ORAU Team

NIOSH Dose Reconstruction Project

Technical Basis Document for the Hanford Site - Occupational 

Environmental Dose

Document Number: 

 ORAUT-TKBS-0006-4 

Effective Date: 10/15/2003

Revision No.: 00

Controlled Copy No.: ________

Page 1 of 33

Subject Expert: Noel Savignac

Approval: Signature on File_____________ Date:10/15/2003

Edward D. Scalsky, Document Owner

Approval: Signature on File_____________ Date: 10/15/2003

Judson L. Kenoyer, Task 3 Manager

Concurrence: Signature on File__________ Date: 10/19/2003

Richard E. Toohey, Project Director

Approval: Signature on File__________ Date:10/16/2003

James W. Neton, OCAS Health Science Administrator

Supersedes:

None

TABLE OF CONTENTS

Section

Record of Issue/Revisions ................................................................................................................... 3

Page

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

4.1 Occupational Environmental Dose .............................................................................................. 5

4.2 Doses from OnSite Atmospheric Radionuclide Concentrations ................................................... 6

4.2.1 On-Site Releases to Air................................................................................................... 7

4.2.2 Environmental Air Monitoring......................................................................................... 16

4.2.3 Intake of Airborne Radionuclides................................................................................... 16

4.3 External Dose ...........................................................................................................................20

4.3.1 Ambient Radiation ......................................................................................................... 20

4.3.2 Releases of Noble Gases.............................................................................................. 25

4.3.3 Skin Deposition of Airborne Particulate Emissions ........................................................ 26

4.4 Uncertainties .............................................................................................................................28

References ........................................................................................................................................30

Glossary .........................................................................................................................................33
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 3 of 33

LIST OF TABLES

Table

Table 4.2-1. Facilities operations dates.........................................................................................7 

Page

Table 4.2.1-1. Estimated release rates from Hanford reactors and air pathway screening

 factors for 41Ar, 3

H, and 14C........................................................................................8

Table 4.2.1-2. Physical, chemical, and radiological properties of radioactive particles released

 from Hanford, 1945-1956...........................................................................................9

Table 4.2.1-3. Annual amount of tritium released from 108-B.........................................................16

Table 4.2.3-1. Selected receptor locations with identifying computational nodes............................20

Table 4.3.1-1. External gamma radiation at Hanford (mrem/yr).......................................................23

Table 4.3.2-1. Distributions of monthly release estimates for 41Ar from reactors and areas...........26

Table 4.3.2-2. Argon-41 concentrations measured in and effluent flow rates for production reactor 

stacks........................................................................................................................26

Table 4.3.3-1. Expected Number of Particle Encounters for REDOX Plant Emissions during the 

 Early 1950s assuming a use factor of 0.1.................................................................27

Table 4.3.3-2. Dose coefficients for radionuclides contained in Hanford active particles................27

LIST OF FIGURES

Figure

Figure 4.1-1. Locations of potential exposure for which intakes and exposures are provided..........6

Page

Figure 4.2.1-1. Average fuel cooling times prior to processing at Hanford...........................................7 

Figure 4.2.1-2. Estimated distributions of physical and aerodynamic diameters for large

 “active particles” together with estimated distributions for particle surface area

 and activity.................................................................................................................12

Figure 4.2.1-3. Estimated releases of 144Ce from T Plant.................................................................13

Figure 4.2.1-4. Estimated releases of 131l from T Plant. Heeb (1994) and Napier (2002)

 provided estimates.....................................................................................................13

Figure 4.2.1-5. Estimated releases of 239Pu from Z Plant.................................................................14

Figure 4.2.1-6. Estimated releases of 106Ru from REDOX Plant......................................................15

Figure 4.3.1-1. Radiation levels measured by detachable C chambers at two locations on the

 Hanford Site, 1945-1948.............................................................................................21

Figure 4.3.1-2. Exposure rates measured near the REDOX Plant and at four military

 Installations.................................................................................................................22

Figure 4.3.1-3. Time trends in annual 131l and 106 Ru releases to air and net exposure rates

 Between the 200 Areas (Building 622) and at the REDOX plant perimeter................22

 
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 3 of 33

RECORD OF ISSUE/REVISIONS

ISSUE 

AUTHORIZATION 

DATE

EFFECTIVE 

DATE

REV. 

NO. DESCRIPTION

Draft 09/15/2003 00-A New document to establish Occupational 

Environmental Dose Section 4. Initiated by 

Edward D. Scalsky.

10/15/2003 10/15/2003 00 First approved issue. Initiated by Edward D. 

Scalsky.
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 4 of 33

ACRONYMS AND ABBREVIATIONS

Bq Becquerel

Ci Curie

PUREX Plutonium Uranium Extraction

REDOX Reduction Oxidation
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 5 of 33

4.1 OCCUPATIONAL ENVIRONMENTAL DOSE 

The occupational environmental dose is the dose received by individuals while outside of operational 

facilities onsite such as process buildings, chemical separations plants, reactors or other structures at 

Hanford. Their internal dose from the inhalation of radioactive materials may be determined from 

radionuclide air concentrations. Their external dose to radioactive materials outside their bodies may 

be determined from immersion in a cloud of inert gases, from deposition of particles on the skin, or 

from adjacent operational facilities. This section of the Technical Basis Documents provides the 

rational and/or historic background information and data for the reconstruction of occupational 

environmental doses for unmonitored personnel at the Hanford Site.

The four chemical separations plants, T Pant, B Plant, REDOX Plant and the PUREX plant, along with 

the plutonium handling Z plant are shown in Figure 4.1.1 to be the most important release points at 

Hanford. Section 4.3.2 showed that 41Ar from the reactors was also an important source of worker 

exposure. For individuals working outside process buildings and facilities at Hanford, pathways of 

concern are:

• the inhalation of radionuclides in the air, 

• direct external radiation from plumes, 

• physical contact with particulate radionuclides incident on the skin. 

Construction workers, contractors, security guards, environmental monitoring personnel, and 

personnel involved with outdoor work duties would be the personnel likely to receive occupational 

environmental doses. 

The Hanford Site atlas (http://www.bhierc.com/dm/hgis/hgis.htm) and Gerber (1992) show the location 

of the Hanford Camp, Columbia camp, and other locations where individuals worked and lived. For 

example up to 40,000 individuals, mainly construction workers, resided at Hanford Camp until it was 

closed in February 1945. Details on the buildings and facilities at the Hanford site are provided in 

Gerger (1993). Figure 4.1-1 shows many of these locations which were selected as locations where 

annual intakes of radionuclides in air were determined.
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 6 of 33

Figure 4.1-1. Locations of potential exposure for which intakes and exposures are 

provided.

4.2 DOSES FROM ONSITE ATMOSPHERIC RADIONUCLIDE CONCENTRATIONS

In 1943 the Hanford site was selected as the location to produce plutonium for the U.S. atomic 

weapons program (Groves 1962). A total of nine reactors, four chemical separations plants, and a 

plutonium handling plant became operational at the site in the following years (Ballinger and Hall 

1991; Gydesen 1992; Till et al. 2002). The dates of operation of these facilities are presented in 

Table 4.2-1.

The plutonium produced in the reactor fuel elements was extracted from the irradiated fuel in the 

chemical separations plants (T, B, REDOX, and PUREX) and converted to metallic plutonium in the Z 

plant. Throughout operations of the reactor, the chemical separations plants, and the Z plant a 

portion of the radionuclides being processed was released into the atmosphere and transported 

primarily in the downwind direction towards the northeast (Farris et al. 1994).
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 7 of 33

Table 4.2-1. Facilities operation dates.

Reactor Dates of Operation

Chemical Separations 

Plants Dates of Operation

100-B 1944–1968 T 1944–1952

100-D 1944–1967 B 1945–1956

100-F 1945–1965 REDOX 1952–1966

100H 1949–1965 PUREX 1956–1992

100-DR 1950–1964

100-C 1952–1969 Pu Handling Plant

100-KE 1955–1971 Pu Handling Plant

100-KW 1954–1970

100-N 1963–1987 Z 1945–1976

4.2.1

Figure 4.2.1-1 illustrates the “fuel element cooling time” which is the elapsed time between discharge 

of the fuel elements from the reactors and the start of fuel processing in the chemical plants. Between 

1944 and 1945 the fuel element cooling time was approximately 40 days. By 1947 the cooling time 

was extended to approximately 90 days. The shorter cooling time resulted in the releases of larger 

quantities of volatile, short-lived radionuclides compared to later years. For example in 1945 up to 

90,000 Curies of 131I were released each month compared to 10,000 Curies per month after 1946. 

Since there was no filtration to limit release of the volatile radionuclides in the early days, the releases 

to the atmosphere in 1945 were the largest at any time at Hanford (Till et al. 2002). 

On-Site Releases to Air

0

20

40

60

80

100

Average cooling time (days)

Date

Dec

1944

Nov

1945

Nov

1946

Nov

1947

Figure 4.2.1-1. Average fuel cooling times prior to processing at 

Hanford.
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 8 of 33

Heeb (1994) published the releases of 41Ar, 14C, and 3

H from the reactors based on historical 

measurements. Screening studies eliminated from dose consideration 3

H and 14C releases to the 

atmosphere from the reactors based on the product of the amount released and the dose conversion 

factors shown in Table 4.2.1-1. The estimated dose contribution of 41Ar was 10,000 times greater 

than that of 3

H and 3000 times greater than that of 14C. However due to the large 3H release from the 

108-B facility the dose from 3

H was assessed. (See the subsequent section on “Release of Tritium for 

108-B.” See also section 4.3.2 for additional information on 41Ar.

Table 4.2.1-1. Estimated release rates from Hanford reactors and air pathway 

screening factors for 41Ar, 3

H, and 14C. 

Radionuclide

Estimated release 

from all reactors 

(Bq d–1)

a

Screening factor for inhalation 

and direct radiation exposure 

(Sv per Bq m–3)

b

41Ar 1.5 × 1013 1.5 × 10–6

3

H 5.2 × 1010 1.4 × 10–7

14C 4.8 × 109 4.5 × 10–6

a. Release estimates from Heeb (1994)

b. Screening factors from Appendix B of 

. 

NCRP (1996)

Similar screening of the radionuclides released demonstrated that the dose from the following 

radionuclides should be considered (Till et al. 2002): The assumed absorption type is presented for 

each radionuclide.

. 

Radionuclide 41Ar naAbsorption Type

3

H water

 gas (HT or T2) submersion

131I Class SR-1, Type F

144Ce144Pr M all compounds except oxides, hydroxides and fluorides

 S oxides

137Cs F all compounds

239Pu S 

103Ru103Rh S 

106Ru106Rh S 

90Sr90Y F all compounds except

 S Strontium titanate (SrTiO3) 

95Zr95Nb F all compounds except

 M oxides, hydroxides, halides, and nitrates

 S carbides

S = Slow absorption

M = Moderate absorption

F = Fast absorption

Radionuclides listed in pairs are parents with associated short-lived progeny. These are assumed to 

be in equilibrium in the environment. Source terms are release rates of radioactive materials at 

specific locations. The source terms for the reactors, chemical separations plants and the plutonium 

handling plant are presented in Attachments A-1 through A-9. 
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 9 of 33

Table 4.2.1-2. Physical, chemical, and radiological properties of radioactive particles released from Hanford, 1945–1956. Interval Source 

report Location of sample Physical characteristics

Chemical 

Beginning Ending characteristics Radiological characteristics

May 7, 1945 HW-3-2894

Stack samples taken 

from the T Plant 

0.6–0.8 MeV beta presumably from 

iodine; also 1.5–2.0 MeV beta

1945 1947 HW-10758 Vegetation, processing 

plant effluent air, and 

ambient air

Total beta 7 nCi per filter

April 1947 HW-11082 Outside near T Plant 

fence

Presence of singular large particles 

not indicated

Mostly Ce and decay product, Pr

April 1947 HW-55569 Outside in 200 Areas Effective half-life of about 300 days. 

Principal contaminants were (in order): 

Ce, Y, Sr, Ru, Cs.

Fall 1947 HW-7865 Outside ground near T, 

B Plants

Can be mechanically separated from 

dirt

Total beta activity ranging from 0.5 μCi 

to 1 μCi. Most of the beta activity was 

Ce; most alpha was Pu (range 0.07–

1.7 nCi)

Fall 1947 HW-9259 Outside ground near T, 

B Plants

Color reddish brown; carrier particles 

>100 μm, range 20 to 1500 μm linear 

dimensions; small particles, mists, 

and droplets emitted since 

operations began 

Contain iron oxides; 

can be separated with 

magnets

Alpha activity mostly Pu, 1/20 as much 

U. Beta activity correlated with surface 

area of particle; mostly Ce (and 

daughter Pr-144), Y, Sr, Ru, and Cs

April 1947 HW-7920 Outside ground near T, 

B Plants

Mass of 0.1 to 1 mg; brown color

(different from soil)

0.1 μCi to 1 μCi. T Plant particles 60–

90% Ce and up to 15%Y. B Plant 30–

55% Ce, 7–20%, Sr and 30–45% Y

April 1947 April 1948 HW-8624 Outside ground near T, 

B Plants

Physical sizes of 153 large particles 

ranged from 40 μm to >1 mm.

Median 300 μm. No reliable data on 

very small particles.

Essentially all 

particles contain 

enough iron to be 

separated 

magnetically 

0.0001 to 3 μCi. 30–50% Ce; 10–50% 

Y; 10–20% Sr

~March 1948 HW-9175 Processing plant 

effluent

Some are <1 μm 

Spring 1948 HW-9864 Processing plant 

effluent

Mists mean size <5 μm; magnetic 

specks, density of iron

Spring 1948 HW-10261 Ground and roofs 

surrounding processing 

plants

Usually less than 500 μm; range 20–

1500 μm 

High in iron; low 

carbon and calcium

2.5 pCi to 3.2 μCi beta per particle. Max 

beta energy 3.0 MeV 

Spring 1948 HW-10261 Processing plant 

effluent

Beta mostly Ce; alpha mostly Pu

~April 1948 Gregg 1948 Outside ground 10–1000 μm Associated with rust Max 3 μCi beta per particle

April 1948 April 1948 HW-12677 Particles collected by 

air samplers

1–10 pCi fission products per particle

April 1948 April 1948 HW-12677 Stacks of 314 Building, 

the Melt Plant, in 300 

Area

Mostly uranium

? 1950 HW-15802 Ventilation air of the B 

Plant before sand filter

100% of alpha was Pu; most of beta 

was Ce, rare earths, Ru, Zr, Y, and Sr

April 3, 1952 HW-33068 On survey meter inside 

car with window open

Particle read 40 rad h−1
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 10 of 33

April 29, 1952 Eastern and northern 

sections of the REDOX 

area

From 100 cpm at 1 in. to 800 mrad h−1

at surface; gross beta activity ranged 

up to 0.1 μCi per sample

April 1952 June 1952 HW-26493 Particles emitted from 

REDOX Plant (second, 

third, and fourth 

episodic releases on 

April 3, April 29, and 

June 24)

Ranged from microscopic translucent 

hydroscopic crystals adhering to the 

soil sand, to visible chalky particles 

varying in shape and size—a few 

with diameter ~ 1⁄2 in. Larger visible 

particles easily fractured, apparently 

a conglomerate of microscopic 

crystals. 

Chemically, the 

composition of the 

inactive material was 

mainly ammonium 

nitrate with a small 

amount of occluded 

dust particles

90 to 98% of the total beta activity was 

Ru; 131I in particulate contamination 

ranged from 1–5%. Beta particle 

activity varied in direct relationship with 

size.

June 24, 1952 HW-32473 Outside: flakes from 

fourth episodic release 

from REDOX

1/64–1/32-in. thick and up to several 

inches in diameter. Large flaky 

radioactive particles found near the 

eastern REDOX exclusion area 

rapidly disappeared, though activity 

spots were detectable with survey 

instruments. Flakes fragile and 

hydroscopic.

Carrier crystal was 

predominately 

ammonium nitrate 

Mostly ruthenium

March 12, 1953 HW-28009 Ambient air near 

REDOX

36% of beta activity was Ru, 43% rare 

earths and Y

Spring 1953 HW-28780 Base (inside) of the 

REDOX stack 

Median particle size about 0.2 μm 

with GSD of 1.6 during one sample 

and 2.5 during another 

Activity median particle size was 0.6 

microns.

August 7, 

1953

August 14, 

1953

HW-29346 

HW-32473

Outside ground 

southeasterly direction 

from the REDOX stack

Up to 5 in. (13 cm); average 0.5 in. 

(1.3 cm); up to 1/2 to 3⁄4-in. thick

Carrier crystals were 

ammonium nitrate

Max 15 rep h−1; average 300–500 mrep 

h−1 surface. 70% Ru, 25% rare earths 

and Y, and trace amounts of Sr, Ba, 

and Zr. 

December 

1953

HW-32209 Air entering sand filter 

of REDOX

Two cascade impactor sample 

results geometric mean of 0.3 μm 

(GSD 2.8) and 0.5 μm (GSD 3.2); 

average particles per cubic meter 

was 5.3 × 108

December 

1953

HW-32209 Air at 10-ft level inside 

REDOX stack

Four cascade impactor sample 

results ranged from geometric 

median size 0.3 μm (GSD 2.0) to 0.4 

μm (GSD 3.8); average particles per 

cubic meter, 2.4× 108

August 9, 

1954

May 18, 1954 HW-33896 Air entering REDOX 

Plant sand filter

92% of total beta activity was Ru in 

March; in May, 24% was Ru, 28% rare 

earths, 14% Zr, and 25% Nb

HW-33068 General review: input 

side of process sand 

filter

Less Ru (80%) and more of the rare 

earths (10–15%) and Sr (1–2%), 

compared to particles emitted to the 

environment.
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 11 of 33

1952 1954 HW-33068 General review: 

REDOX releases to 

environment

Primary particles about 2 μm; large 

secondary particles typically 100 μm.

Carrier base is 

aggregate of 

ammonium nitrate, 

sometimes sand. 

Inhalable particles 

were between 40–

80% soluble after 36 

h in simulated lung 

fluid. Large particles 

were 3– 70% soluble 

after 48 h in simulated 

gastric juice.

Primary particles up to 5 nCi per 

particle, dose rate of 0.5 mrad h−1

; 

secondary particles dose rates up to 

20 rad h−1 and 200 μCi per particle. Ru 

and Rh activity 98% of the total, with 

Sr-89 and Sr-90 <0.3%; rare earths 

plus Y <1.0%; and Zr-95 <0.5%. 

June 1954 HW-32473 Outside ground in 200 

Areas

No well-defined relationship between 

particle size and dose rate. Particles 

of several thousand square μm were 

observed. Easily fractured.

Ammonium nitrate 

present

90% of beta activity was Ru; activity 

ratio 103:106 was 0.6 to 1.4; one 

particle with dose rate of 1.2 rad h−1

contained 6.3 μCi; another reading 

120 mrad h−1 had 0.49 μCi; average 

dose rate per μCi was about 200 mrad 

h−1

 

November 7, 

1954

HW-36505 Five particles emitted 

from REDOX stack

Four of the particles were 

agglomerates of smaller white 

crystals with yellow discoloration on 

some surfaces. One particle was 

bright yellow without the crystalline 

appearance.

Ammonium nitrate 

and iron were found 

in four particles. The 

bright yellow particle 

was mostly calcium 

and iron.

95% of the beta activity was from 

Ru/Rh isotopes with the ratio of activity 

of 103Ru to 106Ru being less than 0.05. 

Also Sr, rare earths, Zr, Pu.

October 1954 December 

1954

HW-36504 Ground surfaces 

around REDOX

Maximum dimensions ranging from a 

few μm to ~1000 μm

Nearly all beta was Ru/Rh; Ru-103:Ru106 ratio less than 1

December 

1954

HW-35542 Ground surfaces 

around REDOX

Relative to a unit length, the average 

width was 0.75 +/− 0.14 and the 

depth was 0.39 +/− 0.18. The density 

is believed to be about 1.5

May 29, 1956 June 4, 1956 HW-44215 Outside of U Plant in 

200-West Area

Large paint flakes up to 8 in. long, 

peeled off duct work between sand 

filter and U Plant stack

Associated with 

painted stack liner

Alpha and beta
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 12 of 33

Routine Releases from T and B Plants

Stack releases to the environment under normal operating conditions at the chemical separations 

plants were proportional to the rates at which the material entered the plant as irradiated fuel from the 

reactors. The most likely source of these releases was iron oxide particulates from corroding ductwork 

in the ventilation systems of the T and B plants. Analysis of the particles indicated that the 

radionuclides were deposited on the blowers and other iron surfaces and were released into the 

ventilation air stream as the iron parts corroded. Figure 4.2.1-2 presents the estimated distributions of 

physical, aerodynamic, and radiological properties of the released particles. Other physical 

characteristics of the particles and their distributions are reported in HW-7865, HW8624, HW-9175, 

and HW-10261. (See also Table 4.2.1-2)

10

100

1000

10000

.1 1 5 10 20 30 50 70 80 90 95 99 99.9

Percentile

Diameter (μm)

Particle Activity (μCi)

10

1

0.1

0.01

Activity

Surface

Area

Physical

Aerodynamic

Figure 4.2.1-2. Estimated distributions of physical and aerodynamic 

diameters for large “active particles” together with estimated 

distributions for particle surface area and activity. (Till et al. 2002).

For routine releases from T and B plants the estimated monthly release is the product of the following 

factors: 

• The monthly processing rates for each radionuclide compiled by Heeb (1994) which are the 

rates at which the radionuclide enter the separation plants as irradiated fuel from the reactors. 

The processing rates were estimated by Heeb (1994) for 90Sr, 103Ru, 106Ru, 131I, 144Ce, and 

239Pu and by Till et al. (2002) for 137Cs.

• The release fraction which is the ratio of the rate that the radionuclide was released to the 

processing rate of that radionuclide.

• The effluent treatment modifier which accounted for increased release rates in the early years 

of operation of T and B plant when there were no scrubbers or filters on the effluents. 

• Uncertainty factors related to processing rates and the amount of radioactive decay that 

occurred between fuel irradiation and fuel processing.
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 13 of 33

Figures 4.2.1-3 and 4.2.1-4 illustrate the releases of 144Ce and 131I from T plant. 

Effluents from B plant were similar to those from T plant but were higher due to difficulties 

encountered with the effluent filtration and scrubber system. 

10-1

100

101

102

103

104

95th %-ile

GM

Estimated monthly releases (GBq) of 144Ce from T Plant

Year

1945 1947 1949 1951 1953 1955

Estimated

release (Ci)

270

27

2.7

0.27

0.027

Figure 4.2.1-3. Estimated releases of 144Ce from T Plant. 

(Till et al. 2002).

101

102

103

104

105

106

107

Estimated median monthly release (GBq)

Year

1945 1947 1949 1951 1953 1955

Estimated

release (Ci)

270

2700

27000

27

2.7

0.27

Figure 4.2.1-4. Estimated releases of 131I from T Plant. 

Heeb (1994) and Napier (2002) provided estimates. 

(Till et al. 2002). 
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 14 of 33

Routine Releases of Plutonium from Z Plant

Z plant was not one of the chemical separations plants but was located in the 200-W area of Hanford. 

Z plant produced and fabricated metallic plutonium from plutonium nitrate that came from the 

chemical separations plants. 239Pu was released as small particles usually less than 1 μm. Figure 

4.2.1-5 presents the estimated annual releases of 239Pu from Z plant as median estimates and the 95th

percentiles of the distribution. 

101

102

103

104

GM

95th %-ile

Year

1949 1951 1953 1955 1957 1959 1961

Estimated monthly release (MBq)

Estimated

release (mCi)

0.27

2.7

27

Figure 4.2.1-5. Estimated releases of 239Pu from Z Plant. (Till et 

al. 2002).

Routine Releases of Iodine from the Chemical Separations Plants

131I was released from the four chemical separations plants, T, B, REDOX, and PUREX from 1946 

until 1962. Screening calculations indicate that 131I was the most important radionuclide conveying 

dose to people on site (Till et al., 2002). Heeb 1994, Warren 1961, Junkins et al. 1960 and Foster 

and Nelson 1961 reported estimates of the 131I releases. The estimates were complicated by different 

reported fuel element cooling times for the same fuel elements, unusual releases not included in the 

release estimates such as a boil-over and a fire in a dissolver, the presence of organic halides that 

were not included in the estimates, and unaccounted for plateout of elemental iodine in the sampling 

systems. The estimates of 131I releases for T plant are presented in Figure 4.2.1-4. The estimates 

were compiled by Till et al. (2002) based on the amount of iodine in the fuel elements sent to the 

dissolvers of the chemical separations plants (Heeb, 1994) and the stack monitoring data and 

environmental measurements (Napier 2002). The absorption types for all compounds of iodine is F 

and is assumed to be a class SR-1 vapor for internal dose calculations.
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 15 of 33

Non-routine Releases from the REDOX Plant

Ammonium nitrate flakes formed on the inside of the exhaust stack of the REDOX plant and were 

released in 1952 through 1954. The largest release occurred in 1954. The flakes formed from the 

mixture of ammonia and nitrous oxides in the ventilation air. Volatile ruthenium oxide, RuO4, formed 

in an oxidation step in the plant, combined with the ammonium nitrate to form the flakes containing 

103Ru and 106Ru. Some of the flakes were up to 10 cm diameter, contained up to 200 μCi (7.4E6 Bq) 

of ruthenium, and produced surface contact dose rates up to 20 rad/hour. (1 Ci = 3.7 x 1010 Bq). 

Physical characteristics of the particles are reported in HW-28780, and HW-33061. Contact dose 

rates for 65.5% of the particles were in the 5-50 mrad/hr range. The maximum deposition density 

occurred within about 400 m of the stacks and was 2-5 particles per 100 m2 (Parker 1956, HW33068). These releases exposed military and other personnel onsite (Johnson 1954).

Table 4.2.1-2 is a summary of the physical, chemical, and radiological properties of radioactive 

particles released from Hanford 1945-1956 and includes releases from T, B, and REDOX plants; 

Figure 4.2.1-6 presents the monthly 106Ru releases from the REDOX plant (Till et al. 2002). 

100

101

102

103

104

105

GM

95th %-ile

Year

1952 1953 1954 1955

0.27

0.027

2.7

27

270

Estimated

release (Ci)

Estimated monthly release (GBq)

Figure 4.2.1-6. Estimated releases of 106Ru from REDOX Plant. (Till et 

al. 2002).

Releases of Tritium from 108-B 

Between 1949 and 1954, the Hanford Site produced tritium for the early weapons development 

period; the tritium was extracted in the 108-B facility from targets irradiated in the Hanford reactors. 

The product tritium was collected in flasks and sent to Los Alamos in gaseous diatomic form (T2). The 

facility initially had a roof vent about 75 feet off the ground, and eventually all building and hood air 

was exhausted to a 300-foot stack. Releases from both routine operations and process upsets were 
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 16 of 33

estimated by Heeb and Gydesen (1994). Heeb and Gydesen described the uncertainty in the 

releases using a uniform distribution ranging from 0.222 to 1.778 times the central estimate. For the 

purposes of propagating the uncertainty in this dose reconstruction, that has been approximated as a 

standard deviation of 40% of the central estimate. Total annual releases and standard deviations are 

presented in Table 4.2.1-3.

Table 4.2.1-3. Annual amount of tritium 

released from 108-B 

Year Tritium 

Released (Ci)

Standard 

Deviation (Ci)

1949 683 273

1950 6134 2455

1951 27060 10824

1952 39737 15895

1953 3911 1564

1954 122728 49091

The releases were primarily elemental tritium. Elemental tritium slowly oxidizes to tritiated water 

(HTO and T2O) in the atmosphere. If dose reconstruction inhalation estimates are made with dose 

conversion factors for tritiated water, the level of conservatism will range from factors between 1 and 

1000.

4.2.2

Beginning in 1946 beta activity was monitored on air filters to measure 131I concentrations in air (HW9871) and in 1951 alpha monitoring began (HW-44215). The reported values are of limited utility 

because the atmospheric releases from weapons testing in the 1950s contributed to activity on the 

environmental filters that was not associated with operations at the Hanford site. However the 

measured activities are useful as a check on the atmospheric dispersion calculations used to 

calculate occupational environmental doses. 

Environmental Air Monitoring

4.2.3

The computer program RATCHET and an Excel® spreadsheet were used to calculated claimantfavorable but realistic intakes from airborne radionuclides as opposed to the computer program Hcalc 

(Till et al. 2002) because Hcalc calculates “worst case” or maximum hypothetical dose as opposed to 

a realistic dose. Examples of the conservative overbiasing in the Hcalc program include:

Intake of Airborne Radionuclides 

• The program neglects plume rise at the point of release of radionuclides to the atmosphere. 

Without plume rise the program overestimates air concentrations and deposition on vegetation 

and soil near the point of release.

• The program neglects plume depletion caused by wet and dry deposition. Without plume 

depletion this program overestimates air concentrations and deposition on vegetation and soil.

• The program overestimates the radionuclides concentrations in the shallow surface soil and 

the external gamma dose because the program neglects leaching. 

• The program assumes a 12-year, as opposed to the NCRP (1996) default value of 30-year, 

buildup of radionuclides in the root zone of soil. The smaller buildup maximizes root uptake for 
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 17 of 33

• the food ingestion pathway. The work scope of the Hanford Technical Basis Document 

specifically excludes the food pathway. 

The computer file scrlist.dat (Till et al. 2002) provided the initial source terms in the spreadsheet. That 

file was based on the extensive research performed by Heeb (1994). The files from Till et al. (2002) 

provide monthly release estimates for the period from Hanford Site startup in 1944 through 1961. 

These files were extended to Hanford facility shutdown dates using the data from Heeb (1994), 

augmented with the revisions to the 131I releases by Napier (2002). Minor releases in the 1980s were 

also added as reported in the Hanford Site annual reports for those years. The 41Ar source terms for 

the reactors from Till et al. (2002) were also extended through the date when each reactor was shut 

down using the approach used in that report. The 239Pu releases from the Z Plant were also extended 

using the two-month-lag-time approximation of Till et all (2002). Because of differences in estimating 

atmospheric transport described below, emissions were tabulated as particulate, iodine, and noble 

gases. The following radionuclides were evaluated:

• 41Ar

• 144Ce144Pr

• 137Cs137Ba

• 3

H 

• 131I-131mXe

• 239Pu

• 103Ru103mRh

• 106Ru106Rh

• 90Sr90Y 

• 95Zr95Nb

Annual emissions were evaluated for the following sources:

• T Plant particles

• B Plant particles

• REDOX particles

• PUREX particles

• Z Plant particles

• T Plant iodine

• B Plant iodine

• REDOX iodine

• PUREX iodine

• B & C reactor noble gas

• KE & KW reactors noble gas

• N reactor noble gas

• D & DR reactors noble gas

• H reactor noble gas 

• F reactor noble gas

• 108-B elemental Tritium

Uncertainties in the source term were described using the “uncertainty factor estimates” of Heeb 

(1994). The list of source terms is presented in Attachments A-1 through A-9 along with the 

uncertainties expressed as a standard deviation. Some uncertainties in the decade of the 1980s were 

approximated as the standard deviation equal to 10 % of the measured values. Uncertainties are 
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 18 of 33

presented as standard deviations in Table A-10, atmospheric dispersion factors. The estimated 

intakes are assumed to be lognormally distributed and are presented in GSD which can be expressed 

as (Till, et al. 2003)

 ( 1 

GSD = (

) 

95th percentile

 50th percentile

) 1.65585

See also section 4.4 for additional information on uncertainties.

The computer program RATCHET (Ramsdell et al. 1994) was used to calculate annual average 

atmospheric dispersion coefficients. The RATCHET code was run for unit releases of 1 μm particles, 

noble gases, and iodine speciated as a combination of elemental iodine, particle-bound iodine, and 

organic iodine as described in Farris, et al. (1994). Hourly observations of wind speed, direction, 

stability, and precipitation from the extensive Hanford network of meteorological monitoring stations 

were used as input to the code. Results were calculated for monthly intervals from 1993 through 

2002. A dense calculation output grid of 41X53 nodes on 1-km centers was used for all release 

points. Output was integrated to give total integrated exposure, in units of Bq-sec/m3 per Bq released. 

These normalized values were then averaged over the 10-year observation period to provide monthly 

averages and standard deviations, which were then further rolled up into annual averages and 

standard deviations and are presented in Attachment A-10. The dose reconstructionist can calculate 

intakes for different source terms than those presented in Attachments A-1 through A-9 by multiplying 

the atmospheric dispersion coefficient in Attachment A-10 by the source term in Bq.

A total of 38 potential receptor locations were selected to represent exposure locations on the Hanford 

Site. These locations are listed in Table 4.2.3-1, along with the east-west and north-south node 

identifiers from the computational grid and the longitude and latitude of each point. The locations are 

illustrated in Figure 4.1-1.

The atmospheric dispersion factors for each location were multiplied by the emission rates from each 

source by radionuclide for each year from 1944 through 2001 even though the emissions from the 

reactors or the chemical separations plants after 1988 were minimal. The resulting annual air 

concentrations were then multiplied by 2400 m3 per year which is the recommended breathing rate by 

reference man doing light work of 1.2 m3

/hour times a use factor of 2,000 hours per year (SR-TBD 

2003). A standard deviation of 0.4 m3

/hour was assigned to this breathing rate. The final intake 

results presented in Attachments A-13 through A-21 provide the annual intake in Bq/yr for each 

receptor location by year by radionuclide. Maximum intake values by radionuclide are presented 

below.
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 19 of 33

Radionuclide Maximum Intake in Bq

144Ce 6.64E1

137Cs 2.35E0

3

H 1.15E5

131I 1.04E5

239Pu 1.47E-2

103Ru 1.93E2

106Ru 5.84E2

90Sr 2.67E0

95Zr 7.92E1

In a similar fashion, the annual exposures for air submersion in 41Ar were adjusted for 2000 hour/year 

occupancy. Those exposure values in Bq-sec/m3 were multiplied by the dose factor 6.15 x 10-14 Sv 

per Bq-sec/m3 (FGR 13) to give a submersion dose in sieverts that are presented in Attachment A-11. 

(1 Sv = 100 rem). Similarly the annual exposures from 41Ar were multiplied by the dose factor 1.01 x 

10-13 Sv per Bq-sec/m3 (FGR 13)to give the skin beta-gamma dose in sieverts in Attachment A-12. . 

The maximum 41Ar submersion dose was 3.47 x 10-5 Sv and the maximum 41Ar beta skin dose was 

5.7 x 10-5. 

The dose reconstructionist would then be able to select the years of exposure of a worker and the 

radionuclides related to the worker’s cancer and determine the occupational environmental exposure.

As an example:

Worker exposed at the Wye Barricade guard shack from 1947-1949.

Worker developed thyroid cancer. Using Attachment A-17 the intake was:

Date

1947

131I Bq

1.89 × 103

1948 1.08 × 102

1949 4.69 × 102

Total 2.47 x 103

The reconstructionist can calculate the dose from an intake of 2,470 Bq and enter the dose into the 

computer program NIOSH_IREP to calculate the probability of causation of the cancer. 
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 20 of 33

Table 4.2.3-1. Selected receptor locations 

with identifying computational nodes. 

Receptor location E-W Node N-S Node

T Plant 12 30

B Plant 20 29

REDOX 11 28

PUREX 20 29

Z Plant 11 29

B & C Reactors 9 37

KW & KE Reactors 13 39

N Reactor 16 43

D & DR Reactors 18 45

H Reactor 22 46

F Reactor 25 41

200 N 12 34

Midway (Riverland) 3 38

West Waluke 11 46

North Waluke 21 49

East Waluke 27 46

Yakima Barricade 4 32

Prosser Barricade 28 11

Wye Barricade 29 21

200 Firestation 15 29

100 Firestation 17 38

HMS Tower (622) 14 30

Columbia Camp 26 10

North Richland 38 6

300 Area 38 9

1100 Area 37 3

EOC/ALE Hq 19 10

Hanford Townsite 31 32

Waste Disposal Site 26 21

WNP2 Region 34 21

FFTF Region 31 14

Army H-61 8 32

Army H-51 8 26

Army H-42 18 22

Army H-40 20 28

Army H-50 8 28

200E Guard House 19 28

200W Guard House 12 30

4.3 EXTERNAL DOSE

4.3.1

The chemical separations plants began operations in April, 1945. Quarterly environmental monitoring 

reports published from 1945 to 1955 and annual environmental reports published since 1956 present 

gamma exposure levels at various locations throughout the Hanford site. Up through 1953 radiation 

exposure measurements were reported in milliroentgen (mR), milliroentgen-equivalent-physical 

(mrep), and subsequently in millirad (mrad). Hanf and Thiede (1994) stated that the difference in 

deposited energy in tissue between units is so small that the units can be considered nearly identical. 

Ambient Radiation
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 21 of 33

The data in HW-9871 summarized measured natural background radiation levels between 1946 and 

1948 as 0.3 to 0.5 mrad per day. For the purpose of the Hanford Technical Basis Document the 

natural gamma background radiation level attributed to cosmic radiation and naturally occurring 

radioactive materials in the environment is assumed to be 0.4 mrad per day or 146 mrad/yr. The work 

scope from NIOSH for the Hanford Technical Basis Document precludes subtraction of background 

from ambient readings.

Figure 4.3.1-1 illustrates that external gamma radiation attributed to site operations in the chemical 

separations area (200-East) averages 0.4 mrad/day above background levels and reached maximum 

exposures in 1945 and 1946. The external gamma exposure levels measured near the reactors were 

near natural background levels (HW-9871). Figure 4.3.1-2 illustrates the exposure rates measured 

near the REDOX Plant and the closest residence location to REDOX which were military sites H-50, 

H-51, and H-61 (HW-34882).

The relationship between 131I and 106Ru releases per year, and the net radiation exposures levels 

measured between at the REDOX plant perimeter and between the 200 areas is illustrated in Figure 

4.3.1-3. The net gamma exposure rates are mainly due to the 131I and 106Ru release. The principal 

gamma ray from 131I is 0.364 MeV emitted 82% of the time. The principal gamma rays from106Ru are 

from its progeny 106Rh and are 0.512 MeV emitted 21% of the time and 0.622 MeV emitted 11% of the 

time.

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

10/10/4510/31/4511/21/4512/12/45

1/2/462/6/46

3/13/46

4/3/46

4/24/465/15/46

6/5/46

6/26/467/17/46

8/7/46

8/31/46

10/15/4611/30/46

1/15/472/28/474/15/475/31/478/31/47

11/30/47

2/28/485/31/488/31/48

11/30/48

End of sampling interval

mrep per 24 hours

200-E

100-B

Figure 4.3.1-1. Radiation levels measured by detachable C chambers at two 

locations on the Hanford Site, 1945–1948. Levels at 200-East (separations area) 

averaged roughly twice those at 100-B (a reactor area). The average level at 

100-B was 0.35 mrep per 24 hours, which is within the stated background range 

of the instrument (0.3–0.5 mrep per 24 hours), and the average level at 200-East 

was 0.75 mrep per 24 hours (data from HW-9871) (Till et al. 2002).
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 22 of 33

0.1

1

10

100

Aug-50

Oct-50

Dec-50

Feb-51

Apr-51

Jun-51

Aug-51

Oct-51

Dec-51

Feb-52

Apr-52

Jun-52

Aug-52

Oct-52

Dec-52

Feb-53

Apr-53

Jun-53

Aug-53

Oct-53

Dec-53

Feb-54

Apr-54

Jun-54

Aug-54

Oct-54

Dec-54

Feb-55

Apr-55

Jun-55

Aug-55

Oct-55

Dec-55

Month and year

mrep or mrad per day

Redox perimeter

Redox area

PSN 300 (aka H-61)

PSN 310 (aka H-51)

PSN 320 (aka H 50)

PSN330 (aka H-40)

Note logarithmic scale

Figure 4.3.1-2. Exposure rates measured near the REDOX Plant and at 

four military installations. Measured exposure rates at the REDOX 

perimeter are the highest of all environmental stations monitored between 

1945 and 1955. Monitoring at the perimeter was discontinued in December 

1954, although monitoring continued in the REDOX area (Till et al. 2002)

0

100

200

300

400

500

600

1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955

Year

kCi I-131 or Ci Ru-106 released

0

5

10

15

20

25

Net expposure rate (mrep or mrad per day)

kCi I-131 released (mean estimate)

Ci Ru-106 released (mean estimate)

Net exposure rate at REDOX perimeter

(Gross-0.4)

Net exposure rate between 200 Areas

(Gross Annual Ave. - 0.4)

Figure 4.3.1-3. Time trends in annual 131I and 106Ru releases to air and 

net exposure rates between the 200 Areas (Building 622) and at the 

REDOX plant perimeter. A measured background exposure rate of 0.4 

mrep per day was subtracted from the onsite exposure rate measurements 

to obtain net exposure rate (Till et al. 2002).
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 23 of 33

Table 4.3.1-1 presents the external gamma measurements at Hanford from 1944 through 2001 

including fallout and background. The values are average values in mrem per year for exposures of 

2000 hours per year. Blank values in the table indicate that measurements were not available for 

those years. 

Table 4.3.1-1. External gamma radiation at Hanford (mrem/yr). 

300 Area 

400 

Area/ 

FFTF 

Hanford 

Townsite

Columbia 

Camp

Prosser 

Barricade ALE Wahluke 

WNP2 

Region 

Wye 

Barricade

Yakima 

Barricade

Army 

Loop

1945 170 149

1946 69 41

1947 121 88

1948 76 115

1949 60 158

1950 49 32

1951 49 32

1952 96 15

1953 35 23

1954 24 31

1955 84 76

1956 160 126

1957 269

1958

1959

1960 1,3 80 30 30 30 30 30 30 30 30 30 30

1961 1,3 80 30 30 30 30 30 30 30 30 30 30

1962 1,3 80 39 39 39 39 39 39 39 39 39 39

1963 1,4 46 39 39 39 39 39 39 39 39 39 39

1964 1,4 46 34 34 34 34 34 34 34 34 34 34

1965 1,5 46 27 27 27 27 27 27 27 27 27 27

1966 39 30 44 30 30 30 30 30 30 30 30

1967 40 49

1968 39 35

1969 80

1970 31 13

1971 17 16 13 15 16 13 16

1972 21 19 17 18 20 16 22

1973 18 16 16 17 17 17 16 17

1974 17 16 15 17 17 17 16 18

1975 17 16 15 16 17 17 16 17

1976 16 16 15 16 17 16 16 17

1977 16 16 15 16 16 17 15 17

1978 15 16 15 16 16 16 16 17

1979 16 16 16 17 18 18 17 18

1980 19 16 16 17 17 17 16 18

1981 29 16 16 18 18 17 17 18

1982 121 16 17 17 18 18 17 18

1983 98 17 16 16 16 18 18 17 18 17

1984 21 17 16 15 16 17 18 17 18 16

1985 19 14 13 14 15 16 16 16 15 16 15

1986 21 16 12 16 17 17 16 15 14 17 16

1987 21 18 17 18 19 20 19 18 18 21 19

1988 19 19 18 20 20 21 20 19 18 21 20

1989 20 20 19 19 20 21 20 23 18 23 21

1990 19 19 19 18 17 20 20 20 19 20 19

1991 22 21 21 21

1992 22 22 22 21
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 24 of 33

1993 21 23 20 22

1994 24 24 24 24

1995 19 19 20 19

1996 18 19 20

1997 18 19 19

1998 19 19 20 21 19 19 21 19

1999 19 19 20 20 22 21 21 20 22 20

2000 19 19 17 20 20 20 20 19 22 19

2001 19 19 18 21 22 21 20 20 22 20 1 Based on the annual average dose rate for entire Hanford Site as reported in annual reports, except for 100, 200, and 300 areas.

Table 4.3.1-1. External gamma radiation at Hanford (mrem/yr) (cont’d)

100 

Area 

Fire 

Station 100 B 100 D 100 F 100 K 100 N 100 H

1100 

Area 

200 

East 

200 

West 200 N

1945 127 135 123 194 185

1946 47 33 38 122 50

1947 42 60 85 115 57

1948 24 52 76 67 30

1949 31 17 38 25 16 20

1950 55 44 40 37 37 45

1951 55 44 40 37 37 45

1952 35 31 19 33 13 37

1953 48 33 34 38 49 63

1954 88 119 71 133 71 217

1955 38 95 253 87 35 178 265

1956 347 216 258 37 242 230

19572 146 

19582 319 

19592 173 

19603 111 99 127 87 55 98 143

19613 111 99 127 87 55 98 143

19623 111 99 127 87 55 98 143

19634 30 53 45 52 118 76 46 30 64 45 30

19644 30 53 45 52 118 76 46 30 64 45 30

19654 30 53 45 52 118 76 46 64 45 30

1966 30 53 48 44 108 56 39 30 66 56 30

1967 60 47 75 125 69 53 69 41

1968 63 47 49 157 95 46 42 41

1969 62 55 69 125 83 103 57

1970 29 29 24 74 39 31

1971 17 16 17 31 30 17

1972 17 19 24 34 30 21

1973 16 18 18 17 37 37 21

1974 16 17 18 17 22 33 22

1975 18 17 17 17 22 31 21

1976 16 17 15 15 19 27 18

1977 15 16 15 14 20 27 19

1978 16 17 15 21 15 22 20

1979 16 18 16 21 14 22 21

1980 16 17 15 20 14 22 18

1981 17 17 15 20 14 21 18

1982 16 17 17 21 14 21 17

1983 17 17 15 21 15 17 18

1984 16 18 17 21 15 17

1985 13 15 13 18 14 14 16
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 25 of 33

1986 15 16 13 20 14 16 16

1987 18 19 17 20 17 19 19

1988 18 20 17 21 18 19 20

1989 19 19 18 21 20 20 20 20

1990 19 19 18 21 17 17 20 19

1991 27 19 23 19 20 21 21

1992 21 20 24 20 22 22 23

1993 23 19 23 19 22 23 23

1994 25 22 28 22 24 25 26

1995 20 16 17 19 19 20

1996 20 16 17 19 19 20

1997 20 16 16 19 18 20

1998 20 17 17 19 19 21

1999 20 20 16 17 20 20 22

2000 19 19 17 17 19 19 21

2001 20 20 18 19 20 19 21 2 Based on Monthly reports where dose rate ranges (max and min) were reported for “Separations Area” and “Residential 

Area” only. Maximum dose rate reported here.

3 Based on an average of 1952-1956 gamma levels at the 100, 200, and 300 areas. 4 Based on an average of 1966-1970 gamma levels at the 100, 200, and 300 areas. 

4.3.2

Xenon

Releases of Noble Gases

The relative dose contribution of 133Xe to 131I can be estimated by comparing the products of the 

release rates and the dose conversion factors. At its peak in 1946 the 133Xe release rate was 42,000 

Ci per month. The increase in fuel element cooling time that began in 1946 resulted in more than a 

10-fold reduction in 133Xe releases to the atmosphere and continued in subsequent years. The 131I 

release rate at the peak Xe release rate was 89,000 Ci per month. The dose conversion factor for 

133Xe is 4.3 x 10-8 and for 131I is 2.4 x 10-4 Sv per Bqm-3. Comparing the products of the release rate 

and the dose conversion factor for each radionuclide, the 131I contribution to the dose was more than 

10,000 times larger than that from 133Xe (Till et al. 2002). Thus 131I is listed as a major contributor to 

the occupational environmental dose and 133Xe is not. 

Argon releases from the Production Reactors

41Ar was released from the Hanford reactors as a neutron activation product of stable argon in air and 

not from the chemical separations facilities. Effluent concentrations were measured for only brief 

periods over the years and the reactors did not operate all the time. Despite those problems Till et al. 

(2002) created percentiles from the distributions of monthly releases of 41Ar which are presented in 

Table 4.3.2-1. The 41Ar concentrations in the reactor stacks and the stack flow rates are presented in 

Table 4.3.2-2.
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 26 of 33

Table 4.3.2-1. Distributions of monthly release estimates for 41Ar from reactors 

and areas. (Till et al., 2002).

Reactor

Percentiles of distributions of release estimates

(Ci mo–1) for individual reactors and areas with two reactors

5th 25th 50th 75th 95th

B, D, or F 320 1200 2200 3300 4100

C 4000 5600 7000 8700 11000

B and Ca 5600 7600 9300 11000 14000

DR 5900 6600 7600 8500 9400

D and DRb 7100 8600 9800 11000 13000

H 5700 7000 8600 10000 12000

KE 4200 5900 7400 9100 12000

KW 4100 5600 7000 8700 11000

KE and KWc 10000 13000 15000 17000 20000

a. Both reactors operated in the same area after November 1952.

b. Both reactors operated in the same area after October 1950.

c. Both reactors operated in the same area after April 1955.

Table 4.3.2-2. Argon-41 concentrations measured in and effluent flow rates for 

production reactor stacks. (Till et al. 2002)

Reactor Nb

Measured concentration (μCi m–3) of 41Ara Stack effluent

flow rate (m3 s–1)

c Average Maximum

B 0 20 39 47

D 4 23 39 47

F 0 17 27 47

DR 11 80 110 40

C 3 <4 <4 64

H 8 48 66 76

KE d d d 67

KW d d d 64

a. 41Ar concentration data from Paas (1953a). 

b. Number of samples collected (Paas 1953a,b,). 

c. Based on flow rates given in Heeb (1994). 

d. The reactor was not operating at the time of the measurements.

4.3.3

Particulate emissions occurred from 1945 through 1955 from T and B plants and from 1952 through 

1955 from the REDOX plant. Notable were the large ammonium sulfate flakes containing 103Ru and 

106Ru that were emitted in March 1952. The median estimate for the total release activity was 145 Ci 

(5.37 TBq). An estimated 290 million particles were released. Based on binomial and Poisson 

distribution theory the probability that an individual would encounter one or more released particles on 

their skin is almost one (Till et al. 2002)

Skin Deposition of Airborne Particulate Emissions 

Till et al. (2002) calculated the number of radioactive particles from the REDOX Plant that would fall 

on a person at different locations during the 1950s. The values ranged from 100 particles for a 

person in Richland to 830 particles at military location H-50. Since the numbers are maximum values 

for 24-hour occupancy 7 days a week, the numbers should be multiplied by the use factor of 0.1 to 

provide a realistic, claimant favorable number of particles. The use factor was developed as follows.

If one assumes that an individual works 8 work hours per day, 5 days a week the use factor would be 

40 work hours divided by 168 hours per week or 0.24. If the workers hands, forearms, and head are 
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 27 of 33

uncovered 0.16 of his surface area is available for deposition on the skin as opposed to deposition on 

a worker’s clothing. If the worker wears shorts and a short-sleeved shirt 0.33 of his skin is available 

for deposition (Till et al. 2002). Multiplying the work hour factor by the exposed skin factor gives a

range of use factors of 0.04 to 0.08. Thus a use factor of 0.1 is a claimant favorable use factor. Using 

the 0.1 use factor the greatest number of particle encounters at any of the military camps is 83 

particles from March 1952 through June 1954 at military location H-50. Table 4.3.3-1 presents the 

number of particles that would be expected to fall on a person by location assuming a use factor of 

0.1.

Table 4.3.3-1. Expected Number of Particle Encounters for REDOX Plant Emissions 

during the Early 1950s assuming a use factor of 0.1. (original data from Till et al. 2002).

Location

Month/yr H-61 H-51 H-42 H-40 H-50

200-E 

Tower

200-W

Tower

Hanford

Townsite

Mar-52 1.1E+01 9.2E+00 2.3E+01 5.9E+00 2.6E+01 7.1E+00 2.1E+01 2.5E+00

Apr-52 7.5E-01 6.5E-01 1.6E+00 4.2E-01 1.9E+00 5.0E-01 1.5E+00 1.8E-01

Jun-52 6.7E-03 5.7E-03 1.5E-02 3.8E-03 1.6E-02 4.5E-03 1.3E-02 1.8E-03

Sep-53 3.9E-02 3.3E-02 8.5E-02 2.2E-02 9.2E-02 2.6E-02 7.3E-02 1.0E-02

Aug-53 5.3E-02 4.4E-02 1.1E-01 3.0E-02 1.2E-01 3.5E-02 9.8E-02 1.4E-02

Sep-53 7.4E+00 6.2E+00 1.6E+01 4.2E+00 1.7E+01 5.0E+00 1.4E+01 1.9E+00

Jan-54 1.5E+01 1.3E+01 3.2E+01 8.3E+00 3.7E+01 1.0E+01 3.0E+01 3.5E+00

Apr-54 1.1E-02 9.6E-03 2.5E-02 6.5E-03 2.7E-02 7.7E-03 2.1E-02 3.0E-03

May-54 2.7E-02 2.3E-02 6.0E-02 1.6E-02 6.6E-02 1.9E-02 5.2E-02 7.2E-03

Jun-54 4.3E-03 3.7E-03 9.5E-03 2.5E-03 1.0E-02 3.0E-03 8.3E-03 1.1E-03

Total 3.4E+01 2.9E+01 7.3E+01 1.9E+01 8.2E+01 2.3E+01 6.7E+01 8.1E+00

Table 4.3.3-2 presents the dose coefficients for different radionuclides attached to or contained in the 

particles released to the air. Based on 5 μCi (1.85 E5 Bq) particles released as iron particles in the 

1940 and a use factor of 0.1, the estimated skin dose rate was 1.2-3.6 rads per hour assuming a 

mean residence time on the skin of 1.4-4.3 hours (Whicker and Schultz 1982). Likewise for the 

ruthenium particles containing 300 μCi (1.11E7 Bq) 106Ru and 170 μCi (6.29E6 Bq). 103Ru released in 

the 1950s the estimated skin dose rate was 130-240 rads per hour.

Table 4.3.3-2. Dose coefficients for radionuclides contained in Hanford active particles. 

(Till et al. 2002).

Primary radionuclide 

and (decay product)

Fraction of beta activity 

for T and B Plant particles

Dose coefficient (nGy h–1 per Bq cm–2)

a

Skin depth of 0.07 mm Skin depth of 0.4 mm 103Ru 0.13 568 28 141Ce 0.14 1538 169 95Zr (95Nb) 0.06 1288 86 89Sr 0.14 1667 887 91Y 0.23 1669 897 106Ru (106Rh) 0.03 1845 1165 144Ce (144Pr) 0.26 2630 634 90Sr (90Y) 0.05 3133 1384 137Cs 0.05 1432 384

a. Dose coefficients for distances along the axis of a circular source with area of 1 cm2 or a point source 

averaged over that area from Cross et al. (1992). Tabled values include contributions of radioactive 

decay products. For short exposure times, doses attributed to 95Zr and 90Sr would be overestimated 

because the half-lives of 95Nb and 90Y are 35.1 d and 64.1 h, respectively.
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 28 of 33

4.4 UNCERTAINTIES

The calculation of the occupational radiation dose to an individual is specific to the past activities of 

the individual. The dose reconstructionist needs to know the dates that the individual was present at 

Hanford, where he worked, the type of work performed, the amount of time he spent outside facilities 

such as process buildings, chemical separations plants, product handling plants, reactors or other 

structures where his radiation exposure was monitored. The NIOSH work scope for the Hanford 

Technical Basis Document specifically excluded the radiation dose from foods, including milk, and 

resuspension as not a result of occupational exposures at Hanford. 

Occupational environmental doses at Hanford include but are not limited to:

• Internal Dose from Airborne Concentrations

• External Doses from Plumes

• External Doses from Skin Deposition

The total occupational environmental dose is the sum of the environmental doses applicable to an 

individual submitting a claim under the Energy Employees Occupational Illness Compensation 

Program Act of 2000. The work of others has provided estimates of the upper and lower bounds of 

the occupational environmental dose at Hanford. 

The lower bound is provided by Farris et al. 1994. They calculated the off-site environmental doses. 

The lowest environmental dose at the boundary of the Hanford Site is presented below and is the 

lower bound on the occupational environmental dose received on site:

Cumulative 131I dose to the thyroid of an adult from all air exposure 1944-1951 with milk cows 

on fresh pasture is 1-3 rad. Since the work scope for the Hanford TBD specifically excludes 

food pathways and the external and inhalation doses account for 36% of the total dose, the 

lower bound without doses from the food pathway would be (1-3 rad)(0.36) = 0.36-1.07 rad 

over 7 years or 0.051–0.154 rad/yr. 

Cumulative effective dose to an adult at Richland, 1945-1972 is 0.42 rem or 0.016 rem/yr

The upper bound is provided by Till et al. 2002. They calculated the “worst case” on-site 

environmental dose as follows:

. 

For a hypothetical person on site 24 hours a day from1945 through 1961 without any ingestion 

pathways the absorbed dose to the thyroid was estimated to be 120 rad and an cumulative 

effective whole-body dose to be 6.5 rem. NOTE: That calculation is of marginal value since no 

one could have lived 24 hours a day for 17 years on site.

For a worker that spent 2000 hours a year from 1945 through 1961 on the Hanford site the 

absorbed dose to the thyroid was estimated at 27 rem or 1.688 rem/yr. His cumulative 

effective whole-body dose from the inhalation of airborne particulates and from gaseous 

releases was an estimated 2.6 rem or 0.08 rem/yr

Note: The upper and lower bounds were derived from exposures that began in the mid 1940s and 

lasted 7-27 years. Since exposures were greatest in the early years, the dose reconstructionist 

should apply the derived upper and lower bounds only to similar time periods.

. 
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 29 of 33

Uncertainties in the estimation of the occupational environmental dose to individuals present on the 

Hanford Site begin with the determination of when the person was on site, where he worked on site, 

what type of work was done outside the facilities such as process buildings, the chemical separations 

plant, the material handling buildings, the reactors, or other facilities. Additional uncertainties are the 

determination of the quantity, concentration, date, and duration of effluents from records that were 

often incomplete especially in the early days at Hanford. Uncertainties were present in the air 

dispersion modeling of radionuclides at receptor locations such as uncertainties in the meteorological 

data used in the modeling. Other uncertainties associated with the fate of the dispersed particles and 

gases include estimates of the breathing rates of the workers, the amount of skin covered by work 

clothes, and the retention time of the deposited particulates on the skin. 

The range of uncertainties for the final dose estimates produced by the dose reconstructionist for work 

that began in 1945 and extended until approximately 1972 may be calculated by multiplying the dose 

rates presented above by the years worked, viz. 

The range of doses to the thyroid of an adult is 1 - 45 rem.

The intakes calculated and presented in Attachments A-13 through A-21 can be used by the dose 

reconstructionist to calculate doses. The following example indicates that those doses should 

approximate the ranges presented above:

The range of cumulative effective whole-body dose due to environmental occupational 

exposures to an adult worker is 0.44 - 2.5 rem.

The maximum intake presented in Attachment A-17 for 131I is 1.04 x 105 Bq/yr. Using a dose 

factor of 7.39 x 10-7 rem/Bq for a 27 year exposure, the cumulative effective whole-body dose 

is (1.04 x 105 Bq/yr)(7.39 x 10-7)(27) = 2.1 rem. That value falls in the range of 0.44 – 2.5 rem 

presented above. 

Considering that one is attempting to reconstruct events that occurred a half century ago the 

uncertainties are large compared to today’s events where record keeping and dosimetry systems are 

much more precise. With large uncertainties the use of realistic data favorable to the claimant is 

justified. The creation and use of worst-case scenarios, such as working 24 hours on site for 17 

years, only increases the uncertainty of the final estimated dose. 
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 30 of 33

REFERENCES

Ballinger, M. Y., and R. B. Hall. 1991. A History of Major Hanford Facilities and Processes Involving 

Radioactive Material. PNL-6964, Pacific Northwest Laboratories, Richland, Washington.

Cross, W. G., N. O. Freedman, and P. Y. Young. 1992. “Beta Ray Dose Distributions from Skin 

Contamination.” Rad. Prot. Dos. 40:149-168.

Crystal Ball. 2001. User Manual. Decisioneering, Inc., Denver, Colorado. p. 341

Farris, W. T., B. A. Napier, P.W. Eslinger, T. A. Ikenberry, D. B. Shipler, J. C. Simpson. 1994. 

Atmospheric Pathway Dosimetry report, 1944-1992. PNWD-2228 HEDR UC-000.

FGR 13. Federal Guidance Report No. 13, Cancer Risk Coefficients for Environmental Exposure to 

Radionuclides, EPA 402-R-99-001, Office of Radiation and Indoor Air, United States 

Environmental Protection Agency, Washington, DC 200460, September 1999.

Foster, R. F., and I. C. Nelson. 1061. Evaluation of Radiological Conditions in the Vicinity of Hanford 

for 1960. HW-68435. June 1.

Gerber, M. S., 1992. Legend and Legacy: Fifty Years of Defense Production at the Hanford Site.

WHC-MR-0293, Revision 2, Hanford Reading Room Number 10879, September.

Gerber, M. S. 1993. “Manhattan Project Buildings and Facilities at the Hanford Site: A Construction 

History.” WCH-MR-0425 UC 630. Flour MSIN B-3-30. P. O. Box 1000 Richland, WA 99352, 

September.

Groves, L. R. 1962. Now It Can Be Told. Harper and Brothers, New York

Gydesen, S.P. 1992, Documents Containing Operating Data for Hanford Separations Processes, 

1944-1972, PNWD-2028-HEDR. Hanford Reading Room Number 11858, September.

Hanf, R. W., and M. E. Thiede. 1994. Environmental Radiological Monitoring of Air, Rain, and Snow 

on and near the Hanford Site, 1945-1957. PNWD-2234 HEDR. Hanford Reading Room 

Number 13783, March.

Healy, J. W. 1977 An Explanation of the Pathways from Soil to Man for Plutonium. LA-6741-MS. Los 

Alamos Scientific Laboratory, Los Alamos, New Mexico. April.

Heeb, C. M. 1994. Radionuclide Releases to the Atmosphere from Hanford Operations, 1944-1972. 

PNWD-2222 HEDRl Hanford Reading Room Number 13197. May.

Heeb, C. M., and S. P. Gydesen. 1994. Sources of Secondary Radionuclide Releases from Hanford 

Operations, PNWD-2254 HEDR, Battelle Pacific Northwest Laboratories, Richland, 

Washington. 

HW 7865. 1947. Preliminary Report on Existing Active Particle Hazard – 200 Areas, Mickelson, M. L., 

Accession number 3944

HW 7920. 1947.Actions Taken on the Spot Contamination in the Separations Plant Areas, Parker, H. 

M., Hanford Technical Library (WSU)
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 31 of 33

HW 8624. 1948. Progress Report on “Action Taken on the Spot Contamination in the Separations 

Plant Area” (Follow up to HW 7920), Hanford Technical Library (WSU)

HW 9175. 1948. Stack Gas Decontamination, Separations Plants Development of Decontamination 

Systems, Hanford Technical Library (WSU)

HW 9871. 1948. Radioactive Contamination in the Columbia River and in the Air and Radiation Levels 

Measured in the Air at Hanford Works and Vicinity for 1945, Singlevich, W., Hanford Technical 

Library (WSU)

HW 10261. 1948.Radio-active Particle Investigation, Thorburn, R.C., Accession Number 8341

HW28780. 1953. Particles Emitted by 291-S Stack, Adley, F.E, W.E.Gill, H.B. Perry, R.H. Scott, D.E. 

Wisehart, Accession Number 4990

HW33061. 1954. Additional Pressure Drop Flow Characteristics of K Pile Outlet Tube Fitting 

Assembly, Greenfield, H. H, Accession Number D198147911 

HW 33068. 1954. Status of Ground Contamination Problems, Parker, H.M., Accession Number 1128

HW 34882. 1955. Technical Appraisal of REDOX Ruthenium Problems and their Resolution, Irish, E. 

R, Accession Number 8429

HW 42215. 1956. Radioactive Contamination in the Hanford Environs for the Period April, May, June 

1956, Anderson, B.V. and J.K. Soldat, Accession Number 1141

Johnson, W. E. 1954. “Undue Contamination in Construction Areas.” Letter from General Manger, 

General Electric to D. F. Shaw, Manager, AEC Handord Operation Office, June 8.

Junkins, R. R., E. C. Watson, I. C. Nelson, and R. C. Henle. 1960. Evaluations of Radiological 

Conditions in the Vicinity of Hanford for 1959. HW-64371. May 9.

NCRP. 1996. Screening Models for Releases of Radionuclides to Atmosphere, Surface Water, and 

Ground. NCRP Report No 123 I. Bethesda, Maryland, January 22.

Napier, B. A. 2002. “A Re-evaluation of the 131I Atmospheric Releases from the Hanford Site.” Health 

Physics 83:204-226

Parker, H. H. 1956. “Radiation Exposure from Environmental Hazards.” Proceedings of the 

International Conference on the Peaceful Uses of Atomic Energy, Geneva, Switzerland, 8 

August-20 August, 1955,Volume 13 Legal, Administrative, Health and Safety Aspects of 

Large-Scale Use of Nuclear Energy. United Nations, New York. p305-310.

Paas, H. J. 1953a. “Radioactive Contamination in the Hanford Environs for the Period January, 

February, March 1953. HW-28009. Hanford Reading Room 1121, May 21.

Paas, H. J. 1953b. “Radioactive Contamination in the Hanford Environs fro the Period October, 

November, December 1952. HW-27641. Hanford Reading Room 1120, April 20.
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 32 of 33

Poston, T. M., S. W. Hanf, R. L. Dirkes. 2000. Hanford Site Environmental Report for Calendar Year 

1999, PNNL-13230. Pacific Northwest National Laboratory, Richland, Washington

Ramsdell, J. V., Jr., C. A. Simonen, and K. W. Burk. 1994. Regional Atmospheric Transport Code for 

Hanford Emissions Tracking (RATCHET), PNWD-2224 HEDR, Battelle Pacific Northwest 

Laboratories, Richland, Washington

Schendiman, L. C. 1958. “Probability of Human Contact and Inhalation of Particles.” Health 

Physics1:352-356. Hanford Reading Room Number 1164.

Sehmel, G. A. 1980. “Transuranic and Tracer Simulate Resuspension.” In Transuranic Elements in 

the Environment. Edited by W. C. Hanson. DOE/TIC-22800. Hanford Reading Room Number 

6200, pp. 236-287.

SR-TBD. 2003. Savannah River Site Technical Basis Document, ORAU Team Dose Reconstruction 

Project for NIOSH, Draft Report Number ORAU-TKBS-0003

Till., J. E., P.G. Voilleque, G. G. Killough, and S.K. Rope. 2002. Methods for Estimating Radiation 

Doses from Short-Lived Gaseous Radionuclides and Radioactive Particles Released to the 

Atmosphere During Early Hanford Operations. RAC Report No. 2-CDC-Task Order 3-2000 –

Final.

Warren, J. H. 1961. Control of I-131 Releases to Atmosphere. HW-68392. Hanford Reading Room 

Number 7777. February 6.

Whicker, F. W., and V. Schultz. 1982. Radioecology: Nuclear Energy and the Environment, Volume 1. 

Boca Raton, Florida: CRC Press. Open Lit.
Effective Date: 10/15/2003 Revision No. 00 Document No. ORAUT-TKBS-0006-4 Page 33 of 33

GLOSSARY

None