ORAUT-OTIB-0070

Dose Reconstruction During Residual Radioactivity 

Periods at Atomic Weapons Employer Facilities

Report from the Procedures Review Subcommittee

Presented to the

ABRWH Full Board meeting

Augusta, Georgia 

March 12, 2013
ORAUT-OTIB-0070 Summary

• Provides guidance for 

– Estimating dose to workers at Atomic Weapons 

Employer (AWE) facilities when NIOSH determines 

“significant residual contamination” 

– Reconstruction of internal doses due to the 

resuspension of particulate surface contamination

• Only internal and external radiation exposures 

defined in 42 U.S.C. §7384n(c)(4) are included in 

residual period dose reconstructions; exposure 

from commercial sources is not used

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ORAUT-OTIB-0070 Timeline

• March 10, 2008 – Revision 0

• August 29, 2008 – SC&A Review (SCA-TR-TASK3-0009)

• July 14, 2010 – NIOSH Initial Responses

• July 26, 2010 – Discussed with Subcommittee 

• December 30, 2010 – SC&A Reply to NIOSH Responses

• January 5, 2012 – 2nd Discussion – Agreed on Approach

• March 5, 2012 – Revision 1

• July 31, 2012 – 3rd Discussion – Findings Resolved

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ORAUT-OTIB-0070, Revision 0

• Provides guidance for reconstruction of internal 

doses due to the resuspension of particulate 

surface contamination

• Recommends -

– 6 methods for estimating internal exposure to residual 

radioactivity at AWE facilities depending on:

• Type of data available (air sample or surface contamination)

• Timing of data (operational and/or post-operational)

– Resuspension factor of 1×10-6 m-1, based on numerous 

studies from 1964 to 2002

– Revision of 0.01 day-1 source term depletion rate to 

0.00067 in Rev 1, based on data from 4 AWE sites

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Findings Summary: OTIB-0070

• 15 Findings in total– complete histories captured in the Board Review System (BRS)

– http://app-cinc-dcas.cdc.gov:8106/documents/ 

default.aspx?mode=ASSIGNED 

– Resolution spanned 4+years

– 14 findings are Closed

– 1 is Addressed in TBD-6000 (also Closed)

• The following slides provide summary information on 

resolution of each Finding – Details in BRS and 

handout

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OTIB-0070 Review Findings

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# Finding Resolution

1 Inconsistent use of the 

resuspension factor (RF) –

The default source term 

depletion value of the 1% 

day-1 implies a RF of 8e-05 

per meter, which is nearly 2 

orders of magnitude higher 

than NIOSH’s recommended 

RF of 10-6 m-1. 

Closed on July 31, 2012 

OTIB-0070, Revision 1 changed the source term 

depletion rate from 1% day-1 to 0.00067 day-1, 

which is consistent with a RF of 10-6 m-1. 
OTIB-0070 Review Findings

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# Finding Resolution

2 OTIB-0070, Section 2.5 

references Sehmel 1980, Till 

and Meyer 1983, Linsley

1978, and Healy 1971. All of 

these references are (except 

Healy 1971) to outdoor soil 

contamination, which involve 

conditions with little 

resemblance to building 

surfaces, building uses, room 

heights, and ventilation rates.

Closed on July 31, 2012 

OTIB-0070, Revision 1 recalculated the default 

source-term depletion rate during the residual 

radiation periods based actual data from 4 

AWE sites (Blockson, Dow Madison, General 

Atomics, and Simonds Saw) rather than being 

based on literature sources where outdoor 

measurements were preponderant. 
OTIB-0070 Review Findings

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# Finding Resolution

3 Implicit in deriving the 

source term depletion rate 

(λ, Section 2.6) is that 

airborne contaminants are 

(1) uniformly distributed 

throughout the interior 

volume and (2) removed 

with 100% efficiency. 

Neither assumption is likely 

to exist. 

Closed on July 31, 2012 

OTIB-0070, Revision 1, Section 4.1 recalculated 

the default source-term depletion rate during the 

residual radiation periods based on averaging 

observed depletion rates at four AWE sites. 
OTIB-0070 Review Findings

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# Finding Resolution

4 Battelle-TBDs-6000/6001 

identified relatively large air 

concentrations during facility 

operations that were job 

specific. In contrast, OTIB0070, Attachment B identifies 

a single value for each of 3 

thorium sites that excludes 

process air sampling data.

Closed on January 5, 2011 

Air samples were selected to be indicative of 

general area conditions within the facilities at 

the start of the residual period and not 

potential exposure during the operational 

period. 
OTIB-0070 Review Findings

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# Finding Resolution

5 Attachment B cites survey 

data for 3 thorium facilities, 

but provides no further 

guidance on how these data 

sets are to be used. 

Both Closed on January 5, 2011 

Since it has never been used for DR purposes, 

Appendix B has been deemed unnecessary for 

the purpose of OTIB-0070, and has been 

removed from Revision 1. 6 Use of Horizons’ summary 

survey data as a default 

value for operational air 

concentration at a thorium 

refining facility is 

inappropriate and not 

claimant favorable.
OTIB-0070 Review Findings

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# Finding Resolution

7 It is unclear how the 

Attachment B Horizons 

geometric mean value of 

4.8 dpm/m3 was derived 

from the data contained in 

AEC 1955. 

Both Closed on January 5, 2011 

Since it has never been used for DR purposes, 

Appendix B has been deemed unnecessary for 

the purpose of OTIB-0070, and has been 

removed from Revision 1.

8 The derivation of Appendix 

B air concentration values 

(i.e., a GM of 1.2 dpm/m3

and a GSD of 3.9 dpm/m3) 

for Nuclear Metals from AEC 

1958 was not adequately 

explained.
OTIB-0070 Review Findings

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# Finding Resolution

9 The derivation of the 

Appendix B, Lindsey air 

concentrations values was 

not adequately explained 

and the values does not 

appear to correspond to 

those reported in the survey. 

Closed on July 31, 2012 

Since it has never been used for DR purposes, 

Appendix B has been deemed unnecessary for 

the purpose of OTIB-0070, and has been 

removed from Revision 1.

10 NIOSH’s recommended RF of 

10-6 m-1 is inappropriate. The 

scientific literature indicates

RF values of 10-4 to 10-3 m-1

for indoor activities involving

substantial industrial 

activities.

Closed on July 31, 2012 

A footnote added to Table 5-1 indicates that a 

site by site analysis should be conducted to 

establish the RF at sites where no postoperational clean-up has been performed, rather

than simply accepting an RF of 10-6 m-1.
OTIB-0070 Review Findings

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# Finding Resolution

11 Use of NUREG-1400 is 

inappropriate and 

technically not feasible since 

the total absence of data 

precludes a quantitative 

assignment to the source 

term that reflects residual 

contamination.

Closed on July 31, 2012 

Consideration of NUREG 1400 as a possible 

method for estimating residual contamination has 

been deleted from OTIB-0070, Revision 1 (see 

Table 5).
OTIB-0070 Review Findings

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# Finding Resolution

12 Use of Battelle-TBD-6000 for 

assigning operational air 

concentration values may 

not be claimant favorable.

This finding is being addressed in Battelle-TBD6000, Issue 4 – July 26, 2010

This finding will be closed when documentation 

from the TBD-6000 Work Group is received

indicating that TBD-6000, Issue 4 has been 

Closed.

13 It is not possible to judge 

whether the basic approach 

to developing inhalation 

doses in TBD-6001 is 

claimant favorable. 

Closed on July 31, 2012 

Since TBD-6001 has been cancelled, all references 

to and data from TBD-6001 have been removed 

from OTIB-0070, Revision 1.
OTIB-0070 Review Findings

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# Finding Resolution

14 Use of Battelle-TBD-6001 for 

determining inhalation 

doses may not be claimant 

favorable.

Closed on July 31, 2012 

Since TBD-6001 has been cancelled, all references 

to and data from TBD-6001 have been removed 

from OTIB-0070, Revision 1. 

15 Many of the assumptions 

that form the basis of the 

OCAS-TIB-009 ingestion 

model are too restrictive 

and may yield low ingestion 

estimates.

Closed on February 5, 2013

Since Finding TIB-009-01 has been resolved and 

Closed, Finding OTIB-0070-15 has also been 

Closed.
Questions?

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