Draft

ADVISORY BOARD ON

RADIATION AND WORKER HEALTH

National Institute for Occupational Safety and Health

REVIEW OF ORAUT-RPRT-0079, REVISION 00,

“EVALUATION OF AIRBORNE EFFLUENT RELEASES FROM 

INITIAL ENGINE TEST NO. 10 AT THE IDAHO NATIONAL 

LABORATORY” 

Contract No. 211-2014-58081 

SCA-TR-2017-PR010, Revision 0 

Prepared by

John Mauro, PhD, CHP 

Steve Marschke

SC&A, Inc.

2200 Wilson Boulevard, Suite 300 

Arlington, Virginia, 22201 

Saliant, Inc.

5579 Catholic Church Road 

Jefferson, Maryland 21755 

October 2017 

DISCLAIMER

This is a working document provided by the Centers for Disease Control and Prevention (CDC) technical 

support contractor, SC&A for use in discussions with the National Institute for Occupational Safety and 

Health (NIOSH) and the Advisory Board on Radiation and Worker Health (ABRWH), including its 

Working Groups or Subcommittees. Documents produced by SC&A, such as memorandum, white paper, 

draft or working documents are not final NIOSH or ABRWH products or positions, unless specifically 

marked as such. This document prepared by SC&A represents its preliminary evaluation on technical 

issues.

NOTICE: This document has been reviewed to identify and redact any information that is protected by 

the Privacy Act 5 U.S.C. § 552a and has been cleared for distribution.
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SC&A, INC.: Technical Support for the Advisory Board on Radiation and Worker 

Health Review of NIOSH Dose Reconstruction Program

DOCUMENT TITLE: 

Review of ORAUT-RPRT-0079, Revision 00, “Evaluation of 

Airborne Effluent Releases from Initial Engine Test No. 10 at the 

Idaho National Laboratory”

DOCUMENT NUMBER/

DESCRIPTION:

SCA-TR-2017-PR010 

REVISION NO.: 0 (Draft)

SUPERSEDES: N/A

EFFECTIVE DATE: October 9, 2017

TASK MANAGER: John Stiver, MS, CHP [signature on file]

PROJECT MANAGER: John Stiver, MS, CHP [signature on file]

DOCUMENT 

REVIEWER(S):

Kathleen Behling [signature on file]

Stephen L. Ostrow, PhD [signature on file] 

John Stiver, MS, CHP [signature on file]

Record of Revisions

Revision 

Number

Effective 

Date Description of Revision

0 (Draft) 10/9/2017 Initial issue
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TABLE OF CONTENTS

Abbreviations and Acronyms ......................................................................................................... 4

1.0 Introduction ......................................................................................................................... 6

2.0 Atmospheric Release Estimates from IET 10 Experiments ................................................ 7

3.0 Atmospheric Dispersion Factors and Associated Internal Dose to Workers Outdoors 

On Site .......................................................................................................................................... 14

4.0 References......................................................................................................................... 16

Appendix A: Critique of ORAUT-RPRT-0079 Supporting Calculations ................................ 18
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ABBREVIATIONS AND ACRONYMS

ABRWH Advisory Board on Radiation and Worker Health 

ANL-W Argonne National Laboratory–West

ANP Aircraft Nuclear Propulsion 

ARA Auxiliary Reactor Area

CDC Centers for Disease Control and Prevention 

CFA Central Facilities Area

Ci curie

Cs cesium

DOE U.S. Department of Energy 

EBR-I Experimental Breeder Reactor-I 

GCRE Gas Cooled Reactor Experiment

H-CL horizontal centerline 

HDE Historical Dose Evaluation

ICPP Idaho Chemical Processing Plant 

ICRP International Commission on Radiological Protection

IET Initial Engine Test

INEL Idaho National Engineering Laboratory 

INL Idaho National Laboratory 

INL-HDE Idaho National Laboratory Historical Dose Evaluation 

NIOSH National Institute for Occupational Safety and Health

NOAA National Oceanic and Atmospheric Administration

NRC U.S. Nuclear Regulatory Commission 

ORAU Oak Ridge Associated Universities

ORAUT Oak Ridge Associated Universities Team

PNL Pacific Northwest Laboratory 

PNNL Pacific Northwest National Laboratory

RSB Radiation Studies Branch 

RWMC Radioactive Waste Management Complex

SPERT Special Power Excursion Reactor Test

Sr strontium 

SRDB Site Research Database
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TAN Test Area North

TRA Test Reactor Area

TREAT Transient Reactor Test Facility

U uranium 

X/Q atmospheric dispersion factor 
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1.0 INTRODUCTION

This report fulfills the June 5, 2017, request by the Advisory Board on Radiation and Worker 

Health (the Board) that SC&A review the National Institute for Occupational Safety and Health 

(NIOSH) report, ORAUT-RPRT-0079, Revision 00, Evaluation of Airborne Effluent Releases 

from Initial Engine Test No. 10 at the Idaho National Laboratory (hereafter referred to as

“RPRT-0079”). 

RPRT-0079 addresses Issue 2 originally raised by SC&A in Review of the NIOSH Site Profile 

for the Idaho National Laboratory, Idaho (SC&A 2005), which dealt with internal doses 

associated with episodic airborne emissions from the Aircraft Nuclear Propulsion (ANP) 

Program at the Test Area North (TAN) facilities at the Idaho National Laboratory (INL). The 

issue was discussed during the Argonne National Laboratory-West (ANL-W)/INL Work Group 

meeting held on November 10, 2015, where NIOSH committed to provide the Work Group with 

a white paper on this subject. 

Detailed descriptions of the ANP Program and specific Initial Engine Test No. 10 (IET 10) 

experiments are provided in RPRT-0079, DOE 1991a, DOE 1991b, DOE 1991c, and SC&A & 

SENES 2005. This report is organized in two major sections, one dealing with estimates of the 

releases of radionuclides from IET 10 experiments (also referred to as runs), and the other 

dealing with the models and assumptions used to derive the outdoor doses to workers at INL due 

to those releases.
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2.0 ATMOSPHERIC RELEASE ESTIMATES FROM IET 10 

EXPERIMENTS

The estimates and subsequent review of the airborne emission and associated doses from IET 10 

experiments have a long and complex history, which are described in DOE 1991a, DOE 1991b, 

SC&A & SENES 2005, SC&A 2005, and RPRT-0079, and are not repeated here in detail. 

However, as part of the review of this issue, it is instructive to briefly describe the major 

investigations performed by the U.S. Department of Energy (DOE), SC&A (for the Radiation 

Studies Branch [RSB] of the Centers for Disease Control and Prevention [CDC]), and now 

NIOSH (by the Oak Ridge Associated Universities Team [ORAUT]). In particular, this section 

reviews the purpose of each investigation, the type and magnitude of the differences in the 

source terms and doses, and the reasons for these differences.

The first investigation was performed by the Idaho National Engineering Laboratory Historical 

Dose Evaluation (INEL-HDE, or HDE) Task Group formed by DOE in December 1988, which 

published its findings in 1991 (DOE 1991a, b). These investigations were part of the historical 

dose reconstruction evaluation initiated over concern that weapons complex facilities might have 

released large amounts of radionuclides to the atmosphere, which could have had adverse 

impacts on public health at many locations throughout the United States. INL1 was only one of 

many facilities for which these types of offsite dose reconstructions were performed. The 

primary goal of these dose reconstructions was to determine whether follow-up 

radioepidemiological investigations of the populations near the various weapons complex 

facilities were warranted considering the atmospheric releases that occurred over the many 

decades of operation.

1 The laboratory is currently named the Idaho National Laboratory (INL) but went by several other names in 

previous time periods. 

The HDE Task Group, and later SC&A as a consultant to the CDC RSB, concluded that the 

atmospheric releases from the IET 10 series of experiments had a substantial potential for large 

offsite population doses. The releases from the IET 10 experiments were estimated by DOE to be 

130,000 curies (Ci) from IET 10A and 140,000 Ci from IET 10B (see Table 5 of SC&A 2015, as 

well as SC&A & SENES 2005, where the respective releases are reported as 1.28×105

 Ci and 

1.36×105

 Ci). The radionuclides identified in the DOE HDE reports are noble gases (xenon and 

krypton isotopes), which have little potential for internal dose, fission products (strontium-90 

[Sr-90] and cesium-137 [Cs-137], among others), and uranium (U) isotopes (e.g., U-234, U-235, 

and U-238). 

The second major assessment of the atmospheric releases from INL, performed by SC&A for the 

CDC (SC&A & SENES 2005), was initiated as a result of uncertainties in the estimates of the 

atmospheric releases and associated offsite doses at INL. SC&A’s initial screening determined 

that atmospheric releases from IET experiments 3, 4, and 10 had the greatest potential for offsite 

exposure of all the INL releases, as well as the largest uncertainties in both releases and offsite 

doses. SC&A then investigated these releases and associated offsite doses in more detail in a 

2005 report, A Critical Review of Source Terms for Select Initial Engine Tests Associated with 

the Aircraft Nuclear Propulsion Program at INEL (SC&A & SENES 2005). With respect to IET 

 
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10 experiments, SC&A estimated atmospheric releases of 2×106 Ci, about 10-fold higher than 

those estimated by DOE in the HDE Task Group investigations. 

SC&A’s review of the INL site profile (SC&A 2005) noted that NIOSH had employed the DOE 

HDE Task Group estimates of the atmospheric releases from IET 10 experiments as the bases for 

its onsite dose calculations (not just for offsite doses). As a result, SC&A reported that these 

values were underestimated by about a factor of 10 based on the investigations SC&A had 

previously performed for the CDC in 2005. 

The latest IET 10 study, NIOSH’s RPRT-0079, responds to SC&A’s Issue 2 in its site profile 

review regarding the IET 10 release estimates and constitutes the third attempt (after DOE and 

CDC/SC&A) to place a reasonable but bounding estimate on these atmospheric releases. 

Table 4-2 of RPRT-0079 provides an estimate 1.77×103 Ci of the total fission product releases (it 

does not include noble gases) from the IET 10 experiments. Based on SC&A’s review of the 

NIOSH spreadsheets in the Site Research Database (SRDB) in support of RPRT-0079, SC&A 

believes that Table 4-2 contains several typographical errors, as follows:

1) The list of IET 10 runs that were included in the RPRT-0079 calculation is given as 12, 

13, 15, 17, 21, 24, 25, 28, 29, 37, 42, 43, 45, 46, 47, 52, 53, 54, 55, and 56. However, the 

IET 10 runs that were included in the Excel calculations differ slightly: 12, 13, 15, 17, 21, 

24, 25, 28, 29, 37, 42, 43, 45, 46, 47A&B, 48A, 52, 53, 54, 55, and 56A&B. 

2) Table 4-2 only gives the IET 10 releases associated with Phase I of the IET 10 

experiments, i.e., runs 12, 13, 15, 17, and 21. It should be revised to include the releases 

from Phases II and III, as shown below in Table 1. Note that the Phase I column matches 

exactly the RPRT-0079 Table 4-2 releases and that the Phase I releases are about two 

orders of magnitude less that the total releases. Table 1 provides the full set of releases 

from IET 10 as provided by ORAUT in the SRDB spreadsheets provided in support of 

RPRT-0079. 

Table 1. IET 10 Releases from RPRT-0079 SRDB Spreadsheets (ORAUT 2017a, b, c), Ci 

Nuclide

Phase I

Runs: 12, 13, 15, 

17, & 21

Phase II

Runs: 24, 25, 28, 

& 29

Phase III

Runs: 37, 42, 43, 45, 46, 

47A, 47B, 48A, 52, 53, 

54, 55, 56A, & 56B

Total

All 23 runs

Br-84 3.03E+00 2.63E+01 5.58E+01 8.52E+01

Rb-89 6.15E+01 6.67E+02 3.44E+03 4.17E+03

Sr-89 5.82E-01 5.70E+00 9.87E+01 1.05E+02

Sr-90 1.84E-04 3.17E-03 1.30E-01 1.33E-01

Sr-91 3.99E+00 5.46E+01 6.79E+02 7.38E+02

Sr-92 4.22E+00 5.50E+01 6.19E+02 6.78E+02

Y-91 1.95E-02 1.01E+00 5.89E+01 5.99E+01

Y-92 2.23E+00 5.49E+01 7.12E+02 7.69E+02

Y-93 2.01E+00 4.08E+01 5.65E+02 6.08E+02
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Nuclide

Phase I

Runs: 12, 13, 15, 

17, & 21

Phase II

Runs: 24, 25, 28, 

& 29

Phase III

Runs: 37, 42, 43, 45, 46, 

47A, 47B, 48A, 52, 53, 

54, 55, 56A, & 56B

Total

All 23 runs

Zr-95 3.12E-02 1.27E+00 6.33E+01 6.46E+01

Zr-97 1.32E+00 2.85E+01 4.28E+02 4.57E+02

Nb-96 1.06E-04 2.38E-03 3.72E-02 3.97E-02

Mo-99 5.08E-01 1.41E+01 2.80E+02 2.95E+02

Ru-103 2.45E-02 9.79E-01 4.53E+01 4.63E+01

Ru-105 5.36E-01 9.10E+00 1.11E+02 1.20E+02

Ru-106 3.55E-04 1.47E-02 8.32E-01 8.47E-01

Sb-129 3.51E-01 5.94E+00 7.22E+01 7.85E+01

Te-131 1.55E+00 1.17E+01 1.05E+02 1.18E+02

Te-131m 5.57E-02 1.30E+00 2.11E+01 2.25E+01

Te-132 3.21E-01 9.30E+00 1.96E+02 2.05E+02

Te-133m 1.73E+00 1.46E+01 1.44E+02 1.61E+02

Te-134 3.02E+00 2.38E+01 2.20E+02 2.47E+02

I-131 6.49E-01 3.24E+01 2.43E+02 2.77E+02

I-132 1.28E-01 3.76E+00 3.34E+01 3.73E+01

I-133 8.46E+00 2.47E+02 9.78E+02 1.23E+03

I-134 2.70E+00 3.29E+01 1.13E+02 1.48E+02

I-135 2.16E+00 4.63E+01 1.50E+02 1.98E+02

Cs-137 4.34E-03 4.17E-02 7.42E-01 7.88E-01

Cs-138 1.61E+03 1.07E+04 9.90E+04 1.11E+05

Ba-139 5.86E+01 3.93E+02 4.06E+03 4.51E+03

Ba-140 2.68E-01 6.29E+00 1.89E+02 1.96E+02

Ba-141 7.17E-01 6.88E+00 4.13E+01 4.89E+01

Ba-142 6.28E-02 1.02E+00 3.35E+00 4.43E+00

La-141 3.67E+00 5.73E+01 6.82E+02 7.43E+02

La-142 4.70E+00 4.93E+01 5.26E+02 5.80E+02

Ce-141 3.87E-02 1.92E+00 9.46E+01 9.66E+01

Ce-143 8.52E-01 2.02E+01 3.33E+02 3.54E+02

Ce-144 5.97E-03 2.48E-01 1.38E+01 1.41E+01

Pr-143 4.60E-02 2.99E+00 1.46E+02 1.49E+02

Pr-144 5.96E-03 2.48E-01 1.38E+01 1.41E+01

U-234 9.07E-05 2.39E-04 1.58E-03 1.91E-03

U-235 2.89E-06 7.76E-06 5.02E-05 6.09E-05

U-238 2.69E-08 7.08E-08 4.68E-07 5.65E-07
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It appears that the doses derived in RPRT-0079 are based on the total releases provided in 

ORAUT 2017a and not the values in Table 4-2. However, as discussed below, the releases used 

in RPRT-0079 to derive the outdoor internal exposures to workers at INL are in total about a 

factor 1.6 lower than those estimated in SC&A & SENES 2005. 

To investigate the reasons for these differences, SC&A prepared Table 2, which uses the 

radionuclide releases in the spreadsheet in ORAUT 2017a (SRDB Ref. ID 166017) as the 

starting point, and compares those releases to the releases for the radionuclides reported by 

SC&A and the DOE HDE Task Group. Table 2 does not include noble gases because they do not 

contribute substantially to the internal doses. In total, SC&A’s estimates are about 1.6 times 

higher than those NIOSH estimated in support of RPRT-0079 and about 7.6 times higher than 

those estimated by the DOE HDE Task Group. However, for many individual radionuclides, 

such as radioiodines, the SC&A & SENES 2005 estimates are 2 to 3 times higher. 

Table 2. Estimates of the Total Atmospheric Releases from all IET Runs (Excluding Noble 

Gases) as Derived by DOE, SC&A, and ORAUT, Ci

Nuclide Half-life DOE HDE 

(DOE 1991) 

SC&A (SC&A & 

SENES 2005) 

RPRT-0079

(ORAUT

2017a)

Ratio

(SC&A/

ORAUT)

Br-84 6.0 m 2.06E+01 2.26E+02 8.52E+01 2.65E+00

Rb-89 15.4 m 1.04E+03 8.11E+03 4.17E+03 1.94E+00

Sr-89 52.7 d 1.87E+01 1.46E+02 1.05E+02 1.39E+00

Sr-90+D 29 y 2.33E-02 1.82E-01 1.33E-01 1.37E+00

Sr-91+D 9.5 h 1.52E+02 1.19E+03 7.38E+02 1.61E+00

Sr-92 2.71 h 1.35E+02 1.05E+03 6.78E+02 1.55E+00

Y-91 58.8 d 1.02E+01 7.95E+01 5.99E+01 1.33E+00

Y-92 3.53 h 1.56E+02 1.21E+03 7.69E+02 1.57E+00

Y-93 10.3 h 1.29E+02 1.01E+03 6.08E+02 1.66E+00

Zr-95+D 64 d 1.12E+01 8.70E+01 6.46E+01 1.35E+00

Zr-97 17 h 1.01E+02 7.85E+02 4.57E+02 1.72E+00

Nb-96 23.35 h 8.82E-03 6.88E-02 3.97E-02 1.73E+00

Mo-99 66 h 5.98E+01 4.66E+02 2.95E+02 1.58E+00

Ru-103 +D 39 d 8.02E+00 6.26E+01 4.63E+01 1.35E+00

Ru-105 4.4 h 2.43E+01 1.90E+02 1.20E+02 1.58E+00

Ru-106+D 368 d 1.46E-01 1.13E+00 8.47E-01 1.33E+00

Sb-129 4.4 h 1.58E+01 1.24E+02 7.85E+01 1.58E+00

Te-131 25 m 2.42E+01 1.89E+02 1.18E+02 1.60E+00

Te-131m 30 h 4.97E+00 3.88E+01 2.25E+01 1.72E+00

Te-132+D 78 h 4.08E+01 3.18E+02 2.05E+02 1.55E+00

Te-133m 55 m 3.24E+01 2.53E+02 1.61E+02 1.57E+00

Te-134 42 m 5.04E+01 3.93E+02 2.47E+02 1.59E+00

I-131 8.05 d 5.49E+01 5.87E+02 2.77E+02 2.12E+00
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Nuclide Half-life DOE HDE 

(DOE 1991) 

SC&A (SC&A & 

SENES 2005) 

RPRT-0079

(ORAUT

2017a)

Ratio

(SC&A/

ORAUT)

I-132 2.3 h 9.18E+01 9.18E+01 3.73E+01 2.46E+00

I-133 20.3 h 3.86E+02 3.80E+03 1.23E+03 3.09E+00

I-134 52.0 m 3.43E+02 3.43E+02 1.48E+02 2.32E+00

I-135 6.68 h 5.31E+02 5.31E+02 1.98E+02 2.68E+00

Cs-137+D 30 y 1.40E-01 1.09E+00 7.88E-01 1.38E+00

Cs-138 32.2 m 2.23E+04 1.74E+05 1.11E+05 1.57E+00

Ba-139 82.9 m 8.86E+02 6.91E+03 4.51E+03 1.53E+00

Ba-140+D 13 d 3.48E+01 2.71E+02 1.96E+02 1.38E+00

Ba-141 18 m 1.14E+01 8.86E+01 4.89E+01 1.81E+00

Ba-142 11 m 1.50E+00 1.17E+01 4.43E+00 2.64E+00

La-141 3.87 h 1.49E+02 1.16E+03 7.43E+02 1.56E+00

La-142 92.5 m 1.16E+02 9.03E+02 5.80E+02 1.56E+00

Ce-141 32.5 d 1.67E+01 1.30E+02 9.66E+01 1.35E+00

Ce-143 33 h 7.77E+01 6.06E+02 3.54E+02 1.71E+00

Ce-144 284 d 2.42E+00 1.89E+01 1.41E+01 1.34E+00

Pr-143 13.59 d 2.48E+01 1.94E+02 1.49E+02 1.30E+00

Pr-144 17 m 2.42E+00 1.89E+01 1.41E+01 1.34E+00

U-234 2.47x105 y 4.29E-04 3.86E-03 1.91E-03 2.02E+00

U-235 7x108 y 1.37E-05 1.23E-04 6.09E-05 2.02E+00

U-238 2.5x109 y 1.27E-07 1.14E-06 5.65E-07 2.02E+00

Total — 2.71E+04 2.06E+05 1.29E+05 1.60E+00

Table 4-1 of RPRT-0079 provides a convenient summary of the multiplication factors that adjust 

(i.e., correct) the release rates for the IET experiments provided by the DOE HDE Task Group.

Table 3 is a reproduction of that table. 

Table 3. SC&A and SENES (2005) Adjustment Factors

Nuclides

Adjustment 

factor 

Br-84 11.0

I-131 10.7

I-133 9.8

U-234, U-235, U-238 9.0

Sr-90 2.2

Ar-41, I-132, I-134, I-135 1.0

Remaining 40 nuclides 7.8

Source: Reproduced from RPRT-0079, Table 4-1.

The differences between the total fission product releases estimated by SC&A as compared to 

those derived by DOE are due to the following reasons: 
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• SC&A believes that an additional 1.37 fuel cartridges were severely damaged. 

• SC&A believes that there was 25% higher fuel burnup among the severely damaged fuel. 

• SC&A used a higher release fraction for iodines released from severely damaged fuel 

(0.8 versus 0.5). 

• SC&A used a release fraction of 0.006 for halogens and 0.002 for fission products for 

undamaged fuel, while DOE did not provide release estimates for undamaged fuel. 

SC&A & SENES 2005 provides a detailed description of the bases for the differences between 

the SC&A and DOE HDE Task Group estimates. These differences were discussed extensively 

with representatives of DOE and the CDC, and DOE representatives stated that they had no 

objections to the methods and assumptions used by SC&A to derive the releases from IET 10. 

(There is no information available online attesting to this conclusion, but it can be attested to by 

the participants, including C.M. Wood (the CDC project manager), and John Mauro and Hans 

Behling, the contractors providing technical support to the CDC). 

The differences between the release estimates derived by SC&A and those derived by NIOSH in 

RPRT-0079 (as provided in the spreadsheets supporting the report) are relatively small (a factor 

of 1.6 in total) but are worth exploring. Based upon the RPRT-0079 excerpts below and SC&A’s 

review of the “166017_INEL – IET 10 Releases and Worker Intakes Spreadsheet.xlsx” Excel file

(ORAUT 2017a), SC&A concludes that NIOSH did not recalculate the release for any of the IET 

10 runs. Rather, NIOSH used the releases that were calculated by the DOE HDE Task Group and 

adjusted them by the factors developed by SC&A & SENES 2005, as summarized in Table 4-1 

of RPRT-0079 (Table 3 above). Section 4.4 of RPRT-0079 (page 31) also provides the following 

description of the approach used by NIOSH to derive the releases: 

Because of the complexity associated with reconstructing the IET #10 releases 

and because not all of the necessary information to calculate more accurate or 

defensible release estimates is available, the ORAU Team has relied on the work 

that was previously completed and reported.... The ORAU Team still considers 

the original fission product releases for IET #10 in the HDE documentation 

(DOE 1991c) to be the best values that are consistent with the available 

information. However, there is a reasonable chance that the original uranium 

releases in the HDE were underestimated. Therefore, to ensure that none of the 

IET #10 releases were underestimated, the adjusted release values were 

retabulated based on the information in SC&A and SENES (2005). 

Section 5.1 of RPRT-0079 (page 33) also states the following:

Of the 32 runs, 12 of the runs (5, 9, 11, 19, 20, 26, 32, 38, 40, 48, 49, and 57) had 

air concentrations of zero for all four downwind locations, and therefore did not 

have the potential to contribute to the internal doses of the INL workers. 

Therefore, the releases from these runs were excluded from the calculations for 

this report. 

It appears that, by using the SC&A & SENES 2005 adjustment factors as applied to the releases 

estimated by the DOE HDE Task Group, the NIOSH estimates adopt the basic approach used by 
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SC&A. However, NIOSH made some adjustments that SC&A believes account for the 

differences in the releases between those estimated in SC&A & SENES 2005 and those used by 

NIOSH to derive the doses in RPRT-0079. The first difference appears to be the elimination of 

12 of the releases identified in Section 5.1 of RPRT-0079 for the reasons described above. To 

confirm that the rationale for excluding selected releases from IET 10 runs is reasonable, SC&A 

reviewed the spreadsheets used by NIOSH to derive the releases and onsite doses. The results of 

our investigations, as described in Appendix A, reveal that NIOSH appropriately eliminated the 

releases from those 12 runs because, at the time of those runs, the wind was blowing in a 

direction that could not have resulted in onsite doses. Attachment A also found that NIOSH 

incorrectly eliminated the releases from certain runs. However, this is a minor point that is more 

than accommodated by the other assumptions used by NIOSH to derive the doses. Therefore, the 

rationale for the differences between the releases as in SC&A & SENES 2005 and those derived 

by NIOSH in support of RPRT-0079 appear reasonable. 

In addition, starting on page 30 RPRT-0079 provides seven significant points regarding the 

releases estimated in SC&A & SENES 2005. In summary, these seven points explain that: 

1) The SC&A & SENES 2005 report does not provide sufficient detail about the basis for 

the estimated releases. 

2) There is new evidence that the peak temperature of the fuel never reached 3,200 degrees 

Fahrenheit (which would imply that the releases were lower than those estimated by both 

DOE and SC&A). 

3) NIOSH has a different interpretation of the degree of fuel damage and associated isotopic 

releases as implied by inspection of the residue associated with the damaged fuel. 

SC&A believes these points might be important, and, if they are correct, the releases as estimated 

in SC&A & SENES 2005 and by the DOE HDE Task Group may have been substantially 

overestimated. However, it appears that the releases, as estimated by NIOSH in deriving the 

doses reported in RPRT-0079, do not take into account these seven points, but the points are 

discussed in RPRT-0079 to demonstrate the conservatism inherent in the release estimates that 

are used in RPRT-0079. These seven points are quite complex, and SC&A has no basis for 

disputing these points and did not investigate these issues further because they were not 

incorporated into the analyses in RPRT-0079. 

The above review reveals that the release estimates appear to be reasonable, taking the following

into consideration: 

1) the relatively small differences between those derived by SC&A (SC&A & SENES 2005) 

and those derived by NIOSH (RPRT-0079) 

2) the uncertainties in the estimates

3) our confirmation that the differences between the release estimates as derived by SC&A 

in SC&A & SENES 2005 and those derived by NIOSH in RPRT-0079 are justified based 

on inspection of the wind direction at the time of each release 
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3.0 ATMOSPHERIC DISPERSION FACTORS AND ASSOCIATED 

INTERNAL DOSE TO WORKERS OUTDOORS ON SITE 

Section 5.0 of RPRT-0079 presents a detailed discussion of the models and assumptions used by 

NIOSH to derive the internal doses to onsite workers outdoors. A realistic estimate of the 

internal doses to workers due to atmospheric releases from the IET 10 runs would require 

information on the location of workers outdoors at the time of each episodic release associated 

with the 32 IET 10 runs tabulated in Table 3-1 of RPRT-0079.2

2 Note that Section 5.1 of RPRT-0079 provides a sound basis for excluding 12 of those runs based on information 

about the direction of the wind (see Figure 5-1 of RPRT-0079, which was excerpted from DOE-1991a, and which 

was based on a puff advection model [MESODIF] described in DOE 1991a, b, and c, which was used for offsite 

dose reconstruction by DOE).

 In addition, meteorological 

conditions (wind speed, direction, and stability class; i.e., joint frequency data) would be 

required for the time periods associated with each run. Though this latter information is 

available, the overall calculation would require a significant level of effort and, in the end, would 

be a futile exercise because the actual time and location of the workers outdoors is not known. 

Instead, RPRT-0079 adopts a simple and extremely claimant-favorable approach to place an 

upper bound on the internal doses to onsite workers outdoors. 

Given the wind trajectories depicted in Figure 5-1 of RPRT-0079, NIOSH identified eight 

locations on site where workers might have been outdoors during the IET 10 runs (see Table 5-1 

of RPRT-0079). Given the releases associated with each run (Table 2 provides the total releases 

from all IET runs combined) and the designated downwind receptor locations, RPRT-0079 

derives the atmospheric dispersion factors at each hypothetical receptor location for each run 

using a conventional Gaussian dispersion model. In applying this model, the report uses realistic 

meteorological data collected on site at the time of the releases and several simplifying, but 

highly conservative, assumptions to derive the atmospheric dispersion factors at each receptor 

location for each IET 10 release. Table A-1 of RPRT-0079 presents the hourly meteorological 

data at the time of each test (Tests 28, 29, 37, 42, 43, 45, 46, 47a and b, 52, 53, 54, 55, and 56a 

and b) considered applicable to this analysis (i.e., because they had the potential to cause internal 

doses to workers on site outdoors, as discussed above). The data in Table A-1 include the wind 

direction, wind speed, and the lower level (20 feet) and upper level (150 feet) temperatures that 

were prevalent at the beginning of each hour during each IET 10 run. 

NIOSH could have run a puff advection model to derive the atmospheric dispersion factors at 

any location as a function of time. However, such an elaborate analysis would be an overreach 

because we do not have real information about the actual locations of the workers outdoors 

during the releases. Instead, ORAUT used a conventional centerline Gaussian dispersion model 

to derive the atmospheric dispersion factors at each of the eight locations for each of the IET 10 

releases. In performing these calculations, ORAUT found that the highest atmospheric dispersion 

factors were obtained by assuming Stability Class E.3

3 SC&A independently reviewed the X/Q calculations provided in the NIOSH spreadsheets cited in RPRT-0079 and 

confirmed the validity of the derived values (see Attachment A). 

In reality, the actual stability class 

associated with each hour of each release and each location likely varied among the six stability 

classes (A through E) and probably overestimates the real atmospheric dispersion factors 

experienced at each location during all IET 10 runs by several-fold. (See Figure 5-4 and 

 
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Table 5-4 of RPRT-0079, which shows the spread in sigma z [a measure of vertical atmospheric 

dispersion as a function of receptor location] and atmospheric dispersion factors, respectively; 

also see Attachment A to this report.) In addition, inherent in the approach adopted by NIOSH is 

the assumption that the outdoor worker at each location was located directly under the plume 

centerline for the duration of each run. This assumption (i.e., that the worker is located 

beneath the centerline of the plume during all releases) makes the NIOSH dose calculation 

extremely conservative. Another conservative assumption is that, in derivation of the 

atmospheric dispersion factors, no credit was taken to account for plume rise associated with the 

temperature of the gaseous effluents from the elevated stack. 

The results of these calculations are provided in Table 7-1 of RPRT-0079, reproduced here as

Table 4. 

Table 4. IET 10 Internal Doses for Selected Organs (rem)

Organ Total dose

Bone 7.81E–03 

ET1a 1.22E+01 

Lung 2.35E–02 

Kidney 1.56E–03 

Liver 3.19E–03 

Lower Large Intestine 1.85E–02 

Upper Large Intestine 1.30E–02 

Red Bone Marrow 3.31E–03 

Skin 8.48E–04 

Thyroid 2.11E–01 a ET1 – Extrathoracic Region 1 in the ICRP’s human 

respiratory model (ICRP 1994b).

Source: Reproduced from RPRT-0079, Table 7-1.

Section 8 of RPRT-0079 provides additional discussion of the uncertainties and conservatism 

inherent in these dose calculations. 

SC&A concludes that, although NIOSH derives releases that are a factor of about 1.6 lower than 

those derived in SC&A & SENES 2005, the differences are small, considering the uncertainties 

in the assumptions used to derive the releases. In addition, our independent check of the wind 

direction during each test confirmed that NIOSH has a sound basis for excluding the releases 

from several tests (i.e., at the time of those tests, the wind was blowing in a direction that could 

not have exposed workers on site). SC&A concludes that the dose reconstruction data, 

methods, and assumptions in RPRT-0079 are scientifically sound and claimant favorable. 
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4.0 REFERENCES

DOE 1991a. Idaho National Engineering Laboratory Historical Dose Evaluation, Volume 1, 

DOE/ID-12119, U.S. Department of Energy, Idaho Operations Office, Idaho Falls, Idaho. 

August 1991. [SRDB Ref. ID 1107] 

DOE 1991b. Idaho National Engineering Laboratory Historical Dose Evaluation, Volume 2: 

Appendices, DOE/ID-12119, U.S. Department of Energy, Idaho Operations Office, Idaho Falls, 

Idaho. August 1991. [SRDB Ref. ID 1109] 

DOE 1991c. Idaho National Engineering Laboratory Historical Dose Evaluation Quality 

Assurance Files – Source Term Quality Control Tasks (Episodic Releases) – IET #10 Source 

Term Characterization, DOE/ID-12119-QAF-026, U.S. Department of Energy, Idaho Operations 

Office, Idaho Falls, Idaho. March 1991. [SRDB Ref. ID 88731] 

ICRP 1994. Dose Coefficients for Intakes of Radionuclides by Workers, Publication 68, 

International Commission on Radiological Protection, Pergamon Press, Oxford, England. 

July 1994. [SRDB Ref. ID 22731] 

NOAA 2017. “Pasquill Stability Classes,” Web page, Air Resources Laboratory, National 

Oceanic and Atmospheric Administration. Accessed September 2017 at 

https://www.ready.noaa.gov/READYpgclass.php 

NRC 1977. Methods for Estimating Atmospheric Transport and Dispersion of Gaseous Effluents 

in Routine Releases from Light-Water-Cooled Reactors, Regulatory Guide 1.111, Revision 1, 

U.S. Nuclear Regulatory Commission, Washington, DC. July 1977. 

ORAUT 2017a. “166017_INEL – IET 10 Releases and Worker Intakes Spreadsheet.xlsx,” 

Revision 0 [Excel spreadsheet], Oak Ridge Associated Universities Team, Oak Ridge, 

Tennessee. March 13, 2017. [SRDB Ref. ID 166017] 

ORAUT 2017b. “166018_INEL - Dose Summary for IET 10 Releases Spreadsheet.xlsx,” 

Revision 0 spreadsheet, Oak Ridge Associated Universities Team, Oak Ridge, Tennessee. 

March 21, 2017. [SRDB Ref. ID 166018] 

ORAUT 2017c. “165830_INEL - IET 10 Releases from INEL-HDE Rev 0.xlsx,” Rev. 0 

spreadsheet, Oak Ridge Associated Universities Team, Oak Ridge, Tennessee. February 19, 

2017. [SRDB Ref. ID 165830] 

ORAUT-RPRT-0079. 2017. Evaluation of Airborne Effluent Releases from Initial Engine Test 

No. 10 at the Idaho National Laboratory, Revision 00, National Institute of Occupational Safety 

and Health, Cincinnati, Ohio. April 28, 2017. 

PNL 1995. Environmental Settings for Selected U.S. Department of Energy Installations—

Support Information for the Programmatic Environmental Impact Statement and the Baseline 

Environmental Management Report, PNL-10550, Pacific Northwest Laboratory. May 1995. 

[SRDB upload pending] 
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SC&A & SENES 2005. A Critical Review of Source Terms for Select Initial Engine Tests 

Associated with the Aircraft Nuclear Propulsion Program at INEL, SC&A, Inc. McLean, VA, 

and SENES Oak Ridge, Inc., Oak Ridge, Tennessee. July 2005. [SRDB Ref. ID 103215] 

SC&A 2005. Review of the NIOSH Site Profile for the Idaho National Laboratory, Idaho, SCATR-TASK1-0005, Revision 0, SC&A, Inc. McLean, VA, September 23, 2005. 

SC&A 2015. Review of NIOSH Strategy for Reconstructing Internal Doses to Workers at Test 

Area North, SCA-TR-2015-SEC0074A, SC&A, Inc. Vienna, VA, September 28, 2015. 

SRNL-STI-2012-00055. 2012. A Recommended Pasquill-Gifford Stability Classification Method 

for Safety Basis Atmospheric Dispersion Modeling at SRS, Revision 0, C. H. Hunter, Savannah 

River National Laboratory, Aiken, South Carolina. March 2012. [SRDB upload pending.]
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APPENDIX A: CRITIQUE OF ORAUT-RPRT-0079 SUPPORTING

CALCULATIONS

A.1. IET 10 RADIONUCLIDE RELEASE ADJUSTMENT

In this section, SC&A reviews the approach NIOSH used to limit the number of IET 10 runs 

included in their analysis. To perform the review, SC&A obtained the IET 10 run dates from 

RPRT-0079, Table 3-1, and the meteorological data from RPRT-0079, Attachment A. Not 

accounting for wind speed, SC&A included any IET 10 run that blew toward the SE (135°) to 

SW (225°) (See Figure A-1). Thus, if the recorded wind direction was between 0° and 45° or 

between 315° and 360° at any time during the run, then SC&A included that run’s release. 

Figure A-1. INL Site and Surrounding Areas; Modified by SC&A from 

ORAUT-RPRT-0079, Figure 5-1 

With this simple approach, SC&A agrees with NIOSH on including or excluding 25 of the 37 

IET #10 runs. Of the 12 runs for which we disagreed, SC&A’s simplified analysis excluded 10 

runs that NIOSH included. This is likely due to the fact that NIOSH accounted for travel time; 

i.e., if the recorded wind blew toward the four receptor points at any time during the release or 
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during the travel time, then NIOSH included that run’s release in their analysis. Extending the 

period of interest by 2 hours would move 7 of the 10 previously excluded runs to being included, 

and in agreement with NIOSH. Extending the period of interest by 3, 4, and 13 hours would 

include the remaining 3 previously excluded runs, in agreement with NIOSH.

Of more concern are the 2 runs that NIOSH excluded but that the SC&A analysis suggests 

should be included, namely, runs 48b and 57b. For run 48b, there are 3 hours of meteorological 

data (i.e., 03, 04, and 05 hours on February 24, 1958) showing 0.0° wind direction—blowing 

directly toward the South. Thus, by NIOSH’s ground rules these hours should be included in the 

analysis. For run 57b, there is only a single hour of meteorological data, showing a 22.5° wind 

direction—blowing directly towards the SSW. By NIOSH’s ground rules, this hour should 

likewise be included in the analysis. Run 57b is not a significant contributor to the radionuclide 

releases (<1% to the total release); however, run 48b is a significant contributor, about an 

addition third to the total release.

Table A-1. Results of SC&A Review of NIOSH IET 10 Release Modifications 

Phase –

Run SC&A Review Result Agree

I – 5 SC&A and NIOSH agree to Exclude Yes

I – 9a SC&A and NIOSH agree to Exclude Yes

I – 9b SC&A and NIOSH agree to Exclude Yes

I – 11 SC&A and NIOSH agree to Exclude Yes

I – 12 SC&A and NIOSH agree to Exclude Yes

I – 13 SC&A and NIOSH agree to Exclude Yes

I – 15 SC&A and NIOSH agree to Exclude Yes

I – 17 SC&A and NIOSH agree to Exclude Yes

I – 19 SC&A and NIOSH agree to Exclude Yes

I – 20 SC&A and NIOSH agree to Exclude Yes

I – 21 SC&A and NIOSH agree to Exclude Yes

II – 24 Agree to Include, when time extended by 4 hrs Yes

II – 25 Agree to Include, when time extended by 2 hrs Yes

II – 26 SC&A and NIOSH agree to Exclude Yes

II – 28 SC&A and NIOSH agree to Exclude Yes

II – 29 SC&A and NIOSH agree to Exclude Yes

II – 32 SC&A and NIOSH agree to Exclude Yes

III – 37 SC&A and NIOSH agree to Exclude Yes

III – 38 SC&A and NIOSH agree to Exclude Yes

III – 40 SC&A and NIOSH agree to Exclude Yes

III – 42 Agree to Include, when time extended by 1 hr Yes

III – 43 Agree to Include, when time extended by 2 hrs Yes

III – 45 Agree to Include, when time extended by 1 hr Yes

III – 46 Agree to Include, when time extended by 1 hr Yes
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Phase –

Run SC&A Review Result Agree

III – 47a SC&A and NIOSH agree to Exclude Yes

III – 47b Agree to Include, when time extended by 1 hr Yes

III – 48a SC&A and NIOSH agree to Exclude Yes

III – 48b SC&A Included, NIOSH Excluded No

III – 49 SC&A and NIOSH agree to Exclude Yes

III – 52 SC&A and NIOSH agree to Exclude Yes

III –53 SC&A and NIOSH agree to Exclude Yes

III – 54 Agree to Include, when time extended by 1 hr Yes

III – 55 Agree to Include, when time extended by 3 hrs Yes

III – 56a Agree to Include, when time extended by 13 hrs Yes*

III – 56b SC&A and NIOSH agree to Exclude Yes

III – 57a SC&A and NIOSH agree to Exclude Yes

III – 57b SC&A Included, NIOSH Excluded No

Table A-2 summarizes the wind direction analysis and shows that most of the IET 10 runs were 

made when the wind was blowing out of the NE or North sectors. 

Table A-2. Summary of Wind Direction Analysis 

Affected Sector

# of IET 10 

Runs – 

SC&A

# of IET 10 

Runs – 

NIOSH

Total 

Non-Noble Gas 

Release (Ci) – 

SC&A*

Total 

Non-Noble Gas 

Release (Ci) – 

NIOSH

SE 0 0 0.00E+00 0.00E+00

SSE 1 1 2.80E+03 2.80E+03

S 9 9 1.85E+05 1.85E+05

SSW 5 4 4.28E+03 3.63E+03

SW 10 9 8.44E+04 3.27E+04

Totals 25 23 2.76E+05 2.24E+05

* The SC&A releases include IET 10 runs 48b and 57b, while the NIOSH releases do not 

include these two runs.

Table A-3 presents a breakdown by sectors of the IET 10 runs. This table can be used to 

determine which runs are the most significant contributors to the total IET 10 release, as well as 

the releases toward a particular downwind sector.
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Table A-3. IET 10 Releases as a Function of Wind Direction, 

Percentage of Total IET 10 Release 

Wind 

Direction*

Associated with 

IET 10 Release

SC&A Release

Total

SC&A Release

Per Sector

NIOSH Release

Total

NIOSH Release

Per Sector

NNW

54 1.01% 100.00% 1.25% 100.00%

NNW Sector 

Total 1.01% 100.00% 1.25% 100.00%

N – 13 0.01% 0.01% 0.01% 0.01%

N – 15 0.00% 0.01% 0.00% 0.01%

N – 17 0.01% 0.02% 0.02% 0.02%

N – 21 0.76% 1.14% 0.94% 1.14%

N – 48a 0.57% 0.85% 0.70% 0.85%

N – 56a 4.80% 7.18% 5.91% 7.18%

N – 55 13.98% 20.90% 17.20% 20.90%

N – 56b 41.28% 61.72% 50.79% 61.72%

N – 53 5.46% 8.16% 6.72% 8.16%

N Sector Total 66.87% 100.00% 82.29% 100.00%

NNE – 28 1.02% 65.89% 1.26% 65.98%

NNE – 42 0.00% 0.15% Not Included Not Included

NNE – 57b 0.23% 15.14% 0.29% 15.17%

NNE – 52 0.24% 15.37% 0.29% 15.40%

NNE – 45 0.05% 3.45% 0.07% 3.45%

NNE Sector 

Total 1.55% 100.00% 1.90% 100.00%

NE – 12 0.00% 0.00% 0.00% 0.00%

NE – 29 0.63% 2.05% 0.77% 5.30%

NE – 37 0.02% 0.08% 0.03% 0.19%

NE – 47a 0.34% 1.11% 0.42% 2.87%

NE – 48b 18.73% 61.28% Not Included Not Included

NE – 46 1.20% 3.93% 1.48% 10.15%

NE – 43 0.52% 1.70% 0.64% 4.38%

NE – 47b 3.63% 11.87% 4.46% 30.65%

NE – 25 3.85% 12.60% 4.74% 32.53%

NE – 24 1.65% 5.39% 2.03% 13.91%

NE Sector Total 30.56% 100.00% 14.56% 100.00%

IET 10 Total 100.00% — 100.00% — 

* The affected sectors are 180 degrees from the direction from which the wind is blowing.
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From Table A-3, IET 10 run 56b contributes more than any other single run. According to 

RPRT-0079, Table 3-1, run 56b started on March 5, 1958, at 13:36 and ended on March 6, 1958, 

at 2:35; in other words, run 56b ran for 14 hours. Table A-4 presents the measured meteorology 

that was reported in RPRT-0079 during the run 56b release. Table A-4 shows that the wind was 

blowing toward the onsite worker locations during only one of the 14 hours of meteorological 

measurements. During run 56b, NIOSH conservatively assumed that all release occurred during 

the one hour the wind was blowing toward the worker’s location (i.e., from the North toward the 

South). However, the data from the hours before and after are toward the South and SSE, 

respectively; it seems unlikely that there would be two 180° shifts in the wind direction during a 

3-hour period. Also, the measured wind speed was 0 mph during the hour that the wind was

blowing toward the worker’s location. Since both the wind speed and direction are recorded as 

zero, this may be further indication that the meteorological data for that hour are unreliable.

For the remaining hours during run 56b, the wind was generally blowing from the South, away 

from the worker’s location. Also, the measured wind speed averaged 8 mph (including the 1 and 

0 mph measurements and excluding 8.6 mph), as opposed to the 6 mph used by NIOSH. Finally, 

the SC&A-calculated stability class is mostly D, with a single C, throughout run 56b. Similar 

results are expected if other IET 10 runs were to be evaluated to this level of detail.

Table A-4. IET 10 Run 56b Meteorology 

Release

Date

Release 

Time

Wind 

Speed

(mph)

Wind 

Speed 

(m/s)

Stability 

Class

Wind Direction

(degrees and 

sector) Worker Impacted?

3/5/1958 13 19 8.5 D 180° S No Impact

3/5/1958 14 14 6.3 C 202.5° SSW No Impact

3/5/1958 15 10 4.5 C 180° S No Impact

3/5/1958 16 6 2.7 D 157.5° SSE No Impact

3/5/1958 17 9 4.0 D 157.5° SSE No Impact

3/5/1958 18 9 4.0 D 157.5° SSE No Impact

3/5/1958 19 10 4.5 D 135° SE No Impact

3/5/1958 20 7 3.1 D 135° SE No Impact

3/5/1958 21 6 2.7 D 67.5° ENE No Impact

3/5/1958 22 10 4.5 D 90° E No Impact

3/5/1958 23 5 2.2 D 90° E No Impact

3/6/1958 0 4 1.8 D 180° S No Impact

3/6/1958 1 0 0.0 D 0° N Impact

3/6/1958 2 3 1.3 D 157.5° SSE No Impact

A.2. ATMOSPHERIC DISPERSION

For the RPRT-0079 analysis, NIOSH utilized a centerline atmospheric dispersion factor (X/Q) 

based on a single set of meteorological assumptions: i.e., a wind speed of 6 mph (2.7 m/s) and 

stability class E (slightly stable). In this section, SC&A examines the effects that these 

assumptions have on the X/Qs, and resulting radionuclide concentrations and receptor doses. 
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The X/Qs calculated by NIOSH are presented in RPRT-0079, Table 5-4, and have been 

reproduced here in Table A-5. The Class E X/Q values in Table A-5 are limiting at each location. 

NIOSH states that they only used the higher value (i.e., 7.68E-07 s/m3

) because the results are 

not “significantly different” and would result in a “slight overestimate” of some intakes, “but 

eliminates the need to determine where a worker was located onsite during the period for the IET 

#10 releases.” SC&A agrees with this approach.

Table A-5. NIOSH-Calculated Atmospheric Dispersion Factors, X/Q Values by 

Atmospheric Stability Class (s/m3) 

Area Class A Class B Class C Class D Class E Class F

ANL-W (TREAT), ICPP, 

TRA, SPERT (SPERT II), 

ARA (GCRE)

8.80E-09 1.68E-08 2.18E-08 2.10E-07 7.68E-07 1.11E-07

CFA, EBR-I, RWMC 6.01E-09 1.18E-08 1.55E-08 1.07E-07 5.37E-07 1.62E-07

Technical Area North Joint Frequency Table

Meteorological data are collected and organized into “joint frequency tables” that present the 

fraction of time that the data fall within a particular speed, stability class, and direction. For this 

analysis, SC&A focused on only wind speed and stability class. 

For the INL Technical Area North, PNL-10550, Environmental Settings for Selected U.S. 

Department of Energy Installations, Exhibit 6.3, provides the joint frequency distribution of 

atmospheric stability, wind direction, and wind speed (PNL 1995). Table A-6 summarizes the 

Pacific Northwest National Laboratory (PNNL) data for wind speed and direction only. Note that 

the joint frequency distribution should sum to 100%, but that the Table A-6 joint frequency sums 

to 105.1%. SC&A has checked that our transcription from Exhibit 6.3 is correct, so the problem 

is with PNL-10550, Exhibit 6.3. Table A-6 shows that the meteorological conditions of 2.7 m/s 

wind speed and stability Class E are met about 8.9% of the time. Table A-7 presents the joint 

frequency for the PNNL data only when the wind is blowing from the five sectors of interest for 

this study, i.e., NW, NNW, North, NNE, and NE. Table A-7 shows that the meteorological 

conditions of 2.7 m/s wind speed and stability Class E are met about 13.1% of the time. 

Table A-6. Idaho National Laboratory, Technical Area North – Joint Frequency 

Distribution of Atmospheric Stability and Wind Speed

Speed 

(m/s)

Stability 

Class A

Stability 

Class B

Stability 

Class C

Stability 

Class D

Stability

Class E

Stability 

Class F All

0.0–<1.6 0.065 0.009 0.008 0.017 0.014 0.105 0.217

1.6–<3.4 0.068 0.026 0.029 0.145 0.089 0.109 0.467

3.4–<5.6 0.000 0.012 0.029 0.111 0.036 0.000 0.188

5.6–<8.3 0.000 0.000 0.003 0.094 0.000 0.000 0.097

8.3–<11.0 0.000 0.000 0.000 0.057 0.000 0.000 0.057

>11.0 0.000 0.000 0.000 0.026 0.000 0.000 0.026

All 0.132 0.047 0.070 0.449 0.139 0.215 1.051

Source: PNL-10550, Exhibit 6.3
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Table A-7. TAN Joint Frequency Distribution of Atmospheric Stability and Wind Speed 

for NW, NNW, North, NNE, and NE Sectors 

Speed 

(m/s)

Stability 

Class A

Stability 

Class B

Stability 

Class C

Stability 

Class D

Stability 

Class E

Stability 

Class F All

0.0–<1.6 0.030 0.005 0.006 0.016 0.016 0.091 0.163

1.6–<3.4 0.025 0.014 0.025 0.190 0.131 0.124 0.508

3.4–<5.6 0.000 0.005 0.014 0.110 0.041 0.000 0.170

5.6–<8.3 0.000 0.000 0.002 0.077 0.000 0.000 0.079

8.3–<11.0 0.000 0.000 0.000 0.055 0.000 0.000 0.055

>11.0 0.000 0.000 0.000 0.025 0.000 0.000 0.025

All 0.055 0.024 0.046 0.473 0.187 0.215 1.000

SC&A utilized the NIOSH-supplied Excel file, “166017_INEL - IET 10 Releases and Worker 

Intakes Spreadsheet.xlsx,” to calculate the dispersion factors (X/Qs) at ANL-W (Transient 

Reactor Test Facility [TREAT]) for combinations of wind speeds and stability classes consistent 

with the PNL-010550, Exhibit 6.3, joint frequency table. Table A-8 shows the results of those 

calculations. Table A-9 shows the result of multiplying the values in Table A-7 with the 

corresponding values in Table A-8. 

Table A-8. Horizontal Centerline (H-CL) Dispersion Factors at ANL-W (TREAT)

Speed 

(m/s)

Stability 

Class A

Stability 

Class B

Stability 

Class C

Stability 

Class D

Stability 

Class E

Stability 

Class F

0.0–<1.6 2.97E-08 5.68E-08 7.37E-08 7.09E-07 2.59E-06 3.76E-07

1.6–<3.4 9.50E-09 1.82E-08 2.36E-08 2.27E-07 8.29E-07 1.20E-07

3.4–<5.6 5.28E-09 1.01E-08 1.31E-08 1.26E-07 4.61E-07 6.68E-08

5.6–<8.3 3.42E-09 6.54E-09 8.48E-09 8.16E-08 2.98E-07 4.33E-08

8.3–<11.0 2.46E-09 4.71E-09 6.11E-09 5.88E-08 2.15E-07 3.12E-08

>11.0 2.16E-09 4.13E-09 5.36E-09 5.16E-08 1.88E-07 2.73E-08

Table A-9. TAN Joint Frequency Weighted H-CL Dispersion at ANL-W (TREAT)

Speed 

(m/s)

Stability 

Class A

Stability 

Class B

Stability 

Class C

Stability 

Class D

Stability 

Class E

Stability 

Class F All

0.0–<1.6 8.78E-10 2.84E-10 4.14E-10 1.12E-08 4.14E-08 3.43E-08 8.84E-08

1.6–<3.4 2.39E-10 2.55E-10 5.81E-10 4.31E-08 1.08E-07 1.49E-08 1.67E-07

3.4–<5.6 0.00E+00 5.04E-11 1.86E-10 1.38E-08 1.88E-08 0.00E+00 3.29E-08

5.6–<8.3 0.00E+00 0.00E+00 1.33E-11 6.30E-09 0.00E+00 0.00E+00 6.31E-09

8.3–<11.0 0.00E+00 0.00E+00 0.00E+00 3.23E-09 0.00E+00 0.00E+00 3.23E-09

>11.0 0.00E+00 0.00E+00 0.00E+00 1.30E-09 0.00E+00 0.00E+00 1.30E-09

All 1.12E-09 5.90E-10 1.19E-09 7.89E-08 1.68E-07 4.92E-08 2.99E-07

The NIOSH-supplied Excel file, “166017_INEL - IET 10 Releases and Worker Intakes 

Spreadsheet.xlsx,” gives the ANL-W (TREAT) dispersion factor as 7.68E-07 sec/m3, whereas 

the TAN joint frequency weighted dispersion factor is 2.99E-07 sec/m3. Similar results are 

expected for the other dose receptor locations included in the NIOSH RPRT-0079 analysis. 
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ORAUT-RPRT-0079, Attachment A 

RPRT-0079, Attachment A, provides meteorological data collected at the INL Central Facilities 

Area (CFA) and TAN during the IET 10 test period from December 20, 1957, to March 6, 1958. 

Attachment A provides wind speed and directions data and was used to determine which IET 10 

runs to include in the analysis (see Section A.1). Although Attachment A does not provide 

stability class data, it does provide the temperature measured at two different heights, which can 

be used to estimate stability class (see Table A-10). This allows for an IET 10-specific joint 

frequency table to be formed from the Attachment A data, as shown in Table A-11. Table A-12 

shows the result of multiplying the values in Table A-8 by the corresponding values in 

Table A-11. 

Table A-10. Relationship Between Delta Temperature and Stability Class

Pasquill 

Class

Delta T/Delta Z 

(°C/100 m)

A -1.9

B -1.9 to -1.7

C -1.7 to -1.5

D -1.5 to -0.5

E -0.5 to 1.5

F 1.5 to 4.0

G >4.0

Source: NOAA 2017.

Table A-11. Joint Frequency Distribution of Stability Class and Wind Speed for 

IET 10 Runs

Speed 

(m/s)

Stability 

Class A

Stability 

Class B

Stability 

Class C

Stability 

Class D

Stability 

Class E

Stability 

Class F

Stability 

Class G All

0.0–<1.6 0.0000 0.0000 0.0379 0.2385 0.0892 0.0546 0.0654 0.4857

1.6–<3.4 0.0005 0.0027 0.0422 0.1833 0.0568 0.0330 0.0254 0.3440

3.4–<5.6 0.0000 0.0000 0.0173 0.0481 0.0043 0.0022 0.0000 0.0719

5.6–<8.3 0.0000 0.0000 0.0103 0.0422 0.0016 0.0000 0.0000 0.0541

8.3–<11.0 0.0000 0.0000 0.0022 0.0195 0.0005 0.0000 0.0000 0.0222

>11.0 0.0000 0.0000 0.0011 0.0195 0.0011 0.0005 0.0000 0.0222

All 0.0005 0.0027 0.1109 0.5511 0.1536 0.0903 0.0909 1.0000
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Table A-12. IET 10 Joint Frequency Weighted H-CL Dispersion at ANL-W (TREAT)

Speed 

(m/s)

Stability 

Class A

Stability 

Class B

Stability 

Class C

Stability 

Class D

Stability 

Class E

Stability 

Class F* All

0.0–<1.6 0.00E+00 0.00E+00 2.79E-09 1.69E-07 2.31E-07 4.51E-08 4.48E-07

1.6–<3.4 5.14E-12 4.92E-11 9.94E-10 4.16E-08 4.71E-08 7.02E-09 9.67E-08

3.4–<5.6 0.00E+00 0.00E+00 2.27E-10 6.07E-09 1.99E-09 1.45E-10 8.43E-09

5.6–<8.3 0.00E+00 0.00E+00 8.71E-11 3.44E-09 4.84E-10 0.00E+00 4.01E-09

8.3–<11.0 0.00E+00 0.00E+00 1.32E-11 1.14E-09 1.16E-10 0.00E+00 1.27E-09

>11.0 0.00E+00 0.00E+00 5.79E-12 1.00E-09 2.04E-10 1.48E-11 1.23E-09

All 5.14E-12 4.92E-11 4.12E-09 2.22E-07 2.81E-07 5.23E-08 5.60E-07

* The Class G frequencies have been included with Class F, because “the criteria for class G are 

approximations that do not have an explicit basis in Pasquill’s methodology” (SRNL-STI-2012-00055, page 6).

The NIOSH-supplied Excel file, “166017_INEL - IET 10 Releases and Worker Intakes 

Spreadsheet.xlsx,” gives the ANL-W (TREAT) dispersion factor as 7.68E-07 sec/m3, whereas 

the TAN joint frequency weighted dispersion factor is 5.60E-07 sec/m3

. Similar results are 

expected for the other dose receptor locations included in the NIOSH RPRT-0079 analysis. 

Horizontal Off-Centerline

The equation used to calculate atmospheric dispersion for RPRT-0079 is given by NIOSH as: 

Χ/Q = (2 π σY σZ u)-1 exp[-1⁄2 (y/σY)

2

] {exp[-1⁄2 ((z-H)/σZ)

2

] + exp[-1⁄2 ((z+H)/σZ)

2

]}

The exponential term “exp[-1⁄2 (y/σY)

2

]” accounts for the receptor being off the horizontal 

centerline of the plume. For all RPRT-0079 dispersion factors, NIOSH assumed that y = 0 m, 

i.e., that the dose receptor is located on the plume’s horizontal centerline. In this section, SC&A 

investigates the effect of the dose receptor being located off the horizontal centerline.

Figure A-2 shows the results of solving only the exponential term exp[-1⁄2 (y/σY)

2

] for the six 

stability classes.
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Figure A-2. Horizontal Off-Centerline Dispersion Reduction Factor

As shown in Figure A-2, the largest dispersion factor reduction occurs for stability Classes D and 

E. Table A-9 shows that about 44.9% and 13.9% of the time the TAN meteorology is measured 

in those classes. Likewise, Table A-11 shows that about 55.1% and 15.4% of the time during the 

IET 10 runs, the dispersion classes were in Class D and Class E, respectively.

As discussed in Section A.1, in the release calculation NIOSH included all IET 10 releases that 

were directed toward the SE to SW sectors. Figure A-2 shows that it is highly unlikely that an 

individual located in one sector would receive exposure to a plume travelling in an adjacent (or 

further away) sector. What this means is that an individual continuously occupying a downwind 

location would only be exposed to releases that occurred when the wind was blowing toward that 

location, and that using the total release as calculated by NIOSH would overestimate the 

individual’s exposure. 

Table A-2 shows the SC&A-calculated wind direction IET 10 releases. It can be used to estimate 

the conservatism of using the entire NIOSH-calculated release for all locations.

Vertical Centerline

NIOSH gives the equation used to calculate atmospheric dispersion for RPRT-0079 as: 

Χ/Q = (2 π σY σZ u)-1 exp[-1⁄2 (y/σY)

2

] {exp[-1⁄2 ((z-H)/σZ)

2

] + exp[-1⁄2 ((z+H)/σZ)

2

]}

The exponential term “{exp[-1⁄2 ((z-H)/σZ)

2

] + exp[-1⁄2 ((z+H)/σZ)

2

]}” accounts for the receptor 

being vertically off the centerline of the plume. In this term, H and z represent the heights of the 
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release and dose receptor, respectively. For all RPRT-0079 dispersion factors, NIOSH assumed 

that the releases occurred at a height of 47.5 m (i.e., a 150-foot stack) and assumed a receptor 

height of 1.7 m. When these two parameters are set to zero, the resulting dispersion factors are 

calculated at the plume’s vertical centerline. On the NIOSH-supplied Excel file, “166017_INEL 

- IET 10 Releases and Worker Intakes Spreadsheet.xlsx,” SC&A set these parameters to zero, 

and the resulting X/Qs are shown in Table A-13. 

Table A-13. Vertical and Horizontal Centerline Dispersion Factors, X/Q Values by 

Atmospheric Stability Class (s/m3) 

Area Class A Class B Class C Class D Class E Class F

ANL-W (TREAT), ICPP, 

TRA, SPERT (SPERT II), 

ARA (GCRE)

8.80E-09 1.68E-08 2.18E-08 2.11E-07 8.73E-07 2.70E-06

CFA, EBR-I, RWMC 6.01E-09 1.18E-08 1.55E-08 1.07E-07 5.91E-07 1.90E-06

The NIOSH-supplied Excel file, “166017_INEL - IET 10 Releases and Worker Intakes 

Spreadsheet.xlsx,” gives the highest dispersion factor as 7.68E-07 sec/m3 and is associated with 

Class E (see Table A-5), whereas the highest vertical centerline dispersion factor is 

2.70E-06 sec/m3 and is associated with Class F.

Sector Average

The equation given above is usually used to calculate dispersion of short time periods, e.g., from 

hours to days following an episodic release. When releases occur over long periods of time, the 

long-term or annual average values of X/Q is calculated via Regulatory Guide 1.111, Revision 1, 

Methods for Estimating Atmospheric Transport and Dispersion of Gaseous Effluents in Routine 

Releases from Light-Water-Cooled Reactors, Equation 3 (NRC 1977): 

Χ/Q = 2.032 fij (x ui σZj)

-1 exp[-((z-H)2

/(2σZj

2

)]

The above equation assumes a continuous release and that the resulting effluent concentrations 

would be distributed evenly across a 221⁄2° direction sector. Using the above equation, SC&A 

calculated the sector average dispersion factor for each INL area analyzed by NIOSH; Table A-4 

provides the results.

Table A-14. Sector Average Dispersion Factors, X/Q Values by Atmospheric Stability Class 

(s/m3) 

Area Class A Class B Class C Class D Class E Class F

ANL-W (TREAT) 1.28E-08 1.28E-08 1.28E-08 3.64E-08 2.52E-07 7.16E-08

ICPP 1.02E-08 1.02E-08 1.02E-08 2.90E-08 2.01E-07 5.70E-08

TRA 1.01E-08 1.01E-08 1.01E-08 2.89E-08 2.00E-07 5.68E-08

SPERT (SPERT II) 1.02E-08 1.02E-08 1.02E-08 2.90E-08 2.00E-07 5.69E-08

ARA (GCRE) 9.77E-09 9.77E-09 9.77E-09 2.79E-08 1.93E-07 5.48E-08

CFA 9.14E-09 9.14E-09 9.14E-09 1.83E-08 1.59E-07 8.91E-08

EBR-I 8.11E-09 8.11E-09 8.11E-09 1.62E-08 1.42E-07 7.91E-08

RWMC 7.75E-09 7.75E-09 7.75E-09 1.55E-08 1.35E-07 7.55E-08
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The first thing to notice about Table A-14 is that the dispersion factors differ for each location. 

This is because the distance to the location is included in the calculation (see “x” in the above 

equation). The second is that the sector average X/Q is the same for Classes A, B, and C. This 

occurs because the sigma-z value was limited to 2,000 m, and the graph did not depict sigma-z 

values for these classes beyond a distance of 5,500 m.

The NIOSH-supplied Excel file, “166017_INEL - IET 10 Releases and Worker Intakes 

Spreadsheet.xlsx,” gives the highest dispersion factor as 7.68E-07 sec/m3 and is associated with 

Class E (see Table A-5), whereas the highest sector average dispersion factor is 2.52E-07 sec/m3

and is associated with Class F.

The above analyses demonstrate that overall, the approach used by NIOSH to derive atmospheric 

dispersion factors at potential locations of onsite workers outdoors is extremely claimant 

favorable.