SC&A PRESENTATION TO THE METALS AND 

CONTROLS WORK GROUP: SUMMARY OF 

SC&A’S “REVIEW OF SEC PETITION 

EVALUATION REPORT SEC-00236 

METALS AND CONTROLS CORPORATION”

MAY 3, 2018

Prepared by John Mauro, Rose Gogliotti, 

Robert Anigstein, & Nicole Briggs

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Metals and Controls Work Group

Josie Beach, Chairperson

Henry Anderson

David Kotelchuck

Loretta Valerio

2
Conclusions

1. SC&A concludes that doses to workers covered by the 

SEC petition can be reconstructed in a scientifically 

sound and claimant-favorable manner.

2. SC&A found errors and deficiencies in the scenarios, 

data, assumptions, and models described in the 

evaluation report (ER) for reconstructing doses, which 

will require revisions to the ER.

3
M&C Timeline of Key Activities and Events

4
Key SEC-Related Dates 2017/2018

5
Approach Used in SEC Petition Evaluation 

Report 00236 for Reconstructing Internal 

Exposures during the Residual Period

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Reconstructing Internal Exposures

1. During the residual period, although all fuel handling and 

assembly operations were completed, there remained surface 

contamination of uranium and thorium that could be resuspended 

and result in internal exposures.

2. In 1966 and 1967 (the last years of Atomic Weapons Employer 

[AWE] operations), a total of 7,765 swipe samples were collected 

in Building 10 (the building of primary interest). A subset of swipes 

was used to characterize the nature and extent of the gross alpha 

surface contamination.

3. NIOSH used these data in a conservative manner to derive the 

upper 95th percentile removable surface contamination of gross 

alpha activity, which was determined to be 54.8 dpm/100 cm2.

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Reconstructing Internal Exposures

4. Given a surface contamination level of 54.8 dpm/100 cm2, a 

resuspension factor (RF) of 1E-6/m was used to derive an 

airborne concentration of resuspended alpha emitters of 

0.00548 dpm/m3 (i.e., 54.8 dpm/100 cm2 × 1E-6/m × 1E4 cm2/m2

= 5.48E-3 dpm/m3) at the beginning of the residual period in 1968.

5. Considering that the gross alpha activity could be either uranium 

or thorium or both, NIOSH elected to assume the limiting 

radionuclide based on the organ of concern.

6. The residual activity declined at a rate of 0.000245/day based on 

the gross alpha survey data collected in 1982 and assuming that 

only 10% of the gross alpha activity observed was resuspendable. 

This is as compared to the default natural attenuation rate of 

0.00067/day used in ORAUT-OTIB-0070.

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Reconstructing Internal Exposures

7. Assuming an inhalation rate of 1.2 m3/hr, the inhalation rate 

as a function of time is used to convert intake rate to annual 

doses to the organs of concern using IMBA.

8. The rate of inadvertent ingestion was derived based on the 

default assumption that 1E-4 of the activity per m2 on 

surfaces was ingested per hour due to hand-to-mouth 

activities.

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SC&A Issues Associated with Internal Dose 

Reconstruction Protocols Described in the ER

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Issues Associated with the Specific Approach 

Used in the ER

 Observation 1: SC&A suggests that a more appropriate approach 

to deriving the chronic airborne concentration of uranium and 

thorium from resuspension during the residual period would be to 

use the mean value of the swipe data (i.e., 12.3 dpm/100 cm2, as 

opposed to the 95th percentile value of 54.8 dpm/100 cm2) and an 

RF of 1E-5/m, as opposed to 1-E6/m.

 Observation 2: The distinction between production and nonproduction workers should be better defined in the ER.

 Observation 3: NIOSH should consider adopting the approach 

used in the TBD and ER for Carborundum and General Steel 

Industries for deriving ingestion doses during the residual period.

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Issues Not Explicitly Addressed in the ER

Based on interviews with workers held October 24–October 26, 2017, 

SC&A found that many unique maintenance and repurposing activities 

were performed during the residual period by many workers who were 

not aware of any residual radioactivity. These activities could have 

resulted in internal exposures that are not addressed in the ER, 

including:

 Recurring subsurface maintenance and repurposing activities performed in 

contaminated soil, conduits, and pipelines beneath Building 10

 Periodic replacement of air filters potentially containing uranium and 

thorium

 Outdoor activities in the vicinity of the low-level radioactive waste burial 

grounds

 Ongoing treatment of wastewater that might have contained residues of 

uranium and thorium

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Approach Used in Petition Evaluation Report 

SEC-00236 for Reconstructing External 

Exposures during the Residual Period

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Reconstructing External Exposures

The ER uses the upper 95th percentile value of the 

external dosimetry data collected in the last year of AWE 

operations to serve as a surrogate to bound the external 

exposures experienced by workers during the residual 

period.

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Issues Associated with the Specific Approach 

Used in the ER

 Finding 2: NIOSH incorrectly transcribed some of the Landauer film 

badge dosimetry reports and incorrectly calculated annual 95th 

percentile external penetrating doses to workers in the residual 

period.

 Finding 3: NIOSH incorrectly calculated annual 95th percentile 

beta skin doses to workers in the residual period.

 Observation 4: Exposures experienced by High Flux Isotope 

Reactor (HFIR) workers cannot be used “as supporting evidence to 

validate the bounding method used in Section 7 of this report” as 

stated on page 24 of the ER.

 Observation 5: SC&A is concerned that it may be inappropriate to 

use external dosimetry data collected during the last year of AWE 

operations as the basis for bounding the external doses during the 

residual period.

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Issues Not Explicitly Addressed in the ER

Finding 1: Based on interviews with workers held October 24–

October 26, 2017, SC&A found that many unique maintenance and 

repurposing activities were performed during the residual period by 

many workers who were not aware of any residual radioactivity. These 

activities could have resulted in external exposures that are not 

addressed in the ER, including:

1. Recurring subsurface maintenance and repurposing activities in 

contaminated soil, conduits, and pipelines beneath Building 10

2. Outdoor activities in the vicinity of the low-level radioactive waste 

burial grounds

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Examples of How Internal Doses Associated 

with Maintenance and Repurposing Activities 

Could Be Addressed in the ER

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Assumptions for Modeling Subsurface 

Activities in Building 10

1. Assume workers spent 1 month per year involved in 

subsurface maintenance and refurbishing activities (based 

on interviews).

2. As a non-union shop, any person on site could have been 

assigned to perform subsurface activities in Building 10 

(based on interviews).

3. Activities included boring out clogged drain lines, excavating 

to a depth of 8 feet to repair, replace, and install conduits, 

pipelines, and new equipment (based on interviews).

4. Radionuclide concentration distributions in the pipelines and 

soil were similar to those observed during pre-D&D 

characterization activities performed in the 1990s (based on 

interviews).

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Assumptions for Modeling Subsurface 

Activities in Building 10

5. Create a distribution of radionuclide concentration in pipes in 

Building 10, assuming that the sample activity was 

representative of the full pipe length. Total uranium 

concentrations in the pipes in Building 10 ranged from 

9.75 pCi/g to 53,224.7 pCi/g. SC&A found the upper 95th 

percentile of total uranium in the pipes to be 5,878.1 pCi/g.

6. Airborne radionuclide concentrations assumed to be 

200 μg/m3. Higher values were possible but unlikely 

because the subsurface soil was chronically moist.

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Assumptions for Modeling Subsurface 

Activities in Building 10

7. Assuming an inhalation rate of 2.5 m3/hr for 184 hours per 

year, the uranium intake rate would be:

5,878.1 pCi/g × 2 × 10-4 g/m3 × 2.5 m3/h × 184 h/yr ×

0.037 Bq/pCi ≈ 20 Bq/yr)

8. This intake is associated with an effective dose commitment 

of:

20 Bq/yr × 9.4E-6 Sv/Bq × 1E5 mrem/Sv = 18 mrem/yr

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HVAC Maintenance

1. Specific activity of uranium dust (pCi/mg) on filters the same 

as in the air due to resuspension activities during the 

residual period

12.3 dpm/100 cm2 × 1E4 cm2/m2 × 1E-5/m ÷ 200 μg/m3 = 

6.15E-5 dpm/μg

2. Using a dust loading of 100 mg/m3 and 8 hours to perform a 

filter replacement activity, the intake of uranium would be:

6.15E-5 dpm/μg × 1,000 μg/mg × 100 mg/m3 × 1.2 m3/hr 

= 7.4 dpm/hr.

3. This intake rate is associated with doses on the order of 

1 mrem/yr (based on DCFs in FGR No.13).

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Questions?

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