Draft 

ADVISORY BOARD ON 

RADIATION AND WORKER HEALTH 

National Institute for Occupational Safety and Health

REVIEW OF THE NIOSH TECHNICAL BASIS DOCUMENT 

FOR THE HOOKER ELECTROCHEMICAL COMPANY, 

DCAS-TKBS-0009 

Contract No. 200-2009-28555 

SCA-TR-SP2013-0034, Rev. 0 

Prepared by 

William C. Thurber 

S. Cohen & Associates 

1608 Spring Hill Road, Suite 400 

Vienna, VA 22182 

March 2013 

Disclaimer 

This document is made available in accordance with the unanimous desire of the Advisory Board on 

Radiation and Worker Health (ABRWH) to maintain all possible openness in its deliberations. However, 

the ABRWH and its contractor, SC&A, caution the reader that at the time of its release, this report is predecisional and has not been reviewed by the Board for factual accuracy or applicability within the 

requirements of 42CFR82. This implies that once reviewed by the ABRWH, the Board’s position may 

differ from the report’s conclusions. Thus, the reader should be cautioned that this report is for 

information only and that premature interpretations regarding its conclusions are unwarranted.
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Document No. 

SCA-TR-SP2013-0034 

Effective Date: 

 Draft – March 28, 2013 

S. COHEN & ASSOCIATES: 

Technical Support for the Advisory Board on Radiation 

& Worker Health Review of 

NIOSH Dose Reconstruction Program Revision No. 

0 (Draft) 

REVIEW OF THE NIOSH TECHNICAL BASIS 

DOCUMENT FOR THE HOOKER 

ELECTROCHEMICAL COMPANY, DCAS-TKBS-0009 

Page 2 of 33 

Task Manager/Lead Author: 

______________________________ Date:____________ 

William C. Thurber, M.S. 

Supersedes: 

N/A 

Project Manager: 

______________________________ Date:____________ 

John Stiver, MS, CHP 

Peer Reviewer(s): 

 John Mauro 

 John Stiver 

 

Record of Revisions 

Revision 

Number 

Effective 

Date Description of Revision 

0 (Draft) 03/28/2013 Initial issue 
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TABLE OF CONTENTS 

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

1.0 Statement of Purpose ...........................................................................................................6 

2.0 Introduction..........................................................................................................................7 

3.0 Review of Hooker Electrochemical Technical Basis Document, DCAS-TKBS-0009 .......9 

3.1

.........................................................................................................9 

Review of Section 3.0 “Process Description” and Section 3.1 “Uranium

Concentration”

3.2 Review of Section 3.2 “Monthly Production Rate”...............................................12 

3.3 Review of Section 4.0 “Internal Dose”..................................................................13 

3.4 Review of Section 5.1 “Slag Barrel” and Section 5.2 “Concentrate Barrel”.........15 

3.5 Review of Section 5.3 “External Dose from Surface Contamination”..................16 

4.0 Reconciliation of Prior SC&A Findings............................................................................17 

5.0 Use of Surrogate Data........................................................................................................23 

6.0 Summary............................................................................................................................24 

References......................................................................................................................................25 

Appendix A: Dust Samples Used by SC&A to Calculate Internal Exposures.............................28 

Appendix B: Reproduction of Slag Plant Operating Instructions.................................................31 

Appendix C: Quantity of C-2 Slag Generated per Ton of Uranium Metal Produced...................33 
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ACRONYMS AND ABBREVIATIONS 

Advisory Board, Advisory Board on Radiation and Worker Health 

ABRWH, or Board 

AEC Atomic Energy Commission 

AMAD activity median aerodynamic diameter 

AWE Atomic Weapons Employer 

BZ breathing zone 

CaO calcium oxide 

CFR or C.F.R. Code of Federal Regulations 

DCAS Division of Compensation Analysis and Support 

dpm/m3 disintegrations per minute per cubic meter 

DWA daily weighted average 

ElectroMet Electro Metallurgical Company 

ER Evaluation Report 

FGR Federal Guidance Report 

g/cm3 grams per cubic centimeter 

g/L grams per liter 

GM geometric mean 

GSD geometric standard deviation 

HCl hydrochloric acid 

Hooker Hooker Electrochemical Company 

ICRP International Commission on Radiological Protection 

keV kilo electronvolt 

kg kilogram 

LOOW Lake Ontario Ordnance Works 

m meter 

m3

/hr cubic meter per hour

MCNPX Monte Carlo N-Particle eXtended 

MCW Mallinckrodt Chemical Works 

MED Manhattan Engineer District 

Mg magnesium 

MgF2 magnesium fluoride 

MgO magnesium oxide 
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NOTICE:

mR/hr milliRoentgen per hour 

mrem millirem 

mrep/hr millirep per hour 

m/s meter per second 

NIOSH National Institute for Occupational Safety and Health 

ORAUT Oak Ridge Associated Universities Team 

pCi picoCuries 

pH - log H+ concentration 

R or r roentgen 

rem Roentgen equivalent man 

SC&A S. Cohen and Associates (SC&A, Inc.) 

SEC Special Exposure Cohort 

SRDB Site Research Database 

TBD Technical Basis Document 

U uranium 

UF4 uranium tetrafluoride 

μm micrometer
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1.0 STATEMENT OF PURPOSE 

The purpose of this report is to provide a critical review of the National Institute for 

Occupational Safety and Health (NIOSH) Technical Basis Document for Hooker 

Electrochemical Company, DCAS-TKBS-0009 (NIOSH 2011b). In this report, we assess the 

merits and technical basis of the data and guidance to be used for dose reconstruction. This 

review was authorized by the Advisory Board on Radiation and Worker Health (Advisory Board 

or ABRWH) Subcommittee on Procedures Review at its January 2013 meeting. 

In this report, SC&A also provides a critique regarding whether or not NIOSH has appropriately 

addressed in NIOSH 2011b findings from an earlier SC&A review of the original Hooker site 

profile, Appendix AA of TBD-6001 (SC&A 2010), and the Special Exposure Cohort (SEC) 

Petition Evaluation Report (ER) for Hooker (NIOSH 2010). Review of the ER findings is 

equally relevant, since many of SC&A’s findings on the ER were also tied to Appendix AA.
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2.0 INTRODUCTION 

In 2007, NIOSH issued the original site profile for the Hooker Electrochemical Company in 

Niagara Falls, New York (Battelle 2007) as Appendix AA to Battelle-TBD-6001, Site Profiles 

for Atomic Weapons Employers that Refined Uranium and Thorium (Battelle 2006). As an 

appendix to TBD-6001, the Hooker site profile relied heavily on the parent document for dose 

reconstruction guidance. Based on a May 2010 request by the Advisory Board, SC&A 

performed a review of Appendix AA and reported 10 findings (SC&A 2010). These findings are 

summarized in Section 4.0, along with a discussion regarding the extent to which these original 

findings have now been resolved. It should be noted that several of these findings related to 

problems with the parent document TBD-6001 upon which much of Appendix AA was based. 

TBD-6001 was subsequently cancelled by NIOSH and alternate modeling approaches were used 

in revising Appendix AA. 

At about the same time as the Advisory Board made its request to SC&A to review 

Appendix AA, NIOSH issued an ER on Hooker Electrochemical Petition SEC-00141 (NIOSH 

2010). SC&A was not initially tasked with reviewing the ER on Petition SEC-00141; however, 

as noted in its review of Appendix AA (SC&A 2010): 

SC&A was not tasked with a review of the petition evaluation report; however, as 

we have done in the past in similar situations (e.g., our review of the United 

Nuclear Corporation site profile), we provide some initial impressions regarding 

possible SEC issues, based on reading the petition and the evaluation report. A 

more detailed review of the petition and evaluation report will be performed if so 

authorized by the ABRWH.

Subsequently, at the TBD-6001 Work Group Meeting held in Cincinnati, Ohio, on November 4, 

2010, SC&A was requested by the Work Group to prepare a focused review of the NIOSH 

Petition Evaluation Report for the Hooker Electrochemical Atomic Weapons Employer (AWE) 

site (NIOSH 2010). Since the ER contained new information developed since Appendix AA was 

issued in 2007, the Work Group felt that a focused review of this new information was needed. 

In response to this tasking, SC&A provided the focused review of the ER in January 2011 

(SC&A 2011a). SC&A had nine findings based on its review of the Hooker ER. These findings 

are also summarized in Section 4.0, along with a discussion addressing the extent to which these 

nine ER findings have also been resolved. 

After the 2010 SC&A review, NIOSH converted Appendix AA to a stand-alone site profile or 

technical basis document (TBD) published on April 4, 2011 (NIOSH 2011a) and issued a 

revision to that document on June 17, 2011 (NIOSH 2011b). The changes made, according to 

NIOSH 2011a, were: 

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 [sic] review comments. 
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NOTICE:

Similarly, with regard to NIOSH 2011b: 

Revision initiated to correct errors in Tables 2, 3, and 6 [of NIOSH 2011a]. 

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. 

In the ensuing sections of this report, SC&A documents its review of the Technical Basis 

Document for Hooker Electrochemical Company, Rev. 1 (NIOSH 2011b) and discusses the 

extent to which prior findings regarding NIOSH documents related to Hooker have been 

adequately addressed. 

Since NIOSH 2011b uses surrogate data, the appropriateness of this usage, as judged against the 

criteria developed by the ABRWH, is discussed in Section 5.0.
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3.0 REVIEW OF HOOKER ELECTROCHEMICAL TECHNICAL BASIS 

DOCUMENT, DCAS-TKBS-0009 

During the course of this review, SC&A uncovered some new information, which was not 

considered by NIOSH and presents a somewhat different picture of what could have occurred at 

Hooker. The new information is a February 1944 report describing laboratory work done at 

Hooker to develop the C-2 slag concentration process and size process equipment for the 

leaching operation that began in July 1944 (Thomas 1944). In the discussion that follows, 

SC&A contrasts the process information based on the laboratory work (Thomas 1944) with the 

process information derived from MED 1944. As will be described, the information in MED 

1944 is ambiguous regarding the uranium content of the slag and the processing rate through the 

acid leaching operation. SC&A’s review here follows the sequence of topics as presented in the 

Hooker Electrochemical TBD (NIOSH 2011b). 

3.1 REVIEW OF SECTION 3.0 “PROCESS DESCRIPTION” AND SECTION 3.1 

“URANIUM CONCENTRATION” 

The Hooker Electrochemical Company (Hooker) in Niagara Falls, New York, processed C-2 slag 

from July 11, 1944, to January 15, 1946 (NIOSH 2011b, Section 2.0). The operations at the 

Hooker facility involved treatment of C-2 slag from the nearby Electro Metallurgical Company 

(ElectroMet) with hydrochloric acid (HCl) to increase the uranium content. The C-2 slag from 

ElectroMet was a byproduct of the bomb reduction process, in which uranium tetrafluoride was 

reacted with magnesium (Mg) to produce uranium metal. Dolomite was used as the bomb liner 

at that point in time (NIOSH 2011b).1 The dolomite was high-fired or fused, resulting in a 

product with the approximate formula CaO·MgO. The HCl was excess acid produced at Hooker 

under an Atomic Energy Commission (AEC) contract as a byproduct from the non-radioactive 

P-45 chemical process. 

In the bomb reduction process, several different “slags” were apparently produced. The bomb 

liner was fused dolomite, which was tamped into the bomb between the inner surface of the 

bomb and a mandrel. After the mandrel was withdrawn, the charge of Mg plus UF4 was inserted 

into the cavity. During the reduction process, both reaction products (U and MgF2) were molten 

and separated by gravity into distinct layers. The products were the uranium derby, the MgF2

slag, and the decomposed liner slag, which were physically separated from one another. 

Obviously, the separations were imperfect, so each product would be contaminated by the other 

two products. The spent liner was referred to as C-liner or C-slag. According to Thomas (1944), 

the reaction slag was divided into two parts; (1) C-1 slag, which was +4 mesh lumps containing 

5%–10% U, and (2) C-2 slag, which was the -4 mesh material containing 0.5%–3% U. ORAUT 

2005 (Table 4) mentions C-1 scrap, but provides no insight into its origin or composition. It is 

also not clear whether or not MgF2 slag and C-1 slag are somehow related. 

C-2 slag from ElectroMet was shipped to Hooker by rail in wooden barrels (DOE 1977, MED 

1944). Each barrel was filled with 500 lbs of slag (reduction bomb liners) with the 

“approximate” composition of “90% MgF [sic] and 10% CaO, plus 1% X” (MED 1944, p. 29). 

1

 After 1949, recycled MgF2 was used as the bomb liner. 
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We note that the correct chemical formula for magnesium fluoride is MgF2 and that “X” was 

used as code for uranium. 

The barrels were opened and the contents were dumped onto a 20-mesh screen,2

 with the 

undersize being conveyed by a bucket elevator to one of three wooden digestion tanks (MED 

1944, although DOE 1985 says that 4 tanks were used). Oversize (+ 20 mesh) material from the 

screening operation was drummed and returned to Manhattan Engineer District (MED) control. 

According to Thomas (1944), the oversize contained 8 times as much uranium as the -20 mesh 

fraction and accounted for about 20% of the as-received slag. 

After the undersize from 40 barrels of slag was loaded into a 13-ft diameter by 11-ft high 

wooden digester tank (Dowling 1944, p. 112; MED 1944, p. 30), HCl was added and the pH was 

adjusted to 4.0 with water additions (MED 1944).3

 Digestion of the agitated slurry continued for 

about 20 hours (MED 1944). Operators standing on platforms above the tanks then added lime 

from 100-lb bags to neutralize the slurry (MED 1944). The neutralized slurry was pumped to a 

plate and frame filter press, where the filtrate was collected and discharged into a sewer. The 

filter cake was then washed several times, and was re-drummed and shipped by rail to MED 

control (MED 1944). The turnover rate for a digester tank was stated to be once every 2 days 

(MED 1944). 

There is some uncertainty as to the uranium content and composition of the slag. As noted 

above, the uranium content is stated on page 29 of MED 1944 as 1%. However, on page 30 of 

MED 1944, it is stated that, “slag is concentrated from about 1 lb to 5 or 10 lb by weight.” If the 

barrel contained 1 lb of uranium in 500 lbs of slag, then the initial composition would be 0.2% 

(as assumed in NIOSH 2010, NIOSH 2011a, NIOSH 2011b, and SC&A 2010), not 1%, as stated 

in MED 1944 (p. 29). 

NIOSH (2011b) addressed the question as to whether the slag contains 0.2% U or 1% U, since 

both values appear in MED 1944. NIOSH notes that similar slag produced at Mallinckrodt 

Chemical Works (MCW) during the time when dolomite was being used as a bomb liner 

contained 0.3% U. NIOSH also argued that: 

Lastly, if the incoming material had a uranium concentration of 1%, the Hooker 

process description does not appear to make sense. A 1% concentration would 

equate to 5 pounds of uranium in 500 pounds of slag. If that were true, the 

mention of one pound of uranium in the description makes no sense. Also stating 

that the slag was concentrated to 5 pounds would make no sense.

However, Thomas (1944) states that the C-2 slag obtained from ElectroMet for Hooker process 

development contained 0.84% U, a value similar to the 1% X cited on page 29 of MED 1944. 

Thomas further states that the wet filter cake contained 5%–6% U and about 40% moisture. 

Given this information, the statement in MED 1944 that “slag is concentrated from about 1 lb to 

5 or 10 lb by weight” can be interpreted as meaning lbs of U per 100 lbs or concentration from 

2

 Screen opening – 0.0335 in. 

3

 We note that the September 12, 1944 Outline for Operating C-2 Slag Plant states that the pH was 

adjusted to 5. See Appendix B. 
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1% to 5%–10% U. With this interpretation, the compositions on both page 29 and page 30 of 

MED 1944 are consistent within that document and with Thomas 1944. 

The information in Thomas 1944 also brings into question whether the nominal slag composition 

of “90% MgF [sic] and 10% CaO, plus 1% X” is correct. Thomas (1944) states that the “bulk of 

the C-2 slag is magnesium oxide and calcium oxide.” The goal of the Hooker process was to 

increase the uranium content in the slag by dissolving away some of the unwanted constituents. 

According to the September 12, 1944, Outline for Operating C-2 Slag Plant, “the fines are 

dissolved in acid to remove lime.” If the feed stock contained only 10% CaO, it would not be 

possible to increase the uranium concentration from 1 lb to 5 to 10 lbs by weight through acid 

leaching of the CaO (and MgO) alone. It is possible that some of the MgF2 might also be 

dissolved during digestion in HCl. However, the solubility of MgF2 is reported to be only 3 g/L 

at pH 4 and 25°C (Johnson et al. 1954). At this solubility limit, less than 2% of the MgF2 could 

be removed. If the solution pH was 5, consistent with the conditions stated in the September 12, 

1944, Outline for Operating C-2 Slag Plant, the solubility of MgF2 is even lower – about 1 g/L. 

Johnson et al. 1954 also observed that the solubility of MgF2 decreased in the presence of Ca+2

ions. 

To increase the uranium concentration from 0.2% to 1% (or from 1% to 5%) would require that 

80% of the mass of the C-2 slag be dissolved, which means that the incoming slag would need to 

contain at least 80% CaO+MgO. Is this composition reasonable or possible? Consider the 

simplified chemical reaction: 

 

UF4 + 2Mg → U + 2MgF2 

Each kilogram of U produced will also produce 0.52 kg of MgF2 and consume 1.32 kg of UF4. 

The mass ratio of liner to UF4 can be estimated from Spedding et al. 1945 to be 0.54 (see 

Appendix C), so the mass of liner per kg of U produced is 0.71 kg. Assuming that the C-2 slag 

contained 20% MgF2, the mass of slag (liner plus 20% MgF2) would be 0.89 kg per kg of U 

produced and would contain 80% CaO+MgO. 

As previously noted, Thomas (1944) states that the “bulk of the C-2 slag is magnesium oxide and 

calcium oxide” and there is some evidence that separation of the MgF2 from the balance of the 

slag was practiced. At MCW, “derby slag was scalped or cut off the derby and separated into an 

MgF2 part and a C-liner part” (ORAUT 2005, Table 4). 

Spedding et al. (1945) provided additional contemporaneous information on the separation of 

MgF2 and liner. They note in Section 2.7: 

 

The bomb was removed from the cooling spray to a room equipped with a pit in 

the floor covered with grating made of 1⁄4” steel bars separated by 1⁄4" spaces. 

The pit was vented from the bottom by ducts leading to the main exhaust fan of the 

building. In emptying the bomb the cover was removed from the bomb, the side 

wall chipped down by a pneumatic chisel similar to a concrete chipper, the loose 

material dumped on the grating. The bomb was placed mouth downward on a 

pneumatic jolter and jolted until the ingot of metal was loosened and fell to the 
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floor. The remaining wall or liner material was chiseled loose and all liner 

material and slag were swept onto the grating which acted as a sieve permitting 

the 1⁄4" and finer material to pass into the barrel or drum below the screen. This 

product consisted chiefly of liner material, CaO or MgO, poor in both fluorine 

and uranium. Larger pieces, including most of the slag or MgF2, were removed 

to a chute in the cover of an adjacent pit and dropped into a second container. 

This product contained most of the unrecovered uranium 

If this type of separation was practiced at ElectroMet or if -20 mesh fraction from the screening 

at Hooker was enriched in CaO+MgO, then the digester feed could contain sufficient acidsoluble components. 

Based on the information presented here, it is plausible to assume that the concentration of 

uranium in the incoming slag and in the resultant concentrate is at least five times higher than 

assumed in the TBD. 

Another factor to consider is estimating the external dose from slag handling. The +20 mesh 

fraction, which was not subject to acid digestion, but did require handling, amounts to about 20% 

of the slag mass and contains 9% U (Thomas 1944). The contribution from this higher uranium 

content material needs to be included in the external exposure estimate. 

Finding 1. NIOSH should review the assumptions regarding the composition of the incoming 

slag and the outgoing concentrate in light of the new material provided in Thomas 1944. 

According to MED 1944, the barrels of feedstock contain about 500 lbs of slag, while Thomas 

(1944) uses a value of 275 lbs. If the bulk of the slag is CaO+MgO, a 50-gallon barrel4

 would 

contain about 310 lbs of slag, assuming a bulk density of 55 lbs/ft3 for dolomitic lime 

(http://www.lime.org/documents/lime_basics/lime-physical-chemical.pdf). Barrels with lower 

slag content would result in lower external exposures per unit time, but exposures times would 

be longer due to increased barrel handling, so the net result should be about the same regardless 

of the barrel mass loading. 

3.2 REVIEW OF SECTION 3.2 “MONTHLY PRODUCTION RATE” 

NIOSH (2011b) cites data sources indicating that the monthly production rate was 10 tons per 

month (MED 1944), and that total production was 152 tons over the life of the Hooker project 

(Mears 1946), but notes that some ambiguity exists as to whether these quantities refer to 

incoming slag or outgoing concentrates. NIOSH estimated that ElectroMet could have produced 

777 tons of slag through the end of 1945. Of this tonnage, some was apparently shipped to the 

Lake Ontario Ordnance Works (LOOW) for storage, and any oversized slag shipped to Hooker 

would not have been put through acid leaching. They note that, if the 10 tons per month referred 

to concentrate rather than slag, then 50 tons per month of slag would need to have been 

processed to increase the uranium content from 1 lb to 5 lbs. Over 18 months, this would require 

more feedstock (i.e., 900 tons) than was produced by ElectroMet. On this basis, NIOSH 

 4

 Mallinckrodt used 50-gallon whiskey barrels to package C-2 scrap (ORAUT 2005, Table 4). 
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concluded that the documented production rates and quantities referred to slag rather than 

concentrates. 

The ElectroMet slag production estimate of 777 tons made by NIOSH appears to be low. From 

April 1943 through August 1946, the average rate of uranium production at ElectroMet was 

44 tons/month (NYOO 1951). Since the Hooker work ended in January 1946, the maximum 

amount of C-2 slag available for processing at Hooker (April 1943 through December 1945) 

would have been 1,031 tons (33 months × 44 tons U/month × 0.71 tons slag/ton U), or about 

33% more than estimated by NIOSH. Assuming that the 152 tons cited by Mears (1946) was 

concentrate rather than incoming slag, the average concentrate production over the 18-month life 

of the Hooker project would be 8.4 tons/month. If the uranium concentration increased from 1% 

in the C-2 slag to 5% in the concentrate, then the monthly slag feed to the process would be 

42 tons/month, or 760 tons over the project life. Since we estimate that 1,031 tons of slag was 

available from ElectroMet, allowing for 20% oversize that was not acid-leached would leave 

825 tons. Thus, there should be sufficient C-2 slag to supply a 42-ton/month requirement, cover 

removal of oversize from processing, and provide for some slag storage at LOOW. 

The Hooker facility included three digester tanks, and the turnover rate per digester was about 

2 days (MED 1944). Thus, the plant had the capacity to process about 45 batches per month. It 

is puzzling why a plant of this size would be built if the processing rate was only one batch per 

month. In addition, we note from the September 12, 1944, Outline for Operating C-2 Slag Plant 

(Appendix B) that: 

IT IS MOST IMPORTANT THAT ALL THE DISPOSAL ACID BE USED FOR C-2 

SLAG. Each hour that acid runs to the lime pit is wasted time for the slag plant. 

The work SHOULD be planned with this in mind. 

It can be inferred from this quotation that there was little storage capacity for HCl at Hooker and, 

if the acid could not be used promptly to treat slag, it was sent to a neutralization pit. This 

information suggests that the Hooker plant was intended to handle considerably more than one 

batch of slag per month. 

Information in Thomas 1944 supports the idea that the input to the Hooker process was more 

than 10 tons per month. Thomas notes that the availability of HCl at Hooker was sufficient to 

concentrate 65 to 80 tons of slag per month. In addition, equipment was sized for an 80-ton per 

month acid leaching plant at Hooker. 

Finding 2: NIOSH should re-examine its position that external exposures were based on slag 

input to the leaching process of 10 tons per month. It is possible that external exposures are 

understated by a factor of about 5. 

3.3 REVIEW OF SECTION 4.0 “INTERNAL DOSE” 

Since there were no air monitoring data from Hooker, NIOSH collected surrogate data on C-2 

slag handling from ElectroMet, MCW, and Fernald. These data are summarized in Table 1 of 

the TBD. NIOSH fit these data to a lognormal distribution and determined that the geometric 
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mean (GM), geometric standard deviation (GSD), and 95th percentile values were 187.7 dpm/m3, 

2.43, and 806 dpm/m3, respectively. SC&A verified these metrics. 

The data in Table 1 of NIOSH 2011b were selected from a larger dataset developed by NIOSH 

and summarized in Tables 6-1, 6-2, and 6-3 of NIOSH 2010. NIOSH eliminated some of the 

data from the NIOSH 2010 tables in creating Table 1, based on judgments as to the relevance to 

Hooker of some of the surrogate slag handling data. SC&A reviewed the available data and 

concluded that some of the data excluded by NIOSH should be added to the Hooker dataset. 

Using this revised dataset (see Appendix A), SC&A determined that the GM was 95.1 dpm/m3, 

with a GSD of 3.53, and the 95th percentile was 759 dpm/m3. These values are similar to those 

calculated by NIOSH using a different dataset. Based on this analysis, it appears the TBD values 

needed to estimate internal dose are reasonable and claimant favorable. 

As discussed above, NIOSH assumed that slag handling occurred 5% of the time and assumed 

that the operators were exposed to the 95th percentile dust levels (i.e., 806 dpm/m3). For the 

remainder of the working time each month, it was assumed that the worker was exposed to dust 

levels representative of filtration of uranium concentrates. Christofano and Harris (1960) cite a 

range of 17 to 100 dpm/m3

 for the daily weighted average (DWA) exposure when acid-digesting 

uranium concentrates (avg. 68% U). Using the upper limit of 100 dpm/m3 DWA and scaling this 

to a 2% concentrate results in a DWA exposure from processing C-2 slag of 2.94 dpm/m3

 for 

95% of the working period. The average airborne concentration was determined to be 

43.1 dpm/m3 (806 × 0.05 + 2.94 × 0.95). This general approach for establishing dust levels is 

reasonable, assuming that slag handling occurs 5% of the time and that the concentrate contains 

2% U. However, as discussed in Section 3.2 above, we question whether 5% is the appropriate 

estimate of exposure time for handing slag. In the cost estimate for the proposed Hooker plant, 

Thomas (1944) assumed that one man would be required per day (48 hours/week) to load and 

unload barrels for an 80-ton per month operation. This would be somewhat reduced if the 

operating rate was 42 tons per month of slag. We also question whether the concentrate 

contained only 2% U. 

Finding 3: The basis for assuming that internal exposure from slag dust occurred 5% of the 

time needs to be re-examined, as does the assumption that the concentrate contained 2% U. It 

appears that the exposure time is understated by about a factor of 5 and the amount of 

uranium in the concentrate is understated by at least a factor of 2.5. 

NIOSH estimated that the inhalation exposure was 340 pCi/calendar-day (43.1 dpm/m3 × 

1.2 m3/hr × 8 hr/day × 300 work-days/365 calendar-days). NIOSH also estimated that the 

ingestion exposure was 5.9 dpm/calendar-day using guidance in OCAS-TIB-009 (OCAS 2004). 

The TIB-009 guidance specifies that the daily ingestion intake is 0.2 times the airborne activity, 

or 8.62 dpm/work-day (0.2 × 43.1). Apparently, NIOSH adjusted this to a calendar-day basis 

assuming 250 work-days per year (8.62 × 250/365 = 5.9 dpm/calendar-day). For consistency 

with the calculation of inhalation intakes, we believe that the correct value should be 

7.1 dpm/calendar-day (8.62 × 300/365). While the difference is trivial in terms of dose received 

by an AWE worker, values in the TBD should be consistent and accurate. 
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Finding 4: NIOSH should review the ingestion intake to ensure that it is calculated in a 

manner consistent with calculation of the inhalation intake. 

3.4 REVIEW OF SECTION 5.1 “SLAG BARREL” AND SECTION 5.2 

“CONCENTRATE BARREL” 

NIOSH performed MCNPX calculations to estimate photon and beta doses at various distances 

from a barrel of slag (0.2 wt% U) and a barrel of concentrate (2 wt% U). Results of these 

calculations are presented in Tables 2 and 3 of the TBD and are summarized in Table 3-1 here. 

We note that photon exposure is expressed differently in Table 2 and Table 3. Both tables 

include the phrase “External Dose Rate” in the table title. However, the units of measure for 

photons in Table 2 are mR/hr, while in Table 3 the units of measure are mrem/hr. The text in 

Section 5.1 states that: 

MCNPX was utilized to calculate the dose rate from direct photons and 

bremsstrahlung x-rays at a distance of one foot and one meter from the barrel. 

Dose conversion coefficients listed in ICRP 1996 Table A.1 were utilized for this 

calculation. 

Based on this information, one can conclude that the units of measure in Column 2 of Table 2 

should be mrem/hr not mR/hr. This distinction is important, because it can have a significant 

impact on selecting organ dose conversion factors from OCAS-IG-001 (OCAS 2007). 

Finding 5: NIOSH should confirm that the correct units of measure are cited in Tables 2 and 

3. 

SC&A independently performed MCNPX calculations for a barrel of slag, which were 

summarized in Appendix A of SC&A 2011a. Based on our interpretation of the available 

documents, we assumed that the slag contained 1 wt% U. SC&A also included the shielding 

effects of the wooden barrel on photon exposures, which were calculated at the barrel midsection. Beta doses were calculated above an uncovered barrel. 

To facilitate comparisons, Table 3-1 also includes approximate doses/exposures for 0.2 wt% U 

slag obtained by adjusting the SC&A calculations to the lower uranium concentration. Perusal 

of Table 3-1 shows that the photon doses from slag barrels as calculated by NIOSH are in good 

agreement with the slag adjusted values calculated by SC&A. The same is true for contact beta 

doses. Beta doses at 1 foot are significantly higher as calculated by NIOSH, resulting in doses 

that are more claimant favorable. While the methodologies used by both SC&A and NIOSH are 

comparable, as discussed above, we believe that a slag content of 1% U and a concentrate 

content of at least 5% are supported by the new information. 
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Table 3-1. MCNPX Calculations of External Dose from Barrels of Slag and Concentrate 

Photon Dose (mrem/hr) Beta Dose (mrem/hr) Source Component U content 

(wt%) @ 1 ft @ 1 m contact @ 1 ft 

NIOSH Slag 0.2 1.94E-03 5.78E-04 1.91E-01 4.62E-02 

Concentrate 2.0 1.65E-02 4.91E-03 1.93E+00 4.44E-01 

SC&A Slag 1.0 1.78E-02 3.59E-03 8.5E-01 7.0E-05 

Slag Adjusted* 0.2 3.56E-03 7.18E-04 1.7E-01 1.4E-05 

* 20% of value for 1% U 

3.5 REVIEW OF SECTION 5.3 “EXTERNAL DOSE FROM SURFACE 

CONTAMINATION” 

NIOSH developed photon and beta dose conversion factors for exposure from contaminated 

surfaces using MCNPX and summarized the results in Table 4 of the TBD. We note that the text 

discussing Table 4 always refers to dose rates, while the photon dose conversion factor is 

expressed in terms of exposure rate (mR/hr). 

Finding 6: NIOSH should review the units of measure for the photon dose conversion factors 

in Table 4 and determine if they are correct. If the units are correct, the text needs to be 

revised to discuss exposure rates rather than dose rates. 

The photon dose conversion factor from Table 4 is 6.79E-10 mR/hr per dpm/m2

 (or mrem/hr 

based on the discussion above). The photon dose rates were calculated at a distance of 1 ft from 

a 100-m diameter circle using MCNPX. Surface contamination was assumed to be 1 dpm/m2

alpha. Equilibrium with short-lived decay products was also assumed. The energy distribution 

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

comparison, we calculated the photon dose conversion factor for surface contamination using the 

version of Federal Guidance Report 13 available on CD, which used ICRP 60 (ICRP 1990) tissue 

weighting factors. The dose conversion factor based on equilibrium between U-238, Th-234, 

Pa-234m, and U-234 was 6.99E-10 mrem/hr per dpm/m2, a value in good agreement with the 

value in the Hooker TBD. 

To calculate the surface dose/exposure, NIOSH assumed that deposition occurred for 

2,400 hours, based on an air concentration of 43.1 dpm/m3

 and a terminal settling velocity of 

0.00075 m/s for 5 μm AMAD spherical particles resulting in a surface concentration of 

279,410 dpm/m2

. This general approach is reasonable, but the doses in Table 4 could be subject 

to adjustment based on resolution of several of the above findings.
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4.0 RECONCILIATION OF PRIOR SC&A FINDINGS 

SC&A’s findings based on its review of Appendix AA and the Hooker Petition Evaluation 

Report were discussed in detail at the ABRWH Uranium Refining Atomic Weapons Employers 

Work Group meeting on May 16, 2011 (Transcript 2011). NIOSH provided responses to the 

SC&A findings either verbally or via a white paper (Allen 2011a). The findings matrices 

presented in Tables 4-1 and 4-2 summarize the issues related to Appendix AA and to the Hooker 

Petition Evaluation Report and the actions on each finding taken by the Work Group. The Work 

Group determined that all of the findings had been resolved. However, as discussed in 

Section 3.2 above, review of NIOSH 2011b suggests that sufficient slag was available from 

ElectroMet to process about 42 tons per month at Hooker, rather than 10 tons per month as 

assumed by NIOSH. Consequently, SC&A believes that Finding 1 regarding Appendix AA and 

Finding B regarding the Petition Evaluation Report should be reopened based on the current 

review of NIOSH 2011b. SC&A also believes that Finding A of the ER should be reopened 

based on new information indicating that the input slag contained about 1% U. 

Table 4-1. Hooker Electrochemical Issues Matrix (TBD-6001 Appendix AA) 

Finding or 

Observation SC&A Reviewa NIOSH Initial Response Work Group Position Based 

on NIOSH Response 

Observation 1 NIOSH should clarify whether or 

not photofluorography was used 

at AWE sites. 

NIOSH added clarifying text to 

the TBDc stating that PA chest 

x-rays should be used 

(Transcriptb

 p. 21, line 16). 

The Work Group was satisfied 

with the NIOSH response. On a 

broader scale there was 

agreement that, unlike AEC sites, 

the default position for AWE sites 

should be x-rays rather than 

photofluorography, if there was 

no evidence to the contrary. 

Finding 1 NIOSH should re-examine the 

assumption that dumping of 

barrels could be done in 1 day per 

month. 

NIOSH included additional 

information in the TBD on the 

quantity of slag available within 

the AEC complex, supporting 

the assumption that processing 

of slag one day per month was 

reasonable. 

The Work Group determined that 

the finding was closed 

(Transcript p. 45, line 5). 

Finding 2 NIOSH should account for all 

activities causing inhalation 

exposure, not just those involved 

in dumping barrels of C-2 slag. 

The TBD includes airborne 

exposures from dumping drums 

of slag and filtering digester 

output. 

The Work Group determined that 

the finding was closed (Transcript 

p. 48, line 13). 

Finding 3 While SC&A does not agree with 

some of the underlying 

assumptions in their approach, the 

NIOSH approach appears to be 

bounding for dose reconstruction. 

However, our independent 

analyses indicate that the values 

for intake rate are unrealistically 

high. 

The methodology based on 

TBD-6001 was eliminated and 

was replaced in the TBD by slag 

handling data from 

Mallinckrodt, Fernald and 

Electromet. The inhalation 

exposure was based on the 95th

percentile of the slag handling 

data. 

The Work Group determined that 

the finding was closed (Transcript 

p. 52, line 5). 
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Table 4-1. Hooker Electrochemical Issues Matrix (TBD-6001 Appendix AA) 

Finding or 

Observation SC&A Reviewa

 NIOSH Initial Response Work Group Position Based 

on NIOSH Response 

Observation 2 If conversion of external exposure 

to a calendar-day basis is based on 

350 days per year, the basis for 

this assumption should be 

provided. In addition, NIOSH 

should provide example 

calculations to show how the 

values in Table 7.3 of TBD-6001 

were derived. 

There was a math error in 

Appendix AA, but this was 

eliminated with the new 

approach in the TBD. 

The Work Group was satisfied 

that the observation was 

adequately addressed (Transcript 

p. 52, line 19). 

Finding 4 NIOSH should correct the 

external exposure rates in Table 

AA.3. 

There was a math error in 

calculating external exposure 

rates, but the finding is not 

relevant since the TBD uses a 

revised approach. 

The Work Group determined that 

the finding was closed (Transcript 

p. 54, line 5). 

Finding 5 Rather than applying the values in 

Table 7.3 as default/ bounding 

values, NIOSH should derive the 

correct external dose values using 

MicroShield or MCNP. 

NIOSH used MCNPX to 

calculate external doses in the 

TBD. They noted that there was 

a calculational error in their 

MCNPX calculation that will 

require correction. On June 17, 

2011, NIOSH issued Revision 1 

to the TBD correcting the error. 

The Work Group determined that 

the finding was closed 

(Transcript p. 55, line 20). 

Observation 3 For consistency with the TBD6001 source document, the units 

in Table AA.4 should be specified 

as mrad or mrem/ calendar-day 

rather than mR/ calendar-day. 

Since TBD-6001 is no longer 

used, the observation is not 

relevant. 

The Work Group concurred that 

the issue was no longer relevant 

(Transcript p. 56, line 12). 

Finding 6 NIOSH should consider whether 

use of shallow dose estimates 

based on slag sampling is a more 

plausible approach than pro-rating 

exposures from a large uranium 

object. Alternatively, NIOSH 

could consider using a 

conservative estimate of the 

concentration of uranium in the 

barrel, and take into consideration 

self-shielding and the shielding 

from the barrel wall using 

MicroShield or MCNP. 

In the TBD, NIOSH used 

MCNPX to calculate shallow 

doses. NIOSH noted that was a 

spreadsheet error in the 

MCNPX calculations that 

required correction. On June 

17, 2011, NIOSH issued 

Revision 1 to the TBD 

correcting the error. 

The Work Group considered 

whether or not it was appropriate 

to close out a finding if an error 

needed to be corrected at some 

future time. It was agreed that the 

finding had been addressed (in 

this case use of MCNP) even 

though the exact value of the 

MCNP calculation remained to be 

corrected. The finding was 

closed (Transcript p. 65, line 21). 

Finding 7 NIOSH should provide an 

example calculation showing how 

they arrived at an inhalation 

intake of 1 pCi/calendar-day. 

The approach was revised in the 

TBD using 95th percentile 

values for measured airborne 

concentrations from surrogate 

facilities and 1 year of 

deposition. 

The Work Group concluded that 

the finding was adequately 

addressed (Transcript p. 66, line 

13). 
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Table 4-1. Hooker Electrochemical Issues Matrix (TBD-6001 Appendix AA) 

Finding or 

Observation SC&A Reviewa

 NIOSH Initial Response Work Group Position Based 

on NIOSH Response 

Finding 8 NIOSH should justify the use of a 

re-suspension factor of 1E-06/m. 

Since most of the airborne 

exposure is out-of-doors in 

conditions where contamination 

would be washed away, use of a 

re-suspension factor of 1E-06/m 

is appropriate. 

There was substantive discussion 

about whether use of 1E-06/m 

was appropriate for indoor 

exposures, but it was determined 

that indoor dust levels were more 

than an order of magnitude lower 

than those outdoors which would 

tend to offset a higher resuspension factor. In addition, no 

decay in the quantity of resuspended dust was assumed to 

occur over the residual period. 

The Work Group concluded that 

the finding was adequately 

addressed (Transcript p. 86, 

line 7). 

Broader questions regarding the 

general applicability of a resuspension factor of 1E-06 and 

other issues related to ORAUTOTIB-0070 (ORAUT 2008d

) are 

being considered by the 

Procedures Work Group. 

Finding 9 NIOSH should justify that the 

approach taken to calculate 

inhalation exposures during the 

residual period is bounding, and 

take into consideration SC&A’s 

review of ORAUT-OTIB-0070. 

The approach used to calculate 

internal exposures was revised 

for the TBD and the airborne 

concentration was assumed to 

remain constant during residual 

period. Consequently, SC&A’s 

critique of ORAUT-OTIB -0070 

was not relevant to Hooker. 

The Work Group concluded that 

the finding was adequately 

addressed (Transcript p. 86, line 

16). 

Finding 10 NIOSH needs to correct the 

calculation of external exposure 

during the residual period and 

revise the basis for converting this 

exposure to pCi/calendar-day. 

The calculational procedure for 

external exposure during the 

residual period was revised in 

the TBD. 

The Work Group concluded that 

the finding was adequately 

addressed (Transcript p. 86, line 

22). 

a – SC&A 2010. Review of the NIOSH Site Profile for the Hooker Electrochemical Company. Battelle-TBD-6001. 

Appendix AA. SCA-TR-SP2010-0034. September 2010. 

b – Transcript: ABRWH Uranium Refining Atomic Weapons Employers Work Group, May 16, 2011. 

c – TBD: Technical Basis Document for the Hooker Electrochemical Company, Niagara Falls New York. DCASTKBS-0009. Rev. 0. Effective Date: April 4, 2011 (NIOSH 2011a). 

d – ORAUT 2008. Dose Reconstruction during Residual Radioactivity Periods at Atomic Weapons Employer 

Facilities. ORAUT-OTIB-0070, Revision 00. Oak Ridge Associated Universities Team, Cincinnati, Ohio. 

March 10, 2008. 
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Table 4-2. Hooker Electrochemical Issues Matrix 

(Petition Evaluation Report for SEC-00141) 

Finding or 

Observation SC&A Reviewa NIOSH Initial Response Work Group Position Based 

on NIOSH Response 

Finding A NIOSH should re-examine its 

assumption that the slag 

contains 0.2% U; the 

assumption of 1% U is more 

favorable to claimants and, 

given the information 

presented here, it is bounding.

This issue was re-examined 

during preparation of the 

TBD and the available 

information suggests that the 

incoming slag concentration 

is 0.2%. 

The Work Group considered 

that this finding was adequately 

addressed (Transcript p. 94, 

line 4). 

Finding B NIOSH should review its 

estimate of the monthly slag 

throughput at Hooker to 

insure that all relevant data 

have been considered.

NIOSH included additional 

information in the TBD on 

the quantity of slag available 

within the AEC complex, 

supporting the assumption 

that processing of slag one 

day per month was 

reasonable. 

The Work Group considered 

that this finding was adequately 

addressed (Transcript p. 94, 

line 22). 

Finding C NIOSH should consider 

revising Appendix AA to base 

internal exposures on 

surrogate slag handling data, 

rather than on surrogate data 

from TBD-6001 scrap 

recovery operations. 

NIOSH revised the basis for 

internal exposures from using 

scrap handling data taken 

from TBD-6001 to using slag 

handling data at other AEC 

facilities. 

Since the revised approach 

used in the TBD also relied on 

surrogate data, the issue was 

raised as to whether SC&A had 

reviewed the use of surrogate 

data against the Board’s 

criteria. SC&A stated that they 

had not been tasked to conduct 

such a review. However, 

NIOSH was tasked with such a 

review at the previous Work 

Group meeting. Later in the 

meeting, NIOSH reviewed their 

analysis regarding the use of 

surrogate data.e

 At that time it 

was agreed that NIOSH should 

revise the surrogate data white 

paper to include details on 

airborne samples used in their 

analysis. SC&A would then 

review the white paper 

(Transcript pp. 166–170). 

Finding D NIOSH should clarify whether 

1.6 mrep/hr for gamma and 

11.5 mrep/hr for beta or the 

values contained in Tables 

AA.3 and AA.4 of Appendix 

AA should be used for a 

bounding calculation. 

The approach to bounding 

external exposures was 

changed in the TBD to use 

MCNP calculations rather 

than surrogate data. 

The Work Group considered 

that this finding was adequately 

addressed (Transcript p. 112, 

line 2). 
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Table 4-2. Hooker Electrochemical Issues Matrix 

(Petition Evaluation Report for SEC-00141) 

Finding or 

Observation SC&A Reviewa

 NIOSH Initial Response Work Group Position Based 

on NIOSH Response 

Finding E While clearly bounding, the 

measured gamma dose from 

the St. Louis Airport Site slag 

pile may not be representative 

of C-2 clag. 

St. Louis Airport Site data on 

C-2 slag were not used in the 

TBD. They were replaced 

with MCNP calculations. 

Both SC&A and NIOSH 

agreed that resolution of this 

finding was akin to that for 

Finding D. (Transcript p. 125, 

line 18.) Because of some 

confusion as to which finding 

was being discussed (E or F), 

the Work Group did not 

specifically take action on 

Finding E, but we recommend 

that the finding be closed. 

Although Finding E was not 

specifically addressed by the 

Work Group, it was later noted 

by the Chairman that all the 

issues had been closed out 

(Transcript p. 130, line 1). 

Finding F The PER should recognize 

that slag was present during 

the residual period, at least 

through 1958, and ensure that 

this information is 

incorporated into the 

bounding external exposure 

calculation for the residual 

period. 

NIOSH presented evidence 

that the documentation 

referring to slag remaining at 

Hooker during the residual 

period was actually referring 

to slag at the LOOW which 

was operated by Hooker.d 

The Work Group considered 

that this finding was adequately 

addressed (Transcript p. 124, 

line 12). 

Finding G Depending on employment 

history, use of a resuspension 

factor of 1E-06/m for the 

residual period may not be 

bounding when calculating 

inhalation doses. If NIOSH 

believes that use of this 

resuspension factor is 

appropriate, they should 

provide justification 

describing, for example, 

clean-up procedures 

conducted after the cessation 

of operations.

Since most of the airborne 

exposure is out-of-doors in 

conditions where 

contamination would be 

washed away, use of a 

resuspension factor of 1E06/m is appropriate. 

The Work Group considered 

that this finding was adequately 

addressed (Transcript p. 127, 

line 9). 
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Table 4-2. Hooker Electrochemical Issues Matrix 

(Petition Evaluation Report for SEC-00141) 

Finding or 

Observation SC&A Reviewa

 NIOSH Initial Response Work Group Position Based 

on NIOSH Response 

NOTICE:

Observation A NIOSH should explain why 

they accepted the petitioners’ 

assumptions regarding the 

duration of the operating 

period, since we are not 

aware of any evidence to 

support the extended 

operating period. 

This issue was discussed in 

the 2011 white paper by 

Allen (DCAS) where it was 

pointed out that operational 

exposures are calculated only 

for the period July 11, 1944, 

through January 15, 1946, 

although the covered period 

extends to December 31, 

1948. 

The Work Group was satisfied 

with NIOSH’s explanation as 

to the differences between the 

covered period and the 

operating period (Transcript p. 

129, line 13). 

a – SC&A 2011a. A Focused Review of The Hooker Electrochemical Company Petition Evaluation Report For 

SEC-0014. Contract No. 20002009-28555. SCA-SEC-2011-0018, Rev. 0. January 2011. 

b – Transcript: ABRWH Uranium Refining Atomic Weapons Employers Work Group, May 16, 2011. 

c – TBD: Technical Basis Document for the Hooker Electrochemical Company, Niagara Falls New York. DCASTKBS-0009. Rev. 0. Effective Date: April 4, 2011. 

d – White paper by D. Allen (DCAS). Observation A & Finding F, Hooker Electrochemical SEC Review, TBD6001 Working Group. April 2011. (Allen 2011a) 

e – White Paper by D. Allen (DCAS). Surrogate Data Evaluation – Hooker Electrochemical Company. April 

2011. (Allen 2011b)
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5.0 USE OF SURROGATE DATA 

Surrogate data was used in the Hooker TBD to estimate the airborne concentrations from 

handling C-2 slag. Contemporary data were collected from Fernald, MCW, and ElectroMet for 

these estimates. NIOSH reviewed this use of surrogate data in Allen 2011b and their conclusions 

are summarized below: 

The usage of surrogate data at Hooker Electrochemical is consistent with the 

criteria described in the Board’s document. Bounding, but plausible, estimates 

for internal exposure at Hooker Electrochemical can be prepared using the data 

collected from other facilities that performed a variety of similar uranium 

processing operations, and for which monitoring information is available. 

At its May 11, 2012, meeting, SC&A was requested by the Uranium Refining Atomic Weapons 

Employers Work Group to review the NIOSH White Paper (Allen 2011b) on the use of surrogate 

data in the Hooker TBD. Results of this review were documented in SC&A 2011b. SC&A 

concluded that: 

Based on our review, we believe that NIOSH has addressed the ABRWH 

surrogate data criteria in an appropriate manner, and that the use of surrogate 

data at Hooker is consistent with the Board criteria. Use of the selected 

surrogate data will result in plausible bounding estimates for internal exposures 

at Hooker.
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However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

6.0 SUMMARY 

Based on its review of the Hooker TBD (NIOSH 2011b), SC&A developed six findings as 

follows: 

Finding 1: NIOSH should review the assumptions regarding the composition of the incoming 

slag and the outgoing concentrate. 

Finding 2: NIOSH should re-examine its position that external exposures were based on slag 

input to the leaching process of 10 tons per month. It is possible that external exposures are 

understated by a factor of about 5. 

Finding 3: The basis for assuming that internal exposure from slag dust occurred 5% of the time 

needs to re-examined, as does the assumption that the concentrate contained only 2% U. It 

appears that this exposure time is understated by about a factor of 5 and the amount of uranium 

in the concentrate is understated by at least a factor of 2.5. 

Finding 4: NIOSH should review the ingestion intake to ensure that it is calculated in a manner 

consistent with calculation of the inhalation intake. 

Finding 5: NIOSH should confirm that the correct units of measure are cited in Tables 2 and 3. 

Finding 6: NIOSH should review the units of measure for the photon dose conversion factors in 

Table 4 and determine if they are correct. If the units are correct, the text needs to be revised to 

discuss exposure rates rather than dose rates. 

Findings 1, 2, and 3 are the result of new information uncovered during the course of this review. 
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REFERENCES 

Allen D., 2011a. NIOSH White Paper – Observation A and Finding F. Hooker Electrochemical 

SEC Review. TBD-6001 Working Group. April 2011. 

Allen D., 2011b. NIOSH White Paper - Surrogate Data Evaluation – Hooker Electrochemical 

Company. Hooker Electrochemical SEC Review.TBD-6001 Working Group. April 2011 – 

updated May 2011. 

Battelle 2006. Site Profiles for Atomic Weapons Employers that Refined Uranium and Thorium. 

Battelle-TBD-6001. Rev. F0. December 13, 2006. 

Battelle 2007. Site Profiles for Atomic Weapons Employers that Refined Uranium and Thorium 

– Appendix AA Hooker Electrochemical Company. Battelle-TBD-6001, Appendix AA. June 15, 

2007. 

Christofano, E., and W.B. Harris, 1960. “The Industrial Hygiene of Uranium Refining.” Env. 

Health 1(5):74-96. 

DOE 1977. Formerly Utilized MED/AEC Sites Remedial Action Program, Radiological Survey 

of the Hooker Chemical Company, Niagara Falls, New York, Final Report. U.S. Department of 

Energy, Washington, DC. Ref ID 10797. 

DOE 1985. Formerly Utilized Sites Remedial Action Report Elimination Report for Occidental 

Chemical Corporation (Former Hooker Electrochemical Company) Niagara Falls, New York, 

U.S. Department of Energy, Washington, DC. Ref ID 11002, p. 59. 

Dowling, F.A., c. 1944. Completion Report, Construction of Hooker Electrochemical Company 

P-45 Plant. Contract No. W-7405-ENG-28. Tonawanda Area-Manhattan District. SRDB Ref 

ID: 11002, pp. 102–112. 

Johnson, E.R., R.L. Doyle, J.R. Coleman, A.B. Kreuzmann, E.O. Rutenkroger, and W.H. 

Malotte 1954. Uranium Recovery from UF4 Reduction Bomb Wastes. AECD-3703. National 

Lead Company of Ohio. 

ICRP 1990. Recommendations of the International Commission on Radiological Protection, 

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

England. 

ICRP 1996. Conversion Coefficients for use in Radiological Protection against External Radiation, 

ICRP Publication 74, Annals of the ICRP, 26 (3/4). International Commission on Radiological 

Protection.

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. 
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However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

MED 1944. Medical Section – Manhattan District, Data Sheets for Industrial Hazard Rating. 

Manhattan Engineer District. SRDB Ref ID: 16323, pp. 29–30. 

NIOSH 2010. SEC Petition Evaluation Report, Petition SEC-00141: Hooker Electrochemical. 

May 3, 2010. 

NIOSH 2011a. Technical Basis Document for the Hooker Electrochemical Company, Rev. 0. 

DCAS-TKBS-0009. April 4, 2011. 

NIOSH 2011b. Technical Basis Document for Hooker Electrochemical Company, Rev. 1. 

DCAS-TKBS-0009. June 17, 2011. 

NYOO 1951. Production of Uranium Feed Materials. Manager of New York Operations Office 

(NYOO) and Director of Production. May 22, 1951. SRDB Ref ID: 4125. 

OCAS 2004. Technical Information Bulletin: Estimation Of Ingestion Intakes, Rev 0. OCASTIB-0009. Office of Compensation Analysis and Support, National Institute for Occupational 

Safety and Health, Cincinnati, Ohio. April 13, 2004. 

OCAS 2007. External Dose Reconstruction Implementation Guideline, OCAS-IG-001, Rev. 3. 

Office of Compensation Analysis and Support, National Institute for Occupational Safety and 

Health, Cincinnati, Ohio. November 21, 2007. 

ORAUT 2005. Basis For Development of an Exposure Matrix for the Mallinckrodt Chemical 

Company St. Louis Downtown Site and the St. Louis Airport Site, St. Louis, Missouri, Period of 

Operation: 1942–1958. ORAUT-TKBS-0005. Rev. 01. Oak Ridge Associated Universities 

Team, Cincinnati, Ohio. March 10, 2005. 

SC&A 2010. Review of the NIOSH Site Profile for the Hooker Electrochemical Company. 

Battelle-TBD-6001, Appendix AA. SCA-TR-SP2010-0034. SC&A, Inc., Vienna, Virginia. 

September 2010. 

SC&A 2011a. A Focused Review of the Hooker Electrochemical Company Petition Evaluation 

Report for SEC-00141. Contract No. 200-2009-28555. SCA-SEC-2011-0018, Rev. 0. SC&A, 

Inc., Vienna, Virginia. January 2011. 

SC&A 2011b. Review of NIOSH White Paper,“Surrogate Data Evaluation – 

Hooker Electrochemical Company.” Contract No. 200-2009-28555. SC&A, Inc., Vienna, 

Virginia. July 7, 2011. 

Spedding, F.H., H.A. Wilhelm, W.A. Keller 1945. The Production of Uranium by the Reduction 

of UF4 by Mg. CT-2712. Ames Laboratory, June 26, 1945. http://www.dtic.mil/cgibin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA322484. 

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

4337668. http://www.osti.gov/energycitations/servlets/purl/4337668/. 
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However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

NOTICE:

Transcript 2011. Uranium Refining Atomic Weapons Employers Work Group Meeting. May 

16, 2011. http://www.cdc.gov/niosh/ocas/pdfs/abrwh/2011/wgtr051611.pdf.
Effective Date: 

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Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

APPENDIX A: DUST SAMPLES USED BY SC&A TO CALCULATE INTERNAL 

EXPOSURES 

Table A-1. Airborne Dust Concentrations From Handling C-2 Slag 

Site Sample Description Air Conc. (dpm/m3) Reference 

Fernald 1639 BZ laborer using push broom to 

clean loose material from floor. 198 SRDB 42628, p. 13 

Fernald 1640 Ditto 232 SRDB 42628, p. 13 

Fernald 1641 Ditto 233 SRDB 42628, p. 13 

Fernald 1642 Ditto 490 SRDB 42628, p. 13 

Fernald 1643 Ditto 257 SRDB 42628, p. 13 

Fernald 1644 Ditto 346 SRDB 42628, p. 13 

Fernald 1645 Ditto 261 SRDB 42628, p. 13 

Fernald 1646 Ditto 200 SRDB 42628, p. 13 

Fernald 1647 Ditto 627 SRDB 42628, p. 13 

Fernald 1648 Ditto 336 SRDB 42628, p. 13 

Fernald 1649 Ditto 195 SRDB 42628, p. 13 

Fernald 1650 Ditto 338 SRDB 42628, p. 13 

Fernald 1105 

BZ laborer inside gondola with 

hatchet and shovel. Man cuts and 

shovels material from side of 

gondola and pitches onto pile on 

pad. 

15 SRDB 42628, p. 14 

Fernald 1106 Ditto 15 Ditto 

Fernald 1107 Ditto 30 Ditto 

Fernald 1108 Ditto 37 Ditto 

Fernald 1109 Ditto 97 Ditto 

Fernald 1110 Ditto 162 Ditto 

Fernald 1111 Ditto n.d. Ditto 

Fernald 1112 Ditto 69 Ditto 

Fernald 1113 Ditto 15 Ditto 

Fernald 1114 Ditto 47 Ditto 

Fernald 1115 Ditto 32 Ditto 

Fernald 1116 Ditto 83 Ditto 

Fernald 1117 Ditto 80 Ditto 

Fernald 1118 Ditto 68 Ditto 

Fernald 1119 Ditto 36 Ditto 

Fernald 1120 Ditto 135 Ditto 

Fernald 1121 Ditto 181 Ditto 

Fernald 1122 Ditto 32 Ditto 

Fernald 1123 Ditto 83 Ditto 

Fernald 1124 Ditto 64 Ditto 

Fernald 1125 Ditto 30 Ditto 

Fernald 1126 Ditto 23 Ditto 

Fernald 1127 Ditto 53 Ditto 

Fernald 1128 Ditto 79 Ditto 

Fernald 1129 Ditto 34 Ditto 

Fernald 1130 Ditto 45 Ditto 

Fernald 1131 

BZ hand shoveling airport scrap 

into 30-gal containers. No visible 

dust. 

106 SRDB 42628, p. 16 

Fernald 1132 Ditto 91 Ditto 

Fernald 1133 Ditto 75 Ditto 

Fernald 1134 Ditto 38 Ditto 
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Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

Table A-1. Airborne Dust Concentrations From Handling C-2 Slag 

Site Sample Description Air Conc. (dpm/m3) Reference 

Fernald 1135 Ditto n..d. Ditto 

Fernald 1136 Ditto 19 Ditto 

Fernald 1137 Ditto 95 Ditto 

Fernald 1138 Ditto 75 Ditto 

Fernald 1139 Ditto 49 Ditto 

Fernald 1140 Ditto 45 Ditto 

Fernald 1141 Ditto 30 Ditto 

Fernald 1142 Ditto 19 Ditto 

Fernald 3556 

BZ operator dumping drum of slag 

liner into outside crusher dumping 

station. 

110 SRDB 42628, p. 90 

Fernald 3472 Ditto 108 Ditto 

Fernald 3558 Ditto 61 Ditto 

Fernald 3557 Ditto 32 Ditto 

Fernald 4906 

BZ operator dumping 55-gal drum 

of MgF2 into leach tank, taking 

drum off and relidding drum. 

1125 SRDB 42628, p. 93 

Fernald 4907 Ditto 1674 Ditto 

Fernald 4908 Ditto 1533 Ditto 

Fernald 6993 BZ operator dumping drum of Cliner from 2nd floor drum dumper 793 SRDB 42627, p. 61 

Fernald 7509 Ditto 829 Ditto 

Fernald 7302 Ditto 424 Ditto 

Fernald 626 BZ dumping can of C-liner into 

dumping station. 247 SRDB 34544, p. 2 

Fernald 623 Ditto 191 Ditto 

Fernald 736 Ditto 255 Ditto 

Fernald T899 Ditto 206 Ditto 

Electromet III. 2 & 

6 Bomb Room, barrel slag and weigh 456 SRDB 8917, p. 7 

Electromet N/A Shovels slag into lean and rich 

drums 398 SRDB 8930, p. 19 

MCW Nov-53 Changing slag drums 107 SRDB 20675, pp. 19, 23 

MCW Nov-53 Ditto 7 Ditto 

MCW Apr-53 Ditto 81 Ditto 

MCW Oct-52 Ditto 27 Ditto 

MCW a BZ removing C-special drum 237 SRDB 9343, p. 19 

MCW b Ditto 60.8 Ditto 

Appendix A References 

Brealia [sic], A.J., 1949. Electro Metallurgical Co. Occupational Exposure to Radioactive Dust 

August 17–19, 1949. November 10, 1949. SRDB Ref ID: 8930. [A.J. Breslin, New York 

Operations Office, Atomic Energy Commission] 

Caplan, K.J., 1951. From K.J. Caplan (MCW) to Thayer (AEC), Subject: Results of Dust Study 

Six-E. February 26, 1951. SRDB Ref ID: 9343. 
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Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

NOTICE:

MCW no date: MCW Plant 6E, Occupational Exposure to Airborne Contaminants, MCW-18. 

References a study done November 18–20, 1953. Mallinckrodt Chemical Works, Industrial 

Hygiene Branch, Health and Safety. SRDB Ref ID: 20657. 

NLO 1956. Analytical Data Sheet Plant 8, BZ Results. Fernald. National Lead of Ohio. SRDB 

Ref ID: 34544. 

NLO 1958. Plant 8 Analytical Data Sheet, Air Dust, 1957–1970. Fernald. National Lead of 

Ohio. March 7 to October 13, 1958. SRDB Ref ID: 42627. 

NLO 1959. Plant 8 Analytical Data Sheet, Air Dust, 1957–1970. Fernald. National Lead of 

Ohio. February 6 to December 24, 1959. SRDB Ref ID: 42628. 

Various, 1947–1948, Reports on Dust Hazards at Electrometallurgical Company; various 

authors; dates from December 1947 through May 1948; SRDB Ref ID: 8917. 
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APPENDIX B: REPRODUCTION OF SLAG PLANT OPERATING INSTRUCTIONS 

 HOOKER ELECTROCHEMICAL COMPANY 

NI

 FORM-672 4.42 

AGARA FALLS, N.Y. 

 September 12, 1944 

OUTLINE FOR OPERATING C-2 SLAG PLANT 

 C-2 slag is a mixture of fine and coarse material. The operation is 

designed to concentrate the slag and reduce its bulk. There are two main parts in the operation: 

1. ACID TREATMENT The fines are dissolved in acid to remove lime. The filter 

cake from this reaction is one form of this product. 

2. SCREENING The rejects from screening the feed are barreled as a second form 

of product. 

PROCEDURE

 Charge two or three feet of water into an empty tank equipped with an agitator. 

 Add 50 barrels of lime as rapidly as possible. The coarse screen re-jects should be 

collected in wooden barrels. 

 Acid should be turned into the tank as soon as three barrels have been added. Slag 

should be added steadily and rapidly, so that the tank does not turn acid. 

 After the slag has been added, continue adding acid until the pH of the solution has 

dropped to 5. (It is necessary to take frequent tests toward the end of the reaction, since the pH of 

the solution will drop rapidly once the lime has been dissolved. If the pH drops lower than five, 

the metal agitator and pipe will chew out rapidly. 

 When the pH has dropped to 5, discontinue the acid addition and allow the tank to 

digest for 6 hours, testing the pH hourly. 

 When the six hour digestion period is complete, it is necessary to adjust the pH. THE 

SOLUTION MUST BE ALKALINE – pH 7 OR ABOVE, BEFORE FILTERING. Drop in one 

bag of lime; then test the pH. Add more lime if necessary to make the necessary adjustment. One bag of lime should usually suffice. 

 Next filter the batch, recycling to the same tank until the filtrate runs clear; then run 

the filtrate to D tank. 

 After the filtration is complete, wash the press for at least 12 hours. The wash water 

may be run to the sewer. 

 IT IS MOST IMPORTANT THAT ALL THE DISPOSAL ACID BE USED FOR C2 SLAG. Each hour that acid runs to the lime pit is wasted time for the slag plant. The 

work SHOULD be planned with this in mind. 

 The lumps should be rescreened if necessary to free them from fines. The barrels 

should be reheaded, weighed and stenciled with the net weight, name, (C-2 LUMPS) and lot 

number. The batch number should also be included. 

 The filer cake should be packed in metal drums, closed and stenciled with the name 

(C-2 CONC), net weight and lot number. 
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NOTICE:

 Before dumping the filtrate in C tank, a quart sample should be taken and given to the 

control chemist for testing. If O K, the batch may be dumped into the sewer. If not, see AVT for 

further instructions. 
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r for 

 

APPENDIX C: QUANTITY OF C-2 SLAG GENERATED PER TON OF URANIUM 

METAL PRODUCED 

A key question regarding the Hooker process was “how much slag was available for 

processing?” If one knows the amount of uranium produced at ElectroMet and the ratio of the 

mass of bomb liner to mass of uranium product, the mass of liner (or C-2 slag) can be estimated. 

Thayer (1955) cites a value of 0.432 lbs of liner per lb of UF4. Given the timeframe and the 

context of the discussion in that reference, the estimate refers to crushed MgF2 liners rather than 

dolomite which were used at ElectroMet. 

Spedding et al. (1945) provides the basis for estimating the quantity of fused dolomite used in 

the reduction bombs. A 10-in reduction bomb, described on p. 14 of that report, uses 168 lbs of 

UF4 in the charge. The bomb is 40 in long and has a 10.125-in inner diameter. A mandrel 

tapering from 9 in to 8.75 in is used to establish the annulus to be filled with dolomite (average 

annulus width – 0.625 in). The annulus volume is 746 in3

. Assuming that the density of fused 

dolomite is 0.104 lb/in3

 (2.88 g/cc) 

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

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

EwAA#v=onepage&q=fused%20dolomite&f=false), the mass of the liner is 92 lb5

 and the mass 

ratio of liner to UF4 is 0.54. As a check on this value, Section 5.4.4 of Spedding et al. 1945 

notes that the cost of liner is 8.65¢/lb U and the liner raw material cost is 13.5¢/lb of line

electrically-fused dolomite or 0.64 lbs of liner/lb U. Since 1.319 lbs of UF4 are required to 

produce 1 lb of U, the mass ratio of liner to UF4 is 0.49 – a value in reasonable agreement with 

the estimate based on the annulus volume. 

References 

Spedding, F.H., H.A. Wilhelm, and W.A. Keller 1945. The Production of Uranium by the 

Reduction of UF4 by Mg. CT-2712. Ames Laboratory, June 26, 1945. http://www.dtic.mil/cgibin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA322484 

Thayer 1955. Letter from Harold E. Thayer, MCW, to F. H. Belcher, USAEC, Capacity Slag 

Grinding Plant. May 13, 1955. SRDB 4012. 

5

 This assumes about 7 lbs of dolomite is at the top and at the bottom of the bomb.