DRC-2025-002240

299 South Main Street, Suite 1700 ▪ Salt Lake City, Utah 84111
[phone] ▪ Fax: [phone] ▪ www.energysolutions.com
July 7, 2025 CD-2025-139
Mr. Doug Hansen, Director
Division of Waste Management and Radiation Control
P.O. Box 144880
Salt Lake City, UT 84114-4880
Subject: Radioactive Material License (RML) UT2300249: Notification to Discontinue
Gamma Spike Service Provider
Dear Mr. Hansen:
EnergySolutions hereby submits a notification to discontinue additional gamma spike
services provided by Landauer. In the first quarter of 2020, EnergySolutions contracted
with Landauer to provide additional gamma spike data to compare results to those
provided by our regular gamma dosimetry service provider, Mirion Technologies, based
on the premise that Mirion was not able to consistently meet the required relative mean
difference (RMD) performance criterion of ±10%. After collection of five years of data,
it has become clear that Landauer is also not able to meet a ±10% RMD criterion and has
achieved less accuracy than Miron.
Table 1 provides all gamma dosimetry spike data received to date when both providers
were used. While Mirion results are generally biased low, on average, the data meet the
±10% performance criterion. Landauer results are generally biased high, and on average,
do not meet the ±10% performance criteria. Results from both providers validate
EnergySolutions’ request to modify the Environmental Monitoring Plan (EMP) to relax
the performance criterion (e.g., ±20%). The current performance criteria cannot be met
for individual dosimeters. Also, the regulatory basis for the ±10% RMD criterion is
unclear, but based on operational experience, it does not appear to be a requirement the
gamma spike industry can routinely meet. The EMP Part 6.4 and 7.0 do not require the
use of two separate providers; therefore, the use of Landauer dosimeters will be
discontinued as of the first quarter of 2026 and only gamma spike data from Mirion will
be provided beginning with the 2026 1st Semi-Annual Environmental Monitoring Report.
Should you have any questions regarding this submission please feel free to contact me at
[phone].
Sincerely,
Mathew R. Schon
Manager, Groundwater and Environmental Program
Mr. Doug Hansen
July 7, 2025
CD-2025-139
Page 2 of 3
I certify under penalty of law that this document and all attachments were prepared under my direction or supervision in accordance
with a system designed to assure that qualified personnel properly gather and evaluate the information submitted. Based on my inquiry
of the person or persons who manage the system, or those persons directly responsible for gathering the information, the information
submitted is, to the best of my knowledge and belief, true, accurate, and complete. I am aware that there are significant penalties for
submitting false information, including the possibility of fine and imprisonment for knowing violations.
TABLE 1
Mirion Landauer
Quarter Spike Result RMD Spike Result RMD
(mrem)(%)(mrem)(%)
94 -5.8%113 12.5%
91 -9.3%117 17.3%
88 -12.0%113 12.5%
92 -8.0%117 17.3%
87 -13.0%120 20.0%
89 -11.0%108 7.8%
95 -5.0%113 13.4%
96 -4.0%114 13.6%
87 -13.0%99 -1.2%
90 -9.7%104 4.4%
84 -16.3%119 19.4%
90 -10.3%107 7.2%
100 0.0%113 13.3%
88 -12.3%115 14.8%
95 -5.3%111 11.1%
91 -8.7%102 2.1%
97 -3.3%113 12.7%
93 -7.3%106 5.5%
91 -9.3%110 10.3%
94 -6.0%106 5.9%
107 7.3%119 18.6%
100 0.3%112 12.3%
102 2.3%113 12.5%
97 -2.7%115 15.0%
105 5.0%128 27.6%
102 2.0%123 23.2%
103 3.0%107 6.5%
104 4.3%109 8.6%
103 3.3%108 8.2%
101 1.3%111 10.8%
96 -4.3%106 5.6%
109 8.7%101 1.0%
106 6.3%112 11.5%
101 1.0%116 15.8%
102 2.0%83 -17.2%
105 5.0%93 -6.9%
95 -5.0%113 13.4%
94 -6.0%117 16.6%
Minimum 84 -16.3%83 -17.2%
Maximum 109 8.7%128 27.6%
Average 96 -3.6%111 10.6%
Percent
Compliant
24Q4
COMPARISON OF MIRION AND LANDAUER GAMMA SPIKE DATA
82%34%
23Q2
23Q3
23Q4
24Q1
24Q2
24Q3
21Q4
22Q1
22Q2
22Q3
22Q4
23Q1
20Q1
20Q3
20Q4
21Q1
21Q2
21Q3