DOE Review 12/17/2015 

Division of Compensation Analysis and Support 

Technical Basis Document for the Hooker Electrochemical 

Company 

Niagara Falls, New York 

Document Number: 

DCAS-TKBS-0009 

Effective Date: 12/08/2015 

Revision No.: 02 

Page 1 of 23

Subject Expert: David Allen

Approval: Signature on file 

James W. Neton, Associate Director for Science 

 

Date: 12/08/2015 

Supersedes: 

DCAS-TKBS-0009

Rev. 1 

TABLE OF CONTENTS 

Section Page 

1.0 Introduction .................................................................................................................................. 4

2.0 Site Description and Operational History ..................................................................................... 5

3.0 Process Description ...................................................................................................................... 6

3.1 Process at Hooker .......................................................................................................7

3.2 ElectroMet Slag Production ........................................................................................8

3.3 Mass Balance ............................................................................................................10

3.4 Work Flow ................................................................................................................11

4.0 Internal Dose ............................................................................................................................... 12

4.1 Operational Air Concentration ..................................................................................12

5.0 External Dose ............................................................................................................................. 16

5.1 Barrels .......................................................................................................................16

5.2 External Dose from Surface Contamination .............................................................17

5.3 External Dose Summary ...........................................................................................18

6.0 Residual Contamination ............................................................................................................. 18

7.0 Occupational Medical Dose ........................................................................................................ 20

8.0 References .................................................................................................................................. 21
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LIST OF TABLES

Table Page

Table 1: Mass Balances for Each Processing Interpretation....................................................................... 10

Table 2: Magnesium Fluoride Air Samples................................................................................................ 14

Table 3: Slag Barrel External Dose Rates................................................................................................... 17

Table 4: Concentrate External Dose Rates ................................................................................................. 17

Table 5: Surface Contamination External Dose Rates................................................................................ 17

Table 6: External Dose Summary ............................................................................................................... 18

Table 7: Residual Period Dose Summary ................................................................................................... 19

LIST OF FIGURES

Figure Page

Figure 1: Air Sample Distribution .............................................................................................................. 15
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RECORD OF ISSUE/REVISIONS

ISSUE

AUTHORIZATION

DATE

EFFECTIVE

DATE REV. NO. DESCRIPTION

4/4/2011 4/4/2011 0 Changes Battelle-TBD-6001 Appendix to 

a standalone document. Revises dose 

models to eliminate dependence on 

Battelle-TBD-6001. Provides more 

detailed description of dose models. 

Incorporate review comments.

06/16/2011 06/17/2011 1 Revision initiated to correct errors in 

Tables 2, 3, and 6. Renumber tables after 

Table 4. Added language on page 10 to 

indicate the 95th percentile of the airborne 

values was used. Corrected 

typographical error on page 7 and 14. 

11/10/2015 12/08/2015 2 Revision initiated to include information

about a Special Exposure Cohort 

designation for Hooker. Revision also 

incorporates changes due to new 

information describing the operations at 

Hooker.
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1.0 Introduction

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

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

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

preparation of dose reconstructions at particular Department of Energy (DOE) or Atomic 

Weapons Employer (AWE) facilities or categories of DOE or AWE facilities. They will be 

revised in the event additional relevant information is obtained about the affected DOE or AWE 

facility(ies). These documents may be used to assist NIOSH staff in the evaluation of Special 

Exposure Cohort (SEC) petitions and the completion of the individual work required for each 

dose reconstruction.

In this document the word “facility” is used to refer to an area, building, or group of buildings 

that served a specific purpose at a DOE or AWE facility. It does not mean, nor should it be 

equated to, an “AWE facility” or a “DOE facility.” The terms AWE and DOE facility are 

defined in sections 7348l(5) and (12) of the Energy Employees Occupational Illness 

Compensation Program Act of 2000 (EEOICPA), respectively. A DOE facility is defined as 

“any building, structure, or premise, including the grounds upon which such building, structure, 

or premise is located ... in which operations are, or have been, conducted by, or on behalf of, the 

[DOE] (except for buildings, structures, premises, grounds, or operations ... pertaining to the 

Naval Nuclear Propulsion Program),” and with regard to which the DOE has or had a proprietary 

interest; or “entered into a contract with an entity to provide management and operation, 

management and integration, environmental remediation services, construction, or maintenance 

services.” 42 U.S.C. § 7384l(12). On the other hand, an AWE facility means “a facility, owned 

by an atomic weapons employer, that is or was used to process or produce, for use by the United 

States, material that emitted radiation and was used in the production of an atomic weapon, 

excluding uranium mining or milling.” 42 U.S.C. § 7384l(5). The Department of Energy (DOE) 

determines whether a site meets the statutory definition of an AWE facility and the Department 

of Labor (DOL) determines if a site is a DOE facility and, if it is, designates it as such.

Accordingly, a Part B claim for benefits must be based on an energy employee’s eligible 

employment and occupational radiation exposure at a DOE or AWE facility during the facility’s 

designated time period and location (i.e., covered employment). After DOL determines that a 

claim meets the eligibility requirements under EEOICPA, DOL transmits the claim to NIOSH 

for a dose reconstruction. EEOICPA provides, among other things, guidance on eligible 

employment and types of radiation exposure to be included in an individual dose reconstruction. 

Under EEOICPA, eligible employment at an AWE facility is categorized as employment either 

(1) during “a period when the employer was processing or producing, for the use by the United 

States, material that emitted radiation and was used in the production of an atomic weapon, 

excluding uranium mining and milling,” (i.e., the operational period); or (2) during a period that 

NIOSH has determined that “there is a potential for significant residual contamination outside of 

the period in which weapons-related production occurred,” (i.e., the residual contamination 

period). 42 U.S.C. § 7384l(3).

Based on the abovementioned definition for eligible employment during an AWE facility’s 

operational period, NIOSH includes radiation exposures incurred in the performance of duty, 
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such as medical X-rays received as a condition of employment for participating in DOE projects, 

at an AWE facility in dose reconstructions. This may include radiation exposure related to the 

Naval Nuclear Propulsion Program and any radiation exposure received from the production of 

commercial radioactive products that were concurrently manufactured by the AWE facility 

during the operational period. In contrast, only two categories of radiation exposure as defined 

in 42 U.S.C. § 7384n(c)(4) should be included in dose reconstructions for claims involving 

employment during the residual contamination period. First, NIOSH must include exposures to 

radiological contaminants resulting from activities that had a nuclear-weapon nexus or conducted 

by or on behalf of the DOE (with an exclusion of activities related to, among other things, the 

Naval Nuclear Propulsion Program) that took place during the operational period. 42 U.S.C. § 

7384n(c)(4)(A). Second, radiation doses from sources not included in the first category but 

which cannot be distinguished through reliable documentation should also be included in dose 

reconstructions. 42 U.S.C. § 7384n(c)(4)(B). Furthermore, because all DOE-related activities 

have ceased during the residual contamination period, NIOSH does not include doses from 

medical X-rays performed during the residual contamination period (NIOSH 2007) in dose 

reconstructions.

Likewise, NIOSH does not consider the following types of exposure as those incurred in the 

performance of duty as a condition of employment for DOE-related activities at an AWE facility. 

Therefore these exposures are not included in dose reconstructions for either the operational or 

residual contamination period (NIOSH 2010):

 Background radiation, including radiation from naturally occurring radon present in 

conventional structures

 Radiation from X-rays received in the diagnosis of injuries or illnesses or for therapeutic 

reasons

The following information from the Department of Energy’s Office of Health, Safety and 

Security EEOICPA Find Facilities webpage defines the EEOICPA covered periods for the 

Hooker Electrochemical Company.

Site: Hooker Electrochemical Company

Location: Niagara Falls, New York

Covered Period: 1943-1948, Residual Radiation 1949-1976

This document contains a summary of the description of the site as well as the Atomic Energy 

Commission activities performed there, and provides the technical basis to be used to evaluate 

the occupational radiation doses for EEOICPA claims.

2.0 Site Description and Operational History

The Hooker Electrochemical Company (HEC) was located in Niagara Falls, New York. From 

January, 1943 until June, 1948 under contract No W-7405 eng-28 with the Manhattan Engineer 

District (MED), HEC manufactured various organic chemicals including xylene hexafluoride (P45), xylene hexachloride, and Miller’s Fluoro Lubricant (MFL). While these processes in 

themselves did not involve radioactive materials, during part of this period, hydrochloric acid, a 
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byproduct of the P-45 process, was used to chemically treat uranium bearing C-2 slag as a 

precursor to uranium recovery (DOE 1985, pg 58).

The HEC site used under the MED program was the “D” area, 5.5 acres located on the north 

bank of the Niagara River in Niagara Falls, NY, about 2 miles east of the falls. Five buildings on 

this site, D-5, 6, 7, 8 and 9 were used under the contract with MED (1943-48). The bulk of 

uranium handling was conducted outdoors in an area by the railroad siding north of these 

buildings. This activity involved the chemical processing of uranium-bearing slag for recovery 

purposes (DOE 1985, Olotka 1979).

The covered period for Hooker Electrochemical is listed by the Department of Energy’s Office 

of Worker Advocacy as 1943 through 1948 and includes both radioactive material processing 

and nonradioactive chemical production activities for the MED (DOE 2009). The only weaponsrelated radiation exposure occurred while processing uranium contaminated slag for MED. A 

49’ x 28’ x 25’ cinder block building to contain some of the necessary equipment was 

constructed under a letter of intent dated May 1944. Construction was completed and the 

building turned over to the Operating Department on July 11, 1944 (Dowling 1944). No 

documentation was found indicating there were other sources of radiation, commercial or 

weapons-related, at Hooker Electrochemical. 

An MED medical clearance document indicated the P-45 contract (which including the slag 

concentrating) had ended on 1/15/1946 (Mears 1946). Supplemental agreement number 7 to the

Hooker contract was dated 9/30/1945 and included a cost estimate to maintain the plant in 

standby from 11/1/1945 to 4/30/1946 (MED 1945). Another document indicated that the MED 

work at Hooker had shut down in October 1945 (Young 1985). This document also indicates the 

plant started back up in 1947 to make lubricants however, a monthly report from September 

1944 indicates that P-45 production was cutback 50% to permit the manufacture of the 

fluorinated lubricant MFL (Tybout 1944). Therefore, the restart is not an indication that the P-45 

(or slag concentrating process) restarted. Taken together, these documents indicate the slag 

concentrating work was placed in standby on 11/1/1945.

This document establishes the period of operational radiation exposure from July 11, 1944 to 

November 1, 1945. It is possible that the slag-processing occurred for an even shorter period 

since some start up period would be expected. This analysis assumes a period of residual 

radioactivity exposure from November 1, 1945 to October 11, 1976, the date when 

measurements for radiation and radioactivity onsite were made and it was concluded that no 

elevated levels of radioactivity were onsite (DOE 1977). 

3.0 Process Description

The MED radiation work at Hooker Electrochemical was the concentration of uranium from

slag, which had been sent to the Hooker site from the Electrometallurgical Company or 

Electromet (DOE 1985). This material was primarily reduction pot liners (dolomite) used in the 

reduction of UF4 to uranium metal.
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The process, sometimes referred to as a thermite process, consisted of combining UF4 with Mg 

metal in a steel reduction container, often referred to as a pot or a bomb. The material was 

heated until the following reaction occurred.

UF4 + 2Mg → U + 2MgF2

The reaction was exothermic so, once the ignition point was reached, the reaction proceeded 

rapidly throughout the reduction pot resulting in a molten mixture of metallic uranium and MgF2. 

The two molten substances separated due to different specific gravities then cooled and 

solidified. The solid uranium metal pooled in the bottom of the pot and the MgF2 solidified

above. The inside of the reduction pot was lined with refractory material in order to prevent the 

reaction from involving the steel reduction pot, as well as providing thermal insulation to protect 

the pot and to allow time for the reaction products to separate before they began to solidify. 

At Electromet, the refractory lining was fused dolomite that was placed in the pot as a fine 

powder between the inner walls of the pot and a mandrel. The mandrel was jolted to pack the 

dolomite into place around the sides and bottom of the pot. Once the UF4 and Mg mixture (the 

charge) was poured into the pot, additional dolomite was added to the top to complete the 

refractory envelope.

After firing, the pot was allowed to cool and then emptied. The process involved opening the pot 

then chipping and dumping the contents on a 4 mesh grate (1/4”). The MgF2 had solidified so it 

would consist of large “lumps” containing some uranium due to incomplete separation. This was 

known as C-1 slag or rich slag (meaning rich in uranium). The liner was not involved with the 

chemical reaction so it was largely still in a powder state and came out of the pot as such. 

Because some of the liner was in direct contact with the reaction, the liner did contain some 

uranium contamination. This material was known as C-2 slag, or lean slag or C-liner.

The C-1 slag was packaged and shipped to another site to reclaim the uranium contained in it. 

The C-2 slag, however, was considered too low in uranium concentration for recovery to be 

economically feasible.

3.1 Process at Hooker

Two process descriptions for the work at Hooker were found. Both are similar but do vary in 

some details. The first description comes from a “Data Sheet for Industrial Hazards”, dated 

December 8, 1944 (MED 1944). This document indicates 10 tons of material per month was 

processed and the material was 90% MgF and 10% CaO. The description of the process is:

“Slag is received in barrels containing about 500 lbs. The barrels are opened and the 

material is dumped on a conveyor belt which carries it up a ramp to one of the three 

digest tanks. 40 barrels are added to each tank. Waste HCl from the P-45 plant is 

passed into the digest tank and the pH is adjusted to 4.0 by the addition of water. After 

the tank has been filled, the contents are agitated for 20 hours. About once in two days a 

tank is emptied, which is sufficient turn-over to take care of waste HCl. At the 

completion of the digest the slurry is neutralized by dumping 100-lb. bags of lime into the 

tanks from an overhead platform, pumped to a plate and frame press, and filtered. The 
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filtrate is passed off into the sewer; the precipitate is washed several times and 

rebarreled. Slag is concentrated from about 1 lb. [of uranium] to 5 or 10 lbs. [of 

uranium] by weight.”

Another document (Thomas 1944) describes the testing performed on the material and 

development of the process used at Hooker including design calculations. The testing found that 

screening the slag through a 20 mesh screen would efficiently separate some rich slag. 

Therefore, the process was to screen the slag first and redrum the “lumps”. About 20% of the 

incoming slag was “lumps”. The material that made it through the 20 mesh screen would then be 

digested in a tank with the waist HCl. The design calculations were for 20 drum of screened slag 

per day weighing 275 pounds each. Also the operation was to run 26 days per month (6 days per 

week). 

While Thomas indicates the slag came in at a rate of 20 drums weighing 275 pounds each day, 

the other document implies 40 drums weighing 500 pounds constitutes a batch without any 

indication of the time frame. The incoming rate in Thomas would be equal to 71.5 tons per 

month while the MED document indicates the rate was 10 tons per month without indication of 

incoming or outgoing.

In order to determine the production rate at Hooker, three potential interpretations were 

developed.

1. Forty drums weighing 500 pounds each were brought in each day (MED description 

assuming daily)

2. Forty drums weighing 500 pounds each were brought in once per month (equal to 10 tons 

per month incoming slag)

3. Twenty drums weighing 344 pounds each were brought in daily (Thomas indicated the 

275 pound drums had already been screened so 275 pounds represent 80% of the 

incoming drum weight).

3.2 ElectroMet Slag Production

In order to evaluate the credibility of these interpretations, it is necessary to determine the 

amount of slag available from Electromet. Between 1943 and 1945, the MED produced 2969 

tons of uranium metal (AEC 1951). Both Mallinckrodt and Electromet were major producers

and it is reasonable to assume that Electromet produced half of this quantity (1485 tons).

A typical reduction bomb is described as being 40 inches long with a 10.125 inch inner diameter. 

A mandrel, tapered from 8.75 to 9 inches, is inserted into the bomb and used to tamp the 

dolomite powder into a lining (Spedding 1945, pg. 14) so the lining then has an average 

thickness of 0.625 inches. Assuming the same thickness for the top and bottom results in a 

lining volume of 823.5 cubic inches (13490 cubic centimeters). Assuming a density of 2 g/cc 

(Spedding 1945, Table 10), the liner would weigh 59.4 pounds. The bomb was filled with 168 

pounds of UF4 and excess magnesium metal for the reaction. The overall yield of uranium metal 

(after reduction and casting) was about 93% (Spedding 1945, pg. 54). Therefore, the 168 pounds

of UF4 would produce about 118.4 pounds of U metal. This results in a ratio of 0.5 pounds of 
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lining per pound of uranium metal. That implies Electromet could have produced 744 tons of 

lining. 

That estimate relies in part on the density of the lining. The density of a dry chemical is variable 

and dolomite has been reported to be anywhere from 55 pounds/ft3(0.88 g/cc) (NLA) to 2.88 

g/cc (Vulkan 2008, Table 4.47b). Since the dolomite is jolted into place it is packed and likely 

more dense than the 0.88 g/cc which is intended for determining storage capacity of bulk 

dolomite. That value would then be low for this application. The 2.88 g/cc reference is a 

dolomite brick after it is fired. Firing would normally fuse the brick into a single unit increasing 

its density. Therefore, that value would also not be appropriate for this application. Spedding 

(table 10 pg. 43) reported a packing density of 2 g/cc for electrically fused dolomite. Since that 

document discusses the dolomite in the context of uranium reduction, this appears to be an 

appropriate reference.

One estimate that does not depend on the density is to use the cost information in Spedding. The 

cost estimate indicated the liner cost 8.65 cents per pound of uranium produced. It also indicted 

the raw material cost 13.5 cents per pound of refractory. Unfortunately, it is not clear if this is 

the raw dolomite or fused dolomite. Spedding (pg. 42) indicated some dolomite was electrically 

fused at Electromet so Electromet had the capability of buying raw dolomite and fusing it on site. 

This process involved heating the dolomite to high temperatures to drive off the CO2 component 

leaving MgO and CaO. The CO2 accounts for about 48% of the raw dolomite weight. So the 

estimate could be indicating 13.5 cents per pound of raw dolomite which would be equivalent to 

25.9 cents per pound of fused dolomite liner. With these two interpretations, the cost based 

estimate results in a total liner production at Electromet of either 496 tons or 951 tons.

Several other reference are available for the amount of liner used in a reduction pot. The first 

(Huke 1944, pg. 15) is a report dated January 27, 1944 pertaining to the loss of material at 

Mallinckrodt. A mass balance for Plant 4 at Mallinckrodt indicates the material going into a 

reduction pot was 135 pounds of green salt (UF4), 55 pounds of liner and 24 pounds of 

magnesium. This equals 0.41 pounds of liner per pound of UF4. A second reference (Thayer 

1955) indicated the reduction pots used 0.432 pounds of liner per pound of UF4. A third 

reference (Electromet 1943, pg. 6) is a report discussing the development of the reduction 

process and mentions that for the chosen size of the reduction pot “the quantity of dolomite 

required was decreased from 0.7 pounds per pound of salt to 0.4 pounds”. In this case, “salt” is 

referring to green salt, a term for UF4. Using an overall metal yield of 93%, these three values 

(0.41, 0.432 and 0.4) would result in an estimated lining inventory at Electromet of 858 tons, 910 

tons and 842 tons respectively.

All the estimates above depend on the assumption that Electromet produced half of the MED’s 

uranium metal. An estimate that does not involve that assumption utilizes a 1946 document 

(Gates 1945 pg. 22) that lists the amount of raw materials consumed by Electromet during

normal operations. It indicates 110,000 pounds of electrically fused dolomite and 24,000 pounds 

of Kelly Island dolomite are necessary for 60 days of production. The Kelly Island dolomite 

would need to be electrically fused before use and that process would reduce the weight to 

approximately 52% of the original weight. Adjusting for this, and assuming 31 months of 
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operations between Electromet startup (4/1/1943) and Hooker shutdown (11/1/1945) produces an 

estimate of 950 tons of fused dolomite used at Electromet.

The estimates presented here range from 496 tons to 951 tons. However, two of these estimates 

are outliers. The 496 ton estimate assumes the dolomite purchased was raw dolomite and 

electrically fused on site. Gates however, lists electrically fused dolomite separate from Kelly 

Island dolomite. This could mean that most of the dolomite purchased was already electrically 

fused and the 496 ton estimate can be disregarded. The 744 ton estimate depends on the density 

of the packed dolomite liner. This parameter is variable and since estimates that do not depend 

on it are available, this value should be disregarded. That leaves estimates of 951, 858, 910, 842 

and 950 tons. These values involve different methods, parameters and references but produce 

reasonably good agreement. Also, the use of these estimates later in this document depends on 

an approximate value so a closely matched range is sufficient.

3.3 Mass Balance

A mass balance was performed to determine which of the interpretations in section 3.1 are 

credible. For this mass balance, parameters taken from the experimental and design document 

(Thomas 1944) were used and are listed below.

- The incoming slag is made up of 80% fines and 20% lumps

- The fines are assumed to be uranium contaminated fused dolomite (CaO MgO)

- The lumps are assumed to be uranium contaminated MgF2

- Uranium content in the fines = 0.84%

- Uranium content in dry concentrate = 9.87%

- Moisture content in concentrate = 41.4%

- Lumps are assumed to have the same uranium content as the dry concentrate

- These parameters result in a uranium content of 2.65% for the incoming slag

- Work consisted of 26 eight hour days per month

- Work period was 7/11/1944 to 11/1/1945 (~15.5 months)

The interpretations in section 3.1 differ by the incoming slag rate.

Interpretation 1 = 40 barrels weighing 500 pounds coming in 26 days per month

Interpretation 2 = 40 barrels weighing 500 pounds coming in 1 day per month

Interpretation 3 = 20 barrels weighing 344 pounds coming in 26 days per month

Using this information, a mass balance was calculated. Table 1 below shows the results of 

several parameters for each interpretation. Results are listed on a per month and total (entire 

project) basis.

Table 1: Mass Balances for Each Processing Interpretation

Table 1

Mass Balances for Each Processing Scenario

Parameter Scenario 1 Scenario 2 Scenario 3

% moisture in concentrate 41.4% 41.4% 41.4%

%U in fines 0.84% 0.84% 0.84%

% U in dry concentrate 9.87% 9.87% 9.87%
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Incoming # of drums per day 40 1.54 (avg) 20

Weight of each drum (pounds) 500 500 343.75

Fraction that are fines 0.8 0.8 0.8

% U in incoming 2.65% 2.65% 2.65%

Monthly Rate

Tons of incoming slag per month 260 10 89.375

Tons of fines per month 208 8 71.5

Tons of U per month 1.75 0.0672 0.60

Tons of concentrate (dry) per 

month 17.7 0.68 6.09

Tons of concentrate (wet) per 

month 30.2 1.16 10.4

Project Totals (assumes 15.5 months of operations)

Total tons incoming 4030 155 1385

Total tons fines 3224 124 1108

Total tons concentrate (dry) 274 10.6 94.3

Total tons concentrate (wet) 468 18.0 161

Interpretation 1 requires over 3000 tons of liner material to be processed at Hooker. Since the 

Electromet plant did not produce that much liner (section 3.2) it is clear that this interpretation is 

incorrect. This interpretation came from MED 1944 assuming the 40 drums weighing 500 

pounds each was a daily event. Interpretation 2 assumes that is a monthly event based on the 10 

ton per month rate in that document. However, when compared to the design criteria for the 

project (Thomas 1944), this rate is almost 9 times lower than the design rate. This is possible but 

not very credible unless there was a large change in direction between design and operation. For 

interpretation 3, the 10 ton per month rate in MED 1944 matches well with the 10.4 tons/month 

for the wet concentrate. Since the document does not specify if the 10 tons/month is wet or dry 

concentrate or slag, this is not a disqualifier for this interpretation. The total of 152 tons listed in 

Mears matches reasonably well with the 161 tons of wet concentrate produced. This document 

indicates the 152 tons processed is slag but it is possible this is just an error and it is really slag 

concentrate. The 152 tons processed is also in reasonable agreement with the 155 tons of slag 

associated with interpretation 2.

In conclusion, interpretation 1 is not possible while both interpretation 2 and 3 are possible. 

Interpretation 3 requires a belief that Mears was incorrect when it said 152 tons of slag was 

processed and it was actually slag concentrate. Interpretation 2 requires a belief that the amount 

of material actually handled was nearly 9 times less than the design capacity of the process. This 

document will therefore, assume that interpretation 3 is the best description of the production 

rate at Hooker.

3.4 Work Flow

Thomas (Thomas 1944) includes a cycle of operations that describes each step of the process and 

the time necessary to perform them. The cycle indicates 2 hours per 8 hour day is necessary to 

dump the slag barrels and an additional 2 hours necessary to dump and barrel the concentrate. 
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The remaining part of the day involved steps that do not involve handling the slag directly such 

as operating the filter press. 

Based on Thomas, this estimate will assume 2 hours per day was spent dumping incoming slag 

barrels and 2 hours per day was spent packing concentrate into barrels. 

DOE 1977 indicates the incoming slag was packaged in wooden barrels weighing 500 pounds. 

Wooden whiskey barrels were commonly used at the time for many purposes. 53 gallon wooden 

barrels are traditionally used for bourbon whiskey. This estimate will assume the slag was 

delivered in 53 gallon whiskey barrels.

Thomas indicated daily concentrate would be packaged in three 300 pound barrels. Thomas also 

indicated the density of the wet concentrate was 1.3 g/cc (82 pounds/ft3, Thomas 1944 pg. 5). 

300 pounds at 1.3 g/cc would occupy approximately 27.7 gallons of space. It is unlikely they 

only put 27 gallons of material into a 53 gallon barrel. More likely a smaller size was used for 

the concentrate. 27 CFR 25.11 indicates one barrel as a unit of measure is equal to 31 gallons. 

This seems to be a reasonable size to contain 27 gallons of material. Therefore, this estimate will 

assume the concentrate was packaged into 31 gallon barrels.

 

4.0 Internal Dose

The Secretary of Health and Human Services designated a class of employees at Hooker to be 

added to the Special Exposure Cohort. The class covers the period from July 1, 1944 to 

December 31, 1948 based on the inability to estimate the internal exposure with sufficient 

accuracy. The designation also indicated residual period exposures would be estimated using the 

techniques in the previous version of this Technical Basis Document. That estimate utilized the 

operational air concentrations. Together, this implies it was determined that the air concentration 

estimate was sufficiently accurate for estimating contamination levels but not for estimating 

operational airborne levels. 

Therefore, no internal dose estimate will be provided prior to 1949. Operational airborne 

concentrations will be estimated below as part of calculating internal and external exposures 

from contamination.

4.1 Operational Air Concentration

No data were found in the Site Research database related to occupational internal dose during 

MED work. The work performed at Hooker Electrochemical involved concentrating C-2 slag. 

Much of that work involved either liquid or material with a high moisture content which would 

result in little or no airborne activity. The one task involving dry material was the dumping of 

barrels of slag. The slag came directly from the nearby ElectroMet facility. Two air sample 

results from handling this material at ElectroMet were found. The first result was an average of 

an unknown number of samples taken on December 24, 1947, March 30, 1948 and May 14, 

1948. The average of the samples was 456 dpm/m3. The second result was an average of three 

samples taken between August 17th and the 19th of 1949. The average value was 398 dpm/m3. 

Work associated with these samples included shoveling the material into the barrels. 
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Since there are only two results and they were reported as averages, they provide little 

information about the variability of the data. Therefore, additional samples associated with 

handling slag were found at Mallinckrodt and Fernald. These samples are listed in Table 2.

These samples were used to determine the parameters of a lognormal distribution. The analysis 

resulted in determining a geometric standard deviation (GSD) of 2.43 and a geometric mean 

(GM) value of 187.7 dpm/m3. The 95th percentile of this distribution is 806 dpm/m3. Figure 1 

shows the individual data points along with the fit associated with these parameters.
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Table 2: Magnesium Fluoride Air Samples

Site Task Air 

Concentration 

(dpm/m3)

Comments SRDB 

reference

ElectroMet Loading slag into 

barrels and weighing 

456 Average of unknown 

number of samples

8917 pg 7

ElectroMet Shoveling slag into 

drums

398 Average of three 8930 pg 19

Mallinckrodt Slag Man 154 9340 pg 4

Mallinckrodt Slag handling 154 11553

Mallinckrodt Slag Man 77 9341 pg 5

Mallinckrodt Removing slag drum 237 9443 pg 19

Mallinckrodt Removing slag drum 60.8 9443 pg 19

Fernald BZ – dumping can of 

C-liner

247 34544

Fernald BZ – dumping can of 

C-liner

191 34544

Fernald BZ – dumping can of 

C-liner

255 34544

Fernald BZ – dumping can of 

C-liner

206 34544

Fernald BZ – dumping drum 

of C-liner

793 42627

Fernald BZ – dumping drum 

of C-liner

829 42627

Fernald BZ – dumping drum 

of C-liner

424 42627

Fernald BZ – dumping drum 

of slag outdoors

32 42628

Fernald BZ – dumping drum 

of slag outdoors

110 42628

Fernald BZ – dumping drum 

of slag outdoors

85 Value calculated from 

average, min and max

42628

Fernald BZ – dumping drum 

of slag outdoors

85 Value calculated from 

average, min and max

42628
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Figure 1: Air Sample Distribution

Drum dumping is the highest airborne causing evolution at Hooker but it was performed only 

two hours per day. The next highest airborne causing evolution would be the filtering and 

drumming of the concentrate after digestion. The remaining operations were performed in a 

liquid system. In order to determine an intake associated with filter operations, measurements 

associated with the digestion of uranium concentrates were considered. Digestion of 

concentrates involves many of the same basic steps as the concentration of slag at Hooker. A 

report by Christofano and Harris (Christofano 1960) determined the range of airborne activity 

associated with digesting uranium concentrates to be between 17 dpm/m3and 100 dpm/m3 with 

an average concentration of 40 dpm/m3. They also noted the uranium concentration in the 

incoming concentrate was 70% to 90% U3O8. Using the average (80%) equates to a uranium 

concentration of 68%. The concentrate being filtered at Hooker is 5.78% uranium. Adjusting 

the highest air concentration (100 dpm/m3) down to 5.78% uranium produces a uranium airborne 

concentration of 8.52 dpm/m3. 

The internal dose estimate for Hooker will assume individuals are exposed to slag dumping 25% 

of the time (2 hours per 8 hour workday) and the airborne concentration associated with filter 

operations the remaining 75% of the time. The 95th percentile of the slag distribution (806 

dpm/m3) will be used along with the bounding value (8.52 dpm/m3) for the filter operation. This 

produces an average airborne concentration of 208 dpm/m3. It is further assumed that the 

operators worked 8 hours per day, six days per week for 50 weeks per year resulting in 2400 

hours of work per year. 

This airborne concentration is used in the residual contamination section (Section 6) of this 

document to calculate the surface contamination value and the internal and external doses 

associated with it. No internal dose estimate will be made during the operational period based on 

the SEC designation.
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5.0 External Dose

No external dosimetry data were found related to occupational external dose at Hooker during 

the MED work. Therefore, external dose was modeled using the computer code MCNP. 

External dose associated with the incoming barrels of slag was modeled as well as with a barrel 

of uranium concentrate and surface contamination. 

5.1 Barrels

From Section 3, slag barrels are assumed to be 53 gallon wooden whiskey barrels while 

concentrate barrels are assumed to be similar except 31 gallon in size. Also, the slag is assumed 

to be 20% lumps made up of MgF2 with 9.87% uranium content and 80% fused dolomite with a 

chemical composition of equal parts CaO and MgO with 0.84% uranium content. The overall 

uranium content would be 2.65%. Concentrate was 41.4% moisture with the remaining content 

being MgF2 with 9.87% uranium making the overall uranium content of the concentrate 5.78%.

One source of 53 gallon whiskey barrels (Kentucky Barrels 2003) indicates the barrel is made 

with 1 inch thick oak wood and provides dimensions. These dimensions were used to model the 

barrel in MCNP then the dimensions were adjusted uniformly to achieve an internal volume of 

53 gallon. The same model was used for the concentrate barrel after the dimensions were 

adjusted to achieve an internal volume of 31 gallons.

The slag barrel was modeled so that 343.75 pounds of slag filled the barrel. This results in a 

density of approximately 50 pounds/ft3. This is reasonably close to one reference that indicates 

bulk dolomite has a density of 55 to 60 pounds/ft3(NLA). For the concentrate, the density of 1.3 

g/cc was used (82 pounds/ft3, Thomas 1944 pg. 5) and the material was assumed to fill the 31 

gallon barrel. This results in a drum with approximately 336 pounds of wet concentrate which is 

reasonable compared to the 300 pounds indicated in Thomas.

Photon radiation was calculated from both barrels at 1 foot and 1 meter distances. Direct photon 

radiation as well as bremsstrahlung photons were calculated and added. Beta radiation is largely 

attenuated by the sides of the barrel. However, the one centimeter and one foot dose rates above 

the unlidded barrel were calculated. One meter above the barrel was considered unrealistic. 

Beta radiation levels through the sides of the barrel were attempted. It was determined that it 

would be difficult to produce an accurate calculation of these levels but also determined that the 

level would be trivial compared to that above the barrel. Therefore, the levels above the barrel 

will be used in dose calculations and the one meter beta dose rate will be ignored.

Dose conversion coefficients listed in ICRP 1996 Table A.1 were utilized for photon dose rate 

calculations. Dose conversion coefficients from ICRP 1996 Table A.43 were utilized for beta 

dose rate calculation. The resulting dose rates are shown in Tables 3 and 4.
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Table 3: Slag Barrel External Dose Rates

Photons

(mr/hr)

Betas

(mrad/hr)

Contact N/A 2.03

1 foot 2.26E-02 0.467

1 meter 5.42E-03 N/A

Table 4: Concentrate External Dose Rates

Photons

(mrem/hr)

Betas

(mrem/hr)

Contact N/A 4.52

1 foot 4.21E-02 0.863

1 meter 9.18E-03 N/A

5.2 External Dose from Surface Contamination

Next the external dose rate from surface contamination was calculated again utilizing the 

computer code MCNP. The model assumed a large area of contamination (circle with a 100

meter diameter). The contamination was assumed to be evenly distributed over the area. The 

radioactive components of the contamination were assumed to be naturally enriched uranium in 

equilibrium with its short-lived decay products. The dose rate one foot from the surface was 

calculated assuming a contamination of 1 dpm/m2alpha activity. This produced conversion 

factors that could then be multiplied by the surface contamination values to obtain external dose 

rates. The result of these calculations is shown in Table 5.

Table 5: Surface Contamination External Dose Rates

Conversion factor Dose Rate

Photon 6.79E-10 mr/hr per dpm alpha/m2 1.90E-04 mr/hr

Beta 6.04E-08 mrem/hr per dpm alpha/m2 1.69E-02 mrem/hr

The surface contamination level was estimated by assuming the operational airborne activity was 

deposited with a velocity of 0.00075 m/s. The airborne activity used was the upper bound of the 

daily average activity from section 4.0 (208 dpm/m3). The airborne was assumed to deposit for 

30 days (TBD-6000) without any removal mechanism. This resulted in a surface contamination 

level of 404314 dpm/m2. This value was multiplied by the conversion factors in Table 5 to 

obtain the estimate of external dose rates due to surface contamination. The resulting dose rates 

are also contained in Table 5. 

All beta exposure is entered into IREP as electrons >15keV. Energy distribution of the photon 

exposure rate from surface contamination was also calculated using MCNP. The energy 

distribution was determined to be 80.2% <30keV, 12.3% 30 to 250 keV and 7.5% >250 keV. 

These values should be used in calculating photon dose.
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5.3 External Dose Summary

Operators are assumed to spend 2 hours per day (25%) emptying barrels of slag. A similar 

amount of time is assumed to be spent loading concentrate into barrels (Thomas 1944). 

Additionally, operators are assumed to be exposed to external radiation from surface 

contamination 100% of the time. Laborers are assumed to be in the area 100% of the time but 

not directly handle the material. As such, they are assumed to be exposed 100% of the time to 

external radiation from surface contamination. Supervisors are assumed to spend 50% of their 

time in the area but not directly handle material. Clerical or other individuals are assumed to be 

in the area 5% of the time but not directly handle material. 

While handling the material directly, operators are assumed to spend 50% of their time one foot 

from the barrels and the remaining 50% of the time one meter from the barrels. The operators’

hands are assumed be in contact with the material the entire time they are one foot from the 

barrels. The annual doses were calculated for photon dose, skin of the whole body (WB-skin) 

and the hands and forearms. The overall external dose estimates for operational periods are 

shown in Table 6.

Table 6: External Dose Summary

Photon

(mr/yr)

WB-Skin

(mrad/yr)

Hands and forearms

(mrad/yr)

Material Dose

Operators 23.8 399 1970

Contamination Dose

Operators 0.659 58.6 58.6

Laborers 0.659 58.6 58.6

Supervisors 0.329 29.3 29.3

Clerical 0.0329 2.93 2.93

The photon doses from material should be entered into IREP as 30keV to 250 keV photons with 

a constant distribution. Photon doses from contamination should be entered into IREP as a 

constant distribution with the energy distributed as 80.2% <30 keV, 12.3% 30 to 250 keV and 

7.5% >250 keV. The WB-skin and hands and forearms doses should be entered as electrons 

greater than 15 keV with a constant distribution. The 1944 and 1945 doses should be prorated to 

the fraction of the year the operation occurred based on a start date of July 11, 1944 and an end 

date of November 1, 1945.

6.0 Residual Contamination

For the purposes of this document, the residual contamination period at Hooker Electrochemical 

is considered to begin on November 1, 1945 and end on October 11, 1976. The end date is based

on the Residual Contamination report (NIOSH 2009) and the date of the radiological survey that 

concluded that no elevated levels of radioactivity were onsite (DOE 1977 pg 11). 

The external dose rates used during this period are the dose rates contained in section 5.2 from 

the surface contamination. 
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The internal dose rates are based on the surface contamination values derived in section 5.2

combined with a resuspension factor of 1x10-6 m-1. NUREG-1720 provides this value as the 

Nuclear Regulatory Commission’s recommendation of an appropriate resuspension factor for 

license termination screening. The recommendation indicates a resuspension factor of 1x10-6 m-1

is more realistic than the previous value of 1.42x10-5 m-1 and sufficiently conservative for 

screening analysis. In this analysis, the NRC noted a significant difference between those studies 

conducted in areas with freshly deposited contamination versus those involving “operating 

facilities or those undergoing decommissioning”. Since the NRC report was associated with 

decommissioning, they chose to not use those studies involving freshly deposited contamination. 

The basis for this decision was the assumption that any area undergoing decommissioning would 

likely be washed down. 

At Hooker, the majority of the airborne contamination (and thus the surface contamination) was 

located where the slag drums were emptied. This work was accomplished outdoors on a 

concrete pad near the railroad spur. As such, the contamination was exposed to the elements in 

western New York State. Wind, rain, and snow melt would quickly accomplish the same effect 

as washing down the area with a water hose. Therefore the resuspension factor from NUREG1720 appears to be applicable at Hooker. 

The surface contamination value is based on a bounding estimate of the airborne levels deposited 

for 30 days with no removal mechanisms. The surface contamination value is then a bounding 

value. Since both the internal and external exposure estimates are based on this bounding value, 

the dose estimated during the residual period will be entered into IREP as a constant. 

The internal and external values applicable to the residual period are shown in Table 7. 

Table 7: Residual Period Dose Summary 

Internal Dose

Job Category Years Nuclide Intake (dpm/calendar day)

All jobs 1949-1976 U-234 3.2

External Dose

Job Category Years Photons (mr/yr) Skin (mrem/yr)

Operators 11/1/1945-1976 58.6 58.6

Laborers 11/1/1945-1976 58.6 58.6

Supervisors 11/1/1945-1976 29.3 29.3

Clerical 11/1/1945-1976 2.93 2.93

All internal dose is entered into IREP as alpha radiation with a constant distribution. External 

photon dose should be entered into IREP as a constant distribution with an energy distribution of 

80.2% <30keV photons, 12.3% 30 to 250 keV photons and 7.5% >250 keV photons. External 

skin doses should be entered into IREP as a constant distribution of electrons >15keV. 
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7.0 Occupational Medical Dose

The War Department memo dated March 8, 1946 indicated the medical requirements included a 

pre-employment exam including a chest x-ray as well as a monthly blood count and monthly 

urinalysis. It also indicates there were no special exams and that this schedule was not adhered 

to after the first year of operation (Mears 1946). No other information regarding occupational 

medical dose specific to Hooker Electrochemical was found. Information to be used in dose 

reconstructions for which no specific information is available is provided in ORAUT-OTIB0006, the dose reconstruction project technical information bulletin covering diagnostic x-ray 

procedures. The assigned frequency should be only a pre-employment PA chest x-ray.
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8.0 References

AEC 1951, Atomic Energy Commission, The Production of Uranium Feed Material, May 22, 

1951, SRDB 4125 pg 77

Christofano 1960, The Industrial Hygiene of Uranium Refining, Emil Christofano and William 

B. Harris, November 1960, SRDB 15774

DOE 1977, U.S. Department of Energy, 1977, Formerly Utilized MED/AEC Sites Remedial 

Action Program, Radiological Survey of the Hooker Chemical Company, Niagara Falls, New 

York, Final Report, Washington, D.C., January 1977, SRDB 10797

DOE 1985, U.S. Department of Energy, 1985, Formerly Utilized Sites Remedial Action Report

Elimination Report for Occidental Chemical Corporation (Former Hooker Electrochemical 

Company) Niagara Falls, New York, Washington, D.C. SRDB 11002 pp. 58

DOE 2009, Office of Health, Safety and Security, EEOICPA web site. 

http://www.hss.energy.gov/healthsafety/fwsp/advocacy/faclist/findfacility.cfm

Dowling 1944, Dowling, Francis A., c. 1944, Completion Report, Construction of Hooker 

Electrochemical Company P-45 Plant, Contract No. W-7405-ENG-28, Tonawanda AreaManhattan District, SRDB 11002 pp. 102-112

Electromet 1943, Electro Metallurgical Company, Production Report on Tubealloy Metal by 

Electro Metallurgical Company, May 14, 1943, SRDB 112671

Gates 1945, Major M. E. Gates, Letter to Area Engineer, Madison Square Area, Attention: Mr. 

F. M. Belmore, Description of Uranium Producing Processes, October 17, 1945, SRDB 9442

Huke 1944, Letter from Frank Huke to the Area Engineer, Madison Square Area, Attention 

Major Canfield Hadlock, Safeguarding of Metal, January 27, 1944, SRDB 3996, pp. 9-18

ICRP 1996, International Commission on Radiological Protection (ICRP), Conversion 

Coefficients for use in Radiological Protection against External Radiation, Publication 74, 

Annals of the ICRP, 26 (3/4)

MCNP, MCNP6.1/MCNP5-1.60/MCNPX-2.70: Monte Carlo N-Particle Transport Code System 

Including MCNP6.1, MCNP5 1.60 and MCNPX 2.7.0 and Data Libraries, Los Alamos National 

Laboratory, Los Alamos, New Mexico. and Data Libraries, 

Mears 1946, Mears, B.J., 1946, memorandum to The District Engineer, “Medical Clearance on 

Terminated Madison Square Area Contracts,” Manhattan District, Oak Ridge, Tennessee, March 

8, 1946, SRDB 17125 pp. 29-30

MED 1944, Manhattan District, 1944, “Medical Section – Manhattan District, Data Sheets for 

Industrial Hazard Rating”, SRDB 16323 pp. 29-30
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MED 1945, Supplemental Agreement No. 7 between the United States of America and Hooker 

Electrochemcial Company, September 30, 1945, SRDB 21341 pp. 6-84

NIOSH 2009, National Institute for Occupational Safety and Health 2009, Report on Residual 

Radioactive and Beryllium Contamination at Atomic Weapons Employer Facilities and 

Beryllium Vendor Facilities. http://www.cdc.gov/niosh/ocas/pdfs/tbd/rescon/rcontam1206.pdf

NLA, National Lime Association, Lime Fact Sheet, Properties of Typical Commercial Lime 

Products, http://www.lime.org/documents/lime_basics/lime-physical-chemical.pdf

NUREG-1720, U. S. Nuclear Regulatory Commission, Re-evaluation of the Indoor 

Resuspension Factor for the Screening Analysis of the Building Occupancy Scenario for NRC’s 

License Termination Rule, June 2002

OCAS 2004, Office of Compensation Analysis and Support, Technical Information Bulletin: 

Estimation of Ingestion Intakes, Rev 0, OCAS-TIB-0009, April 13, 2004

ORAUT-OTIB-0006, ORAUT (Oak Ridge Associated Universities Team), Technical 

Information Bulletin: Dose Reconstruction from Occupationally Related Diagnostic X-Ray 

Procedures, Rev 03 PC-1, December 21, 2005.

Olotka, 1979, Letter from F.T. Olotka to William E Mott regarding review and comments of a

March 1979 letter to J Gallery, April 18, 1979, SRDB 11002 pp. 39

Spedding 1945, F. H. Spedding, H. A. Wilhelm, W. A. Keller, The Production of Uranium By 

The Reduction of UF4 by Mg, June 26, 1945, Ames Laboratory, CT-2712, SRDB 112651

TBD 6000, Division of Compensation Analysis and Support, Site Profiles for Atomic Weapons 

Employers that Worked Uranium Metal revision 1, June 17, 2011

Thayer 1955, Letter from Harold E. Thayer to F. H. Belcher, Capacity Slag Grinding Plant, May 

13, 1955, SRDB 4012

Thomas 1944, W. G. Thomas, Technical Report on Concentration of C-2 Slag, M-4562, 

February 17, 1944, SRDB 127827

Tybout 1944, Memorandum from Richard A. Tybout to Col. Stafford L. Warren, Work Report 

for September 1944, October 4, 1944, SRDB 17273 pp. 14-18

Vulkan 2008, Vulkan Verlang 2008, Gerald Routskchka, Hartmut Wuthnow (Editors), Pocket 

Manual, Refractory Materials, Design Properties Testing, 3rd Edition, 

http://books.google.com/books?id=0ugkNtlWKWEC&pg=PA218&lpg=PA218&dq=fused+dolo

mite&source=bl&ots=tJuJUEusZz&sig=xTNh9leiCuZaiBdNupNzlTzWT0&hl=en&sa=X&ei=PMA4UdfBK9Co0AHEl4CgBA&ved=0CDAQ6A

EwAA#v=onepage&q=fused%20dolomite&f=false
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Young 1985, Charles D. Young, Update of Responses to Hooker (OCC) Interrrogatories, 

February 12, 1985, SRDB 11002 pp. 63-84