External Dose Assessment from X-ray 

Diffraction at Carborundum Company,
 

Niagara Falls, NY
 

Response Paper 

Rev. 01 

National Institute for Occupational Safety and Health 

June 13, 2016 

Elyse Thomas, CHP
 

Oak Ridge Associated Universities Team
 

Reviewed by: James W. Neton, Ph.D., CHP 

Thomas P. Tomes 

Division of Compensation Analysis and Support 

Page 1 of 10 

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) 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 the Privacy Act 5 USC §552a and has been cleared for distribution. 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

External Dose Assessment from X-ray Diffraction at Carborundum Company, Niagara Falls, NY 

INTRODUCTION 

As a subcontractor to United Nuclear Corporation, the Carborundum Company (Buffalo Ave., 

Niagara Falls, NY) manufactured ceramic fuel pellets containing PuC-UC. The fuel pellets were 

evaluated by various means, including X-ray diffraction (XRD) analysis (Breslin, 1960, pg. 5). 

The X-ray powder diffraction method is used very extensively for compound or phase 

identification (Gundaker, 1971, pg. 28); Carborundum employed this method to analyze the fuel 

as part of the fuel fabrication process. 

NOTE: During the Sanford Cohen and Associates (SC&A) review of the SEC-00223 

Carborundum Evaluation Report (SC&A 2016), reviewers raised various issues related 

to XRD. A summary of SC&A’s XRD comments and the corresponding NIOSH 

responses are provided in an Attachment at the end of this paper. 

DESCRIPTION OF THE X-RAY DIFFRACTION MACHINE AT CARBORUNDUM 

XRD machines can have a range of sizes and configurations, from bench-top units or stand-alone 

devices within a laboratory. The operator’s position during operation is also variable, depending 

on the configuration of the XRD machine. 

Both SC&A and NIOSH interviewed a former Carborundum worker who used the XRD machine 

(SC&A 2016; Jessen, 2016). In the interview with NIOSH, the worker was specifically asked 

about the configuration of the XRD machine. The worker stated that the XRD machine sat on 

the floor and was not moved because water was plumbed to it. He stated that people could walk 

through the room where the XRD unit was located, but that generally only the people who 

worked with one of the three analytical devices in the room occupied it. According to the 

worker, these people (about five total) “knew not to stand around” (Jessen, 2016, pg. 2). This 

worker further stated that the XRD machine operated for about 40 minutes per sample, with 

about 10 sample runs per day. 

The interviewed worker also described some technical details of Carborundum’s XRD machine. 

He mentioned that the machine had a “hood” and a shield. He described preparing the sample, 

placing it in the XRD machine (with the shutter closed), closing the shield over the assembly, 

and then opening the shutter to irradiate the sample. Once the assembly was in place, the worker 

stated that he walked away (Jessen, 2016, pg. 2). 

DESCRIPTION OF THE HAZARD FROM X-RAY DIFFRACTION MACHINES 

Page 2 of 10 

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) 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 the Privacy Act 5 USC §552a and has been cleared for distribution. 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

External Dose Assessment from X-ray Diffraction at Carborundum Company, Niagara Falls, NY 

The greatest hazard from XRD machines is from external exposure to the primary beam. This 

can occur most commonly during alignment procedures, during which the target must be aligned 

with the output port, the sample with the primary beam, and the detector or film holder with the 

reflected beam (Lubenau, 1969). The primary beam of Kα characteristic X-rays has a very small 

area, on the order of 0.01 cm2 at the exit port (Rudman, 1971, pg. 82). This primary beam is 

very intense, with an exposure rate in the hundreds of thousands of R/sec (Thomas, 1971, pg. 

145). If the X-ray tube is energized during alignment, the operator’s fingers or hands may be 

exposed to the primary beam. Historically, these types of accidents are the major hazard from 

XRD machines (Thomas, 1971, pg. 145). No evidence of these types of radiation accidents has 

been found at Carborundum. 

Other than exposure to the primary beam, an operator of an XRD machine would be exposed to 

leakage, diffracted radiation, and scatter radiation from the sample and other components. Each 

of these has slightly different properties, as discussed below. 

Leakage from the tube housing is assumed to be minimal (De Castro 1986, pg. 10). 

The source of the low-energy X-rays striking the sample is the Kα characteristic X-rays from the 

tube target materials, commonly copper or iron. There is evidence that Carborundum used an 

XRD unit with a copper target (Strasser, 1963, pg. 30; Carborundum, 1965, pg. 101). The 

former XRD machine operator at Carborundum interviewed by both SC&A and NIOSH stated 

that the XRD machine had a copper target (SC&A, 2016, pg. 48; Jessen, 2016, pg. 3). Based on 

the evidence in two historical documents from Carborundum, and the two different interviews of 

this worker, NIOSH believes the XRD machine at Carborundum had a copper target. The 

energy of the Kα,1 characteristic X-ray of copper is 8.1 keV (Lubenau, 1969). 

The diffracted radiation would be emitted from the sample with an energy of 8.1 keV in small, 

directional beams. Given that the interviewed worker stated that the XRD machine had a shield 

over the entire assembly (Jessen 2016, pg. 2), it is assumed that most of the diffracted radiation 

would have been absorbed in the shield material. 

Electrons accelerated through a potential difference of about 35-50 kV (typical of a copper target 

tube) produce a Bremsstrahlung X-ray spectrum in addition to the characteristic X-rays of 

copper. The average energy of the Bremsstrahlung photons is about 20 keV (Block, 1971, pg. 

20). The scatter radiation emitted isotropically with an average energy of about 20 keV is 

assumed to be the major exposure source to workers in the XRD laboratory. Air attenuation can 

be quite large at low energies (Granlund, 1971, pg. 181), but is ignored in this work. 

Page 3 of 10 

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) 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 the Privacy Act 5 USC §552a and has been cleared for distribution. 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

External Dose Assessment from X-ray Diffraction at Carborundum Company, Niagara Falls, NY 

DOSE FROM SCATTERED X-RAY BEAM CALCULATION 

Lubenau, et al (1969) provides measurements of scatter from a 1966 survey of XRD units in the 

state of Pennsylvania. Scatter measurements for three XRD units with copper targets are 

provided, ranging from 0.5 -2.0 mR/hour at the table edge. These measurements are reported as 

maximum scatter values from the respective machines during operation. The highest scatter 

measurement of 2.0 mR/hour will be used as the starting point for dose assessment for 

Carborundum. Lubenau does not specify the measurement distance, so a 30 cm distance will be 

assumed as a practical distance from an enclosure or barrier for making a measurement (NBS 

Handbook 93, pg. 9). 

Measurement of low-energy X-rays (8-20 keV) may require correction because most ion 

chamber survey instruments are calibrated at the much higher photon energy from Cs-137 (662 

keV). Lubenau (1969) used a Victoreen 440RF ion chamber when measuring scatter from XRD 

machines in Pennsylvania. Els (1971) provides an instrument correction factor of about 2.5 for a 

Victoreen 440 RF ion chamber measuring 8 keV photons diffracted from a copper target. The 

correction for measuring 20 keV photons (average energy of scatter from a 50 kV X-ray source) 

drops to approximately 1. With the assumption that the major source of worker exposure is the 

scatter radiation of 20 keV average energy, the instrument correction factor is not necessary. 

According to the XRD machine operator interviewed by NIOSH (Jessen 2016, pg. 3), the 

run-time of the XRD machine was 40 minutes/sample, with about 10 samples/day. Over the 

course of 50 weeks, the total run-time would be 1,667 hours/year. The operator stated that once 

the sample was loaded into the XRD machine, he would “close the shield” over the assembly, 

open the shutter to expose the sample, and then walk away. The operator’s time near the XRD 

machine after closing the shield and opening the shutter is estimated to be about 2 minutes per 

sample, or 5% of the time for a total exposure of 83.3 hours/year. Given this description of the 

XRD configuration and set-up procedure by one of the machine operators, the exposure to the 

hands and to the whole body are assumed to be the same. NIOSH considers this estimate 

conservative, as there were undoubtedly other operators who performed some portion of the total 

workload. 

Page 4 of 10 

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) 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 the Privacy Act 5 USC §552a and has been cleared for distribution. 

Assumptions: 

1.	 The worker (operator) is exposed near the XRD machine for about 5% of the total run-time, 

or about 83.3 hours/year. 

2.	 The worker (operator) is exposed to the scattered radiation, not the primary beam. Accidents 

involving the primary beam would have to be assessed separately on a case-by-case basis. 

Small, diffracted beams of 8 keV are assumed to be absorbed in the shield or covering over 
 

 

 

 

 

 

 

 

 

 

	 

External Dose Assessment from X-ray Diffraction at Carborundum Company, Niagara Falls, NY 

the device and are not considered in the dose assessment. Leakage from the tube housing is 

assumed to be minimal, and therefore, is not considered in the dose assessment. 

3.	 Scatter from the copper target and other components is emitted in all directions 

(isotropically) with an average energy of about 20 keV for a machine operated at 50 kV 

(Block, 1971, pg. 20). 

Page 5 of 10 

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) 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 the Privacy Act 5 USC §552a and has been cleared for distribution. 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

	 

	 

	 

	 

External Dose Assessment from X-ray Diffraction at Carborundum Company, Niagara Falls, NY 

Calculations: 

1.	 Scattered radiation exposure rate at 30 cm from the nearest accessible surface: 2.0 mR/hour 

(Lubenau, et al., 1969). 

2.	 Scattered beam exposure rate corrected for occupancy: 

a.	 Occupancy is estimated at 5% of total run-time of 1,667 hours/year, or 83.3 hours/year. 

b.	 Exposure rate to the whole body and the hands: 

yearR

year

mR

year

hours

hour

mR 0.2 83 3. 166  .07. 1667 /

3. Conversion to air kerma (Ka) 

= 

year

R

.0 1667

* 

R

Gy .8 E  0376

= 

year

Gy .1 E  0346

4. Organ Dose = 

year

Gy .1 E  0346

* Organ Dose Conversion Factor (ICRP, 1997) 

Table 1: Example of Organ Doses 

Organ Air Kerma (Gy/year) ODCFa (Gy/Gy) Equivalent Doseb (rem/year) 

Lens of the 

Eye 

1.46E-03 0.912 1.33E-01 

Skin 1.46E-03 0.488 7.12E-02 rem 

Thyroid 1.46E-03 0.358 5.23E-02 rem 

Bladder 1.46E-03 0.0895 1.31E-02 rem 

a ODCF is for absorbed dose per unit air kerma free-in-air for 20 keV photons, AP geometry, Tables A-2 

through A-20 (ICRP, 1997). 

b Organ dose converted from Gy to rad, then rad to rem with a radiation weighting factor of 1 for photons. 

Page 6 of 10 

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) 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 the Privacy Act 5 USC §552a and has been cleared for distribution. 
 

 

 

 

 

 

 

 

 

 

 

External Dose Assessment from X-ray Diffraction at Carborundum Company, Niagara Falls, NY 

REFERENCES 

ANSI, General Safety Standard for Installations Using Non-Medical X-ray and Sealed GammaRay Sources Energies up to 10 MeV; NBS Handbook No. 114; American National Standards 

Institute N543-1974 [SRDB Ref ID: 154955] 

Block, S., American National Standard Radiation Safety for X-ray Diffraction and Fluorescence 

Analysis Equipment; American National Standards Institute N43.2-1971 [SRDB Ref ID: 20839] 

Breslin, A.J., Carborundum Company Feasibility Report for Fabrication of Plutonium Carbide 

Pellets; June 6, 1960 [SRDB Ref ID: 19739] 

Carborundum Company, The Carborundum Company Annual Report 1965; 1965 [SRDB Ref 

ID: 141412] 

De Castro, T. M., Dosimetry of X-ray Beams: The Measure of the Problem; August 1986 [SRDB 

Ref ID: 21582] 

Els, R. A., The Response of Various Survey Instruments to Low Energy X-rays; U.S. Department 

of Health Education and Welfare; 1971 [SRDB Ref ID: 32635] 

Granlund, R., Routine Radiation Monitoring; U.S. Department of Health Education and Welfare; 

1971 [SRDB Ref ID: 32635] 

Gundaker, E., Radiation Safety in X-ray Diffraction and Spectroscopy; U.S. Department of 

Health Education and Welfare; 1971 [SRDB Ref ID: 32635] 

International Commission on Radiation Protection (ICRP), Publication 74, Conversion 

Coefficients for use in Radiological Protection against External Radiation, 1997. [SRDB Ref ID: 

7979] 

Jessen, K., Interview Notes with [name redacted], May 12, 2016. [SRDB Ref ID: 156589] 

Page 7 of 10 

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) 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 the Privacy Act 5 USC §552a and has been cleared for distribution. 
 

 

 

 

 

 

 

 

External Dose Assessment from X-ray Diffraction at Carborundum Company, Niagara Falls, NY 

Lubenau, J., et al., Analytical X-ray Hazards: A Continuing Problem; Health Physics 16:739-

746; December 1969 [SRDB Ref ID: 14296] 

National Bureau of Standards, Safety Standard for Non-Medical X-ray and Sealed Gamma-Ray 

Sources, Handbook 93; 1964 [SRDB Ref ID: 11306] 

Rudman, R., Survey of X-ray Diffraction and X-ray Spectroscopy Equipment; U.S. Department 

of Health Education and Welfare; 1971 [SRDB Ref ID: 32635] 

Sanford Cohen and Associates, Review of the Carborundum Special Exposure Cohort (SEC) 

Petition-00223 and the NIOSH SEC Petition Evaluation Report, SC&A-TR-SEC-2016-

0001/Carborundum SEC Petition Review, January 27, 2016. 

Strasser, A., et al, Carbide Fuel Development Phase IV Report Period of September 15, 1961 to 

September 30, 1962 [SRDB Ref ID: 65097] 

Thomas, J.W., Radiation Safety: Objectives and Considerations; U.S. Department of Health 

Education and Welfare; 1971 [SRDB Ref ID: 32635] 

Page 8 of 10 

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) 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 the Privacy Act 5 USC §552a and has been cleared for distribution. 
 

 

 

 

 

 

 

 


 


 


 

External Dose Assessment from X-ray Diffraction at Carborundum Company, Niagara Falls, NY 

ATTACHMENT:
 

NIOSH RESPONSE TO SC&A COMMENTS
 

ON X-RAY DIFFRACTION AT CARBORUNDUM
 

June 7, 2016 

Elyse Thomas, CHP, ORAUT 

During the SC&A review of the SEC-00223 Carborundum Evaluation Report (SC&A 2016), 

reviewers raised various issues related to XRD. A summary of SC&A’s XRD comments and the 

corresponding NIOSH responses are provided below. 

Summary of SC&A comments: 

1.	 Information provided in SEC-00223 ER, Section 7.3.3.1, not detailed enough for DR. 

2.	 NIOSH assumed the worker’s body was at or beyond the table edge, and hand dose would be 

higher. 

3.	 A low energy correction factor should be applied to Lubenau’s measured scatter value that is 

used by NIOSH as the starting point for dose assessment. 

4.	 Lubenau’s measured scatter value should be interpreted as an isotropic field measurement. 

5.	 SC&A does not believe the XRD unit at Carborundum used a copper target. 

6.	 Need specific DR methods for XRD. 

Summary of NIOSH responses: 

1.	 Agreed, NIOSH will provide a more detailed description of the DR method for assessment of 

dose from XRD at Carborundum: 

a.	 Start with the published exposure rate from scatter radiation. 

b.	 Estimate the exposure time based on information from the worker interview. 

c.	 Use ICRP 74 ODCF to calculate organ dose. 

2.	 As a result of information obtained from a worker interview about the configuration of 

Carborundum’s XRD machine, and the fact that the worker did not remain in the area, 

NIOSH did not see a need for a separate dose assessment to the skin of the hands. 

Page 9 of 10 

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) 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 the Privacy Act 5 USC §552a and has been cleared for distribution. 
 

 

 

 

 

 

 

 

 

	 

	 

	 

	 

External Dose Assessment from X-ray Diffraction at Carborundum Company, Niagara Falls, NY 

3.	 Agreed, a low energy correction factor would need to be applied to measurements of 

low-energy X-rays in the 8-20 keV range (characteristic X-rays from copper). However, the 

new approach assumes the characteristic X-rays from copper are absorbed in the shield 

covering the XRD machine. The exposure to the operator is considered to be from an 

isotropic emission of scatter radiation with average energy of 20 keV. At this energy, the 

correction factor is approximately 1, and therefore, not used. 

4.	 Agreed, Lubenau’s measured scatter value will be interpreted as an isotropic field 

measurement. 

5.	 Based on worker interviews and historical documents, NIOSH believes that Carborundum’s 

XRD unit had a copper target. 

6.	 NIOSH will develop specific DR methods for XRD. 

Page 10 of 10 

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) 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 the Privacy Act 5 USC §552a and has been cleared for distribution.