National Institute for Occupational Safety and Health

Response to SC&A’s “Focused Review of ORAUTRPRT-0092, Revision 00, and Remaining Petition 

SEC-00103 Evaluation Report Period: 1991–2007”

John Cardarelli II, PhD, CHP, CIH, PE

NIOSH, Research Health Physicist

Nancy Chalmers, PhD

ORAUT, Statistician

Advisory Board on Radiation and Worker Health

Savannah River Site Work Group Meeting

March 22, 2023
Overview

 Introduction

 NIOSH Responses to 5 SC&A Conclusions

 NIOSH Conclusion

3/22/2023 2
Introduction

 ORAUT-RPRT-0092, Evaluation of Bioassay Data for 

Subcontracted Construction Trade Workers at the 

Savannah River Site [ORAUT 2019]

– Original Purpose: use a Radiation Work Permit (RWP) 

sampling plan to determine whether subcontracted 

construction trade workers (subCTWs) were sufficiently 

monitored by bioassay such that their radiation doses 

could be reconstructed with sufficient accuracy

3/22/2023 4
Timeline of Pertinent Events

Onsite Execution of 

Sampling Plan

June

Technical Call, May 8

Draft Sampling Plan, April 17

Onsite Inventory, March

SC&A Memo on Draft, April 26 

Final Sampling

Plan Draft

May 16

ORAUT-RPRT-0092 Response 

Paper

SCA-TR-2019-

SEC005 SCA-TR-2020-

SEC006

Focused Review

SCA-TR-2022-

SEC001

2018 2019 2020 2021 2022

NIOSH/ORAUT SC&A

Data 

Received SEC Class Added

3/22/2023 5
Introduction – SC&A Conclusions

 SC&A Conclusions

1. Sampling premise is not sufficiently grounded in historical SRS 

practices.

2. Results for direct and effective monitoring may be overstated.

3. Generalized matching is not sufficient.

4. RWP-specified, job-specific bioassay data are incomplete.

5. Feasibility of co-exposure model needs to balance RWP 

implementation with completeness of coworker data.

 Focus has shifted from feasibility of dose reconstruction to 

feasibility of co-exposure modeling

3/22/2023 6
NIOSH Response to SC&A Conclusion 1

Sampling premise is not sufficiently grounded in historical SRS practices.
 

Monitoring Percentages 

 Based on SC&A Figure 1 and Table 2 (reproduced below) 

 Percent of Pu, Sr/FPs, Am, U, and Np bioassays required by RWP & number of 

RWPs 

Year % Pu # RWPs % Sr/FP # RWPs % Am # RWPs % U # RWPs % Np # RWPs 

1991 0% 16 0% 13 0% 4 25% 4 0% 1 

1992 0% 23 0% 9 0% 12 0% 20 0% 2 

1993 4% 27 0% 12 0% 13 9% 11 0% 11 

1994 78% 32 72% 25 33% 9 33% 15 NA 0 

1995 100% 15 100% 5 0% 2 100% 2 33% 3 

1996 100% 7 100% 3 0% 2 NA 0 100% 1 

1997 100% 9 100% 8 0% 1 NA 0 NA 0 

1998 80% 10 71% 7 0% 1 NA 0 NA 0 

3/22/2023 8
Radionuclides included on RWPs

 78% for Pu in 1994

– 78% of the 32 RWPs (or 25 RWPs) sampled from 1994 have 

Pu marked as required on the RWP

– remaining 22% (or 7 RWPs) are assumed to require Pu 

bioassay based on the work and/or area

 “Rise” from 0% (1991) to 78% (1994) to 100% (1995)

– Transition between procedure-driven bioassay program and 

RWP-driven bioassay program

– Check boxes on RWPs

• Early 1990s forms did not have them

• Middle and late 1990s forms have them

3/22/2023 9
Example of RWPs

RWP from 1992 RWP from 1997

3/15/2023 10
Uncertainty in Percentage Monitored

 “Rise” from 0% (1991) to 78% (1994) to 100% (1995)

 Purpose of the RWP sampling plan: Estimate the percentage 

of monitored subCTWs to within +/- 5% with 95% confidence

– Uncertainty in percentage of monitored subCTWs can be 

calculated

– Uncertainty in anything else can NOT be calculated, unless it 

was inventoried in March 2018

• Year was inventoried.

• Bioassay requirements were not.

 Uncertainties in SC&A Table 2 are unknowable

3/23/2023 11
Summary Response to SC&A Conclusion 1

 SC&A Conclusion 1: Sampling premise is not sufficiently 

grounded in historical SRS practices.

– Conclusion is based on a change from procedure-driven 

bioassay to RWP-driven bioassay

– Any conclusion drawn from comparing statistics with 

unknowable uncertainties is suspect

– Presence of bioassay requirements on all of the RWPs is 

not necessary for co-exposure modeling.

• Having RWPs is not even necessary

3/22/2023 12
NIOSH Response to SC&A Conclusion 2

Results for direct and effective monitoring may be overstated.
Inconsistency of the term “monitored”

 SC&A states, “NIOSH did not address all of the radionuclides

listed in the RWPs...” [SC&A 2022]

– Final draft sampling plan – “for all radionuclides listed on the

RWP other than tritium” [ORAUT 2018]

– ORAUT-RPRT-0092 [ORAUT 2019]

• Section 2.1 – “for all radionuclides listed on the RWP

other than tritium”

• Section 4.2 – “at least one required bioassay”

 SC&A is correct that the definition of “monitored” in ORAUTRPRT-0092 is not consistent.

– “All required nuclides” vs. “at least one required nuclide”

3/15/2023 14
Re-evaluated monitoring percentages by type

 Monitoring Types

– Direct monitoring

• subCTW was monitored

– Effective monitoring

• Either the worker was monitored or their coworker was

monitored

 NIOSH recalculated direct and effective monitoring percentages

where “monitored” means “all required nuclides”

3/22/2023 15
Purpose of Sampling Plan

 Purpose of the RWP sampling plan: Estimate the percentage

of monitored subCTWs to within +/- 5% with 95% confidence

– Uncertainty in percentage of monitored subCTWs can be

calculated

– Uncertainty in anything else can NOT be calculated, unless it

was inventoried in March 2018

• Year and area were inventoried.

3/22/2023 16
Results showed no significant difference

Monitoring Type and 

Definition

Weighted Point 

Estimate

95% Confidence 

Interval

Direct (at least one required 

nuclide)

95.13% (87.18%, 98.84%)

Direct (all required nuclides) 75.16% (68.15%, 81.32%)

Effective (at least one required 

nuclide)

97.52% (87.50%, 99.92%)

Effective (all required nuclides) 88.13% (80.14%, 93.74%)

 Direct intervals do not overlap, so direct percentage decreases with change

in definition.

 Effective intervals overlap, so change in definition does not have a

significant effect.

3/22/2023 17
Arbitrary monitoring threshold

 SC&A section 5.4 [SC&A 2022] suggests a monitoring threshold

– “SC&A’s selection of the compliance value less of [sic] than 80

percent was arbitrary, but it was a reasonable value below

which the rate of compliance certainly would be

questionable”

 Any suggested monitoring threshold would be completely

arbitrary.

 Every interval on the previous slide is above or contains the

arbitrary SC&A value of 80%.

3/22/2023 18
Alternatives to monitoring threshold

 RWP sampling plan focused on subCTWs.

 Must Account for Exposure Potential of Unmonitored Workers

– If unmonitored subCTWs represent a small fraction of the

highest exposed group, then a CX model can be developed.

– If 90% of subCTWs were unmonitored, but a large fraction of

highly-exposed workers within the entire population were

monitored, then a bounding CX model can be developed.

3/22/2023 19
Summary Response to SC&A Conclusion 2

 SC&A Conclusion 2: Results for direct and effective

monitoring may be overstated.

– NIOSH agrees that we did not address all radionuclides

when tallying results for ORAUT-RPRT-0092.

– Updated tallies are presented here.

– NIOSH conclusion has not changed: a co-exposure

model can still be constructed.

3/22/2023 20
NIOSH Response to SC&A Conclusion 3

Generalized matching is not sufficient.
What constitutes a coworker?

 For effective monitoring, what constitutes a coworker?

 Final draft sampling plan [ORAUT 2018]

– “co-worker on the same RWP”

– subCTW is implied since that was the sole focus

 ORAUT-RPRT-0092 [ORAUT 2019]

– subCTW on same RWP, same date, same time (within no

more than 15 minutes), any job title but “laborer” could be

used for another craft

 SC&A suggestion [SC&A 2022]

– subCTW on same RWP, same date, same time, same craft

3/22/2023 22
Coworker matching criteria too restrictive

 NIOSH believes the criteria for coworker matching (in ORAUTRPRT-0092 and SC&A suggestion) are more restrictive than 

necessary for developing co-exposure models.

 “Coworker” vs. “Co-Exposure” Misconception

– Discussed during 12/5/19 SRS and SEC Issues WG meeting 

[NIOSH 2019a]

– Discussed during 12/11/19 Advisory Board meeting [NIOSH 

2019b]

– Co-exposure models are based on workers with similar 

exposure potentials, not necessarily coworkers that worked 

right alongside them.

3/22/2023 23
Matching criteria for co-exposure models

 No requirement that the monitored person works closely with

unmonitored person

 Model is representative or bounding for unmonitored worker if

those monitored had the same or higher exposure potential

 Sampling plan focused on subCTWs, but if any monitored worker

(another subCTW, prime CTW, or nonCTW) with the same or

higher exposure potential was monitored, the model would be

representative or bounding

3/22/2023 24
Summary response to SC&A Conclusion 3

 SC&A Conclusion 3: Generalized matching is not sufficient.

– For co-exposure modeling, coworkers used for effective

monitoring matches need only have the same or higher

exposure potential.

– SC&A’s criteria of same RWP, same date, same time,

same craft are far too restrictive

3/22/2023 25
NIOSH Response to SC&A Conclusion 4

RWP-specified, job-specific bioassay data are incomplete.
Fraction of noncompliant monitoring

 Nearly half of conclusion 4 focuses on SC&A Figures 4 and 5

– The fraction on the y-axis is a noncompliance fraction.

Nuclides in left (right) plot had a perceived decrease (increase) in noncompliance between the time periods.

3/22/2023 27
Noncompliance uncertainties are unknown

 Uncertainties in noncompliance fractions are unknowable

– Year was inventoried. Nuclide was not.

 Comparison of point estimates without their uncertainties is

inappropriate.

 SC&A use of these phrases is inappropriate:

– “significantly higher”

– “statistically significant”

– “essentially the same”

 With uncertainty considered, the sets of bars on the previous

slide may not show any differences.

3/22/2023 28
Noncompliance does not prevent development

of co-exposure models

 Other half of conclusion 4 deals with job-specific sampling, audits,

a 1990 Tiger Team finding, and the 1997-1998 Westinghouse

Savannah River Company actions.

 ORAUT-RPRT-0102 states “compliance with the regulations in

place at the time the radiological work was performed is not

required in order to perform a dose reconstruction or develop a

co-exposure model” [ORAUT 2021]

 Dr. Paul Ziemer made a very similar statement during 4/15/21

Advisory Board meeting [NIOSH 2021]

 Audits, Tiger Team findings, and Company actions do not

necessarily prevent co-exposure modeling for SRS.

3/22/2023 29
“Job-specific” sample definition is confusing

 SRS 5Q1.1-506 (emphasis added):

– “Caution: It is EXTREMELY IMPORTANT to note that the effectiveness of the bioassay

program in general depends on combining both the routine program and the nonroutine, job-specific program. Any time unusual events occur, or jobs are performed

that may expose personnel to unusual hazards, a job-specific program should be

considered per Section 5.1.2.1.” [WSRC 1992, PDF p. 60]

– “Any time jobs are undertaken with the potential for unknown radiological conditions

to occur or unusual radionuclides to be present, a non-routine, job-specific bioassay

program should be considered. In such cases, an in-vitro sample and/or in-vivo count

may be required prior to commencing work and again at the conclusion of work. Such

a sampling program is at the discretion of HPO supervision and is noted on the

Radiological Work Permit for the task. Additional guidance on job-specific sampling

programs is available from the Dosimetry Evaluation Group at x5-2931.” [WSRC 1992,

PDF p. 57]

3/22/2023 30
“Job-specific” samples are not “special” samples

 Portions of 5Q1.1-506 seem to imply that job-specific samples 

are non-routine (or special) samples.

 This contradicts a 2017 interview with former site internal 

dosimetrist at SRS [ORAUT 2017]

– “Job-specific bioassay is a program prescribed in response to 

a specific event (the job) but is not a special bioassay”

3/22/2023 31
DOE changed Notice of Violation 

 Follow-up interview in August 2022 [ORAUT 2022a]

– Job-specific samples were part of the routine program and were not

special samples according to site practices, despite what the

procedures say.

– 1997 NOV was changed from Health and Safety violation to

Procedures violation, because DOE agreed that job-specific samples

were not special samples.

– Special bioassay samples

• Prescribed by RadCon prior to 1991

• Prescribed by internal dosimetrist starting in 1991 [ORAUT

2022b]

3/22/2023 32
Co-exposure models should include “special” samples

 A bounding co-exposure model can be constructed if a significant

portion of the most highly-exposed workers are part of the

dataset.

 If samples collected when there were suspected intakes of

radioactive material are part of the dataset, a bounding coexposure model could be constructed, regardless of job-specific

sampling and RWP work.

– Follow-up question in October 2022 [ORAUT 2022c]

• Requests for special samples triggered by events were

tracked by the internal dosimetrist in a computer

program called TRACK starting in 1991.

3/22/2023 33
Summary response to SC&A Conclusion 4

 Conclusion 4: RWP-specified, job-specific bioassay data are

incomplete.

– If the samples prescribed by the site internal dosimetrist

when a suspected intake occurred (samples in the TRACK

database) are part of NIOSH’s co-exposure database, this

is evidence that a bounding co-exposure model could be

constructed, despite SC&A Conclusion 4.

3/15/2023 34
NIOSH Response to SC&A Conclusion 5

Feasibility of co-exposure model needs to balance RWP implementation 

with completeness of coworker data.
Conclusion 5 Summary

 Email exchange [NIOSH/SC&A 2022]

– NIOSH

• “It appears this conclusion is a general statement that if

conclusions 1–4 are addressed, then SC&A ‘would

consider NIOSH’s conclusion valid...to support

development of a co-exposure model...’ ”

– SC&A

• the NIOSH interpretation is correct

 No detailed response necessary

3/22/2023 36
NIOSH Conclusions
Conclusions

 NIOSH addressed the five conclusions in the SC&A Focused 

Review and concludes:

1. Absence of bioassay requirements on RWPs in the early 1990s is 

irrelevant because bioassay programs were prescribed by procedure.

2. Changing the definition of “monitored” has the expected effect, but the 

new summary statistics do not prevent creating a co-exposure model.

3. SC&A’s coworker matching criteria are far too restrictive because for coexposure, the only necessary criterion is that the monitored worker has 

the same or higher exposure potential than the unmonitored worker.

4. Regardless of the issues SC&A pointed out, if the samples from the most 

highly-exposed workers (in the TRACK database) are part of the coexposure database, this is evidence that a co-exposure model could be 

constructed.

5. NIOSH has addressed the SC&A issues from the Focused Review and 

maintains that co-exposure models can be developed.

3/2/2023 38
References (1 of 3)

 NIOSH [2019a]. Centers for Disease Control National Institute for Occupational Safety and Health Advisory Board on Radiation 

and Worker Health Savannah River Site (SRS) and SEC Issues work groups joint meeting Thursday, December 5, 2019. Transcript. 

Washington, DC: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute 

for Occupational Safety and Health, Advisory Board on Radiation and Worker Health. [SRDB Ref ID: 182846]

 NIOSH [2019b]. Centers for Disease Control National Institute for Occupational Safety and Health Advisory Board on Radiation 

and Worker Health 132nd meeting Wednesday, December 11, 2019. Transcript. Washington, DC: U.S. Department of Health and 

Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Advisory 

Board on Radiation and Worker Health. [SRDB Ref ID: 184395]

 NIOSH [2020]. NIOSH/ORAU: NIOSH response to SC&A comments on ORAUT-RPRT-0092. Cincinnati, OH: U.S. Department of 

Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health.

August 18. [SRDB Ref ID: 182968]

 NIOSH [2021]. U.S. Department of Health and Human Services Centers for Disease Control National Institute for Occupational 

Safety and Health Advisory Board on Radiation and Worker Health 139th Meeting Thursday, April 15, 2021. Transcript. 

Washington, DC: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute 

for Occupational Safety and Health, Advisory Board on Radiation and Worker Health. [SRDB Ref ID: 187719]

 NIOSH [2022]. U.S. Department of Health and Human Services Centers for Disease Control National Institute for Occupational 

Safety and Health Advisory Board on Radiation and Worker Health 145th Meeting Thursday, April 28, 2022. Transcript. 

Washington, DC: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute 

for Occupational Safety and Health, Advisory Board on Radiation and Worker Health. [SRDB Ref ID: 193031]

3/22/2023 39
References (2 of 3)

 NIOSH/SC&A [2022]. Seeking clarification on conclusion 5 from the SC&A focused review of ORAUT-0092 2022. E-mail chain 

including NIOSH and SC&A. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control and 

Prevention, National Institute for Occupational Safety and Health. Arlington, VA: S. Cohen and Associates, Inc. May, June, 

October. [SRDB Ref ID: 194363]

 ORAUT [2017]. Documented communication with Tom LaBone on Savannah River Site. Oak Ridge, TN: Oak Ridge Associated 

Universities Team. October 6. [SRDB Ref ID: 168231]

 ORAUT [2018]. SRS work permit sampling plan. Oak Ridge, TN: Oak Ridge Associated Universities Team. May 16. [SRDB Ref ID: 

194480]

 ORAUT [2019]. Evaluation of bioassay data for subcontracted construction trade workers at SRS. Oak Ridge, TN: Oak Ridge 

Associated Universities Team. ORAUT-RPRT-0092 Rev. 00, June 14. [SRDB Ref ID: 176739]

 ORAUT [2021]. Assessment of Los Alamos National Laboratory plutonium bioassay programs 1996 to 2001. Oak Ridge, TN: Oak 

Ridge Associated Universities Team. ORAUT-RPRT-0102 Rev. 00, December 2. [SRDB Ref ID: 187245]

 ORAUT [2022a]. Documented communication – interview with Tom LaBone – follow-up question about SRS. Oak Ridge, TN: Oak 

Ridge Associated Universities Team. August 19. SRDB Ref ID: 193551

 ORAUT [2022b]. Documented communication with Dennis Hadlock on SRS procedure regarding who made the decision to put 

workers on special bioassay program. Oak Ridge, TN: Oak Ridge Associated Universities Team. August 15–16. [SRDB Ref ID: 

193470]

 ORAUT [2022c]. Documented communication – follow-up interview question with Tom LaBone about SRS 2022. Oak Ridge, TN: 

Oak Ridge Associated Universities Team. October 18. [SRDB Ref ID: 194367]

3/22/2023 40
References (3 of 3)

 SC&A [2018]. SC&A comments on NIOSH draft permit sampling plan. Memo to Savannah River Site Work Group. Arlington, VA: 

SC&A, Inc. April 26. [SRDB Ref ID: 176648]

 SC&A [2019]. Review of ORAUT-RPRT-0092, revision 00, “evaluation of bioassay data for subcontracted construction trade 

workers at the Savannah River Site” draft. Arlington, VA: SC&A, Inc. SCA-TR-2019-SEC005 Rev. 0, November 12. [SRDB Ref ID: 

179239]

 SC&A [2020]. Review of NIOSH response to SC&A on ORAUT-RPRT-0092, revision 00, on bioassay data for subcontracted 

construction trade workers at the Savannah River Site draft. Arlington, VA: SC&A, Inc. SCA-TR-2020-SEC006 Rev. 0, November 5. 

[SRDB Ref ID: 184019]

 SC&A [2022]. Focused review of ORAUT-RPRT-0092, revision 00, and remaining petition SEC-00103 evaluation report period: 

1991–2007 – draft. Arlington, VA: SC&A, Inc. SCA-TR-2022-SEC001 Rev. 0, April 22. [SRDB Ref ID: 192680]

 WSRC [1992]. Routine in vivo and in vitro bioassay scheduling and administration. Savannah River Site, Aiken, SC: Westinghouse 

Savannah River Company. WSRC-5Q1.1-506 Rev 3. [SRDB Ref ID: 152159]

3/22/2023 41
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TTY: 1-888-232-6348 www.cdc.gov

The findings and conclusions in this report are those of the authors and do not necessarily represent the 

official position of the Centers for Disease Control and Prevention.