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Weldon Spring Site 

SEC-00143 

Working group:

Michael H. Gibson-Chair

Richard A. Lemen, Ph.D., M.S.P.H.
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Brief Review of the Weldon 

Spring (WS) Site

• 1941-1946 Explosive production for Army

• 1946-1954 Idle

• 1954-1957 Land acquisition &

 plant development

• June 1957-12/31/1966 Uranium operations

• 12/31/1967 Plant transferred to DOD

• 1967-1969 DOD prepares plant, then terminates

• 1975-1985 Monitoring and Maintenance

• 1985-2002 WSSRAP- D&D of plant, quarry & pits. 

Material placed in engineered disposal cell.
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WS Site During Operations

(ORAUT-TKBS-0028-2, page 9)
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Engineered Disposal Cell 2008
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Recap of WS Site Profile and 

SEC Activities

• June 2005: NIOSH issued TKBS-0028-1 

 through 6

• March 2009: SC&A issued WS site profile 

 review

• Sept 2009: SEC-00143 qualified

• April 2010: NIOSH issued Evaluation Report 

 (ER) for SEC-00143.
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WS WG Meetings 

• 19 Oct 2010: WS 1st WG meeting

• 25 Jan 2011: WS 2nd WG meeting

• 9 May 2011: WS 3rd WG meeting

• 13 Sept 2011: WS 4th WG meeting

• 29 Nov 2011: WS 5th WG meeting by 

 phone conference.
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Summary of SEC Issues

for 1957-1967 

1. Accuracy and completeness of internal 

data (1a), external dose data (1c), air 

data (1b), and coworker data (1d).

2. Lack of egress monitoring.

3. Lack of dose records for 1967.

4. No radon/thoron measurements.
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SEC issues (continued)

5. Validity of method used to assign 

recycled uranium intakes.

6. Lack of neutron dose data.

7. Lack of air measurements at quarry and 

raffinate pits during 1957-1967.

8. Impact of accidents/incidents on dose 

reconstruction.

9. Geometry/extremity correction factors.
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Site Profile Issues

• There were 28 site profile issues identified.

• Most of these site profile issues have been 

incorporated into the SEC issues, or have 

been addressed, or are being addressed 

by changes in the WS TBD and PERs.

• SC&A is tracking the site profile issues 

along with the SEC issues.
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Closed SEC Issue

1a & 1c. Accuracy/completeness of data:

 Accuracy of data:

• Dose reconstructors use only photocopies of the 

original Weldon Spring data sheets.

• Electronic or CER databases are not used for 

dose reconstruction (DR).

 Completeness of data:

• Initial test of data completeness (15 workers) 

showed that 90-95% of the production workers 

were bioassayed and monitored for 1957-1967.
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Closed SEC Issue

1d. Coworker data:

• Sufficient data to create coworker bioassay 

and external database.

• Coworker data tables not needed to date.

• NIOSH will create coworker database if 

needed.

 Because of this information SEC Issues 1a, 1c, & 

1d have presently been closed.

[Note: SEC Issue 1b will be addressed later in this session]
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Closed SEC Issue

2. Lack of egress monitoring:

• Sufficient bioassay data to reconstruct 

dose if ingestion did occur.

• External exposures addressed by 

monitoring and skin dose calculations.

This issue has presently been closed.

 
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Closed SEC Issue

3. Lack of dose records for 1967:

• Indications are that 1967 may have been 

a transition year. Operational-period 

external and internal data sufficient to 

bound doses incurred during 1967.

This issue has presently been closed.

[Note: SEC Issue #4 will be addressed later in this session]
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Closed SEC Issue

5. Recycled uranium intakes:

• Method was addressed to determine if 

consistent and appropriate intakes were 

being applied during DR.

• It was found that inconsistencies in the 

DR process may have occurred.

• Changes in WS TBD and appropriate 

PER to be implemented.

This issue has presently been closed.
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Closed SEC Issue

6. Lack of neutron dose data:

• There is a lack of neutron dose data at 

Weldon Spring.

• Fernald neutron dose method can be 

used as surrogate because of similar 

materials, i.e., n/p values.

• SC&A independently verified NIOSH’s 

recommended n/p values.

This issue has presently been closed.
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Closed SEC Issue

7. Lack of air measurements at quarry 

and raffinate pits during 1957-1967:

• Measures performed in later period are 

applicable to operational period because 

quarry and pits not released to DOD and 

conditions remained fairly constant.

This issue has presently been closed.
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Closed SEC Issue

8. Impact of accidents/incidents on dose 

reconstruction: 

• Bioassay data available for workers with 

accidents in claims reviewed.

• Accidents/incidents are factored into DR 

process on an individual case basis.

This issue has presently been closed.
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Closed SEC Issue

9. Geometry and extremity monitoring:

• NIOSH evaluated methods used at other 

DOE uranium sites for dosimetry 

geometry and extremity monitoring and 

the impact on recorded doses at the 

Weldon Spring site.

• WS TBD will be revised to incorporate 

adjustments factors from DCAS-TIB-0013.

This issue has presently been closed.
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Status of Pending SEC Issues 

1b Air Data for Thorium intakes: 

• No thorium bioassay data (1966 chest 

counts not used).

• Gross-alpha activity air samples available.

• Assume 100% thorium activity.

• Original calculational and transcriptional 

error analyzed.

• These errors are called “blunders” in the 

scientific literature. They are not gross 

mistakes, but common errors).
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SEC Issue 1b Air Data (continued)

• Need to determine impact of errors on 

derived daily weighted average (DWA) air 

concentrations. 

• 9/07/2011: NIOSH issued white page 

addressing DWA errors. 

• 9/272011: SC&A issued response to 

NIOSH’s 9/07/2011 paper. SC&A 

recommended: 

DR implementation method be provided

The representativeness of the limited data be 

addressed.
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SEC Issue 1b Air Data (continued)

• 11/28/2011: NIOSH issued revised white 

page addressing DWA errors with DR 

implementation recommendations.

• 11/29/2011: DWA errors discussed at WS 

WG meeting of 11/29/2011.

• 11/29/2011: SC&A tasked with analyses of 

NIOSH’s revised DWE paper.
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Status of Pending SEC Issues 

4. No radon/thoron measurements:

• NIOSH performed analyses of potential 

environmental and indoor radon/thoron intakes 

and issued response on 4/21/2011.

• SC&A evaluated recommended model and found it 

to bound the potential intakes.

• The WS radon model is more conservative than 

previously proposed DOE site radon models in that 

it does not include any lost of radon/thoron through 

ventilation.

• WG recommends discussion with AB.
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Summary of WS SEC

• WS WG, NIOSH, and SC&A have been 

actively working on SEC (and site profile) 

issues during the last several years.

• Progress has been made for each of the 

nine SEC issues (and also the 28 site 

profile issues).

• Most SEC and Site Profile issues resolved 

except for AWE errors and use of 

radon/thoron model.