four-chip design in July 1977 (Glenn 1977) to enable use of a commercial reader system 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 18 of 91

and then, returned to a five-chip design in January 1983 (Fleischman 1982) until the system was 

replaced on January 1, 1995, with a commercial system. The same filtration was used in the HMPD 

through all the years of use. These dosimeters were assigned to personnel likely to work in radiation 

fields. The HMPD was first accredited for performance testing in 1989 by the DOELAP in beta, 

photon and neutron radiation categories. The system has been reaccredited during later (typically 2-

year) accreditation cycles. 

Commercial TLD System, January 1995–Present. Hanford implemented a commercial Harshaw 

TLD system on January 1, 1995. This system includes a four-chip beta/photon dosimeter and a 

separate neutron dosimeter. Technical characteristics are described in the Hanford External 

Dosimetry Technical Basis Manual (Rathbone 2002).

6.4.3.2 Neutron Dosimeters 

Hanford has used three general types of neutron dosimeters, which differ substantially in their 

response to neutron radiation (Brackenbush et al. 1980). 

• Pocket Ionization Chamber. Prior to 1950, Hanford relied on PICs with enriched 10B liners to 

detect slow neutron exposure (Wilson 1987).

• Neutron Track Emulsion. The Hanford NTA neutron dosimeter was implemented on January 

1, 1950, and used through December 31, 1971. 

• Thermoluminescent Dosimeter. The HMPD for beta, photon, and neutron radiation was 

implemented on January 1, 1972. The HMPD was implemented as a 5-chip design with an 

automated reader system (Kocher et al. 1971). Hanford implemented a commercial Harshaw 

TLD system on January 1, 1995. 

The following paragraphs describe the Hanford personnel neutron dosimeters and their periods of use 

(Fix, Wilson, and Baumgartner 1997). 

Pocket Ionization Chamber, Prior to 1950. Enriched 10B liners were used in PICs to detect slow 

neutron exposure (Wilson 1987). This method is generally acceptable to detect the presence of slow 

neutrons but not for dose measurement. There is no recorded neutron dose for any Hanford worker 

prior to 1950 (Buschbom and Gilbert 1993). 

NTA Film, January 1950 to December 1971. Hanford NTA film, which was introduced on January 1, 

1950, was processed independently from the beta/photon film even though the NTA film was typically 

exchanged along with the beta/photon film. Prior to 1957, NTA film was housed in the two-element 

beta/photon dosimeter holder along with the beta/photon film. Beginning in 1958, the NTA film was 

housed in an NTA-specific holder assigned to personnel. There was space in the yearly forms 

manually prepared before 1957 to record the neutron dose. The Hanford policy to process NTA film 

varied historically but basically involved the practice to read all NTA film for the 200 West plutonium 

facilities and, for other Hanford facilities, to process the NTA only if the photon dose was at least 100 

mrem. This was based on the observation (Watson 1959) that neutron dose was always 

accompanied by photon dose. For the other facilities, potential neutron dose was considered to be 

relatively small compared to the photon dose. A neutron dose is recorded for all Hanford workers 

assigned an NTA film. If it was not processed, a zero neutron dose is recorded. The earliest 

recorded neutron dose for Hanford workers occurred in 1950 (Buschbom and Gilbert 1993). 

Five-Chip HMPD, January 1972 to June 1977. The five-chip HMPD incorporated a neutron dose 

capability that involved three of the five chips (i.e., 3, 4, and 5). The combination of these chips 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 19 of 91

provided capabilities to estimate thermal (i.e., slow) and fast neutron components with the capability 

(chip 5) for an accurate beta/photon response correction (i.e., neutron-sensitive chips also respond to 

photon and high-energy beta radiation) (Kocher et al. 1971). Effective July 1, 1977, the dose 

algorithm was changed to use data for only four of the chips (i.e., not chip 5) to utilize the four-chip 

cards that were being implemented (Wilson et al. 1990). 

Four-Chip HMPD, July 1977 to December 1983. The HMPD dosimeter was modified to a four-chip 

design to accommodate introduction of a commercial reader system in the later 1970s that required 

the dosimeter cards to pivot around the center where chip 5 was located. Tens of thousands of 

HMPD cards were fabricated with chip 5 removed. These modified cards were used in the original 

five-chip holders. 

Five-Chip HMPD, January 1984 to December 1994. Routine dose evaluation with the five-chip 

HMPD was returned to service effective on January 1, 1984. Several refinements were made to this 

system (Wilson et al. 1990) to prepare for DOELAP performance testing. The HMPD was first 

accredited by DOELAP for performance testing in neutron categories in 1989 and reaccredited every 

subsequent (typically 2-year) accreditation cycle thereafter. 

Commercial TLD System, January 1995 to Present. Hanford implemented a commercial Harshaw 

TLD system beginning on January 1, 1995. The neutron dosimeter system was originally a 

combination TLD and track-etch dosimetry (TED) system but essentially the TLD capability was used 

for all routine dose evaluations. Routine use of the TED capability has been discontinued since it did 

not accurately measure worker dose in the workplace (Scherpelz et al. 2000). 

6.4.4

Potential error in recorded dose is dependent on the dosimetry technology response characteristics to 

each radiation type, energy, and geometry; the methodology used to calibrate the dosimetry system; 

and the similarity between the radiation fields used for calibration and the fields in the workplace. 

Early evaluations of Hanford workplace radiation fields were performed such as for uranium by 

McAdams (1949a), plutonium surface dose (Roesch 1957; Keene 1957), and neutron instruments by 

McAdams (1949b, 1950). The potential error is much greater for dosimeters with significant variations 

in response, such as the film dosimeters to low-energy photon radiation and the NTA and HMPD 

response to neutron radiation. 

Calibration

6.4.4.1 Hanford Beta/Photon Dosimeters

Hanford dosimeters were originally calibrated using 226Ra gamma, uranium beta, and 80 keV X-rays 

(HEW 1946). Routine irradiation in air (i.e., no phantom) of calibration film was done for each batch of 

film. This included 10 exposure levels from 100 to 30,000 mR to 226Ra gamma radiation, seven 

exposure levels from 100 to 5,000 mrads to uranium beta radiation, and 100 to 1,000 mR from 80 keV 

X-ray radiation (HEW 1946). Calibration films were processed with all personnel dosimeters. In the 

early 1950s, Hanford k-fluorescent X-ray capabilities were used to develop dosimeter response 

characteristics for the lower energy photon fields in plutonium facilities (Wilson 1987; Fix, Gilbert, and 

Baumgartner 1994; Wilson et al. 1990). Studies by Fix et al. (1982,1981) describe technical 

characteristics of Hanford recorded dose compared to the Hp(10) dose based on work performed for 

Hanford’s participation in the DOELAP performance testing that was formally required in the latter 

1980s (DOE 1986). At that time, it was concluded that a 10% decrease in the recorded dose would 

result from on-phantom calibration irradiations. This effect is partially compensated by the 3% 

increase in recorded dose resulting from use of the 137Cs dose to exposure conversion factor (Fix et 

al. 1982, Study 2).
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 20 of 91

No change in the recorded dose is proposed to account for the approximate 7% over-estimate in the 

recorded dose prior to the implementation of on-phantom calibration or other similar comparatively 

small changes because of the overall uncertainty of changes made over the years. Table C.2 of 

Wilson et al. (1990) lists a chronology of changes to the Hanford TLD system. Common sources of 

laboratory bias are listed in Table 6-2 for personnel beta/photon dosimeter calibration based on 

comparison of the recorded dose with Hp(10). Wilson (1960b) measured a standard deviation of 

±25% (one-sigma) based on laboratory irradiations performed to estimate the dosimetry detection 

level (i.e., about 30 mrem). 

Figure 6-3 shows the laboratory measured anterior-posterior (AP) photon energy response of the 

respective Hanford dosimeter systems. As noted in this figure, the film dosimeter OW response 

shows a significant over-response to lower energy photon radiation. Operationally, the over-response 

was so significant that some option was necessary to interpret the dosimeter response based on the 

anticipated radiation fields in the work environment. The ratio of the OW to the filtered film response 

was routinely used in dose evaluation (Larson and Roesch 1954) and there is reference to using a 

fraction (0.2) of the OW response to add to the penetrating dose in facilities with low-energy photons 

and no beta radiation (i.e., plutonium facilities) (Fix, Wilson, and Baumgartner 1997). However, it has 

not been validated that this was actually done. An analysis of the bias in the nonpenetrating and 

penetrating dose is presented in Table 6-3. The Hanford recorded skin dose is calculated as the sum 

of the OW and S filtered film response. The recorded Hanford whole body (WB) dose is calculated 

using 20% of the OW film response in addition to the measured S film response using the historical 

Hanford dosimeter testing data in Appendix A of Wilson et al. (1990). As noted in this table, the 

calculated WB dose for the lower energy photons characteristic of Hanford plutonium facilities is 

conservatively estimated using this practice in comparison with Hp(10). The practice is applicable only 

to workers in Hanford plutonium facilities. Application of this practice to Hanford reactor and 

radiochemical facilities with primarily mixed beta and photon fields would result in a significant 

overestimate of Hp(10) as noted in Table 6-3 for uranium and 90Sr/90Y exposures. As such, a 

recommendation that is favorable to claimants for plutonium workers only, is to apply the calculation 

of the WB dose using 20% of the OW dose in addition to the measured S dose pending confirmation 

that the historical Hanford WB dose does indeed include the 20% of the OW dose. 

Table 6-2. Laboratory sources of uncertainty for beta/photon dosimeter calibration parameters. 

Parameter Historical description Uncertaintya Comment

In-air calibration In the 1980s, Hanford began 

exposing calibration 

dosimeters on phantoms 

(used to simulate worker 

body). Previous calibrations 

do not include response from 

radiation backscatter 

response.

+10% Recorded dose of record too high. 

Backscatter radiation from worker body 

is highly dependent on dosimeter 

design. Fix et al. (1982, Study 2) 

measured a bias of about 10% for 

137Cs gamma radiation with HMPD.

Radiation quantity Before 1980s, Hanford 

dosimeter systems were 

typically calibrated to a photon 

beam measured as exposure. 

-5% For higher energy 226Ra and 137Cs 

gamma radiation used to calibrate 

dosimeters, this caused a slight (about 

3%) under-response in recorded 

dose. 

Tissue depth

of dose

Historically, Hanford used an 

unspecified depth to estimate 

the deep dose. 

±5% The numerical effect of this for photon 

radiation is comparatively low. Hanford 

dosimeter designs had filtration density 

thickness of about 1,000 mg/cm2 that 

would relate closely to the 1-cm depth 

in tissue. 

Angular response Hanford dosimeter system is 

calibrated using AP laboratory 

> 300 keV, 

~20%

Recorded dose of record likely too low 

since the dosimeter response is usually 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 21 of 91

irradiations. lower at non-AP angles. Effect is 

highly dependent on radiation type and 

energy. 

Environmental 

stability

Hanford film dosimeter and 

TLD systems are subject to 

signal fade with time, heat, 

humidity, light, etc.

±10% Recorded dose of record depends 

strongly on dosimetry parameters, 

such as when calibration dosimeters 

were irradiated and processed. Midcycle calibration minimizes effects. 

a. Uncertainty estimate in recorded dose compared to Hp(10) based on Hanford dosimeter laboratory studies. 

0.1

1

10

100

0.01 0.1 1 10

R

e

l

a

t

i

v

e

R

e

s

p

o

n

s

e

Energy, MeV

Hp(10)

Film OW

Silver Shield

Multi-Element Dosimeter Dose

TLD Dose

137Cs

 Figure 6-3. Measured Hanford dosimeter photon response characteristics (Wilson et 

 al. 1990).

Table 6-3. Analysis of two-element film dosimeter dose.a

Source

Exposure

(mR)b

Delivered dose, mremc Dosimeter dose Recorded dosed

Hp(0.07) Hp(10) OW S Skin WB

16 keV 40 43 15 353 7 360 78

80 86 30 710 7 717 149

160 173 61 2213 3 2216 446

59 keV 30 44 46 653 17 670 148

50 74 77 1237 23 1260 270

80 118 123 2553 27 2580 538

137Cs 50 52 52 7 50 57 51

240 247 247 10 247 257 249

750 773 773 24 750 774 755

1000 1030 1030 47 1000 1047 1009

Uranium 50 50 0 50 0 50 10

240 240 0 250 0 250 50

750 750 0 756 20 776 171

1000 1000 0 1000 23 1023 223

90Sr/90Ye 50 50 0 103 3 106 24

240 240 0 353 3 356 74

750 750 0 1370 13 1383 287

1000 1000 0 2070 6 2076 420

a. PNL-7447, Appendix A, dosimeter data, average value shown in table.

b. Photon dose in mR and beta dose in mrad.

c. Exposure to dose conversion factors from DOELAP Standard (DOE 1986).

d. Skin Dose = OW + S, WB dose = S + 0.2 * OW.

e. Table shows factor of about 2 over-response to 90Sr/90Y based on uranium calibration.
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 22 of 91

6.4.4.2 Hanford Neutron Dosimeters

Historical aspects of Hanford neutron fields, NTA dosimeters, and calibration are described in Roesch 

(1951, 1954), Swanberg (1959) and Wilson (1960b, 1960c) and an historical evaluation of Hanford 

NTA and HMPDs described by Fix, Wilson, and Baumgartner (1997). Table 6-4 lists common 

sources of laboratory bias for personnel neutron dosimeter calibration based on the expected 

comparison of the recorded dose with Hp(10). Brackenbush et al. (1980) describes the energy 

response characteristics of NTA and TLD dosimeters, and these are characteristic of Hanford neutron 

dosimeters. Fundamentally, the NTA dosimeter is capable of an accurate dose estimate for higher 

energy neutron radiation greater than about 1 MeV because the NTA has a lower energy threshold of 

about 700 keV. 

The Hanford TLD (Kocher et al. 1971) has a comparatively high response to thermal neutrons and is 

generally used to measure neutron radiation scattered from the workers body (i.e., the Albedo effect). 

The NTA and TLD neutron dosimeters must be calibrated to neutron spectra similar to that present in 

the workplace for accurate dose results. There are many Hanford reports on technical aspects of 

neutron source calibration (Fix et al. 1997b). Several address the controversy concerning whether a 

first-collision or multiple-collision neutron dose factor should be used. A significant change based on 

Hanford studies (Budd 1963) showed no significant statistical difference in response between NTA 

dosimeters exposed to PuBe and PuF4 neutron source irradiations in-air and on-phantom. Based on 

this, the identified action was to change to the multiple-collision Relative Biological Effectiveness 

(RBE) dose from a single collision RBE dose effective with the 2-week period ending July 12, 1963. 

The difference in recorded dose between the two calibration references was an increase in recorded 

neutron dose of about 35%. 

Table 6-4. Laboratory sources of uncertainty for neutron dosimeter calibration parameters. 

Parameter Historical description Uncertaintya Comment

Source 

energy

spectra

Hanford has used many sources to 

calibrate dosimeters (Fix, Wilson, and 

Baumgartner 1997) and perhaps in 

calibration geometries to degrade the 

spectra such as with the PuF4 source. 

±100% The delivered dose used in 

calibrating neutron dosimeters, 

particularly the NTA, is uncertain

as noted in Fix, Wilson, and 

Baumgartner (1997) (see workplace 

radiation fields).

Radiation 

quantity

Neutron dose quantities used to 

calibrate neutron dosimeter systems 

have varied historically; these 

quantities primarily include first and 

multiple collision dose, and neutron 

dose equivalent index factors.

±50% This represents a significant and 

complicated issue, particularly for 

early neutron sources. 

Angular

response

Hanford dosimeters calibrated using 

AP laboratory irradiations.

-50% Recorded dose of record likely too 

low because dosimeter response is 

often lower at angles other than AP. 

Effect is highly dependent on 

energy. 

Environmental

stability

NTA film dosimeter and TLD systems 

are subject to signal fade with time, 

heat, humidity, light, etc.

±50% Recorded dose of record likely too 

low because of fading; however, 

this effect depends strongly on such 

routine dosimetry practices as when 

calibration dosimeters were 

irradiated. 

a. Uncertainty in recorded dose compared to Hp(10) based on laboratory studies.
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 23 of 91

6.4.5

Hanford operations are characterized by significant complex beta, photon, and neutron radiation fields 

in Hanford reactor, irradiated fuel processing, plutonium handling, and radioactive waste facilities. 

Workplace Radiation Fields

6.4.5.1 Hanford Beta/Photon Dosimeter Response Testing

In 1944, when the Hanford two-element dosimeter was being implemented, an intercomparison test 

was performed with the Metallurgical and Clinton laboratories to evaluate the respective dosimetry 

systems, which were essentially identical (Parker 1945). This testing led to the following conclusions: 

• The badge systems at all three sites were satisfactory for adequate determination of gamma 

radiation exposure of personnel.

• The calibrations of all three laboratories were in agreement.

• More frequent calibrations at high exposures should be made.

• Greater attention to photometer reproducibility is desirable.

The evaluation also concluded that greater attention to beta and low-energy X-rays was needed at 

Hanford and that neutron films (i.e., NTA) are useful only for higher neutron exposures than will 

normally occur at Hanford. These statements were made in 1945 prior to operation of many of the 

Hanford facilities. Later, it became evident that mixed beta/photon radiation fields and neutron 

radiation presented a significant technical challenge, which led to ongoing research and development 

in Hanford dosimetry technology.

Several studies of Hanford film dosimeter performance, stability of latent image, etc., were performed 

during the 1950s (Wilson 1957a, 1957b, 1960a, 1960b, 1960c). As described in Wilson et al. (1990), 

many intercomparison and performance studies were done at Hanford and between Hanford and 

other MED/AEC/DOE facilities. These studies generally confirmed the acceptability of Hanford 

assessment of nonpenetrating and penetrating dose as defined at that time. Several studies of the 

HMPD were performed (Fix et al. 1981, 1982) in preparing for the DOELAP performance testing that 

included explicit identification of dose quantities (ANSI 1983, DOE 1986) as measured in comparison 

to what is now referred to as the Personal Dose Equivalent, Hp(d), were d refers to a 0.07- or 10-mm 

depth in tissue. In general, only small changes (± 10%) were necessary to improve comparison in 

laboratory studies with Hp(10), although additional changes were necessary to improve overall 

precision (Fix et al. 1982, Wilson et al. 1990). 

In recent years, further studies of early dosimeter performance compared to Hp(10) have been made 

because of its use in worker health effect studies. The IARC conducted a dosimeter intercomparison 

study to higher energy (i.e., >100 keV) photons of 10 commonly used dosimetry systems used 

throughout the world (Thierry-Chef et al. 2002). Two of the film dosimeter designs were from Hanford: 

(1) the two-element dosimeter design (identified as US-2) and (2) the multielement film dosimeter 

design (identified as US-8). The IARC Study considered that exposure to dosimeters worn by 

workers could be characterized as AP, rotational and isotropic irradiation geometries, or a 

combination thereof. Dosimeter response to selected photon energies was measured using two 

phantoms, which were used to simulate the effect of the worker’s body on the measured dosimeter 

response. The first phantom was the International Standards Organization (ISO) water-filled slab 

phantom, which is used for dosimeter calibration and performance testing. The second was an 

anthropomorphic Alderson Rando Phantom, which is constructed from a natural human skeleton cast 

material that has a tissue equivalent response. The results of IARC testing (for U.S. dosimeters only) 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 24 of 91

are listed in Table 6-5. This table includes results for the DOE Savannah River Site (SRS) 

commercial TLD (US-22) that also participated in IARC testing. SRS dosimeter performance is 

expected to be representative of the Hanford TLD system.

 Table 6-5. IARC testing results for U.S. beta/photon dosimeters. 

Geometry Phantom

118 keV 208 keV 662 keV

Meana SD/Mean Meana SD/Mean Meana SD/ Mean

US-2 (Hanford two-element film dosimeter)

AP Slab 3.0 2.1 1.3 1 1.0 0.8

AP Anthropomorphic 3.0 4.2 1.2 1.9 1.0 1.8

Rotational Anthropomorphic 2.2 2 1.4 3 1.2 3.2

Isotropic Anthropomorphic 1.5 4.4 1.1 1.6 1.0 2.7

US-8 (Hanford multielement film dosimeter)

AP Slab 1.0 1.5 1.0 0.8 0.8 1.7

AP Anthropomorphic 0.8 9.5 0.9 6 0.8 1.8

Rotational Anthropomorphic 1.2 1.9 1.2 17 1.1 1.8

Isotropic Anthropomorphic 1.0 3 1.2 9 1.0 2.3

US-22 (SRS multi-element thermoluminescent dosimeter)

AP Slab 0.9 4.4 0.9 3.9 0.9 3.5

AP Anthropomorphic 0.8 3.1 0.9 2.1 0.9 3.9

Rotational Anthropomorphic 1.1 3.1 1.2 1.5 1.0 4.1

Isotropic Anthropomorphic 0.9 0.3 1.0 2.5 0.9 1.6

a. Ratio of recorded dose to Hp(10). 

Hanford conducted intercomparison testing of all its historical film dosimeter designs using AP (Wilson 

et al. 1990) and angular (Fix et al. 1994) irradiations on an Alderson Rando phantom essentially 

identical to the phantom used in the IARC studies. These studies included lower-energy (i.e., < 100 

keV) photons that are significant in Hanford plutonium facilities. Data from Fix et al. (1994) and 

Wilson et al. (1990) are summarized in Table 6-6. The dosimeter results for energies greater than 

100 keV are consistent with the IARC results, showing an over-estimate of Hp(10) for the two-element 

dosimeter. 

Table 6-6. Testing results for Hanford two-element and multielement film dosimeters for energy and 

angular response.

a,b

Beam

(energy, 

keV)

AP exposure Rotational exposure

Film dosimeters TLD

1972–

present

Film dosimeters

TLD

1972–93

Two-element

1944–56

Multielement

1957–71

Two-element 

1944–56

Multielement

1957–71

16c 0.1 0.9

59c 0.27 1.1

M150(70) 0.7 0.70 0.95 1.31 1.31 1.77

H150(120) 1.6 0.64 0.87 3.00 1.20 1.64

137Cs(662) 1.0 1.0 1.0 1.46 1.46 1.46

a. Divide recorded dose by table value to estimate Hp(10). 

b. Based on Fix et al. (1994)

c. Based on Wilson et al. (1990).

For energies less than 100 keV, the two-element dosimeter will underestimate the photon dose 

without using some method of adjustment such as a fraction of the dosimeter OW or silver shielded 

response. This potential under-response is evident in the original University of Chicago two-element 

dosimeter energy response curve (Pardue, Goldstein, and Wollan 1944). 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 25 of 91

Another source of data to evaluate relative performance is presented in Nichols et al. (1972), in which 

data were collected from parallel field testing in 1970 and 1971 of the Hanford multielement film 

dosimeter and the HMPD that was implemented on January 1, 1972. Measurements were performed

(some involving dosimeters placed on water-filled carboys) at 49 work locations in the PlutoniumUranium Extraction Facility (PUREX), B-Plant, Plutonium Finishing Plant (PFP), 105-KE Building 

(reactor operating), 100-N (reactor not operating), and the 325-B, 325, and 327 Buildings. Table 6-7 

lists the collective nonpenetrating and penetrating dose measured with the Hanford film dosimeter and 

HMPD and, when available, the open window (nonpenetrating) and closed window (penetrating) 

ionization chamber “Cutie Pie (CP)” measurements. This table includes measurements with selected 

calibration sources. The information in Table 6-7 generally shows acceptable agreement considering 

the variability in the field measurements are similar to those of the calibration sources. The 

nonpenetrating response of the film dosimeter was routinely calibrated with a uranium slab source, 

whereas a 90Sr/90Y source was routinely used to calibrate the HMPD nonpenetrating response. There 

is an approximate factor of 2 difference in dosimeter response between these two sources and this is 

shown in this table (i.e., for 90Sr/90Y source irradiation, 690 mrem for film versus 315 mrem for TLD). 

Table 6-7. Workplace measured nonpenetrating and penetrating collective doses (Nichols et al. 1972).

Facility

Nonpenetrating, mrad Penetrating, millirem

Film TLD CP Film TLD CP

Purex 4,260 3,790 3,640 3,480 3,570 2,806

B-Plant 10,550 9,510 13,850 2,250 4,560 4,920

PFP 4,060 4,220 (np) 3,920 4,090 5,410

105-KEa 9,390 9,150 10,324 9,390 9,100 10,104

105-Nb 12,070 13,440 7,880 12,030 13,050 7,350

325-B 1,100 1,250 (np) 1,100 1,250 1,760

325 3,690 5,710 5,100 2,640 2,850 3,220

327 870 1,090 (np) 870 1,090 2,260

Calibration sources

Ra-226 260 310 (np) 260 310 300

PuF4 60 100 (np) 60 100 (np)

90Sr/90Yc 690 315 (np) 0 100 275

252Cf 135 180 (np) 135 180 (np)

np – not provided in Nichols et al. (1972).

a. Plant operating.

b. Plant not operating

c. Film calibrated with uranium slab. TLD is calculated with 90Sr/90Y. There is about a factor of 2 difference; results 

in this table illustrate this.

The report by Nichols et al. (1972) described another aspect of these field studies that involved 150 

personnel wearing beta/photon film dosimeters and HMPDs simultaneously during November 1970 

and January 1971. Figures 6-4 and 6-5 present the comparison of the penetrating and 

nonpenetrating dose, respectively, for Hanford workers from several facilities including the PFP, which 

is the most likely workplace environment of potential problems. The photon spectrum at PFP does 

have a significant lower-energy component that is comparatively more difficult to measure and is likely 

to have varied historically. Significant fission product contamination of the plutonium is likely to have 

occurred in the beginning of Hanford operations. 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 26 of 91

0

1

2

3

4

5

6

7

8

9

10

0 1 2 3 4 5 6 7 8 9 10

TLD, rem

Film, rem

 Figure 6-4. Comparison of Hanford film and TLD penetrating dose results (Nichols et 

 al. 1972).

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5

TLD, rad

Film, rad

 Figure 6-5. Comparison of Hanford film and TLD nonpenetrating dose results (Nichols 

 et al. 1972).

During later years, there is significant ingrowth of 241Am, and its 60-keV gamma radiation is often 

dominant (Roberson, Cummings, and Fix 1985; Fix 1988). It is apparent from Figure 6-4 that the 

penetrating dose compares reasonably well between the Hanford multielement film and the HMPD for 

all facilities although there appears from this data a potential bias in multi-element film. Analysis of 

the potential bias in multi-element film dosimeter results relative to the TLD results in the field test by 

Nichols et al. (1972) is difficult because of the many uncertainties concerning workers’ practices to 

wear and position the dosimeters. Dosimeter nonpenetrating and penetrating response 

characteristics depend upon many parameters including the radiation type, energy and directional 

parameters as well as the worker orientation in the workplace. The collective dose for each of the 

facilities in which workers wore multi-element film dosimeters and TLDs is presented in Table 6-7. 

The variability in workplace measurements in Table 6-7 is similar to the variability in the calibration 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 27 of 91

source measurements using the three methods of measurement, each of which has different radiation 

type, energy, and geometry response characteristics. 

A wide range of mixed beta and photon radiation and energies is characteristic of these facilities. The 

most significant difference in penetrating dose occurred at the B-Plant. This is likely associated with 

the relatively high nonpenetrating radiation dose indicative of beta and lower-energy photons and the 

penetrating dose response of the HMPD to higher energy beta radiation as noted in Fix et al. (1982) 

and Wilson et al. (1990). The HMPD records a penetrating dose for higher energy beta radiation such 

as 90Sr/90Y, when there should be none, because there is only 380 mg/cm2 density thickness in the 

aluminum filter over the HMPD chip used to calculate the deep dose.

The performance of the multi-element film dosimeter compared to Hp(0.07) and Hp(10) was analyzed 

using the multi-element dosimeter results in Appendix A of PNL-7447. The results are presented in 

Table 6-8. This information provides good evidence that the multielement film dosimeter reasonably 

estimates Hp(10) and Hp(0.07).

A report by Fix, Gilbert, and Baumgartner (1994) describes laboratory measurements of Hanford film 

and thermoluminescent dosimeter angular response characteristics used to estimate the bias and 

uncertainty in recorded Hanford Dose using methods developed by the National Research Council 

(1989) based on considerations of bias and uncertainty in radiological, environmental, and radiation 

field parameters. The report identifies biases and uncertainties in personnel dosimeter results for 

photon energies greater than 100 keV. Bias factors were found to primarily depend upon the photon 

radiation energy, the geometry, and the dosimetry system. Bias factors presented in this report are 

consistent with the IARC and Wilson et al. (1990) results presented in Tables 6-5 and 6-6, 

respectively. Additional discussion of results in this report is described under uncertainty in workplace 

beta/photon dose.

 Table 6-8. Analysis of multielement film dosimeter dosea

Source

Exposur

e (mR)b

Delivered dose, 

mremc Dosimeter dose Recorded dosed

Hp(0.07) Hp(10) Beta X-ray Gamma Skin WB

16 keV 40 43 15 0 40 0 40 14

80 86 30 16 78 7 101 34

160 173 61 106 160 0 266 56

59 keV 30 44 46 0 64 24 88 46

50 74 77 0 126 37 163 81

80 118 123 0 216 50 266 126

137Cs 50 52 52 0 0 50 50 50

240 247 247 0 0 240 240 240

750 773 773 0 0 726 726 726

1,000 1,030 1,030 0 0 993 993 993

90Sr/90Y 50 50 0 74 0 0 74 0

240 240 0 302 4 0 306 1

750 750 0 1,000 16 0 1,016 6

1,000 1,000 0 1,340 18 0 1,358 6

a. PNL-7447, Appendix A, dosimeter data, average value shown in table.

b. Photon dose in mR and beta dose in mrad.

c. Exposure to dose conversion factors from DOELAP Standard (DOE 1986).

d. Skin dose = Beta + X-ray + Gamma. Whole Body (WB) = gamma + 0.35 * beta

6.4.5.2 Hanford Workplace Beta/Photon Dosimeter Response

Field measurements of photon radiation spectra and dose have been performed on many occasions. 

Table 6-9 is a summary of several of those measurements that included the photon spectra. It is 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 28 of 91

evident in these measurements that the vast majority of photon dose is higher energy photons with 

the exception of the plutonium facilities (308, 234-5) where 17 keV X-rays from plutonium and 60 keV 

photons from 241Am are significant. 

Table 6-9. Hanford workplace photon spectra measurements.

a

Facility Description Measurements Resultsb Reference

308 Bldg. Room Background Gamma 241Am (100%) Fix et al. 

Grinder Hood Bottom Gamma 1981 241Am (100%)

Pellet Pressing Station Gamma 241Am (100%)

327 Bldg. Background A-Cell Gamma 60Co (85%), 137Cs (8%), 54Mn (8%)

Background G-Cell Gamma 60Co (79%), 137Cs (9%), 54Mn (12%)

200W,2425 Evaporator Building, NE 

Corner

Gamma 137Cs (100%)

200W, Diversion 

Boxes

241-TX-302-C Catch Tank Gamma 137Cs (100%)

K2U Gamma 137Cs (100%)

Rigging Crew TLD (Beta, 

gamma)

High energy, indicative 

of photon radiation

B-Plant (225 Bldg) A-Cell Gamma 137Cs (100%)

Between B-C Cells Gamma 137Cs (100%)

Between D-E Cells Gamma 137Cs (100%)

F-Cell Gamma 137Cs (100%)

Room Background Gamma 137Cs (100%)

271B Pipe Gallery –Cell 9 TLD (Beta, 

gamma)

Indicative of 90Sr/90Y

324 Bldg. A-Cell Gallery Gamma 137Cs (100%) Fix et al. 

C-Cell Gallery Gamma 1982 137Cs (100%)

Truck Dock Gamma 137Cs (100%)

331 Bldg. Office Gamma 208Tl (90%), 137Cs(10%) 

Change Room (SE) Gamma 208Tl (8%), 137Cs(92%)

Change Room (Toilet) 208Tl (64%), 137Cs(36%)

Janitor’s closet 208Tl (46%), 137Cs(54%)

340 Bldg. 340-A Outside Gamma 137Cs (100%)

Control Room Gamma 137Cs (100%)

Decon Area Gamma 137Cs (100%)

Operations Office Gamma 137Cs (100%)

3730 Bldg Irradiation Room Gamma 60Co (100%)

Hallway Gamma 60Co (100%)

234-5 Fluorinator Hood Gamma <200 keV (99+%)

17 keV (~50%)

Roberson 

and 

Cummings 

1985

Photon Energy, keV

< 200 200-2000 >2000 

234-5, Vault 4 Vault 4 Entrance Gamma 13% 55% 33% Roberson 

and 

Cummings,

1986

234-5, Vault 1 Phantom Gamma 42% 55% 3%

floor Gamma 50% 48% 2%

Entrance Gamma 17% 61% 22%

234-5, MT Room At hoods near entrance Gamma 0% 83% 17%

234-5, C-Line, Room 

B 

 

Toward neutron source Gamma 92% 7% 1%

Toward room A Gamma 0% 98% 2%

Near Entrance Gamma 58% 28% 14%

a. Only measurements that included photon spectra are listed.

b. Measured non-natural radionuclide significant to occupational exposure. 

The extensive field validations of the Hanford film and HMPD in the late 1960s documented by 

Nichols et al. (1972) provide significant information on penetrating (PEN) and nonpenetrating (NPEN) 

dosimeter performance in several Hanford facilities and workplace conditions. The ratio of the 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 29 of 91

positive (i.e., non-zero) HMPD and film nonpenetrating to penetrating response is shown in Figure 6-

6. This figure implies generally higher ratios for the film in comparison to the HMPD. One reason for 

this is the routine use of uranium to calibrate the film as opposed to the use of 90Sr/90Y for the HMPD. 

As noted in Table 6-6, this results in TLD measurements that are higher than film measurements by a 

factor of two. As such, the respective film ratios in this figure should be divided by 2 for a direct 

comparison.

In addition, this figure shows that in all film dosimeter and TLD results, the reported NPEN dose was 

equal to or greater than the PEN dose (i.e., NPEN ≥ PEN).

0

5

10

15

20

0 1 2 3 4 5 6 7 8 9 10

HMPD, NPEN/PEN

Film, NPEN/PEN

TLD: NPEN/PEN => 1.0

Film: NPEN/PEN => 1.0

1:1

 Figure 6-6. Ratio of nonpenetrating (NPEN) to penetrating (PEN) dose for HMPD and 

 film parallel workplace measurements. 

6.4.5.3 Uncertainty in Beta/Photon Recorded Dose

Table 6-10 summarizes estimates of Hanford beta/photon personnel dosimeter parameters important 

to Hp(10) performance in the workplace. Based on the respective field and laboratory measurements, 

Hanford dosimeters reasonably measure the Hp(10) dose under most workplace radiation fields. The 

only process of concern is the potential under-response of the original two-element film dosimeter in 

plutonium facilities. It appears that the Hanford dosimetry staff was well aware of this issue. An 80-

keV X-ray calibration was used at least as early as 1946 (HEW 1946). Later, the penetrating dose 

was calculated as the sum of 20% of the OW response plus the 1-mm silver response (Fix, Wilson, 

and Baumgartner 1997). Hanford and IARC studies of the two-element dosimeter have shown an 

over-response of the actual Hp(10) dose by a factor of about 2 to photons greater than 100 keV. A 

favorable to claimant approach is proposed to ignore this over-response because of the complexity of 

workplace photon energies and exposure geometries that tend to result in an under-estimate of the 

Hp(10) dose. Minimal effect is expected from higher energy beta radiation contribution to the Hanford 

dosimeter penetrating dose response. The respective Hanford film dosimeters have filtration of 

approximately 1,000 mg/cm2 (nearly equivalent to 1-cm depth in tissue) for those regions of the 

dosimeter used to measure the whole-body dose.
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 30 of 91

 Table 6-10. Hanford workplace photon dosimeter Hp(10) performance. 

Parameter Description Biasa Workplace response

Exposure 

geometry

Hanford dosimeter 

system calibrated 

using AP laboratory 

irradiations. 

Workplace exposure 

geometries are highly 

variable.

> 100 keV: 

Two–element film 

Dosimeter, ~ +200%

Others, ±25%

< 100 keV: Likely too 

low.

Potential bias in recorded dose is variable 

since it is expected that most workers 

change position in the radiation field. It is 

expected that the highest doses are 

associated with AP geometry where the 

work is being performed close to the 

radiation source. Effect is highly 

dependent on radiation energy. 

Energy 

response

Response of 

dosimeter compared to 

tissue. 

Response for all 

dosimeters ±25% with 

the exception for the 

two-element dosimeter 

that is too high around 

100keV and too low 

around 17 keV.

Stated Hanford practice to include 1/5 of 

the shallow dose based on a 16-keV 

calibration to the deep dose for Hanford 

plutonium facilities workers could resolve 

this source of potential under-response. 

Mixed fields Dosimeters respond to 

beta and photon 

radiation.

Reasonable estimate 

of Hp(10) dose is 

expected.

Filtration of about 1,000 mg/cm2 over film 

dosimeter component used to calculate 

deep dose minimizes dosimeter response 

to beta radiation. 

Missed dose Doses less than MDL 

recorded as zero dose.

Recorded dose of 

record likely too low.

Hanford recorded doses < MDL for all 

years. The issue is significant, primarily 

in earlier years with frequent dosimeter 

exchange and film dosimeters with higher 

MDLs. 

Environmental 

effects

Workplace heat, 

humidity, etc., fades 

dosimeter signal. 

Recorded dose of 

record likely too low.

Hanford prepared calibration and 

personnel film at the same time, and 

irradiated calibration dosimeters for use in 

processing which would tend to maximize 

time for fading for calibration dosimeters 

but these dosimeters were not subject to 

the workplace environment. 

a. Bias represented as percent or as the recorded dose compared to Hp(10) based on judgment from laboratory and field 

measurements. 

Wilson et al. (1990) identified bias factors for the respective Hanford facilities using each of the 

Hanford dosimetry systems. They defined the bias factor to be a ratio of the Hp(10) dose to the 

recorded dose. These factors are presented in Table 6-11.

Fix, Gilbert, and Baumgartner (1994) conducted an evaluation of the historical Hanford dosimeter 

performance for photon energies > 100 keV, which is generally applicable to all Hanford workplaces 

with the exception of plutonium facilities. The approach used in this report can be considered an 

elaboration of the approach used to quantify the bias and uncertainty in estimated doses for personnel 

exposed to radiation as a result of atmospheric testing of nuclear weapons between 1945 and 1962 

(NRC 1989). The approach was developed by the National Research Council (NRC) Committee on 

Film Badge Dosimetry in Atmospheric Tests. It involved quantifying both bias and uncertainty from 

four sources and then combining them to obtain an overall assessment using methods used in the 

evaluation of bias and uncertainty for persons exposed to radiation from an atmospheric nuclear 

detonation (NRC 1989). In this approach, uncertainty is evaluated from laboratory uncertainty (i.e., 

calibration, processing), radiological uncertainty (i.e., spectrum, wearing, and backscatter), environmental uncertainty (i.e., consequences of light, moisture, and high temperatures), and uncertainty 

resulting from converting recorded measurements of exposure to estimates of deep dose. 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 31 of 91

Table 6-11. Uncertainty in beta/photon Hp(10) in Hanford facilities (Wilson et al. 1990).

Facility 

type

Beta/photon field 

description

Dosimeter 

type

Bias factor 

rangea

Min. Max. Comments

Fuel

fabrication

Uranium beta and 

gamma radiation

Two-element 

film

0.5 1.6 Recorded whole body dose approximates 

Hp(10) response results noted in this TBD.

Multipleelement film0.7 1.3

TLD 0.8 1.2

Reactor High energy beta 

and photon 

radiation.

Two-element 

film

0.5 1.7 Recorded whole body dose approximates 

Hp(10) response results noted in this TBD 

since predominant photon energy > 100 

keV. 

Multipleelement film0.7 1.4

TLD 0.8 1.2

Fuel

reprocessing

Generally mixed 

beta and photon 

radiation

Two-element 

film

0.5 1.6 Recorded whole body dose approximates 

Hp(10) response results noted in this TBD 

since predominant photon energy > 100 

keV.

Multipleelement film0.7 1.3

TLD 0.7 1.3

Plutonium

finishing

Predominant 

photon energy < 

100 keV.

Two-element 

film

(b) (b) Significant uncertainty is associated with 

dose estimates in low-energy photon 

Multiple- fields with the two-element dosimeter.

element film

1.0 2.0

TLD 0.6 1.4

Waste and

laboratory

Generally mixed 

beta and photon 

radiation

Two-element 

film

0.5 1.6 Recorded whole body dose closely 

approximates Hp(10) response results 

noted in this TBD since predominant 

photon energy > 100 keV.

Multipleelement film0.7 1.3

TLD 0.8 1.2

a. Bias factor defined as ratio of Hp(10) to recorded whole body photon dose.

b. No estimate provided by the authors.

The assessment at Hanford was based on the assumption that uncertainties from individual sources 

followed independent lognormal distributions. For each uncertainty source, a factor is assigned 

reflecting bias (B) and a 95% uncertainty factor (K); the uncertainty factor was determined so that the 

interval obtained by dividing and multiplying by this factor would include 95% of all observations. 

Assessment of these factors was based on careful evaluation of the available evidence, but because 

evidence was not adequate for rigorous statistical treatment of most uncertainties, subjective 

judgments were also required. Once the individual sources were evaluated, an overall bias factor was 

obtained by multiplication and an overall uncertainty factor obtained through lognormal propagation of 

errors. The results of this analysis for Hanford workers (for facilities other than plutonium facilities) 

are presented in Table 6-12.

Essentially all Hanford radiological work areas involved beta/photon radiation covering a wide range 

of energies characteristic of the radionuclides being handled in the respective facilities and processes. 

Radiation beta/photon fields characteristic of Hanford facilities can be generally classified according to 

the IREP code input, radiation types, and energy ranges based on Hanford field measurements, the 

types of radionuclides and processes in the respective Hanford facilities. This is presented in Table 6-

13.
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 32 of 91

Table 6-12. Overall bias and uncertainty due to variation and uncertainties regarding energy levels 

and geometry in recorded dose as an estimate of deep dose. 

Hanford dosimetry system

Bias magnitude and range Uncertainty factors

Overall biasa Range in biasb Systematicc Randomd

Two-element film (1944-56) 1.27 1.13–1.60 1.2 1.8

Multi-element film (1957-71) 1.02 0.86–1.12 1.1 1.4

Multi-element thermoluminescent (1972-83) 1.12 1.04–1.16 1.05 1.2

Multi-element thermoluminescent (1984-93) 1.01 0.95–1.05 1.05 1.2

a. Based on the distribution of energy levels and geometry judged most likely. Divide recorded dose by the table's bias 

value to calculate deep dose. Note that this use of bias factor does not apply to plutonium facilities.

b. Range of overall bias factors based on alternative distributions of energy levels and geometry.

c. Systematic uncertainty resulting from lack of knowledge regarding actual distributions of energy levels and geometry.

d. Random uncertainty resulting from variation among workers in energy levels and geometry.

Table 6-13. Selection of beta and photon radiation energies and percentages for Hanford facilities. 

Process/

Buildings Description

Operations

Radiation 

type

Energy 

selection, 

Begin End keV Percentage

Fuel 

fabrication

Produced reactor fuel and target assemblies from uranium. Beta

Photon

> 15 

30 – 250 

100%

313, 306, 333 1945 1972 100%

Reactors

During Operation: Highly dispersed fields of higher-energy 

photon radiation fields from fission process, activation and 

fission product nuclides. Potentially narrow beams of higher 

energy neutron radiation from test ports, etc., into reactor 

core. Potential for significant airborne nuclides and there 

may be significant higher-energy beta radiation. 

Beta 

photon

> 15 

30 – 250 

> 250 

100%

25%

75%

Not in Operation: Highly dispersed fields of higher energy

photon radiation fields from activation and fission product 

nuclides. No significant neutron radiation. There may be 

significant higher energy beta radiation during maintenance 

work resulting from fission products.

B-Reactor 9/26/44 1946

1948 2/12/68

D-Reactor 12/17/44 6/26/67

F-Reactor 2/23//45 6/25/65

H-Reactor 10/29/49 4/21/65

DR-Reactor 10/50 12/31/64

C-Reactor 11/18/52 4/25/69

KW-Reactor 12/54 2/1/70

KE-Reactor 2/55 1/28/71

N-Reactor 12/63 1/6/87

FFTF 2/9/80 12/93

Processing 

plants

Radiochemical Operations: Highly dispersed fields of 

higher energy photon radiation fields from activation and 

fission product nuclides dominant to most exposure profiles. 

Potential for higher energy beta radiation during sampling 

and maintenance work from fission products. 

Beta 

photon

> 15 

30 – 250 

> 250 

100%

25%

75%

T Plant 12/26/44 3/56

B Plant 4/13/45 1956

S Plant (Redox) 1/51 12/67

C Plant 7/52 7/67

A Plant (Purex) 1/56 6/72

1983 1988

U Plant 3/52 1/58

UO3 Plant 56

Plutonium 

production 

Plutonium Component Production: Plutonium is 

machined into weapon components using glove-box 

assembly process with predominant close anterior exposure 

to workers. Radiation characteristics in this area involve 

significant lower energy photons and neutron radiation.

Photon < 30

30 – 250 

25%

75%
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 33 of 91

Process/

Buildings Description

Operations

Radiation 

type

Energy 

selection, 

Begin End keV Percentage

Plutonium Storage: Radiation characteristics in this area 

generally involve dispersed lower energy neutron radiation 

and scattered photons, including 60-keV Am-241 gamma 

ray.

231-Z 1/16/45

Plutonium Finishing Plant (234-

5Z)

1949 1980

Calibrations

Hanford site calibration of 

instruments and dosimeters Beta 

photon

> 15 

30 – 250 

> 250 

100%

25%

3745-A, 318 1945 75%

Waste 

handling

Radiation characteristics highly dependent on source of 

waste, but typically fission product nuclides (Sr/Y-90, Cs137) are dominant. 

Beta 

photon

> 15

30 – 250 

> 250 

100%

50%

50% 200 East and West 1953

 Hanford documentation (Roberson, Cummings, and Fix 1985; Roberson and Cummings 1986; Rathbun 1989).

6.4.5.4 Hanford Neutron Dosimeter Response Testing

The HMPD was implemented on January 1, 1972. Hanford dosimetrists had conducted detailed field 

measurements in the early 1970s to base the calibration of the TLD on the neutron energy spectra in 

the work environment. Studies reported by Nichols et al. (1972) involved the simultaneous placement 

of NTA dosimeters and TLDs on 2-gallon polyethylene jugs filled with water and placed at selected 

workplace locations. A tissue equivalent proportional counter (TEPC) was used to measure the dose 

from fast neutrons. Data from Nichols et al. (1972), which are summarized in Table 6-14, indicate 

wide variability between the results for the different measurement techniques. However, the data 

illustrate the general under-response of the NTA film dosimeter results compared with the TEPC and 

TLD results. 

A second type of workplace measurement reported by Nichols et al. (1972) involved personnel 

wearing TLDs and film dosimeters simultaneously. Figure 6-7 shows the comparison of the fast 

neutron dose component from both dosimeter types. It is apparent in this figure that there is a 

significant lower neutron dose for the NTA dosimeter compared to the TLD neutron doses for TLD 

neutron doses greater than about 50 mrem.

Figure 6-8 shows the ratio of collective Hanford neutron dose to plutonium production. A slight 

increase in recorded neutron dose occurs in 1950 with the implementation of the NTA dosimeter. An 

increase occurs in the early 1960s, which conforms to the peak plutonium production years at 

Hanford. The significant peak in recorded neutron dose in 1972 is attributable to the large increase in 

recorded neutron dose with the HMPD. The HMPD responds to the thermal and intermediate neutron 

spectra that are not detected by the NTA film dosimeter. 

The AEC held a series of Personnel Neutron Dosimetry Workshops to address problems experienced 

by its sites concerning accurate measurement of neutron dose. The first workshop was held 

September 23–24, 1969 (Vallario, Hankins, and Unruh 1969), with the stated concern: “for 

intermediate energy (i.e., > 0.4 ev to < 700 keV) ... neutron sources, NTA personnel neutron 

dosimeters cannot be effectively used. This leaves a gap in the personnel dosimetry program which 

at many installations may be quite serious.” The workshops were generally limited to representatives 

from sites with active personnel neutron dosimetry programs and continued for a number of years. 

The 11th Workshop was held in 1991 (Rabovsky, Jones, and Pettengill 1991). The significance of the 

underestimated neutron dose became evident with studies being conducted to implement TLDs. 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 34 of 91

 Table 6-14. Parallel workplace measured NTA and HMPD 

 neutron dose. 

Fast neutron dose, millirem

Location Snoopy TEPC NTA TLD

105-KE

X-1 60 270 0 530

Top #23 1,400 1,700 470 4,100

Mon 0 0 0 60

Front face 50 900 0 250

308 Bldg.

Rm 208 2,000 2,700 270 3,700

Corr #7 4,200 14,100 1,270 11,100

Vent rm 30 30 0 0

Rm C 700 730 70 870

234-5Z Bldg.

17 DC 340 NM 0 100

HC-11 280 NM 0 180

9B top stairs 410 NM 100 440

9B under stairs 280 NM 60 450

Rm 221 410 790 170 460

Rm 192 510 620 950 490

Rm 192-C 150 230 310 240

Rm 193 380 500 770 600

2731-Z 200 NM 60 50

NM = not measured

0

100

200

300

400

500

600

700

0 100 200 300 400 500 600 700

N

T

A

,

m

r

e

m

TLD, mrem

 Figure 6-7. Comparison of Hanford PFP workplace NTA and HMPD neutron dose 

 (Nichols et al. 1972).
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 35 of 91

0

50

100

150

200

250

300

350

400

450

1940 1950 1960 1970 1980 1990 N

e

u

t

r

o

n

D

o

s

e

/

P

l

u

t

o

n

i

u

m

P

r

o

d

u

c

t

i

o

n

Year

PIC, NTA TLD 10B

 Figure 6-8. Ratio of annual Hanford collective neutron dose to plutonium production.

Following implementation of the HMPD on January 1, 1972, AEC headquarters staff conducted a 

detailed review of recorded neutron dose for Hanford personnel using a committee of technical 

experts from Hanford, SRS, and other AEC facilities (Biles 1972). Central to this investigation was the 

selection of 18 long-term Hanford workers for detailed evaluation. Fix, Wilson, and Baumgartner 

(1997b) analyzed this information using dosimetry data recorded through 1995. Table 6-15 lists three 

distinct periods of dose recording from 1950 through 1995 corresponding to the Hanford two-element, 

multielement, and thermoluminescent dosimeters. 

Table 6-15. Recording periods for selected Hanford plutonium workers. 

Period Description

1950–56 Involved use of original Hanford two-element dosimeter for nonpenetrating (shallow) and 

penetrating (deep) dose components and NTA film for neutron radiation. 

1957–71 Involved use of Hanford multielement film dosimeter for nonpenetrating, X-ray, and 

penetrating dose components, and NTA film for neutron radiation. 

1972–95 Involved use of Hanford TLD for beta, photon, and neutron dose components.

The 18 workers had the Hanford PFP as their primary work area at least during the 1970s. It is 

interesting to examine trends in this data. For example, Table 6-16 shows the ratios of recorded 

shallow to deep doses and recorded neutron to deep doses. The comparatively high shallow to deep 

ratio during the 1950-1956 period is likely to result from the significant over-response of this dosimeter 

to the low-energy photons prevalent in the PFP (Wilson et al. 1990). The data show increasing levels 

of recorded neutron dose, relative to the deep dose, for each succeeding dosimeter design. 

 Table 6-16. Ratio of recorded Hanford dose components. 

Ratio (range)

Recording period Shallow/deep Neutron/deep

1950–56 1.6 (1.1–3.7) 0.003 (0–0.06)

1957–71 1.2 (1.1–1.7) 0.4 (0.1–0.7)

1972–95 1.3 (1.1–1.5) 0.6 (0.1–1.6)

Moreover, it is possible to observe changes in relative dose components during (1) the 1957 period 

when the multielement film dosimeter was introduced along with the PuF4 neutron source calibration 

that provided a calibration spectrum similar to the Hanford plutonium workplace, and (2) during the 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 36 of 91

1972 period when the HMPD was introduced. Nine of the 18 workers examined by Fix, Wilson, and 

Baumgartner (1997) had dose histories that extended from 1950 or earlier through 1980 or later. 

6.4.5.5 Hanford Workplace Neutron Dosimeter Response

Work areas at Hanford where there is a potential for neutron exposure include: 

• 100 Area

– 105-B, 105-C, 105-D, 105-DR, 105-F, 105-H, 105-KE, 105-KW, 105-N reactors

• 200 Area

– 221-U facility cinder block building attachment (known as 271-U)

– 224-T facility to concentrate plutonium solutions and store sources

– 231-Z plutonium isolation facility

– 232-Z incinerator and leach facility

– 234-5Z primary plutonium handling facility

– 236-Z Recuplex/Plutonium Reclamation Facility

– 242-Z americium recovery facility

– 2736-Z plutonium vaults

• 300 Area 

– 308 Plutonium Fuels Pilot Plant (PFPP)

– 309 Plutonium Recycle Test Reactor (PRTR)

– 318 Radiological Calibrations Facility

– 324 Chemical and Materials Engineering Laboratory 

– 3745A Calibrations Laboratory

– 3745B Accelerator Facility

• 400 Area

– Fast Flux Test Facility (FFTF)

The circumstances of neutron exposure at these facilities are different and can be divided according 

to the facility of worker primary employment based on the method of primary neutron radiation 

generation. At the 200 and 300 Area plutonium facilities, neutron radiation is generated from 

plutonium either by spontaneous fission or, importantly, by alpha particle interaction with light 

elements such as oxygen, fluorine, and beryllium. These interactions are commonly referred to as 

alpha-n reactions. At the Hanford 100 and 400 Area nuclear reactor facilities, neutrons are generated 

by fission of uranium and plutonium in the reactor core. These two methods of neutron generation 

comprise the majority of the neutron exposure to workers at the Hanford site. As such, this TBD 

subdivides neutron exposure of workers according to these two general areas: 1) plutonium facilities 

and 2) reactor facilities. Neutron exposure at the 300 area laboratory facilities (e.g., 324) generally 

involved experiments related primarily to nuclear fuel development. This potential source of neutron 

radiation exposure of workers should be evaluated according to the two methods of neutron exposure 

(i.e., reactor or plutonium) that most closely fits the exposure pattern. There is little potential for 

significant unrecorded neutron dose in the 300 Area radiological calibration (318, 3745B) and 

accelerator (3745A) facilities because these are the facilities used to develop, test, and calibrate 

Hanford dosimetry and instrumentation systems.

Neutron spectra (Fix et al. 1981, 1982; Roberson, Cummings, and Fix 1985; Brackenbush, 

Baumgartner, and Fix 1991; Endres et al. 1996) and dose (Fix et al. 1981, 1982; Roberson, 

Cummings, and Fix 1985; Brackenbush, Baumgartner, and Fix 1991; Endres et al. 1996; Scherpelz, 

Fix, and Rathbone 2000) measurements have been performed at selected Hanford plutonium facilities 

on many occasions beginning in the 1970s with the availability of modern instrumentation. These 

measurements used several methods at different times to measure neutron dose, including TEPCs, 

which are considered to provide an accurate measurement of neutron dose (Brackenbush et al. 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 37 of 91

1991, Scherpelz et al. 2000), as well as portable neutron survey instruments (i.e., Snoopy, HMPDs, 

commercial TLDs, and TEDs). Energy spectrum measurements used multisphere (Bonner) sphere 

spectrometers, which are the primary system used, as well as 3

He spectrometers, and NE-213 liquid 

scintillation spectrometers. Table 6-17 summarizes Hanford reports that include measured neutron 

spectra. 

100 and 400 Area Reactor Facilities

There is a potential for workers to be exposed to neutron radiation in the Hanford reactors. These 

facilities generally have extensive shielding to reduce worker neutron and photon radiation exposure 

in most work areas. Neutron radiation is significant only while a reactor is in operation and only in 

areas of a reactor that are typically closed to general worker access. Neutron exposure of workers is 

accompanied by photon radiation that is readily measured with Hanford portable instruments, pocket 

ionization chambers, personnel film dosimeters, and later thermoluminescent dosimeters. In general, 

there is relatively little information concerning measured Hanford worker neutron dose using the NTA 

dosimeter in the single-pass production reactor facilities (B, C, D, DR, F, H, KE, KW) although there 

are substantial laboratory studies (Wilson et al. 1990). Operations of these reactors terminated prior 

to the Hanford-wide implementation of the HMPD in 1972. 

Table 6-17. Hanford workplace neutron spectra measurements.

a

Facility Description Measurementsa,b Reference

308 Bldg. Fuel Storage Pit Area MS, TEPC, Rascal, HMPD Fix et al. 1981

Plutonium Storage Vault MS, TEPC, Rascal

Fuel Pin Storage Box Area MS, TEPC, Rascal

Bare Fuel Assembly MS, TEPC, Rascal, HMPD

234-5Z Glovebox H-9A MS, TEPC, Snoopy, HMPD

Glovebox HC-9B MS, TEPC, Snoopy, HMPD

2736-Z Six locations in Bldg. MS, TEPC, Snoopy, HMPD

324 Bldg Pu Storage Vault MS, 3He, TEPC, HMPD Fix et al. 1982

FFTF Operating Deck MS, 3He, TEPC, HMPD, 

234-5Z Hood HA-23 Area Snoopy

2736-Z Storage Vault, Room 1 MS, TEPC, HMPD Roberson, 

Cummings and 

Fix 1985

Storage Vault, Room 4

236-ZZ Gloveboxes 5-6

234-5Z Process Line C, room B

234-5Z Pu metal, PuF4 and PuO2 with selected 

thicknesses of acrylic shielding

MS, TEPC, HMPD Brackenbush et 

al. 1991

234-5Z Frontside - Storeroom MS, TEPC, TLD, TED Endres et al.

Frontside - Near Shops 1996

Backside – glovebox

Backside – glovebox

Pu metal, PuF4 and PuO2 with selected 

thicknesses of acrylic shielding

a. Only measurements that included neutron spectra are listed.

b. MS = multi-sphere, TEPC = Tissue Equivalent Proportional Counter.

Worker exposure to neutron (and photon) radiation beams associated with instrument and test 

penetrations into the reactor core with the Hanford single-pass reactors that began operation in 1945

did occur. A report by Wilson (1956) summarizes the potential for significant neutron and photon

dose rates for these beams and the concern for significant neutron dose to the eyes of workers 

conducting instrument measurements of the reactor core. In 1960, Peterson and Smalley (1960) 

evaluated the neutron dose rates on the face of the B reactor at Hanford. The purpose of this 

evaluation was to develop a shielding method to reduce the neutron dose rate resulting from leakage 

through empty fuel tubes. As part of this analysis, they reported existing neutron and photon dose 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 38 of 91

rates for the various Hanford reactors and the estimated dose rates after adding external shielding. 

This information is summarized in Table 6-18. 

 Table 6-18. Estimated neutron and photon dose rates for Hanford reactor front face. 

Reactor

Prior to 1961 After adding external shielding Ratio 

reduction 

factor

Neutron

(mrem/hr)

Photon

(mrem/hr) Ratio

Neutron

(mrem/hr)

Photon

(mrem/hr) Ratio

B 25 25 1.00 2 20 0.10 10.0

C 30 25 1.20 2 20 0.10 12.0

D 5 25 0.20 1 20 0.05 4.0

DR 10 20 0.50 1 16 0.06 8.3

F 15 25 0.60 2 20 0.10 6.0

H 5 25 0.20 1 20 0.05 4.0

KE 3 7 0.43 - - -

KW 3 3 1.00 - - -

As shown in Table 6-18, the neutron to photon dose ratios for reactor areas reported by Peterson and 

Smalley are considerably higher than the average neutron to photon dose estimates of approximately 

5% reported in Wilson et al. (1990). This is likely the result of two competing factors. The first is that 

workers are typically only exposed to neutrons while working near the reactor core while the reactor is 

operating as in this example where measurements were made on the “front” face of the reactor and 

represent the maximum dose rate for “air” channels with minimal neutron shielding. The photon 

exposure occurs in multiple other locations and significantly during reactor maintenance when the 

reactor is shutdown and there is no neutron radiation. As a result, a reduced neutron to photon ratio 

is expected for workers in normal work activities compared to these measurements at the reactor front 

face only. The second factor is that the NTA film had an energy threshold of about 800 keV, whereas 

the measurements by Peterson and Smalley used the double moderator neutron dosimeter that has a 

BF3 detector. Fix et al. (1997b) described this Hanford instrument and others as well as a study by 

Unruh in 1962 in which a comparison of NTA film with BF3 measurements on the B reactor face was 

conducted. The NTA film under-responded to the neutron field indicating considerable neutron 

exposure below the 800 keV. The range of the under-response was between 10% to 100%. Nichols 

(1972) reported a comparison of NTA and TEPC (and HMPD) measurements at the KE reactor (Table 

6-14) and found that the NTA under-responded substantially. 

Neutron Energy Spectra. No neutron spectra measurements for workplaces in Hanford single-pass

reactors that operated from 1945 (100 B) through 1971 (100 KE) have been located. The 

measurements needed are during reactor operation. Field testing of HMPD and NTA film by Nichols 

et al. (1972) did include the 105-KE reactor. These results are shown in Table 6-14. Positive neutron 

dose was measured with the TLD and TEPC that was generally not recorded by the NTA film. 

Neutron spectrum measurements were made in the early 1980s at two locations at the FFTF in the 

400 Area (Fix et al. 1982) as shown in Figure 6-9. 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 39 of 91

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02

Energy, meV

Dose Equivalent, rem

FFTF #1

FFTF #2

 Figure 6-9. Neutron spectra for Hanford 400 Area FFTF. 

The data in Figure 6-9 may not be indicative of routine operations. At that time, a stainless-steel 

research thimble in one of the bundle tubes allowed neutrons to stream from the core to the head 

compartment. The neutron spectrum was highly scattered, resulting in significantly lower neutron 

energies. Highly scattered neutron fields are likely characteristic of Hanford single-pass reactor 

workplace fields and this resulted in the relatively low NTA measurements. The HMPD used in these 

measurements showed an over-response of about a factor of 6 compared to the multisphere 

measurements because of the highly degraded neutron spectrum. Although indirectly applicable, 

measurements of neutron spectra and dose, and personnel dosimeter performance in US nuclear 

power reactors reported by Endres et al. (1981) concluded that NTA emulsions are not sensitive to 

the leakage spectra that may be present in commercial power reactor plants. 

200 and 300 Area Plutonium Facilities

Plutonium production at Hanford began January 16, 1945 (Freer and Conway 1997) in what is often 

called Z-Plant or the PFP 231-Z Plutonium Isolation Facility located in the Hanford 200 Area. At that 

time, Hanford-produced plutonium nitrate was shipped to the Los Alamos National Laboratory for use 

in producing nuclear weapons. On July 5, 1949, the PFP 234-5Z facility provided the capability for 

Hanford to convert plutonium nitrate to metallic plutonium. The initial 234-5Z plutonium finishing 

equipment was termed the “Rubber Glove” line because it depended on personnel working with a 

series of 28 stainless-steel gloveboxes, 55 meters long, to move the plutonium mixtures manually 

through the finishing process (Fix, Wilson, and Baumgartner 1997b). 

On March 18, 1952, a Remote Mechanical A (RMA) Line began operation. The RMA Line performed 

all the process steps in Pu metal production and fabrication except Task 1 (feed make-up and 

purification), which continued in the 231-Z facility. The RMA Line was in six rooms at 234-5Z. In mid1957, the RMA Line was modified for a continuous calcination and hydrofluorination process that 

essentially handled the Task 1 activities previously done at 231Z (i.e., all processing tasks). Many 

projects were undertaken at PFP 234-5Z from 1957 to 1961 to accommodate the significant increase 

in throughput. The most significant of these were the construction of the remotely operated series of 

glove boxes (RMC) Button Line and the RMC Fabrication Line. Both of these began operation in the 

mid-1960s. The RMC Line (button and fabrication components) consisted of a completely selfcontained, remotely operated series of glove boxes similar to the RMA Line areas. 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 40 of 91

Neutron dose is associated with the overall Hanford plutonium production process in which plutonium 

from the respective processing facilities was brought into PFP as a liquid nitrate solution. At the PFP, 

plutonium was precipitated as an oxalate, converted to a fluoride, and reacted at high temperature 

with metallic calcium, forming the metal (Ballinger and Hall 1991). Neutron radiation was particularly 

enhanced during the fluorination step in the process because of plutonium fluoride (PuF4) alpha 

neutron (α,n) reactions. The Hanford 200 Area plutonium facility is still in operation serving the 

primary purpose of maintaining and storing plutonium. 

Research and development work with nuclear fuel has been done in the Hanford 300 Area particularly 

at the 308 bldg. PFPP, 309 bldg. PRTR, and in the 324 bldg. chemical and materials engineering hot 

cell laboratories. Pilot work was done in the 300 Area facilities in preparation for the 400 Area FFTF 

construction and operation. 

Neutron Energy Spectra. PuF4 is the most significant source, historically, of neutron exposure to 

workers in the Hanford 200 Area plutonium facilities. Figure 6-10 shows measurements by 

Brackenbush, Baumgartner, and Fix (1991) of a PuF4 source with no shielding, 2.54 cm of acrylic 

plastic, and 5.08 cm of acrylic plastic shielding between the source and the detector system to 

illustrate the effect on the plutonium spectrum of increasing thicknesses of the acrylic in the glovebox 

sides. A PuF4 source was used to calibrate Hanford personnel dosimeters beginning in 1958 (Fix, 

Wilson, and Baumgartner 1997). This figure shows that, although different neutron spectra were 

measured, similarities were observed in the general shape of the degraded PuF4 spectrum. The 

energy of the dose equivalent peak is centered at approximately 1 MeV. Similar plutonium source 

and acrylic shielding measurements were reported in Endres et al. (1996) in association with field 

evaluations of the Harshaw commercial TLD and TED system implemented on January 1, 1995. The 

results of these measurements led to the eventual elimination of the TED component in routine 

personnel monitoring because the TED substantially underestimated the neutron dose. This occurred 

because the TED did not respond to the substantial lower energy neutron spectrum from stored 

plutonium in the current Hanford PFP operation. There are many similarities between NTA film and 

TED characteristics, including physical size, direct neutron responding device, angular response, and 

a lower energy neutron response threshold. The TED has a significantly better energy threshold of 

about 100 keV compared to the NTA film threshold of about 700 keV, but showed unacceptable 

capabilities to measure neutron dose. 

Neutron radiation spectra measurements in Figure 6-11 are documented in Fix et al. (1981, Study 4) 

and in Roberson, Cummings, and Fix (1985) at the PFP 234-5Z Building “C” Line, Room B, selected 

gloveboxes, and the 2736-Z plutonium vault. The 234-5Z locations are where plutonium nitrate was 

converted to plutonium fluoride with the associated high neutron flux rates. This location provided the 

highest neutron flux rates at Hanford. The original data were depicted as dose equivalent rates; 

however, for simplicity of calculation, a 1-hour exposure was assumed to use dose equivalent. 

As noted in Roberson, Cummings, and Fix (1985), the HMPD was originally calibrated in neutron 

fields encountered in 234-5Z, and this calibration has been maintained over the years. As such, the 

estimate of personnel neutron dose equivalent has remained tied to the original measurements 

regardless of the neutron source used to calibrate the dosimeter. Table 6-19 lists the ratio between 

the HMPD measured dose and those measured with a Snoopy, TEPC, multisphere, and PNR-4 (i.e., 

common portable neutron instruments used to measure neutron dose based on 9-inch to 3-inch 

sphere ratio) as reported in Roberson, Cummings, and Fix (1985). In these measurements, the most 

significant observation is the generally close agreement in estimated dose between the HMPD and 

the respective instruments. In all of these measurements, the similarity in energy spectra with PuF4 in 

Figure 6-10 is evident.
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 41 of 91

Neutron spectrum measurements were made in the early 1980s at research and development 

laboratories in the 300 Area (Fix et al. 1982). Figure 6-12 shows measurements at selected locations 

including plutonium storage vaults in the 308 and 324 Buildings.

PuF4 Spectra Degradiation

1.00E-07

1.00E-06

1.00E-05

1.00E-04

1.00E-03

1.00E-02

1.00E-01

1.00E+00

1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02

Energy, MeV

Dose Equivalent, rem

Bare PuF4

2.54 cm Acrylic Shielding

5.08 cm Acrylic Shielding

 Figure 6-10. Degradation in neutron energy spectra for bare, 2.54 cm and 5.08 cm 

 of acrylic plastic shielding with neutron energy groups overlay. 

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02

Energy, MeV

Dose Equivalent, rem

234-5 Glove Box H-9A

234-5 Glove Box HC-9B

2736-Z Pu Vault

234-5, "C" Line

 Figure 6-11. Neutron energy spectra recorded at Hanford PFP 234-5Z “C” line, 

 glovebox, and plutonium storage vault. 

 Table 6-19. 200 Area workplace measurement comparisons with HMPD (Roberson, Cummings 

 and Fix 1985). 

Location

Ratio of HMPD dose to instrument dosea

Snoopy PNR-4b TEPC Multi-sphere

2736-Z, Storage Vault, Room 1 0.98 (0.37) 0.84 (0.18) 1.02 (0.18) 1.28 (0.24)

2736-Z, Storage Vault, Room 4 0.92 (0.14) 0.87 (0.56) 0.84 (0.10) 0.95 (0.13)

236-Z,Gloveboxes 5-6 0.85 (0.18) 0.95 (0.43) 1.03 (0.41) 1.13 (0.41)

234-5Z, Process Line C, room B 0.88 (0.28) 0.88 (0.21) 1.17 (0.26) 1.17 (0.25)

Average 0.90 (0.10) 0.87 (0.13) 0.92 (0.08) 1.05 (0.10)
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 42 of 91

a. Numbers in parentheses represent one-standard deviation.

b. Portable neutron REM instrument based on 9” to 3” sphere measurements.

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02

Energy, MeV

Dose Equivalent, rem

Bare Fuel Subassembly

Above Fuel Storage Pit

Pu Storage Vault

324 Pu Vault

 Figure 6-12. Neutron spectra for Hanford 308 and 324 facilities (Fix et al. 1982). 

6.4.5.6 Neutron to Photon Ratio

Considering the uncertainty in the neutron recorded dose at Hanford reactor and plutonium facilities 

prior to implementation of the HMPD in 1972 and the recommendations of the 1972 AEC review (Biles 

1972) of pre-1972 NTA neutron dose results in Hanford plutonium facilities, the recommended method 

to estimate dose to workers from neutron radiation is using a favorable to claimant neutron to photon 

ratio. The photon dose was reliably measured and essentially all significant Hanford neutron dose 

was accompanied by significant photon dose. Issues to be considered to arrive at a favorable to 

claimant ratio for pre-1972 Hanford facility operations with potential neutron exposure of workers are 

presented for each of the primary operating areas. 

100 Area Reactors. All of the Hanford single pass through reactors were shutdown prior to the 

implementation of the HMPD in 1972. Neutron film dosimeter results for 14 workers between 1950 

and 1961 are included in the retrospective analysis of Hanford personnel neutron dose discussed in 

Fix et al. (1997b). Of these 14 workers, 7 primarily worked at the Hanford reactors. This analysis 

reevaluated the neutron dose using five different methods. Method 1 used a gross track count (i.e., 

no background subtraction) and resulted in the highest neutron doses and correspondingly the 

highest neutron/photon ratios. Method 5 was believed to be the most technically accurate employing 

a background subtraction based on the standard deviation of the number of neutron tracks on the 

blank films. Table 6-20 provides a summary of the seven 100 area reactor facility workers and the 

associated neutron photon ratios by method. Since it is not known which method is the most 

accurate, all of the data in Table 6-20 was used in this analysis. The data closely fit a lognormal 

distribution as shown in Figure 6-13 with a geometric mean of 0.11, a geometric standard deviation of 

2.79, and an upper 95th percentile of 0.62. 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 43 of 91

 Table 6-20. Neutron/photon ratios for reactor workers identified in 

 PNNL-11196. 

Worker # Method 1 Method 2 Method 3 Method 4 Method 5

2 0.39 0.14 0.11 0.06 0.06

3 0.14 0.06 0.05 0.03 0.03

6 0.64 0.34 0.31 0.24 0.24

7 0.25 0.10 0.08 0.04 0.04

11 0.13 0.04 0.03 0.01 0.02

12 0.75 0.29 0.21 0.11 0.12

14 0.72 0.26 0.20 0.11 0.12

Neutron spectra measurements of the single pass Hanford reactors during operation have not been 

located. The under-response of the NTA film due to neutron energy can only be estimated. Nichols 

et al. (1972) showed that for the single 100 KE (Table 6-14) positive measured NTA dose 

measurement, the NTA film recorded 28% of the true neutron dose as measured by the TEPC. Most 

of the NTA measurements showed zero neutron dose, including the reactor front face measurement 

location used in measurements by Peterson and Smalley. To estimate the neutron-to-photon ratio, a 

factor of 28% was used to adjust the neutron to photon ratios from Table 6-20 to account for the 

unmeasured neutron dose. This resulted in a lognormal distribution as shown in Figure 6-14 with a 

geometric mean of 0.41, a geometric standard deviation of 2.79, and an upper 95th percentile of 2.22.

Standard Normal Deviate (z)

-3 -2 -1 0 1 2 3

Neutron / Photon Dose Ratio

0.01

0.1

1

 Figure 6-13. Lognormal plot of Table 6-20 data.
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 44 of 91

Neutron to Photon Dose Ratio

Frequency

0 1 2 3 4

0

2

4

6

8

Figure 6-14. Adjusted neutron/photon ratio for Hanford reactors.

Worker dose reconstruction research is underway at the Russian Mayak facility that had a similar role 

in the development of Russian nuclear weapons as Hanford has performed in the US. Five Mayak 

graphite moderated reactors that first operated in 1948 have a design similar to Hanford’s single-pass 

reactors with the exception that the fuel channels are placed vertically instead of horizontally and 

notably, fuel recharge is conducted while the reactors are operating. Estimates of the neutron to 

photon dose for these workers have been calculated by Smetanin et al. (2003) using Monte Carlo 

(i.e., Monte Carlo N-Particle radiation transport code) methods. The results are shown in Table 6-21 

for exposure scenarios while the fuel channels were closed and open. Although the reactor design 

and operating practices were somewhat different, the data in Table 6-21 support the favorable to 

claimant conclusion of the analysis used to estimate the favorable to claimant neutron-to-photon ratio 

for Hanford workers. The values reported by Smetanin et al. (2003) are less-than the values reported 

by Peterson and Smalley in Table 6-18, however, there was substantial variability noted in the neutron 

dose rate among the respective Hanford reactors. 

 Table 6-21. Ratio of neutron to photon dose for graphite 

 moderated reactor (Smetanin 2003). 

Reactor plate

Ratio of neutron to photon dose

Measured Calculated

Closed fuel channels 0.084 0.08

Open fuel channels 0.35 0.28

The purpose of the Peterson and Smalley report was to evaluate different shielding methods to 

reduce the neutron exposure on the face of the graphite reactors. It is not clear as to when the 

additional shielding recommendations identified in this report were implemented. Since the report 

was issued in July of 1960, and the first of the Hanford reactors were shutdown starting in 1964 with 

the last single pass reactor being shutdown in 1971, it is possible that the additional shielding was 

only installed in some reactors (later running reactors) and not installed in others. Until the installation 

time frame is identified, the favorable to claimant assumption that additional shielding was not 

installed prior to the reactor being shutdown is made. 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 45 of 91

Since the N-reactor involved a different design (non-single pass reactor) and was not started until 

December 1963, the neutron exposure problem would likely have been solved prior to startup. Thus, 

a reduced neutron-to-photon ratio is used for the N-Reactor. This reduction factor is based on the 

estimated reduction in neutron dose expected following the installation of additional shielding. The 

expected neutron photon reduction ratios are provided in Table 6-18. Since this resulted in a range of 

values, each of these factors were applied to the adjusted NTA film measurements and a combined 

data set was evaluated. Analysis of this combined data set also indicated a lognormal distribution 

with a geometric mean of 0.06, a geometric standard deviation of 3.00, and an upper 95th percentile 

of 0.37. 

200 and 300 Area Plutonium Facilities. To develop the neutron-to-photon ratio at Hanford’s 

plutonium facilities, detailed dosimetry data between 1972 and 1991 from 15 long term workers was 

evaluated. This comprised a total of 303 dosimetry results spread over a total of 146 monitoring 

periods. Only instances where both a positive photon and neutron dose measurements were 

recorded and equal to or greater than 20 mrem, respectively, were used to develop the neutron to 

photon ratio. This was done to avoid the effects of low-dose variation. A total of 186 dosimeter 

results were analyzed. The frequency distribution of the neutron-to-photon ratios is provided in Figure 

6-15. This analysis indicated a lognormal distribution resulted in the best statistical fit as shown in 

Figure 6-16. The geometric mean of the distribution is 0.73 and the geometric standard deviation is 

2.10. This resulted in an upper 95th percentile of 2.47. There is little potential for significant 

unrecorded neutron dose in the 300 Area calibration (3745B) and accelerator (3745A) facilities 

because these are the facilities used to develop, test, and calibrate Hanford dosimetry and 

instrumentation systems. 

Neutron to Photon Dose Ratio

Frequency

0 1 2 3 4 5 6

0

5

10

15

20

25

 Figure 6-15. Neutron/photon dose ratio distribution of Hanford plutonium 

 facility workers. 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 46 of 91

Standard Normal Deviate (z)

-3 -2 -1 0 1 2 3

Neutron / Photon Dose Ratio

0.1

1

10

 Figure 6-16. Lognormal distribution of data in Figure 6-15. 

Neutron to photon dose ratio distributions developed for Hanford reactor and plutonium facility 

workers are summarized in Table 6-22. These ratios should be applied after combining the recorded 

photon dose and the missed photon dose. It should be noted that if the energy employee has 

measured neutron dose, the neutron photon ratio should be compared to the values in Table 6-22. If 

the measured neutron dose resulted in a higher neutron to photon ratio compared to the geometric 

mean in Table 6-22, the claim-specific ratio should be used. 

Table 6-22. Hanford neutron to photon dose ratios.

a

Process Description/buildings

Neutron to photon ratio

Geometric 

mean

(GM)

Geometric standard 

deviation (GSD)

Upper 

95th%

Reactors During Reactor Operation: Low level neutron exposure through shielding on the face of the 

reactors and through test ports. 

B, D, F, H, DR, C, KW, KE Reactors 0.41 2.79 2.23

N Reactor 0.06 3.00 0.37

Plutonium 

production

Plutonium Finishing Process: Plutonium enters the process as PuF4 and is then fired into 

production pucks. Work is primarily conducted in glove boxes with predominant close anterior 

exposure to workers. Radiation levels at the beginning of the process are fairly constant while 

levels at end of process are closely related to production levels. 

Plutonium Facilities (200 Areas)

(224-T, 231-Z, 232-Z, 234-5Z, 236-Z, 

242-Z, 2736-Z, 271-U) 0.73 2.10 2.47 

Plutonium Laboratories (300 Area)

(308, 309, 324)

a. Applicable to facilities with significant potential for neutron exposure and prior to TLD use. 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 47 of 91

6.4.5.7 Neutron Dose Fraction

The fraction of the total dose in each neutron energy group shown in Figures 6-9, 6-10, 6-11, and 6-

12 (see overlays in figures) was determined by subdividing the neutron spectra into the four lower 

neutron energy groups discussed in the External Dose Reconstruction Implementation Guideline 

(NIOSH 2002). The highest neutron energy group (>20 MeV) was not used because operations at 

Hanford did not produce a significant component of neutrons of this energy. The dose for each 

neutron energy group was calculated by multiplying the neutron flux (Ø) provided in the references by 

Roberson, Cummings, and Fix (1985) and Brackenbush, Baumgartner, and Fix (1991) by the 

corresponding flux to dose-rate conversion factors (DCF) found in National Council on Radiation 

Protection and Measurements (NCRP) Report 38 (NCRP 1971). The neutron doses in each NCRP 

38 energy interval are summed to develop the four neutron group doses. The dose fraction (Df) for 

each neutron energy group (n) was calculated by dividing the neutron group dose by the total dose 

(DT). 

T

i

ii

nf D

E DCF

ED

∑

=

)(

)(

φ

(6-1)

where:

Ø(Ei) = Neutron flux of the ith energy bin;

DCFi = NCRP 38 (1971) flux to dose-rate conversion factor for the ith energy bin;

DT = Total dose.

Table 6-23 lists the neutron dose fractions by energy group using data measured by Roberson, 

Cummings, and Fix (1985). 

Table 6-23. Laboratory-measured dose fractions from PuF4.

Neutron 

energy group

Shielding of PuF4 sourcea

0 cm (Bare) 2.54 cm 5.08 cm

< 10 keV 0.00 0.00 0.01

10–100 keV 0.00 0.00 0.00

0.1–2 MeV 0.06 0.85 0.89

2–20 MeV 0.94 0.15 0.10

Favorable to claimant dose fractions

0.1–2 MeV 0.1 0.9 0.9

2–20 MeV 0.9 0.1 0.1

a. Thickness of acrylic shielding between source and detector

Table 6-24 lists selected neutron dose fractions by energy group using the measured neutron spectra 

or 200 Area PFP vault and glovebox locations presented in Fix et al. (1981) and Roberson, 

Cummings, and Fix (1985). The estimated default dose fractions for these PFP locations are similar 

to the 2.54- and 5.08-cm acrylic plastic shielded spectra shown in Figure 6-10. 

Table 6-25 lists selected neutron dose fractions by energy group using the measured neutron spectra 

for 300 Area locations presented in Fix et al. (1982).
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 48 of 91

 Table 6-24. 200 Area measured dose fractions. 

Energy group Glovebox H-9B

Glovebox 

HC-9B 2736Z Vault

234-5Z C 

Room B

< 10 keV 0.03 0.02 0.05 0.02

10–100 keV 0.04 0.04 0.04 0.03

0.1–2 MeV 0.84 0.87 0.80 0.88

2–20 MeV 0.09 0.07 0.11 0.07

Favorable to claimant dose fraction default values

0.1–2 MeV 0.9 0.9 0.9 0.9

2–20 MeV 0.1 0.1 0.1 0.1

 Table 6-25. 300 Area measured dose fractions. 

Energy group

308–Bare fuel 

subassembly

308–Above fuel 

storage pit

308–Pu storage 

vault 324 Pu vault

< 10 keV 0.00 0.02 0.01 0.02

10–100 keV 0.00 0.04 0.03 0.03

0.1–2 MeV 0.64 0.73 0.75 0.88

2–20 MeV 0.36 0.21 0.21 0.07

Favorable to claimant dose fraction default values

0.1–2 MeV 0.6 0.8 0.8 0.9

2–20 MeV 0.4 0.2 0.2 0.1

Table 6-26 lists selected neutron dose fractions by energy group using the measured neutron 

spectra for 400 Area FFTF locations presented in Fix et al. (1982). As reported in Fix et al. 

(1982), these measurements were taken at a time when a stainless steel research thimble was in 

one of the tubes and allowed neutrons to stream from the core to the head compartment. This is 

not a usual operating mode. Even with the streaming, the spectra show significantly reduced 

energy because of scatter.

 

 Table 6-26. 400 Area measured dose fractions. 

Energy group FFTF #1 FFTF #2

< 10 keV 0.4 0.3

10–100 keV 0.5 0.4

0.1–2 MeV 0.1 0.3

2–20 MeV 0.0 0.0

Favorable to claimant dose fraction default 

values

10–100 keV 0.5 0.5

0.1–2 MeV 0.5 0.5

The Radiation Effectiveness Factors used in the IREP to calculate the POC are less for the 10-100-

keV category compared to the primary fission spectrum energy group (0.1 – 2 MeV) (Kocher, 

Apostoaei, and Hoffman 2002). Combining neutron energy groups into the primary 0.1 – 2 MeV 

fission spectrum group is a reasonable and favorable to claimant simplification of the dose calculation. 

The tables described above include the neutron energy favorable to claimant default values. 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 49 of 91

6.4.5.8 Uncertainty in Neutron Dose

Measurement of neutron dose in the workplace is difficult (Brackenbush, Baumgartner, and Fix 1991). 

Table 6-27 summarizes Hanford workplace neutron dosimeter performance characteristics. An 

evaluation of neutron dosimeter response in Hanford workplaces is presented in Fix, Wilson, and 

Baumgartner (1997b). The history is complicated, but the significant under-response in recorded 

dose with NTA dosimeters became evident in the late 1960s at several sites preparing to implement 

the TLD neutron dosimeters. 

Table 6-27. Uncertainty in neutron Hp(10) in Hanford facilities. 

Parameter Description Workplace response 

Workplace 

neutron 

energy 

spectra

NTA dosimeter response decreases 

and TLD response increases with 

decreasing neutron energy.

Depends on workplace neutron spectra. NTA 

recorded dose of record likely too low. Nichols 

et al. (1972) showed significant under-response. 

Exposure 

geometry

NTA dosimeter response increases 

with increasing exposure angle 

(Kathren, Prevo, and Block 1964) 

and TLD response decreases with 

increasing exposure angle. 

Effect is highly dependent on neutron energy. 

NTA recorded dose probably too high because 

dosimeter response is higher at angles other 

than AP. TLD recorded dose of record probably 

too low because dosimeter response is lower at 

angles other than AP.

Dosimeter 

Placement

Hanford instructed workers to wear 

neutron dosimeters close to body. 

No effect noted for laboratory studies of NTA 

film irradiations in-air or on-phantom. However, 

there is significant dependence in HMPD 

response (Kocher et al. 1971) as a function of 

distance from worker body. Recorded dose of 

record probably too low. 

Mixed lowenergy 

photon and 

neutron 

radiation

NTA dosimeter responds significantly 

to lower-energy photons that can 

result in fogging NTA film.

NTA-recorded dose of record probably too low. 

HMPD five-chip TLDs have capability to remove 

photon dose contribution accurately. However, 

HMPD 4-chip TLD under-estimates total dose in 

plutonium facilities by about 25%. 

6.5 ADJUSTMENTS TO RECORDED NEUTRON DOSE

Adjustments to the Hanford recorded neutron dose are necessary to arrive at a favorable to claimant

dose considering the uncertainty associated with the recorded dose in the complex Hanford 

workplace radiation fields and the variability in exposure circumstances. 

6.5.1

Hanford incorporated the energy variation of the dose equivalent into its calibration methodology. As 

a result, the recorded dose equivalent (DER) is a combination of all neutron energies. To calculate the 

POC, the recorded neutron dose must be separated into neutron energy groups, as discussed in 

Sections 6.3.4.6 and 6.3.4.7 and later converted to International Committee for Radiological 

Protection (ICRP) Publication 60 (ICRP 1990) methodology. 

Neutron Dose Adjustments

6.5.2

Adjustment to the neutron dose is necessary to account for the change in neutron quality factors 

between historical and current scientific guidance as described in NIOSH (2002). Hanford neutron 

calibration factors determined from National Institute of Standards and Technology (NIST)-calibrated 

sources are used directly without modification for field conditions (Brackenbush, Baumgartner, and Fix 

1991). The quality factor is incorporated in the NIST calibration methodology, which used flux-toNeutron Weighting Factor
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 50 of 91

dose-rate conversion factors for varying neutron energies for each calibration source. Flux-to-doserate conversion factors were based on NCRP Report 38 (NCRP 1971). The NCRP report lists both 

flux-to-dose-rate conversion factors and associated quality factors that vary from 2 at energies less 

than 1 keV to 11 at 1 MeV. To convert from NCRP 38 quality factors to ICRP Publication 60 (ICRP 

1990) radiation weighting factors, a curve was fit describing the neutron quality factors as a function of 

neutron energy. The average quality factor for each neutron energy group was developed by 

integrating the area under the curve and dividing by the neutron energy range as shown in equation 6-

2. 

)1.00.2(

)(

)(

0.2

1.0

0.21.0, − =

∫ − Range

EQ dE

EQ

f

n MeV (6-2)

Table 6-28 summarizes historical changes in the quality factors and the average NCRP 38 quality 

factor for the neutron energy groups used in dose reconstruction (See also ORAUT-OTIB-0055

[ORAUT 2006]). 

Table 6-28. Historical neutron quality or weighting factors. 

Neutron energy

(MeV)

Historical 

dosimetry

guidelinesa

NCRP Report 38 

group 

averaged quality

factorb

ICRP Publication 

60 neutron 

weighting 

factor

Ratioc

Thermal 3 2.35 5 2.13

0.5 eV - 10 keV 10

10 keV - 100 keV 5.38 10 1.86

100 keV - 2 MeV 10.49 20 1.91

2 MeV – 20 MeV 7.56 10 1.32

20 MeV - 60 MeV 6.96d 5 1.00e

a. First Tripartite Conference at Chalk River in 1949 (Warren et al. 1949; Fix, Gilbert, and Baumgartner 1994) and NCRP 

Report 17 (NCRP 1954; Taylor 1971).

b. See Figure 3-1.

c. Ratio of the ICRP 60 weighting factor to the group averaged NCRP38 quality factor each neutron energy group. 

d. “Not applicable” is usually inserted here rather than the NCRP group averaged value of 6.96, which is larger than the 

ICRP 60 weighting factor of 5 for 20-to-60-MeV neutrons and results in a non favorable to claimant reduction in the 

corrected dose for this neutron energy group.

e. Ratio for adjusting neutron dose from NCRP 38 quality factor to ICRP 60 weighting factor is arbitrarily set equal to unity 

to avoid a non favorable to claimant reduction in the corrected dose for this neutron energy group.

6.5.3

Table 6-28 lists the average quality factor for the four neutron energy groups that encompass Hanford 

neutron exposures. The neutron dose equivalent correction factor can be calculated by dividing the 

dose fractions from Section 6.3.4.4 for each neutron energy group (Df(En)) by the corresponding 

energy specific average NCRP Report 38 (NCRP 1971) quality factor (Q(En)) and then multiplying by 

the ICRP Publication 60 (ICRP 1990) radiation weighting factor (wR), as shown in equation 6-3. 

Neutron Correction Factor

R

n

nf

nf w

EQ

ED EC ×=

)(

)( )( (6-3)

Table 6-29 summarizes the favorable to claimant default neutron dose fractions by energy for Hanford 

work areas where field measurements of neutron spectra were performed using the associated ICRP 

60 correction factors. It should be noted that since a spectra was not available for the single pass 

reactors, the favorable to claimant assumption of 100% fission spectrum neutrons (0.1 -2 MeV) was 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 51 of 91

used. The neutron dose equivalent is calculated by multiplying the recorded neutron dose by the 

area-specific correction factors. For example, consider a 1,000-millirem recorded neutron dose by a 

worker at the PFP, the corrected neutron dose is 1,710 millirem from neutrons between 0.1-2.0 MeV 

estimated to represent 90% of the dose fraction (i.e., 1,000 * 1.71) and 130 millirem from neutrons 

with energy between 2 and 20 MeV estimated to represent 10% of the dose fraction (i.e., 1,000 * 

0.13). Thus, the corrected neutron dose is a total of 1,840 millirem. These adjustments should be 

applied to measured dose, missed dose, and dose determined based on a neutron-to-photon ratio. 

Table 6-29. Hanford Facility dose fractions and associated ICRP 60 correction factors. 

Process Description/buildings

Neutron energy

(MeV)

Default dose 

fraction

(%)

ICRP 60 

correction 

factor

Reactors During Reactor Operation: Low level neutron exposure through shielding on the face of 

the reactors and through test ports. 

B, D, F, H, DR, C, KW, KE, N 0.1-2 MeV 100% 1.91

FFTF 0.1-2 MeV

2-20 MeV

50%

50%

0.95

0.65

Plutonium 

production

Plutonium Finishing Process: Plutonium enters the process as PuF4 and is then fired into 

production pucks. Work is primarily conducted in glove boxes with predominant close 

anterior exposure to workers. Radiation levels at the beginning of the process are fairly 

constant while levels at end of process are closely related to production levels. 

Plutonium Facilities (200 Areas)

(224-T, 231-Z, 232-Z, 234-5Z, 236-Z, 

242-Z, 2736-Z, 271-U) 0.1-2 MeV

2-20 MeV

90%

10%

1.71

0.13 Plutonium Laboratories (300 Area)

(308, 309, 324)

6.6 MISSED DOSE

There is undoubtedly missed recorded dose for Hanford workers. The analysis has been separated 

according to photon and neutron missed dose. 

6.6.1

Missed photon dose for Hanford workers would occur where (1) there is no recorded dose because 

workers were not monitored or the dose is otherwise unavailable, and (2) a zero dose is recorded for 

the dosimeter systems for any response less than the site dose recording threshold. Methods to be 

considered if there is no recorded dose for a period during a working career have been examined by 

Watson et al. (1994). In general, estimates of the missed dose can use dose results for coworkers or 

the recorded dose before and after the period of missed dose. However, these situations require 

careful examination. The missed dose for dosimeter results is particularly important for earlier years 

when recording thresholds were higher and dosimeter exchange was more frequent. 

Photon Missed Dose

NIOSH (2002) describes options to calculate the missed dose. The recommended option is to 

estimate a favorable to claimant potential missed dose where MDL/2 is multiplied by the number of 

zero or less-than MDL/2 dose results. The following sections describe potential missed photon dose 

adjustments according to year, facility/location, dosimeter type, and energy range.

6.6.1.1 Year

Analysis of the missed photon dose according to year (actually by period according to dosimeter type 

and exchange) is needed to evaluate the claim information, particularly if only annual dose data are 

available. The MDLs for the Hanford beta and photon dosimeters normally cited are based on 

laboratory irradiations. Actual MDLs are higher because of additional uncertainty in actual field use 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 52 of 91

and the use of dose recording thresholds. Table 6-30 summarizes the potential missed dose. 

Reasonable MDLs are listed in this table for most applications for film dosimeters based on Wilson 

(1960b, 1987), NIOSH (1993), NRC (1989), and Wilson et al. (1990) and for TLDs from Fix et al. 

(1982) and Rathbone (2002). 

Table 6-30. Hanford photon dosimeter period of use, type, MDL, exchange frequency, and potential

annual missed dose. 

Period of usea Dosimeter

MDLb

(rem)

Exchange 

frequency

Annual 

missed dose 

(rem)c

Hanford beta/photon dosimeters

Prior to October 1944 PIC 0.005 Dailyd (n=250) 0.625

October 1944 - December 1950 Hanford two-element 

film

0.040 Weekly (n=52) 1.040

January 1951 - March 1957 0.040 Biweekly (n=26) 0.520

April 1957 - May 1957 Hanford multi-element 

film

0.040 Biweekly (n=26) 0.520

May 1957 - December 1971 0.040 Monthly (n=12) 0.240

January 1972 - December 1994 Hanford TLD 0.020 Monthly (n=12) 0.120

0.020 Quarterly (n=4) 0.040

January 1995 to 2003 (ongoing) Harshaw TLD 0.010 Monthly (n=12) 0.060

0.010 Quarterly (n=4) 0.020

a. For many years, Hanford workers had a dosimeter assigned to each operating area where they worked.

b. Estimated MDLs for each dosimeter technology in the workplace. Dose values were recorded at levels 

less-than the MDL

c. Annual missed dose calculated using MDL/2 from OCAS-IG-001 (NIOSH 2002). 

d. Not routinely exchanged.

6.6.2

Neutron radiation was present in the Hanford 100 Area reactors; 400 Area FFTF; 300 Area 

accelerator (3754B) and calibrations (3745A and 318 Buildings); and 200 and 300 Area plutonium 

facilities. There is potential for significant missed neutron dose among workers in the plutonium 

facilities where workers separated and finished plutonium (i.e., 224-T, 231-Z, 232-Z, 234-5Z, 236-Z, 

242-Z, 2736-Z, 271-U, 308 Plutonium Fabrication Pilot Plan, 309 PRTR, and 324 laboratory) for use in 

nuclear weapons. Workers were in close proximity to the plutonium and in the early years actually 

physically moved the plutonium from one work location to the next. The approach recommended for 

use to calculate the neutron missed dose can be divided into two periods. The first period is prior to 

1972 when ineffective PICs with 10B enriched liners and NTA film dosimeters were used. In this case, 

the missed dose is calculated from the photon dosimeter MDL and, using a neutron to photon ratio, 

provided in Table 6-22. The second period is post 1971 when the HMPD was used. In this case, the 

missing dose is based on the MDL of the dosimeter. Table 6-31 summarizes the reported limits of 

detection or dose recording thresholds. 

Neutron Missed Dose

Table 6-31. Hanford neutron dosimeter period of use, type, MDL, exchange frequency, and potential 

annual missed dose. 

Period of use Dosimeter

Exchange 

frequency

MDL 

(rem)a

Annual 

missed dose

(rem)b

October 1944–December 1949 PICs with 10B enriched 

liners

Dailyc (n=250) 0.010 1.300

January 1950–December 1950 NTA Weekly (n=52) 0.080 2.100

January 1951–March 1957 Biweekly (n=26) 0.080 1.000

April 1957–May 1957 Biweekly (n=26) 0.080 1.000

May 1957–December 1971 Monthly (n=12) 0.080 0.500

TLD Dosimeter
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 53 of 91

January 1972– December 

1994

HMPD – 4 or 5 chips Monthly 0.050 0.300

 January 1995-present Harshaw TLD Monthly 0.015 0.100

a. Estimated film dosimeter photon radiation detection levels before 1972 and neutron dosimeter MDLs after 1971.

b. Annual missed neutron dose calculated using: Prior to 1972, neutron to photon ratio after combining the recorded and 

missed photon dose. The actual estimate of annual missed dose will be the product of two lognormal distributions. 

After 1971, the lognormal distribution from the neutron dosimeter using a geometric mean of (n * MDL/2) and an upper 

95% confidence interval of (n * MDL), where n is the number of missing dosimeter results.

c. Dosimeter not routinely assigned. 

6.6.2.1 Year

Table 6-33 lists the potential missed dose for two distinct periods that are identified for correction to 

Hanford neutron dose results as described in the following paragraphs.

Before 1972. There is no recorded neutron dose prior to 1950 when 10B-lined PICs were used. 

Recorded neutron dose using the NTA film will likely significantly underestimate the actual neutron 

dose (Fix, Wilson, and Baumgartner 1997). 

Due to the uncertainty in whether an employee’s NTA badge would respond to the workplace neutron 

spectrum, using a ratio of the neutron-to-photon dose is a favorable to claimant option to reconstruct 

an individual worker neutron dose. This is based on the fact that routine neutron exposure is 

essentially always accompanied with measurable photon exposure (Watson 1959). The approach is 

illustrated as:

Neutron dose = photon dose * neutron/photon dose ratio

The 95th percentile neutron/photon dose ratio can be used to estimate the maximum missed neutron 

dose. The photon dose should be adjusted for any missed dose before an estimation of the missed 

neutron dose.

After 1971. The HMPD is sensitive to neutron radiation in Hanford workplaces with potential for

neutron radiation. Estimates of the missed neutron dose for the HMPD dosimeter is based on the 

respective dosimeter exchange periods and MDL/2. 

6.6.2.2 Facility/Location

Table 6-31 lists the potential missed neutron dose for the MDL and exchange frequency using NIOSH 

(2002). 

6.6.2.3 Dosimeter Type

The potential missed dose for neutron dosimeters depends strongly on the neutron radiation field in 

Hanford facilities. The MDLs are different for the Hanford neutron dosimeters cited based on 

laboratory irradiations. The actual MDLs are greater than these values because of additional 

uncertainty in actual field use and the use of dose recording thresholds. Reasonable MDLs are 

shown in Table 6-31 for most applications for film dosimeters based on Wilson (1960b, 1987), NIOSH 

(1993), NRC (1989), and Wilson et al. (1990) and for TLDs from Fix et al. (1982) and Rathbone 

(2002). 

6.6.2.4 Energy Range

An estimate of the missed neutron dose by energy range is possible based on the type of facility and 

predominant neutron energies measured during field measurements. The recorded neutron dose 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 54 of 91

from the HMPD and commercial TLD response does not provide enough information to estimate 

discrete energy ranges. Based on workplace spectra measurements, the default values for Hanford 

plutonium facilities are assumed to be applicable to nonplutonium facilities, even though the actual 

measured spectra would be expected to be different. A favorable to claimant default is proposed 

because there are not sufficient workplace spectra measurements in the reactor facilities; this 

approach simplifies the dose calculation. The values are listed in Table 6-31. 

6.7 UNCERTAINTY

There is significant uncertainty in evaluating dose recorded decades into the past. Primary issues 

concern the missed dose for zero recorded doses and the uncertainty in the positive doses, 

particularly low values, as described in the following sections.

6.7.1

Some considerations to evaluate dose to workers with low occupational exposure are examined in 

Wilson et al. (1990). The analysis of missed dose is typically based on the penetrating dosimeter 

response to a high energy calibration source such as 226Ra or 137Cs. For these energies, the nonpenetrating and penetrating dosimeter response is the same. In routine practice, the non-penetrating 

dose response is typically higher because of its response to low energy photon and beta radiation. 

Hanford work areas have mixed fields of radiation particularly involving scattered photon radiation of 

high and low energies and in some areas, beta radiation. As such, the non-penetrating dose recorded 

for workers provides a more sensitive means to determine if significant exposure has occurred. Also, 

the dosimeter response to low-energy photon radiation is significantly greater than for the high energy 

gamma radiation. There is concern for work performed close to sources of radiation such as repairing 

contaminated equipment, but typically workers would be assigned extremity dosimeters in addition to 

the whole-body dosimeters. The combination of the dose results measured by the extremity and 

whole-body dosimeter tend to lower the actual detection level in Hanford workplaces compared to an 

evaluation of the penetrating dose component only as described in the following paragraph. Figure 6-

17 presents an illustration of the respective Hanford dose results for a single worker from 1948 

through 1976. The tracking of the respective dose components is evident.

Missed Dose

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500

6000

6500

7000

7500

8000

1945 1950 1955 1960 1965 1970 1975 1980

Year

Dose, mrem

 NonPenetrating Dose

Penetrating Dose

 Neutron Dose

Extremity Dose

X-ray Dose

Two-Element Film Multi-Element Film TLD

 Figure 6-17. Annual dose components for a single Hanford worker, 1948-1976. 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 55 of 91

Wilson (1960b) conducted a detailed examination of the MDL for the Hanford dosimetry system used 

in 1960. The Hanford multi-element film dosimeter implemented in 1957 included the OW and 1 mm 

Ag filtered regions of the two-element film dosimeter used at Hanford from 1944 to 1957 so studies of 

this dosimeter can be extrapolated to earlier results. Wilson described three changes in 1960 that led 

to a lower detection level of about 15 mrem at the 90% confidence level involving: (1) elimination of 

non-isotropic effect of calibration source, (2) automated film processing and (3) change to the more 

sensitive 508 film. He notes in this report a detection level of 40 mrem at the 95% confidence level for 

the Hanford system (502 film) prior to these changes. An important consideration in this analysis 

concerned the level of potential missed dose. Wilson describes the analysis of 49 batches of Hanford 

routine calibration results that indicated a 25% standard deviation at the 30 mrem calibration level 

based on the optical density readings. Based on an analysis of the capabilities of the densitometer 

used to process the film, he estimated a likelihood of 0.33 (1/3) that a dose of 15 mrem would not be 

detected. The likelihood that this would occur for each successive monthly exchange for an entire 

year would be (0.33)12 or about one in a million. Based on the 13 exchanges during the year at that 

time, he estimated a maximum potential missed dose of 195 mrem (i.e., 15 * 13). Conversely, Wilson 

estimated that about 8% of the time, a positive dose would be recorded for dosimeters that received 

no exposure. A similar analysis could be performed for the dosimeter used prior to 1960 with an 

estimate that about 30 mrem would be detected 1/3 of the time. 

Assumptions favorable to claimants have been incorporated in the assessment of missed dose for 

zero recorded penetrating dose for the respective dosimeter exchange periods in this TBD. Hanford

did use a practice of locating dosimeters at the badge control building for each operating area for 

each person expected to routinely enter. As such, some Hanford workers had dosimeters 

simultaneously located at several different Hanford areas. Dosimeters from each of these areas were 

processed and a dose assigned to the worker. In many cases, a zero dose was recorded for all the 

dosimeters. Assuming a worker had dosimeters at seven Hanford work areas and using the 40 mrem 

MDL as noted in the respective tables of this TBD, it is possible to calculate a maximum potential 

missed dose of 140 mrem (i.e., 7 * 40/2) using OCAS-IG-001 (NIOSH 2002) for each exchange period 

or, if this occurs throughout the year, a maximum potential missed dose of 1,680, 3,360 and 6,720 

mrem, respectively, for monthly, biweekly, and weekly exchange periods. Often, the dose for a 

person with zero recorded dose will unrealistically exceed the dose for workers with recorded positive 

dose. It is recommended in this TBD that the guidance of OCAS-IG-001 (NIOSH 2002) be applied to 

the recorded dose for each exchange period regardless of the number of dosimeters assigned to a 

worker for each operating area. Using the analysis of Wilson (1990), the likelihood of all dosimeters 

reading zero for an exchange period when there is positive dose can be calculated as (0.33)y

 where y 

is the number of areas. 

6.7.2

Uncertainty in the positive recorded photon dose for Hanford workers has been assessed in Wilson et 

al. (1990) and, for photon radiation > 100 keV, by Fix, Gilbert and Baumgartner (1994). Results of 

these evaluations are noted in Tables 6-11 and 6-12. For the >100 keV photon radiation 

characteristic of all Hanford work areas with the exception of the plutonium handling facilities, the 

estimates of bias and uncertainty are primarily associated with the respective dosimeter systems. 

These estimates are summarized in Table 6-32. 

Positive Recorded Photon Dose

Table 6-32. Overall estimates of uncertainty for photon dose in Hanford non-plutonium facilities. 

Dosimeter

Period of 

use

Bias magnitude and range Uncertainty factors

Overall biasa Range in biasb Systematicc Randomd

Non-plutonium facilities

Two-element film 1944–57 1.27 1.23-1.60 1.2 1.8

Multielement film 1958–71 1.02 0.86-1.12 1.1 1.4
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 56 of 91

Hanford TLD 1972–83 1.12 1.04-1.16 1.05 1.2

Hanford TLD 1984-94 1.01 0.95-1.05 1.05 1.2

Commercial TLDe 1995–2003 1.00 0.95-1.05 1.05 1.2

a. Based on the distribution of energy levels and geometry judged most likely. Divide recorded dose by the table's bias 

value to calculate Hp(10) dose.

b. Range of overall bias factors based on alternative distributions of energy levels and geometry.

c. Systematic uncertainty resulting from lack of knowledge regarding actual distributions of energy levels and geometry.

d. Random uncertainty resulting from variation among workers in energy levels and geometry.

e. Performance equal to or better than previous Hanford dosimeter.

Uncertainty in the positive recorded photon dose for Hanford workers in the low-energy photon fields 

characteristic of plutonium facilities is certainly larger than the values shown in Table 6-32. An 

estimate of the overall bias (defined as the ratio of the deep dose to the recorded whole body dose) is 

provided by Wilson et al. (1990) for the respective Hanford dosimeter types according to major facility 

categories as shown in Table 6-33. 

The Hanford film and thermoluminescent dosimeters easily respond to the predominant 17 keV 

(plutonium X-rays) and 60 keV (241Am) photon radiation, particularly if the non-penetrating and 

penetrating whole body and extremity dose components are analyzed (i.e., as shown in Figure 6-17) 

as was routine practice at Hanford. The ratio of the non-penetrating and penetrating dose was 

routinely used in the analysis of dose (Larson and Roesch 1954). However, the variation in the 

recorded dose is highly effected by shielding, the worker’s orientation in the field, etc. Evaluations of 

the dosimetry for Hanford plutonium workers have received more examination historically than any 

other area as shown by the letters, references, and bibliography noted in Wilson et al. (1990). In the 

early years, contamination of the plutonium by fission and activation problems undoubtedly occurred, 

which likely increased the energy of the radiation. DOELAP testing formally began in 1986 (DOE 

1986) and included a 17 keV (k-fluorescent X-ray characteristic of plutonium) and 60 keV (241Am) 

beams. 

 Table 6-33. Estimate of Overall Photon and Neutron Radiation Bias Factor. 

Bias Factora

Dosimeter Period

Fuel 

Fabrication Reactor

Fuel 

Reprocessing

Plutonium 

Finishing

Waste & 

Laboratory

Min Max Min Max Min Max Min Max Min Max

Two-Element 

Film

1944-

1957

0.5 1.6 0.5 1.7 0.5 1.6 (b) (b) 0.5 1.6

Multi-Element 

Film

1958-

1971

0.7 1.3 0.7 1.4 0.7 1.3 1.0 2.0 0.7 1.3

TLD 1972- 

1989

0.8 1.2 0.8 1.2 0.7 1.3 0.6 1.4 0.8 1.2

a. The bias factor is defined as the ratio of the deep dose to the recorded whole body dose. 

b. Recorded photon and neutron dose known to be in error. Photon dose could be based on open window response of 

film dosimeter and neutron dose based on neutron to photon dose ratio of 1:1 (Wilson et al. 1990).

6.7.3

The technical inadequacy to measure the neutron dose with NTA film at Hanford prior to 1972 is well 

known. As such, the recommended option is to utilize a neutron to photon dose ratio. The 

uncertainty in this approach is a combination of the neutron to photon dose uncertainty and the 

uncertainty of the measured photon dose. 

Neutron Dose

With the TL dosimeter methods beginning in 1972, comparisons of the Hanford thermoluminescent 

dosimeter photon and neutron dose measurements at the Hanford plutonium facilities have been 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 57 of 91

conducted on several occasions with TEPCs and, in fact, the neutron dose calibration of Hanford 

TLDs is based on field measurements at the Hanford 234-5Z facility. The Hanford TLD and TEPC 

measurements compare on average (i.e., no change in dosimeter algorithm recommended), however 

the variability is significant. A factor of 3 difference in closely placed dosimeters for a single many 

hour measurement is often observed. 

6.8 ANALYSIS OF CLAIMS FILED BY HANFORD WORKERS

An analysis of external dose parameters reported in Hanford claims was done to better determine 

dose reconstruction recommendations. There are three primary sources of information in each claim 

that provide information of interest used to reconstruct external dose: (1) U.S. Department of Labor 

(DOL) claim documentation; (2) DOE medical X-ray, dosimetry, and incident archive records; and (3) 

records of interviews with claimant and coworkers, as available. This information is used to identify 

the employment period, job title and work activities, coworkers, supervisors, etc., for use in dose 

reconstruction. Analysis of the historical radiation monitoring and dose documentation for the 

respective claims provides insight into Hanford dosimetry practices, such as assignment of 

dosimeters, exchange periods, and dose recording levels. 

For purposes of dose reconstruction, it is recognized that while “average” and “routine” activities are 

important and probably represent most exposure scenarios, there could be unusual circumstances in 

some claims that require special evaluation.

6.8.1

There were a total of 7,234 annual dose records for 2,495 claims filed with the DOL with positive 

reported external dose as of September 15, 2006. Doses for these claims were analyzed to examine 

trends in the data. These claims were assembled in a database with one record of annual dose data 

for each year of employment for each claimant. Overall, a total of 49,897 dose records were 

assembled for Hanford worker claims. The average period of employment for claimants was 10.9

years, the maximum was 48.9 years (~1949 to ~1997), and the distribution of the number of claims by 

years of employment is shown in Table 6-34. Figure 6-18 illustrates the frequency of the archive 

doses available for the 2,495 claims in each of the respective years. As would be expected, the very 

early years have relatively fewer dose records. 

Years with a Claim

 Table 6-34. Frequency of claims according to 

 duration of Hanford employment. 

Hanford Employment 

(years) Number of claims

<1 362

1-2 201

2-3 150

3-4 100

4-5 102

5-10 490

10-20 725

20-30 202

30-40 148

40-50 15

Total No. of claims 2,495
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 58 of 91

Number of Hanford claims

0

100

200

300

400

500

600

700

800

900

1000

1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Number of active claims with positive 

archive dose

 Figure 6-18. Frequency distribution of archive records for active Hanford claims within

 the respective years. 

6.8.2

Comparisons were made between the original measured penetrating dose (identified as archive 

hereafter) from penetrating photon radiation reported in Buschbom and Gilbert (1993) for years 1944 

through 1989 and the assigned penetrating photon dose used in dose reconstruction. A comparison 

of the average and maximum doses for each year are presented in Figure 6-19. For the years when 

the maximum archive dose is equal to the assigned dose (e.g. 1963, 1977, etc.), this indicates a claim 

has been filed for the Energy Employees (EE) with the maximum archive dose. For all years, the 

assigned average and maximum annual doses are very similar with the exception being years prior to 

about 1954 when it is evident that some workers with the maximum archive dose have either not filed 

a claim or their claim information is not yet available for analysis (i.e., as of September 15, 2006). It is 

important to understand that these doses represent a comparison of the archive and assigned 

measured external radiation dose based on the DOE radiological records. The total assigned organ 

dose is not shown in Figure 6-19 that results from various elements of the NIOSH dose reconstruction 

(NIOSH 2002) process used to calculate a favorable to the claimant organ dose and to account for 

potential unmeasured dose arising from potential unrecorded (i.e., missed dose) occupational dose 

from photon or neutron external radiation, ambient environmental dose, medical X-ray dose, and 

internal intakes. These typically result in a highly significant increase to the original measured dose. 

Analysis of Assigned Doses
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 59 of 91

10.0

100.0

1000.0

10000.0

100000.0

1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Annual Dose, mrem

Average of assigned dose

Maximum assigned dose

Average recorded dose

maximum recorded dose

 Figure 6-19. Comparison of average and maximum annual measured penetrating dose

 as originally recorded in Buschbom and Gilbert (1993) and as assigned in dose 

 reconstruction prior to inclusion of missed occupational (external and internal radiation), 

 medical X-ray, or ambient assigned dose. 

6.9 RECOMMENDATIONS FOR HANFORD WORKER EXTERNAL DOSE

RECONSTRUCTION 

Recommendations for dose reconstruction for Hanford workers is based on the foregoing information

and the objective to provide an analysis that is favorable to claimants. Potential sources of additional 

dose to be assigned to the EE include:

• Adjustments to recorded occupational dose. 

• Assignment of missed dose for monitored workers for low dose results (i.e., less than MDL/2 of 

the personnel dosimeter). 

• Assignment of unmeasured neutron dose to monitored and unmonitored workers. 

• Adjustments to measured and missed dose associated with glovebox work activities for some 

workers and use as appropriate of the special plutonium dose conversion factors. 

• Assignment of potential dose to unmonitored workers. 

6.9.1

Hanford worker-recorded dose measurements are considered reasonably accurate from 1944 through 

the present with exceptions as follows:

Adjustments to recorded occupational dose

• The low-energy photon dose component measured in Hanford plutonium facilities with the 

original two-element film dosimeter used prior to 1958 may be too low. Hanford practice was 

stated to include assignment to the penetrating dose of 20% of the measured non-penetrating 
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 60 of 91

dose in plutonium facilities only. However, clear confirmation that this was indeed done for all 

years has not been possible to date. As such, if the early photon dose is significant to the 

dose reconstruction, the dose reconstructor may select to adjust the penetrating dose by using 

20% of the nonpenetrating or shallow recorded dose to ensure a favorable assigned photon

dose. 

• Neutron doses determined prior 1/1/1972 with the NTA film dosimeter are likely too low and a 

neutron to photon dose ratio should be used to assign a favorable dose to the claimant. 

• Neutron dose measurements with the workplace performance-validated TLD implemented in 

1972 are considered accurate with the exception of a period from 1978 through 1983 when a 

4-chip Hanford TLD was used. The recorded neutron dose during this period was too low. A 

factor of 1.35 times the recorded neutron dose should be used to ensure a favorable assigned 

neutron dose.

• An adjustment in recorded or assigned neutron dose for all years is needed to incorporate 

ICRP Publication 60 neutron weighting factors. 

6.9.2

Missed dose occurs when the dose of record is zero because the dosimeter response was less than 

the MDL or there is no dose of record for an assigned badge for a monitoring period. This kind of 

missed dose is most important for earlier years when MDLs were higher and dosimeter exchange was 

more frequent. Dose reconstructors should follow NIOSH (2002) guidance and use data in Table 6-

35 to calculate the missed photon dose. The method recommended for estimating missed photon 

dose is to assign a missed photon dose based on the MDL/2 method and the number of exchange 

periods (NIOSH 2002) given in Table 6-35 for the respective dosimetry systems. 

Determination of Missed External Dose for Low-Dose Results for Monitored Workers

Table 6-35. Potential missed dose for low-dose values. 

Dosimeter Period

Exchange

frequencya 

MDL (mrem)

Missed annual 

mean dose (rem)

Skin Deep Neutron Skin Deep Neutron

Pocket ionization chamber Early 1940s Daily 5 5 N.A. 0.625 0.625 (d)

Hanford two-element βγ film 1944–1950 Weekly 40b 40b (c) 1.040 1.040 (d)

Hanford two-element βγ film 

and NTA film

1951–1957 Biweekly 40 40 (c) 0.520 0.520 (d)

Hanford two-element βγ film 

and NTA film

1958–1971 Monthly 40 40 (c) 0.240 0.240 (d)

Hanford TLD 1972-1994 Monthly 50 20 I 0.300 0.120

Hanford Commercial TLD 1995-present Monthly 30 10 I 240 0.060

a. Exchange frequencies were established from dosimetry reports for routine exchange. 

b. Estimated MDL typical of film dosimeter capabilities (Wilson 1960b, 1987; NRC 1989; Wilson et al. 1990).

c. The MDL for neutron doses estimated for years prior to 1972 was unreliable.

d. For years prior to 1972, the reconstructed neutron dose is calculated using the adjusted photon dose and a neutron-tophoton dose ratio.

6.9.3

Determination of the missed neutron dose for the period of NTA use prior to 1972 can be made using 

the values in Table 6-36. 

Determination of Missed Neutron Dose for Monitored and Unmonitored Workers
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 61 of 91

 Table 6-36. Potential missed neutron dose. 

Facility

Neutron to Photon Dose Ratio

GM GSD 95th

Once through reactors: 100B, 100F, 100C, 100D, 

100DR, 100KE, 100KW, and 100H 

0.41 2.79 2.22

N-Reactor 0.06 3 0.37

FFTF (a) (a) (a)

Plutonium Facilities 0.73 2.1 2.47

All others 0 0 0

a. FFTF operated only while TLND used to measured neutron dose.

The period of missed neutron dose with the Hanford TLD during 1978 through 1983 can be made 

using:

 Assigned neutron dose = recorded neutron dose * 1.35

6.9.4

Guidance in OCAS-TIB-0010 (NIOSH 2005) should be used to adjust the measured photon dose to 

Hanford workers in identified Hanford plutonium facilities.

Adjustment for Glovebox Workers

6.9.5

For unmonitored Hanford workers, coworker doses from photon radiation for Hanford are presented in 

ORAUT-OTIB-0030 (ORAUT 2005b). This reference should be used to assign unmeasured photon 

radiation dose to Hanford workers. Typically, all significantly exposed Hanford workers should have 

been monitored with a recorded dose. 

Unmonitored Worker External Dose

There should not, typically, be a significant neutron exposure to unmonitored workers. However, for 

an unmonitored worker with some evidence of potential neutron exposure, neutron doses can be 

conservatively estimated from the median photon doses for radiation workers listed in Table 6-36 by

applying the median neutron-to-photon dose ratio (GM) listed for the respective facilities. Multiplying 

the median neutron-to-photon dose times the appropriate co-worker photon dose (50th or 95th

percentile) for Hanford radiation workers for each year will yield a favorable to claimant assigned 

neutron dose to unmonitored workers. 

6.9.6

Hanford practice to assign the skin dose was to include the nonpenetrating and penetrating dose 

components as summarized in Table 6-37. Additional guidance on determining skin dose can be 

obtained from ORAUT-OTIB-0017, Interpretation of Dosimetry Data for Assignment of Shallow Dose

ORAUT 2005a).

Skin Dose

Table 6-37. Historical Hanford recorded dose practices. 

Year Dosimeter measured quantities Compliance dose quantities

Two-element beta/photon film dosimetera

1944-47 OW = Open Window, mrep

S = “Silver filter” dosimeter response, mR

Skin = OW + S

WB = S

1948-50 beta = Open Window, mrep

gamma = “Silver filter” dosimeter response, mR

Skin = beta + WB

WB = Gamma 

Two-element beta/photon film dosimeter + NTA neutron dosimeter

1950-57 beta = Open Window, mrep

gamma = “Silver filter” dosimeter response, mR

Skin = beta + WB

WB = Gamma + Neutron 

Multi-element beta/photon dosimeter + NTA neutron dosimeter
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 62 of 91

1957-58 Beta

Gamma

X-ray

Neutron

Skin = Beta + Gamma + 65% X-ray + 

Neutron

WB = Gamma + 0.35% X-ray + 

Neutron

1959-71 Beta (-B-)

Gamma (-G-) 

X-ray (-X-) 

Fast neutron (F-N)

Slow neutron (S-N)

Derma (skin) = Beta + WB + 65% Xray

WB (Penetrating) = Gamma + neutron 

+ 35% X-ray)

Thermoluminescent dosimeter

1972-94 Nonpenetrating (NPEN)

Penetrating (PEN)

Slow Neutron (SN)

Fast Neutron (FN)

Skin = NPEN + WB

WB= PEN + SN + FN

1995-2003 Shallow (Sh

Deep (Dp)

Neutron (Nt)

Skin = Sh + Dp + Nt

WB = Dp + Nt

a. From 1948-56, when dosimeter quantities for each period were noted as beta or gamma, the cumulative dosimeter dose 

quantities continued to be labeled as OW and S.

6.9.7

Ring extremity dosimeters have been assigned to Hanford radiation workers who directly handled 

plutonium or beta emitting nuclides with a significant potential to result in an extremity dose that was 

more limiting than the whole body dosimeter. A standard monitoring practice in operational health 

physics is to establish a factor between whole-body and extremity exposures to determine when 

extremity dosimeters should be assigned. The factor is typically based on radiation guidelines for the

extremity, skin, and whole body, which have varied over the years. At the 1949 meeting in Chalk 

River, Canada, among U.S., UK, and Canadian nuclear weapon development organizations, several 

aspects of operational health physics were defined (Taylor 1971). The identified limits were:

Extremity Dose

Whole body – 0.3 rem/wk; skin – 0.5 rem/wk and extremity 1.5 R/wk.

Based only on the limits, it would not be necessary to monitor the extremity dose unless it was greater 

than a factor of about 5 multiplied times the whole body dose, otherwise the whole body dose would 

be limiting. To make certain that instances did not arise where in fact, the extremity dose limit could 

be exceeded, typically a lower factor is adopted, such as a factor of 3. As such, based on this 

analysis, it is recommended that the measured whole body dose be increased by a factor of 3 as a 

favorable to claimant assumption to assign a dose to the extremities based on the premise that 

monitoring to the extremity would have been performed if this was significant at the higher dose level. 

6.9.8

Tables 6-13 and 6-17 summarize the recommended radiation dose fractions for Hanford dose 

according to facility, worker occupational classification, and energy categories required by IREP. 

Radiation Dose Fraction

These assumptions will generally result in favorable to claimant estimates of organ dose.

6.9.9

Once the adjusted doses have been calculated for each year, the values are used to calculate organ 

doses of interest using the external dose reconstruction implementation guidelines (NIOSH 2002). 

Wilson et al. (1990) states “workers are typically facing the work being done, and for routine radiation 

Organ Dose
Document No. ORAUT-TKBS-0006-6 Revision No. 02 Effective Date: 11/21/2006 Page 63 of 91

exposure over long time periods, the front of the torso can be expected to receive the largest 

cumulative exposure.” It is recommended that the 100% AP (front-to-back) geometry should be 

assumed for the irradiation geometry and for conversion to organ dose. The calculated neutron doses 

should be multiplied by the conversion factors from deep dose equivalent to organ dose for AP 

irradiation from Appendix B of NIOSH 2002. For photons prior to 1972 (film badge era), the 

conversion factor from exposure to organ dose should be used. For 1972 to the present (TLD era), 

the conversion factor from deep dose equivalent to organ dose should be used.

6.9.10

6.9.10.1 Minimizing Assumptions

Claim Analysis Methods

When a claim is categorized as likely compensable, minimizing assumptions to assign a dose to the 

EE are used to process the dose assessment quickly and simply. Assumptions such as assigning no 

neutron dose or no missed dose are typical minimizing assumptions that can expedite processing. If 

the assigned dose corresponds to a POC exceeding a value identified by OCAS (i.e., currently 52%), 

even with minimizing assumptions, the claim is probably compensable.

6.9.10.2 Maximizing Assumptions

When a claim is categorized as likely noncompensable, maximizing assumptions to assign a dose to 

the EE are used to expedite claim processing. Assigning the maximum neutron dose, maximum 

missed dose, and maximum adjustment for uncertainty are typical maximizing assumptions. If the 

assigned dose with maximizing assumptions corresponds to a POC less-than a value identified by 

OCAS (i.e., currently 45%), the claim is probably noncompensable.

6.9.10.3 Best Estimate Assumptions

The resolution of claims that require a more realistic assessment to determine compensability should 

consider that the conversion of photon and neutron doses of record to organ doses requires careful 

evaluation without simplifying assumptions. Best available data for the claimant should be used, 

including actual dosimeter results, actual number of X-rays, and actual uptakes. 

6.10 UNCERTAINTY IN PHOTON AND NEUTRON DOSES

For the usual analysis of measured film badge doses, MDLs in the literature range from about 30 to 

50 mrem for beta/photon irradiation (Wilson et al. 1990). It is possible to read a photon dose of 100 

mrem to within ±15 mrem if the exposure involved photons with energies between several keV and 

several MeV (Morgan 1961). The estimated standard error in recorded film badge doses from 

photons of any energy is ±30%. 

The situation for neutrons was not as favorable as for photons. With NTA films used at Hanford 

before 1972, the estimated standard error was larger and varied significantly with the energy of the 

neutrons. Therefore, measured neutron doses to workers were very likely underestimated. The 

recommended approach is to use neutron-to-photon dose ratios to estimate the neutron dose using 

the reliably measured photon doses. For TLDs used at Hanford beginning in 1972 through 1987, the 

estimated standard errors for photon and neutron dose, respectively, of 100 mrem or more are 

approximately ±30% and ±50% based on actual DOELAP performance testing or preparations for 

testing. 
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GLOSSARY

absorbed dose, D 

Amount of energy imparted by radiation to unit mass of absorbing material (100 ergs per 

gram), including tissue. The unit used prior to the use of the International System of metric 

units (SI) is the rad; the SI unit is the gray.

accreditation 

Recognition that a dosimeter system has passed the performance criteria of the DOE 

Laboratory Accreditation Program (DOELAP) standard (DOE 1986) in specified irradiation 

categories.

accuracy 

If a series of measurements has small systematic errors, they are said to have high accuracy. 

The accuracy is represented by the bias.

albedo dosimeter 

A TLD device that measures the thermal, intermediate and fast neutrons that are scattered 

and moderated by the body from an incident fast neutron flux.

algorithm 

A computational procedure.

Atomic Energy Commission

Original agency established for nuclear weapons and power production; a successor to the 

Manhattan Engineer District (MED) and a predecessor to the U.S. Department of Energy 

(DOE).

BF3 chamber or counter

Proportional counter using gaseous BF3 compound to detect slow neutrons through their 

interaction with boron.

backscatter 

Deflection of radiation by scattering processes through angles greater than 90 degrees, with 

respect to the original direction of motion.

beta particle 

A charged particle of very small mass emitted spontaneously from the nuclei of certain 

radioactive elements. Most (if not all) of the direct fission products emit (negative) beta 

particles. Physically, the beta particle is identical with an electron moving at high velocity.

Bonner Sphere

See Multi-Sphere neutron Spectrometer

calibration blank

A dosimeter that has not been exposed to a radiation source. The results from this dosimeter 

establish the dosimetry system base line or zero dose value.

collective dose equivalent

The sum of the dose equivalents of all individuals in an exposed population. Collective dose is 

expressed in units of person-rem (person-sievert).
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curie

A special unit of activity. One curie exactly equals 3.7 x 1010 nuclear transitions per second.

Cutie Pie (CP)

A portable ion chamber survey meter with a pistol grip and a large cylindrical ionization 

chamber.

deep absorbed dose (Dd)

The absorbed dose at the depth of 1.0 cm in a material of specified geometry and 

composition.

deep dose equivalent (Hd)

The dose equivalent at the respective depth of 1.0 cm in tissue.

Densitometer

Instrument that has a photocell to determine the degree of darkening of developed 

photographic film.

density reading

See optical density.

dose equivalent (H)

The product of the absorbed dose (D), the quality factor (Q), and any other modifying factors. 

The special unit is the rem. When D is expressed in Gy, H is in Sieverts (Sv). 

(1 Sv = 100 rem.)

DOELAP

The DOE Laboratory Accreditation Program (DOELAP) accredits DOE site dosimetry 

programs based on performance testing and onsite reviews performed on a two-year cycle.

dose equivalent index

For many years, the dose equivalent used to calibrate neutron sources that were used to 

calibrate neutron dosimeters a concept of summing the maximum dose equivalent delivered in 

the International Commission on Radiological Units (ICRU) sphere at any depth for the 

respective neutron energies even though the maximum dose occurred at different depths.

dosimeter

A device used to measure the quantity of radiation received. A holder with radiation-absorbing 

elements (filters) and an insert with radiation-sensitive elements packaged to provide a record 

of absorbed dose or dose equivalent received by an individual. (See albedo dosimeter, film 

dosimeter, neutron film dosimeter, thermoluminescent dosimeter.)

dosimetry system

A system used to assess dose equivalent from external radiation to the whole body, skin, 

and/or extremities. This includes the fabrication, assignment, and processing of the 

dosimeters as well as interpretation and documentation of the results.

DuPont 552

A film packet containing two pieces of film: (1) a 502 sensitive film and (2) a 510 insensitive 

film.
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DuPont 558

A film packet containing a 508 film with one side having a sensitive emulsion and the other 

side insensitive emulsion.

Eastman Kodak Nuclear Track Emulsion, Type A (NTA)

A film that is sensitive to fast neutrons. The developed image has tracks caused by neutrons 

that can be seen by using oil immersion and 1000X power microscope.

error

A term used to express the difference between the estimated and "true" value. Error may also 

be used to refer to the estimated uncertainty.

exchange period (frequency)

Time period (weekly, biweekly, monthly, quarterly, etc.) for routine exchange of dosimeters.

exposure

As used in the technical sense, exposure refers to a measure expressed in roentgens of the 

ionization produced by gamma (or X) rays in air. 

exposure-to-dose-equivalent conversion factor for photons (Cx)

The ratio of exposure in air to the dose equivalent at a specified depth in a material of 

specified geometry and composition. The Cx factors are a function of photon energy, material 

geometry (e.g., sphere, slab, or torso), and material composition (e.g., tissue-equivalent 

plastic, soft tissue ignoring trace elements, or soft tissue including trace elements).

extremity

That portion of the arm extending from and including the elbow through the fingertips, and that 

portion of the leg extending from and including the knee and patella through the tips of the 

toes.

fast Neutron

Neutron of energy between 10 keV and 10 MeV (NBS 1957).

favorable to claimant

This term refers to the process of estimation based on technical considerations of the 

parameters significant to dose such that the estimated dose is not underestimated.

field calibration

Dosimeter calibration based on radiation types, intensity and energies present in the work 

environment.

film

Generally means a "film packet" that contains one or more pieces of film in a light-tight 

wrapping. The film when developed has an image caused by radiation that can be measured 

using an optical densitometer. (See Dupont 552, Dupont 558, Eastman Kodak, Nuclear 

Emulsions.)

film density

See optical density.
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film dosimeter

A small packet of film within a holder that attaches to a worker.

filter

Material used to adjust radiation response of a dosimeter to provide an improved tissue 

equivalent or dose response.

First Collision Dose

The “first collision dose” can be determined for either photons or neutrons. For neutron 

radiation, perhaps the simplest calculation that can be made is one relating dose to flux 

through a thin layer of tissue. The resulting graph, sometimes referred to as the first-collision 

curve, is derived from the assumption that the probability of two or more interactions per 

neutron is negligible (Hine and Brownell 1956). Because of the short range of the charged 

secondary radiation from fast neutrons, the first collision dose in irradiated material is 

practically the same as the absorbed dose (NBS 1961).

free-field dose equivalent

The dose equivalent assigned for neutron irradiation as if it were performed in free space with 

no background from air and room scattering and no source asymmetry (Schwartz and 

Eisenhauer 1982).

gamma rays

Electromagnetic radiation (photons) originating in atomic nuclei and accompanying many 

nuclear reactions (e.g., fission, radioactive decay, and neutron capture). Physically, gamma 

rays are identical to X-rays of high energy, the only essential difference being that X-rays do 

not originate in the nucleus. 

Geiger-Mueller (GM) counter 

A radiation measuring device used to detect beta and gamma radiation.

glove box

A device used in handling of quantities of radioactive isotopes to provide containment of the 

radioactivity and to avoid contamination of the hands.

gray (Gy)

The SI unit of absorbed dose (1 Gy = 100 rad).

3He Spectrometer

An instrument used to measure neutron energy spectra based on neutron interactions with 

3

He atoms to produce a triton and a proton that are detected in a proportional counter.

induced radioactivity

Radioactivity produced in certain materials as a result of nuclear reactions particularly the 

capture of neutrons.

Intermediate Energy Neutron

Neutron of energy between 0.5 ev (assumed to be 0.4 ev because of cadmium cutoff in 

neutron response) and 10 keV (NBS 1957).
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ionizing radiation

Electromagnetic radiation (consisting of photons) or particulate radiation (consisting of 

electrons, neutrons, protons, etc.) capable of producing charged particles through interactions 

with matter.

isotopes

Forms of the same element having identical chemical properties but differing in their atomic 

masses. Isotopes of a given element all have the same number or protons in the nucleus but 

different numbers of neutrons. Some isotopes of an element may be radioactive.

kilo-electron volt (keV)

An amount of energy equal to 1,000 electron volts.

luminescence

The emission of light from a material as a result of some excitation.

Manhattan Engineer District (MED)

U.S. agency designated to develop nuclear weapons and a predecessor to the U.S. 

Department of Energy (DOE).

Minimum Detection Level, MDL

The term minimum detection level is often confused because the statistical parameters 

necessary to its calculation are not explicitly defined. Nonetheless, it is often assumed to be 

the level at which a dose is detected at the two-sigma level (i.e., 95% of the time). The MDL 

should not be confused with the minimum recorded dose. 

minimum recorded dose

Based on a policy decision, the minimum dose level that is routinely recorded. A closely 

related concept is the dose recording interval. Hanford has generally recorded minimum 

doses of 10 mrem and at intervals of 10 mrem (i.e., 10, 20, 30, etc.).

million-electron volt (MeV)

An amount of energy equal to 1,000,000 electron volts.

Multiple-Collision Neutron Dose

The “multiple collision dose” for neutron radiation relates the dose to flux through tissue based 

on the assumption that two or more interactions per neutron occurs resulting in greater energy 

deposition. 

Multi-Sphere Neutron Spectrometer

The multi-sphere neutron spectrometer consists of a series of neutron moderating spheres of 

tissue equivalent material with a neutron detector positioned at the middle of the respective 

spheres. Algorithms are used to unfold the data to calculate the neutron spectra.

nuclear emulsion

Generally refers to NTA film.

neutron

A basic particle that is electrically neutral weighing nearly the same as the hydrogen atom.
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neutron, fast

Neutrons with energy equal or greater than 10 keV.

neutron, intermediate

Neutrons with energy between 0.4 eV and 10 keV.

neutron, thermal

Strictly, neutrons in thermal equilibrium with surroundings. Generally, neutrons with energy 

less than the cadmium cutoff at about 0.4 eV.

neutron–to-photon dose ratio 

In this TBD, this term refers to a neutron to photon dose ratio that is used with the photon 

fraction to estimate the unmeasured neutron dose.

neutron film dosimeter

A film dosimeter that contains an Eastman-Kodak Neutron Track Emulsion, type A, film 

packet.

nonpenetrating dose

Designation (i.e., NP or NPen) on Hanford film dosimeter reports that implies a radiation dose, 

typically to the skin of whole body, from beta and lower energy photon radiation.

open window (OW)

Designation on Hanford film dosimeter reports for nonpenetrating dose based on film 

response in this region with little (i.e., no metallic filter, only security credential) shielding. 

operating area

Designation of Hanford major operational work areas among the respective fuel fabrication 

(e.g., 300), reactor operations (e.g., 100B, 100C, 100D, 100DR, 100F, 100H, 100KE, 100KW, 

100N), chemical separations (e.g., U-Plant, T-Plant, B-Plant, UO3 Plant, Reduction 

Oxidization [REDOX] Plant and PUREX Plant) ), plutonium finishing (Z-plant), research and 

development (e.g. 300, 3000), and transportation, communication and general site support 

(e.g., 600, 700, 1100).

optical density

The quantitative measurement of photographic blackening the density defined as D = Log10

(Io/I).

pencil dosimeters

A type of ionization chamber used by personnel to measure radiation dose. These results 

may be labeled as “Pen” dose. Other names: pencil, pocket dosimeter, pocket pencil, pocket 

ionization chamber (PIC).

penetrating dose

Designation (i.e., P or Pen) on Hanford film dosimeter reports that implies a radiation dose, 

typically to the whole body, from higher energy photon radiation.

PuF4 source

A neutron source with plutonium tetrafluoride activating material. The source was used to 

duplicate the neutron energies in Hanford's plutonium facilities generally referred to as the 200 

Area Z-Plant or plutonium finishing plant.
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Personal Dose Equivalent, Hp(d)

Radiation quantity recommended for use as the operational quantity to be recorded for 

radiological protection purposes by the International Commission on Radiological Units and 

Measurements (ICRU 1993). The Personal Dose Equivalent is represented by Hp(d), where d 

identifies the depth (in mm) and represents the point of reference for dose in tissue. For 

weakly penetrating radiation of significance to skin dose, d = 0.07 mm and is noted as 

Hp(0.07). For penetrating radiation of significance to “whole-body” dose, d = 10 mm and is 

noted as Hp(10). 

photon

A unit or "particle" of electromagnetic radiation consisting of X- and/or gamma rays. 

photon dose fraction

In this TBD, this term has been used to identify the fraction of the measured photon dose used 

to estimate the unmeasured neutron dose by multiply this fraction times the neutron to photon 

dose ratio.

precision

If a series of measurements has small random errors, the measurements are said to have high 

precision. The precision is represented by the standard deviation.

quality factor, Q

A modifying factor used to derive dose equivalent from absorbed dose.

rad

A unit of absorbed dose equal to the absorption of 100 ergs per gram of absorbing material, 

such as body tissue.

radiation

One or more of beta, neutron, and photon radiation. 

radiation monitoring

Routine measurements and the estimation of the dose equivalent for the purpose of 

determining and controlling the dose received by workers.

radioactivity

The spontaneous emission of radiation, generally alpha or beta particles, gamma rays, and 

neutrons from unstable nuclei

random errors

When a given measurement is repeated the resulting values, in general, do not agree exactly. 

The causes of the disagreement between the individual values must also be causes of their 

differing from the "true" value. Errors resulting from these causes are called random errors.

RBE 

A ratio of the absorbed dose of a reference radiation to the absorbed dose of a test radiation 

producing the same biological effects, other conditions being equal.

rem

The rem is a unit of dose equivalent, which is equal to the product of the number of rads 

absorbed and the "quality factor."
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Roentgen

A unit of exposure to gamma (or X-ray) radiation. It is defined precisely as the quantity of 

gamma (or X) rays that will produce a total charge of 2.58 x 10-4 coulomb in 1 kg of dry air. An 

exposure of 1 R is approximately equivalent to an absorbed dose of 1 rad in soft tissue.

scattering

The diversion of radiation from its original path as a result of interactions with atoms between 

the source of the radiations and a point at some distance away. Scattered radiations are 

typically changed in direction and of lower energy than the original radiation.

shallow absorbed dose (Ds)

The absorbed dose at a depth of 0.07 mm in a material of specified geometry and 

composition.

shallow dose equivalent (Hs)

Dose equivalent at a depth of 0.07 mm in tissue.

shielding

Any material or obstruction that absorbs (or attenuates) radiation and thus tends to protect 

personnel or materials from radiation.

Sievert (Sv)

The SI unit for dose equivalent (1 Sv = 100 rem).

sigma pile

A device used to obtain thermal neutrons for calibration purposes.

silver shield(s)

The 1-mm- and 0.13-μm-thick shields covering the film packet in the early Hanford personnel 

film dosimeters.

skin dose

Absorbed dose at a tissue depth of 7 mg/cm2

. 

Snoopy

A portable neutron monitoring instrument with a moderated BF3 detector.

systematic errors

When a given measurement is repeated and the resulting values all differ from the "true" value 

by the same amount, the errors are called systematic.

thermal neutron

Strictly, neutrons in thermal equilibrium with surroundings. Generally, refers to neutrons of 

energy less-than the cadmium cutoff of about 0.4 ev.

tissue equivalent

This term is used to imply that the radiation response characteristics of the material being 

irradiated are equivalent to tissue. Achieving a tissue equivalent response is typically an 

important consideration in the design and fabrication of radiation measuring instruments and 

dosimeters.
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Tissue Equivalent Proportional Counter (TEPC)

This device is used to measure the absorbed dose from neutron radiation in near tissue 

equivalent materials and, through analysis of the counter data, determination of the effective 

quality factor and the dose equivalent.

TLD chip

A small block or crystal made of LiF used in the TLD.

TLD-600 - A TLD chip made from Li-6 (>95%) used to detect neutrons.

TLD-700 - A TLD chip made from Li-7 (>99.9%) used to detect photon and beta radiation.

thermoluminescent

Property of a material that causes it to emit light as a result of being excited by heat.

thermoluminescent dosimeter (TLD)

A holder containing solid chips of material that when heated will release the stored energy as 

light. The measurement of this light provides a measurement of absorbed dose. The solid 

chips are sometimes called crystals.

whole body dose

Commonly defined as the absorbed dose at a tissue depth of 1.0 cm (1000 mg/cm2

); however, 

this term is also used to refer to the dose recorded.

X-ray

Ionizing electromagnetic radiation of extranuclear origin.

Z-Plant

A Hanford facility, composed of several buildings, where plutonium is processed (also known 

as 234-5-Z Building). 
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Page 1 of 12 

TABLE OF CONTENTS

SECTION TITLE

A.0 Distribution Parameters..........................................................................................................

PAGE

81

A.1 Years of Exposure..................................................................................................................81

A.2 Rate .......................................................................................................................................81

A.3 Radiation Type.......................................................................................................................81

A.3.1 Beta/Photon.............................................................................................................81

A.3.2 Neutron....................................................................................................................83

A.4 Distribution Parameters.......................................................................................................... 84

A.4.1 Type ........................................................................................................................84

A.4.2 Parameter 1.............................................................................................................84

A.4.2.1 Resolution of Recorded Dose Components............................................ 84

A.4.2.2 Adjustments to Recorded Penetrating Dose........................................... 85

A.4.2.3 Adjustments to Recorded Neutron Dose ................................................ 86

A.4.2.4 Unmonitored Photon Dose ..................................................................... 88

A.4.2.5 Missed Photon Dose .............................................................................. 88

A.4.2.6 Missed Neutron Dose............................................................................. 89

A.4.2.7 Organ Dose............................................................................................ 91

A.4.3 Parameter 2 .............................................................................................................91

A.4.3.1 Hanford Workplace Recorded Dose Uncertainty .................................... 91

LIST OF TABLES

TABLE TITLE PAGE

A-1 IREP dose parameter input screen ........................................................................................81

A-2 Selection of beta and photon radiation energies and percentages .........................................82

A-3 Hanford facility neutron radiation energies, percentages, and default neutron 

dose fractions International Commission on Radiological Protection (ICRP) 60 

correction factors ...................................................................................................................84

A-4 Historical Hanford recorded dose practices............................................................................86

A-5 Hanford neutron-to-photon dose ratios...................................................................................87

A-6 Missed photon dose adjustments to recorded deep dose.......................................................88

A-7 Hanford neutron dosimeter period of use, type, MDL, exchange frequency, and 

potential annual missed dose................................................................................................. 89

A-8 Hanford Facility dose fractions and associated ICRP 60 correction factors ............................90
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A.0

Several technical parameters of the U.S. Department of Energy (DOE)-provided dose of record 

information are considered in the evaluation of individual claims. The focus of this attachment is to 

ensure a favorable to claimant analysis that considers the uncertainty in historically recorded dose. 

These doses are often based on less capable technology than currently available. A basis of 

comparison for evaluation of dose is the Personal Dose Equivalent, Hp(d), where d identifies the depth 

(in mm) and represents the point of reference for dose in tissue. For weakly penetrating radiation of 

significance to skin dose, d = 0.07 mm and is noted as Hp(0.07). For penetrating radiation of 

significance to “whole-body” dose, d = 10 mm and is noted as Hp(10). Hp(0.07) and Hp(10) are the 

radiation quantities recommended for use as the operational quantity to be recorded for radiological 

protection purposes by the International Commission on Radiological Units and Measurements 

(ICRU). These are the dose quantities used to accredit DOE dosimetry programs since the mid1980s. 

DISTRIBUTION PARAMETERS

The primary Interactive RadioEpidemiological Program (IREP) screen used to input dose parameters 

is in Table A-1. Input to these fields is obtained from the Hanford dose of record. The claim provides 

the primary organ of interest and other worker information needed to run IREP. Guidance for the 

selection of the parameters in Table A-1 by the dose reconstruction analyst is presented in the 

following sections.

Table A-1. IREP dose parameter input screen. 

Exposure

Radiation type

Distribution parameters

# Year Rate Type 1 2 3

1 1960 Acute Photon, 30-250 keV Normal 2 2 0

2 1961 Acute

A.1 YEARS OF EXPOSURE

The years of exposure should be identified from the claim information and from the DOE radiation 

dose reports. For years with no recorded radiation dose, a missed dose as described later in this 

section is calculated for all zero or missing records. Hanford policies required monitoring of all 

workers who entered a radiological control area and radiological monitoring staff were present in all 

primary facilities with the responsibility to ensure radiation protection guidelines were followed. Valid 

reasons are expected for years in which there is no recorded dose (i.e., a blank entry). 

A.2 RATE 

Acute is selected for all types of external beta and photon dose. Chronic is selected for neutron dose.

A.3 RADIATION TYPE

The evaluation is separated into beta/photon and neutron dose as described in the following sections.

A.3.1

Assumptions favorable to claimants should be made using guidance in Table A-2 for beta and photon 

radiation. The values presented in this table are intended to provide a favorable to claimant estimate 

Beta/Photon

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of parameters to be used to calculate the organ dose for long-term Hanford workers in the respective 

facilities.

Table A-2. Selection of beta and photon radiation energies and percentages.

Process/

buildings Description

Operations Radiation 

type

Energy 

Begin End selection, keV Percentage

Fuel 

fabrication

Produced reactor fuel and target assemblies from uranium. Beta

photon

> 15 

30–250 

100%

313, 306, 333 1945 1972 100%

Reactors

During operation: Highly dispersed fields of higher energy 

photon radiation fields from fission process, activation and fission 

product nuclides. Potentially narrow beams of higher energy 

neutron radiation from test ports, etc., into reactor core. Potential 

for significant airborne nuclides, and there might be significant 

higher energy beta radiation. 

Beta 

photon

> 15 

30–250 

> 250 

100%

25%

75%

Not in operation: Highly dispersed fields of higher energy 

photon radiation fields from activation and fission product 

nuclides. No significant neutron radiation. There might be 

significant higher energy beta radiation during maintenance work 

resulting from fission products.

B-Reactor 9/26/44 1946

1948 2/12/68

D-Reactor 12/17/44 6/26/67

F-Reactor 2/23//45 6/25/65

H-Reactor 10/29/49 4/21/65

DR-Reactor 10/50 12/31/6

4

C-Reactor 11/18/52 4/25/69

KW-Reactor 12/54 2/1/70

KE-Reactor 2/55 1/28/71

N-Reactor 12/63 1/6/87

B-Reactor 9/44 2/68

D-Reactor 12/44 6/6/67

FFTF 2/9/80 12/93

Processing 

plants 

Radiochemical operations: Highly dispersed fields of higher 

energy photon radiation fields from activation and fission product 

nuclides dominant to most exposure profiles. Potential for 

higher-energy beta radiation during sampling and maintenance 

work resulting from fission products. 

Beta 

photon

> 15 

30–250 

> 250

100%

25%

75%

T Plant 12/26/44 3/56

B Plant 4/13/45 1956

S Plant (Redox) 1/51 12/67

C Plant 7/52 7/67

A Plant (Purex) 1/56 6/72

1983 1988

U Plant 3/52 1/58

UO3 Plant 56

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Table A-2 (cont’d). Selection of beta and photon radiation energies and percentages. 

Process/

buildings Description

Operations Radiation 

type

Energy 

Begin End selection, keV Percentage

Plutonium 

production 

Plutonium component production: Plutonium is machined 

into weapon components using a glovebox assembly process 

with predominant close anterior exposure to workers. Radiation 

characteristics in this area involve significant lower energy 

photons and neutron radiation.

Photon < 30

30–250

25%

75%

Plutonium storage: Radiation characteristics in these areas 

generally involve dispersed lower energy scattered photons, 

including- 60 keV 241Am- gamma ray and neutron radiation.

200 Area PFP, Z-Plant, 234-5Z, 231-Z, 

etc.

1945 2003

300 Area Plutonium Laboratories 

308/309, 324

2003

Calibrations

Hanford site calibration of instruments 

and dosimeters Beta 

photon

> 15 

30 – 250 

> 250

100%

25%

3745-A, 318 1945 2003 75%

Waste 

handling

Radiation characteristics are highly dependent on source of 

waste, but typically fission product nuclides (Sr/Y-90, Cs-137) 

are dominant. 

Beta 

photon

> 15

30–250 

> 250

100%

50%

50% 200East and West 1953 2003

A.3.2

The circumstances of neutron exposure at Hanford facilities is based on the facility of worker primary 

employment and separated generally according to:

Neutron

1. 200 and 300 Area plutonium facilities where neutron radiation is generated from plutonium 

either by spontaneous fission or, importantly, by alpha particle interaction with light elements 

such as oxygen, fluorine and beryllium.

2. 100 and 400 Area reactor facilities where neutron radiation is generated by fission of uranium 

and plutonium in the reactor core. 

Potential neutron radiation in the 300 area facilities generally involved laboratory experiments related 

primarily to nuclear fuel development as well as neutron dose calibration of instruments and personnel 

dosimeters used throughout Hanford. These sources of neutron radiation exposure of workers should 

be evaluated according to the two general methods of neutron exposure (i.e., reactor or plutonium) 

that most closely fits the exposure pattern.

Simplified assumptions are presented in Table A-3 for neutron radiation. These values are intended 

to provide a favorable to claimant estimate of parameters to be used to calculate the organ dose for 

long-term Hanford workers in the respective facilities.

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Table A-3. Hanford facility neutron radiation energies, percentages, and default neutron dose 

fractions International Commission on Radiological Protection (ICRP) 60 correction factors. 

Process Description/buildings

Neutron 

energy

(MeV)

Default 

dose 

fraction

(%)

ICRP 60 

correctio

n factor

Reactors During Reactor Operation: Low level neutron exposure through shielding on the face of the 

reactors and through test ports. 

B, D, F, H, DR, C, KW, KE, N 0.1-2 

MeV 100% 1.91

FFTF 0.1-2 

MeV

2-20 

MeV

50%

50%

0.95

0.65

 Plutonium 

production

Plutonium Finishing Process: Plutonium enters the process as PuF4 and is then fired into 

production pucks. Work is primarily conducted in glove boxes with predominant close anterior 

exposure to workers. Radiation levels at the beginning of the process are fairly constant while 

levels at end of process are closely related to production levels. 

Plutonium Facilities (200 Areas)

(224-T, 231-Z, 232-Z,, 234-5Z, 236-Z, 242-Z, 2736-Z, 271-

U)

0.1-2 

MeV

2-20

MeV

90%

10%

1.71

0.13

Plutonium Laboratories (300 Area) (308, 309, 324)

A.4 DISTRIBUTION PARAMETERS

The selection of the distribution parameters in Table A-1 is discussed in the following sections. 

A.4.1

The selection of a normal distribution for the type determines the definition of Parameters 1 and 2. 

For a normal distribution, Parameter 3 is not used.

Type

A.4.2

For a normal distribution, parameter 1 is the mean of the distribution of recorded dose for each year of 

monitoring. Before calculating this, it might be necessary to adjust the recorded dose to provide a 

favorable to claimant estimate of Hp(10) in accordance with information in the following sections.

Parameter 1

A.4.2.1 Resolution of Recorded Dose Components

Hanford radiation monitoring policies prior to the mid-1990s required workers to be assigned a 

dosimeter for any entry into a radiologically controlled area. Beta/photon personnel dosimeters were 

assigned to all personnel and, in some facilities, personnel were also assigned a neutron personnel 

dosimeter. All dosimeters were processed and the results recorded. For any missing dosimeter data, 

an investigation was conducted to assign a dose to the worker. As such, the recorded dose record 

should be complete. Any blank results (i.e., for neutron dosimeters) are expected to be represent 

situations where the worker did not enter a radiologically controlled area or the dosimeter (i.e., 

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neutron) was not used. Since the mid-1990s, dosimeters are assigned only to workers anticipated to 

exceed a whole body dose of 100 mrem/year.

There are three major changes in the format of Hanford dosimeter processing results corresponding 

to the major changes in dosimeter types. This is clarified as follows: 

• Before 1957 – This period is characterized by use of the two-element dosimeter with doses 

reported for the film response behind the open window (OW) and 1-mm silver filtration (S). 

The nonpenetrating dose is typically referred to OW on the processing forms, but it might be 

identified as beta. The penetrating dose is typically referred to as S (i.e., silver) on the 

processing forms but it might be identified as gamma. During this period, Hanford processing 

data were manually recorded. As such, these forms were updated each year to allow staff to 

directly record dosimeter results for each dosimeter exchange period and for each operating 

area. These forms were organized to allow the dosimeter results to be totaled to manually 

calculate and record the annual dose for each worker. In the latter 1950s, the annual dose 

data were transferred to the newly implemented Hanford radiological computer system. 

• 1957 through 1971 – This period is characterized by the use of multielement film dosimeters 

that included an X-ray component in addition to the beta and gamma identified doses. To 

calculate the whole-body dose, 35% of the X-ray dose was added to the gamma dose (plus 

any neutron dose). To calculate the skin dose, the X-ray dose was added to the gamma dose 

(plus any neutron dose). The tritium dose was added to the whole-body and skin dose 

components beginning in about 1964. During this period, the dose results were computerized 

providing easy to read summaries.

• 1972 to present – This period is characterized by the use of thermoluminescent dosimeters 

(TLDs) that measured the beta, photon, and neutron dose. For the Hanford Multipurpose 

Dosimeter (HMPD), the doses were typically referred to as nonpenetrating, penetrating, slow 

neutron, and fast neutron. Later, the Hp(d) dose quantities were used in DOE Laboratory 

Accreditation Program (DOELAP) performance testing. The whole-body dose was calculated 

as the sum of the penetrating [later Hp(10)], slow neutron and fast neutron doses. The skin 

dose was calculated as the sum of the nonpenetrating [later Hp(0.07)] plus the whole-body 

dose. Until about 1987, the tritium dose was also included in the whole-body and skin doses. 

A summary of the respective Hanford recorded dosimeter recorded quantities and the compliance 

skin and whole body dose quantities based on the foregoing are shown in Table A-4. 

A.4.2.2 Adjustments to Recorded Penetrating Dose

No adjustment in the recorded photon dose is recommended for multi-element or thermoluminescent 

dosimeter recorded penetrating or gamma dose with the exception of the penetrating dose (i.e., 

identified as S dose in the early years) recorded for the two-element film dosimeter used prior to April 

1957. For this dosimeter, the adjusted penetrating dose is calculated as follows:

Adjusted penetrating dose = penetrating dose (i.e., S) + (0.2 * nonpenetrating dose (i.e.,OW)

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The adjustment is to be applied only

Table A-4. Historical Hanford recorded dose practices. 

to workers in Hanford 200 Area plutonium facilities. Significant 

errors will occur if this adjustment is applied to nonplutonium facility exposure.

Year Dosimeter measured quantities Compliance dose quantities

Two-element beta/photon film dosimetera

1944-47 O W = Open Window, mrep

S = “Silver filter” dosimeter response, mR

Skin = OW + S

WB = S

1948-50 beta = Open Window, mrep

gamma = “Silver filter” dosimeter response, 

mR

Skin = beta + WB

WB = Gamma 

Two-element beta/photon film dosimeter + Nuclear Track, Type A emulsion (NTA) neutron dosimeter

1950-57 beta = Open Window, mrep

gamma = “Silver filter” dosimeter response, 

mR

Skin = beta + WB

WB = Gamma + Neutron 

Multi-element beta/photon dosimeter + NTA neutron dosimeter

1957-58 Beta

Gamma

X-ray

Neutron

Skin = Beta + Gamma + 65% X-ray + 

Neutron

WB = Gamma + 0.35% X-ray + Neutron

1959-71 Beta (-B-)

Gamma (-G-) 

X-ray (-X-) 

Fast neutron (F-N)

Slow neutron (S-N)

Derma (skin) = Beta + WB + 65% X-ray

WB (Penetrating) = Gamma + neutron + 35% 

X-ray)

Thermoluminescent dosimeter

1972-94 Nonpenetrating (NPEN)

Penetrating (PEN) 

Slow Neutron (SN)

Fast Neutron (FN)

Skin = NPEN + WB

WB= PEN + SN + FN

1995-2003 Shallow (Sh

Deep (Dp)

Neutron (Nt)

Skin = Sh + Dp + Nt

WB = Dp + Nt

a. From 1948-56, when dosimeter quantities for each period were noted as beta or gamma, the cumulative dosimeter dose 

quantities continued to be labeled as OW and S.

A.4.2.3 Adjustments to Recorded Neutron Dose

Studies have shown a significant potential for under-estimation of the neutron dose for Hanford 

workers exposed to neutron radiation prior to

Before 1972. The neutron dose recorded historically at Hanford prior to the January 1, 1972, 

implementation of the HMPD is not accurate and likely to be significantly under-estimated. The only 

option to arrive at a favorable to claimant estimate of neutron dose prior to 1972 is to utilize neutronimplementation of the HPMD on January 1, 1972. The 

vast majority of neutron dose to Hanford workers was received at the 200 West Area Plutonium 

Finishing Plant (PFP) facilities. There is potential for significant missed dose in Hanford 300 Area 

plutonium facilities (308, 309, 324). There is also evidence of missed neutron dose to workers in the 

Hanford 100 Area reactor facilities. There is potential missed dose in Hanford 300 Area accelerator 

(3754B) and calibrations (3745, 318) and 400 Area Fast Flux Test Reactor facilities. 

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to-photon dose ratios. Essentially, all Hanford radiological work areas that involved significant 

neutron radiation also had significant photon radiation that was reliably measured. 

To arrive at a favorable to claimant analysis, a neutron dose should be calculated in all Hanford 

facilities with any potential for neutron dose using a neutron-to-photon ratios listed in Table A-5. The 

photon dose should be adjusted for any missed dose before applying the neutron-to-photon ratio to 

estimate the neutron dose.

After 1971. Neutron dose measurements at Hanford after 1971 with the five-chip HMPD and 

Harshaw TLD provide reasonable agreement with published field measurements with one exception. 

The exception concerns use of the four-chip HMPD during the period of its use from July 1978 

through December 31, 1983 in Hanford 200 and 300 Area plutonium facilities only. During this

period, the adjusted neutron dose is calculated as follows:

Adjusted neutron dose = 1.35 * recorded neutron dose

Table A-5. Hanford neutron-to-photon dose ratios.

Process Description/buildings

Neutron to photon ratio

Geometric 

mean

(GM)

Geometric 

standard 

deviation (GSD)

Upper 

95th%

Reactors During Reactor Operation: Low level neutron exposure through shielding on the face of the reactors 

and through test ports. 

B, D, F, H, DR, C, KW, KE Reactors 0.41 2.79 2.23

N Reactor 0.06 3.00 0.37

FFTF 1 1 1

Plutonium 

production

Plutonium Finishing Process: Plutonium enters the process as PuF4 and is then fired into production 

pucks. Work is primarily conducted in glove boxes with predominant close anterior exposure to 

workers. Radiation levels at the beginning of the process are fairly constant while levels at end of 

process are closely related to production levels. 

Plutonium Facilities (200 Areas)

(224-T, 231-Z, 232-Z,, 234-5Z, 236-Z, 242-Z, 2736-

Z, 271-U) 0.73 2.10 2.47 

Plutonium Laboratories (300 Area)

(308, 309, 324)

ICRP 60 Equivalent Neutron Dose. Historically, Hanford incorporated the energy variation of the 

dose equivalent into the calibration methodology. As a result, the recorded dose equivalent (DER) is a 

combination of all neutron energies. To calculate the probability of causation, the recorded neutron 

dose must be separated into neutron energy groups. Table A-3 summarizes favorable to claimant

default neutron dose fractions by energy for work areas where field measurements of neutron spectra 

were performed and using the associated ICRP 60 correction factors. The neutron dose equivalent is 

calculated by multiplying the recorded neutron dose by the area-specific correction factors. For 

example, consider a 1,000-millirem recorded neutron dose by a worker at the PFP, the corrected 

neutron dose is 1,710 millirem from neutrons between 0.1-2.0 MeV estimated to represent 90% of the 

dose fraction (i.e., 1,000 * 1.71) and 130 millirem from neutrons with energy between 2 and 20 MeV 

estimated to represent 10% of the dose fraction (i.e., 1,000 * 0.13). Thus, the corrected neutron dose 

is a total of 1,840 millirem. These adjustments should be applied to measured dose, missed dose, 

and dose determined based on a neutron-to-photon ratio. 

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A.4.2.4 Unmonitored Photon Dose

Adjustments to the recorded annual dose can be made using dose results for coworkers or the 

recorded dose before and after the period of missed dose. These situations require careful 

examination since Hanford policy was to monitor all workers who entered a radiological controlled 

area, and to estimate and record the dose for any missing results. 

A.4.2.5 Missed Photon Dose

Missed photon dose for Hanford workers can occur where (1) there is no recorded dose because 

workers were not monitored or the dose is otherwise unavailable, and (2) a zero dose is recorded for 

the dosimeter systems for any dosimeter response less than the Minimum Detection Level (MDL). 

Estimates of the missed dose can be made using dose results for coworkers or using the recorded 

dose before and after the period of missed dose. However, these situations require careful 

examination. The missed dose for dosimeter results less than the MDL is particularly important for 

earlier years, when MDLs were higher and dosimeter exchange was more frequent. NIOSH (2002) 

describes options to calculate the missed dose. One option is to estimate a favorable to claimant

maximum potential missed dose where the MDL/2 is multiplied by the number of zero dose results. 

Table A-6 summarizes the potential missed photon dose adjustments according to year, 

facility/location, dosimeter type, and energy range.

Table A-6. Missed photon dose adjustments to recorded deep dose. 

Time period

Dosimeter

MDLb 

(rem)

Exchange 

frequency

Annual 

missed 

dose (rem)c Default year Period of usea

1944 Prior to October 1944 PIC 0.005 Daily (n=250) 0.625

1945–1950 October 1944 - December 

1950

Hanford two-element film 0.040 Weekly (n=52) 1.040

1951–1957 January 1951 - March 1957 0.040 Biweekly (n=26) 0.520

1957 April 1957 - May 1957 Hanford multi-element 

film

0.040 Biweekly (n=26) 0.520

1958–1971 May 1957 - December 1971 0.040 Monthly (n=12) 0.240

1972–1994 January 1972 – December 

1994

Hanford TLD 0.020 Monthly (n=12) 0.120

0.020 Quarterly (n=4) 0.040

1995–2005 January 1995 - 2005 (ongoing) Harshaw TLD 0.010 Monthly (n=12) 0.060

0.010 Quarterly (n=4) 0.020

a. For many years, Hanford workers had a dosimeter assigned to each operating area where they worked.

b. Estimated MDLs for each dosimeter technology in the workplace.

c. Annual missed dose calculated from OCAS-IG-001 (NIOSH 2002).

Year. Table A-6 summarizes the potential maximum missed photon dose according to year using the 

default year shown in column 1. 

Facility/Location. The potential missed photon dose for the respective Hanford facilities is similar 

and, as such, Table A-6 can be used based on the year. 

Dosimeter Type. The potential missed photon dose for the respective periods of use, dosimeter 

types, MDL, and the exchange frequency is included in Table A-6. 

Energy Range. An estimate of the missed photon dose by energy range is possible based on the 

type of facility and predominant radionuclides such as intermediate (>100 keV) energies for all 

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facilities handling activation and fission product nuclides, primarily lower energy (<100 keV) photons 

for plutonium facilities and for uranium fuel fabrication facilities. The recorded dose from the 

dosimeter response does not typically provide sufficient information to estimate discrete energy 

ranges. It is possible to examine the energy response characteristics of the respective multielement 

dosimeters, but this analysis does not recognize the substantial uncertainties present in the workplace 

associated with shielding, radiation scattering, and mixed radiation fields.

A.4.2.6 Missed Neutron Dose

Neutron radiation was present in the 100 Area reactors, 200 Area plutonium, 400 Area Fast Flux Test 

Reactor (FFTF), 300 Area accelerator (3754B), calibrations (3745A and 318 Buildings) calibration 

facilities. There is a potential for significant missed neutron dose only for workers in the 200 Area 

PFP facilities that separated and finished plutonium (i.e., 224-T, 231-Z, 232-Z,, 234-5Z, 236-Z, 242-Z, 

2736-Z, 271-U) for use in nuclear weapons and some potential for significant missed neutron dose in 

the 300 Area Building 308 Plutonium Fabrication Pilot Plant and at the Building 309 Plutonium 

Research Test Reactor. The missed dose is calculated using Table A-5 and the MDL information for 

the TLDs in Table A-7. Table A-7 summarizes the period of use for Hanford neutron dosimeters for 

plutonium and non-plutonium facilities.

Table A-7. Hanford neutron dosimeter period of use, type, MDL, exchange frequency, and potential 

annual missed dose. 

Period of use Dosimeter

Exchange 

frequency

MDL 

(rem)a

Max. annual 

missed dose 

(rem)b

October 1944 - December 1949 PICs with 10B enriched liners Dailyc (n=250) 0.010 1.300

January 1950 – December 1950 NTA Weekly (n=52) 0.080 2.100

January 1951 - March 1957 Biweekly (n=26) 0.080 1.000

April 1957 - May 1957 Biweekly (n=26) 0.080 1.000

May 1957 - December 1971 Monthly (n=12) 0.080 0.500

TLD Dosimeter

January 1972 – December 1994 HMPD Monthly 0.050 0.300

January 1995 - present Harshaw TLD Monthly 0.015 0.100

a. Estimated film dosimeter photon radiation detection levels before 1972 and neutron dosimeter MDLs after 1971.

b. Annual missed neutron dose calculated using: Prior to 1972, neutron to photon ratio after combining the recorded and missed photon 

dose. The actual maximum annual missed dose will be the product of two lognormal distributions. After 1971, the lognormal 

distribution from the neutron dosimeter using a geometric mean of (n * MDL/2) and an upper 95% confidence interval of (n * MDL), 

where n is the number of missing dosimeter results.

c. Dosimeter not routinely assigned. 

Year. The approach used to calculate the neutron missed dose can be divided into two periods. The 

first period is before 1972 where the neutron dose is estimated from the measured and missed,

respectively, photon dose using neutron-to-photon dose ratios. The second period is after 1971 using 

TLDs. 

Before 1972. There is essentially no recorded neutron dose prior to 1950 when 10B-lined PICs were 

used. Recorded neutron dose using the NTA film will likely underestimate significantly the actual 

neutron dose (Fix, Wilson, and Baumgartner 1997). 

Due to the uncertainty in whether an employee’s NTA badge would respond to the workplace neutron 

spectrum, using a ratio of the neutron-to-photon dose is a favorable to claimant option to reconstruct 

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an individual worker neutron dose. This is based on the fact that routine neutron exposure is 

essentially always accompanied with measurable photon exposure (Watson 1959). The approach is 

illustrated as:

Missed Neutron dose = missed photon dose * neutron/photon dose ratio

The 95th percentile neutron/photon dose ratio can be used to estimate the maximum missed neutron 

dose. 

After 1971. Neutron dose assessment with the five-chip HMPD provides reasonable agreement with 

published field measurements. The potential missed neutron dose for the MDL and exchange 

frequency using NIOSH (2002) guidance is shown in Table A-5 for this time period. 

Facility/Location. The potential missed neutron dose for the MDL and exchange frequency using 

NIOSH (2002) is shown in Table A-7. 

Dosimeter Type. The potential missed dose for neutron dosimeters is strongly dependent on the 

neutron radiation field characteristics of the different Hanford facilities. This is also included in Table 

A-7. 

Energy Range. An estimate of the missed neutron dose by energy range is possible based on the 

type of facility and predominant neutron energies measured during the respective field 

measurements. The recorded neutron dose from the HMPD and Harshaw commercial TLD response 

does not provide sufficient information to estimate discrete energy ranges. Favorable to claimant

defaults are proposed based on available workplace spectra measurements. The values are listed in 

Table A-8. Since spectra measurements were not available for the single-pass reactors, a favorable 

to claimant default value of 100% fission spectra neutrons is assumed. This assumption is the most 

favorable to claimants because the Radiation Effectiveness Factors in the probability of causation

(POC) calculation are the greatest for this energy range. 

Table A-8. Hanford Facility dose fractions and associated ICRP 60 correction factors. 

Process Description/Buildings

Neutron Energy

(MeV)

Default Dose 

Fraction

(%)

ICRP 60 

Correction 

Factor

Reactors During Reactor Operation: Low level neutron exposure through shielding on the face of the reactors and 

through test ports. 

B, D, F, H, DR, C, KW, KE, N 0.1-2 MeV 100% 1.91

FFTF 0.1-2 MeV

2-20 MeV

50%

50%

0.95

0.65

Plutonium 

production

Plutonium Finishing Process: Plutonium enters the process as PuF4 and is then fired into production 

pucks. Work is primarily conducted in glove boxes with predominant close anterior exposure to workers. 

Radiation levels at the beginning of the process are fairly constant while levels at end of process are 

closely related to production levels. 

Plutonium Facilities (200 Areas)

(224-T, 231-Z, 232-Z,, 234-5Z, 236-Z, 242-

Z, 2736-Z, 271-U)

0.1-2 MeV

2-20 MeV

90%

10%

1.71

0.13

Plutonium Laboratories (300 Area)

(308, 309, 324)

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A.4.2.7 Organ Dose 

Once the adjusted photon and neutron doses have been calculated for each year, the values are used 

to calculate the organ dose distribution for the primary organ of interest identified in the claim. The 

front of the worker’s torso is expected to have received the greatest cumulative exposure and thus the 

AP orientation is typically selected. A comparison of dose conversion factors for the respective 

exposure geometries for the organ of interest can be made to determine a realistic option to perform a 

favorable to the claimant analysis. 

A.4.3

Parameter 2 is the standard deviation of the normal distribution for the organ dose. The individual 

dose result for each dosimeter exchange period will be available to calculate the mean and standard 

deviation for each year. If it is not available, the adjusted organ dose can be used for each year and a 

default standard deviation value used for parameter 2.

Parameter 2

A.4.3.1 Hanford Workplace Recorded Dose Uncertainty

Uncertainty in the recorded dose is an important consideration in favorable to claimant analyses. The 

overall uncertainty depends on (1) administrative practices, (2) dosimetry technology, (3) calibration, 

and (4) workplace radiation fields. The potential effect of each of these parameters on the recorded 

dose is described in the proceeding sections. 

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