ORAU TEAM

Dose Reconstruction

Project for NIOSH

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

Page 1 of 13

Document Title:

Technical Information Bulletin in Support 

of INEEL Technical Basis Document 

Section 6: Reanalysis of Hankins MTR 

Bonner Sphere Surveys

Document Number: ORAUT-OTIB-0009

Revision: 01

Effective Date: 12/13/2006

Type of Document: OTIB

Supersedes: Revision 00

Subject Experts: Norman D. Rohrig and Stephen L. Bump 

Approval: Signature on File Approval Date: 11/21/2006

John M. Byrne, Document Owner

Concurrence: Signature on File Concurrence Date: 11/21/2006

Edward F. Maher, Task 5 Manager

Concurrence: Signature on File Concurrence Date: 12/01/2006

Kate Kimpan, Project Director

Approval: Brant A. Ulsh Signature on File for Approval Date: 12/13/2006

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-OTIB-0009 Revision No. 01 Effective Date: 12/13/2006 Page 2 of 13

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION 

NUMBER DESCRIPTION

03/17/2004 00 New Technical Information Bulletin in Support of INEEL Technical 

Basis Document Section 6: Reanalysis of Hankins MTR Bonner 

Sphere Surveys. First approved issue. Initiated by Norman D. 

Rohrig.

12/13/2006 01 Approved Revision 01 for biennial review. Adds Introduction with 

required language and a Purpose section. Per new document 

requirements, added a Table of Contents. 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. Initiated by Norman D. Rohrig. Training 

required: As determined by the Task Manager. Initiated by Norman 

D. Rohrig.
Document No. ORAUT-OTIB-0009 Revision No. 01 Effective Date: 12/13/2006 Page 3 of 13

TABLE OF CONTENTS

SECTION TITLE

ACRONYMS AND ABBREVIATIONS..................................................................................................

PAGE

4

1.0 INTRODUCTION .....................................................................................................................5

2.0 PURPOSE ...............................................................................................................................5

3.0 REANALYSIS OF HANKINS MTR BONNER SPHERE SURVEYS.......................................... 5

REFERENCES..................................................................................................................................13

LIST OF TABLES

TABLE TITLE

3-1 Data from Hankins (1961) and reanalyzed doses.....................................................................

PAGE

7

3-2 Data from Hankins (1961) with thermal neutron measurement and reanalyzed doses ............. 8

3-3 Ratio of neutron dose equivalent rates at MTR ...................................................................... 10

3-4 Distribution of MTR neutron dose equivalent among IREP energy groups, NTA

response, and ratio of equivalent dose to dose equivalent ..................................................... 11

LIST OF FIGURES

FIGURE TITLE

3-1 Energy response of Bonner spheres ........................................................................................

PAGE

6

3-2 Neutron dose equivalent conversion factor .............................................................................. 7

3-3 Sample MTR spectra from reanalyzing Hankins Bonner sphere measurements ...................... 8

3-4 Dennis and Loosemore detector known as the Rudolf at the INEEL with its energy 

response curve ........................................................................................................................9

3-5 MTR neutron field components ................................................................................................9

3-6 Correlation of fast neutron dose equivalent to gamma dose at MTR ...................................... 12

3-7 ICRP 74 ambient dose equivalent conversion factor .............................................................. 12
Document No. ORAUT-OTIB-0009 Revision No. 01 Effective Date: 12/13/2006 Page 4 of 13

ACRONYMS AND ABBREVIATIONS

cm centimeter

DE dose equivalent

DECF dose equivalent conversion factor

DOE U.S. Department of Energy

EBR Experimental Breeder Reactor

ETR Engineering Test Reactor

eV electron-volt

hr hour

in. inch

ICRP International Commission on Radiological Protection

INEEL Idaho National Engineering and Environmental Laboratory

IREP Interactive RadioEpidemiological Program

keV kiloelectron-volt, 1,000 electron-volts

MeV megavolt-electron, 1 million electron-volts

mm millimeter

mrem millirem

MTR Materials Test Reactor

NCRP National Council on Radiological Protection and Measurements

NIOSH National Institute for Occupational Safety and Health

nrem nanorem

NTA nuclear track emulsion, Type A

TIB technical information bulletin

U.S.C. United States Code

§ section or sections
Document No. ORAUT-OTIB-0009 Revision No. 01 Effective Date: 12/13/2006 Page 5 of 13

1.0

Technical information bulletins (TIBs) 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 at 

particular sites or categories of sites. They will be revised in the event additional relevant information 

is obtained. TIBs may be used to assist NIOSH staff in the completion of individual dose 

reconstructions.

INTRODUCTION

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 of 2000 [42 U.S.C. § 7384l(5) and (12)].

2.0

This TIB provides a reanalysis of early neutron measurements from the Materials Test Reactor (MTR) 

at the Idaho National Engineering and Environmental Laboratory (INEEL) using present-day results 

for detector sensitivity to provide neutron spectra results based on current knowledge. This TIB 

results in neutron spectra which then have a certain portion of dose equivalent with energy below the 

detection threshold for NTA film. The correction for undetected neutron dose is then applied to 

neutron dose both measured by NTA film badges and that which would be missed by the badges. For 

persons not exposed to neutrons, this TIB has no affect on their dose reconstruction.

PURPOSE

3.0

Dale Hankins made a series of neutron field measurements (Hankins 1961) with 2-, 3-, and 8-in.-

diameter Bonner spheres (or balls) around the INEEL Materials Test Reactor (MTR). The balls were 

covered with a cadmium shield, which eliminates thermal neutrons below 0.41 eV. These 25 

measurements were mostly around the MTR floor, but one was at Experimental Breeder 

Reactor (EBR)-I through 9 ft of concrete and three were at the Engineering Test Reactor (ETR). Six 

other measurements labeled A to F include a thermal neutron component determined from the 

difference between a bare and a cadmium covered detector.

REANALYSIS OF HANKINS MTR BONNER SPHERE SURVEYS

Since then, significant improvements have been made to understanding the responses of these 

detectors to neutrons of all energies and, in particular, intermediate neutrons. The Hankins data have 

been reanalyzed using detector responses calculated by Hertel and Davidson (1985) for 171 energy 

groups from thermal to 17.3 MeV, as shown in Figure 3-1. This figure shows a higher sensitivity for 

the 2-in. and 3-in. detectors at low energies as compared to Figure 2 in Hankins (1961). These 

calculated response curves are more complete than the ones available in 1961, particularly below 

100-keV neutron energy where monoenergetic neutron spectra are not available.

These calculated response matrices are for 4- by 4-mm lithium iodide detectors, whereas the Hankins 

data used 2- by 8-mm detectors. Hertel and Davidson (1985) also calculated responses for 0.5- by

0.5-in. detectors, which have a larger response by about a factor of the detector surface area. 

Because most reactions in the detector are on the detector surface, the calculated neutron fluences 

and resulting dose equivalents are reduced by roughly a factor of 2 for all detectors and energies to 

account for the different size detectors used by Hankins (1961). 

Limited determination of the energy spectrum can be made from three different measurements of 

neutron response and the additional requirement that the number of neutrons in any energy region
Document No. ORAUT-OTIB-0009 Revision No. 01 Effective Date: 12/13/2006 Page 6 of 13 

0.00

0.05

0.10

0.15

0.20

0.25

1.E-01 1.E+01 1.E+03 1.E+05 1.E+07

Energy (eV)

Response 4 x4 mm (count cm^2/neutron)

2.0 INCH 

3.0 INCH 

8.0 INCH 

Figure 3-1. Energy response of Bonner spheres.

cannot be negative. Following Hankins (1961), the fraction of the summed response in each of the 

three balls (2-, 3-, and 8-in.) is calculated for a fission spectrum, and a 1/E slowing down spectrum;

spectral components expected in the reactor. The 1/E spectrum was assumed to go up to 0.6 MeV 

and was divided into two sections at 10 keV. To fit the Hankins data, the fission spectrum of the form

(Knoll, p 21) was used above 0.6 MeV.

E T

e

E

E /

1 / 2

1 ( ) − φ = (3-1)

For a typical fission spectrum, the characteristic temperature T is about 1.3 MeV, which was used in 

these calculations. The measured detector responses were expressed as a linear combination of the 

three spectra (1/E: 0.4 eV to 10 keV, 1/E: 10 to 600 keV, and fission) and solved.

To determine the dose equivalent, one must multiply the fluence at each energy by the dose 

equivalent conversion factor (DECF) for that energy and add them (i.e., integrate). The official 

tabulations provide conversion factors at limited energy values. Ing and Makra (1978) provide a 

parameterization for dose equivalent with energy that we use here. Figure 3-2 compares this 

parameterization to Monte Carlo calculations reported in National Council on Radiological Protection 

and Measurements (NCRP) Report 38 (NCRP 1971) and by Auxier et al. (1968). 

Table 3-1 lists measured values from Hankins (1961) and the resulting reanalyzed dose equivalents 

from the three energy groups and their sum. Table 3-2 provides the same information for the six 
Document No. ORAUT-OTIB-0009 Revision No. 01 Effective Date: 12/13/2006 Page 7 of 13

 

 

0

1

10

100

1.E-7 1.E-5 1.E-3 1.E-1 1.E+1 1.E+3

Neutron Energy (MeV)

DECF (nrem cm^2)

IngMakra p11

Auxier

Based on NCRP 38

Figure 3-2. Neutron dose equivalent conversion factor

(nrem/cm2

).

Table 3-1. Data from Hankins (1961) and reanalyzed doses.

Locationb

Total 

cpma

% Total cpma Dose equivalent (mrem/hr)

2 in. 3 in. 8 in. 0.4 eV–10 keV 0.01–0.6 MeV Fission >0.4 eV

EBR-I 1 2,935.6 31.3 49.9 18.8 0.208 0.337 0.300 0.845

2 491.7 30.7 49.5 19.8 0.034 0.064 0.066 0.163

3 2,854.1 31 49.4 19.6 0.200 0.304 0.462 0.966

4 2,966.2 30.6 49.1 20.3 0.204 0.340 0.556 1.100

5 2,315.2 29.8 49.1 21.1 0.152 0.375 0.350 0.876

6 1,698.5 29.9 48.9 21.2 0.113 0.247 0.314 0.674

7 611.1 29.6 48.4 22 0.040 0.084 0.149 0.273

8 981.9 29.5 48.3 22.2 0.064 0.136 0.250 0.450

9 5,539 28.9 48.2 22.9 0.350 0.933 1.338 2.621

10 662.9 29.1 48.1 22.8 0.042 0.100 0.176 0.319

11 5,700.6 29.5 48 22.5 0.376 0.699 1.699 2.773

12 7,603.3 28.7 47.9 23.3 0.477 1.257 2.056 3.789

13 6,185.1 29.3 47.8 23 0.404 0.763 2.005 3.172

14 2,694.6 29.6 47.6 22.8 0.180 0.258 0.973 1.411

15 3,116.3 28.9 47.5 23.6 0.200 0.412 1.071 1.683

16 8,877.1 28.5 47.4 24.1 0.556 1.337 3.021 4.913

17 2,083.4 29 47.3 23.7 0.135 0.241 0.787 1.163

18 2,581.4 28.4 47.3 24.3 0.161 0.391 0.904 1.456

19 1,627.8 28.1 47.3 24.6 0.099 0.275 0.548 0.923

20 4,848.1 28.2 46.8 25 0.302 0.665 2.008 2.975

ETR 21 111.3 27.7 46.5 25.8 0.007 0.017 0.048 0.072

22 1,494.8 28.2 46.2 25.6 0.094 0.158 0.750 1.003

23 4,427.9 26.5 45.6 28 0.252 0.774 2.295 3.321

ETR 24 199.2 26 44.7 29.3 0.011 0.032 0.124 0.166

ETR 25 210.9 25 44 31.1 0.011 0.038 0.144 0.193

Total 4.672 10.236 22.393 37.300

a. cpm = counts per minute.

b. At MTR, unless otherwise noted.
Document No. ORAUT-OTIB-0009 Revision No. 01 Effective Date: 12/13/2006 Page 8 of 13

locations where Hankins provided thermal measurements. The thermal values are as reported by 

Hankins. Figure 3-3 shows the resulting neutron spectra for locations 3 and 23, which have higher 

doses and nearly the maximum low energy and fission components, respectively.

Table 3-2. Data from Hankins (1961) with thermal neutron measurement and reanalyzed doses.

Location

cpm Dose equivalent (mrem/hr)

2 in. 3 in. 8 in. Thermal 0.4 eV–10 keV 0.01–0.6 MeV Fission Neutron

A 877 1,473 700 0.11 0.19 0.56 0.67 1.42

B 196 317 153 0.02 0.04 0.07 0.24 0.35

C 778 1,293 647 0.09 0.17 0.41 0.87 1.46

D 3,518 5,973 3,108 0.32 0.76 2.33 3.94 7.03

E 3,482 5,734 3,064 0.21 0.77 1.50 5.36 7.64

F 557 925 470 0.06 0.12 0.29 0.67 1.08

10

100

1000

10000

100000

1.E-01 1.E+01 1.E+03 1.E+05 1.E+07

Energy (eV)

Number Neutrons

Position 23

Position 3

Figure 3-3. Sample MTR spectra from reanalyzing 

Hankins Bonner sphere measurements.

Another survey at the MTR measured the fast neutron field (Sommers 1959a) using a Rudolf counter 

described as “a dose rate instrument, sensitive to neutrons in the range of 0.2 to above 10 MeV” 

(Sommers 1959b). This has been remembered as a detector about the size of a soda can with the 

end painted red. The Dennis and Loosemore (1961) detector shown in Figure 3-4 is believed to be 

what was known as the Rudolf counter at the INEEL. It detects hydrogen recoils and has a threshold 

energy of about 0.2 MeV. Using 0.2 MeV as the division line between fast and intermediate neutrons 

to correspond to that for this instrument, Figure 3-5 shows the correlation of the recalculated 0.4-eV to

10-keV and 10- to 200-keV neutron dose equivalent rates with the recalculated fast neutron dose 

equivalent rates along with the correlation of the Hankins analysis intermediate to fast neutron dose 

equivalents. Also shown are the Hankins thermal dose equivalent rates compared to the recalculated 

fast neutron dose equivalent rate. 
Document No. ORAUT-OTIB-0009 Revision No. 01 Effective Date: 12/13/2006 Page 9 of 13

Figure 3-4. Dennis and Loosemore detector known as 

the Rudolf at the INEEL with its energy response 

curve.

 

y = 4.633x

R2

 = 0.501

y = 0.046x

R2

 = 0.715 y = 0.140x

R2

 = 0.918

y = 0.131x

R2

 = 0.860

0.01

0.1

1

10

100

0.01 0.1 1 10

Fast Neutron Dose Equivalent Rate (mrem/hr)

Dose Equivalent Rate (mrem/hr)

InterHankins

Inter .5 eV-10 keV

Inter 10-200 keV

ThermalNeut

Figure 3-5. MTR neutron field components.
Document No. ORAUT-OTIB-0009 Revision No. 01 Effective Date: 12/13/2006 Page 10 of 13

The R2 values shown on the trend lines are the fractions of the variance, which is explained by the 

lines. For the reanalyzed data the R2 values are 92% and 86% compared to only 50% for the original

Hankins analysis, demonstrating that the reanalysis is a better fit. The slope of the trend lines is a 

dose weighted average of the ratios for the various data points. Table 3-3 provides comparisons of 

the different components of the neutron dose equivalent rate.

Table 3-3. Ratio of neutron dose equivalent rates at MTR.

Thermal

fast 0.4 eV–10 keV fast 10–200 keV fast

Total

fast

Trend line 0.046 0.140 0.131

Average 0.071 0.175 0.147 1.393

Minimum 0.033 0.066 0.073 1.226

Maximum 0.108 0.408 0.259 1.738

St dev 0.025 0.074 0.050 0.121

The Interactive RadioEpidemiological Program (IREP), which calculates the probability of causation1

The nuclear track emulsion, Type A (NTA) neutron dosimeters in use when the MTR was operating at 

the INEEL respond only to neutrons above 0.5 to 0.8 MeV. For the MTR spectra, Table 3-4 lists the 

fraction of neutron dose equivalent above 0.8 MeV, which would be picked up by the NTA film and 

which varies from 35% to 66%, depending on the location, with a mean of 0.52 and a standard 

deviation of 0.08. The remainder of these low-energy neutron fields would probably not be detected 

by the NTA film because of its 0.8-MeV threshold. To correct for missed dose on the MTR experiment 

floor, the NTA results from MTR should be multiplied by 2 ± 0.3 (1/0.52, 0.08/0.522

) for a Monte Carlo 

dose reconstruction.

, 

uses certain neutron energy groups. The dose equivalent rate and the fraction of the dose equivalent 

in each of these regions are listed in Table 3-4. For the numbered locations where no thermal 

neutron value is available, the average value for the ratio of thermal to fast of 0.71 from Table 3-3 is 

assumed.

Sommers (1962) reported thermal and fast neutron dose equivalent rates and gamma dose rates 

around the MTR beam lines. The thermal measurements near beams are believed to not be 

representative of the workplace. Figure 3-6 shows the correlation of fast neutron dose equivalent to 

the gamma dose for these measurements. The fast neutron component was insignificant for several 

of the measurements. These points are shown by the triangles at 0.5 mrem/hr, which is one-half of 

the smallest measured value. Including all the data in a Shapiro and Wilk W test for normality (Gilbert 

1987) gives a slightly better result for a normal distribution rather than a lognormal distribution. The 

fast neutron dose is 0.419 ±0.347 times the gamma dose. Combining these results with those of 

Table 3-3, one can conclude that the ratio of total neutron dose equivalent to gamma dose is 

0.58 ±0.48 at the 1-sigma level. The variation on the relative neutron components are buried by the 

fast neutron to gamma variation.

The IREP program uses equivalent dose as defined in International Commission on Radiological 

Protection (ICRP) Publication 60 (ICRP 1991) using the radiation weighting factor wR defined in 

Table 1 of Publication 60. The NIOSH External Dose Implementation Guide (NIOSH 2002) provides 

conversion factors from ambient dose equivalent H*10 to the organ equivalent dose, and ICRP

Publication 74 (ICRP 1996) provides a calculation of the ambient dose equivalent as shown in 

Figure 3-7 so we can construct the ambient dose equivalent for these spectra. The ratios of the 

 1 The U.S. Department of Labor is ultimately responsible under the EEOICPA for determining the POC.
Document No. ORAUT-OTIB-0009 Revision No. 01 Effective Date: 12/13/2006 Page 11 of 13

neutron ambient dose equivalent from Publication 74 and the neutron dose equivalent from NCRP 

Report 38 (NCRP 1971) are shown in Table 3-4. For the 10- to 100-keV energy group, the ratio of the 

ambient dose equivalent to the neutron dose equivalent is 1.08, while for the above 2-MeV energy 

group, it is 1.121. For the groups where the spectra are not simple multiples of each other there is 

some variation with location.

Table 3-4. Distribution of MTR neutron dose equivalent among IREP energy groups, NTA response, 

and ratio of equivalent dose to dose equivalent.

Location*

Dose equivalent fraction

IREP energy interval

Ambient dose equivalent

Fractional

NTA 

sensitivity

<10 keV >0.8 MeV

10 keV–

100 keV

100 keV–

2 MeV 2M-20M <10 keV

100 keV–

2 MeV Spectrum

EBR-I 1 0.28 0.079 0.47 0.17 0.89 1.38 1.14 0.32

2 0.24 0.077 0.49 0.19 0.88 1.37 1.14 0.36

3 0.24 0.062 0.47 0.23 0.87 1.35 1.13 0.42

4 0.22 0.061 0.47 0.24 0.87 1.35 1.13 0.45

5 0.21 0.084 0.51 0.19 0.88 1.37 1.16 0.35

6 0.21 0.072 0.50 0.22 0.87 1.36 1.15 0.41

7 0.19 0.060 0.49 0.26 0.86 1.34 1.14 0.48

8 0.19 0.059 0.49 0.26 0.85 1.34 1.14 0.49

9 0.18 0.070 0.51 0.24 0.86 1.35 1.15 0.45

10 0.18 0.062 0.50 0.26 0.85 1.34 1.14 0.49

11 0.18 0.049 0.48 0.29 0.84 1.33 1.13 0.54

12 0.17 0.065 0.51 0.26 0.85 1.35 1.15 0.48

13 0.17 0.047 0.48 0.30 0.84 1.32 1.13 0.56

14 0.17 0.036 0.46 0.33 0.83 1.31 1.12 0.61

15 0.17 0.048 0.49 0.30 0.83 1.32 1.13 0.56

16 0.16 0.053 0.50 0.29 0.83 1.33 1.14 0.54

17 0.16 0.040 0.48 0.32 0.82 1.31 1.12 0.60

18 0.16 0.052 0.50 0.29 0.83 1.33 1.14 0.55

19 0.15 0.058 0.51 0.28 0.84 1.34 1.14 0.52

20 0.15 0.044 0.49 0.32 0.82 1.32 1.13 0.59

22 0.15 0.031 0.47 0.35 0.80 1.30 1.12 0.66

23 0.13 0.045 0.50 0.33 0.80 1.32 1.14 0.61

A 0.20 0.075 0.51 0.22 0.92 1.36 1.20 0.41

B 0.17 0.039 0.47 0.32 0.92 1.31 1.17 0.59

C 0.17 0.055 0.49 0.28 0.92 1.33 1.19 0.52

D 0.15 0.065 0.52 0.27 0.92 1.34 1.20 0.50

E 0.13 0.039 0.49 0.34 0.91 1.31 1.18 0.64

F 0.16 0.052 0.49 0.29 0.92 1.33 1.19 0.55

ETR 21 0.14 0.046 0.49 0.32 0.81 1.32 1.13 0.59

ETR 24 0.12 0.037 0.49 0.35 0.78 1.30 1.13 0.65

ETR 25 0.11 0.038 0.50 0.35 0.77 1.30 1.13 0.65

Average 0.18 0.056 0.49 0.28 0.86 1.33 1.15 0.52

Minimum 0.13 0.031 0.46 0.19 0.80 1.30 1.12 0.35

Maximum 0.24 0.084 0.52 0.35 0.92 1.37 1.20 0.66

St Dev 0.030 0.013 0.015 0.043 0.037 0.020 0.026 0.08

* At MTR unless otherwise noted.
Document No. ORAUT-OTIB-0009 Revision No. 01 Effective Date: 12/13/2006 Page 12 of 13 

 

0.1

1

10

100

0.1 1 10 100 1000

Gamma DE Rate(mrem/hr)

Fast Neutron DE Rate (mrem/hr)

Fast Neutron

Fast Insig

Fit 0.419 *Gamma

Figure 3-6. Correlation of fast neutron dose equivalent to 

gamma dose at MTR. 

 

0

1

10

100

1.E-7 1.E-5 1.E-3 1.E-1 1.E+1 1.E+3

Neutron Energy (MeV)

CF (nrem cm^2)

Dose Equiv

ICRP 74

AmbDE

Figure 3-7. ICRP 74 ambient dose equivalent conversion 

factor.
Document No. ORAUT-OTIB-0009 Revision No. 01 Effective Date: 12/13/2006 Page 13 of 13

REFERENCES

Auxier, J. A., W. S. Snyder, and T. D. Jones, (1968) Neutron Interactions and Penetration in Tissue, 

Chapter 6 in Radiation Dosimetry, Second Edition. Vol. 1 Fundamentals, -F. H. Attix and W. C. 

Roesch Ed. Academic Press, New York.

Dennis, J., and W. R. Loosemore, 1961, A Fast-Neutron Counter for Dosimetry, Selected Topics in 

Radiation Dosimetry (Proc. Symp., Vienna, 1960), IAEA Vienna (1961) 443.

Gilbert, R. O., 1987, Statistical Methods for Environmental Pollution Monitoring, Van Nostrand 

Reinhold, New York.

Hankins, D. E., 1961, A Method of Determining the Intermediate Energy Neutron Dose, IDO-16655, 

Idaho Falls, Idaho.

Hertel, N. E. and J. W. Davidson, 1985, “The Response of Bonner Spheres to Neutrons from Thermal 

Energies to 17.3 MeV,” Nucl. Instr. Meth. A238, p 509-516.

ICRP (International Commission on Radiological Protection), 1991, 1990 Recommendations of the 

International Commission on Radiological Protection, Publication 60, Pergamon Press, Oxford, 

England.

ICRP (International Commission on Radiological Protection), 1996, Conversion Coefficients for Use in 

Radiological Protection Against External Radiation, Publication 74, Pergamon Press, Oxford, 

England.

Ing, H. and S. Makra, 1978, Compendium of Neutron Spectra in Criticality Accident Dosimetry, IAEA 

Technical Report Series No. 180, Vienna, Austria.

Knoll, G. F., 1989, Radiation Detection and Measurement, Second Edition, John Wiley and Sons, 

New York, NY.

NCRP (National Council on Radiation Protection and Measurements), 1971, Protection against 

Neutron Radiation, NCRP Report 38.

NIOSH (National Institute for Occupational Safety and Health), 2002, Internal Dose Reconstruction 

Implementation Guideline, OCAS-IG-002, Rev. 0, Office of Compensation Analysis and 

Support, Cincinnati, Ohio, August.

Sommers, J. F. 1959a, Neutron Activity Levels at the MTR due to ANP-1, letter to R. L. Doan (site 

manager), Som-74-59A, August 27.

Sommers, J. F. 1959b, Monitoring Problems Concerning Criticality Hazards, letter to J. R. Huffman, 

Som-14-59A, February 25.

Sommers, J. F. 1962, Thermal Column Measurements, letter to W. H. Burgus, Som-126-62A, 

December 18.