ML22111A006

M220422B: Slides - Discussion of the Ten-Year Plan to Address Impacts of Uranium Contamination on the Navajo Nation and Lessons Learned from the Remediation of Former Uranium Mill Sites Utah (Public Meeting)

ML22111A006
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Issue date:	04/22/2022
From:	NRC/OCM
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ML22096A216	List: ML22096A222 ML22096A223 ML22096A224 ML22096A225 ML22096A226 ML22096A227 ML22096A228 ML22105A105 ML22105A107 ML22108A105 ML22108A106 ML22109A085 ML22111A006 ML22175A052 ML23104A290
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M220422B
Download: ML22111A006 (11)

Text

Lisbon Valley Uranium Mill Lessons Learned April 22, 2022 Stevie Norcross, PhD, Assistant Director

The Utah Division of Waste Management and Radiation Control, Uranium Recovery Program

• 1984 - Utah became an Agreement State and assumed regulatory responsibility for the control of radioactive materials

• 2004 - Utah was authorized by the NRC to administer the Uranium Recovery Program The Uranium Recovery Program Team Phil Goble, Program Manager Dean Henderson, Hydrogeologist Ryan Johnson, Health Physicist Heather Mickelson, Engineer Tom Rushing, Hydrogeologist Russ Topham, Engineer Waste Management and Radiation Control 2

Three Out of Eight Uranium Mills in Utah are Regulated by Utah Regulated by the State of Utah:

1. Former Lisbon Valley Mill, Rio Algom: Standby Status (Decommissioned with embankment cover and groundwater issues.)

2. Shootaring Canyon Mill, Anfield Resources Holding: Standby status

3. White Mesa Mill, Energy Fuels Resources Inc (EFRI): Active Regulated by the U.S. Department of Energy (DOE):

1. Former Salt Lake Processing Site, Vitro Chemical: Utah Cooperator Status

2. Green River, Utah Disposal Site: Utah Cooperator Status

3. Monticello, Utah Disposal and Processing Site: Decommissioned

4. Mexican Hat, Utah Disposal Site: Decommissioned

5. Former Atlas Moab Mill: Undergoing Remediation Waste Management and Radiation Control 3

Pink Pins = Utah Regulated Sites Green Pins =

DOE Regulated Sites Waste Management and Radiation Control 4

The Former Lisbon Valley Uranium Mill is Located 3.5 Miles Southwest of La Sal, Utah La Sal State Route 46 Mill Upper Tailings Lower Tailings U.S. Highway 191 Waste Management and Radiation Control 5

Lisbon Mining and Milling was Active from 1972 - 1989

• Mined from the Chinle Formation, on the downdropped, northeast side of the Lisbon Valley Fault

• Milling used an alkaline leach process

• Produced over 13 million pounds of yellowcake (U3O8)

Former Lisbon Valley Mill Waste Management and Radiation Control 6

The Lisbon Valley Uranium Mill Was Under an NRC License Until 2004

• A groundwater contamination plume was discovered in the late 1980s.

• Corrective action plan (CAP) was operated from 1990 to 2004.

Evaluation results showed no decrease in plume concentrations.

• Rio Algom submitted an application for Alternate Concentration Limits (ACLs) to the NRC based on groundwater modeling.

Modeling showed no predicted ACL exceedances for 200 years.

• ACLs made effective by the NRC in License Amendment 67 (July 6, 2004) just prior to regulatory transfer to the State of Utah.

• Upper and lower tailing impoundments covers were approved by the NRC prior to Utah regulation.

Waste Management and Radiation Control 7

Utah Regulatory Oversight Began August 16, 2004.

• Utah issued a license to the Mill on March 18, 2005.

• In 2006, License Amendment 2 required some ACLs be revised to reflect groundwater modeling.

• In 2010 - 2011 a number of wells exceeded the ACL limits.

• In 2015, Utah requested a Hydrogeological Supplemental Site Assessment (HSSA) to characterize the extent of the groundwater plume.

• Numerous additional wells were installed to assist with this characterization.

Waste Management and Radiation Control 8

Lisbon Valley Uranium Plumes

• Two plumes have been identified.

• The plumes flow west, northwest.

• The plumes have exceeded the long-term surveillance and maintenance (LTSM) boundary.

Waste Management and Radiation Control 9

Utah and the Licensee Have Continued to Investigate and Characterize the Plumes

• In 2019, a Stipulation and Consent Agreement required an updated Hydrogeological Supplemental Site Assessment Report (Phase 4), a Background Evaluation Report, an update defining the source of the plume.

• Recent findings and discussions have determined that the impoundment covers are not preventing discharge of tailings into the groundwater. Cover does not appear to be constructed according to approved design.

Cover repair, continued mitigation, and continued groundwater modeling is necessary Waste Management and Radiation Control 10

Lisbon Valley Lessons Learned

• Groundwater modeling and actual measurements go hand in hand. Models should be revised and reviewed as additional, empirical data is obtained.

• ACLs must be established based on site-specific information.

Established limits must be conservative in order to protect groundwater.

• Wells necessary to continue monitoring and ensure groundwater protection should be maintained. Do not abandon wells that may be useful for future work.

• Cover design must be built to prevent continued contamination (turn off the source). A slope is necessary to prevent water infiltration.

• Regulators must be present during cover construction to ensure the cover is constructed according to the approved design.

Waste Management and Radiation Control 11