ML25084A330

North Carolina State Pulstar Reactor Facility 2024 Annual Operating Report

ML25084A330
Person / Time
Site:	North Carolina State University
Issue date:	03/24/2024
From:	Hawari A North Carolina State University
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
Download: ML25084A330 (1)

Text

Nuclear Reactor Program Department of Nuclear Engineering nrp.ne.ncsu.edu Campus Box 7909 2500 Stinson Drive Raleigh, NC 27695-7909 919.515.7294 (voice) 919.513.1276 (fax) 24 March 2024 Document Control Desk US Nuclear Regulatory Commission 11555 Rockville Pike Rockville, MD 20852 Re:

Annual Report for 2024 License No. R-120 Docket No. 50-297 In accordance with Technical Specification 6.7.4, the annual operating report for the North Carolina State PULSTAR Reactor facility is attached.

If you have any questions regarding this correspondence or require additional information, please contact Austin Wells, Manager of Engineering and Operations at 919-515-3347, or via email at ajwells2@ncsu.edu.

I declare under penalty of perjury that the forgoing is true and correct. Executed on 24 March 2024.

Ayman I. Hawari, Ph. D.,

Director, Nuclear Reactor Program North Carolina State University

Enclosures:

Annual Operating Report for 2024 Attachment A: PULSTAR Reactor Environmental Radiation Surveillance Report 2024 Ay A man I. Hawari, Ph. D.,

Annual Operating Report for 2024

1 NORTH CAROLINA STATE UNIVERSITY DEPARTMENT OF NUCLEAR ENGINEERING PULSTAR REACTOR ANNUAL REPORT DOCKET NUMBER 50-297 For the Period: 01 January 2024 - 31 December 2024 The following annual report for 2024 is submitted in accordance with Section 6.7.4 of the North Carolina State University PULSTAR Reactor Technical Specifications:

6.7.4.a Brief Summary:

Reactor operations have been routine during this reporting period.

i Operating experience including a summary of experiments performed.

The reactor facility had a total of 2569.7 utilization hours in 2024. The following is a brief summary of the types of experiments performed, including for teaching laboratories, courses, research and service:

x 1/M Approach to criticality x

Control rod worth measurements x

Reactivity parameter measurements x

Core thermal power and coolant temperature measurements x

Axial power and peaking factor measurements (flux mapping) x Reactor power determination using photodiode arrays x

Positron annihilation spectroscopy measurements x

Neutron diffraction measurements x

Neutron transmission measurements x

Neutron flux measurements x

Neutron detector testing and certification x

Neutron radiographic imaging x

Isotope production x

Neutron activation analysis measurements x

Electronic component irradiation testing x

Molten salt irradiation facility experimental testing x

Fiber Optical Imaging System Irradiation x

Semiconductor Material Irradiation

2 ii Changes in Performance Characteristics Related to Reactor Safety:

None iii Results of Surveillance, Tests, and Inspections:

The reactor surveillance program has monitored the following trends in reactor systems performance during this reporting period:

An unaccounted loss of primary water that began in 2015 continued through 2024. The performance of the temporary patch box installed in 2023 was monitored and used to verify that the source has been identified.

Efforts toward a final repair continue. The concentration of radionuclides detected in reactor coolant continues to meet regulatory limits for release to unrestricted areas (10 CFR 20 Appendix B Table 2).

The non-safety reactor power monitoring N-16 Channel failed during operations. All appropriate operator responses were taken, but since channel failure occurred during reactor operations above 500 kW, a TS violation was reported to the NRC. The channel was thoroughly inspected, tested, repaired, and returned to service. An update to TS Sections 1 and 3 is being pursued with the NRC to allow credit for operator action in responding to and correcting abnormal channel behavior, in conformance with ANSI 15.1-2007.

No other significant or unexpected trends in reactor system performance have been identified during this reporting period.

The Reactor Safety and Audit Committee (RSAC) performed its annual audit for the facility and determined that all phases of operation and supporting documents were in compliance.

6.7.4.b Energy Output and Critical Hours:

Total Energy Output in 2024:

52.1 Megawattdays Critical hours in 2024:

1,487.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> Cumulative Total Energy Output Since Initial Criticality:

2,305.9 Megawattdays 6.7.4.c Number of Emergency and Unscheduled Shutdowns:

Emergency Shutdowns - NONE Unscheduled Shutdowns - Five 5-MARCH-2024 SCRAM as a result of the loss of commercial power in Burlington Engineering Labs. The reactor system loads were automatically transferred to back-up power until commercial power was restored. A complete set of pre-operational checks was performed following restoral of commercial power and prior to resuming reactor operations.

22-May-2024 Shutdown due to immediate operator action in response to indication of low natural gas pressure. The natural gas service to Burlington Engineering Labs (BEL) was interrupted due to a line break caused by construction near the building. Upon restoration of natural gas pressure and service to BEL, a complete set of pre-operational checks was performed prior to resuming reactor operations.

3 28-JUNE-2024 Shutdown due to immediate operator action in response to abnormal channel behavior of the N-16 power measuring channel. The operator observed a sudden drop in indicated reactor power on the N-16 channel which was not reflected on any of the other power monitors. The channel was determined to be incapable of performing its intended function and deemed inoperable. Because the channel is required by TS 3.4(a) to be operable during reactor operations in excess of 500 kW, the event was classified as a TS violation and reported to the NRC.

Subsequent investigation determined that degradation of the detector-cable connection as a result of surface oxidation had rendered the channel sensitive to mechanical disturbance. The affected connectors were thoroughly cleaned and desiccants were installed to mitigate future oxidation. All components of the channel were extensively tested individually, and comprehensive performance tests and checks were performed on the reassembled channel prior to reintroduction to service. Reactor operations were limited to 400 kW until the channel was returned to service and verified to be operating as intended.

As required by TS, a report was issued to the NRC on 2 July 2024 (Report for Event Number 57196 Technical Specification Violation ML24193A107).

27-AUG-2024 Shutdown due to immediate operator action in response to process radiation monitor alarms and subsequent evacuation initiation of the reactor bay. The radiation recorder trace indicated elevated readings on multiple radiation monitors including trends of a puff release on the effluent monitors. The process monitors reached their maximum readings within the first minute of evacuation initiation and then trended downward to normal levels.

Subsequent investigation determined that Ar-41 produced inside the pneumatic transfer system had been allowed to escape following temporary misalignment of a gas isolation block at the pool top. Grab air samples, particulate, and CAM filters confirmed this assumption due to the absence of fission and activation products. The calculated average Ar-41 AEC over the evacuation period was about 100 times the AEC during normal operations and about 1% of the EP-4 EAL. The dose received at the most conservative public location during the period was estimated to be 0.007 mrem. Combined with the effluent releases for the entire month, doses to the public were well within the 10 mrem dose constraint. Resumption of reactor operations was approved following the conclusion of the above investigation.

15-OCT-2024 Low Flow SCRAM due to abnormally high primary coolant flow rate. Fluctuations in the measured primary flow rate caused measured flow to momentarily exceed the high flow rate trip setpoint. The high flow trip is not required by TS and is only implemented to identify channel inoperability due to a transmitter high failure. Average primary coolant flow was verified to be slightly above the nominal 500 gpm, which exacerbated by channel fluctuations resulted in the trip. The primary pump VFD was adjusted to achieve the nominal flow rate and reactor operations were resumed. Primary coolant flow was closely monitored to verify channel performance and quantify fluctuations in the indication.

4 6.7.4.d Corrective and Preventative Maintenance:

Preventative maintenance, tests and calibrations are scheduled, performed and tracked utilizing the PULSTAR Surveillance File System. Each major component of the Reactor Safety System defined in Section 3.3, and all surveillance required by Section 4 of the Technical Specifications are monitored by this file system to ensure that maintenance and calibrations are performed in a timely manner. All historical data relating to those components, in addition to many other sub-systems, are maintained in these files. Any reactor equipment or components requiring corrective or preventative maintenance are tracked in the Maintenance Log (ML) file. Maintenance Log items tracked during 2024 are listed below.

ML#0894 PS-1-10-7A - RTD Hx Pri. Hot (T5) - Temperature probe lead wires damaged during reinstallation during semiannual maintenance outage on 11 March 2024. The wires were repaired, the T5 temperature measuring channel was calibrated, and tested satisfactory prior to resuming reactor operations.

ML#0895 PS-4-01 Safety No. 1 In-Line Drive - The control rod position indication was observed to be unresponsive during performance of the pre-operation checklist on 22 March 2024. The CRDM motor package encoder output shaft was found to have seized due to shim impingement. The motor-encoder gearset was replaced with a spare and the drive assembly was returned to service following performance of drive time measurements.

ML#0896 PS-7-01 Pneumatic Transfer Photogate Sensor - Spurious Pneumatic Sample in Reactor annunciators signals were generated by foot traffic around the pneumatic system block and switch assembly at the reactor pool top beginning on 1 April 2024. The cause was determined to be vibrations causing the photogate to erroneously report transit of a pneumatic rabbit. The photogate mounting bracket was realigned satisfactorily and a replacement of the obsolete sensor with modern equivalents is being pursued as part of upgrades to the pneumatic transfer system.

ML#0897 PS-3-02-5A - Secondary Makeup Solenoid (S-22) - The cooling tower basis water level was observed to be abnormally low during operations on 1 April 2024. The cause was determined to be loss of secondary coolant makeup due to makeup solenoid S-22 stalling closed. Secondary makeup was performed using the manual bypass while S-22 was isolated, inspected, and cleaned prior to being returned to service. A note was added to the periodic maintenance schedule to disassemble, clean, and lubricate the solenoid.

ML#0898 PS-1-05-3A - Safety Channel UIC Housing - A stream of small bubbles was reported from the Safety Power Channel UIC housing on 21 June 2024. The nitrogen detector purge was verified to be +8.4 psig vs ambient pressure at the submerged depth and no abnormal behavior has been observed on the Safety Power Channel. These bubbles are consistent with past observations of the eventual degradation of the o-ring seals on detector housings. Removal, inspection, and replacement of the detector housing o-rings is planned for (was performed during) the first semiannual maintenance outage in 2025.

ML#0899 PS-1-14 Power Conditioning Transformer - The control console UPS discharged during the performance of the pre-operation checklist on 25 June 2024. The cause was determined to be failure of the conditioning transformer used to supply power to the UPS and other equipment in the control room. The transformer was replaced with a spare and a complete pre-operation checklist was completed prior to reactor operations.

ML#0900 PS-1-08-4A - N-16 Channel - The N-16 Channel exhibited abnormal behavior during reactor operations on 27 June 2024, prompting an unscheduled shutdown. The system was thoroughly tested in-situ and on a benchtop and its components were tested individually in-situ and on the

5 benchtop. The behavior was replicated and determined to be caused by partial oxidation of the HV connection at the detector. The affected and proximal connectors were thoroughly cleaned and the frequency of desiccant replacement was increased to mitigate future oxidation of the detector components. The system was calibrated and all surveillance procedures were performed satisfactory prior to returning to operations at powers above 500 kW.

ML#0901 PS-3-03 Primary Resin Change (Demin) - Primary resin and the pre/post filters in the primary demineralizer loop were proactively replaced on 8 July 2024.

6.7.4.e Changes in Facility, Procedures, Tests, and Experiments:

Design changes to the facility, procedure changes, changes in tests and experiments, and other changes are tracked utilizing a Control Number (CN) indexing system. Changes tracked during 2024 are listed below.

Facility Changes Design changes to the reactor facility are reviewed to determine whether or not a 10 CFR Part 50.59 evaluation is required. Evaluations were performed for all design changes.

No new test or experiment reviews were performed during this period.

Test and Experiments Tests and experiments are reviewed to determine whether or not a 10 CFR Part 50.59 evaluation is required.

No new test or experiment reviews were performed during this period.

Document Changes Procedure changes are reviewed to determine whether or not a 10 CFR Part 50.59 evaluation is required.

Based on the screening reviews performed, none of the changes listed below required a full 10 CFR 50.59 evaluation.

CN#886 EP-1 Emergency Plan Activation and Response - Attachment 8 of this procedure was updated to reflect changes to personnel and associated contact information.

CN#887 EP-6 Emergency Preparedness: Training, Drills, and Inventory - Attachments 4 & 5 of this procedure were updated to reflect changes to the storage location of SCBA respirators available to the emergency team CN#888 OP-104: Reactor Experiments - Procedure updated to implement changes to the requirements for fueled experiments approved under amendment 20 to the Technical Specifications. This change also revised the procedural definition of fueled experiment to conform to the definition provided in TS.

CN#889 EP-1 Emergency Plan Activation and Response - Attachment 8 of this procedure was updated to reflect changes to personnel and associated contact information.

CN#890 EP-4 Emergency Classification - Attachment 1 of this procedure was updated to include EAL criteria for airborne release which take credit for exhaust dilution while operating in normal ventilation mode.

CN#893 XP-412: Methane System Procedures - Procedure was adopted into facility experiment procedure set in preparation for operation of methane cryogen systems as part of the Ultra Cold Neutron Source facility.

6 Other Changes License Renewal and Amendments:

NC State continued to update the TS and SAR in support of the ongoing license renewal process. No new license amendments were requested in 2024.

6.7.4.f Radioactive Effluent:

Liquid Waste (summarized by quarters)

i.

Radioactivity Released During the Reporting Period:

Releases to the sanitary sewer are given below:

Period (1)

(2)

(3)

(4)1 (5) 2024 Number of Batches Total PCi Total Volume Liters Diluent Liters Tritium PCi 01 JAN - 31 MAR 1

47 3,220 16,400 47 01 APR - 30 JUN 3

272 9,460 7,110 271 01 JUL - 30 SEP 8

778 25,600 0

777 01 OCT - 31 DEC 4

325 12,500 0

324 2024 1416 PCi of tritium was released during this year.

2024 1421 PCi of total activity was released during this year.

1Based on gross beta activity only. Tritium did not require further dilution.

ii.

Identification of Fission and Activation Products:

The gross beta-gamma activity of the batches in (i) above were less than 2u10-5 /ŽŽ

of these batches indicated low levels of typical corrosion and activation products. No fission products were detected.

iii.

Disposition of Liquid Effluent not Releasable to Sanitary Sewer System:

All liquid effluent met the requirements of 10 CFR Part 20 for release to the sanitary sewer.

iv.

Releases to Unrestricted Areas:

In 2024 an unaccounted loss of water from the reactor coolant system (RCS) occurred. The RCS water loss is measured every work day and occurred at variable rates over the year. RCS water was not observed in surface locations or storm sewer locations outside the reactor building. Therefore the unaccounted RCS water was assumed to be continuously released to grounds beneath the surface on the reactor site at the measured RCS loss rates over the year. Reactor coolant activity and volume assumed to be released to unrestricted areas are given below for 2024:

Period in 2024 Total PCi Tritium Ci Volume Liters 01 JAN - 31 MAR 4,347 4,340 21,118 1 APR - 30 JUN 3,939 3,930 19,079

7 1 JUL - 30 SEP 4,365 4,356 21,918 1 OCT - 31 DEC 4,611 4,605 22,048 CALENDAR YEAR TOTAL 17,262 17,231 84,163 The concentration of radionuclides detected in the reactor coolant met regulatory limits for release to unrestricted areas (10 CFR 20 Appendix B Table 2). Detected radionuclides in reactor coolant were tritium and activation products. Fission products were not detected. No tritium or activation products were detected in environmental samples (refer to Section 6.7.4.i below).

Gaseous Waste (summarized monthly)

i.

Radioactivity Discharged During the Reporting Period (in Curies) for:

(1)

Gases:

Year Month Total Time Hours Curies 2024 JANUARY 744 0.603 FEBRUARY 696 0.706 MARCH 744 0.478 APRIL 720 0.493 MAY 744 0.220 JUNE 720 0.297 JULY 744 0.146 AUGUST 744 0.444 SEPTEMBER 720 0.238 OCTOBER 744 0.368 NOVEMBER 720 0.376 DECEMBER 744 0.320 TOTAL 8784 4.689 (2)

Particulates with a half-life of greater than eight days:

Particulate filters from the Stack Particulate Monitoring Channel were analyzed upon removal. There was no particulate activity with a half-life greater than 8 days detected.

ii.

Gases and Particulates Discharged During the Reporting Period:

(1)

Gases:

Total activity of Argon-41 released was 4.689 Curies in 2024.

8 The yearly average concentration of Argon-41 released from the PULSTAR reactor facility exhaust stack in 2024 was 2.27u10-8 ŽŽ for the year were performed using methods given in the Final Safety Analysis Report and gave results less than the 10 CFR Part 20 constraint level of 10 mrem. These results are consistent with environmental monitoring data given in Attachment A.

(2)

Particulates:

Refer to gaseous waste i.(2) above. No activation or fission products were detected.

Solid Waste from Reactor

i.

Total Volume of Solid Waste Packaged Total volume of solid waste was 21.5 ft3.

ii.

Total Activity Involved Total activity for solid waste was 3.04 mCi. (0.0729 mCi +1.5 mCi + 1.47mCi) iii.

Dates of shipments and disposal Transfer of solid radioactive waste to the university broad scope radioactive materials license was made in September and December 2024. The University Environmental Health and Safety Center arranges disposal of hazardous wastes.

6.7.4.g Personnel Radiation Exposure Report:

Thirty-seven individuals were monitored for external radiation dose during the reporting period. Internal dose monitoring was not required for any individual. Collective deep dose-equivalent was 3.589 person-rem. Individual deep dose-equivalent ranged from 0.000 rem to 0.778 rem with an average of 0.094 rem.

Three individuals were above 0.250 rem.

6.7.4.h Summary of Radiation and Contamination Surveys Within the Facility:

Radiation and contamination surveys performed within the facility indicated that:

x Radiation in the majority of areas was 5 mrem/h or less.

x Radiation in the remaining areas was higher due to reactor operations.

x Contamination in most areas was not detectable. When contamination was detected, the area or item was confined or decontaminated.

6.7.4.i Description of Environmental Surveys Outside of the Facility:

Refer to Attachment A for results of environmental sampling and analysis.

Radiation surveys performed in unrestricted areas near the reactor facility indicated that:

x Radiation was at background levels for most areas (background is approximately 20 rem/h).

x Contamination was not detectable.

9 x

Net radiation readings ranged from 0 to 30 rem/h while the reactor was operating at power.

Radiation was at background levels in all routinely occupied spaces.

x Water samples from Rocky Branch Creek and on-site ground water monitoring wells were analyzed in 2024 for tritium, gross beta activity, gross alpha activity, and gamma radiation. All sample results were consistent with background radioactivity. Environmental monitoring of Rocky Branch Creek and groundwater is routinely performed in accordance with facility procedures.

ATTACHMENT A:

PULSTAR Reactor Environmental Radiation Surveillance Report 2024

ATTACHMENT A PULSTAR REACTOR ENVIRONMENTAL RADIATION SURVEILLANCE REPORT FOR THE PERIOD JANUARY 1, 2024 - DECEMBER 31, 2024 NORTH CAROLINA STATE UNIVERSITY ENVIRONMENTAL HEALTH AND SAFETY CENTER RADIATION SAFETY by Alyson Prior, Environmental Health Physicist Scott Lassell, Radiation Safety Officer

TABLE OF CONTENTS PAGE NO.

1.

INTRODUCTION 3

Table 1 Environmental Monitoring Programs for the PULSTAR Reactor 4

2.

AIR MONITORING 5

Table 2.1 Location of Air Monitoring Stations 5

Table 2.2 Airborne Gross Beta Activities 6

Table 2.3 Airborne Gamma Activities (LLD Values) 6 Table 2.4 Regulatory Limits, Alert Levels and Background Levels 7

for Airborne Radioactivity

3.

MILK Table 3.1 I-131 in Cows Milk 7

4.

SURFACE WATER Table 4.1 Gross Alpha and Beta Activity in Surface Water 8

Table 4.2 LLD Values for Gamma Emitters in Surface Water 9

Table 4.3 Tritium Activity in Surface Water 10

5.

VEGETATION Table 5.1 Gross Beta Activity in Campus Vegetation 11 Table 5.2 LLD Values for Gamma Emitters in Vegetation 11

6.

OPTICALLY STIMULATED DOSIMETERS 12 Table 6.1 Environmental Dosimeter Doses 12

7.

QUALITY CONTROL INTERCOMPARISON PROGRAM 13 Tables 7.1 & 7.2 14 -15

8.

CONCLUSIONS 16 2

1.

INTRODUCTION The Environmental Radiation Surveillance Program exists to provide routine measurements of the university environment surrounding the PULSTAR Reactor.

The specific objectives of this program include:

1)

Providing information that assesses the adequacy of the protection of the university community and the public-at-large;

2)

Meeting requirements of regulatory agencies;

3)

Verifying radionuclide containment in the reactor facility;

4)

Meeting legal liability obligations; and

5)

Providing public assurance and acceptance.

Table 1 below details the environmental monitoring and sampling program for the PULSTAR reactor facility. Sections of this report detail the results for samples collected and analyzed to meet the programmatic and regulatory requirements as given in the table.

3

Table 1 Environmental Monitoring Programs for the PULSTAR Reactor at North Carolina State University Sample Activity Measured Conducted By Current Frequency Basis For Measurement Stack Gases Gross Gamma N.E.

Continuous 10 CFR 20 T.S. 6.7.4 Stack Particles Gross Beta Gamma N.E.

N.E.

Monthly 10 CFR 20 T.S. 6.7.4 Water from Reactor Facility Gross Beta Gamma Tritium N.E.

N.E.

N.E.

Prior to Discharge

(~ Monthly) 10 CFR 20 T.S. 6.7.4 City of Raleigh Ordinance Air Particles at 4 Campus Stations*

Gross Beta Gamma RSD RSD Quarterly Quarterly 10 CFR 20 10 CFR 20 Air Dose at 7 Campus Stations +

OSD Dosimeter RSD Quarterly 10 CFR 20 Surface Water Rocky Branch Creek Gross Alpha/Beta Gamma Tritium RSD RSD RSD Quarterly Quarterly Quarterly NCSU NCSU 10 CFR 20 Vegetation NCSU Campus Gross Beta Gamma RSD RSD Every Other Year NCSU NCSU Milk Local Dairy I-131 RSD Every Other Year NCSU Abbreviations Used in Table:

N.E. = Nuclear Engineering/Reactor Facility; RSD = Radiation Safety Division.

• These 4 stations include:

Withers, Lampe, Polk and the Environmental Health & Safety Center (EHS).

+These 7 stations include: The PULSTAR Reactor, the 4 air sampling stations, North Hall and an Area 1 control station at the Environmental Health and Safety Center.

4

2.

AIR MONITORING Air monitoring is performed continuously for one week during each of four calendar quarters during the year at the locations given in Table 2.1. The data in Table 2.2 represents gross beta activity levels measured during the year. The highest gross beta activity observed was 21.7 fCi/cubic meter at the Withers station during the week of 10/9/24 to 10/18/24. This level of activity was analyzed through gamma spectroscopy and found to be primarily natural Radon products. The annual campus average value was 16.0 fCi/cubic meter which is consistent with previous years. The LLD value for beta activity is 1.5 fCi/cubic meter.

Table 2.3 lists LLD values for several gamma emitters which would be indicative of fission product activity. No gamma activity due to any of these radionuclides was detected.

Table 2.4 lists regulatory limits, alert levels, and average background levels for airborne radioactivity.

TABLE 2.1 LOCATION OF AIR MONITORING STATIONS SITE DIRECTION 1 DISTANCE 2 ELEVATION 3 (meters)

(meters)

LAMPE

• SOUTHEAST 90

-8 WITHERS NORTHEAST 82

-6 EHS CENTER WEST 1230

-3 NORTH HALL **

NORTHEAST 402

-4 POLK HALL WEST 100 -7 1 DIRECTION - DIRECTION FROM REACTOR STACK 2 DISTANCE - DISTANCE FROM REACTOR STACK 3 ELEVATION - ELEVATION RELATIVE TO THE TOP OF THE REACTOR STACK

• LAMPE was formerly named DANIELS

• • Only dosimeter monitoring 5

TABLE 2.2 Airborne Gross Beta Activity (fCi/cubic meter +/- 2)

PERIOD Polk Lampe Withers EH&S 2024 1/11 - 1/22 14.9 +/- 2.8 12.6 +/- 2.2 10.8 +/- 2.2 20.8 +/- 3.5 4/11 - 5/1 14.8 +/- 2.6 11.8 +/- 2.2 20.9 +/- 3.4 6.9 +/- 1.6 7/8 - 7/29 18.9 +/- 3.2 15.7 +/- 2.8 14.0 +/- 2.5 17.0 +/- 2.91 10/9 - 10/18 18.0 +/- 3.1 17.6 +/- 3.0 21.7 +/- 3.6 20.1 +/- 3.4 TABLE 2.3 Airborne Gamma Activity LLD Values (fCi/cubic meter)

PERIOD Co-57 Co-60 Nb-95 Zr-95 Ru-103 Ru-106 Cs-134 Cs-137 Ce-141 Ce-144 2024 1/11 - 1/22 0.24 0.43 2.73 0.95 2.13 3.31 0.43 0.81 3.14 1.61 4/11 - 5/1 0.29 0.24 1.67 1.11 1.93 4.56 0.48 0.28 3.26 2.34 7/8 - 7/29 0.27 0.25 0.45 1.01 0.52 4.16 0.28 0.34 0.33 1.12 10/9 - 10/18 0.12 0.25 0.82 0.72 1.61 4.72 0.27 0.46 1.52 1.35 6

TABLE 2.4 REGULATORY LIMITS, ALERT LEVELS, AND BACKGROUND LEVELS FOR AIRBORNE RADIOACTIVITY (fCi M -3).

REGULATORY INVESTIGATION AVERAGE N.C.

NUCLIDE LIMIT 1 LEVEL 2 BACKGROUND LEVEL 3 GROSS BETA 500 20 Cs-137 2 X 105 100 2

Cs-134 2 X 105 100 0

Nb-95 2 X 106 100 0

Zr-95 4 X 105 100 0

1 Regulatory limits given in 10 CFR 20 Appendix B Table 2.

2 Investigation limit for any detected beta or gamma emitting nuclides.

3 This data represents an average value measured in North Carolina at various locations.

Excerpted from 2009 Environmental Surveillance Report produced by the NC Department of Health and Human Services Radiation Protection Section.

3. MILK Milk samples are collected every other year from the Campus Creamery and the Lake Wheeler Road Dairy as processed milk and raw milk and analyzed for I-131. Samples were not tested in 2024.

TABLE 3.1 I-131 IN COWS MILK (pCi Liter -1  2 ) LLD ~ 2 pCi Liter -1 DATE Campus Creamery Lake Wheeler 2024 Not Tested Not Tested 7

4. SURFACE WATER Table 4.1 gives the gross alpha and beta activities measured for water samples taken from Rocky Branch creek at points where it enters (ON), behind Carmichael Gymnasium (GYM) and exits (OFF) the campus. The LLD value for gross alpha and beta activities is ~ 1.5 and 0.9 pCi Liter-1 respectively. For gross alpha activity the investigation limit is 5 pCi/L and the regulatory limit is 15 pCi/L. For gross beta activity the investigation limit is 5 pCi/L and the programmatic limit is 50 pCi/L. Gamma analysis of all samples was also performed. All of the results obtained are consistent with the presence of naturally-occurring radionuclides and none of the gamma emitters listed in Table 4.2 were measurable above detection limits. Finally, Table 4.3 gives the results from tritium analyses of surface water samples, where the investigation limit is 2,000 pCi/L and the regulatory limit is 20,000 pCi/L. No tritium was detectable in any sample above the LLD value of ~ 500 pCi Liter-1.

Any sampling points yielding concentrations approaching the investigation limits are monitored closely, trended, and evaluated for remedial action if determined to be encroaching on an applicable regulatory limit.

TABLE 4.1 GROSS ALPHA AND BETA ACTIVITY IN SURFACE WATER (pCi Liter 1 2)

LLD ~ 1.5 pCi Liter-1 LLD ~ 0.9 pCi Liter 1

GROSS GROSS DATE LOCATION ALPHA BETA 2/9/24 ON 0.9 +/- 0.4 2.1 +/- 0.4 GYM 0.9 +/- 0.4 2.2 +/- 0.4 OFF 1.2 +/- 0.5 2.0 +/- 0.4 5/10/24 ON 0.9 +/- 0.4 2.7 +/- 0.5 GYM 0.5 +/- 0.2 1.5 +/- 0.3 OFF 1.0 +/- 0.4 2.4 +/- 0.4 8/2/24 ON 0.6 +/- 0.3 2.9 +/- 0.5 GYM 0.3 +/- 0.2 2.3 +/- 0.4 OFF 0.2 +/- 0.2 3.0 +/- 0.5 11/5/24 ON 2.5 +/- 0.9 2.8 + 0.5 GYM 1.5 +/- 0.6 2.6 + 0.5 OFF 1.1 +/- 0.5 2.7 + 0.5 8

TABLE 4.2 LLD VALUES FOR GAMMA EMITTERS IN SURFACE WATER NUCLIDE LLD (pCi Liter-1)

Co-60 0.56 Zn-65 1.90 Cs-137 0.70 Cs-134 0.73 Sr-85 2.62 Ru-103 1.57 Ru-106 6.99 Nb-95 1.26 Zr-95 1.45 9

TABLE 4.3 TRITIUM ACTIVITY IN SURFACE WATER (pCi Liter 1 2)

LLD ~ 500 pCi Liter-1 DATE LOCATION TRITIUM CONCENTRATION 2/9/24 ON 53 +/- 377 GYM 189 +/- 384 OFF 55 +/- 385 5/10/24 ON 104 +/- 369 GYM 153 +/- 365 OFF -26 +/- 364 8/2/24 ON

-26 +/- 368 GYM 27 +/- 381 OFF 129 +/- 371 11/5/24 ON 359 +/- 362 GYM 350 +/- 352 OFF 327 +/- 354 10

5. VEGETATION The vegetation sampling is performed every other year and analyzed for gross beta activity as well as gamma activity. Table 5.1 gives gross beta activities for grass samples collected on the NCSU Campus. The alert level for beta activity in vegetation is 20 pCi/g and all levels were below this limit. Table 5.2 lists LLD values for several gamma emitters. Vegetation was not tested in 2024.

TABLE 5.1 GROSS BETA ACTIVITY IN CAMPUS VEGETATION *LLD ~ 0.3 pCi g-1 SAMPLE DATE SAMPLE LOCATION (pCi g-1 2) 2024 NORTH CAMPUS Not Tested 2024 SOUTH CAMPUS Not Tested 2024 EAST CAMPUS Not Tested 2024 WEST CAMPUS Not Tested TABLE 5.2 LLD VALUES FOR GAMMA EMITTERS IN VEGETATION NUCLIDE LLD (pCi g-1)

Co-60 0.01 Zn-65 0.02 Cs-137 0.01 Cs-134 0.01 Sr-85 0.02 Ru-103 0.02 Nb-95 0.02 Zr-95 0.02 11

6. OPTICALLY STIMULATED DOSIMETERS Dosimeter analysis is contracted to Landauer, Inc. for determination of ambient radiation exposures. Exposures are integrated over a three-month period at each of the air monitor stations listed in Table 2.1 and at the PULSTAR Reactor facility. An Area 1 control dosimeter is located in the Environmental Health & Safety Center. Table 6.1 gives the dose equivalent data for these seven (7) locations.

The dose equivalents are reported as millirem per calendar quarter. Readings which fall below the dosimeters minimum measurable quantities (i.e., 1 millirem for gamma radiations and 10 millirem for beta radiation) are reported by the contract vendor with the designation M. The observed readings are typically within the expected range for natural background radiation levels.

TABLE 6.1 ENVIRONMENTAL DOSIMETER DOSES - Millirem per Quarter Period (2022)

Landauer Control Control Area 1 Polk Withers Lampe EHS North PULSTAR 01/01-03/31 35 M

M,M M,M M,M M

M 22 04/01-06/30 36 M

M,M M,M M,M 1

M 23 07/01-09/30 35 M

M,M M,M M,M 2

M 25 10/01-12/31 38 M

M,M M,M M,M M

M 23 Note: Landauer Control dose is measured by the vendors Control Dosimeter which is included with each shipment to monitor radiation exposure received during transit. It is maintained in a radiation free area during the calendar quarter period. Control Area 1 dose is measured by a dosimeter maintained in an office location away from radiation sources.

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7. QUALITY CONTROL INTERCOMPARISON PROGRAM The Environmental Radiation Surveillance Laboratory (ERSL) in the Radiation Safety Division has analyzed samples provided by the U.S. DOE Mixed-Analyte Performance Evaluation Program (MAPEP Test Session 51) Radiological and Environmental Sciences Laboratory (RESL) during this reporting period. The objective of this program is to provide laboratories performing environmental radiation measurements with unknowns to test their analytical techniques.

The MAPEP value listed in the Tables 7.1 and 7.2 to which the ERSL results are compared is the mean of replicate determinations for each nuclide. The MAPEP uncertainty is the standard error of the mean.

For each reported radiological analyte, the laboratory result and the reference value may be used to calculate a relative bias:

The relative bias will place the laboratory result in one of three categories:

Acceptable Bias 20%

Acceptable with Warning... 20% < Bias 30%

Not Acceptable. Bias > 30%

Discussion:

All MAPEP sample analysis results as given in the following tables meet acceptance criteria with relative bias values of < 20%, with the following exceptions:

1.

Table 7.1 MULTI-NUCLIDE WATER SAMPLE - The NCSU reported value for gross alpha was noted to be outside of the acceptance range. The reported value is higher than the accepted MAPEP value, so is therefore considered conservative for the purpose of this analysis. Evaluation and implementation of corrective actions are in process.

2.

Table 7.2 MULTI-NUCLIDE AIR FILTER - The NCSU reported value for Cs-134 in air was 0.22 Bq/filter which is noted to be below the acceptance range, but overlapping the lower end of the range within the quoted uncertainty. This reported value is lower than the acceptance range for the MAPEP value, so is considered non-conservative. This reported value for Cs-134 equates to a concentration of 10.5 fCi/m^3, assuming the typical volume of air sampled. This value is approximately 19,000 times lower than the regulatory limit for Cs-134 in air of 200,000 fCi/m^3.

Evaluation and implementation of corrective actions are in process.

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TABLE 7.1 MULTI-NUCLIDE WATER SAMPLE - INTERCOMPARISON STUDY 01 August 2024 The sample consists of a spiked aliquot of acidified water (~5 % HNO3). The reported values and the known values are given in Bq/Liter.

NCSU - Environmental Laboratory Results (Water Sample) (Bq/L)

Radionuclide Reported Value (NCSU)

Reported Error (NCSU)

MAPEP Value Acceptance Range Co-57 26.0 1.6 26.4 18.5 - 34.3 Co-60 15.3 1.0 15 10.5 - 19.5 Cs-137

-0.22 False Positive Test Cs-134 20.5 1.2 22.3 15.6 - 29.0 Mn-54

-0.69 False Positive Test Zn-65 24.3 1.6 22.8 16.0 - 29.6 Fe-59 63.5 3.9 57.5 40.3 - 74.8 Gross Alpha 3.8 1 1.3 1.29 0.39 - 2.19 Gross Beta 4.34 0.69 5.09 2.55 - 7.64 Note: The entry "-----" indicates no analyte was present 1 See discussion in Section 7 of this report.

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TABLE 7.2 MULTI-NUCLIDE AIR FILTER - INTERCOMPARISON STUDY 01 August 2024 The sample consists of a 50 mm diameter glass fiber filter which has been spiked with a solution and dried. The reported values and the known values are given in Bq/filter.

NCSU - Environmental Laboratory Results (Air Filter) (Bq/Filter)

Radionuclide Reported Value (NCSU)

Reported Error (NCSU)

MAPEP Value Acceptance Range Co-57 0.001 False Positive Test Co-60 0.35 0.025 0.361 0.253 - 0.469 Cs-137 0.26 0.019 0.269 0.188 - 0.350 Cs-134 0.22 1 0.019 0.334 0.234 - 0.434 Mn-54

-0.004 False Positive Test Zn-65

-0.004 False Positive Test Gross Beta 0.76 0.12 0.644 0.322 - 0.966 Note: The entry "-----" indicates no analyte was present 1 See discussion in Section 7 of this report.

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8. CONCLUSIONS The data obtained during this period do not show any detectable fission product activity. The observed environmental radioactivity is due primarily to radon progeny, primordial radionuclides (e.g. K-40) and those radionuclides which originate in the upper atmosphere as the result of cosmic ray interactions. These facts justify the conclusion that the PULSTAR Reactor facility continues to operate safely and does not release fission product materials into the environment.

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