Page 1 of 4 

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Fernald DWE Missed 

Intake (Plants 2/3)

Discussion Paper

 

National Institute for Occupational 

Safety and Health

July 30, 2018

Karen S. Kent 

Oak Ridge Associated Universities Team

Stuart L. Hinnefeld, Director 

Division of Compensation Analysis and Support
Discussion Paper Fernald DWE Missed Intake (Plants 2/3) July 27, 2018

Page 2 of 4 

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

ESTIMATION OF INTAKES TO URANIUM AND RADIUM-POOR RAFFINATES AT 

FERNALD

Summary

ORAUT-TKBS-0017-5, Feed Materials Production Center – Occupational Internal Dose

(ORAUT 2017), Section 5.3.5.2.3 describes how 230Th and other decay chain radionuclides are 

assigned to workers exposed to ore concentrates prior to the uranium being extracted from them 

in the refinery. The primary source of exposure for workers in Plants 2 and 3 occurred at the 

beginning of the processing operation – the ore and concentrate charging operations (i.e., the 

feed to the refinery digestors). Silo 3 materials are associated with the liquid stream contained in 

a closed piping system and then to a closed calcination system, which provides little exposure 

potential to the workers. For the period 1959 through 1961, these materials are assigned as 

described in ORAUT (2017). 

The average daily weighted exposure (DWE) air concentration values for the combined raffinate 

area of the refinery are the same from 1959-1961 (Wing 1961, p. 9; ORAUT 2018), as they are 

from 1965-1968 (Ross 1969, p. 10; ORAUT 2018). This is significant since the combined 

raffinate area of the refinery would be the location most likely to have raffinate exposure. 

Between 1959 and 1961, the refinery was running ore concentrates as feed, while from 1965 to 

1968, when the refinery restarted after being shut down for years; it was running scrap recovery 

as feed (Mead 1985; ORAUT 2018). The significance of running scrap recovery at refinery 

restart in fiscal year 1966 (Mead 1985; ORAUT 2018) is that the scrap is uranium that has 

previously been purified, so there are no decay chain radionuclides present. Since the airborne 

concentration of combined raffinate is the same for ore concentrates as it is for scrap recycle, 

there is no particular airborne exposure to 230Th or other decay chain nuclides in the ore 

concentrate raffinate.

Background 

The Refinery (Plants 2 and 3) consisted of three major process areas: digestion, extraction and 

denitration. Support areas included nitric acid recovery, raffinate treatment and refinery sump 

(Mead 1985, p. 34). The Refinery ran ore, Q-11 and Australian pitchblende, from 1954-1958 

(ORAUT 2017). The potential exposure to uranium and radium-poor raffinates occurred from 

1959-1961, when the refinery was running ore concentrates. The Q-11 ore contained all of the 

uranium daughter products, including 226Ra. When the ore was refined, 226Ra and other daughter 

products were concentrated in the waste stream, which was identified with the code “K-65.” 

Pitchblende ore processing resulted in “hot” raffinates, indicating that relatively high 

concentrations of 226Ra plus daughter products were in the waste stream. Silos 1 and 2 contained 

the K-65 “hot” raffinates and included concentrations of 226Ra. 

After 1958, when processing of the Q-11 and other pitchblende ores was completed, the source 

of the uranium for processing was yellowcake. The yellowcake had most of the radium and 

other impurities removed. This raffinate was called “cold raffinate” because the waste stream 
Discussion Paper Fernald DWE Missed Intake (Plants 2/3) July 27, 2018

Page 3 of 4 

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

had much lower concentrations of 226Ra plus daughters, compared to the K-65 raffinate. The 

cold raffinate was a calcined dry, dispersible powder that was transferred to Silo 3 using an 

enclosed airlift and was considered “radium-poor.” The raffinates were either a slurry or liquid, 

and were kept as a slurry until they were pumped to disposal pits. The front end of Plant 2 is 

where the materials were dumped into the digestor in the refinery and uranium was present, since 

it had not been refined out. 

Missed Intakes

It was assumed that workers were exposed to the ore concentrates as they were fed to the 

refinery, since the materials important in this process stream existed here. Because uranium was 

present, the potential exposure to uranium and radium-poor raffinates can be determined using 

the derived uranium intake based on bioassay, and including the non-uranium constituents from 

Silo 3, assuming that the 230Th is in equilibrium with the uranium, as described in ORAUT

(2017). Missed intake calculations for uranium based on urine bioassay from 1954-1958 were 

determined for absorption Type F, M and S (ORAUT 2018; IMBA files). The missed uranium 

intake calculations assumed a natural uranium enrichment and a minimum detectable activity 

(MDA) of 14 μg/L for urine. The urine sample was normalized assuming 1.4 L/day as the 

excretion rate. Missed intake calculations were estimated based on one-half of the MDA 

assuming that a urine sample was submitted on the last day of the intake period (i.e., December 

31, 1958). 

The ratios of the Silo 3 alpha constituents from Table 5-17 of ORAUT (2017) were summed with 

the uranium missed intake rates for the three absorption types. Actinium-227 was assumed to be 

in equilibrium with 227Th. Absorption Type F uranium and the Silo 3 constituents were the most 

restrictive of the three absorption types, as shown in the “Missed 1954-1958 Nat-U bioassay” tab 

of the “Fernald DWE & Missed Intake Plants 2-3, Rev. 01” Excel spreadsheet (ORAUT 2018). 

Therefore, absorption Type F uranium and Silo 3 constituents (i.e., Minimum Total Alpha 

Inhalation Intake Rate) were used for comparison to the total alpha intake with the DWE air 

sample concentration (ORAUT 2018). The derived Type F uranium intake was subtracted from 

the “Minimum Total Alpha Inhalation Intake Rate” to obtain the “Minimum Total Alpha Non-U 

Inhalation Intake Rate” or Silo 3 constituents. The 230Th amount was then subtracted to show the 

“Minimum Total Alpha Non-U Non-Th-230 Inhalation Intake Rate” amount.

Discussion

The “combined raffinate” total alpha DWE air sample concentrations from 1959-1961 were 0.1 

MAC (25.9 pCi/day) or 0.1 NCG (37 pCi/day), as shown in the “Plant 2-3 DWE” and “SRDB 

Review” tabs of ORAUT (2018). The “SRDB Review” tab of ORAUT (2018) shows other 

supporting references, which were reviewed. There is no reason to believe that the 0.1 MAC 

during ore concentrate was from 230Th. During the pitchblende ore-processing period, the ore 

radioactive components were based on uranium bioassay, and are higher than the 230Th based on 

air sampling of the combined raffinates beginning in 1959. 
Discussion Paper Fernald DWE Missed Intake (Plants 2/3) July 27, 2018

Page 4 of 4 

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

This approach is bounding since the total alpha intake based on uranium bioassay including the 

Silo 3 constituents, is well above what would be calculated based on the DWE values for 1959-

1961 from the “combined raffinate” in Plants 2 and 3. 

References

Mead, J., F. Savage, and R. Fugate, ca. 1985, History of the Operation of the Feed Materials 

Production Center by NLO, Inc., National Lead Company of Ohio, Cincinnati, Ohio. [SRDB 

Ref. ID: 26097] 

ORAUT (Oak Ridge Associated Universities Team), 2017, Feed Materials Production Center – 

Occupational Internal Dose, ORAUT-TKBS-0017-5, Rev. 03, Oak Ridge, Tennessee, 

March 30. [SRDB Ref ID: 166129] 

ORAUT (Oak Ridge Associated Universities Team), 2018, “Support files for Estimation of 

Intakes to Uranium and Radium-poor Raffinates at Fernald”, Oak Ridge, Tennessee, July 

23. [SRDB Ref ID: 172487] 

Ross, K. N., E. D. Leininger, and C. W. Zimber, 1969 “Exposure Study of Plant 2&3 Personnel 

to Airborne Radioactive Dust,” March 31, National Lead of Ohio, Cincinnati, Ohio. [SRDB 

Ref. ID: 41084] 

Wing, J. F., K. N. Ross, and G. E. Cline, 1961, Exposure Study of Plant 3 Personnel to Airborne 

Radioactive Dust, National Lead Company of Ohio, Health and Safety Division, Cincinnati, 

Ohio, December 11. [SRDB Ref. ID: 41111]