National Institute for Occupational Safety and Health

 Division of Compensation Analysis and Support 

DEPARTMENT OF HEALTH & HUMAN SERVICES 

This working document was prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions with the 

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Memorandum 

To: Advisory Board’s Work Group on Kansas City Plant 

From: Peter Darnell, DCAS Health Physicist 

Pat McCloskey, ORAU Team Health Physicist 

Mutty Sharfi, ORAU Team Principal AWE Dosimetrist 

Subject: KCP suspension of Mg-Th operations 

Date: September 18, 2015 

NIOSH received SC&A’s memo, (Review of NIOSH Response to SC&A’s Review of Internal 

Exposures to Thorium and its Progeny at the KCP during Mg-Th Machining, July 7, 2015), and 

provides the following response. 

In their August 14, 2015 Memo, SC&A identified concerns with the NIOSH position that Mg-Th 

machining operations were suspended from April 1, 1963 through August 27, 1970. 

SC&A noted inventory references (SRDB 135987 and 137786) provided by NIOSH to 

corroborate the suspension “do not cover the period 1963–first semester of 1969”. However, 

NIOSH noted that in SRDB 135987 (Station AQA Statement of Measurement Methods 1969-

1978), the first mention of receiving shipments of Mg-Th is in August of 1971. Mg-Th was not 

listed in any prior letter. On page 50 of the pdf, there is a letter that points out they will start 

receiving Thorium in the form of Mg-Th. After that time, Mg-Th is listed on the receipt lists. 

NIOSH finds this to be reasonably strong evidence that there was not Mg-Th on site from at least 

July 1969 to August 27, 1970. 

Until NIOSH locates additional information that suggests KCP’s controlled machining 

operations did in fact occur during the suspension period, we will interpret the absence of 

records, including NMMS, to mean the operations were suspended. Interviews of former 

employees such as the following shed some light on the on-again off-again nature of KCP’s 

weapons support for Sandia, “The KCP has always been involved in special “piece-work,” that 

is, numerous, small, isolated projects relying on high-quality machining” (SRDB 127484 p. 9). 

SC&A notes that Department 20 was maintained as a Radiological. Area during the suspension 

period. NIOSH agrees that a small amount of Depleted Uranium machining occurred during the 

time in question; however, we do not find this to be an indication that Mg-Th machining also 

occurred. 

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SC&A notes that a June 24, 1965 memo (SRDB 123895, p. 155) citing machining of radioactive 

material, including “classified radioactive material”, indicates Mg-Th operations were not 

suspended. However, NIOSH is aware that certain DU machining operations were considered 

classified, and other operations such as the machining of DU oxide have been recently 

declassified (SRDB 127484, p. 6). Therefore, NIOSH does not interpret information that 

indicates work with classified radioactive material to necessarily mean Mg-Th machining. 

SC&A indicates that since there are uranium air monitoring records (SRDB 128373) for 

Department 20/22 during the suspension period, that there could have been ongoing Mg-Th 

work. However, NIOSH did not find thorium listed as the contaminant of concern on the 

referenced records, and because KCP has demonstrated the importance of listing thorium on 

records when it is appropriate (108264, p. 16), NIOSH disagrees with this assertion. 

SC&A concludes with, “there is no substantial evidence of the suspension of work with 

radioactive material in Department 22/20 during the entire April 1963 to August 1970 period. 

For the period 1963–1970, information remains lacking regarding the location, specific 

timeframe, and workload for Mg-Th machining.” 

NIOSH did not mean to imply there was a suspension of all Rad work, only Mg-Th. However, 

NIOSH agrees there is no document indicating Mg-Th machining was suspended. NIOSH will 

continue to search for more information, and will in the interim, rely on the bulk of evidence. 

SC&A recommended that NIOSH should do suitable sample dose reconstructions to illustrate the 

application of 3E-11 μCi/mL air concentration limit in a claimant-favorable scenario. NIOSH 

will provide those sample dose reconstructions to the Work group separately. 

Reviewed and Concurred by:

Date: 9/18/2015

Peter Darnell, CHP, RRPT

Health Physicist

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This working document was 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 document 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.