SEC Petition Evaluation Report 

Petition SEC-00173 

Report Rev #: Addendum 1 Report Submittal Date: August 4, 2011

Subject Expert(s): Mike Mahathy

Site Expert(s): N/A

Petition Administrative Summary

Petition Under Evaluation

Petition # Petition 

Type

Petition

Receipt Date

Qualification 

Date

DOE/AWE Facility Name

SEC-00173 83.13 May 17, 2010 July 21, 2010 Norton Co.

Petitioner Class Definition 

All employees of the Norton Company who worked in any building or area at the Norton Company location on 

New Bond Street in Worcester, Massachusetts, from 1960 through 1972.

Class Evaluated by NIOSH

All atomic weapons employees who worked in any building or area at the facility owned by the Norton Co. in 

Worcester, Massachusetts, during the residual radiation period from January 1, 1958 through October 31, 2009. 

NIOSH-Proposed Class to be Added to the SEC

All Atomic Weapons Employer employees who worked in any building or area at the facility owned by the

Norton Co. (or a subsequent owner) in Worcester, Massachusetts, during the period from January 1, 1958 through 

October 10, 1962, for a number of work days aggregating at least 250 work days, occurring either solely under 

this employment or in combination with work days within the parameters established for one or more other 

classes of employees included in the Special Exposure Cohort.

Related Petition Summary Information 

SEC Petition 

Tracking #(s)

Petition 

Type

DOE/AWE 

Facility Name Petition Status

SEC-00148

SEC-00173

83.14

83.13

Norton Co.

Norton Co.

Class added to SEC for January 1, 1945-December 31, 1957

Class added to SEC for January 1, 1958-October 10, 1962

Related Evaluation Report Information 

Report Title DOE/AWE Facility 

Name

SEC Petition Evaluation Report for Petition SEC-00148 (January 1, 1945 through 

December 31, 1957) 

SEC Petition Evaluation Report for Petition SEC-00173 (January 1, 1958 through 

October 31, 2009)

Norton Co.

Norton Co. 

ORAU Lead Technical Evaluator: Mike Mahathy ORAU Peer Review Completed By: Michael Kubiak

Peer Review Completed By: [Signature on File] 8/5/2011 

Frank C. Crawford Date

[Signature on File] 8/8/2011 SEC Petition Evaluation Reviewed By:

J. W. Neton Date

[Signature on File] 8/8/2011 SEC Evaluation Approved By:

Stuart L. Hinnefeld Date
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Addendum to Norton Co. (SEC-00173) 

Special Exposure Cohort Evaluation Report 

ATTRIBUTION AND ANNOTATION: This is a single-author document. All conclusions drawn from 

the data presented in this evaluation were made by the ORAU Team Lead Technical Evaluator: Mike 

Mahathy, Oak Ridge Associated Universities. The rationales for all conclusions in this document are 

explained in the associated text.

NIOSH presented a Special Exposure Cohort (SEC) evaluation report (NIOSH, 2011) regarding the 

Norton Company for the period from January 1, 1958 through October 31, 2009 to the Advisory 

Board on Radiation and Worker Health (Advisory Board) during the Advisory Board’s meeting held 

February 23-25, 2011. In its report, NIOSH evaluated the feasibility of reconstructing radiation doses 

of all atomic weapons employees who worked in any building or area at the facility owned by the 

Norton Co. in Worcester, Massachusetts, during the residual radiation period from January 1, 1958 

through October 31, 2009. Based on its full research of the class under evaluation, NIOSH 

determined that decontamination and decommissioning activities were conducted during the period 

from January 1, 1958 through October 10, 1962, for which NIOSH has insufficient source term and 

monitoring data to bound internal and external doses potentially received from exposures during that 

work. As such, NIOSH defined a single class of employees for which NIOSH cannot estimate 

radiation doses with sufficient accuracy. The NIOSH-proposed class included all atomic weapons 

employees who worked in any building or area at the facility owned by the Norton Co. (or a 

subsequent owner) in Worcester, Massachusetts, during the period from January 1, 1958 through 

October 10, 1962, for a number of work days aggregating at least 250 work days, occurring either 

solely under this employment or in combination with work days within the parameters established for 

one or more other classes of employees included in the SEC. The class was added to the SEC, 

effective May 29, 2011. 

Further, NIOSH found that it does have sufficient data to bound doses for the period from October 11, 

1962 through October 31, 2009 (NIOSH 2011). NIOSH proposed to use guidance in ORAUT-OTIB0070 to bound doses potentially received from exposures to residual uranium, thoria, and thoron. In 

its proposal to bound residual radiation period doses starting October 11, 1962, NIOSH used the 

residual activity depletion rate of 1% per day as described in ORAUT-OTIB-0070. Since the 

publication of SEC Petition Evaluation Report for Petition SEC-00173, Norton Co. (NIOSH, 2011), 

NIOSH has studied source-term depletion at other Atomic Weapons Employer sites and has revised 

its depletion-rate guidance to now specify a value of 0.067% per day. This addendum provides 

discussion of the revised depletion rate and subsequent changes in annual intake rates and annual 

external dose rates during the Norton Co. residual radiation period from October 11, 1962 through 

October 31, 2009. The dose reconstruction feasibility conclusions published in SEC Petition 

Evaluation Report for Petition SEC-00173, Norton Co. (NIOSH, 2011) are not impacted by the 

changes discussed in this addendum. That is, NIOSH still concludes that it lacks sufficient monitoring 

records, process descriptions, and source term data to complete dose reconstructions for the evaluated 

class of employees for the period from January 1, 1958 through October 10, 1962. However, 

available monitoring records, process descriptions, and source term data are sufficient to complete 

dose reconstructions for the evaluated class of employees for the period from October 11, 1962 

through October 31, 2009. 
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NOTE: This SEC-00173 Evaluation Report Addendum only addresses those sections and the 

content in the Norton Co. SEC-00173 Evaluation Report (NIOSH, 2011) that require discussion; 

therefore, the section numbering is not contiguous. The sections requiring additional discussion 

begin below. 

Evaluation Report Summary 

NIOSH-Proposed Class to be Added to the SEC

NIOSH finds that it does have sufficient data to bound doses for the period from October 11, 1962 

through October 31, 2009 (the end of the designated residual radiation period). For this period, 

NIOSH has obtained gross alpha air monitoring results collected at Norton Co. near the end of the 

Atomic Weapons Employer (AWE) operations period and during the residual radiation period. Using 

those data, guidance in ORAUT-OTIB-0070, and empirical source-term depletion-rate information, 

NIOSH can bound the internal doses potentially received from exposures to residual uranium and 

thoria. NIOSH can use the same set of gross alpha data to bound potential internal doses received 

from thoron by using decay and in-growth calculations on sample recounts. The gross alpha air 

contamination data from the operational period and the methods described in Battelle-TBD-6000 

allow NIOSH to bound external doses from residual uranium and thoria. 

Feasibility of Dose Reconstruction

The NIOSH dose reconstruction feasibility findings are based on the following: 

Note: Bullets 1-5 are unchanged. 

• NIOSH has identified sufficient information and data to support bounding internal dose for the 

remaining portion of the residual radiation period (October 11, 1962 through October 31, 2009) 

using air monitoring data obtained during the operational period, empirical source-term depletionrate information, and guidance given in ORAUT-OTIB-0070, Dose Reconstruction during 

Residual Radioactivity Periods at Atomic Weapons Employer Facilities. 

Note: Bullets 7-9 are unchanged. 

7.2.2 Methods for Bounding Residual Radiation Period Internal Dose at Norton Co. 

NIOSH does not have adequate internal monitoring or workplace monitoring data to bound doses that 

were potentially received during the dismantling, clean-up, packaging, and burial of AWE materials 

and contamination. While NIOSH does have air monitor data obtained during the AWE operations 

period that can be used to bound doses in the residual period following the burial which culminated on 

October 10, 1962, those data cannot be assumed to bound all radioactive contamination and 

radiological contamination levels that could have arisen from the dismantling, clean-up, packaging 

and burial processes which were documented to have generated dust. 

In order to determine the feasibility of bounding potential internal doses received from exposures to 

residual radiation received after the burial of AWE materials, NIOSH evaluated air monitoring data in 

the form of long-lived gross-alpha results obtained on May 13, 1958 (reported on May 28, 1958) by 
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the Massachusetts Department of Labor and Industries (Pagnotto, 1958) to derive the air concentration 

starting on October 11, 1962 through the end of the residual radiation period, October 31, 2009. The 

average of the long-lived alpha results was calculated from the data shown in Table 7-1 to estimate the 

starting air concentration (4.662 dpm/m3

) on October 11, 1962. 

Table 7-1: Air Monitoring Results, Long-Lived Alpha Emitters

Sample 

Number

Time 

Sampling 

Completed 

(hours)

Location

Long-Lived 

Alpha Emitters 

(uCi/mL)

Thorium Air 

Concentration 

(dpm/m3) 

1M 9.2 End of hood - thoria area 4E-13 - 

7M 2.5 End of hood - thoria area 4E-13 - 

13 2.5 End of hood - thoria area 2E-12 - 

5M 1.15 Thoria processing area 2E-12 - 

3 10 General area on bench 2E-12 - 

7 11.2 Hood - thoria area 1E-12 - 

11 2 Bench near thoria area 2E-12 - 

14 2.5 By glass cutting wheel 7E-12 - 

Average - thoria area samples 2.1E-12 4.662

Average daily intake rates for inhalation and ingestion were calculated based on an inhalation rate of 

1.2 m3

/hr, 8-hour workday, and 250 workdays per year, resulting in a value of 30.654 dpm/day for the 

period from October 11, 1962 through December 31, 1963. Intake rates for the following years 

through October 31, 2009 have been adjusted according to an empirically-derived source-term 

depletion rate. NIOSH has previously determined the activity removal rates during the residual 

radiation periods for the four sites shown in Table 7-1A (DCAS-TKBS-0002; Battelle-TBD-6000 

Appendix C; ORAUT-TKBS-0045; ORAUT-TKBS-0032). In these cases, contemporary estimates of 

airborne radioactivity at the beginning and end of each site’s residual radiation period were used to 

estimate the effective exponential clearance of the contamination over an extended period of time for 

each site (ORAUT-OTIB-0070). The source-term depletion rates calculated for these sites are 

provided in Table 7-1A below. 

Note: This is a new table that is not in SEC Petition Evaluation Report for Petition SEC-00173, 

Norton Co (NIOSH, 2011). This table does not replace an existing table. 

Table 7-1A: Source-Term Depletion Rates During Residual Period

Facility Depletion Rate (per day)

Blockson 0.00076

Dow Madison 0.00027

General Atomics 0.00116

Simonds Saw and Steel 0.00049

Average 0.00067
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Because these values were empirically derived at operating facilities, NIOSH considers them more 

appropriate than a value based solely on theoretical considerations. As such, the 1% per day depletion 

rate proposed for the residual radiation period in SEC Petition Evaluation Report for Petition SEC00173, Norton Co. (NIOSH, 2011) is being replaced by the average value of 0.067% per day, as 

calculated using the data in Table 7-1A. 

The Norton Co. air monitoring results are reported in units of gross alpha and are not isotopicspecific; therefore, the most claimant-favorable radionuclide and solubility class will be assigned by 

NIOSH. The Norton Co. processed both uranium oxide and thoria. Because Norton Co. processed 

both uranium and thorium oxides, uranium can be assumed to be U-234 (Types M and S) and thorium 

can be assumed to be Th-232 (Types M and S). The calculated intake rates are shown in Table 7-2. 

Table 7-2: Intake Rates for Uranium or Thorium

Applicable Period

Source Term 

Depletion

Adjustment

Inhalation 

(dpm/day)

Ingestion 

(dpm/day) Distribution

01/1958 - 10/10/1962 not feasible not feasible not feasible N/A

10/11/1962 - 12/31/1963 1.000 30.654 0.747 Constant

1964 0.783 24.002 0.585 Constant

1965 0.613 18.791 0.458 Constant

1966 0.480 14.714 0.359 Constant

1967 0.376 11.526 0.281 Constant

1968 0.294 9.012 0.220 Constant

1969 0.231 7.081 0.173 Constant

1970 0.181 5.548 0.135 Constant

1971 0.141 4.322 0.105 Constant

1972 0.111 3.403 0.083 Constant

1973 0.087 2.667 0.065 Constant

1974 0.068 2.084 0.051 Constant

1975 0.053 1.625 0.040 Constant

1976 0.042 1.287 0.031 Constant

1977 0.033 1.012 0.025 Constant

1978 0.026 0.797 0.019 Constant

1979 0.020 0.613 0.015 Constant

1980 0.016 0.490 0.012 Constant

1981 0.012 0.368 0.009 Constant

1982 0.010 0.307 0.007 Constant

1983 0.008 0.245 0.006 Constant

1984 0.006 0.184 0.004 Constant

1985 0.005 0.153 0.004 Constant

1986 0.004 0.123 0.003 Constant

1987 0.003 0.092 0.002 Constant

1988 0.002 0.061 0.001 Constant

1989 0.002 0.061 0.001 Constant

1990 0.001 0.031 0.001 Constant

1991 0.001 0.031 0.001 Constant

1992 0.001 0.031 0.001 Constant

1993 and later 0.001 0.031 0.001 Constant
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NIOSH does not consider radon as an exposure source, as Norton Co. only had uranium metals and 

associated dust onsite. NIOSH has identified thoron monitoring data in the form of short-lived thoria 

results obtained on May 13, 1958 (reported on May 28, 1958) (Pagnotto, 1958). NIOSH used the 

reported average short-lived values as actual values of thoron, as provided in Table 7-3 to calculate 

the intake rate of thoron from the end of the burial operation through December 31, 1963. Working 

level (WL) and working level months (WLM) were calculated for each result and for the average of 

the reported short-lived results.

Table 7-3: Air Monitoring Results, Short-Lived Alpha Emitters

Sample 

Number

Time Sampling 

Completed 

(hours)

Location

Short-Lived 

Alpha Emitters 

(uCi/mL)

Thoron 

(WL)

Thoron 

(WLM)

1M 9.2 End of hood - thoria area 3.3E-11 0.00440 0.0518

7M 2.5 End of hood - thoria area 4E-11 0.00533 0.0627

13 2.5 End of hood - thoria area 3.6E-11 0.00480 0.0565

5M 1.15 Thoria processing area 4.2E-11 0.00560 0.0659

3 10 General area on bench 5.2E-11 0.00693 0.0816

7 11.2 Hood - thoria area 4.1E-11 0.00547 0.0643

11 2 Bench near thoria area 2.26E-10 0.03013 0.3545

14 2.5 By glass cutting wheel 3.1E-11 0.00413 0.0486

Average - thoria area samples 6.2625E-11 0.00835 0.0982

Intake rates for the following years have been adjusted due to source term depletion per the discussion 

above (i.e., 0.067% per day depletion rate). Thoron intake rates for the Norton Co. residual radiation 

period are provided in Table 7-4. 

Table 7-4: Intake Rates for Thoron

(Table 7-4 spans two pages.)

Applicable Period ORAUT-OTIB-0070 

Adjustment

Thoron 

(WLM)) Distribution

01/1958 - 10/10/1962 not feasible not feasible N/A

10/11/1962 - 12/31/1963 1.000 0.0982 Constant

1964 0.783 0.077 Constant

1965 0.613 0.060 Constant

1966 0.480 0.047 Constant

1967 0.376 0.037 Constant

1968 0.294 0.029 Constant

1969 0.231 0.023 Constant

1970 0.181 0.018 Constant

1971 0.141 0.014 Constant

1972 0.111 0.011 Constant

1973 0.087 0.009 Constant

1974 0.068 0.007 Constant

1975 0.053 0.005 Constant

1976 0.042 0.004 Constant
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Table 7-4: Intake Rates for Thoron

(Table 7-4 spans two pages.)

Applicable Period ORAUT-OTIB-0070 

Adjustment

Thoron 

(WLM)) Distribution

1977 0.033 0.003 Constant

1978 0.026 0.003 Constant

1979 0.020 0.002 Constant

1980 0.016 0.002 Constant

1981 0.012 0.001 Constant

1982 0.010 0.001 Constant

1983 0.008 0.001 Constant

1984 0.006 0.001 Constant

1985 0.005 0.000 Constant

1986 0.004 0.000 Constant

1987 0.003 0.000 Constant

1988 0.002 0.000 Constant

1989 0.002 0.000 Constant

1990 0.001 0.000 Constant

1991 0.001 0.000 Constant

1992 0.001 0.000 Constant

1993 and later 0.001 0.000 Constant

7.3.3 Methods for Bounding Residual Radiation Period External Dose at Norton Co.

In order to determine the feasibility of bounding potential external doses received from exposures to 

residual radiation, NIOSH evaluated air monitoring data obtained during the operations period. The 

95th percentile of the gross alpha air dust results was calculated to estimate the highest contamination 

levels present after the AWE materials had been buried starting on October 11, 1962. It is assumed 

that the material deposited on the floor with a deposition velocity of 0.00075 m/s from October 11, 

1962 through December 31, 1963. This results in a maximum contamination level of 1.83×106

dpm/m2. Using these assumptions, daily doses can be calculated based on the maximizing potential 

radionuclide. The external doses are from penetrating photons with energies between 30 and 250 keV 

and electron energy range of >15 keV for penetrating exposures. Table 7-5 shows the external dose 

rates for the residual radiation period adjusted for the 0.067% per day source term depletion discussed 

in 7.2.2 above and per the guidance provided in ORAUT-OTIB-0070 and Battelle-TBD-6000. 

NIOSH has identified no personnel or workplace monitoring data that can be used to quantify such 

contamination or accurately bound external doses potentially received during the period from January 

1, 1958 through October 10, 1962, during the clean-up and burial operations. Therefore, NIOSH finds 

that it is not feasible to reconstruct doses received from potential external exposures to radioactive 

contamination during the period of January 1, 1958 through October 10, 1962. 
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Table 7-5: External Dose Rates for the Residual Radiation Period

Applicable Period

Source Term 

Depletion

Adjustment

Gamma 

(rem/year)

Beta

(rem/year) Distribution

01/1958 - 10/10/1962 not feasible not feasible not feasible N/A

10/11/1962 - 12/31/1963 1.000 0.026 0.233 Constant

1964 0.783 0.020 0.182 Constant

1965 0.613 0.016 0.143 Constant

1966 0.480 0.012 0.112 Constant

1967 0.376 0.010 0.088 Constant

1968 0.294 0.008 0.069 Constant

1969 0.231 0.006 0.054 Constant

1970 0.181 0.005 0.042 Constant

1971 0.141 0.004 0.033 Constant

1972 0.111 0.003 0.026 Constant

1973 0.087 0.002 0.020 Constant

1974 0.068 0.002 0.016 Constant

1975 0.053 0.001 0.012 Constant

1976 0.042 0.001 0.010 Constant

1977 0.033 0.001 0.008 Constant

1978 0.026 0.001 0.006 Constant

1979 0.020 0.001 0.005 Constant

1980 0.016 0.000 0.004 Constant

1981 0.012 0.000 0.003 Constant

1982 0.010 0.000 0.002 Constant

1983 0.008 0.000 0.002 Constant

1984 0.006 0.000 0.001 Constant

1985 0.005 0.000 0.001 Constant

1986 0.004 0.000 0.001 Constant

1987 0.003 0.000 0.001 Constant

1988 0.002 0.000 0.000 Constant

1989 0.002 0.000 0.000 Constant

1990 0.001 0.000 0.000 Constant

1991 0.001 0.000 0.000 Constant

1992 0.001 0.000 0.000 Constant

1993 and later 0.001 0.000 0.000 Constant

8.0 Evaluation of Health Endangerment for Petition SEC-00173 

Note: The first paragraph in this section was unchanged.

NIOSH has obtained gross alpha air monitoring results collected at the Norton Co. near the end of the 

AWE operations period and during the residual radiation period. Using those data, the guidance in 

ORAUT-OTIB-0070, and empirical depletion-rate information, NIOSH can bound the internal doses 

potentially received from exposures to residual uranium and thoria for the period from October 11, 

1962 through October 31, 2009. The gross alpha air contamination data from the operational period 
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and the methods described in Battelle-TBD-6000 allow NIOSH to bound external doses from residual 

uranium and thoria for the period from October 11, 1962 through October 31, 2009. NIOSH’s 

evaluation determined that it is feasible to estimate radiation dose for members of the NIOSHevaluated class for the period from October 11, 1962 through October 31, 2009, with sufficient 

accuracy based on the sum of information from available resources. Modification of the class 

definition regarding health endangerment and minimum required employment periods, therefore, is 

not required for the October 11, 1962 through October 31, 2009 period. However, NIOSH’s 

evaluation determined that it is not feasible to estimate radiation dose for members of the NIOSHevaluated class for the period from January 1, 1958 through October 10, 1962, with sufficient 

accuracy. Modification of the class definition regarding health endangerment and minimum required 

employment periods, therefore, is required for the January 1, 1958 through October 10, 1962 period. 
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10.0 References (for this Addendum)

Battelle-TBD-6000, Site Profiles for Atomic Weapons Employers that Worked Uranium and Thorium 

Metals, Rev. F0; Battelle Team Dose Reconstruction Project for NIOSH; December 13, 2006; SRDB 

Ref ID: 30671 

Battelle-TBD-6000 Appendix C, Site Profiles for Atomic Weapons Employers that Worked Uranium 

and Thorium Metals, Appendix C-Dow Chemical Co. (Madison Site), Rev. 0; Office of Compensation 

Analysis and Support; September 8, 2008; SRDB Ref ID: 49802 

DCAS-TKBS-0002, Technical Basis Document for Atomic Energy Operations at Blockson Chemical 

Company, Joliet, Illinois, Rev. 03; Division of Compensation Analysis and Support (DCAS); 

December 20, 2010; SRDB Ref ID: 91205 

NIOSH, 2011, SEC Petition Evaluation Report for Petition SEC-00173, Norton Co.; National Institute 

for Occupational Safety and Health (NIOSH); January 24, 2011; SRDB Ref ID: 94436 

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

Weapons Employer Facilities, Rev. 00; March 10, 2008; SRDB Ref ID: 41603 

ORAUT-TKBS-0032, Site Profile for Simonds Saw and Steel, Rev. 01; ORAU Team Dose 

Reconstruction Project for NIOSH; April 18, 2011; SRDB Ref ID: 94105 

ORAUT-TKBS-0045, Site Profile for General Atomics, Rev. 00; ORAU Team Dose Reconstruction 

Project for NIOSH; September 26, 2008; SRDB Ref ID: 49950 

Pagnotto, 1958, Study of Air Samples and Urinalysis Data (From May 13, 1958 Visit) in Regards to 

Thoria Handling, correspondence to Harvey Elkins; Leonard Pagnotto and Harold Bavley; May 28, 

1958; SRDB Ref ID: 78700, pdf pp. 3-5