Potential Stable Metal Tritide Exposures

at the Mound Laboratory

by

Sam Chu, Bob Morris, Billy Smith, Mel Chew, and Leo Faust

Rev. 0

March 30, 2012

This is a working document prepared by NIOSH 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 Privacy Act 5 

USC §552a and has been cleared for distribution.
Rev. 0 Potential Stable Metal Tritide Exposures at the Mound Laboratory 03-30-12

This is a working document prepared by NIOSH 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 

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POTENTIAL STABLE METAL TRITIDE EXPOSURES

AT THE MOUND LABORATORY

EXECUTIVE SUMMARY

This report presents the bounding and best estimate internal dose associated with the intake of 

insoluble tritium particulate aerosols in the R/SW Tritium Complex (RSTC) at the Mound 

Laboratory. Of particular interest are personnel exposures to Type S insoluble stable metal 

tritides (SMTs) that could deliver more lung dose per unit intake than other more-soluble tritiated 

compounds. Large numbers of contamination swipe surveys taken on a daily basis from the 

operating areas during operations were located. The method for estimating the inhalation dose 

makes use of these contamination swipe data to estimate the SMT concentration resulting from 

the aerodynamic entrainment and/or mechanical resuspension of surface contamination. The 

accumulated dose was estimated for a Case Study that can typically be found in the dose 

reconstruction program. More than 69,000 swipe data entries for Rooms SW-150, SW-13, 

R-108, and SW-8 collectively were used in the assessment. The bounding and best estimate 

annual dose equivalents to the lung associated with intakes of the SMT are 0.48 mrem and 0.12

mrem, respectively. The assessment demonstrates that calculated exposures from the 

inhalation of insoluble metal tritides at Mound were small (in the millirem range), plausible, and 

bounding.

For the purposes of dose reconstruction, it is not necessary to determine “true” activity of SMT 

materials, due to beta energy self-absorption. In Section 2 of the Mound Technical Basis 

Document for Stable Tritiated Particles and Organically Bound Tritium (SRDB Ref ID 32921), it 

was demonstrated that apparent or “observed” activity on swipe samples is a better indicator of 

dose or dose potential than “true” activity. Moreover, it was demonstrated that knowledge of the 

specific SMT material and its size distribution are essentially unimportant to radiological 

protection. A simple radioassay for collected tritium is sufficient. For the purposes of this paper, 

it is necessary to determine the efficiency of the PC-5 proportional counter for counting SMTs. 
Rev. 0 Potential Stable Metal Tritide Exposures at the Mound Laboratory 03-30-12

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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 

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For the purpose of EEOICPA dose reconstruction, the observed activity from the PC-5 or LS 

represents the actual doses.

1.0 INTRODUCTION

Tritium research, development, analytical recovery, enrichment, and surveillance activities 

occurred in the SW/R Tritium Complex (SRTC) on the Mound Laboratory site. The SW/R 

Tritium Complex consisted of the Semi-Works (SW) Building and two rows of rooms in the 

adjacent Research (R) Building that were converted to tritium operations. SRTC tritium 

operations started in these rooms in the 1960s and continued beyond the 1980s. Workers 

could have handled and been exposed to special tritium compounds including metal tritides

while working in the SRTC. Mound had a comprehensive tritium urinalysis program, and 

workers with the potential for non-trivial exposure to SMTs participated in this program. In 

addition, Mound had a comprehensive air monitoring program designed to detect elemental 

tritium and/or tritiated water. In reality, SMTs are almost always accompanied by these more 

common forms of tritium, and this mitigates the potential for undetected releases of SMTs. 

Nonetheless, concern has been expressed regarding the adequacy of conventional tritium 

urinalysis and air monitoring methods for the detection of releases of insoluble SMTs. In the 

bounding case, if all tritium is in the form of insoluble (Type S) SMTs, a urinalysis program could 

fail to detect rather large intakes, which could result in correspondingly large missed doses,

particularly to the lung. This study reconstructs the potential exposures to SMTs for workers 

who had a theoretical potential for exposure to SMTs at Mound using an alternative method of 

more precisely bounding doses. 

The focus of this study is on Mound workers who had worked in the following four rooms in the

SRTC:

 SW-150, which housed the Gas Synthesis, High Pressure Gas Loading, Pinch Weld, Gas 

Tungsten Arc (GTA) Welding, and Component Functional Testing Systems
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 SW-13, which housed the Gas Synthesis System, the tritiated water synthesis and sampling 

system, and the Metallurgical Analysis Processes

 R-108, which housed and tritium recovery operations that included solid tritiated metal 

compounds, gas recovery, and purification from other tritium-handling processes

 SW-8, which housed the Effluent Removal System and was involved in tritium enrichment, 

recovery process technology, and the processing and containment of tritium-contaminated 

scrap from Mound activities as well as scrap generated at other DOE sites

For completeness, this study is expanded to address potential SMT exposures to workers 

during the decontamination and decommissioning (D&D) phase of the SW/R Tritium Complex.

2.0 METHODOLOGY

Dose estimates are determined via a dose reconstruction Case Study. The case in question 

specifies a worker who performed tritium operations in one of the SRTC rooms for two years 

and was first diagnosed with cancer 10 years after his/her last work environmental intake - a 

total span of 12 years from first intake to first cancer diagnosis. The dose estimates are based 

on the annual dose equivalents for the lung, which is the critical organ for the inhalation 

pathway. In order to maximize the estimated SMT exposures, the worker is assumed to have 

worked during the two years in which the air concentrations were the highest. 

The annual dose equivalents are calculated by using contamination surveillance (swipe) data to 

calculate the airborne concentrations of SMTs in the work areas, followed by using dose 

conversion factors (DCFs) derived from the Integrated Modules for Bioassay Analysis (IMBA) 

computer program to calculate annual dose equivalent (DE) to target organs from SMT intakes. 

The airborne contamination concentration is obtained by applying a resuspension factor defined 

as the ratio between the airborne concentration of a pollutant per cubic meter directly over a 

contaminated surface and the areal pollutant surface contamination. The concept of 

re-suspending surface contamination is conventionally used by the U.S. Department of Energy 
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or ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

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(DOE) and the U.S. Nuclear Regulatory Commission to perform safety analyses in the licensing 

of their facilities and operations. This method of dose estimation or consequence analysis is

bounding (the tritium on the swipe samples are assumed SMTs) and inherently conservative. 

Appendix A presents the detailed tritium swipe analysis, including discussions regarding the

swipe data search analysis, parameters, and assumptions that resulted in the annual dose 

equivalent to various organs.

3.0 CASE STUDY DOSE ANALYSIS

The calculation of the SMT exposures for the Case Study is represented by Equation (1):

 ∑∑ 

 

 

 

 

 

Where:

DE = Accumulated dose equivalent (mrem)

AD = Annual dose from an intake

m = Number of years of intake

n = Number of years from first intake to the year cancer was diagnosed

j = Number of years of annual doses from a single intake

k = Year of intake

i = Integer series in increments of 1 from 0 to n. 

Expanding for the Case Study (n = 12 years, m = 2 years) results in Equation (2):

 ∑ 

 

 

 ∑  

 

 
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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 

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Substituting the annual dose equivalents to the lung in Appendix A to Equation (2) yields the 

maximum potential SMT dose to the workers who worked in the SRTC during the period from 

1968 through 1989. The maximum potential SMT doses are presented in Table 1.

Table 1: Maximum Potential SMT Doses to the Lung (mrem)

Room

Best Est. (50th percentile) Swipe Values Bounding (95th percentile) Swipe Values

∑ 

 

 

∑ 

 

 

Total ∑ 

 

 

∑ 

 

 

Total

SW-150 0.04 0.04 0.08 0.16 0.15 0.31

SW-13 0.04 0.03 0.07 0.12 0.11 0.23

R-108 0.02 0.01 0.03 0.10 0.07 0.17

SW-8 0.02 0.11 0.12 0.30 0.19 0.48

Note: The respective two years with the highest air concentrations associated with the specified rooms are:

95th percentile 50th percentile

Year 1 Year 2 Year 1 Year 2

SW-150 1968 1977 1968 1977

SW-13 1975 1974 1974 1975

R-108 1985 1984 1985 1989

SW-8 1977 1975 1986 1969

4.0 RESULTS DISCUSSION

Table 1 lists the resulting bounding and the best estimate SMT lung doses for the Case Study 

scenario for all the SRTC rooms of interest. The highest bounding and best estimate DE values 

in Table 1 are 0.48 mrem and 0.12 mrem to the lung, respectively. These DE values are those 

that the Mound tritium workers could potentially have received by working in the SRTC. It can 

be concluded that the exposures from the inhalation of Type S insoluble metal tritides at Mound 

are below the plausible mrem levels range.
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5.0 DECONTAMINATION AND DECOMMISSIONING PHASE

Interviews from three health physics professionals who worked at Mound have provided insight 

into the tritium (T2, HT, HTO and OBT) and SMT monitoring programs that were in effect at 

Mound during various phases of plant remodeling and D&D activities. A summary of the salient

points made in their interviews are presented below. In this overview, the facilities of primary

concern are the SW and R buildings where SMTs were developed or used. Interviewees are 

identified in this document by the initial of their last name.

Work performed on the insoluble SMT compounds was performed inside glove boxes equipped 

with HEPA filters so the likelihood of these particulates entering the facilities’ ductwork was 

extremely low. Tritiated particulates found inside the ductwork were most likely associated with

hydrated iron oxides (rust) that could have formed from a reaction of HTO on the iron/stainless 

steel in the ductwork. Any tritium in this water of hydration would act as HTO after intake. In 

addition, upon completion of the insoluble tritide campaign, the laboratory workers who had 

worked with these materials completely cleaned up the laboratories, hoods, and glove boxes 

prior the beginning of any facility D&D being performed. As a result of this clean-up, the 

exposure potential of D&D workers to these compounds was very low.

Insoluble SMTs at Mound were a small fraction of the total tritium handled or processed through 

the plant, and protective measure implemented for its monitoring were accounted for by the 

protections for HTO and OBT. Although the insoluble SMT particles contain quantities of tritium,

the chemistry and biokinetics of the SMTs did not represent a significant exposure hazard,

primarily due to the low energy of the tritium betas and their self-absorption within the particles 

themselves. These particles, because of their insolubility, would not produce a whole body 

exposure like HTO or OBT. Insoluble SMT particles could have exposed the lungs, but not to 

the level predicted by the amount of tritium in the volume of the particles. Only exposures from 

the beta rays leaving the surface of the particles could expose the lung or other organs. 
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The workplace monitoring concentrated on personnel protective measures against the most 

likely tritium compound hazards in the Mound workplaces. Health Physics procedures and 

practices implemented at the plant were uniform and strictly enforced in assessing the 

workplace hazards prior to the initiation of either facility modifications or D&D activities.

Interview Summaries:

The first person interviewed, Mr. XX, worked at Mound from 1981 to 2005. In previous 

interviews with Mr. XX, we interpreted him to say that “all workers that were involved in the 

ductwork removal between the B, R and SW buildings to the SW stack were bioassayed for 

tritium.” Clarification from Mr. XX indicated that our interpretation was in error. He indicated 

that D&D workers came from two populations of workers, PP Building workers and SW Building 

workers. Only SW workers were on a routine tritium bioassay program; PP workers were not. 

He indicated that this mix of workers applied the normal end-of-job sampling protocols they 

used. Although they all wore dust respirators, only the PP workers left nose swipes because

that was their procedure after wearing a respirator in the plutonium areas; SW workers did not 

leave nose swipes because the respirators were for dust protection only. The PP workers did 

not leave bioassay samples for tritium because the “ducts were from the cold side of SW and 

therefore no need.” Although Mr. XX suspected the ducts were clean, he confirmed that the 

reason he had directed that the ductwork be swiped for alpha was his recent experience in PP 

Building D&D. He knew that some alpha emitters had been used in SW Building; to confirm that 

this run of ductwork had not come from those areas he had swipes taken and counted for alpha. 

No alpha activity was found. These swipes were not counted for tritium. This work preceded by 

about 10 years concerns about D&D removal of SW building ductwork and the issues of stable 

metal tritides.

Mr. XX was not at Mound during the D&D phase of the SW Building ductwork project. He 

suggests that Mr. XY, who was involved with the tritium areas in the R, SW and T buildings,

would know the workplace indicators surrounding this project. The plant established a 

methodology to quantify the radiological hazards associated with insoluble SMT by using 
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scanning electron microscopy (SEM) techniques and stoichiometrically calculating the amount 

of tritium in the number and size of particles collected on breathing zone (BZ) air samplers worn 

by workers. 

The second person interviewed, Mr. XY, worked at Mound from 1990 to 2003. Mr. XY indicated 

that full-blown D&D of SW and R buildings, excluding Corridor 5, did not get started until 1998 

or 1999. With the implementation of DAC-hr tracking, based on the use of BZ sample results 

collected from workers, the plant did begin regularly monitoring for insoluble particulate tritides. 

All of these D&D workers wore BZ samplers and this change occurred around 1999. The 

assumption used to monitor workers was that the urine samples analyzed for betas represented 

the soluble tritium from tritium gas and/or HTO, and the particulates collected by the BZ 

samplers represented the insoluble particles and tritium betas that would not have shown up in 

the urine samples. The BZ filters would have been counted via liquid scintillation (LS) and/or 

proportional counters. There was a Technical Basis Document (TBD) developed describing the 

methods used for this analysis.

The third person interviewed, Mr. XZ, worked at Mound from 1997 through 2003. Mr. XZ was 

involved in the implementation of the programs and practices, and the development of the 

Radiation Work Permits (RWPs), that were in place to monitor and protect workers during the 

D&D of these areas. Some of the specific work controls and work place monitoring indicators 

included the swiping of all ductwork. Any area with the potential for contamination (tritium, 

alpha, or beta) was required to be characterized. A Needs Evaluation was required prior to 

entry or demolition to assess the level of worker protections required, the need to wear

breathing zone samplers to collect particulates, and the need for bioassay sampling and 

analyses for intake determinations.

BZ samples were examined via SEM techniques and LS counted for tritium. Mr. XZ indicated 

that, based on this sampling and analysis protocol, the insoluble stable metal tritides were not a 

significant exposure hazard, and they were less of a hazard compared to the soluble forms 

(HTO and OBT) that would show up in urinalysis. The radiological controls for an area/job were 
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driven by the soluble tritium forms (HTO & OBT), not the insoluble SMT. He mentioned that,

generally, high-contamination areas (HCAs) were the only areas likely to exceed 2% of a DAC 

and require personal monitoring for tritium. Mr. XZ felt that it would be rare to have a situation 

where a job would run into an unexpected HCA and not already have some form of air 

monitoring in place to estimate the insoluble SMT exposure. He did not recall any incidents 

where it was determined after the fact that a worker should have been monitored for insoluble 

SMTs and was not. It was Mr. XZ’s recollection that the D&D of the main tritium areas did not 

occur until the insoluble SMT monitoring program was in place. The D&D health physics 

program was aware of the fact that insoluble SMTs were produced during operations and the 

protective measures and monitoring techniques used at the plant during this phase of Mound’s 

history provided adequate protection and monitoring for these potential hazards. In addition, 

Mr. XZ felt that the protective measures for HTO used at the plant during the previous phases of 

Mound’s history also provided adequate protection to mitigate exposures from insoluble SMTs.

Conclusion

The worker protection practices and health physics program used at Mound for protection 

against insoluble tritides, and the processes in which they were encountered, indicates that the 

SMTs did not present any internal dose to workers, theoretically and physically.

6.0 REFERENCES

Chu, S., Excel Spreadsheet, R-108 SW-8 in 1980s 3-12 [location to be determined]

Chu, S., Excel Spreadsheet, R-108 SW-8 pre 1980 3-12 [location to be determined]

Chu, S., Excel Spreadsheet, SW-13 SW-150 1960s-1990s [location to be determined]
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APPENDIX A: ANNUAL ORGAN DOSE EQUIVALENT CALCULATIONS

A 1.0 Analytical Model

During the SW/R Tritium Complex (SRTC) operational period, routine smear samples were 

taken in each room and counted to ensure that surface contamination levels were within the 

limits set by the Radiological Control Program at that time. The routine facility contamination 

surveillance (swipe) data on record were used to calculate airborne SMT concentration by 

applying a resuspension factor (RF) that enables estimation of the amount of removable surface 

contamination that had become airborne due to the aerodynamic entrainment and mechanical 

actions or disturbances. The RF is defined as the ratio between the airborne concentration of a 

pollutant per cubic meter directly over a contaminated surface and the areal pollutant surface 

contamination; the RF has a unit of m-1. In concept, the factor represents the uniform 

concentration above a contaminated surface at a certain height. The factors are derived from 

resuspension rate experiments and field studies in which the airborne concentration of a 

pollutant was measured at a specified height above the surface collected over a specified period 

versus the level of surface contamination.

Next, dose conversion factors (DCFs) derived from the Integrated Modules for Bioassay 

Analysis (IMBA) computer program were used to calculate the annual dose equivalent (DE) to 

target organs from SMT intakes. The DEs are estimated to provide 50 subsequent annual 

doses from the total intake in the year specified for the Case Study dose reconstruction used in 

this analysis.
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The calculation model is represented by Equation (A-1):

 {[( ( 

)

 

) ] } (A-1)

Where:

DE = Internal organ dose (mrem)

CPC-5 = Contamination swipe data as counted by a PC-5 proportional counter

 (cpm/100 cm2)

EffPC-5 = Counter efficiency (cpm/dpm)

CF = Conversion Factor of 4.505 × 10-7μCi/dpm

100 = Constant that converts 100 cm2to m2

RF = Resuspension Factor defined as the ratio between the airborne concentration of a 

 pollutant per cubic meter directly over a contaminated surface and the areal 

 pollutant surface contamination (unit = m

-1

)

Br = Worker’s breathing rate of 1.2 m3/hr (ICRP 1994a)

T = Exposure time of 2,000 working hr/yr

DCF = Dose Conversion Factor for Type S, 5-μm activity median aerodynamic diameter 

 (AMAD) SMT for the target organ mrem/μCi 

Exposures to SMT are estimated on a monthly or annual basis using the 50th and 95th percentile 

SMT air concentrations derived from the contamination swipe data. The surface contamination 

represented by the swipe samples is assumed to consist entirely of insoluble SMT particulates. 

Nine target organs projected to receive the highest total doses over an extended period (50 

years) are evaluated for the inhalation of Type S SMT particulates. 
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A 2.0 Contamination Survey Data and Analysis

The routine contamination swipe data used in this report are obtained from a set of Building 

Contamination Surveys (Wipe Samples) Reports for the R and SW Buildings. More than 10,900

SRDB documents were reviewed and more than 220,000 pages were read. Twenty-nine (29) of 

those reports contained swipe data reported on a routine basis for Rooms SW-150, SW-13, 

R-108, and SW-8 for the period between 1968 and 1989. Typical locations in the rooms where 

swipe samples were taken are shown in Figures A-1 through A-4. In general, when the swipe 

data were reported, only the high, low and average values were reported, as shown in Figure 

A-5. The high values are used to generate the data statistics except for data taken in Rooms 

R-108 and SW-8 from the 1970s up to 1984. For these rooms and this time period, each high, 

low and average datum was considered a distinct data point for use to generate the data 

statistics. Figure A-6 shows the yearly swipe sample populations of the four rooms in the 22-

year period. A total of >69,000 swipe data values were used for all four rooms. Although swipe 

data are available for a varying number of months (e.g., from 5 to 12 per year), typically there is 

a sufficiently large number of samples to develop the 95th-percentile contamination values on a 

monthly basis. Data for several months are combined to increase the data population to more 

than ten, when necessary. The airborne SMT concentrations in the rooms were calculated 

based on the median and 95th-percentile values.
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NOTE: Swipe locations related to the measurements denoted by the 

uncircled values with units of cm.

Figure A-1: Typical Contamination Swipe Locations Denoted by the 

Measurements in Room SW-150
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Figure A-2: Typical Contamination Swipe Locations Denoted by the 

Measurements in Room SW-13
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Figure A-3: Typical Contamination Swipe Locations Denoted by the 

Measurements in Room R-108
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Figure A-4: Typical Contamination Swipe Locations Denoted by 

the Measurements in Room SW-8
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Figure A-5: Typical High, Low and Average Swipe Values Reported 

on the Health Physics Trend Sheets
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Figure A-6: Available Swipe Sample Populations

The 95th-percentile contamination values are developed by: plotting the “z scores” of the 

data on the x axis and the natural logs of the data on the y axis; and (2) using the plotted data to 

determine a linear equation and the associated fit parameter, R2. The linear equation will be in 

the form of Equation A-2: 

 (A-2)

Where:

y = Natural log of the data

m = Slope of the line

x = Z-score

b = Y-intercept

10

100

1000

10000

1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989

Swipe Data Population

SW-150

SW-13

SW-8

R-108
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For a true lognormal distribution, the geometric mean (GM), which is also the 50th percentile, is 

equal to (eb); the geometric standard deviation (GSD) is equal to (em); and the 95th percentile is 

equal to [GM × (GSD)1.645]. Figures A-7 and A-8 show the resulting 95th- and 50th- percentile 

swipe values for the rooms that were used to calculate the airborne contamination.

Figure A-7: 95th Percentile Monthly Swipe Sample Counts

0

5000

10000

15000

20000

25000

1968196919701971197219731974197519761977197819791980198119821983198419851986198719881989

95%tile Swipe Data (cpm/100cm2) 

SW-150

SW-13

SW-8

R-108
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Figure A-8: 50th Percentile Monthly Swipe Sample Counts

Table A-1 identifies the respective two years with the highest swipe sample values for the 

specified SRTC rooms based on the 95th- and 50th- percentile swipe data values.

Table A-1: Two Years with the Highest Swipe Sample Values by SRTC Room

Room 50th Percentile 95th Percentile

SW-150 1968

1977

1968

1977

SW-13 1974

1975

1974

1975

SW-8

1969

1986

1975

1977

R-108 1985

1989

1985

1984

0

1000

2000

3000

4000

5000

6000

7000

1968196919701971197219731974197519761977197819791980198119821983198419851986198719881989

50%tile Swipe Data (cpm/100cm2) 

SW-150

SW-13

SW-8

R-108
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A 3.0 PC-5 Efficiency (EFFPC-5) and Self Absorption Factor (SAFe)

For dose reconstruction, it is not necessary to determine “true” activity of SMT materials, due to 

beta energy self-absorption. In Section 2 of the Mound Technical Basis Document for Stable 

Tritiated Particles and Organically Bound Tritium (SRDB Ref ID 32921), it was demonstrated 

that apparent or “observed” activity on swipe samples is a better indicator of dose or dose 

potential than “true” activity. Moreover, it was demonstrated that knowledge of the specific SMT 

material and its size distribution are essentially unimportant to radiological protection. A simple 

radioassay for collected tritium is sufficient. For the purposes of this paper, it is necessary to 

determine the efficiency of the PC-5 proportional counter for counting SMTs.

The PC-5 gas proportional counter was generally used to count tritium contamination control 

swipes at Mound prior to August 1993. The PC-5 is a “gross beta” counter with variable beta 

ray detection efficiency that is proportional to the energy of the beta emission. Consequently,

the PC-5 data are reported in counts per minute (cpm). In order for a PC-5 counter result to be 

quantitative and be reported in units of disintegrations per minute (dpm), a calibration factor 

must be determined. 

By 1990, the Packard “Tricarb” liquid scintillation LS counter was introduced at Mound for 

quantitative measurement of tritium on contamination control swipes. For tritium compounds, 

(e.g., tritiated water) that completely dissolve in the counting cocktail, LS systems are able to 

provide quantitative results because the factors that affect counting efficiency are measured and 

compensated using the transformed spectral index of the external standard quench parameter 

called tSIE. An additional self-absorption correction factor is required for compounds that are 

not soluble in the LS cocktail. 

By definition, SMTs are relatively insoluble in lung fluids and LS cocktail so the assumption of 

complete solubility is not valid. The energy from beta rays originating inside a SMT particle can 

be absorbed inside the particle before reaching the particle surface where it becomes available 

for measurement or for delivery of dose to the surrounding tissue. For low energy beta rays 

(average 5.7 keV) emitted during the decay of tritium, self absorption can approach 100% when 
Rev. 0 Potential Stable Metal Tritide Exposures at the Mound Laboratory 03-30-12

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the particles are large (> 10 μm) because only the energy from betas emitted from the particle 

surface are available for measurement. Conversely, self-absorption can approach 0% for 

extremely small particles on the nanometer scale. The first step in establishing a counting 

efficiency for the PC-5 is to develop a correction factor for self-absorption applicable in the LS 

counts. That requires knowledge of the SMT particle size.

The following calculation assumes that the swipe counted in the LS counter detects 

chemically-pure metal tritide particles, and that all of the released beta emissions (surface 

activity) are measured as apparent dpm. This dpm measurement is converted to mass 

(Equation A-3), volume of a spherical particle (Equation A-4) and the diameter of that spherical 

particle (Equation A-5). The SAFe is determined through the application of Equation A-8.

The measurements from the LS counter are converted to corrected activity (total beta in dpm) 

using the SAFe in Equation A-9. Equation A-10 is then used to calculate the efficiency of the 

PC-5 proportional counter for tritium betas.

 ( ) ( )

 

 

 

 ( )

 A 

 ( 

) ( )

 

 

 

 ( )

 

 

 ( )

 A 

Where:

A = Uncorrected tritium activity in dpm as measured by the LS counter

SpAct = Specific activity of SMT

ρ = SMT density

2.22 ×1012 = Value for converting dpm to Ci
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An examination of the Self Absorption Factors (SAFs) using the ρ and SpAct data available in 

published literature indicated that the SAFs were fairly insensitive to these data and that the 

effect of self-absorption was slightly less pronounced for the compounds that had higher ρ and 

SpAct values. Therefore, the higher ρ and SpAct values are used in this study and they are 

nominally in the range of 11-12 g/cm3and 2-3 Ci/g, respectively.

Based on the equation for the volume of a sphere, 

 

 

 

 

, and , the diameter of the 

metal tritide particle (d) in μm is calculated as shown in Equation A-5.

 ( ) √

 

 

 

 

 

 

 A 5 

Tsoulfanidis (1991) described a method for calculating the self-absorption factor (SAF) in 

spherical particles. Building on that work, Knopf, Wang et al. (1998) developed a numerical 

method to evaluate the self absorption factor of tritium beta rays (SAFβ), which is the fraction of 

beta rays escaping the particle, and for SAFe, which is the fraction of the beta energy that 

escapes a spherical particle. The SAFe is a better quantity for correction of LS counting 

efficiency because almost any amount of beta energy deposited in the LS cocktail will result in a 

count being recorded in the tritium “window.” The SAFe is also appropriate for dosimetry 

calculations because almost any amount of ionization from a beta decay that reaches living 

tissue can impart dose.

Equations A-6 and A-7 define the SAFe as a function of tritide particle size (d). Figure A-9

illustrates the SAFβ and SAFe results as function of particle size.

 

 

 

for d . 5 μm A 

 for d . 5 μm A 
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Tritium swipe counting records are available documenting the results of swipes counted on both 

an LS counter and on a PC-5 system (SRDB Ref IDs: 81787, pdf pp. 8-247; 81788, pdf pp. 

2-628; 81907, pdf pp. 425-700; 81908, pdf pp. 58-62; 81909, pdf pp. 2-692). A sample of 356 of 

these data pairs were transcribed for evaluation in a spreadsheet titled “Mound LSC & PC5 

Comparison” (Sources: SRDB Ref IDs: 81787, pdf pp. 28-38, 44, 50, 60, 70, 80, 90, 100, 110; 

81788, pdf pp. 2, 20). The PC-5 counting efficiency value for each paired sample (discussed 

below) is calculated by dividing the PC-5 count rate in cpm by the self-absorption-corrected LS 

counter activity in dpm. The sample of 356 pairs was reduced to 292 pairs by eliminating the 14 

instances in which the PC-5 counting efficiency was 0%, and the 50 instances in which the PC-5 

efficiency was judged to be implausibly high based on operating experiences of using a 

proportional counter for tritium counting (i.e., > 5%). All subsequent calculations are based on 

the 292 paired samples.

Figure A-9: Self-absorption Factors for Beta Particles and Beta Energy in SMT
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The particle diameter distribution derived from the 292 pairs of count data can be fit to a 

lognormal distribution with a GM = 2.8 μm and GSD = 1.5. Figure A-10 illustrates the data and 

the fitted distribution. The great majority of particles represented by this distribution would be 

respirable. The default particle size assumption of 5 μm used in dose reconstruction is 

reasonably consistent with this distribution. The assumption that all activity is in a single particle 

is both bounding and favorable to the claimant. If the activity is more finely divided and 

distributed into more abundant but smaller particles, the SAFe for each particle would be higher 

and the total activity would be lower. 

The particle diameter calculated in Equation A-5 can be used in Equation A-6 to determine the 

SAFe as a function of activity in the particle. Results of these calculations for a few activities of 

interest are shown in Table A-2. Figure A-11 presents the SAFe as a function of SMT particle 

activity.

SMT Particle Diameter, μm

Figure A-10: Metal Tritide Particle Diameter Distribution

Calculated from Uncorrected LS Counter Data

Hafnium Tritide Particle Diameter, um Frequency

Distribution

Lognormal

0 3 6 9 12

0

20

40

60

80

100
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Table A-2: SMT Particle Mass, Diameter and Self-absorption Factor for Tritium Beta Rays (SAFe) 

as a Function of the Uncorrected Activity of SMT Measured in the LS Counter

Measured Activity

(dpm)

Particle mass

(ng)

Particle diameter

(μm)

SAFe

1 0.00018 0.31 0.58

10 0.0018 0.66 0.36

100 0.018 1.4 0.20

1000 0.18 3.1 0.10

10000 1.8 6.6 0.050

20000 3.5 8.3 0.040

Figure A-11: SAFe as a Function of SMT Particle Activity

Activity, dpm, in spherical SMT particle
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When the nominal values for specific activity and density are used, Equation A-4, Equation A-5,

and Equation A-6 can be combined and simplified, resulting in Equation 8:

 

( ) 

 

 √ 

 

 A 

The 292 SAFe values can be fit to a lognormal distribution with a GM = 0.118 and GSD = 1.4, as 

shown in Figure A-12.

Figure A-12: Calculated SAFe Values Fitted to a Lognormal Distribution

The self-absorption of beta rays by the SMT particles in swipes can be substantial and should 

be used to correct the nominal liquid scintillation counting efficiency. This can be accomplished 

by dividing the reported LS swipe activity (A) values by the corresponding SAFe(A) values, as 

shown in Equation A-9.

 

 

 ( )

 A 

SAFe frequency

Distribution

Lognormal

0 0.1 0.2 0.3 0.4

0

10

20

30

40

50

60
Rev. 0 Potential Stable Metal Tritide Exposures at the Mound Laboratory 03-30-12

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The quotient of the ordered pairs representing the PC-5 count rate in cpm, and self-absorptioncorrected LS counter activity in dpm, can be used to estimate the PC-5 counting efficiency, as 

shown in Equation A-10.

 

 

 

 A 

The counting efficiencies of the 292 values, illustrated in Figure A-13, can be fit to a lognormal 

distribution with an arithmetic mean = 0.016, a GM = 0.011, and GSD = 2.2. The GM, nominally 

1%, is assumed to represent the SMT counting efficiency of the PC-5.

Figure A-13: PC-5 Counting Efficiency for SMT

The SAFe can also be used as a multiplicative factor to adjust the calculated dose to lung tissue 

from SMT particles. Energy from beta decay that does not deposit in living tissue does not 

contribute to dose. In other words, lower tissue doses result when the SAFe is included in the 

dose calculation. The dosimetry model for tritium compounds implemented in IMBA does not 

include the SAFe (ORAUT 2007); however, a best estimate of dose would require this factor to 

PC-5 Counting Efficiency, c/d frequency

Distribution

Lognormal

0 0.01 0.02 0.03 0.04 0.05

0

10

20

30

40

50

60
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be included. The SAFe should be applied to the lung and esophagus because the SMT particle 

is the dominant chemical form in these organs. Most other tissues are irradiated by tritium in 

the form of HTO (which dissolves from the SMT), so use of the SAFe is not appropriate. A few 

tissues (e.g., stomach wall and colon) could be irradiated by both chemical forms. To ensure a 

conservative dose calculation, SAFe would not be applied to organs outside the respiratory tract. 

Equation A-11 presents the organ/tissue dose calculation modified by the SAFe for use in best 

estimate respiratory tract doses associated with SMT.

  AWhere:

HT = Corrected dose to respiratory tract tissues

DT = Absorbed dose in tissue T

WR = Radiation weighting factor

WT = Tissue weighting factor

Based on the above discussion, it is concluded that a PC-5 counter efficiency of 1% and a 

median SAFe value of 0.12 should be incorporated in lung dose calculations. 

A 4.0 Resuspension factor (RF)

A resuspension factor of 5 ×10-5 m

-1 was selected for use in this study. This value came from 

ORAUT-OTIB-0070, Dose Reconstruction During Residual Radioactivity Periods at Atomic 

Weapons Employer Facilities, and is the highest of the four resuspension factors cited in the 

OTIB. OTIB-00070 compiles the following resuspension factors recommended to be used for 

dose assessments by DOE and NRC. 

Based on their studies, DOE recommended that a value of 10-6 m

-1

be used under quiescent 

conditions and a factor of 10 higher (10-5 m

-1

) be used under conditions of moderate activity. 

The NRC initially proposed a resuspension factor of 5 × 10-5 m

-1

to be used but later revised to 
Rev. 0 Potential Stable Metal Tritide Exposures at the Mound Laboratory 03-30-12

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9.6 × 10-7 m

-1

based on the fact that fresh deposits are not likely to be encountered at 

decommissioned facilities. 

A 5.0 Dose Conversion Factors

The annual DCFs were calculated with IMBA. For calculating intake and dose from SMTs, 

NIOSH uses the guidance in ORAUT-OTIB-0066 (ORAUT 2007). This publication implements 

the recommendations for SMT aerosols in ICRP Publication 71. Because intakes were 

calculated based on air concentrations rather than urine bioassay, the modifications to the urine 

bioassay model discussed in ORAUT-OTIB-0066 were not necessary. IMBA was used to 

generate a table of annual dose equivalents per unit intake for Type S, 5-μm activity median 

aerodynamic diameter (AMAD) SMTs for various organs. DCFs were calculated for the nine 

organs projected to receive the highest total doses over an extended period (50 years). These 

organs were all from the respiratory and gastrointestinal tracts. Table A-3 lists the organs for 

which dose conversion factors were calculated.

Table A-3: Target Organ Designations and Descriptions

Organ Description

SI Small Intestine

ULI Upper large intestine

LLI Lower large intestine

ET Extrathoracic

Lung Lung

Colon Colon

LN(ET) Lymphatics and lymph nodes that drain the ET region

Al Alveolar interstitial

LN(TH) Lymphatics and lymph nodes that drain the thoracic region

The results of the IMBA calculations appear in Table A-4. DCF for the lung reflects the 

application of the SAFe and the CDE is the sum for the 50-year period.
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Table A-4: Annual Dose Equivalents Per Unit Intake to Various Organs for 50 Years

Year

Dose Conversion Factors (rem/μCi)

SI ULI LLI ET Lung(1) Colon LN(ET) Al LN(TH)

1 2.75E-05 1.65E-04 4.82E-04 6.89E-07 1.27E-04 3.02E-04 2.17E-04 3.18E-03 5.61E-04

2 4.23E-07 2.27E-06 6.56E-06 6.16E-07 8.02E-05 4.13E-06 5.16E-04 2.01E-03 7.94E-04

3 2.71E-07 1.45E-06 4.17E-06 7.36E-07 5.48E-05 2.63E-06 6.70E-04 1.37E-03 8.26E-04

4 1.76E-07 9.30E-07 2.68E-06 7.82E-07 3.84E-05 1.69E-06 7.37E-04 9.59E-04 8.41E-04

5 1.16E-07 6.01E-07 1.73E-06 7.83E-07 2.76E-05 1.09E-06 7.52E-04 6.88E-04 8.43E-04

6 7.68E-08 3.92E-07 1.13E-06 7.60E-07 2.04E-05 7.09E-07 7.39E-04 5.07E-04 8.37E-04

7 5.16E-08 2.57E-07 7.34E-07 7.19E-07 1.54E-05 4.64E-07 7.03E-04 3.82E-04 8.19E-04

8 3.54E-08 1.71E-07 4.87E-07 6.73E-07 1.19E-05 3.08E-07 6.61E-04 2.97E-04 7.97E-04

9 2.48E-08 1.16E-07 3.27E-07 6.24E-07 9.51E-06 2.07E-07 6.16E-04 2.36E-04 7.71E-04

10 1.78E-08 8.01E-08 2.24E-07 5.78E-07 7.76E-06 1.42E-07 5.71E-04 1.92E-04 7.43E-04

11 1.31E-08 5.62E-08 1.56E-07 5.29E-07 6.40E-06 9.94E-08 5.24E-04 1.58E-04 7.09E-04

12 9.94E-09 4.06E-08 1.12E-07 4.85E-07 5.38E-06 7.13E-08 4.81E-04 1.33E-04 6.76E-04

13 7.73E-09 3.01E-08 8.18E-08 4.44E-07 4.57E-06 5.24E-08 4.41E-04 1.13E-04 6.42E-04

14 6.18E-09 2.29E-08 6.17E-08 4.07E-07 3.93E-06 3.97E-08 4.04E-04 9.66E-05 6.09E-04

15 5.02E-09 1.78E-08 4.74E-08 3.71E-07 3.39E-06 3.06E-08 3.68E-04 8.31E-05 5.73E-04

16 4.16E-09 1.42E-08 3.75E-08 3.38E-07 2.94E-06 2.43E-08 3.36E-04 7.21E-05 5.39E-04

17 3.50E-09 1.16E-08 3.02E-08 3.09E-07 2.57E-06 1.96E-08 3.07E-04 6.28E-05 5.06E-04

18 2.99E-09 9.58E-09 2.49E-08 2.82E-07 2.25E-06 1.62E-08 2.80E-04 5.50E-05 4.76E-04

19 2.56E-09 8.02E-09 2.07E-08 2.56E-07 1.97E-06 1.35E-08 2.55E-04 4.80E-05 4.44E-04

20 2.22E-09 6.80E-09 1.74E-08 2.34E-07 1.73E-06 1.14E-08 2.33E-04 4.21E-05 4.14E-04

21 1.93E-09 5.81E-09 1.48E-08 2.13E-07 1.52E-06 9.70E-09 2.12E-04 3.69E-05 3.86E-04

22 1.69E-09 5.02E-09 1.27E-08 1.95E-07 1.34E-06 8.35E-09 1.94E-04 3.26E-05 3.61E-04

23 1.48E-09 4.32E-09 1.09E-08 1.77E-07 1.18E-06 7.18E-09 1.76E-04 2.86E-05 3.34E-04

24 1.30E-09 3.75E-09 9.44E-09 1.61E-07 1.04E-06 6.21E-09 1.61E-04 2.52E-05 3.10E-04

25 1.14E-09 3.27E-09 8.19E-09 1.47E-07 9.20E-07 5.39E-09 1.46E-04 2.22E-05 2.88E-04

26 1.01E-09 2.86E-09 7.13E-09 1.34E-07 8.15E-07 4.71E-09 1.34E-04 1.96E-05 2.68E-04

27 8.90E-10 2.49E-09 6.19E-09 1.22E-07 7.18E-07 4.09E-09 1.22E-04 1.72E-05 2.47E-04

28 7.86E-10 2.18E-09 5.40E-09 1.11E-07 6.35E-07 3.57E-09 1.11E-04 1.52E-05 2.28E-04

29 6.95E-10 1.90E-09 4.71E-09 1.02E-07 5.62E-07 3.12E-09 1.01E-04 1.34E-05 2.11E-04
Rev. 0 Potential Stable Metal Tritide Exposures at the Mound Laboratory 03-30-12

This is a working document prepared by NIOSH 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 Privacy Act 5 

USC §552a and has been cleared for distribution.

Page 33 of 42

Table A-4: Annual Dose Equivalents Per Unit Intake to Various Organs for 50 Years

Year

Dose Conversion Factors (rem/μCi)

SI ULI LLI ET Lung(1) Colon LN(ET) Al LN(TH)

30 6.16E-10 1.67E-09 4.12E-09 9.27E-08 4.98E-07 2.73E-09 9.23E-05 1.19E-05 1.95E-04

31 5.44E-10 1.46E-09 3.59E-09 8.43E-08 4.40E-07 2.38E-09 8.39E-05 1.05E-05 1.80E-04

32 4.82E-10 1.28E-09 3.14E-09 7.68E-08 3.90E-07 2.08E-09 7.65E-05 9.26E-06 1.66E-04

33 4.27E-10 1.12E-09 2.74E-09 7.00E-08 3.46E-07 1.82E-09 6.97E-05 8.19E-06 1.53E-04

34 3.80E-10 9.89E-10 2.40E-09 6.40E-08 3.07E-07 1.60E-09 6.37E-05 7.26E-06 1.41E-04

35 3.36E-10 8.66E-10 2.10E-09 5.82E-08 2.72E-07 1.40E-09 5.79E-05 6.41E-06 1.30E-04

36 2.98E-10 7.60E-10 1.83E-09 5.30E-08 2.41E-07 1.22E-09 5.28E-05 5.68E-06 1.19E-04

37 2.65E-10 6.68E-10 1.60E-09 4.83E-08 2.14E-07 1.07E-09 4.81E-05 5.03E-06 1.10E-04

38 2.36E-10 5.89E-10 1.41E-09 4.42E-08 1.91E-07 9.42E-10 4.40E-05 4.47E-06 1.01E-04

39 2.09E-10 5.16E-10 1.23E-09 4.01E-08 1.69E-07 8.23E-10 4.00E-05 3.95E-06 9.26E-05

40 1.86E-10 4.54E-10 1.07E-09 3.66E-08 1.50E-07 7.22E-10 3.65E-05 3.51E-06 8.50E-05

41 1.65E-10 3.99E-10 9.40E-10 3.33E-08 1.34E-07 6.33E-10 3.32E-05 3.11E-06 7.81E-05

42 1.48E-10 3.52E-10 8.25E-10 3.05E-08 1.19E-07 5.57E-10 3.04E-05 2.77E-06 7.18E-05

43 1.31E-10 3.09E-10 7.21E-10 2.77E-08 1.06E-07 4.87E-10 2.76E-05 2.45E-06 6.57E-05

44 1.17E-10 2.72E-10 6.31E-10 2.52E-08 9.44E-08 4.27E-10 2.52E-05 2.18E-06 6.03E-05

45 1.04E-10 2.39E-10 5.53E-10 2.30E-08 8.41E-08 3.75E-10 2.29E-05 1.94E-06 5.53E-05

46 9.30E-11 2.11E-10 4.86E-10 2.10E-08 7.52E-08 3.30E-10 2.10E-05 1.73E-06 5.08E-05

47 8.27E-11 1.86E-10 4.24E-10 1.91E-08 6.69E-08 2.89E-10 1.91E-05 1.54E-06 4.64E-05

48 7.39E-11 1.64E-10 3.72E-10 1.74E-08 5.97E-08 2.54E-10 1.74E-05 1.37E-06 4.25E-05

49 6.60E-11 1.44E-10 3.26E-10 1.59E-08 5.34E-08 2.23E-10 1.58E-05 1.22E-06 3.90E-05

50 5.90E-11 1.27E-10 2.86E-10 1.45E-08 4.77E-08 1.96E-10 1.44E-05 1.09E-06 3.57E-05

CDE 2.88E-05 1.71E-04 5.01E-04 1.29E-05 4.41E-04 3.14E-04 1.21E-02 1.10E-02 1.81E-02

(1) = SAFe of 0.12 applied
Rev. 0 Potential Stable Metal Tritide Exposures at the Mound Laboratory 03-30-12

This is a working document prepared by NIOSH 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 Privacy Act 5 

USC §552a and has been cleared for distribution.

Page 34 of 42

A 6.0 Results

Substituting the parameters given in the above sections into Equation (A-1) yields the following 

results:

 The resulting representative SMT concentrations derived from the median and

95th-percentile swipe sample results for the years from 1968 to 1989 for all four rooms

(Figures A-14 and A-15).

 The resulting 50 annual DEs to the critical organ (lung) from a total intake of SMT in a 

single year for the two highest swipe count years (Table A-1) for the period from 1968 to 

1989 (Tables A-5 and A-6). Dose Equivalent values in Tables A-5 and A-6 are used for 

the Dose Reconstruction Case Study. 

Figure A-14: Representative SMT Bounding (95th Percentile) Concentrations from 1968 to 1989

0.00E+00

5.00E-04

1.00E-03

1.50E-03

2.00E-03

2.50E-03

3.00E-03

3.50E-03

4.00E-03

4.50E-03

5.00E-03

1968196919701971197219731974197519761977197819791980198119821983198419851986198719881989

95%tile SMT Concentrations (μCi/m3) 

SW-150

SW-13

SW-8

R-108
Rev. 0 Potential Stable Metal Tritide Exposures at the Mound Laboratory 03-30-12

This is a working document prepared by NIOSH 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 Privacy Act 5 

USC §552a and has been cleared for distribution.

Page 35 of 42

Figure A-15: Representative SMT Best Estimate (Median) Concentrations from 1968 to 1989

0.00E+00

2.00E-04

4.00E-04

6.00E-04

8.00E-04

1.00E-03

1.20E-03

1.40E-03

1.60E-03

1968196919701971197219731974197519761977197819791980198119821983198419851986198719881989

50%tile SMT Concentrations (μCi/m3) 

SW-150

SW-13

SW-8

R-108
Rev. 0 Potential Stable Metal Tritide Exposures at the Mound Laboratory 03-30-12

This is a working document prepared by NIOSH 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 Privacy Act 5 

USC §552a and has been cleared for distribution.

Page 36 of 42

Table A-5: Annual Lung Dose Equivalent (mrem) for the Two Highest Swipe Count Years (Table A-1) in 

Rooms SW-150 and SW-13 for the Period 1968 to 1989

Year

SW-150 SW-13

Bounding (95%tile) Best Estimate (50%tile) Bounding (95%tile) Best Estimate (50%tile)

1968 1977 1968 1977 1974 1975 1974 1975

1 4.99E-02 4.81E-02 1.26E-02 1.25E-02 3.43E-02 3.91E-02 1.19E-02 9.10E-03

2 3.15E-02 3.03E-02 7.95E-03 7.89E-03 2.16E-02 2.46E-02 7.53E-03 5.74E-03

3 2.15E-02 2.07E-02 5.44E-03 5.39E-03 1.48E-02 1.68E-02 5.15E-03 3.92E-03

4 1.51E-02 1.45E-02 3.81E-03 3.78E-03 1.04E-02 1.18E-02 3.61E-03 2.75E-03

5 1.08E-02 1.04E-02 2.74E-03 2.71E-03 7.44E-03 8.47E-03 2.59E-03 1.97E-03

6 8.00E-03 7.70E-03 2.02E-03 2.00E-03 5.49E-03 6.26E-03 1.91E-03 1.46E-03

7 6.03E-03 5.81E-03 1.52E-03 1.51E-03 4.14E-03 4.72E-03 1.44E-03 1.10E-03

8 4.69E-03 4.52E-03 1.18E-03 1.18E-03 3.22E-03 3.67E-03 1.12E-03 8.54E-04

9 3.73E-03 3.60E-03 9.43E-04 9.35E-04 2.56E-03 2.92E-03 8.93E-04 6.80E-04

10 3.04E-03 2.93E-03 7.69E-04 7.63E-04 2.09E-03 2.38E-03 7.28E-04 5.55E-04

11 2.51E-03 2.42E-03 6.35E-04 6.30E-04 1.73E-03 1.97E-03 6.01E-04 4.58E-04

12 2.11E-03 2.03E-03 5.33E-04 5.29E-04 1.45E-03 1.65E-03 5.05E-04 3.85E-04

13 1.80E-03 1.73E-03 4.54E-04 4.50E-04 1.23E-03 1.40E-03 4.29E-04 3.27E-04

14 1.54E-03 1.49E-03 3.90E-04 3.87E-04 1.06E-03 1.21E-03 3.69E-04 2.81E-04

15 1.33E-03 1.28E-03 3.36E-04 3.33E-04 9.14E-04 1.04E-03 3.18E-04 2.42E-04

16 1.16E-03 1.11E-03 2.92E-04 2.90E-04 7.94E-04 9.04E-04 2.76E-04 2.11E-04

17 1.01E-03 9.71E-04 2.55E-04 2.53E-04 6.92E-04 7.89E-04 2.41E-04 1.84E-04

18 8.84E-04 8.52E-04 2.23E-04 2.21E-04 6.07E-04 6.92E-04 2.11E-04 1.61E-04

19 7.74E-04 7.45E-04 1.95E-04 1.94E-04 5.31E-04 6.05E-04 1.85E-04 1.41E-04

20 6.79E-04 6.54E-04 1.72E-04 1.70E-04 4.67E-04 5.31E-04 1.62E-04 1.24E-04

21 5.98E-04 5.76E-04 1.51E-04 1.50E-04 4.11E-04 4.68E-04 1.43E-04 1.09E-04

22 5.28E-04 5.08E-04 1.33E-04 1.32E-04 3.62E-04 4.13E-04 1.26E-04 9.61E-05

23 4.64E-04 4.47E-04 1.17E-04 1.16E-04 3.19E-04 3.63E-04 1.11E-04 8.45E-05

24 4.09E-04 3.94E-04 1.03E-04 1.02E-04 2.81E-04 3.20E-04 9.78E-05 7.45E-05

25 3.61E-04 3.48E-04 9.12E-05 9.05E-05 2.48E-04 2.83E-04 8.63E-05 6.58E-05

26 3.20E-04 3.08E-04 8.08E-05 8.01E-05 2.20E-04 2.50E-04 7.65E-05 5.83E-05

27 2.82E-04 2.71E-04 7.12E-05 7.06E-05 1.94E-04 2.20E-04 6.74E-05 5.13E-05
Rev. 0 Potential Stable Metal Tritide Exposures at the Mound Laboratory 03-30-12

This is a working document prepared by NIOSH 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 Privacy Act 5 

USC §552a and has been cleared for distribution.

Page 37 of 42

Table A-5: Annual Lung Dose Equivalent (mrem) for the Two Highest Swipe Count Years (Table A-1) in 

Rooms SW-150 and SW-13 for the Period 1968 to 1989

Year

SW-150 SW-13

Bounding (95%tile) Best Estimate (50%tile) Bounding (95%tile) Best Estimate (50%tile)

1968 1977 1968 1977 1974 1975 1974 1975

28 2.49E-04 2.40E-04 6.30E-05 6.24E-05 1.71E-04 1.95E-04 5.96E-05 4.54E-05

29 2.21E-04 2.12E-04 5.57E-05 5.52E-05 1.51E-04 1.72E-04 5.27E-05 4.02E-05

30 1.96E-04 1.88E-04 4.94E-05 4.90E-05 1.34E-04 1.53E-04 4.68E-05 3.56E-05

31 1.73E-04 1.66E-04 4.36E-05 4.33E-05 1.19E-04 1.35E-04 4.13E-05 3.15E-05

32 1.53E-04 1.47E-04 3.87E-05 3.83E-05 1.05E-04 1.20E-04 3.66E-05 2.79E-05

33 1.36E-04 1.31E-04 3.43E-05 3.40E-05 9.32E-05 1.06E-04 3.24E-05 2.47E-05

34 1.21E-04 1.16E-04 3.05E-05 3.02E-05 8.28E-05 9.43E-05 2.88E-05 2.20E-05

35 1.07E-04 1.03E-04 2.69E-05 2.67E-05 7.33E-05 8.35E-05 2.55E-05 1.94E-05

36 9.47E-05 9.12E-05 2.39E-05 2.37E-05 6.50E-05 7.41E-05 2.26E-05 1.72E-05

37 8.41E-05 8.10E-05 2.12E-05 2.11E-05 5.77E-05 6.58E-05 2.01E-05 1.53E-05

38 7.49E-05 7.21E-05 1.89E-05 1.88E-05 5.14E-05 5.86E-05 1.79E-05 1.36E-05

39 6.64E-05 6.39E-05 1.68E-05 1.66E-05 4.56E-05 5.19E-05 1.59E-05 1.21E-05

40 5.90E-05 5.69E-05 1.49E-05 1.48E-05 4.05E-05 4.62E-05 1.41E-05 1.08E-05

41 5.25E-05 5.06E-05 1.33E-05 1.32E-05 3.61E-05 4.11E-05 1.26E-05 9.57E-06

42 4.68E-05 4.51E-05 1.18E-05 1.17E-05 3.22E-05 3.66E-05 1.12E-05 8.53E-06

43 4.16E-05 4.01E-05 1.05E-05 1.04E-05 2.86E-05 3.25E-05 9.94E-06 7.58E-06

44 3.71E-05 3.57E-05 9.36E-06 9.28E-06 2.55E-05 2.90E-05 8.86E-06 6.75E-06

45 3.30E-05 3.18E-05 8.34E-06 8.27E-06 2.27E-05 2.58E-05 7.90E-06 6.02E-06

46 2.95E-05 2.84E-05 7.46E-06 7.40E-06 2.03E-05 2.31E-05 7.06E-06 5.38E-06

47 2.63E-05 2.53E-05 6.64E-06 6.58E-06 1.80E-05 2.06E-05 6.28E-06 4.79E-06

48 2.35E-05 2.26E-05 5.92E-06 5.88E-06 1.61E-05 1.83E-05 5.61E-06 4.27E-06

49 2.09E-05 2.02E-05 5.29E-06 5.25E-06 1.44E-05 1.64E-05 5.01E-06 3.82E-06

50 1.87E-05 1.80E-05 4.73E-06 4.69E-06 1.29E-05 1.46E-05 4.47E-06 3.41E-06
Rev. 0 Potential Stable Metal Tritide Exposures at the Mound Laboratory 03-30-12

This is a working document prepared by NIOSH 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 Privacy Act 5 

USC §552a and has been cleared for distribution.

Page 38 of 42

Table A-6: Annual Lung Dose Equivalent (mrem) for the Two Highest Swipe Count Years (Table A-1) in 

Rooms R-108 and SW-8 for the Period 1968 to 1989

Year R-108 SW-8

Bounding (95%tile) Best Estimate (50%tile) Bounding (95%tile) Best Estimate (50%tile)

1984 1985 1985 1989 1975 1977 1969 1986

1 2.21E-02 3.01E-02 5.97E-03 4.70E-03 5.99E-02 9.28E-02 3.47E-02 4.96E-03

2 1.39E-02 1.90E-02 3.77E-03 2.96E-03 3.78E-02 5.85E-02 2.19E-02 3.13E-03

3 9.52E-03 1.30E-02 2.57E-03 2.03E-03 2.58E-02 4.00E-02 1.50E-02 2.14E-03

4 6.67E-03 9.09E-03 1.80E-03 1.42E-03 1.81E-02 2.80E-02 1.05E-02 1.50E-03

5 4.79E-03 6.53E-03 1.30E-03 1.02E-03 1.30E-02 2.01E-02 7.53E-03 1.08E-03

6 3.54E-03 4.82E-03 9.57E-04 7.53E-04 9.60E-03 1.49E-02 5.56E-03 7.95E-04

7 2.67E-03 3.64E-03 7.22E-04 5.68E-04 7.24E-03 1.12E-02 4.19E-03 6.00E-04

8 2.07E-03 2.83E-03 5.61E-04 4.41E-04 5.63E-03 8.72E-03 3.26E-03 4.66E-04

9 1.65E-03 2.25E-03 4.47E-04 3.51E-04 4.48E-03 6.94E-03 2.60E-03 3.71E-04

10 1.35E-03 1.83E-03 3.64E-04 2.86E-04 3.65E-03 5.66E-03 2.12E-03 3.03E-04

11 1.11E-03 1.51E-03 3.01E-04 2.36E-04 3.02E-03 4.67E-03 1.75E-03 2.50E-04

12 9.34E-04 1.27E-03 2.53E-04 1.99E-04 2.53E-03 3.93E-03 1.47E-03 2.10E-04

13 7.94E-04 1.08E-03 2.15E-04 1.69E-04 2.15E-03 3.34E-03 1.25E-03 1.78E-04

14 6.83E-04 9.31E-04 1.85E-04 1.45E-04 1.85E-03 2.87E-03 1.07E-03 1.53E-04

15 5.88E-04 8.02E-04 1.59E-04 1.25E-04 1.60E-03 2.47E-03 9.25E-04 1.32E-04

16 5.11E-04 6.97E-04 1.38E-04 1.09E-04 1.39E-03 2.15E-03 8.03E-04 1.15E-04

17 4.46E-04 6.07E-04 1.21E-04 9.48E-05 1.21E-03 1.87E-03 7.01E-04 1.00E-04

18 3.91E-04 5.33E-04 1.06E-04 8.32E-05 1.06E-03 1.64E-03 6.14E-04 8.79E-05

19 3.42E-04 4.66E-04 9.25E-05 7.28E-05 9.28E-04 1.44E-03 5.38E-04 7.69E-05

20 3.00E-04 4.09E-04 8.12E-05 6.39E-05 8.15E-04 1.26E-03 4.72E-04 6.75E-05

21 2.64E-04 3.60E-04 7.15E-05 5.62E-05 7.17E-04 1.11E-03 4.15E-04 5.94E-05

22 2.33E-04 3.18E-04 6.31E-05 4.96E-05 6.33E-04 9.81E-04 3.67E-04 5.24E-05

23 2.05E-04 2.79E-04 5.55E-05 4.36E-05 5.56E-04 8.62E-04 3.22E-04 4.61E-05

24 1.81E-04 2.47E-04 4.89E-05 3.85E-05 4.91E-04 7.60E-04 2.84E-04 4.07E-05

25 1.60E-04 2.18E-04 4.32E-05 3.40E-05 4.33E-04 6.71E-04 2.51E-04 3.59E-05

26 1.41E-04 1.93E-04 3.83E-05 3.01E-05 3.84E-04 5.95E-04 2.22E-04 3.18E-05

27 1.25E-04 1.70E-04 3.37E-05 2.65E-05 3.38E-04 5.24E-04 1.96E-04 2.80E-05
Rev. 0 Potential Stable Metal Tritide Exposures at the Mound Laboratory 03-30-12

This is a working document prepared by NIOSH 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 Privacy Act 5 

USC §552a and has been cleared for distribution.

Page 39 of 42

Table A-6: Annual Lung Dose Equivalent (mrem) for the Two Highest Swipe Count Years (Table A-1) in 

Rooms R-108 and SW-8 for the Period 1968 to 1989

Year R-108 SW-8

Bounding (95%tile) Best Estimate (50%tile) Bounding (95%tile) Best Estimate (50%tile)

1984 1985 1985 1989 1975 1977 1969 1986

28 1.10E-04 1.50E-04 2.98E-05 2.34E-05 2.99E-04 4.63E-04 1.73E-04 2.48E-05

29 9.75E-05 1.33E-04 2.64E-05 2.07E-05 2.65E-04 4.10E-04 1.53E-04 2.19E-05

30 8.65E-05 1.18E-04 2.34E-05 1.84E-05 2.35E-04 3.64E-04 1.36E-04 1.94E-05

31 7.64E-05 1.04E-04 2.07E-05 1.63E-05 2.07E-04 3.21E-04 1.20E-04 1.72E-05

32 6.77E-05 9.22E-05 1.83E-05 1.44E-05 1.84E-04 2.84E-04 1.06E-04 1.52E-05

33 6.00E-05 8.18E-05 1.62E-05 1.28E-05 1.63E-04 2.52E-04 9.43E-05 1.35E-05

34 5.33E-05 7.27E-05 1.44E-05 1.13E-05 1.45E-04 2.24E-04 8.38E-05 1.20E-05

35 4.72E-05 6.43E-05 1.28E-05 1.00E-05 1.28E-04 1.98E-04 7.41E-05 1.06E-05

36 4.19E-05 5.71E-05 1.13E-05 8.91E-06 1.14E-04 1.76E-04 6.58E-05 9.41E-06

37 3.72E-05 5.07E-05 1.01E-05 7.91E-06 1.01E-04 1.56E-04 5.84E-05 8.36E-06

38 3.31E-05 4.51E-05 8.96E-06 7.05E-06 8.99E-05 1.39E-04 5.21E-05 7.44E-06

39 2.94E-05 4.00E-05 7.94E-06 6.24E-06 7.96E-05 1.23E-04 4.61E-05 6.60E-06

40 2.61E-05 3.56E-05 7.06E-06 5.55E-06 7.08E-05 1.10E-04 4.10E-05 5.87E-06

41 2.32E-05 3.17E-05 6.28E-06 4.94E-06 6.30E-05 9.76E-05 3.65E-05 5.22E-06

42 2.07E-05 2.82E-05 5.60E-06 4.41E-06 5.62E-05 8.71E-05 3.26E-05 4.66E-06

43 1.84E-05 2.51E-05 4.98E-06 3.91E-06 4.99E-05 7.73E-05 2.89E-05 4.13E-06

44 1.64E-05 2.23E-05 4.43E-06 3.49E-06 4.45E-05 6.89E-05 2.58E-05 3.68E-06

45 1.46E-05 1.99E-05 3.95E-06 3.11E-06 3.96E-05 6.14E-05 2.30E-05 3.28E-06

46 1.31E-05 1.78E-05 3.53E-06 2.78E-06 3.54E-05 5.49E-05 2.05E-05 2.93E-06

47 1.16E-05 1.58E-05 3.14E-06 2.47E-06 3.15E-05 4.88E-05 1.83E-05 2.61E-06

48 1.04E-05 1.41E-05 2.81E-06 2.21E-06 2.81E-05 4.36E-05 1.63E-05 2.33E-06

49 9.26E-06 1.26E-05 2.51E-06 1.97E-06 2.51E-05 3.89E-05 1.46E-05 2.08E-06

50 8.28E-06 1.13E-05 2.24E-06 1.76E-06 2.25E-05 3.48E-05 1.30E-05 1.86E-06
Rev. 0 Potential Stable Metal Tritide Exposures at the Mound Laboratory 03-30-12

This is a working document prepared by NIOSH 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 Privacy Act 5 

USC §552a and has been cleared for distribution.

Page 40 of 42

A 7.0 References

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Rev. 0 Potential Stable Metal Tritide Exposures at the Mound Laboratory 03-30-12

This is a working document prepared by NIOSH 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 Privacy Act 5 

USC §552a and has been cleared for distribution.

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Rev. 0 Potential Stable Metal Tritide Exposures at the Mound Laboratory 03-30-12

This is a working document prepared by NIOSH 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 Privacy Act 5 

USC §552a and has been cleared for distribution.

Page 42 of 42

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