DRC-2016-011304 - 0901a06880682d26

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State of Utah
GARY R HERBERT
Governor
Spencer .1 Cox
Lieulenanl Governor
Department of
Environmental Quality
Alan Matheson
Executive Director
DIVISION OF WASTE MANAGEMENT
AND RADIATION CONTROL
Scott T Anderson
Director .
DRC-Z0i6-0U3n
MEMORANDUM
TO:
THROUGH:
FROM:
DATE:
File C-2016-87
Phil Goble, Section Manager /3E6
Russell J. Topham, P.E.
May 2,2016
SUBJECT: Yellowcake Dryer Inspection Module Development Recommendations. Radioactive
Materials License UT1900479 (License) - Energy Fuels Resources (USA) Inc. (EFR)
White Mesa Mill, Standing, Utah
The Nuclear Regulatory Commission (NRG), while conducting the Integrated Materials Performance
Evaluation Program (IMPEP) inspection of the Utah Agreement State Program between July 27 and 31,
2015, asked that the DWMRC develop a yellowcake dryer inspection module. This module would answer
concerns raised in the NRG Information Notice 1999-03, Revision 1, Exothermic Reactions Involving
Dried Uranium Oxide Powder (Yellowcake), dated March 4, 2014 (the Circular) and its attachment (the
Enclosure). Among the documents I reviewed are the identified circular and attachment, and a confidential
development draft of the EFR Standard Operating Procedure, Book 5, Section 2, Yellowcake Precipitation
- Drying and Packaging (the SOP). During an inspection trip to the White Mesa Mill, I took the
opportunity to explore the mill’s process chemistry, dryer operation, solvent extraction processes, and other
measures taken to provide a product that will not undergo chemical reactions following placement in
drums.
Based upon the information I have gathered, I recommend against establishing a dryer inspection module
for the process used at the White Mesa Mill. The following discussion provides my rationale.
The Circular chronicled nine incidents where operators had received drummed yellowcake that had
developed sufficient internal pressure following sealing of the drum lid to project yellowcake onto the
individual opening the drum. The investigations identified buildup of oxygen gas in sealed containers as
the fundamental cause of the incidents. Root cause analysis identified several factors that contributed, or
could contribute, to the pressure buildup in the drum. These root causes included “decomposition of
residual uranyl peroxide hydrates or hydrogen peroxide in the dried yellowcake product due to incomplete
drying, and the presence of organic contaminants in the finished product (Circular, p. 2).
Process Chemistry
The literature clearly identifies the use of ammonia rather than hydrogen peroxide as a process chemical
where chemical reactions proceeded following placement of the product in the drum (Enclosure, p. 1). The
195 North 1950 West • Salt Lake City, UT
Mailing Address. PO Box 144880 • Salt Lake Citv, UT 84114-4880
Telephone [phone] • Fax [phone] • T D D [phone]
umnv.deq.utnh.gov
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Project C-2016-87
Memorandum: Yellowcake Dryer Inspection Module Development
Page 2
White Mesa Mill uses ammonia rather than hydrogen peroxide. Thus, the chemistry discussed in the
Enclosure does not apply to this case.
Drying Process Unit
According to the Enclosure, the use of a calciner as a drying process unit appears effective in eliminating
the problem of incomplete reaction at the time of placing the product into drums; all known incidents
occurred where the process did not use a calciner (Enclosure, p. 1). Energy Fuels uses a calciner as the
drying process unit.
Drying Temperature
The Circular identifies a required temperature of 14720F to convert uranyl peroxide to UO3, thus
completing the process chemistry. The Ammonia process in use at the White Mesa Mill does not involve
this chemical transformation. Thus, the minimum temperature identified in the Circular does not apply to
the process chemistry in question. The calciner operating temperature range (1200 to 1400°F at the sixth
and final hearth') appears sufficient to ensure completion of the ammonia-based process chemistry.
Residual Organic Contaminants
Incomplete removal of organic solvents used in the uranium recovery process, and introduction of
lubricants into process units form the likely sources of organic contaminants in the finished process. The
White Mesa Mill recovers and reuses organic solvents, and chemical process monitoring shows that
virtually no organic solvent reaches the dryer. Additional evidence for the effectiveness of the solvent
recovery process includes the lack of loss of integrity of rubber liners in process vessels downstream of the
solvent extraction circuit. Finally, at the operating temperature of the calciner, no remaining organic
solvent would survive to exit the dryer. Lubricants inadvertently introduced into the process would suffer
the same fate.
1 Plant operators report having attempted to meet a 1600°F operating temperature in the dryer. The operators
report that temperatures above 1450°F led to damage (melting) of some dryer components.