ML24082A089

North Carolina State University - Annual Operating Report for 2023

ML24082A089
Person / Time
Site:	North Carolina State University
Issue date:	03/21/2024
From:	Hawari A North Carolina State University
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
Download: ML24082A089 (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) 21 March 2024 Document Control Desk US Nuclear Regulatory Commission 11555 Rockville Pike Rockville, MD 20852 Re:

Annual Report for 2023 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 Colby Fleming, Manager of Engineering and Operations at 919-515-3347, or via email at ncsorrel@ncsu.edu.

I declare under penalty of perjury that the forgoing is true and correct. Executed on 21 March 2024.

Ayman I. Hawari, Ph. D.

Director, Nuclear Reactor Program North Carolina State University

Enclosures:

Annual Operating Report for 2023 Attachment A: PULSTAR Reactor Environmental Radiation Surveillance Report 2023

Annual Operating Report for 2023

1 NORTH CAROLINA STATE UNIVERSITY DEPARTMENT OF NUCLEAR ENGINEERING PULSTAR REACTOR ANNUAL REPORT DOCKET NUMBER 50-297 For the Period: 01 January 2023 - 31 December 2023 The following annual report for 2023 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 2254 utilization hours in 2023. The following is a brief summary of the types of experiments performed, including for teaching laboratories, courses, research and service:

1/M Approach to criticality Control rod worth measurements Reactivity parameter measurements Core thermal power and coolant temperature measurements Axial power and peaking factor measurements (flux mapping)

Reactor power determination using photodiode arrays Positron annihilation spectroscopy measurements Neutron diffraction measurements Neutron transmission measurements Neutron flux measurements Neutron detector testing and certification Neutron radiographic imaging Isotope production Neutron activation analysis measurements Electronic component irradiation testing Ultracold neutron experimental testing Fuel irradiation facility experimental testing Molten salt irradiation facility experimental testing

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 trend in reactor systems performance during this reporting period:

An unaccounted loss of primary water that began in 2015 continued through 2023. Efforts toward final repair were completed during 2023, and the installation of the temporary repair box was effective in reducing the loss of primary water to minimal levels. 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 redundant reactor power monitoring system (Safety Power Level Channel) failed during operations. All appropriate operator responses were taken, but since channel failure occurred during reactor operation, a TS violation was reported to the NRC. This channel was repaired, and the reactor was returned to normal operations. 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 compliance with ANSI 15.1-2007.

No other significant or unexpected trends in reactor systems 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 2023:

57.3 Megawattdays Critical hours in 2023:

1,468.5 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:

2,253.9 Megawattdays 6.7.4.c Number of Emergency and Unscheduled Shutdowns:

Emergency Shutdowns - NONE Unscheduled Shutdowns - Four 2-JUN-2023 Shutdown due to immediate operator action in response to abnormal channel behavior of the Safety Power Monitoring Channel. The operator observed the Safety Channel to be in disagreement with all other reactor power monitoring channels during the initial approach to power and responded according to procedure.

Subsequent investigation revealed that the detector high voltage power supply had failed, and the unit was replaced with a spare. The channel was recalibrated, and operational checks were completed satisfactory for all reactor systems prior to resumption of normal operations (see ML#0888).

As required by TS, a report was issued to the NRC on 12 June 2023 (Report for Event Number 56553 "Technical Specification Violation" ML23163A190).

3 31-JUL-2023 SCRAM as a result of the loss of commercial power in Burlington Engineering Labs. The reactor system loads were automatically shifted to back-up power until commercial power was restored. A full set of pre-operation checks was completed following restoral of commercial power, and normal operations were resumed.

28-AUG-2023 Shutdown due to immediate operator action in response to the loss of digital recorder signal for the West Wall area radiation monitor. Upon investigation, the radiation monitor was found to be operating and maintained signal for the annunciator, evacuation, and confinement systems. It was determined that the channel was operable as it could perform its intended function, but a fault in the data link with the recorder occurred, resulting in the loss of remote indication. The data link was reestablished, a full set of pre-operation checks was performed, and normal reactor operations were resumed.

20-OCT-2023 SCRAM as a result of the loss of commercial power in Burlington Engineering Labs. The reactor system loads were automatically shifted to back-up power until commercial power was restored. A full set of pre-operation checks was completed following restoral of commercial power and normal operations were resumed.

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 2023 are listed below.

ML#0876 PS-1-07 Neutron Flux Monitoring System (SN002) - Commissioning of The Neutron Flux Monitoring System (NFMS) is in progress. The source range of the NFMS is fully commissioned as the Startup Power Level Channel, but the work is ongoing to bring the NFMS wide range into agreement with other channels in the mid-power range. No annunciations or trips are generated by the wide range component of the NFMS, and the channel is fully capable of performing its intended function.

ML#0883 PS-6-05-2A - Stack Particulate Monitor - Failure of the Stack Particulate Monitor internal HVPS occurred during a period of reactor shutdown causing an automatic initiation of the building evacuation system. The monitor was replaced with a spare unit, calibrated, and the channel was returned to service.

ML#0884 PS-5-09 West Wall Oxygen Monitor (MER) - The west wall oxygen monitor was observed to drift rapidly following calibration, resulting in spurious high-oxygen level alarms. The sensor was shipped to the vendor for maintenance and returned. It was reinstalled, tested satisfactory, and returned to service.

ML#0885 PS-3-02-5A - Secondary Make Up Solenoid (S-22) - The cooling tower was found to be overflowing on 7 March 2023. The cause was found to be the secondary coolant makeup solenoid valve (S-22), which had failed open. The valve was isolated, replaced, and tested satisfactory prior to being returned to service.

ML#0886 PS-6-19 Stack Particulate Monitor and Detector (DC 0818) - The Stack Particulate Monitor channel was replaced in response to ML#0883 and per CR#0818. A sodium iodide scintillation detector was installed to replace the previously used detector and calibrated according to

4 approved procedures. A test of all required functions of the system was completed satisfactory and the system was returned to service.

ML#0887 PS-6-12 Stack Sample Pump - A replacement for the stack sample pump was installed but failed shortly after it was energized. Investigation revealed that the motor starter had been tripped by thermal overload as the current draw of the new pump exceeded the limits of the starter. The old pump was refurbished, tested satisfactory, and reinstalled in the stack sampling system. The stack sample flow rate was verified to be steady and within performance requirements for the system, and normal operations were resumed.

ML#0888 PS-1-05-3A - Safety Channel (High Voltage Power Supply) - During the initial approach to power on 2 June 2023, the Safety Power Monitoring Channel indication was observed to be in disagreement with all other nuclear instruments and the detector high voltage was observed to be out of the acceptable range (see Unscheduled Shutdown 2 June 2023). The reactor was shut down due to abnormal channel behavior. The internal high voltage power supply was found to have failed and was replaced with a spare. The channel was repaired, recalibrated, and tested satisfactory prior to resumption of reactor operation.

ML#0889 PS-3-02-5A - Cooling Tower Bleed Line - During operation, the reactor operator received an Abnormal Coolant Temperature alarm, caused by a loss of secondary cooling. Upon investigation, a break in the cooling tower bleed line was discovered, which resulted in the cooling tower basin draining. The leak was isolated and the cooling tower basin was filled and returned to service. The bleed line was repaired and tested satisfactory prior to being returned to service.

ML#0890 PS-3-03 Primary Resin Change (Demin) - Primary resin resistivity dropped below 1000k-cm, indicating that the primary demineralizer resin needed to be replaced. The resin and the pre/post filters in the primary demineralizer loop were replaced on 31 July 2023.

ML#0891 PS-4-06 Flapper Switch - the reactor operator encountered an unexpected Flapper Not Closed SCRAM during pre-operation checks on 6 Dec 2023, despite the flapper being visually confirmed to be closed. After investigation, it was determined that reduced differential pressure across the core plenum, as a result of the core being unloaded, was insufficient to fully actuate the flapper closed switch. This was confirmed by historical notes and previous reactor operators.

No maintenance was required, but the maintenance log report was completed and retained for future reference. The flapper closed switch was tested satisfactory after the core was loaded and prior to further operation.

ML#0892 PS-4-03 Regulating Rod In-Line Drive - The regulating rod drive motor and magnet were found to have become decoupled during pre-operation checks on 6 Dec 2023, resulting in the control rod magnet remaining stuck at the bottom of travel. This was caused by progressive wear of the coupling block as a result of a deformed motor gearbox output shaft. The gearbox was replaced, and the drive mechanism was tested satisfactory and returned to service. All other control rod drives were carefully examined and were assessed to be in excellent condition.

ML#0893 PS-5-05 BT&TC Exhaust Fan - A reactor operator noted that the Beam Tube and Thermal Column (BT&TC) Exhaust Fan failed to start during per-operation checks on 12 December 2023.

Upon inspection, the fuses supplying power were found to have been overloaded after a motor bearing failed. The fan motor, which was original to the facility, was replaced with an equivalent modern fan motor. The system was tested satisfactory and returned to service.

5 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 2023 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. Based on the screening reviews performed, the change listed below did not require a full 10 CFR 50.59 evaluation.

CN#879 Stack Gas Flow Bypass - Modification to the exhaust effluent monitoring system was made to allow online isolation of the Stack Gas detector and chamber for maintenance and grab sample collection. The change consisted of the addition of a bypass line to the existing system.

Maintenance and surveillance procedures for this system were revised (CN#880, 881, and 883).

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

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

CN#884 Heated Experiments - A proposal to conduct irradiation experiments using purposefully heated volumes and components. No previous heated irradiations have been performed, making this experiment "untried" for the purpose of review. This experiment was reviewed using internal screening procedures, determined to be within the facility license and TS, and approved.

CN#885 Fueled Experiments: 4%-Enriched Fuel Pin Radiographic Imaging - A proposal to use neutron radiography for nondestructive testing and inspection of an unirradiated PULSTAR fuel pin. As the first experiment to irradiate UO2 fuel outside the core, this experiment was reviewed using internal screening procedures, determined to be within the facility license and TS, and approved.

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#878 EP2 Off-Site Notification - Attachment 2 of this procedure was updated to reflect changes to the State Warning Point authentication code list for North Carolina.

CN#880 PS-6-18-2: W1 Fixed Particulate Unit and Grap Sample Unit Operation and Maintenance - This procedure was updated to incorporate modifications made to the stack sampling system (see CN#879). These changes include updates to references, material specifications, instruction for sampling system alignment and operation, updates to Fixed Particulate Unit (FPU) flow rate requirements, and updates to the stack sampling system diagram.

CN#881 PS-6-18-3: W1 Stack Sample Pump Operation and Maintenance - This procedure was updated to incorporate modifications made to the stack sampling system (see CN#879). These changes include removal of references to the previous stack sample pump model, updates to flow rate requirements based on the current pump model, updates to the stack sample system diagram, and deletion of attachment 2 describing the old flow meter, which was replaced with the current digital mass air flow meter.

CN#882 PS-6-19-1: Thermo Radiation Monitor Calibration, Operation, and Maintenance - This procedure was updated to include provision for detector calibration using a small volume point source.

6 CN#883 PS-6-12-6: Test and Inspection of the Stack Sampling System - This procedure was updated to incorporate modifications made to the stack sampling system (see CN#879). Changes include updates to comments on system operation, addition of flow checks with the bypass line open, updates to system check datasheets, and updates to the system diagram.

Other Changes License Renewal and Amendments:

In response to a previous request to separate the Fueled Experiments License Amendment Request (LAR),

vented fueled experiments and corresponding TS and license changes were approved by the NRC.

Corresponding publications from the NRC related to this amendment include the Safety Evaluation Regarding the License Amendment Request for Vented Fueled Experiments (ML23164A214) and the Audit Report Related to the NRC Staff Review of the North Carolina State University License Request Regarding Vented Fueled Experiments (ML23209A716).

A LAR for Level 3 management training requirements was sent to the NRC (ML23187A455). These changes were approved such that the previous requirement that the Manager of Engineering and Operations (MEO) obtain an SRO license within one year of hire was changed to allow for two years to obtain the SRO license.

Corresponding publication from the NRC related to this amendment is North Carolian State University -

Safety Evaluation For The Application For A License Amendment Request For TS 6.1.1 Regarding Training Of Level 3 Management (ML23194A184).

A LAR to allow credit to be taken for prompt remedial action was sent to the NRC (ML23212A973). Per the NRCs request, this amendment was later withdrawn and the proposed changes added to the ongoing license renewal process.

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) 2023 Number of Batches Total Ci Total Volume Liters Diluent Liters Tritium Ci 01 JAN - 31 MAR 2

215 6,620 18,400 212 01 APR - 30 JUN 4

374 12,800 26,200 373 01 JUL - 30 SEP 7

834 22,600 0

833 01 OCT - 31 DEC 4

288 12,500 0

288 2023 1706 Ci of tritium was released during this year.

2023 1711 Ci of total activity was released during this year.

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

7 ii.

Identification of Fission and Activation Products:

The gross beta-gamma activity of the batches in (i) above were less than 210-5 Ci/ml. Isotopic analyses 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 2023 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 2023:

Period in 2023 Total Ci Tritium

µCi Volume Liters 01 JAN - 31 MAR 2,969 2,960 25,063 1 APR - 30 JUN 3,810 3,803 22,469 1 JUL - 30 SEP 3,936 3,930 17,572 1 OCT - 31 DEC 3,419 3,413 15,182 CALENDAR YEAR TOTAL 14,134 14,106 80,286 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 2023 JANUARY 744 0.621 FEBRUARY 672 0.342 MARCH 744 0.428 APRIL 720 0.491 MAY 744 1.115

8 JUNE 720 0.406 JULY 744 0.417 AUGUST 744 0.883 SEPTEMBER 720 1.663 OCTOBER 744 1.082 NOVEMBER 720 0.632 DECEMBER 744 0.232 TOTAL 8760 8.311 (2)

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

Particulate filters from the Stack Particulate Monitoring Channel were analyzed upon removal. Sb-124 (t1/2

= 60.2 days) was detected on two occasions. An estimated total of 2.49x10-4 Ci was released at an average release rate of 1.75x10-13 Ci/mL, which is about 0.02% of the AEC limit listed in 10 CFR 20 Appendix B Table

2. No fission products were detected.

ii.

Gases and Particulates Discharged During the Reporting Period:

(1)

Gases:

Total activity of Argon-41 released was 8.311 Curies in 2023.

The yearly average concentration of Argon-41 released from the PULSTAR reactor facility exhaust stack in 2023 was 4.0310-8 Ci/ml. Dose calculations 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. In addition, Sb-122 (t1/2 = 2.7 days) was detected on two occasions. An estimated total of 7.35x10-4 Ci was released at an average release rate of 5.18x10-13 Ci/mL, which is about 0.02% of the AEC limit listed in 10 CFR 20 Appendix B Table 2. No other activation or fission products were detected.

Solid Waste from Reactor

i.

Total Volume of Solid Waste Packaged Total volume of solid waste was 22.1 ft3.

ii.

Total Activity Involved Total activity for solid waste was 1.09 mCi.

9 iii.

Dates of shipments and disposal Transfer of solid radioactive waste to the university broad scope radioactive materials license was made in January, April, and July 2023. The University Environmental Health and Safety Center arranges disposal of hazardous wastes.

6.7.4.g Personnel Radiation Exposure Report:

Thirty-four 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 3.408 person-rem. Individual deep dose-equivalent ranged from 0.000 rem to 0.543 rem with an average of 0.100 rem.

Four 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:

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

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

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:

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

Contamination was not detectable.

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

Radiation was at background levels in all routinely occupied spaces.

Water samples from Rocky Branch Creek and on-site ground water monitoring wells were analyzed in 2023 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 2023

ATTACHMENT A PULSTAR REACTOR ENVIRONMENTAL RADIATION SURVEILLANCE REPORT FOR THE PERIOD JANUARY 1, 2023 - DECEMBER 31, 2023 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 9

5.

VEGETATION Table 5.1 Gross Beta Activity in Campus Vegetation 10 Table 5.2 LLD Values for Gamma Emitters in Vegetation 10 6.

OPTICALLY STIMULATED DOSIMETERS 11 Table 6.1 Environmental Dosimeter Doses 11 7.

QUALITY CONTROL INTERCOMPARISON PROGRAM 12 Tables 7.1 & 7.2 13 -14 8.

CONCLUSIONS 15 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.

3

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

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

N.E.

Monthly 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)

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 Weekly Weekly Quarterly Quarterly 10 CFR 20 10 CFR 20 Air Dose at 7 Campus Stations +

OSD Dosimeter RSD Quarterly Quarterly 10 CFR 20 Surface Water Rocky Branch Creek Gross Alpha/Beta Gamma Tritium RSD RSD RSD Quarterly Quarterly Quarterly Quarterly Quarterly NCSU NCSU 10 CFR 20 Vegetation NCSU Campus Gross Beta Gamma RSD RSD Semi-annually Every Other Year NCSU NCSU Milk Local Dairy I-131 RSD Monthly 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 33.9 fCi/cubic meter at the Withers station during the week of 11/6/2023 to 11/13/2023. This level of activity was analyzed through gamma spectroscopy and found to be primarily natural Radon products. The annual campus average value was 17.6 fCi/cubic meter which is consistent with previous years.

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 DIRECTION1 DISTANCE2 ELEVATION3 (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 2023 1/06 - 1/25 20.2 +/- 2.2 21.0 +/- 2.2 16.5 +/- 2.0 10.3 +/- 1.7 3/29 - 4/17 17.8 +/- 1.9 15.1 +/- 1.7 16.8 +/- 1.8 4.3 +/- 1.2 6/27 - 7/18 4.9 +/- 1.3 21.3 +/- 2.1 24.1 +/- 2.2 13.2 +/- 1.71 10/26 - 11/13 14.4 +/- 2.1 23.7 +/- 2.5 33.9 +/- 2.9 24.3 +/- 2.5 1 Due to maintenance issues with the air samplers, the EHS sample for Q3 was collected 7/30 - 8/4.

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-137 Ce-141 Ce-144 2023 1/06 - 1/25 0.18 0.55 0.39 0.68 0.26 3.14 0.37 0.30 1.33 3/29 - 4/17 0.19 0.51 1.67 2.01 1.38 3.70 0.19 3.60 3.12 6/27 - 7/18 0.10 0.27 0.52 0.70 0.52 2.16 0.32 1.01 0.84 10/26 - 11/13 0.18 0.45 0.74 0.78 0.30 1.62 0.21 0.66 0.98 6

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

REGULATORY INVESTIGATION

• AVERAGE N.C.

NUCLIDE LIMIT LEVEL BACKGROUND LEVEL GROSS BETA 1000 500 20 Cs-137 2 X 105 100 2

Ce-134 2 X 105 100 0

Nb-95 2 X 106 100 0

Zr-95 400 100 0

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. No I-131 was detected above the MDA for either sample.

TABLE 3.1 I-131 IN COWS MILK (pCi Liter -1 +/- 2 ) LLD ~ 2 pCi Liter -1 DATE Campus Creamery Lake Wheeler 11/6/23 None Detected None Detected 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 Level is 5 pCi Liter-1 and the Regulatory Limit is 15 pCi Liter-1. For gross beta activity the Investigation Level is 12.5 pCi Liter-1 and the Regulatory Limit is 50 pCi Liter-1. 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, tritium activity was analyzed to ensure it does not exceed the regulatory limit of 2 x 104 pCi Liter-1. No tritium was detectable above the LLD value of ~ 500 pCi Liter-1.

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 2/6/23 ON 1.4 +/- 1.0 2.6 +/- 0.6 GYM 0.9 +/- 1.1 3.2 +/- 0.7 OFF 0.5 +/- 0.9 4.0 +/- 0.7 5/17/23 ON 1.3 +/- 1.2 5.3 +/- 0.7 GYM 0.7 +/- 1.0 4.7 +/- 0.7 OFF 0.8 +/- 0.9 3.7 +/- 0.6 8/4/23 ON 0.5 +/- 0.9 2.6 +/- 0.6 GYM 0.6 +/- 1.0 3.0 +/- 0.7 OFF 0.1 +/- 0.8 2.7 +/- 0.6 11/3/23 ON 0.4 +/- 1.6 3.1 + 0.8 GYM 1.7 +/- 2.0 3.0 + 0.8 OFF 0.1 +/- 1.5 1.7 + 0.7 8

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

Co-60 0.70 Zn-65 2.15 Cs-137 0.72 Cs-134 0.67 Sr-85 2.71 Ru-103 1.93 Ru-106 7.60 Nb-95 1.41 Zr-95 2.18 TABLE 4.3 TRITIUM ACTIVITY IN SURFACE WATER (pCi Liter 1 +/- 2)

LLD ~ 500 pCi Liter-1 DATE LOCATION TRITIUM CONCENTRATION 2/6/23 ON 318 +/- 389 GYM 190 +/- 394 OFF 239 +/- 387 5/17/23 ON 254 +/- 368 GYM 129 +/- 369 OFF 234 +/- 375 8/4/23 ON 308 +/- 380 GYM 204 +/- 375 OFF 178 +/- 374 11/3/23 ON 26 +/- 380 GYM

-26 +/- 374 OFF 0 +/- 375 9

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 and none of these isotopes were found above the detection limits.

TABLE 5.1 GROSS BETA ACTIVITY IN CAMPUS VEGETATION

• LLD ~ 0.3 pCi g-1 SAMPLE DATE SAMPLE LOCATION (pCi g-1 +/- 2) 7/24/23 NORTH CAMPUS 6.3 +/- 0.5 7/24/23 SOUTH CAMPUS 4.3 +/- 0.3 7/24/23 EAST CAMPUS 13.5 +/- 0.3 7/24/23 WEST CAMPUS 8.4 +/- 0.2 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 10

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 1

M 25 04/01-06/30 34 M

M,M M,M M,M 1

1 19 07/01-09/30 37 M

M,M 1,M M,M 3

M 23 10/01-12/31 36 M

M,M M,M M,M 1

M 22 1 Dosimeter was lost during the monitoring period due to severe weather and insecure mounting.

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 49) 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%

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TABLE 7.1 MULTINUCLIDE WATER SAMPLE - INTERCOMPARISON STUDY 10 October 2023 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 17.1 0.7 19.3 13.5 - 25.1 Co-60 False Positive Cs-137 7.5 0.4 8.7 6.1 - 11.3 Cs-134 8.9 0.4 11.3 7.9 - 14.7 Mn-54 11.2 0.4 12.7 8.9 - 16.5 Zn-65 17.2 1

19.1 13.4 - 24.8 Gross Alpha 4.05 1 0.35 1.59 0.48 - 2.70 Gross Beta 19.50 0.24 16.27 8.14 - 24.41 Note: The entry "-----" indicates no analyte was present 1 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, and is therefore considered conservative for the purpose of this report. Evaluation and implementation of corrective actions are in process.

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TABLE 7.2 MULTINUCLIDE AIR FILTER - INTERCOMPARISON STUDY 10 October 2023 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 1.5 0.09 1.6 1.1 - 2.1 Co-60 False Positive Cs-137 False Positive Cs-134 1.3 0.07 1.6 1.1 - 2.1 Mn-54 1.5 0.12 1.6 1.1 - 2.0 Zn-65 2.2 0.14 1.9 1.3 - 2.5 Gross Beta 0.86 0.06 0.93 0.46 - 1.39 Note: The entry "-----" indicates no analyte was present 14

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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