ML23087A101

U.S. Geological Survey Triga Reactor, Annual Report Submittal in Accordance with Technical Specification 6.7.1 Rev. 00

ML23087A101
Person / Time
Site:	U.S. Geological Survey
Issue date:	03/28/2023
From:	Wallick J US Dept of Interior, Geological Survey (USGS)
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
Download: ML23087A101 (1)

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U.S. GEOLOGICAL SURVEY Rocky Mountain Region Box 25046 M.S. 974 Denver Federal Center Denver, Colorado 80225 USGS - Facility License R-113 - Docket Number 50-274 Page 1 of 1 Document Date: 2023-03-28 DATE:

Tuesday, March 28, 2023 TO:

Nuclear Regulatory Commission, Document Control Desk FROM:

Jonathan Wallick, Reactor Director/Supervisor

SUBJECT:

U.S. Geological Survey TRIGA Reactor, Docket Number 50-274, License Number R-113, Annual Report Submittal in Accordance with Technical Specification 6.7.1 Rev. 00 PURPOSE By way of this letter, the U.S. Geological Survey (USGS) is submitting the annual operating report as required by Technical Specification 6.7.1 of license number R-113, covering the period of January 1st, 2022, through December 31st, 2022.

CONTACT If you have any questions regarding this matter, please contact me at (303) 236-4726.

Sincerely, Jonathan Wallick, Reactor Director Copied to:

Shannon Mahan, Reactor Administrator, USGS Geoffrey Wertz, Project Manager, US NRC Kevin Roche, Inspector, US NRC Attachments:

(1) U. S. Geological Survey TRIGA Reactor Facility Annual Report 2022 JONATHAN WALLICK 2023.03.28 09:39:47 -06'00'

JONATHAN WALLICK l Reactor Director U. S. Geological Survey TRIGA Reactor Facility Annual Report 2022 FACILITY LICENSE R-113 - DOCKET NUMBER 50-274

U.S.G.S. TRIGA Reactor Annual Report USGS - Facility License R-113 - Docket Number 50-274 Page 1 of 18 Document Date: 2023-03-28 TABLE OF CONTENTS Table of Contents......................................................................................................................................................................... 1 Section 1: Operations Summary.................................................................................................................................................. 2 Section 2: Inadvertent Scrams, Unplanned Shutdowns, Events at Power................................................................................... 4 Section 3: Maintenance, Surveillance, and Other Incidents........................................................................................................ 6 Section 4: Facility Changes and Special Experiments Approved.................................................................................................. 9 Section 5: Radioactive Effluent Release..................................................................................................................................... 11 (a) Gases................................................................................................................................................................................ 11 (b) Liquids and Solids............................................................................................................................................................ 12 Solid, Dry Waste:.............................................................................................................................................................. 12 Liquid Waste:.................................................................................................................................................................... 12 Section 6: Environmental Surveillance...................................................................................................................................... 13 Section 7: Radiation Exposure to Personnel.............................................................................................................................. 16 Section 8: Fuel Inspections........................................................................................................................................................ 17 Section 9: Closing Remarks........................................................................................................................................................ 18

U.S.G.S. TRIGA Reactor Annual Report USGS - Facility License R-113 - Docket Number 50-274 Page 2 of 18 Document Date: 2023-03-28 SECTION 1: OPERATIONS

SUMMARY

During CY2022, the U.S. Geological Survey TRIGA Reactor Facility (GSTR) was fully operational and has seen a general return to normal operations. Efforts are underway to further stabilize operations, expand capability and capacity in cooperation with major stakeholders.

Typically, operation of this facility supports research and development by the U.S. Geological Survey, Colorado School of Mines (CSM), and a collection of other academic, commercial, and industrial collaborators. Research is usually conducted using geochronology techniques, such as argon/argon comparison and fission track analysis, but also includes student research projects and radiotracer production. Operator training and education is also a component of the GSTR program, primarily as a class conducted by CSM and supported by the reactor staff, providing hands on experience in reactor operations, engineering, and neutron activation techniques.

Additionally, tours and visits by various members of the public generally take place and have returned to pseudo-normal this calendar year owing to a reduced impact of the COVID-19 pandemic.

No NRC inspections took place this calendar year owing to other community member increased needs for support by the regulator. An inspection was scheduled for mid-January 2023.

Three personnel were given an examination by the NRC to obtain operator licenses. All three were fully successful, resulting in two new SRO-Instant operators and one RO operator. No additional personnel are in training as of now. As of December 31st, 2022, four senior operators and one reactor operator were licensed.

U.S.G.S. TRIGA Reactor Annual Report USGS - Facility License R-113 - Docket Number 50-274 Page 3 of 18 Document Date: 2023-03-28 TABLE I - General Information Experiment Authorizations Active 26 Experiments Performed 72 Samples Packages Irradiated 116 Total Samples Irradiated 2112 Energy Generated this Period (Megawatt-hours) 457.756 Total Energy Generated since Initial Criticality (Megawatt-hours) 41,148.676 Pulse Operations this Period 0

Total Pulses since Initial Criticality 298 Hours Critical this Period 625.33 Total Hours since Initial Criticality 45,111.23 Inadvertent Scrams 4

Total Scrams since Initial Criticality 1162

U.S.G.S. TRIGA Reactor Annual Report USGS - Facility License R-113 - Docket Number 50-274 Page 4 of 18 Document Date: 2023-03-28 SECTION 2: INADVERTENT SCRAMS, UNPLANNED SHUTDOWNS, EVENTS AT POWER TABLE II - Scrams, Unplanned Shutdowns, Events at Power Date Time Power Type and Cause 2022-01-06 0643 800 kW Scram #1159: NPP-1000 High Power Scram:

A high power scram was initiated by the NPP-1000 power channel. A trainee operator was in the process of establishing reactor power at 800 kW when the scram occurred. All rods inserted and the reactor was promptly shut down. Inattention to proper indications was identified as a root cause by the SRO at the console providing over instruction. Operator was counseled by the SRO on the proper indications to observe as power levels increased. Restart authorized by SRO on the basis of counsel being effective.

2022-07-27 1417 800 kW Scram #1160: DAC Watchdog Timer A DAC watchdog timer scram occurred originating in the DAC computer. The reactor was operating at a steady state 800 kW. All rods inserted and the reactor was promptly shut down.

Troubleshooting revealed no apparent cause, but it was suspected to be a time-driven fault, in that the longer the NM-1000 instrument was continuously operated (over a week in this case), the more likely it is to have communication de-synchronization with the parent computer.

Additionally, increased temperatures in the reactor bay may also have contributed to failure of the communication circuit. The instrument was shut down for several minutes and restarted, and an additional fan placed nearby to increase circulation. Restart was authorized by the SRO and saw no further timely recurrence.

2022-09-15 1321 800 kW Scram #1161: DAC Watchdog Timer A DAC watchdog timer scram occurred originating in the DAC computer. The reactor was operating at a steady state 800 kW. All rods inserted and the reactor was promptly shut down. Review of the operating power traces showed that the NP-1000 power levels were fluctuating by +/- 5% several seconds prior to the scram, but not on the analog meter indication. The NP-1000 percent power scram, which originates in the instrument, did not trip, which is analog in nature, showing that the likely issue was once again with the DAC computer itself. Testing showed the NP-1000 percent power scram and DAC watchdog scrams to be fully functional. This incident was considered spurious but also possibly influenced again by high temperatures in the reactor bay, where the DAC computer resides. Restart was authorized by the SRO and saw no further timely recurrence.

2022-11-22 0745 800 kW Scram #1162: NM-1000 Timeout Scram The NM-1000 nuclear instrument failed to communicate for a preset amount of time and caused an automatic scram of the reactor. The reactor was operating at a steady state 800 kW. All rods inserted and

U.S.G.S. TRIGA Reactor Annual Report USGS - Facility License R-113 - Docket Number 50-274 Page 5 of 18 Document Date: 2023-03-28 the reactor was promptly shut down. Similar to scram 1160, the NM-1000 once again failed to communicate after a specified delay. The instrument had been continuously operated for greater than one week, leading to the practice of resetting it on the latter of Mondays or the first operating day of the week. Despite this measure having been in practice for several months, it is still recurrent, though on a far lower frequency. Long term corrective actions consist primarily of researching and developing methods to either remove reliance on the serial communication aspect of the 1988 vintage instrument or replace it entirely with an analog equivalent. Testing could not reproduce the problem. Restart was authorized by the SRO and saw no further timely recurrence.

U.S.G.S. TRIGA Reactor Annual Report USGS - Facility License R-113 - Docket Number 50-274 Page 6 of 18 Document Date: 2023-03-28 SECTION 3: MAINTENANCE, SURVEILLANCE, AND OTHER INCIDENTS The following non-routine maintenance/surveillance activities were carried out during this period. Any reactor operation related items have been included above and are not repeated here.

TABLE III - Maintenance, Surveillance, and Other Incidents Date Time Title and Description 2022-02-03 to 2022-02-22 All Days Transient Rod Drive Refurbishment:

DISCOVERY During normal operations at 800 kW, the reactor operator noticed some difficulty in driving the transient rod up, noting in particular that it was somewhat slow to reactor and would stop moving upward at certain points in travel. The reactor was shut down at 1400 to allow for further inspection and testing.

ASSESSMENT Attempting to move the rod up and down using the controls at the console resulted in sticking at several points during upward travel. It was necessary for a person to manipulate the worm gear in the drive itself to achieve restoration of motion. The reactor supervisor, having seen this previously at his last facility, determined that the root cause was likely to be dirt, dust, grime, and overall dirtiness of the externally threaded rod and ring gear. Therefore, the decision was made to remain shut down until a full disassembly and cleaning of the mechanical portions of the transient rod drive could take place.

CORRECTIVE ACTIONS Over the course of the following two weeks, the transient rod was disconnected from the drive and the drive fully removed from the reactor bridge and placed on a table for maintenance. The drive was carefully disassembled down to the individual components and fully cleaned using a series of different chemicals and reagents. During testing of the drive motor to ensure operability and a lack of damage to the internal motor bearings, an electrical surge was introduced through the wiring of the components. This surge caused damage to multiple wires in the electrical portions of the transient rod drive, which then also required repair. All damaged wiring was fully de-soldered, replaced, and successfully tested to ensure operability. During the disassembly, multiple damaged components were found, including one defective limit switch in the upper portion of the drives range of motion, which was also successfully replaced. The drive was fully reassembled and tested successfully on the benchtop, then placed back on the reactor bridge and connected to the transient rod. Additional difficulties were found in moving the drive up and down with the added weight of the transient rod, which were then finally isolated to the exact mounting of the position indicating potentiometer attached to the worm gear drive. Binding was found to have taken place between the pinion gear and the smaller worm gear used to drive the potentiometer due to placement within thousands of an inch. This is unlikely to have been the original root cause as the potentiometer had not been moved before that point. Even further difficulty was found in reattaching the transient rod drive to the transient

U.S.G.S. TRIGA Reactor Annual Report USGS - Facility License R-113 - Docket Number 50-274 Page 7 of 18 Document Date: 2023-03-28 rod due to the excessive number of holes that have historically been drilled into the transient rods upper connecting rod. Eventually, throughout testing of the critical position versus the estimated critical position the correct holes were found and utilized to connect the drive to the rod. Full calibrations and testing took place and were found to be completely successful.

RESOLUTION After several rounds of maintenance activities on the drive and connecting rod, the transient rod was successfully repaired to full operability, demonstrating appropriate drive up and drive down speeds of approximately 35 to 40 seconds.

Final return to full operability was gained on February 22nd, 2022.

PREVENTION OF RECURRENCE In all actuality, there is no manner in which to prevent this from occurring again, as normal wear and tear and buildup of dirt, grime, and grease will occur in the exposed portions of the externally threaded cylinder of the transient rod. From review of maintenance records and historical maintenance activities at this facility, as well as other facilities that have a transient rod, this is likely the first time that this sort of activity has been performed in the 50-year history of this reactor.

Maintenance to this degree of effort should likely be undertaken every 20 to 30 years to prevent actual movements difficulties in the drive and the fact that this seems to occur on a 50-year periodicity. Therefore, the only recommended prevention of recurrence for this particular problem should be a maintenance evolution of this sort in approximately 2047. This activity will be noted as an item in the reactor database but is very unlikely to be seen in 25 years.

2021-03-21 All Day NM-1000 Electrical Damage and Repairs:

DISCOVERY During recovery on Monday, March 21st, 2022, from a power outage on Saturday, March 19th, 2022, the NM-1000 was found to be giving incorrect indications and performance at the control console.

ASSESSMENT The output of the NM-1000 was tested in the various ranges of operation using the control panel on the front of the NM-1000 enclosure. All were found to have been malfunctioning. Movement of the source from the core to the fission chamber detector attached to the NM 1000 also revealed a lack of proper response. It was then assessed at that point that the preamplifier must have suffered damage during the power outage during the previous weekend and needed replacement.

CORRECTIVE ACTIONS Several attempts were made to adjust the sensitivity of the preamplifier utilizing installed potentiometers in the instrument itself, all of which were met with failure. Additionally, attempts were made to adjust the alpha count rate corrective adjustment of the instrument by setting them at various levels, which was met with some success, however, provided a very unreliable indication of power while testing with the source. At this point, the preamplifier was fully replaced by a

U.S.G.S. TRIGA Reactor Annual Report USGS - Facility License R-113 - Docket Number 50-274 Page 8 of 18 Document Date: 2023-03-28 spare held on hand and adjusted to give approximately the same indications as pre damage response of the instrument. After replacement, a loose connection inside one of the larger connectors was found between the preamplifier and the counting circuit, which was then tightened up and performed appropriately.

Testing with and without the source showed appropriate behavior of the instrument, and adjustments of the Campbelling low and high potentiometers was also performed to account for the impact of replacement of the preamplifier on that circuit. A full power calibration was performed following this maintenance activity and showed even better response then pre damage performance.

RESOLUTION The preamplifier was successfully replaced, and associated potentiometers adjusted to gain appropriate response. Power calibration performed after the maintenance activity showed appropriate performance of the instrument. The reactor was returned to full operability following the power calibration at 1433 the same day.

PREVENTION OF RECURRENCE It is apparent that this may have been prevented from occurring in the first place by properly securing the instrument during the planned electrical work of the Denver Federal Center. The NM-1000 should have been secured and the attached uninterruptible power supply should not have been relied on to prevent a loss of power or power surge to this sensitive instrument. Several other minor items associated with the facility and offices of the reactor facility also suffered damage or demonstrated malfunction in some manner, however, did not need corrective actions performed. Moving forward, sensitive instrumentation, such as that attached to the console, should be secured prior to any planned power outage.

Additionally, periodic maintenance on the uninterruptible power supplies and replacement of their associated batteries should take place as scheduled, likely with additional testing to be performed before any planned outage.

U.S.G.S. TRIGA Reactor Annual Report USGS - Facility License R-113 - Docket Number 50-274 Page 9 of 18 Document Date: 2023-03-28 SECTION 4: FACILITY CHANGES AND SPECIAL EXPERIMENTS APPROVED Regarding 50.59 changes at the facility, initiation of work on three changes took place in calendar year 2022, while four changes were fully completed in the same period.

Completed: 2021 Experiment C-063 Review: A new experiment proposed by Dr. Sarazin of Colorado School of Mines was reviewed and approved through the 50.59 process. The experiment involves the irradiation and transfer of holmium foils, which are intended for use in medical applications. Generally, this type of target irradiation and delivery has been routinely conducted at the facility.

Completed: 2021 Moving RAM 01 Detector: The detector used by Radiation Area Monitor 01 in the reactor bay was moved from its original position on the ceiling to a lower position from the rotary specimen rack pneumatic unloading tube. This new position allows for easier access for maintenance and calibrations, as well as more appropriate and accurate indications of experiments, now indicating dose rates closer to that which personnel may experience.

Initiated and Completed: 2022 Temperature, Pressure, and Water Level Detectors: Several existing instruments on the primary cooling, secondary cooling, and transient rod air systems have been replaced with new instruments:

Primary cooling inlet pressure Primary cooling outlet pressure Secondary cooling inlet temperature Secondary cooling outlet temperature Secondary cooling inlet pressure Secondary cooling outlet pressure Transient rod air pressure indication (alarms via control console software)

Ultrasonic water level indication (alarms via control console software)

These detectors outputs were then wired to the control console to provide indication to the operator at the control console. This represents an upgrade to the system since previously, the secondary cooling system temperature readings were not available at all on the control console, and the pressure readings only existed as a binary ON/OFF indication. Additionally, the water level alarm and transient rod air pressure alarm previously provided no indication as to the actual parameters, only alarms that triggered at a mechanically adjusted set point. Using the control console software, the set points may be precisely set digitally.

Initiated and Completed: 2022 CT Sample Remover: A system capable of remotely removing high activity samples from the central thimble was installed. This system is controllable from the control room, making the level of radiation that personnel are exposed to much safer. By comparison, the method historically used to remove high activity samples from the central thimble involved opening a roof hatch and having an individual withdraw the sample over the open hatch. This motorized system provides a more precise method of handling and removed the security issue of opening the hatch, as well as mitigating the industrial and radiological safety issues.

U.S.G.S. TRIGA Reactor Annual Report USGS - Facility License R-113 - Docket Number 50-274 Page 10 of 18 Document Date: 2023-03-28 Initiated: 2022 Changing RAM 01 Detector: Changing the detector for Radiation Area Monitor 1 in the Reactor Bay from what appears to be a LND 714 to a Ludlum Model 133-3 energy-compensated GM detector.

The current detector was scavenged from a Ludlum 375 detector at some point in the facilitys history and has a hard-wired connection to a BNC cable. There is no documentation that can be located detailing any wiring diagrams, etc., of this setup. The BNC cable is also quite old and could benefit from replacement. Additionally, due to the hard-wired cable, the detector cannot easily be removed for calibration on the calibration range, so a less-rigorous in-situ calibration is typically performed. Replacing this detector will allow for calibration on the range, as well as make maintenance or replacement easier and less time-consuming in the future. This replacement process will also ensure all documentation is up to date.

U.S.G.S. TRIGA Reactor Annual Report USGS - Facility License R-113 - Docket Number 50-274 Page 11 of 18 Document Date: 2023-03-28 SECTION 5: RADIOACTIVE EFFLUENT RELEASE (A) GASES The major direct release to the environment is Argon-41 produced during normal operations. Very small amounts of other gases may be released from irradiated materials in experiments.

Releases of Argon-41 are measured directly from the effluent of the reactor bay utilizing a shielded sodium iodide detector equipped with both single channel analyzer and multichannel analyzer capabilities, and are presented below by month:

TABLE IV - Argon-41 Effluent Releases Period Average Concentration (uCi/mL)

Allowable Monthly Release (uCi/mL)

% of Monthly Allowable Release January 1.67E-08 4.8E-06 0.35%

February 1.70E-08 4.8E-06 0.35%

March 7.45E-08 4.8E-06 1.55%

April 4.50E-08 4.8E-06 0.94%

May 8.57E-10 4.8E-06 0.02%

June 2.04E-08 4.8E-06 0.42%

July 3.18E-08 4.8E-06 0.66%

August 9.69E-08 4.8E-06 2.02%

September 6.14E-08 4.8E-06 1.28%

October 1.34E-08 4.8E-06 0.28%

November 1.63E-08 4.8E-06 0.34%

December 3.36E-08 4.8E-06 0.70%

Annual Averages:

3.58E-08 4.8E-06 0.75%

Releases of Tritium are calculated using 1) the volume of water that is calculated to have evaporated from the tank in a given month, and 2) the primary water tritium concentration that was measured by an outside vendor (For Q1 and Q2 2022), and an internal measurement method (For Q3 and Q4 2022) each quarter throughout the year.

The Tritium releases are presented below, by month:

U.S.G.S. TRIGA Reactor Annual Report USGS - Facility License R-113 - Docket Number 50-274 Page 12 of 18 Document Date: 2023-03-28 TABLE V - Hydrogen-3 (Tritium) Effluent Releases Period Average Concentration (uCi/mL)

Allowable Monthly Release (uCi/mL)

% of Monthly Allowable Release January 3.48E-11 1E-07 0.03%

February 3.98E-11 1E-07 0.04%

March 4.33E-11 1E-07 0.04%

April 2.08E-11 1E-07 0.02%

May 2.71E-11 1E-07 0.03%

June 3.43E-11 1E-07 0.03%

July 3.72E-11 1E-07 0.04%

August 4.36E-11 1E-07 0.04%

September 4.29E-11 1E-07 0.04%

October 3.73E-11 1E-07 0.04%

November 4.34E-11 1E-07 0.04%

December 4.91E-11 1E-07 0.05%

Annual Averages:

3.78E-11 1E-07 0.04%

(B) LIQUIDS AND SOLIDS Liquid and solid wastes from utilization of by-product materials are disposed through a vendor contract.

Disposals to this custody are given below. It is important to note that activity values are estimated at the time of transfer. Since few shipments are being made from the federal center, decay to negligible levels occurs for all short and medium-lived radionuclides. No waste shipments were made in CY 2022.

SOLID, DRY WASTE:

No solid, dry waste transfers took place this reporting period.

LIQUID WASTE:

No liquid waste transfers took place this reporting period.

U.S.G.S. TRIGA Reactor Annual Report USGS - Facility License R-113 - Docket Number 50-274 Page 13 of 18 Document Date: 2023-03-28 SECTION 6: ENVIRONMENTAL SURVEILLANCE Calcium Sulfate/Dysprosium thermo luminescent dosimeters are in place at 11 locations around the GSTR for environmental monitoring purposes. These were provided by Mirion Technologies Global Dosimetry Services until 7/1/2022, when compounding and persistent supply and service issues led to a change in dosimetry vendors. Since 7/1/2022, dosimetry has been provided by Radiation Detection Company, which is an NVLAP-accredited dosimetry vendor and processor. The environmental dosimeters are located outside within sealed weatherproof boxes or inside the facility mounted to different walls and surfaces. The table below lists the locations.

Routine contamination surveys consisting of wipe tests and G-M surveys have shown mostly a clean facility with significant, removable contamination only in areas coming into direct contact with samples removed from the reactor, and on sample handling tools. Trash is surveyed before disposal and not disposed of unless found to be free of removable and fixed contamination.

Table VI - Locations for Environmental Dosimeters

1. Reactor Bay Exhaust

2. Vehicle Gate

3. Room 151 Door Gate

4. Cooling Tower Fence

5. Southwest Light Pole

6. West Light Pole

7. Reactor Fence

8. Basement Tunnel

9. Northwest Light Pole

10. Northeast Light Pole

11. East Light Pole

U.S.G.S. TRIGA Reactor Annual Report USGS - Facility License R-113 - Docket Number 50-274 Page 14 of 18 Document Date: 2023-03-28 Table VII - Environmental Dosimetry Data Average Total Deep Dose Exposures in mrem (Including Control Background)

Location Quarter Annual Prior Year Difference 2022 Q1*

2022 Q2*

2022 Q3 2022 Q4

1. Reactor Bay Exhaust 42 23 11 16 92 151

-59

2. Vehicle Gate 17 0

0 0

17 82

-65

3. Room 151 Door Gate 81 33 20 58 193 294

-101

4. Cooling Tower Fence 1

0 0

0 1

32

-31

5. Southwest Light Pole 3

0 0

0 3

35

-32

6. West Light Pole 2

0 0

0 2

33

-31

7. Reactor Fence 36 17 0

28 82 158

-76

8. Basement Tunnel 76 50 27 103 256 285

-29

9. Northwest Light Pole 0

0 0

0 0

27

-27

10. Northeast Light Pole 0

0 0

0 0

26

-26

11. East Light Pole 0

0 0

0 0

29

-29 Notes:

1. Above totals have the background subtracted. Q1 and Q2 2022 TLDs were supplied and analyzed by Mirion Technologies, NVLAP accredited dosimetry vendor. Q3 and Q4 TLDs were supplied and analyzed by Radiation Detection Company, NVLAP accredited dosimetry vendor.

2. Due to the ongoing COVID-19 pandemic, Mirion Technologies has experienced significant delays in shipping new TLD personnel and environmental badges to the GSTR. As a result:

a. 4th Quarter 2021 badges monitored from 2021-10-01 to 2022-02-14 and were adjusted to reflect the portion of the monitoring period in CY22, approximately 32.8% of the vendor reported dose.

This portion of the dose was then added to the nominal Q1 2022 Mirion badges, which recorded dose from February 14 to April 7, 2022, to calculate the overall Q1 2022 dose.

b. 2nd Quarter badges from Mirion monitored from 2022-04-07 to 2022-08-11; this dose was then adjusted to reflect the potion of the monitoring period in Q2 2022 (04-07 to 07-01),

approximately 66.67% of the vendor reported dose.

c. Radiation Detection Company became the GSTR dosimetry vendor as of 07-01-2022. There have been no issues with receiving badges on time since then. 2022 Q3 and 2022 Q4 doses thus required no special adjustment.

d. 2021 Q4 badges did not have background adjusted, since the control badges were lost. Instead, a representative background provided by Mirion was used to adjust the dose manually.

U.S.G.S. TRIGA Reactor Annual Report USGS - Facility License R-113 - Docket Number 50-274 Page 15 of 18 Document Date: 2023-03-28 Discussion Raw data is presented here, along with a comparison to the prior year. Locations near or inside the facility are usually the highest; by contrast, remote locations (such as the light pole series) are the lowest. Data for this year reflect several points of interest:

Location 1 tends to have higher doses when high-activity volatile samples are processed in the fume hood, since some of the volatile material will be captured in the nearby HEPA filters for that hood.

Indeed, Q1 2022 saw several very high-activity samples processed there.

Locations 3 and 7 are positioned on the west fence of the facility. Several sources of radiation are present near these badges: 1) a dry storage tank in Room 151, which contains a previously installed rotary specimen rack, which has a substantial amount of Cobalt-60, 2) high-activity sample transfers in the fume hood in Room 151 can temporarily elevate the dose rate, and 3) reactor operation will marginally elevate the dose rate to about double the background dose rate.

Location 8, in the basement, is opposite a wall for the main radioactive waste storage area. This area has a very low occupancy factor, and the waste is intended to be shipped out for disposal in CY 2023.

Exposure estimated to a single individual in an uncontrolled area at this facility is minimal. Location 1 is on the facility roof, so a member of the public would not have reason to be up there, and maintenance activities are infrequent and thus result in a very low occupancy factor.

Locations 3 and 7 are physically closest to the facilitys walls and highest source of exposure, which was the logic in choosing those locations. The Denver Federal Center itself has a limited public occupancy, as it is only open to the public from 0600-1800 during the week. So, the possible maximum exposure to any one point that is accessible to the layperson is approximately 36%, not accounting for holidays nor the fact that any person occupying space near the facility would be challenged and asked to leave if they had no just cause.

U.S.G.S. TRIGA Reactor Annual Report USGS - Facility License R-113 - Docket Number 50-274 Page 16 of 18 Document Date: 2023-03-28 SECTION 7: RADIATION EXPOSURE TO PERSONNEL The GSTR issues TLD badges to reactor staff and volunteers of the facility only. Finger dosimetry (TLD) rings are also issued to all badged personnel, as there is a strong likelihood of regularly handling radioactive sources.

Before 7/1/2022, TLDs were read monthly by Mirion Technologies; after 7/1/2022, TLDs are processed by Radiation Detection Company. Since Mirion was not able to supply the GSTR personnel badges for January 2022, this reporting period starts 2/1/2022, with January 2022 monitoring being wrapped into the 2021 Annual Report. Reporting categories are deep, eye, shallow, and extremity. Other individuals visiting or intermittently working in the facility were issued electronic dosimeters which are documented in the facilitys Visitor Log and have no appreciable exposures.

TABLE VIII Personnel Exposure (mrem) 2022-02-01 to 2022-01-31 Employee Code Whole Body Ring Deep Eye Shallow Shallow CF0707 465 469 476 826 JJ0722 22 22 22 0

VL0722 25 25 24 61 CM0715 231 312 291 425 JW0420 308 312 291 717 MB1021 46 46 48 44 TB282 28 30 40 0

BO290 15 15 19 32 RM291 2

2 2

7 Total 1142 1233 1213 2112

1. Above totals have the background subtracted. Before 7/1/2022, TLDs were processed by Mirion Technologies. After 7/1/2022, TLDs were processed by Radiation Detection Company.

2. Due to the ongoing COVID-19 pandemic, Mirion Technologies has experienced significant delays in shipping new TLD personnel and environmental badges to the GSTR. As a result:

a. Badges were not received for January 2022. Thus, this table reports doses starting 2/1/2022.

January 2022.

3. Although neutron dose is monitored, no person experienced any neutron dose during any monitoring period.

Personnel exposures continue to be very low at this facility in keeping with ALARA efforts.

U.S.G.S. TRIGA Reactor Annual Report USGS - Facility License R-113 - Docket Number 50-274 Page 17 of 18 Document Date: 2023-03-28 SECTION 8: FUEL INSPECTIONS No fuel inspections took place this reporting period.

U.S.G.S. TRIGA Reactor Annual Report USGS - Facility License R-113 - Docket Number 50-274 Page 18 of 18 Document Date: 2023-03-28 SECTION 9: CLOSING REMARKS This has been a highly successful year for the GSTR facility, though, not without its challenges. As can be seen above, aging management presents significant maintenance requirements, and is being given due attention as a result. Significant progress has been achieved in the multiple improvements and initiatives underway at the facility, as mentioned in last years report:

Unnecessary storage space has been fully decommissioned and handed back to GSA in early CY2023, maintaining the desired footprint for the facility.

Renovation and establishment of an analytics laboratory, equipped for neutron activation analysis and inductively coupled plasma optical emission spectroscopy, is moving along in leaps and bounds. The space was completely abated for asbestos, with several construction activities progressing nicely.

Spades of laboratory equipment have been obtained and are awaiting installation.

July marked the first staff hire since Center Director Wallick took station in April of 2020. The position established was internally termed Chief of Operations and Maintenance and filled by Christopher Farwell, who was already a member of the team. Backfilling his previous position is underway and set for filling sometime in mid-year 2023. Following that action will be an analyst position for the new laboratory late in 2023.

Once again, as no new personnel have started, core analyses and designs have been kept as lower priorities, but with a positive outlook on obtaining additional personnel, these will pick up again in the near future.

The facility continues forward with the strategic plan to maintain and improve relevance, capability, and capacity, as all research and test reactors tend to struggle with. Partnerships with our stakeholders continue to broaden and improve, securing the scientific and commercial impacts of the facility.