ML24031A609

FY2023 Nuclear Material Event Database (NMED) Annual Report

ML24031A609
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Issue date:	01/31/2024
From:	Huntsman D, Sant R NRC/NMSS/DMSST
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DE-AC07-05ID14517 INL/RPT-23-75748
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Text

January 202 4

Nuclear Material Events Database

Annual Report

Fiscal Year 202 3

Prepared for the U.S. Nuclear Regulatory Commission by Idaho National Laboratory (INL/RPT 75748)

DISCLAIMER This information was prepared as an account of work sponsored by an agency of the U.S. Government. Neither the U.S. Government nor any agency thereof, nor any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness, of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. References herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the U.S. Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the U.S. G overnment or any agency thereof.

INL/RPT-23-75748

Nuclear Material Events Database

Annual Report

Fiscal Year 202 3

Robert L. Sant, INL Dante C. Huntsman, INL

Published January 2024

Idaho National Laboratory Nuclear Science and Technology / R egulatory Support Idaho Falls, Idaho 83415

Prepared for the U.S. Nuclear Regulatory Commission Office of Nuclear Material Safety and Safeguards Under U.S. Department of Energy-Idaho Operations Office Contract DE-AC07 -05ID14517

ABSTRACT

This report presents information on trending and analysis of incidents/accidents (events) reported to the Nuclear Regulatory Commission (NRC) that involve radioactive material. The events are reported by NRC licensees, Agreement States, and non-licensees, and are recorded in the NRC s Nuclear Material Events Database (NMED). The reported events are classified into categories (event types) based on event reporting requirements defined in Title 10 of the Code of Federal Regulations. The categories in this report are (1) Lost/Abandoned/Stolen Material [LAS], (2) Medical [MED], (3) Radiation Overexposure [EXP], (4) Release of Licensed Material or Contamination [RLM],

(5) Leaking Sealed Source [LKS], (6) Equipment [EQP], (7) Transportation

[TRS], and (8) Other [OTH].

iii iv CONTENTS

ABSTRACT................................................................................................................................................. iii ACRONYMS.............................................................................................................................................. vii EXECUTIVE

SUMMARY

......................................................................................................................... ix

1. INTRODUCTION.................................................................................................................................... 1 1.1 Overview and Objectives................................................................................................................. 1 1.2 NMED Data...................................................................................................................................... 1

2. ANALYSIS OF NMED DATA................................................................................................................ 3 2.1 All NMED Events............................................................................................................................ 3 2.2 Lost/Abandoned/Stolen Material...................................................................................................... 5 2.2.1 Ten-Year Data......................................................................................................................... 5 2.2.2 FY23 Data............................................................................................................................... 8 2.2.3 Events Recently Added to NMED That Occurred Prior to FY23......................................... 10 2.3 Medical........................................................................................................................................... 13 2.3.1 Ten-Year Data....................................................................................................................... 13 2.3.2 FY23 Data............................................................................................................................. 14 2.3.3 Events Recently Added to NMED That Occurred Prior to FY23......................................... 16 2.4 Radiation Overexposure................................................................................................................. 18 2.4.1 Ten-Year Data....................................................................................................................... 18 2.4.2 FY23 Data............................................................................................................................. 19 2.4.3 Events Recently Added to NMED That Occurred Prior to FY23......................................... 20 2.5 Release of Licensed Material or Contamination............................................................................ 22 2.5.1 Ten-Year Data....................................................................................................................... 22 2.5.2 FY23 Data............................................................................................................................. 23 2.5.3 Events Recently Added to NMED That Occurred Prior to FY23......................................... 23 2.6 Leaking Sealed Sources.................................................................................................................. 25 2.6.1 Ten-Year Data....................................................................................................................... 25 2.6.2 FY23 Data............................................................................................................................. 25 2.6.3 Events Recently Added to NMED That Occurred Prior to FY23......................................... 25 2.7 Equipment...................................................................................................................................... 28 2.7.1 Ten-Year Data....................................................................................................................... 28 2.7.2 FY23 Data............................................................................................................................. 28 2.7.3 Events Recently Added to NMED That Occurred Prior to FY23......................................... 30 2.8 Transportation................................................................................................................................ 33 2.8.1 Ten-Year Data....................................................................................................................... 33 2.8.2 FY23 Data............................................................................................................................. 33 2.8.3 Events Recently Added to NMED That Occurred Prior to FY23......................................... 33 2.9 Other............................................................................................................................................... 35 2.9.1 Ten-Year Data....................................................................................................................... 35 2.9.2 FY23 Data............................................................................................................................. 35 2.9.3 Events Recently Added to NMED That Occurred Prior to FY23......................................... 36

v Appendix A - Event Type Descriptions and Criteria................................................................................ A-1 Appendix B - Statistical Trending Methodology...................................................................................... B-1 Appendix C - IAEA Radionuclide Categorization.................................................................................... C-1 Appendix D - Revision of Data................................................................................................................. D-1

FIGURES

Figure 1. All NMED Events......................................................................................................................... 3 Figure 2. Lost/Abandoned/Stolen Material Events....................................................................................... 5 Figure 3. Medical Events............................................................................................................................ 13 Figure 4. Radiation Overexposure Events.................................................................................................. 18 Figure 5. Release of Licensed Material or Contamination Events.............................................................. 22 Figure 6. Leaking Sealed Source Events.................................................................................................... 25 Figure 7. Equipment Events........................................................................................................................ 28 Figure 8. Transportation Events.................................................................................................................. 33 Figure 9. Other Events................................................................................................................................ 35 Figure D-1. Changes to All NMED Event Data....................................................................................... D-3 Figure D-2. Changes to LAS Data............................................................................................................ D-4 Figure D-3. Changes to MED Data........................................................................................................... D-4 Figure D-4. Changes to EXP Data............................................................................................................ D-5 Figure D-5. Changes to RLM Data........................................................................................................... D-5 Figure D-6. Changes to LKS Data............................................................................................................ D-6 Figure D-7. Changes to EQP Data............................................................................................................ D-6 Figure D-8. Changes to TRS Data............................................................................................................ D-7 Figure D-9. Changes to OTH Data........................................................................................................... D-7

TABLES

Table 1. Summary of Trending Analysis...................................................................................................... 4 Table 2. Number of Sources Lost/Abandoned/Stolen and Sources Not Recovered..................................... 6 Table 3. Summary of IAEA Category 1-3 Sources Not Recovered (FY14 -23)........................................... 7 Table 4. Summary of IAEA Category 1-3 Sources Not Recovered (FY23)................................................. 7 Table 5. Medical and Embryo/Fetus or Nursing Child - AOs or Potential AOs......................................... 13 Table 6. EXP Events Classified by CFR Reporting Requirement.............................................................. 19 Table 7. RLM Events Classified by CFR Reporting Requirement............................................................. 23 Table A-1. Primary LAS Reporting Requirements................................................................................... A-3 Table A-2. Secondary LAS Reporting Requirements............................................................................... A-3 Table A-3. MED Reporting Requirements............................................................................................... A-5 Table A-4. EXP Reporting Requirements................................................................................................. A-7 Table A-5. RLM Reporting Requirements............................................................................................... A-8 Table A-6. LKS Reporting Requirements................................................................................................. A-9 Table A-7. EQP Reporting Requirements............................................................................................... A-10 Table A-8. TRS Reporting Requirements............................................................................................... A-12 Table A-9. OTH Reporting Requirements.............................................................................................. A-13 Table C-1. IAEA Code of Conduct Category 1 through 5 Radionuclide Activity Thresholds................. C-4

vi ACRONYMS

ALARA as low as reasonably achievable ALI annual limit on intake AO abnormal occurrence AQL acceptable quality limit BRC Bureau of Radiation Control CDE committed dose equivalent CEDE committed effective dose equivalent CFR code of federal regulations CST central standard time CT computed tomography DDE deep dose equivalent DE dose equivalent DEP Department of Environmental Protection DOH Department of Health DSHS Department of State Health Services EDE effective dose equivalent EMA Emergency Management Agency EQP equipment (NMED event type)

EXP radiation overexposure (NMED event type)

FBI Federal Bureau of Investigation GPS global positioning system GTCC greater than class C HDR high dose rate HHSA Health and Human Services Agency HLW high level waste IAEA International Atomic Energy Agency INES International Nuclear and Radiological Event Scale INL Idaho National Laboratory IVB intravascular brachytherapy LAS lost/abandoned/stolen material (NMED event type)

LKS leaking sealed source (NMED event type)

LS least squares MED medical (NMED event type)

vii MST mountain standard time NMED Nuclear Material Events Database NRC Nuclear Regulatory Commission NUREG Nuclear Regulatory Commission Regulation OTH other (NMED event type)

PET positron emission tomography QC quality control RCP Radiation Control Program REAC/TS Radiation Emergency Assistance Center/Training Site RLM release of l icensed material or c ontamination (NMED event type)

RSO radiation safety officer SDE shallow dose equivalent SNM special nuclear material SSE error sum of squares SSR regression sum of squares SST total sum of squares TEDE total effective dose equivalent TRS transportation (NMED event type)

viii EXECUTIVE

SUMMARY

The Nuclear Regulatory Commissions (NRC) Nuclear Material Events Database (NMED) contains records of events involving nuclear material reported to the NRC by NRC licensees, Agreement States, and non-licensees. The reported events are classified based on reporting requirements defined by Title 10 of the Code of Federal Regulations. The event reports are evaluated to identify statistically significant trends and events of higher significance (referred to as significant events in this report).

The significant events that occurred in Fiscal Year 202 3 are summarized below. Some of these events are considered potential Abnormal Occurrences (AOs ) until they complete NRCs formal AO determination process and are reported in NUREG-0090, Report to Congress on Abnormal Occurrences. Note that a single event may be listed with more than one event type.

Lost/Abandoned/Stolen Radioactive Sources/Material Events Five significant events occurred involving the loss of six Category 1-3 sources as defined by the International Atomic Energy Agencys Code of Conduct on the Safety and Security of Radioactive Sources (2004). No Category 1 sources, four Category 2 sources, and two Category 3 sources were lost; all of which were recovered except for one Category 3 source.

Regarding the five significant events:

• Three events involved the loss of Category 2 sources (four sources total). One event involved the theft and recovery of a vehicle that contained a source, one event involved a source stolen from a company vehicle (the source was subsequently recovered at an apartment complex), and one event involved two sources temporarily lost in transit by a common carrier.

• Two events involved the loss of Category 3 sources (two sources total). In both events, the sources were lost by a common carrier during shipping and one of the sources was subsequently recovered.

In addition to the five events above, one other significant event occurred prior to FY23 and was recently added to NMED. In this event, three sources were held by a common carrier awaiting payment from a vendor. All three sources were subsequently recovered.

Medical Events Seven significant events occurred, all of which were classified as potential Abnormal Occurrences. In four events, patients received dose to the wrong liver lobe/segment during Y -90 mi crosphere treatments.

The other three events involved high dose rate treatment issues, including two in which multiple fractions were delivered at the same time and one in which the dose was delivered to the wrong site.

Radiation Overexposure Events Three significant events occurred. Each event involved an overexposure to radiography personnel during operations.

Release of Licensed Material or Contamination Events Two significant events occurred. One event involved Th-232 powder being mixed with paint, which was used in a private individual's home. The other event involved a transected I -125 localization seed.

Leaking Sealed Source Events No significant events occurred.

Equipment Events Three significant events occurred. In one event, the source fell out of a fixed gauge, likely due to vibration. In another event, a disconnected radiography source resulted in an overexposure to a radiographer. The final event involved a transected I -125 localization seed.

ix Transportation Events No significant events occurred.

Other Events One significant event occurred, which was also classified as a potential Abnormal Occurrence. In this event, an embryo/fetus received a radiation dose when a patient who was unknowingly pregnant received an I-131 treatment.

x Nuclear Material Events Database Annual Report: Fiscal Year 202 3

1. INTRODUCTION

1.1 Overview and Objectives Nuclear material event reports are evaluated to identify statistically significant trends and significant events. The reported information aids in understanding why the events occurred and in identifying any actions necessary to improve the effectiveness of the nuclear material regulatory program.

A database for tracking nuclear material events was developed by the Nuclear Regulatory Commission (NRC) in 1981. In 1993, using existing material events databases, the NRC developed a new and more comprehensive database for tracking material events. This database, designated the Nuclear Material Events Database (NMED), contains records of events involving nuclear material reported to the NRC by NRC licensees, Agreement States, and non-licensees. The database is maintained by Idaho National Laboratory (INL) and contains approximately 28,000 records of material events submitted to the NRC from January 1990 to present.

The events in this report are classified into the following categories (event types) based on event reporting requirements defined by Title 10 of the Code of Federal Regulations (CFR):

• Lost/Abandoned/Stolen Material (LAS),

• Medical (MED),

• Radiation Overexposure (EXP),

• Release of Licensed Material or Contamination (RLM),

• Leaking Sealed Source (LKS),

• Equipment (EQP),

• Transportation (TRS), and

• Other (OTH).

A description of event types addressed in this report and associated screening criteria are presented in Appendix A.

1.2 NMED Data A single event report may be captured with more than one NMED event type. For example, a report may describe a loss of licensed material that also resulted in a radiation overexposure. In such a case, both event types are recorded in NMED and identified by the same report number (referred to as an item number).

The data presented in this report are limited to reportable events that occurred between October 1, 2013, and September 30, 2023. The data were downloaded from NMED on November 27, 20 23. Because NMED is a dynamic database that is updated daily, variations in data may be encountered over time.

Furthermore, even though many events were reported and entered in the database for operational experience purposes, only those events required to be reported by 10 CFR are addressed in this report.

This report displays annual trend data for each of the event types for a 10-year period. A trend analysis was performed on each event type to identify the existence or absence of a statistically significant trend. If a statistically significant trend exists, the display indicates the direction and approximate rate of change

1 with a trend line. For the purposes of this report, a statistically significan t trend exists if the analysis indicates that the computed fit and slope of a least squares linear model is valid at a 95% confidence level.

A primer on the statistical methods employed in the trend analysis is presented in Appendix B.

Note that the trending methodology is not normalized; the trend only considers the number of reported events and does not directly account for external issues such as changes to regulatory requirements or changes in the number of licensees. For example, an increasing trend in the number of medical events could be caused by an increase in the number of medical procedures being performed. Likewise, an event type showing a decreasing trend for NRC licensees and an increasing trend for Agreement State licensees could be caused by S tates becoming Agreement States (resulting in fewer NRC licensees and more Agreement State licensees).

Reporting guidance for Agreement States is provided in the Handbook on Nuclear Material Event Reporting in the Agreement States. The handbook is an appendix to the NRC Office of Nuclear Material Safety and Safeguards procedure SA -300, Reporting Material Events. Access to NMED is available to the staff of NRC, Agreement State, and Federal agencies at https://nmed.inl.gov.

For assistance on searches or other questions, contact Michele Burgess (nmednrc@nrc.gov, 301-415-5868).

2

2. ANALYSIS OF NMED DATA

Event reports submitted to the NRC involving nuclear material are reviewed, categorized, and entered into NMED. Charts are provided to display trends in annual data for the most recent 10-year period (FY14-2 3).

2.1 All NMED Events Figure 1 displays the annual number and trend of NMED events that occurred during the 10- year period.

The trend analysis determined that the NRC-regulated events, the Agreement State-regulated events, and the Total events represent statistically significant decreasing trends (indicated by the trendline s).

800

600 515 504 494

439 443 450 389 396 376 400 350

200

0 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023

Fiscal Year

NRC Agreement State Total

Figure 1. All NMED Events (4,356 total)

The following observations are made regarding the data in Figure 1.

• In FY23, 348 event reports (unique item numbers) accounted for 376 types of event s (event types); a single event report can be classified with different event types.

• The COVID-19 pandemic likely contributed to the decrease in events beginning in 2020.

• The most recent years data are typically many records less than their final value when subsequent updates and late reports are received (see Appendix D, Figure D -1).

• The transition of states from NRC to Agreement State jurisdiction could result in increasing trends in Agreement State data and decreasing trends in NRC data.

3 Table 1 displays a summary of the trending analysis for all NMED event types included in this report. A more detailed discussion of the trending analysis results can be found in the section of this report devoted to each event type.

Table 1. Summary of Trending Analysis Event Type Total NRC Agreement State

All NMED Events

Lost/Abandoned/Stolen Material (LAS)

Medical (MED) - - -

Radiation Overexposure (EXP) - - -

Release of Licensed Material or Contamination (RLM) - - -

Leaking Sealed Source (LKS) - -

Equipment (EQP) -

Transportation (TRS)

Other (OTH) NA NA NA

Notes:

• indicates a statistically significant increasing trend.

• indicates a statistically significant decreasing trend.

• - indicates no statically significant trend.

• NA Not Applicable; indicates that the data does not support trending analysis.

4 2.2 Lost/Abandoned/Stolen Material 2.2.1 Ten-Year Data Figure 2 displays the annual number and trend of LAS events that occurred during the 10-year period.

The trend analysis determined that the NRC-regulated events, the Agreement State-regulated events, and the Total events represent statistically significant decreasing trends (indicated by the trendline s).

400

300 257 245 244 241

191 197 186 200 166 174

145

100

0 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 Fiscal Year

NRC Agreement State Total

Figure 2. Lost/Abandoned/Stolen Material Events (2,046 total)

Appendix C contains a list of radionuclides derived from the International Atomic Energy Agencys (IAEA) Code of Conduct on the Safety and Security of Radioactive Sources (2004). These radionuclides are grouped by the amount of radioactivity into five categories that correspond to the relative hazard, with Category 1 being the most hazardous.

For this report, IAEA Category 1 through 3 source events (excluding irretrievable well-logging source events) are considered significant. Regardless of IAEA category, events involving irretrievable well-logging sources are not considered significant. Events possessing one or more unusual aspects, but that do not meet the significant event threshold, are considered events of interest.

Table 2 displays the number of sources lost (approximately 3,906, excluding irretrievable well-logging sources) during the 10 -year period and the number that have not been recovered (approximately 2,400),

grouped by IAEA category where possible. These included three Category 1 sources, 7 3 Category 2 sources, and 4 0 Category 3 sources; all of which were recovered, with the exception of one Category 2 and seven Category 3 sources.

5 Table 2. Number of Sources Lost/Abandoned/Stolen (LAS) and Sources N ot Recovered (NR) - Excluding Irretrievable Well Logging Sources Fiscal Year Category 201 4 201 5 2016 201 7 201 8 2019 2020 202 1 202 2 202 3 Total LAS4 0 2 0 0 0 0 1 0 0 0 3 1

NR5 0 0 0 0 0 0 0 0 0 0 0

LAS 5 9 8 7 3 9 4 16 8 4 73 2

NR 0 0 0 1 0 0 0 0 0 0 1

LAS 4 4 5 1 4 5 3 5 7 2 40 3

NR 0 1 0 0 0 2 2 1 0 1 7

LAS 53 45 43 37 39 51 57 62 66 46 499 4

NR 25 19 17 11 16 22 24 34 32 24 224

LAS 88 87 83 56 76 67 61 71 78 60 727 5

NR 32 33 45 16 27 24 16 35 38 26 292

LAS 1 2 1 10 4 2 2 0 1 0 23

< 5 NR 0 2 1 1 4 1 2 0 1 0 12 Activity LAS 3 3 1 1 3 4 16 0 3 10 44 Not Known1 NR 0 1 0 0 0 1 0 0 0 0 2

Nuclide LAS 0 1 0 1 0 0 0 1 0 1 4 Not Known2 NR 0 0 0 0 0 0 0 0 0 0 0

LAS 330 201 252 165 281 501 279 170 165 149 2493 Other3 NR 257 110 187 75 173 395 247 154 135 129 1862

LAS 484 354 393 278 410 639 423 325 328 272 3906 Total NR 314 166 250 104 220 445 291 224 206 180 2400 Notes:

1. The Activity Not Known category includes sources containing radionuclides listed in Appendix C for which the activity was not reported. Therefore, the sources were not included in Categories 1 through 5.

2. The Nuclide Not Known category includes those sources for which the radionuclide was not reported. Thus, the sources were not included in Categories 1 through 5 or Other.

3. The Other category includes sources containing radionuclides not included in Appendix C.

4. Events involving a larger number of sources are sometimes entered as a single source with an aggregate activity (for example, the loss of a container of brachytherapy seeds may be entered as a single source with a total combined activity).

6

5. Events involving the loss/theft of multiple sources may involve the recovery of only some of the sources and are entered as being partially recovered (rather than marking each source individually).

The Category 1 thr ough 3 not recovered source counts were corrected for the partially recovered source events.

Tables 3 and 4 provide more detail regarding the 10-year and current year not -recovered data highlighted in Table 2 in yellow and green, respectively. Table 3 displays radionuclide data pertaining to the IAEA Category 1 through 3 sources lost during the 10-year period that have not yet been recovered.

The Decayed Activity values are conservative estimates in that the values are typically decayed from the loss date instead of the manufacture rs assay date. As a result, the actual decayed activities (based on the manufacturer s assay date) are likely less than the estimates. Table 4 is similar to Table 3 but limited to the current year.

Table 3. Summary of IAEA Category 1-3 Sources Not Recovered (FY 14-2 3)

Number of Total Total Total Sources Not Activity Decayed Activity Decayed Activity Radionuclide Half-l ife1 Recovered 2,3 (Ci) (Ci)4 IAEA Category Ir-192 73.83 days 7 103.0 0.8 4

Pu-238 87.7 years 1 2.8 2.6 3

Total 8 105.8 3.4 3

Notes:

1. Half-life values from the Chart of the Nuclides, 16 th Edition.

2. Events involving a larger number of sources are sometimes entered as a single source with an aggregate activity (for example, the loss of a container of brachytherapy seeds may be entered as a single source with a total combined activity).

3. Events involving the loss/theft of multiple sources may involve the recovery of only some of the sources and are entered as being partially recovered (rather than marking each source individually).

The source counts were corrected for the "partially recovered" source events.

4. The source activities were decayed from the event date to 11/ 27/202 3 (data download date).

Table 4. Summary of IAEA Category 1-3 Sources Not Recovered ( FY23)

Number of Total Total Total Sources Not Activity Decayed Activity Decayed Activity Radionuclide Half-l ife1 Recovered 2,3 (Ci) (Ci)4 IAEA Category Ir-192 73.83 days 1 10.8 0.8 4

Total 1 10.8 0.8 4

Notes:

1. Half-life values from the Chart of the Nuclides, 16 th Edition.

2. Events involving a larger number of sources are sometimes entered as a single source with an aggregate activity (for example, the loss of a container of brachytherapy seeds may be entered as a single source with a total combined activity).

3. Events involving the loss/theft of multiple sources may involve the recovery of only some of the sources and are entered as being partially recovered (rather than marking each source individually).

The source counts were corrected for the partially recovered source events.

7

4. The source activities were decayed from the event date to 11/ 27/202 3 (data download date).

2.2.2 FY23 Data One hundred forty-five LAS events occurred in FY23, three of which involved irretrievable well logging sources. Excluding the irretrievable well logging source s, approximately 272 sources were lost/abandoned/stolen, 180 of which have not been recovered. Of the 272 lost sources, n one were Category 1, four were Category 2, and two were Category 3 sources ; all of which were recovered except for one Category 3 source.

Five of the LAS events were considered significant (involved Category 1-3 sources). Note that regardless of IAEA category, events involving irretrievable well logging sources are not considered significant.

Significant Events - Category 1 Source Events None Significant Events - Category 2 Source Events Item Number 220493 - The licensee (a radiography services company) reported the theft and recovery of a vehicle that contained a radiography exposure device with a 1.94 TBq (52.3 Ci) Ir -192 sealed source in the locked and shielded position. The vehicle was stolen from a temporary jobsite at 0710 MST on 11/14/2022. The vehicle was recovered later that same day at 1023 MST. The RSO was immediately notified. The RSO notified local law enforcement. No damage to the source was indicated. The police investigated this event. This event is also classified as a Potential Abnormal Occurrence.

Item Number 230097 - The licensee (a radiography services company) reported that a radiography exposure device containing a 4.48 TBq (121 Ci) Ir -192 source was stolen from a company truck. The radiography crew left the job site to get some food sometime before midnight on 3/8/2023. They stopped at a fast-food restaurant and went inside to eat. They failed to set the alarm to the dark room and left the key to the exposure device's transport box in the dark room. When they returned to the job site, they discovered that the exposure device was missing. They contacted their RSO. A search failed to locate the device. The RSO reviewed security footage at the work location and confirmed that the device had not been left on the tailgate of the truck when the crew left the job site. They reviewed security footage at the restaurant, but the truck was not in the camera's field of view. Local law enforcement, pawn shops, and scrap dealers were notified. The licensee offered a reward for recovery of the device. The Texas Department of State Health Services (DSHS) responded to the location of the theft on 3/9/2023 and searched the area, but did not locate the device. On 3/15/2023, DSHS used global positioning system (GPS) records to determine that the theft occurred between 2314 and 2355 CST on 3/8/2023. DSHS conducted interviews with personnel involved in the event. It was determined that the source storage box had not been locked. It was also determined that the door to the dark room had not been locked because the radiographer had lost the key. The alarm to the dark room was not set because the radiographer forgot to set it. The local Bomb Squad, FBI, DSHS, and the licensee searched extensively for the device, but did not recover it. The RSO stated that personnel were sent back to the area where the theft occurred for additional searches. Corrective actions included providing new and additional training to personnel. In addition, the licensee temporarily suspended the qualifications of the involved personnel. DSHS received a call on 5/23/2023 from an apartment manager, stating that he was cleaning an apartment and found an exposure device on the balcony of the apartment. The manager provided the serial number of the device, which matched the number of the stolen device. DSHS contacted the licensee, who drove to the location and recovered the device on 6/14/2023. The apartment had been vacant since 4/26/2023. The licensee stated that the source was still fully shielded and that dose rates on the device were normal. DSHS notified the FBI special agent who was involved with the incident and local law enforcement. As of 3/9/2023, this incident had a final INES Rating Level of 2. This event is also classified as a Potential Abnormal Occurrence.

Item Number 230288 - The licensee (a radiography equipment manufacturer) reported the loss of two packages containing Ir -192 sources destined for delivery to a company in Columbia. The packages were

8 in a single source changer and they were shipped on 6/26/2023. The missing source changer contained two sealed sources (assayed 6/22/2023) with activities of 3.38 TBq (91.3 Ci) and 3.38 TBq (91.4 Ci). The licensee discovered the incident on 7/10/2023 at 1553. The licensee stated that the missing source changer was last identified at the common carrier's sorting facility in Memphis, Tennessee, on 7/1/2023. The licensee then reported on 7/11/2023 at 1300 that the missing package was found by the common carrier at their Memphis facility. The likely cause was determined to be mishandling by the common carrier. The package was shipped on to its intended destination b y the common carrier.

Significant Events - Category 3 Source Events Item Number 230140 - The licensee (a medical equipment manufacturer) reported the loss of a radioactive source. The Ir-192 source was shipped via common carrier to a medical facility in Elk Grove Village, Illinois. The shipment's last known location was the common carrier's hub in Memphis, Tennessee. The source activity was 400 GBq (10.81 Ci) when it was shipped on 2/17/2023. As of 3/31/2023, the activity was 269.8 GBq (7.29 Ci). The common carrier stated that an exhaustive manual search was completed, but the parcel wa s no longer in their control.

Item Number 230144 - The licensee (a radiography services company) reported that a 621.6 GBq (16.8 Ci) Ir-192 source w as lost in shipment. The licensee stated that tracking was lost on the package. The source was shipped out of the country to Saint Thomas, U.S. Virgin Islands, and was on return shipment.

The common carrier stated that the package was tendered to them on 3/16/2023 with the expectation of delivery on 3/17/2023, barring delays in Customs. The common carrier's records indicated that the shipment arrived at their port of entry at their central sorting facility in Memphis, Tennessee, on 3/17/2023 and went into the Customs c learance process. After Customs delays resulting from clearance paperwork issues, the paperwork was resolved. Customs clearance was completed on 3/27/2023 and the package was removed from the cage. However, the common carrier was unable to verify the status of the package past that point. The common carrier's tracing specialists continued to search for the shipment.

The shipment was subsequently returned to the licensee. The State of Florida Bureau of Radiation Control performed a site visit on 4/3/2023 and confirmed receipt of the source.

Events of Interest Item Number 230001 - A consultant health physicist reported that a portable density gauge had been found. The gauge contained a 111 MBq (3 mCi) Ra -Be source. The gauge was found in a trash transfer trailer entering a landfill on 12/2/2022. The load originated from West Virginia. The load was isolated until the consultant health physicist was able to respond on 12/13/2022. A gamma radiation measurement obtained on contact with the source housing was 18 mR/hr, with 5 mR/hr at one foot. No evaluation was obtained of the neutron dose rate. The device was placed in a locked storage shed posted with a "Caution

- Radioactive Material" sign. Pennsylvania Department of Environmental Protection performed an investigation and was onsite during the recovery of the gauge. There was a partial business card attached to the gauge that listed a government agency. The gauge was picked up on 2/10/2023 for disposal.

Item Number 230096 - The licensee (a medical center) reported the loss of 28 Gd-153 sources with a total activity of 4.14 GBq (112 mCi). A vendor was contracted to remove and dispose of outdated medical equipment. The licensee thought that the Gd-153 sources had been removed from the equipment prior to removal of the equipment from the hospital on 3/7/2023. Upon realizing on 3/8/2023 that the sources had not been removed, the licensee contacted the vendor. The truck was secured in a warehouse near Cleveland, Ohio, and a conservative exclusion zone was maintained. The sources were retrieved by a qualified engineer on 3/10/2023 and were returned to the licensee pending disposal. It was confirmed that the sources had been in a safe and locked position the entire time and there was no indication of tampering. There was no additional radiation exposure to the public or employees. This event was caused by the failure to verify that the sources had been removed from the equipment prior to shipment.

Corrective actions included procedure revision.

9 Item Number 230123 - A recycling facility reported the discovery of a radioactive source within a bin of shredded metal from their onsite operations when it was screened at the scale-house radiation detectors on 3/16/2023. Recycling facility personnel dumped out the container and used tools to sort the contents until the source of radiation was located using a Ludlum 3 with a 44-10 NaI detector. The source was moved to a secure onsite storage area. The California Health and Human Services Agency (HHSA) was notified.

An HHSA inspector visited the site on 3/17/2023 and verified that the radioactive source was in a secure location. The source was placed in a lead shielded container by the inspector and left in the locked storage area. The exposure rate on the lead shielded container was approximately 250 µR/hr. On 3/23/2023, inspectors identified the source as Gd-153 with an approximate activity of 3.7 GBq (100 mCi). HHSA planned to take custody of the source and perform an exposure assessment of the recycling facility's personnel involved in the search for the source.

Item Number 230174 - A recycling facility reported that a load of scrap metal from another recycling facility set off their radiation monitor alarm on 4/18/2023. The load was returned to the originating recycling facility and was separated. A Ra-Be source was identified. The source container/gauge was mostly intact. The originating recycling facility was able to construct a cement barrier to store the source until further investigation could be conducted. Measured radiation exposure rates around the cement barrier showed rates indistinguishable from background (gamma and neutron). The markings on the source container/surface moisture probe identified the manufacturer and the activity as 185 MBq (5 mCi -

assayed 4/30/1963). The gauge was secured and a provisional license was issued on 7/10/2023.

Item Number 230244 - A scrap metal facility reported that a load of scrap metal set off their radiation monitor alarms on 6/2/2023. The radioactive material was identified as an inline-type density gauge. The gauge contained a 7.4 GBq (200 mCi) Cs -137 source. The gauge was secured at the scrap metal facility.

The scrap metal facility found a phone number on the gauge on 6/5/2023 that stated to call a well logging tool manufacturing company if the gauge was found. The well logging tool manufacturing company was contacted and stated that the gauge had been sold to a well logging company. Texas Department of State Health Services (DSHS) and the scrap metal recycling facility contacted the well logging company, who picked up the gauge on 6/6/2023. The well logging company had purchased the gauge and installed it on a well logging vehicle that was later sent for refurbishment, but the gauge had not been removed from the undercarriage. During vehicle refurbishment, the gauge was ripped off and added to the scrap pile by a technician who was unaware it contained a radioactive source. The oil field operator conducted training with their staff. The highest radiation exposure to a member of the public was determined to be 3.75 µSv (375 µrem).

Item Number 230358 - The licensee (a mining company) reported that a 1.85 GBq (50 mCi) Cs -137 source had fallen out of a pipe flow density gamma gauge at their facility in Bartow, Florida. The source was found on the ground adjacent to the gauge on 8/28/2023. The cause is believed to be equipment vibration. The area was secured and restricted. The licensee had no radiological survey instruments.

Florida Bureau of Radiation Control (BRC) responded to the site to investigate and secure the source. The BRC inspector returned to the site on 8/29/2023 and verified that a radiological services provider had returned the source to the shielded position within the gauge. The gauge remained out -of-service pending removal from the piping system. BRC verified that the gauge manufacturer sold the gauge to the licensee, but the sale was not reported to BRC by any party. This event is also classified as an EQP event.

2.2.3 Events Recently Added to NMED That Occurred Prior to FY23 Nineteen LAS events were recently added to NMED that occurred prior to the current fiscal year and had not been included in any previous annual report. One of these events was considered significant. Note that this data may differ from the associated Appendix D graph, which displays the number of events added and subtracted from specific years within the most recent 10-year period, including events moved between years due to changes in the recorded event date.

10 Significant Events - Category 1 Source Events None Significant Events - Category 2 Source Events Item Number 230160 - The licensee (a radiography equipment manufacturer ) reported shipping three source carriers containing three Ir-192 radiography sources to Miami, Florida, for export to a customer in Venezuela on 9/27/2022. Each source contained an activity of 3.81 TBq (103 Ci). The sources did not reach the customer. The sources were reported missing by the licensee on 4/10/2023. The routing took the sources to a broker in Hialeah, Florida. The broker handed the sources off to a freight forwarder in Doral, Florida. The freight forwarder handed the sources off to a common carrier on 10/9/2022. The licensee was told that the common carrier was holding the sources hostage for payment from another vendor. The sources were subsequently recovered from the common carrier's warehouse in Doral, Florida, by Florida Bureau Radiation Control and Florida Law Enforcement personnel on 4/12/2023. The sources were sent to the licensee facility in LaPorte, Texas, and arrived on 4/18/2023.

Significant Events - Category 3 Source Events None Events of Interest Item Number 230048 - The licensee (a generally licensed recycling center) reported that five fixed nuclear gauges were involved in a fire and then stolen. Four gauges contained 740 MBq (20 mCi) Cs -137 sources and one contained a 1,110 MBq (30 mCi) Cs -137 source. A facility fire occurred on 9/26/2022. A sealed drum holding the five gauges was impacted by the fire. It was unclear if there was any impact to the gauges by the fire. Illinois Emergency Management Agency (EMA) staff attempted to perform a reactive inspection on the morning of 2/6/2023. That effort confirmed that the licensee lost accountability of the gauges as it appeared that they had been stolen. The last known location of the gauges was in Sauget, Illinois, on 9/26/2022, when the storage location was involved in the fire. Local scrap yards and public safety partners were notified. Two of the gauges are identified as being fireproof (rated above 800 degrees Celsius for 30 minutes), while the other three gauges are lead-filled. The property owner was contacted on 3/7/2023 to coordinate a site visit. EMA was advised that all assets had been transferred to a new property owner on 2/23/2023 by matter of court decision. EMA coordinated with the new property owner and performed a site visit on 3/30/2023. EMA performed radiation surveys for nearly 2.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> to attempt to locate the gauges. While it is possible the gauges were buried beneath debris, surveys on accessible surfaces did not show evidence of the gauges. Sodium iodide surveys performed throughout the site yielded count rates that were indistinguishable from background. The area was secured. Site cleanup continued and the new owner knew to coordinate with EMA if anything suspect wa s located. The contractor possessed radiation detection equipment. All available evidence indicated that the gauges were no longer on the site and were either stolen or improperly transferred. This event is also classified as an EQP event.

Item Number 230294 - In September 2021, the licensee (a military facility) transferred and disposed of items containing radioactive material as waste to an unauthorized scrap metal facility in Tucson, Arizona.

This event was identified in September 2022 when the program director for the Arizona Bureau of Radiation Control toured the non-licensed waste facility and identified five drums of radioactive waste from the licensee. The NRC was notified for follow -up activities. The division's commander was contacted on 3/15/2023. The NRC determined that the licensee had received and possessed the items under a general license. When the licensee decided to dispose of the items in September 2021, they did not have a functioning program for the management of generally licensed items. This resulted in the items being erroneously characterized as "Military Operational Use" items, which led to the items being incorrectly considered as exempt and disposed of as regular scrap metal. A 30-gallon drum contained 236 luminous switches and dials with approximately 1 MBq (27 µCi) of Ra -226; the highest does rate was about 1.4 mR/hr at 30 cm. Four 55-gallon drums contained 42 exit signs with approximately 1.55 TBq (232 Ci) of H-3 and 254 exempt smoke detectors containing Am -241; the highest dose rate around these

11 drums was near background (around 9 µR/hr) at contact. The drums were stored in a fenced area. The NRC estimated that no dose was received by personnel. The licensee retrieved the drums and properly disposed of them through a licensed waste handler. To prevent recurrence, the licensee updated procedures and provided training to applicable personnel.

Item Number 230390 - During an NRC inspection, it was determined that an environmental services company received and accepted byproduct material without authorization under a specific or general license. On 6/4/2019, the environmental services company accepted 637 tritium gun sight components containing approximately 4.5 TBq (117.7 Ci) of H -3 from a waste management company. The shipping manifest incorrectly characterized the shipment as only containing exempt items. This (and other circumstances) prevented the environmental services company's material receipt inspection procedures from allowing the identification of the non-exempt material.

12 2.3 Medical 2.3.1 Ten-Year Data Figure 3 displays the annual number and trend of MED events that occurred during the 10 -year period.

The trend analysis determined that the data does not represent statistically significant trends in the number of events (indicated by the absence of trendlines ).

100

75 65 56 58 52 51 54 50 47 45 46 44

25

0 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023

Fiscal Year

NRC Agreement State Total

Figure 3. Medical Events (518 total)

Table 5 lists the number of MED events that were classified as Abnormal Occurrences (AOs) in NUREG-0090, Report to Congress on Abnormal Occurrences. Note that recent events are considered potential AOs until they complete NRCs formal AO determination process and are reported in NUREG-0090.

Potential AO events are included in Table 5. Also included are events involving doses to an embryo/fetus or a nursing child (reportable per 10 CFR 35.3047). By definition, these events are not medical events (reportable per 10 CFR 35.3045) and are captured in NMED as an Other event. However, they are also included here for reference.

Table 5. Medical and Embryo/Fetus or Nursing Child - AOs or Potential AOs Fiscal Year

201 4 201 5 201 6 201 7 201 8 201 9 2020 202 1 202 2 202 3 Total

Medical 11 14 7 10 8 7 8 7 7 7 86

Embryo 1 1 1 0 0 0 1 0 1 1 6

Total 12 15 8 10 8 7 9 7 8 8 92

13 For this report, events classified as AOs (or potential AOs) are considered significant. Events possessing one or more unusual aspects, but that do not meet the significant event threshold, are considered events of interest.

2.3.2 FY23 Data Fifty-eight MED events occurred in FY23, seven of which were considered significant and classified as potential AOs.

Significant Events - AOs or Potential AOs Item Number 220495 - The licensee (a medical center) reported that a patient received more dose than prescribed during a cervical treatment on 11/14/2022. The incident involved a 327.45 GBq (8.85 Ci) Ir -

192 source and a high dose rate (HDR) unit. The patient was scheduled to receive five fractions of 600 cGy (rad) each, for a total of 3,000 cGy (rad). However, the medical physicist misread the prescription and administered the full 3,000 cGy (rad) during the initial treatment. As of 11/15/2022, the patient had not been notified. The patient was scheduled to return on 11/16/2022 for the next treatment. Going forward, the licensee will have one person perform the treatment plan in one p lanning system and another person perform a verification plan in another treatment planning system. The licensee developed a generic table of expected treatment times based on dose and distance of treatment from the sources. The licensee also checked with the manufacturer to determine if software or firmware updates were available for the HDR unit. The Tennessee Department of Environment & Conservation is tracking the incident as number TN-22-069.

Item Number 230065 - The licensee (a university medical center) reported that a patient received a Y-90 microsphere treatment to the wrong lobe of the liver on 2/13/2023. The patient was prescribed to receive 1.32 GBq (35.74 mCi) to the right lobe of the liver for a dose of 5,757 cGy (rad). However, an activity of 1.35 GBq (36.48 mCi) was administered to the left lobe of the liver for a dose of 10,682 cGy (rad). That dose was within 20% of the dose that would have been prescribed to the left lobe in two weeks, according to the physician. The patient was notified of the incident on 2/13/2023. The Radiologist reviewed the treatment as delivered and stated that the medical event was of no clinical significance in terms of complications and communicated that information to the patient on 2/14/2023. The cause of the event was human error and corrective actions included procedure modifications and personnel training. The microsphere procedure was updated to require the nuclear medical technologist to read out the lobe for treatment on the written directive when delivering the dose. The physician is also required to review the treatment just prior to starting the procedure.

Item Number 230101 - The licensee (a university medical center) reported that Y-90 microsphere doses were reversed during a patient's treatment of two liver segments on 2/27/2023. When the physician asked for the first dose, the second dose was brought. After the dose was verbally read out, the physician connected the dose and administered it. The patient was prescribed an activity of 0.8 GBq (21.62 mCi) for a dose of 7,995 cGy (rad) to one segment, but was administered an activity of 1.93 GBq (52.16 mCi) for a dose of 47,470 cGy (rad). The other segment was prescribed an activity of 1.93 GBq (52.16 mCi) for a dose of 47,470 cGy (rad), but was administered an activity of 0.8 GBq (21.62 mCi) for a dose of 7,995 cGy (rad). The cause was determined to be human error. Corrective actions included instituting a radiation dosing education program to include event background and call -back procedures prior to a dose being administered. In addition, personnel will receive training on the program.

Item Number 230255 - The licensee (a medical center) reported a medical event involving a high dose rate brachytherapy treatment on 6/14/2023. The authorized user intended for 1,500 cGy (rad) to be delivered in three separate fractions, each at 500 cGy (rad). However, the treatment was planned and delivered in a single fraction. The incident was discovered the same day (6/14/2023). The 1,500 cGy (rad) was delivered to the keloid skin surface. The authorized user informed the referring physician and patient.

Follow-up with the patient was planned. The Washington State Department of Health is tracking the incident as number WA-23-009.

14 Item Number 230291 - The licensee (a medical center) reported that an HDR intravascular brachytherapy (IVB) treatment was delivered to the wrong treatment site on 7/11/2023. The incident involved an IVB device containing a 3.62 GBq (97.84 mCi) Sr -90 source train. The patient was prescribed a dose of 2,300 cGy (rad) at a depth of 2 mm from the catheter surface to the patient's left circumflex artery. During treatment, the i nterventional cardiologist used fluoroscopy to confirm that the source train had arrived at the intended treatment site. Following the treatment, the i nterventional cardiologist reviewed the fluoroscopic images and reported that he could not actually verify the location of the source on the images. The prescribing physician determined that the source failed to reach the circumflex and instead provided the prescribed dose to another part of the vasculature proximal to the treatment location. This event was caused by the quality and visual complexity of the fluoroscopic images (due to the presence of brachytherapy equipment, interventional equipment, and pre -existing medical devices). The patient and referring physician were notified of this event on 7/11/2023. No permanent damage to any of the patient's organs is expected. Corrective actions included training and procedure modifications to better identify the source location during treatment.

Item Number 230329 - The licensee (a medical center) reported radiation dose to the wrong segments of the patient's liver during microsphere treatment on 6/29/2023. The patient was prescribed to receive 1.41 GBq (38 mCi) of Y-90 activity to segment IV of the patient's liver. Post therapy imaging revealed that part of the activity was taken up by different segments of the patient's liver, in addition to the segment specified in the written directive. The incident resulted in a dose greater than 50 cSv (rem) and greater than 50% of the expected dose to the unintended areas. The licensee stated that the primary cause of the incident was probably due to hepatic artery flow dynamics. There was no anticipated effect on the patient.

Item Number 230341 - The licensee (a university medical center) reported that a patient scheduled to receive treatment to the right lobe of the liver on 7/28/2023 received the dose to the left lobe of the liver.

The incident was identified during imaging performed on 8/16/2023. Approximately 3.07 GBq (83 mCi) of Y-90 microspheres were delivered, resulting in a dose of 13,000 cGy (rad) to the wrong treatment site.

The patient and referring physician were notified of the event. Future treatment of the left lobe of the liver was planned, but not under this written directive. The Ohio Department of Health initiated an investigation.

Events of Interest Item Number 230136 - The licensee (a medical center) reported that a patient was administered a therapeutic activity of 1.4 GBq (37.9 mCi) of Y -90 microspheres to the right lobe of the liver instead of the intended 0.407 GBq (11 mCi) in a two-step successive administration per the written directive. The patient and referring physician were notified. The technologist drew an activity of 2.23 GBq (60.3 mCi) into the vial instead of 0.223 GBq (6.03 mCi) per the written directive for the first dose of an intended two-step successive administration of up to 0.407 GBq (11 mCi). The actual stasis administration was 1.4 GBq (37.9 mCi), which was the activity delivered to the right lobe of the liver. No further administration to the patient occurred. The licensee 's RSO was contacted by Massachusetts Radiation Control Program (RCP) on 3/29/2023 to discuss the facility's immediate corrective actions. RCP recommended that the technologist responsible for the event not be allowed to perform any further therapeutic or diagnostic procedures due to their failure to follow procedures and written directives. The RSO agreed. RCP performed a special inspection on 4/4/2023. Discussion with all key individuals involved in the administration determined that the root cause was a lack of a standardized written Nuclear Medicine policy/procedure for microsphere administration to verify the dose against the patients prescription in the written directive. Contributing factors included failure to verify the activity when the authorized user had doubts, failure to notice that the pre-implantation measurement for the prepared activity was higher than the expected reading, and the activity was drawn by a Nuclear Medicine technologist inexperienced with microsphere treatment procedures without a second verification. One violation was cited in accordance with the special inspection for written procedures failing to provide high confidence that the medical administration would be performed in accordance with the written directive. The licensee submitted a 15 -

15 day written report that contained corrective actions. Corrective actions included formalizing staff retraining specific to microsphere therapies for all Nuclear Medicine and Health Physics staff, revising the written Nuclear Medicine policy/procedure for microsphere treatments, establishing a second verification of the prepared dose, building a spreadsheet to be used by the Nuclear Medicine staff to perform calculations for volume determination, and developing a chart of the expected measurement for pre-implantation for the known amount of activity.

Item Number 230365 - The licensee (a medical center) reported that a patient was prescribed 1,800 cGy (rad) in three fractions using a high dose rate (HDR) unit, a 2.5 cm diameter vaginal cylinder, and a 192.4 GBq (5.2 Ci) Ir-192 source. After the start of the first fraction, the patient notified the authorized user and authorized medical physicist that she thought the cylinder was in the wrong place. The administration was stopped at 111 seconds into the treatment and the licensee d iscovered that the cylinder was placed into the rectum instead of the vagina. Arizona Department of Health Services requested additional information and continued to investigate the incident.

Embryo/Fetus or Nursing Child Dose Events - AOs or Potential AOs Doses to an embryo/fetus or nursing child are reportable per 10 CFR 35.3047. By definition, these events are not medical events (reportable per 10 CFR 35.3045) and are captured in NMED as Other events.

However, it is appropriate to also discuss these events in this section. One of these events occurred in FY23.

Item Number 230039 - The licensee (a university medical center) reported that an embryo/fetus received a radiation dose when a patient who was unknowingly pregnant was administered 1.11 GBq (30 mCi) of I-131 on 10/26/2022. The patient was subsequently determined to be 11 weeks pregnant at the time of treatment. The physicist determined that the fetus received 5 cSv (rem). The licensee had a policy for pregnancy testing in place. Two areas of the hospital thought that the other area had taken care of that requirement. The licensee changed the policy to make sure this does not happen again. Louisiana Department of Environmental Quality completed an investigation. The unborn embryo/fetus was assigned a 5 cSv (rem) exposure.

2.3.3 Events Recently Added to NMED That Occurred Prior to FY23 Three MED events and no embryo/fetal dose events were recently added to NMED that occurred prior to the current fiscal year and had not been included in any previous annual report. None of the MED e vents were considered significant. Note that this data may differ from the associated Appendix D grap h, which displays the number of events added and subtracted from specific years within the most recent 10-year period, including events moved between years due to changes in the recorded event date.

Significant Events - AOs or Potential AOs None Events of Interest Item Number 220186 - The licensee (a university medical center) reported a medical event involving two patients receiving high dose rate (HDR) treatments on 4/8/2022. The event involved an HDR unit with a 370 GBq (10 Ci) Ir-192 source. The event resulted after an HDR radiation therapist replaced a source transfer tube with one that was 123 mm too long. Because the treatments were planned with shorter source transfer tubes, the source did not extend all the way to the intended treatment locations. Both patients were prescribed four fractions of 700 cGy (rad), for a total dose of 2,800 cGy (rad). Only fraction two was affected for Patient A. Patient A was administered 79.1% of the prescribed dose to the intended vaginal target tissue during that fraction. In total, Patient A was administered 2,246 cGy (rad) to the intended tissue during the four fractions or 80.2% of the prescribed 2,800 cGy (rad). Only fraction four was affected for Patient B. Patient B was administered 54.4% of the prescribed dose to the intended vaginal target tissue during that fraction. In total, Patient B was administered 2,419 cGy (rad) to the intended tissue during the four fractions or 86.4% of the prescribed 2,800 cGy (rad). Patient B also received a dose of 700 cGy (rad) to unintended vaginal tissue during fraction four that was not expected.

16 Patient B also received a dose greater than expected to the rectum during that fraction; 5,240 cGy (rad) which was 48% greater than the expected 3,540 cGy (rad). The total dose administered to the rectum during the four fractions exceeded the expected dose by 15.4%. The source transfer tube length error was discovered on 4/13/2022 when another HDR radiation therapist was getting ready for an HDR treatment.

No HDR treatments had occurred since 4/8/2022. The two patients and their referring physicians were notified on 4/14/2022. The California Health and Human Services Agency investigated the incident. The incidents were caused by a lack of training and not following written procedures involving source transfer tube replacement. Corrective actions implemented by the licensee included modification to HDR procedures and personnel training. The procedure for replacement of the catheter is now explicitly included in the initial and annual training for radiation therapists.

Embryo/Fetus or Nursing Child Dose Events - AOs or Potential AOs None

17 2.4 Radiation Overexposure 2.4.1 Ten-Year Data Figure 4 displays the annual number and trend of EXP events that occurred during the 10-year period.

The trend analysis determined that the data does not represent statistically significant trends in the number of events (indicated by the absence of trendlines ).

20

15

12 11 10 10 9 9 9 8 8 7

5

2

0 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023

Fiscal Year

NRC Agreement State Total

Figure 4. Radiation Overexposure Events (8 5 total)

The significance of individual EXP events may be determined by the CFR reporting requirement applicable to the event. For example, an event that is required to be immediately reported is typically more significant than an event with a 30-day reporting requirement. For this report, events requiring immediate or 24-hour reporting are considered significant. Events possessing one or more unusual aspects, but that do not meet the significant event threshold, are considered events of interest.

Table 6 displays the number of events based on the different reporting requirement timeframes. Note that each event is counted only once. If an event involved exposures that were reportable in more than one timeframe, the event is counted in only the most restrictive timeframe.

18 Table 6. EXP Events Classified by CFR Reporting Requirement Fiscal Year 201 4 201 5 2016 201 7 201 8 201 9 2020 202 1 202 2 202 3 Total

Immediate 0 0 1 0 1 0 1 0 0 1 4 24-Hour 3 4 1 2 3 4 0 0 2 2 21

30-Day 8 5 8 6 5 8 6 2 7 5 60

Total 11 9 10 8 9 12 7 2 9 8 85

2.4.2 FY23 Data Eight EXP events occurred in FY23, three of which were considered significant.

Significant Events - Immediate Reporting Item Number 230420 - The licensee (a radiography company) reported that a 2.35 TBq (63.6 Ci) Ir -192 source disconnected from a radiography exposure device on 9/26/2023. The licensee stated that the drive cable was not broken and believed that the incident may have involved a misconnect. The trainee did not have his alarming dosimeter turned on and he did not have his radiation survey meter close by. He believed the source was back in the shielding and he continued to work. He replaced the film, repositioned the tip of the guide tube, and cranked the source back out (although it was already out). He repeated those steps a total of four times before he noticed that the source lock indicator was not in the shielded position. The trainee then checked his self-reading dosimeter and found it off scale. He immediately reported the incident to the radiographer trainer. The radiographer expanded the boundary, maintained security, and waited for the RSO to arrive. Source retrieval was performed by the RSO. The licensee took the trainee to a medical facility for blood tests. Texas Department of State Health Services (DSHS) recommended that the licensee send bloodwork to REAC/TS. DSHS also asked the licensee to take daily pictures of the trainees hands. The trainees dosimetry badge was sent for overnight processing, but it was determined that he had left his dosimetry badge in the truck during operations. An experienced consultant was hired by the licensee. The film for the first two shots came out as expected.

However, the film for the last four shots came out black, indicating that the source was near the film long enough to be overexposed. That indicated the source became disconnected after the second shot. Based upon measured times and distances during re -enactment, a whole-body exposure of 38 cSv (rem) to the trainee was calculated. The estimated exposure to each hand was calculated to be 18 cGy (rad). The trainer was 50 feet away during the event and his radiation dose was 0.05 mSv (5 mrem). This event is also classified as an EQP event and as a Potential Abnormal Occurrence.

Significant Events - Within 24-Hour Report ing Item Number 220536 - The licensee (a radiography company) reported that an overexposure event occurred on 12/14/2022. Three radiographers were working at a remote refinery using a radiography exposure device and a 1.12 TBq (30.4 Ci) Co-60 source. The exposure time for each radiograph was two minutes. The distance from the source to the pipe was two feet. During the first exposure, one radiographer was between the source and the pipe being tested. The radiographer stayed in that area for about one minute. The radiographer operating the crank assembly was standing behind a brick wall and was unaware of the radiographer in the area. The radiographer operating the crank assembly thought that the other radiographers had cleared the area and it was safe to perform operations. The radiographer that received the exposure stated that the noise in the area prevented them from hearing their alarming rate meter. That radiographer's self-reading dosimeter was off scale. All three radiographer's dosimeters were sent for processing. The licensee's RSO stated that their calculations indicated that the exposed radiographer could have received 7 cSv (rem) from the incident. All three radiographers were removed from radiography duties. The licensee received the dosimeter reading for the exposed radiographer. The

19 deep dose equivalent (DDE) was 5.45 cSv (rem), bringing the radiographer's total DDE for the year to 5.662 cSv (rem). The Texas Department of State Health Services (DSHS) requested that the licensee determine if the dosimeter was worn in the highest exposure field during the incident. The licensee conducted reenactments of the event and found that the individual was wearing the dosimeter badge at his hip, which was a few feet below the collimator. Therefore, the closest part of the individual's body to the source was his lower back for about 20 seconds. Based on this, the licensee determined on 12/20/2022 that the radiation exposure to the individual was 5.515 cSv (rem). The individual's DDE for the year 2022 was determined to be 5.527 cSv (rem). Corrective actions taken by the licensee included procedure modifications. As of 12/22/2022, this incident had a final INES Rating Level of 2.

Item Number 230122 - The licensee (a radiography company) reported a possible radiation overexposure to a radiographer. The incident occurred on 3/21/2023 and involved a radiography exposure device and a 2.96 TBq (80 Ci) Ir-192 source. The industrial radiography crew was working on a pipeline. The radiographer was not wearing his dosimetry badge, pocket ion chamber, or rate alarm meter when he realized that the radiation source had not been cranked back into the shielded exposure device and was out to the end of the source guide tube in the collimator. The radiographer had blood work performed to send to REAC/TS for testing. The calculated radiation exposure ranged from 1.8 to 21 cSv (rem). The radiography source was subsequently secured and properly shielded within the exposure device.

Louisiana Department of Environmental Quality performed an investigation. The radiographer was assigned a 9.816 cSv (rem) whole body dose, with 3.59 cSv (rem) to his left hand, and 11.6 cSv (rem) to his right hand. Corrective actions taken by the licensee included terminating employment of the radiographer for not following company operating and emergency procedures, generating a company-wide safety alert via email, holding a company-wide quarterly safety meeting for radiographers and the operations manager, and reviewing the incident again during annual radiation protection/security refresher training at the end of the year.

Events of Interest None 2.4.3 Events Recently Added to NMED That Occurred Prior to FY23 Five EXP events were recently added to NMED that occurred prior to the current fiscal year and had not been included in any previous annual report. None of the RLM events were considered significant. Note that this data may differ from the associated Appendix D graph, which displays the number of events added and subtracted from specific years within the most recent 10-year period, including events moved between years due to changes in the recorded event date.

Significant Events - Immediate Reporting None Significant Events - Within 24-Hour Report ing None Events of Interest Item Number 220368 - The licensee (a radiological equipment manufacturer) reported that individuals/employees were exposed to radioactive material. During a radioactive material release incident on 8/15/2022, the continuous air monitoring system located in a l aboratory alarmed. All individuals immediately exited the laboratory per established protocol. Nasal smears were collected and counted for six laboratory personnel. The results for five personnel were below the facility's 500 dpm threshold. The sixth individual produced a nasal smear result of 725 dpm in the left nostril and 781 dpm in the right nostril. That individual was instructed to blow their nose twice and a second nasal smear test was performed. The second nasal smear test revealed 27 dpm in the left nostril and 30 dpm in the right.

Blank samples that were counted along with the nasal smears were 39 and 7 dpm, respectively. The affected individual was removed from working with radioactive material and began a 24-hour bioassay collection. A root cause investigation into the alarm and positive nasal smears was initiated. The air

20 monitor filter paper was replaced and the activity displayed on the continuous air monitor system returned to normal levels, indicating that the cause of the alarm was a very short duration event. New York Department of Health (DOH) contacted REAC/TS to independently review the nasal smear readings. The review revealed a likely radiation overexposure to one worker who was advised to seek medical treatment. Further site investigation identified a defective machine utilized in producing smoke detectors with Am-241 foil. The one worker believed to be overexposed had been using that machine and had to repeatedly open the fume hood to keep the machine operational. DOH took administrative action to halt production activities, require modification to the radiation safety program, enhance oversight of the licensee through increased inspection frequency, provide specific conditions requiring immediate notification, require an independent safety analysis and adoption of recommendations from these findings, and multiple follow-up site visits by inspection staff to verify progress and status of decontamination and corrective actions. Investigation revealed that several workers had elevated radiation exposures and one worker had exceeded occupational limits for committed dose equivalent (CDE) to bone surfaces with an exposure of 56 cSv (rem). It was found that the licensee had failed to calculate CDE and committed effective dose equivalent (CEDE) from collected bioassay data from 2019 to the date of the incident.

DOH requested that the licensee utilize a third-party certified health physicist consultant to evaluate the collected bioassay data for all workers. The one worker with the overexposure from this incident was found to have consistently exceeded the occupational dose limits for CDE to bone surfaces for calendar years 2019 with 115 cSv (rem), 2020 with 51 cSv (rem), and 2021 with 51 cSv (rem). Additionally, one previous worker that left employment of the licensee in 2022 received 76 cSv (rem) CDE to bone surfaces. DOH followed up on the computational methods used by the consultant to clarify and potentially modify the internal exposures calculated. Additionally, significant Am-241 contamination was found on floors, tables, walls, light fixtures, and specific equipment. The highest gross alpha measurement noted was 93,100 dpm/100 cm 2. That was located on the floor near the punch press and adjacent table. The lowest activity concentration was in the floor area. Gross alpha at that location was 250 dpm/100 cm 2 (opposite side of the room). There was a spare roller that had significantly higher amounts at 1,880,000 dpm/100 cm 2. However, that was expected for a piece of equipment used for routine operations. That roller was stored in the restricted processing area. Further directed corrective actions include replacement of equipment, improvement to the air monitoring systems in laboratories, implementation of a respiratory protection plan, enhancement of emergency response plans, restructuring of management and organizational structure of the company, hiring of additional radiation safety technicians, enhancement of training and personnel monitoring programs, and modification to proprietary work procedures to prevent recurrence. DOH and the licensee discussed further investigation and corrective actions. This event is also classified as an RLM event.

21 2.5 Release of Licensed Material or Contamination 2.5.1 Ten-Year Data Figure 5 displays the annual number and trend of RLM events that occurred during the 10- year period.

The trend analysis determined that the data does not represent statistically significant trends in the number of events (indicated by the absence of trendlines).

15

10 10 9 9

8 8 7

6 6 5

5 4

0 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023

Fiscal Year

NRC Agreement State Total

Figure 5. Release of Licensed Material or Contamination Events(72 total)

The significance of individual RLM events may be determined by the CFR reporting requirement applicable to the event. For example, an event that is required to be immediately reported is typically more significant than an event with a 30-day reporting requirement. For this report, events requiring immediate reporting are considered significant. Events possessing one or more unusual aspects, but that do not meet the significant event threshold, are considered events of interest.

Table 7 displays the number of events based on the different reporting requirement timeframes. Note that each event is counted only once. If an event involved exposures that were reportable in more than one timeframe, the event is counted in only the most restrictive timeframe.

22 Table 7. RLM Events Classified by CFR Reporting Requirement Fiscal Year 201 4 201 5 201 6 201 7 201 8 201 9 2020 202 1 202 2 202 3 Total

Immediate 1 1 1 3 1 1 2 0 2 2 14 24-Hour 3 9 8 3 4 6 5 3 3 4 48

30-Day 2 0 0 1 0 2 1 1 1 2 10

Total 6 10 9 7 5 9 8 4 6 8 72

2.5.2 FY23 Data Eight RLM events occurred in FY23, two of which were considered significant.

Significant Events - Immediate Reporting Item Number 230337 - A private individual reported that a powder being sold by an online marketplace contained Th-232. New Jersey Department of Environmental Protection (DEP) followed up with a site investigation and confirmed that Th-232 was present. The private individual stated that the powder had been mixed into paint, which was used on the walls of his basement and bathroom. DEP visited the seller's residence on 7/8/2023 to perform an interview and contamination survey. The survey confirmed the presence of alpha and beta contamination in the residence. A sample of the powder was also collected and sent for gamma spectrometry analysis by a certified laboratory. Results of the analysis were received on 8/14/2023 and indicated concentrations of Th-232 at 547.6 Bq/g (14,800 pCi/g). The exact total activity is unknown, but a preliminary estimate indicated the activity would exceed five times the lowest ALI for Th-232 at 185 Bq (0.005 µCi).

Item Number 230428 - The licensee (a university medical center) reported that an I -125 localization seed in breast tissue was inadvertently transected during processing by p athology personnel in a laboratory on 9/28/2023. The seed contained an activity of 6.25 MBq (169 µCi). Two staff members were involved and they were told to sequester in the room until personnel from Radiation Safety could respond. Radiation Safety personnel performed surveys to determine the extent of contamination. No personnel contamination was observed. The laboratory was determined to be free of contamination. All contamination was discovered in waste material and on the breast tissue samples. The transected seed was contained. Radiation Safety took possession of the damaged seed and all radioactive waste. At the time of reporting, it was estimated that approximately 50% of the activity was lost to open contamination.

Workers had bioassays performed for thyroid uptake and all returned negative. The cause of the event was human error. Radiation Safety helped to safely process the contaminated breast tissue to ensure there was no additional exposure risk. The authorized user was notified of the event. Pennsylvania Department of Environmental Protection planned to perform a reactive inspection. This event is also classified as an EQP and LKS event.

Events of Interest None 2.5.3 Events Recently Added to NMED That Occurred Prior to FY23 Two RLM event s were recently added to NMED that occurred prior to the current fiscal year and had not been included in any previous annual report. Neither of the RLM events were considered significant. Note that this data may differ from the associated Appendix D graph, which displays the number of events added and subtracted from specific years within the most recent 10-year period, including events moved between years due to changes in the recorded event date.

Significant Events - Immediate Reporting None

23 Events of Interest Item Number 220368 - The licensee (a radiological equipment manufacturer) reported that individuals/employees were exposed to radioactive material. During a radioactive material release incident on 8/15/2022, the continuous air monitoring system located in a l aboratory alarmed. All individuals immediately exited the laboratory per established protocol. Nasal smears were collected and counted for six laboratory personnel. The results for five personnel were below the facility's 500 dpm threshold. The sixth individual produced a nasal smear result of 725 dpm in the left nostril and 781 dpm in the right nostril. That individual was instructed to blow their nose twice and a second nasal smear test was performed. The second nasal smear test revealed 27 dpm in the left nostril and 30 dpm in the right.

Blank samples that were counted along with the nasal smears were 39 and 7 dpm, respectively. The affected individual was removed from working with radioactive material and began a 24-hour bioassay collection. A root cause investigation into the alarm and positive nasal smears was initiated. The air monitor filter paper was replaced and the activity displayed on the continuous air monitor system returned to normal levels, indicating that the cause of the alarm was a very short duration event. New York Department of Health (DOH) contacted REAC/TS to independently review the nasal smear readings. The review revealed a likely radiation overexposure to one worker who was advised to seek medical treatment. Further site investigation identified a defective machine utilized in producing smoke detectors with Am-241 foil. The one worker believed to be overexposed had been using that machine and had to repeatedly open the fume hood to keep the machine operational. DOH took administrative action to halt production activities, require modification to the radiation safety program, enhance oversight of the licensee through increased inspection frequency, provide specific conditions requiring immediate notification, require an independent safety analysis and adoption of recommendations from these findings, and multiple follow-up site visits by inspection staff to verify progress and status of decontamination and corrective actions. Investigation revealed that several workers had elevated radiation exposures and one worker had exceeded occupational limits for committed dose equivalent (CDE) to bone surfaces with an exposure of 56 cSv (rem). It was found that the licensee had failed to calculate CDE and committed effective dose equivalent (CEDE) from collected bioassay data from 2019 to the date of the incident.

DOH requested that the licensee utilize a third-party certified health physicist consultant to evaluate the collected bioassay data for all workers. The one worker with the overexposure from this incident was found to have consistently exceeded the occupational dose limits for CDE to bone surfaces for calendar years 2019 with 115 cSv (rem), 2020 with 51 cSv (rem), and 2021 with 51 cSv (rem). Additionally, one previous worker that left employment of the licensee in 2022 received 76 cSv (rem) CDE to bone surfaces. DOH followed up on the computational methods used by the consultant to clarify and potentially modify the internal exposures calculated. Additionally, significant Am-241 contamination was found on floors, tables, walls, light fixtures, and specific equipment. The highest gross alpha measurement noted was 93,100 dpm/100 cm 2. That was located on the floor near the punch press and adjacent table. The lowest activity concentration was in the floor area. Gross alpha at that location was 250 dpm/100 cm2 (opposite side of the room). There was a spare roller that had significantly higher amounts at 1,880,000 dpm/100 cm 2. However, that was expected for a piece of equipment used for routine operations. That roller was stored in the restricted processing area. Further directed corrective actions include replacement of equipment, improvement to the air monitoring systems in laboratories, implementation of a respiratory protection plan, enhancement of emergency response plans, restructuring of management and organizational structure of the company, hiring of additional radiation safety technicians, enhancement of training and personnel monitoring programs, and modification to proprietary work procedures to prevent recurrence. DOH and the licensee discussed further investigation and corrective actions. This event is also classified as an EXP event.

24 2.6 Leaking Sealed Sources 2.6.1 Ten-Year Data Figure 6 displays the annual number and trend of LKS events that occurred during the 10-year period.

The trend analysis determined that the NRC-regulated events represent a statistically significant decreasing trend (indicated by the trendline). However, the Agreement State-regulated and Total events do not represent statistically significant trend s (indicated by the absence of trendline s).

45

30 30 27 27 28 26

22 19 19 18

15 11

0 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023

Fiscal Year

NRC Agreement State Total

Figure 6. Leaking Sealed Source Events(227 total)

It is not possible to discern the significance of LKS events strictly from the CFR reporting requirements (as in Sections 2.4 and 2.5). There are essentially no immediate or 24-hour reporting requirements for leaking sources. The exception is 10 CFR 39.77(a), which is an immediate report to the NRC Regional office of a ruptured well logging source. Therefore, event significanceis determined on an event-by-event basis based on the severity of the event (e.g., significant exposure to workers, members of the public, and/or the environment). Events possessing one or more unusual aspects, but that do not meet the significant event threshold, are considered events of interest.

2.6.2 FY23 Data Thirty LKS events occurred in FY23, none of which were considered significant.

Significant Events None Events of Interest Item Number 230428 - The licensee (a university medical center) reported that an I -125 localization seed in breast tissue was inadvertently transected during processing by p athology personnel in a laboratory on

25 9/28/2023. The seed contained an activity of 6.25 MBq (169 µCi). Two staff members were involved and they were told to sequester in the room until personnel from Radiation Safety could respond. Radiation Safety personnel performed surveys to determine the extent of contamination. No personnel contamination was observed. The laboratory was determined to be free of contamination. All contamination was discovered in waste material and on the breast tissue samples. The transected seed was contained. Radiation Safety took possession of the damaged seed and all radioactive waste. At the time of reporting, it was estimated that approximately 50% of the activity was lost to open contamination.

Workers had bioassays performed for thyroid uptake and all returned negative. The cause of the event was human error. Radiation Safety helped to safely process the contaminated breast tissue to ensure there was no additional exposure risk. The authorized user was notified of the event. Pennsylvania Department of Environmental Protection planned to perform a reactive inspection. This event is also classified as an RLM and EQP event.

2.6.3 Events Recently Added to NMED That Occurred Prior to FY23 One LKS event was recently added to NMED that occurred prior to the current fiscal year and had not been included in any previous annual report. This event was not considered significant. Note that this data may differ from the associated Appendix D graph, which displays the number of events added and subtracted from specific years within the most recent 10-year period, including events moved between years due to changes in the recorded event date.

Significant Events None Events of Interest Item Number 220482 - The licensee (a medical equipment manufacturer) reported a leaking Cs -131 brachytherapy source. There were 105 seeds in the order, each with an internal activity of 141.71 MBq (3.83 mCi). A customer detected contamination on equipment used during a procedure involving Cs -131 seeds. The customer was not initially able to identify the radionuclide of the contamination, but was able to perform a half-life estimation using dose measurements. Upon receipt of the order of Cs -131 seeds, no contamination was found in the non-sterile mick pig. The order was sterilized prior to use. The customer then inserted the seeds into needles. There was no evidence of contamination up to that point. However, after the implant, surveys of material in the operating room found contamination on three spent mick cartridges, eight needles, a piece of sterile cloth, water bucket/water, and part of the mick applicator. The contamination levels were extremely low (no values provided). All of the implanted seeds were accounted for by post operative CT scan and they did not believe that they had severed a seed during the implant procedure. There was no contamination found on the doctor's gloves or on or near the patient. All of the licensee's seed welding and leak test batch records indicated negative results (no removable contamination). Assay of the seeds in the cleanroom involved the use of vibratory bowls and other equipment that was surveyed following the completion of the order; no contamination was reported. As part of the shipping process, orders are surveyed using smears to check for removable contamination; no contamination was identified. The licensee stated that it would be unlikely that compromised seeds or loose contamination on the seeds, mick applicators, mick pig, labels, or packaging was shipped from their facility. The licensee believed that the customer inadvertently broke or cut a seed during the implant procedure. A thorough investigation was performed. In conclusion, the licensee found that it is possible that if an unacceptable weld passed through their QC check points, it could later become compromised after shipping by handling at the customer site. There is no way of telling for certain if that is what caused the contamination at the customer site since the seeds from the order were not available for examination.

Based on radiation readings given by the customer, it is most probable that only one seed was compromised. The customer stated that after gathering all of the contaminated material in a single container, the exposure rate measurement was 0.7 mR/hr at six inches. That would translate to approximately 8.33 kBq (225 nCi). The licensee made improvements to their inspection process and procedures to clarify in greater detail the inspection expectations and shore up possible weak points.

26 Corrective actions included increasing the acceptable quality limit (AQL) sampling plan for the inspection of cans, updating specification for cans to capture better images for visual inspection, updating specification for lids to include enhanced visual and physical examination requirements, and updating procedures to further clarify lid inspection acceptance/rejection criteria. This event is also classified as an EQP event.

27 2.7 Equipment 2.7.1 Ten-Year Data Figure 7 displays the annual number and trend of EQP events that occurred during the 10-year period.

The trend analysis determined that the NRC-regulated and Total events represent statistically significant decreasing trends (indicated by the trendlines). However, the Agreement State-regulated events do not represent a statistically significant trend (indicated by the absence of a trendline).

250

200

150 137 141 140 138 130 108 108 109 116

100 93

50

0 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023

Fiscal Year

NRC Agreement State Total

Figure 7. Equipment Events (1, 220 total)

It is not possible to discern the significance of EQP events strictly from the CFR reporting requirements (as in Sections 2.4 and 2.5) because essentially all of the CFRs associated with EQP events require reporting within 24-hours. Therefore, event significance will be determined on an event-by-event basis based on the severity of the event (e.g., significant exposure to workers, members of the public, and/or the environment). Events possessing one or more unusual aspects, but that do not meet the significant event threshold, are considered events of interest.

2.7.2 FY23 Data One hundred sixteen EQP events occurred in FY23, three of which were considered significant.

Significant Events Item Number 230358 - The licensee (a mining company) reported that a 1.85 GBq (50 mCi) Cs -137 source had fallen out of a pipe flow density gamma gauge at their facility in Bartow, Florida. The source was found on the ground adjacent to the gauge on 8/28/2023. The cause is believed to be equipment vibration. The area was secured and restricted. The licensee had no radiological survey instruments.

Florida Bureau of Radiation Control (BRC) responded to the site to investigate and secure the source. The BRC inspector returned to the site on 8/29/2023 and verified that a radiological services provider had

28 returned the source to the shielded position within the gauge. The gauge remained out -of-service pending removal from the piping system. BRC verified that the gauge manufacturer sold the gauge to the licensee, but the sale was not reported to BRC by any party. This event is also classified as an LAS event.

Item Number 230420 - The licensee (a radiography company) reported that a 2.35 TBq (63.6 Ci) Ir -192 source disconnected from a radiography exposure device on 9/26/2023. The licensee stated that the drive cable was not broken and believed that the incident may have involved a misconnect. The trainee did not have his alarming dosimeter turned on and he did not have his radiation survey meter close by. He believed the source was back in the shielding and he continued to work. He replaced the film, repositioned the tip of the guide tube, and cranked the source back out (although it was already out). He repeated those steps a total of four times before he noticed that the source lock indicator was not in the shielded position. The trainee then checked his self-reading dosimeter and found it off scale. He immediately reported the incident to the radiographer trainer. The radiographer expanded the boundary, maintained security, and waited for the RSO to arrive. Source retrieval was performed by the RSO. The licensee took the trainee to a medical facility for blood tests. Texas Department of State Health Services (DSHS) recommended that the licensee send bloodwork to REAC/TS. DSHS also asked the licensee to take daily pictures of the trainees hands. The trainees dosimetry badge was sent for overnight processing, but it was determined that he had left his dosimetry badge in the truck during operations. An experienced consultant was hired by the licensee. The film for the first two shots came out as expected.

However, the film for the last four shots came out black, indicating that the source was near the film long enough to be overexposed. That indicated the source became disconnected after the second shot. Based upon measured times and distances during re -enactment, a whole-body exposure of 38 cSv (rem) to the trainee was calculated. The estimated exposure to each hand was calculated to be 18 cGy (rad). The trainer was 50 feet away during the event and his radiation dose was 0.05 mSv (5 mrem). This event is also classified as an EXP event and as a Potential Abnormal Occurrence.

Item Number 230428 - The licensee (a university medical center) reported that an I -125 localization seed in breast tissue was inadvertently transected during processing by p athology personnel in a laboratory on 9/28/2023. The seed contained an activity of 6.25 MBq (169 µCi). Two staff members were involved and they were told to sequester in the room until personnel from Radiation Safety could respond. Radiation Safety personnel performed surveys to determine the extent of contamination. No personnel contamination was observed. The laboratory was determined to be free of contamination. All contamination was discovered in waste material and on the breast tissue samples. The transected seed was contained. Radiation Safety took possession of the damaged seed and all radioactive waste. At the time of reporting, it was estimated that approximately 50% of the activity was lost to open contamination.

Workers had bioassays performed for thyroid uptake and all returned negative. The cause of the event was human error. Radiation Safety helped to safely process the contaminated breast tissue to ensure there was no additional exposure risk. The authorized user was notified of the event. Pennsylvania Department of Environmental Protection planned to perform a reactive inspection. This event is also classified as an LKS and RLM event.

Events of Interest Item Number 220508 - The licensee (a medical center) reported that a patient with squamous cell carcinoma of the cervix only received 1.7% of the prescribed fractionated dose due to an equipment malfunction on 11/16/2022. The patient was implanted with an intracavitary applicator consisting of a 50 mm 45 degree tandem, 35 mm ovoids, and four needles. The patient was prescribed 750 cGy (rad) during their third fraction, but only received 12.7 cGy (rad). The patient treatment time was 405.3 seconds. The incident involved a high dose rate (HDR) afterloader unit with a 329.3 GBq (8.9 Ci) Ir -192 source.

During administration, the HDR unit was unable to detect one of the transfer tubes connecting it to the implanted applicator. That resulted in a partial delivery of the prescribed dose. The HDR unit was only able to deliver the planned dose for the right 35 mm ovoid, totaling 33.3 seconds. The delivered dose was 98.3% less than prescribed for the third fraction. Assessment by the manufacturer's field service engineer

29 determined that the HDR unit's selector assembly should be recalibrated, including lubrication of all brackets on the assembly. Following recalibration of the selector assembly, the HDR unit functioned correctly. Spot checks confirmed normal operation of the HDR unit. The HDR unit reentered clinical service the following day and the patient was successfully treated for their third fraction on 11/21/2022.

The patient finished treatment on 11/23/2022. The Georgia Department of Natural Resources completed their investigation. This event is also classified as an MED event.

Item Number 230108 - The licensee (a university medical center) reported that a patient received less dose than prescribed during a gamma knife treatment on 3/14/2023. The unit malfunctioned after completing only three of the planned 13 shots. The unit displayed an error that could not be resolved by licensee personnel and required a service technician. The treatment was consequently suspended. The prescribed dose was 1,500 cGy (rad). The dose administered was approximately 44.11 cGy (rad), which was 2.9% of that prescribed. The service technician identified a worn sector drive as the cause of the malfunction. This event is also classified as an MED event.

Item number 230166 - The licensee (a medical center) reported that a patient received less dose than prescribed during a high dose rate (HDR) treatment to the cervix on 4/19/2023. The incident involved an HDR remote afterloader unit and a 267.51 GBq (7.23 Ci) Ir -192 source. The applicator had three sections; right partial ring, left partial ring, and tandem. The patient was prescribed four treatments of 500 cGy (rad) each. The first three treatments were administered without issue, but the HDR gave an error message associated with a source retraction issue during the first treatment on 4/12/2023; this issue was resolved without need to implement emergency procedures. During the fourth treatment, the HDR unit functioned properly in treating the right and left rings. After treating the left ring, the HDR unit again gave an error message associated with a source retraction issue and the radiation monitors in the room and above the door indicated that the source did not return to the safe position. As a result, the treatment was stopped; the tandem was not treated. Licensee personnel failed to follow emergency procedures during several unsuccessful attempts to bring the source to the safe position. The applicator was ultimately removed from the patient, the patient was removed from the room, and the room was closed and sealed. The patient received 156 cGy (rad) during the fourth treatment, which is 31.2% of the prescribed 500 cGy (rad). The total dose received from all four treatments was 1,656 cGy (rad), which is 83% of the prescribed 2,000 cGy (rad). Initial radiation exposure estimates for the individuals in the room for the approximately 6 minutes that the source was outside the HDR unit were conservatively estimated to be 10 cSv (rem); these estimates were subsequently revised to 1 cSv (rem) due to calculational errors. However, dosimeters were immediately sent for processing and the actual readings were below the reportable limit; dosimeter readings for the individuals were between 0.02 and 0.87 mSv (2 and 87 mrem). The calculated doses for unbadged individuals in the room were similar. The calculated dose to the patient due to the stuck source was 1.41 cSv (rem) whole body and 7.125 cSv (rem) to the leg. The primary probable cause was the failure of the HDR unit's primary and secondary motors that retract the source back into the shielded position. The source and the A drive (containing both motors) were extracted from the HDR unit and returned to the manufacturer for evaluation on 5/11/2023. The manufacturer found the source cable to be within tolerance, with no kinks, abrasions, damage of any sort, or unusual friction. However, the licensee had used an applicator that was not approved for use with the HDR system. The applicator had an internal transition that, in certain orientations, caused the source capsule to become stuck. Corrective actions included placing the HDR program on hold pending a root cause evaluation, equipment testing, re -

evaluating policies and procedures, and personnel training. This event is also classified as an MED event.

2.7.3 Events Recently Added to NMED That Occurred Prior to FY23 Six EQP events were recently added to NMED that occurred prior to the current fiscal year and had not been included in any previous annual report. None of these events were considered significant. Note that this data may differ from the associated Appendix D graph, which displays the number of events added and subtracted from specific years within the most recent 10-year period, including events moved between years due to changes in the recorded event date.

30 Significant Events None Events of Interest Item Number 160035 - The licensee (a manufacturer) reported the loss and recovery of a process automation beta gauge that contained a 2,590 MBq (70 mCi) Sr -90 source. The loss was discovered during an annual general license self-inspection on 1/20/2016. The licensee believed that the gauge was removed by a local scrap vendor or by an equipment vendor, which had both been on site; both were contacted. Illinois Emergency Management Agency (EMA) responded to the site on the day that the incident was discovered to investigate. The manufacturer was contacted and had no record that the gauge had been returned. A company who does service work for the licensee was also contacted. The licensee believed that a factor in the loss was the equipment being moved to temporary storage at an adjacent property. The licensee modified procedures to no longer allow offsite storage of production equipment containing radioactive material and to better screen all equipment that is removed from service to enhance accounting. The licensee also contracted with a third party to provide routine support and maintenance for all gauges, which should assist in positive accounting. The gauge was subsequently located at a scrap metal recycler on 9/15/2023. The gauge was heavily damaged with the source exposed. EMA responders fabricated shielding and packaged the gauge for return to the licensee. The licensee was responsible for proper disposal through an approved vendor. EMA verified safe and secure storage. The licensee provided documentation on 10/19/2023 that the gauge was appropriately transferred for disposal and provided a negative leak test. This event is also classified as an LAS event.

Item Number 220400 - The licensee (a manufacturer) reported that workers were inadvertently exposed to radiation from a fixed nuclear gauge. On 8/22/2022, the licensee reported that the gauge's source shutter was found stuck open during six-month radiation surveys. The gauge contained a 3.7 GBq (100 mCi) Cs-137 source. The gauge was repaired on 8/25/2022. Source lock-out procedures were implemented on 8/31/2022 to allow a crew to enter and inspect the tank. The gauge was locked out with the source in the unshielded position. A confined entry crew of four workers were exposed for 77 minutes and three workers were exposed for 22 minutes. Estimated radiation exposure calculations indicated the worst-case scenario to be approximately 39.6 mR/hr at one foot. The workers were not stationary inside the tank; they were moving and building a scaffold during their time in the tank at different levels and distances. Preliminary radiation exposure estimates appeared not to exceed public exposure limits. The licensee contacted the Radioactive Material Director on 9/2/2022 regarding the personnel radiation exposures. The Mississippi State Department of Health (DOH) was notified on 9/6/2022. A DOH inspector arrived at the site on 9/7/2022 to investigate. It was determined that none of the workers had radiation training and all were general workers. Dosimeter results from dose reconstruction revealed that no worker exceeded the public dose limits based on the reconstruction performed by the licensee and the gauge manufacturer. All personnel received additional training on proper selection of instrumentation as it was found that the licensee authorized users were using alpha meters to survey for gamma radiation.

Lock-out/tag -out procedures were revised to prevent recurrence as the gauge was not locked out but placed in the open position prior to the workers entering the tank for confined space work.

Item Number 220482 - The licensee (a medical equipment manufacturer) reported a leaking Cs -131 brachytherapy source. There were 105 seeds in the order, each with an internal activity of 141.71 MBq (3.83 mCi). A customer detected contamination on equipment used during a procedure involving Cs -131 seeds. The customer was not initially able to identify the radionuclide of the contamination, but was able to perform a half-life estimation using dose measurements. Upon receipt of the order of Cs -131 seeds, no contamination was found in the non-sterile mick pig. The order was sterilized prior to use. The customer then inserted the seeds into needles. There was no evidence of contamination up to that point. However, after the implant, surveys of material in the operating room found contamination on three spent mick cartridges, eight needles, a piece of sterile cloth, water bucket/water, and part of the mick applicator. The contamination levels were extremely low (no values provided). All of the implanted seeds were accounted

31 for by post operative CT scan and they did not believe that they had severed a seed during the implant procedure. There was no contamination found on the doctor's gloves or on or near the patient. All of the licensee's seed welding and leak test batch records indicated negative results (no removable contamination). Assay of the seeds in the cleanroom involved the use of vibratory bowls and other equipment that was surveyed following the completion of the order; no contamination was reported. As part of the shipping process, orders are surveyed using smears to check for removable contamination; no contamination was identified. The licensee stated that it would be unlikely that compromised seeds or loose contamination on the seeds, mick applicators, mick pig, labels, or packaging was shipped from their facility. The licensee believed that the customer inadvertently broke or cut a seed during the implant procedure. A thorough investigation was performed. In conclusion, the licensee found that it is possible that if an unacceptable weld passed through their QC check points, it could later become compromised after shipping by handling at the customer site. There is no way of telling for certain if that is what caused the contamination at the customer site since the seeds from the order were not available for examination.

Based on radiation readings given by the customer, it is most probable that only one seed was compromised. The customer stated that after gathering all of the contaminated material in a single container, the exposure rate measurement was 0.7 mR/hr at six inches. That would translate to approximately 8.33 kBq (225 nCi). The licensee made improvements to their inspection process and procedures to clarify in greater detail the inspection expectations and shore up possible weak points.

Corrective actions included increasing the acceptable quality limit (AQL) sampling plan for the inspection of cans, updating specification for cans to capture better images for visual inspection, updating specification for lids to include enhanced visual and physical examination requirements, and updating procedures to further clarify lid inspection acceptance/rejection criteria. This event is also classified as an LKS event.

32 2.8 Transportation 2.8.1 Ten-Year Data Figure 8 displays the annual number and trend of TRS events that occurred during the 10-year period. The trend analysis determined that the NRC -regulated, Agreement State-regulated, and Total events represent statistically significant decreasing trends (indicated by the trendline s).

40

30

21

20 18 17 16 15

10 11 11 11

10 8

0 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023

Fiscal Year

NRC Agreement State Total

Figure 8. Transportation Events (138 total)

It is not possible to discern the significance of TRS events strictly from the CFR reporting requirements (as in Sections 2.4 and 2.5). Therefore, event significance will be determined on an event-by-event basis based on the severity of the event (e.g., significant exposure to workers, members of the public, and/or the environment). Events possessing one or more unusual aspects, but that do not meet the significant event threshold, are considered events of interest.

2.8.2 FY23 Data Eight TRS events occurred in FY23, none of which were considered significant.

Significant Events None Events of Interest None.

2.8.3 Events Recently Added to NMED That Occurred Prior to FY23 Two TRS events were recently added to NMED that occurred prior to the current fiscal year and had not been included in any previous annual report. Neither event was considered significant. Note that this data may differ from the associated Appendix D graph, which displays the number of events added and

33 subtracted from specific years within the most recent 10-year period, including events moved between years due to changes in the recorded event date.

Significant Events None Events of Interest None

34 2.9 Other 2.9.1 Ten-Year Data Figure 10 displays the annual number of OTH events that occurred during the 1 0-year period. Because OTH events do not fit a defined criterion that ensures consistency within the data, trending analysis is not performed on this data.

15

12

10

8 7

5 4 4

3 3 3 3 3

0 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023

Fiscal Year

NRC Agreement State Total

Figure 9. Other Events (5 0 total)

It is not possible to discern the significance of OTHevents strictly from the CFR reporting requirements (as in Sections 2.4 and 2.5). Therefore, event significance will be determined on an event-by-event basis based on the severity of the event (e.g., significant exposure to workers, members of the public, and/or the environment). Events possessing one or more unusual aspects, but that do not meet the significant event threshold, are considered events of interest.

2.9.2 FY23 Data Three OTH events occurred in FY23, one of which was considered significant.

Significant Events Item Number 230039 - The licensee (a university medical center) reported that an embryo/fetus received a radiation dose when a patient who was unknowingly pregnant was administered 1.11 GBq (30 mCi) of I-131 on 10/26/2022. The patient was subsequently determined to be 11 weeks pregnant at the time of treatment. The physicist determined that the fetus received 5 cSv (rem). The licensee had a policy for pregnancy testing in place. Two areas of the hospital thought that the other area had taken care of that requirement. The licensee changed the policy to make sure this does not happen again. Louisiana Department of Environmental Quality completed an investigation. The unborn embryo/fetus was assigned a 5 cSv (rem) exposure.

35 Events of Interest Item Number 230152 - The licensee (a medical imaging center) reported a possible radiation overexposure to an embryo/fetus of a declared pregnant woman. The employee was a technical assistant for mobile positron emission tomography/computed tomography (PET/CT) operations and was not directly involved with handling radioactive material. The estimated exposure was 1.145 cSv (rem) DDE for a one-month period. The employee's cumulative exposure was 1.239 cSv (rem) DDE. The licensee's report indicated it was possible that the badge may have been in the PET/CT scanner room during patient scans, but the employee could not recall if that ever happened. The licensee also reported that the chest and control badges showed no elevated readings, only the fetal badge. The licensee's corrective actions included discussing with the employee the importance of making sure the badge is never left in a radiation area, and that the badge is always worn properly for the entire day while at work. Proper storage of badges next to the control badge was also discussed. The South Carolina Department of Health &

Environmental Control performed an on -site investigation on 3/29/2023 and the information obtained during the on-site investigation was consistent with the licensee's written report.

2.9.3 Events Recently Added to NMED That Occurred Prior to FY23 One OTH event w as recently added to NMED that occurred prior to the current fiscal year and had not been included in any previous annual report. This event was not considered to be significant. N ote that this data may differ from the associated Appendix D graph, which displays the number of events added and subtracted from specific years within the most recent 10-year period, including events moved between years due to changes in the recorded event date.

Significant Events None Events of Interest Item Number 230274 - The licensee (a government agency) reported that three employees from the maintenance department gained unauthorized access to the irradiator room by means of a master key not controlled by the Radiation Safety Department. The employees were provided the key by the Director of Facilities, who believed that they were authorized to enter the room despite signage stating that access could only be granted by the Radiation Safety Department. Security responded within five minutes, stopped work, and escorted the three individuals from the room. The licensee conducted an investigation and determined the cause of the event to be inadequate procedures. The licensee instituted corrective actions involving revising procedures, providing training to personnel, and security lock modifications.

The licensee determined that none of the safety equipment was handled, radioactive material was not accessed, and the workers did not receive radiation exposure. The NRC conducted an inspection of the licensee and the event on 2/28/2022.

36 Appendix A

Event Type Descriptions and Criteria

A-1 A-2 Appendix A Event Type Descriptions and Criteria

NMED events covered by this report are divided into the following categories (event tyeps) based on the event reporting requirements defined in 10 CFR. Note that the tables in this appendix do not contain the full text of the applicable CFRs.

Lost/Abandoned/Stolen Material (LAS)

The LAS event type includes those events where licensed radioactive material is lost or found, abandoned or discovered, and stolen or recovered. The radioactive material involved can be sealed or unsealed material, specifically or generally licensed, exempt or non-exempt quantities, involve a licensee or a non-licensee, and can be found anywhere. Abandoned well logging sources are included in this event type.

NMED LAS reportable events are those that meet the reporting requirements of 10 CFR Part 20.2201. If they are in NMED, events that do not meet the 20.2201 reporting requirement thresholds are captured as not-reportable LAS events. Additionally, LAS events involving non-Atomic Energy Act material are captured as not-reportable events if they are in NMED.

All reportable LAS events will be coded as one of the following reporting requirements. For events involving more than one source, the decision of 10 x or 1,000 x the 10 CFR Part 20 Appendix C quantity is based on the aggregate quantity of licensed material.

Table A-1. Primary LAS Reporting Requirements Primary LAS Reporting Requirements Reporting Requirement Summary 20.2201(a)(1)(i) Aggregate activity 1,000 x 10 CFR Part 20 Appendix C quantity 20.2201(a)(1)(ii) Aggregate activity > 10 and < 1,000 x 10 CFR Part 20 Appendix C quantity 39.77(d) Irretrievable well logging source

The following additional (secondary) CFRs will be added as applicable. This should occur infrequently.

For the 10 CFR 37 requirements, the event will instead be coded as OTH if there was no actual theft, sabotage, or diversion of Category 1 or 2 quantities of radioa ctive material.

Table A-2. Secondary LAS Reporting Requirements Secondary LAS Reporting Requirements Reporting Requirement Summary 30.55(c) Theft/diversion of 10 Ci (or 100 Ci per year) of H 3 (not generally licensed).

37.57(a) Unauthorized entry resulted in actual or attempted theft, sabotage, or diversion of a category 1 or category 2 quantity of material.

37.57(b) Suspicious activity related to possible theft, sabotage, or diversion of a category 1 or category 2 quantity of material 37.81(a) A shipment of category 1 quantities of material is lost or missing.

37.81(b) A shipment of category 2 quantities of material is lost or missing.

37.81(c) Actual or attempted theft or diversion (or related suspicious activities) of a shipment of category 1 quantities of material.

37.81(d) Actual or attempted theft or diversion (or related suspicious activities) of a shipment of category 2 quantities of material.

37.81(e) Recovery of any lost or missing shipment of category 1 quantities of material.

37.81(f) Recovery of any lost or missing shipment of category 2 quantities of material.

A-3 39.77(b) Theft or loss of radioactive material, radiation overexposures, excessive levels and concentrations of radiation for events involving well logging operations, and certain other accidents.

40.64(c)(1) Theft/diversion of 15 lb (or 150 lb per year) of source material (uranium or thorium).

73.71(a)(1) Lost shipment of any SNM.

73.App G(I)(a)(1) Actual or attempted theft or unlawful diversion of SNM.

74.11(a) Loss, theft or unlawful diversion (actual or attempted) of SNM or the unauthorized production of enriched uranium.

76.120(a)(2) Loss, other than normal operating loss, of special nuclear material.

76.120(a)(3) Actual or attempted theft or unlawful diversion of special nuclear material.

150.16(b)(1) Actual or attempted theft or unlawful diversion of SNM.

150.17(c)(1) Attempted theft or unlawful diversion of more than 6.8 kg (15 lb) of Uranium or Thorium at any one time or more than 68 kg (150 lb) in any one calendar year.

150.19(c) Theft/diversion of 10 Ci (or 100 Ci per year) of H-3 (not generally licensed). Note:

This requirement is just like 30.55(c) but applies to Agreement States and offshore waters.

A-4 Medical (MED)

MED events are determined and coded per the 10 CFR reporting requirements listed below.

Table A-3. MED Reporting Requirements MED Reporting Requirements Reporting Requirement Summary 35.3045(a)(1)(i)(A) Total dose delivered that differs from the prescribed dose by 20% or more; and differs from the prescribed dose by more than 0.05 Sv (5 rem) EDE, 0.5 Sv (50 rem) to an organ or tissue, or 0.5 Sv (50 rem) SDE to the skin.

35.3045(a)(1)(i)(B) Total dosage delivered that differs from the prescribed dosage by 20% or more or falls outside the prescribed range; and results in a dose that differs from prescribed by more than 0.05 Sv (5 rem) EDE, 0.5 Sv (50 rem) to an organ or tissue, or 0.5 Sv (50 rem) SDE to the skin.

35.3045(a)(1)(i)(C) Fractionated dose delivered that differs from the prescribed dose for a single fraction by 50% or more; and differs from the prescribed dose by more than 0.05 Sv (5 rem) EDE, 0.5 Sv (50 rem) to an organ or tissue, or 0.5 Sv (50 rem) SDE to the skin.

35.3045(a)(1)(ii)(A) Administration of a wrong radioactive drug containing byproduct material or the wrong radionuclide for a brachytherapy procedure that results in a dose that exceeds 0.05 Sv (5 rem) EDE, 0.5 Sv (50 rem) to an organ or tissue, or 0.5 Sv (50 rem) SDE to the skin.

35.3045(a)(1)(ii)(B) Administration of a radioactive drug containing byproduct material by the wrong route of administration that results in a dose that exceeds 0.05 Sv (5 rem) EDE, 0.5 Sv (50 rem) to an organ or tissue, or 0.5 Sv (50 rem) SDE to the skin.

35.3045(a)(1)(ii)(C) Administration of a dose or dosage to the wrong individual or human research subject that results in a dose that exceeds 0.05 Sv (5 rem) EDE, 0.5 Sv (50 rem) to an organ or tissue, or 0.5 Sv (50 rem) SDE to the skin.

35.3045(a)(1)(ii)(D) Administration of a dose or dosage delivered by the wrong mode of treatment that results in a dose that exceeds 0.05 Sv (5 rem) EDE, 0.5 Sv (50 rem) to an organ or tissue, or 0.5 Sv (50 rem) SDE to the skin.

35.3045(a)(1)(ii)(E) Leaking sealed source that results in a dose that exceeds 0.05 Sv (5 rem) EDE, 0.5 Sv (50 rem) to an organ or tissue, or 0.5 Sv (50 rem) SDE to the skin.

35.3045(a)(1)(iii) Dose to the skin, organ, or tissue, other than the treatment site, that exceeds by 0.5 Sv (50 rem) or more and 50% or more the expected dose to that site from the procedure if the administration had been given in accordance with the written directive prepared or revised before administration.

35.3045(a)(2)(i) For permanent implant brachytherapy, the total source strength administered differs by 20% or more from the total source strength documented in the post-implant portion of the written directive, excluding sources that were implanted in the correct site but migrated outside of the treatment site.

35.3045(a)(2)(ii) For permanent implant brachytherapy, the total source strength administered outside of the treatment site exceeds 20% of the total source strength documented in the post-implant portion of the written directive, excluding sources that were implanted in the correct site but migrated outside of the treatment site.

35.3045(a)(2)(iii)(A) For permanent implant brachytherapy, an administration that includes the wrong radionuclide.

35.3045(a)(2)(iii)(B) - For permanent implant brachytherapy, an administration that includes the wrong individual or research subject.

35.3045(a)(2)(iii)(C) For permanent implant brachytherapy, an administration that includes sealed sources implanted directly into a location discontiguous from the treatment site, as documented in the post-implant portion of the written directive.

35.3045(a)(2)(iii)(D) For permanent implant brachytherapy, an administration that includes a leaking sealed source resulting in a dose that exceeds 0.5 Sv (50 rem) to an organ or tissue.

A-5 35.3045(b) Event resulting from patient intervention in which the administration of byproduct material or radiation from byproduct material results in unintended permanent functional damage to an organ or a physiological system, as determined by a physician.

Events are not considered MED events if they involve:

• Only a linear accelerator,

• Doses administered in accordance with a written directive (even if the directive is in error), or

• Patient intervention, unless the event results in unintended permanent functional damage to an organ or physiological system.

Events are considered MED events if, for example, a linear accelerator is used for therapy by mistake instead of a teletherapy unit or a teletherapy unit instead of a linear accelerator.

For purposes of determining whether to categorize an event as MED or EXP, MED events occur to patients only (i.e., those being administered a medical procedure). For example, if a patient receives too much dose during a procedure, the event would be categorized as MED rather than EXP. However, radiation exposure received from a cause other than the patients medical procedure may be categorized as EXP.

A-6 Radiation Overexposure (EXP)

EXP events are determined and coded per the 10 CFR reporting requirements listed below.

Table A-4. EXP Reporting Requirements EXP Reporting Requirements Reporting Requirement Summary 20.2202(a)(1)(i) An individual received a total effective dose equivalent of 25 rem (0.25 Sv) or more.

20.2202(a)(1)(ii) An individual received a lens dose equivalent of 75 rem (0.75 Sv) or more.

20.2202(a)(1)(iii) An individual received a shallow-dose equivalent to the skin or extremities of 250 rad (2.5 Gy) or more.

20.2202(b)(1)(i) Loss of control of material causing or threatening to cause an individual to receive a total effective dose equivalent exceeding 5 rem (0.05 Sv) in a period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

20.2202(b)(1)(ii) Loss of control of material causing or threatening to cause an individual to receive an eye dose equivalent exceeding 15 rem (0.15 Sv) in a period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

20.2202(b)(1)(iii) Loss of control of material causing or threatening to cause an individual to receive a shallow-dose equivalent to the skin or extremities exceeding 50 rem (0.5 Sv) in a period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

20.2203(a)(2)(i) Doses in excess of the occupational dose limits for adults in 20.1201.

20.2203(a)(2)(ii) Doses in excess of the occupational dose limits for a minor in 20.1207.

20.2203(a)(2)(iii) Doses in excess of the limits for an embryo/fetus of a declared pregnant woman in 20.1208.

20.2203(a)(2)(iv) Doses in excess of the limits for an individual member of the public in 20.1301.

20.2203(a)(2)(v) Doses in excess of any applicable limit in the license.

39.77(b) Theft or loss of radioactive material, radiation overexposures, excessive levels and concentrations of radiation for events involving well logging operations, and certain other accidents.

The EXP event type includes all regulatory overexposures of radiation workers or exposures of members of the public to radiation. The overexposure can be external or internal and can be whole body, extremity, skin, lens of the eye, or internal dose. When the overexposure involves multiple individuals or an individual with multiple overexposure types (such as whole body and extremity), the different types of overexposures are entered separately. Note that dosimeters record exposure if improperly stored near a radiation source and, depending on the type of dosimeter, may react as though they are in a radiation field when exposed to heat or humidity.

It is NRC policy to classify only those events that positively involve a personnel overexposure, and not just a dosimeter exposure, as reportable EXP events. For example, either the licensee does not contest the personnel overexposure, or in cases where the licensee does contest the overexposure, the State or NRC determines the event to be personnel overexposure.

EXP limits do not apply to patients receiving medical procedures.

A-7 Release of Licensed Material or Contamination (RLM)

RLM events are determined and coded per the 10 CFR reporting requirements listed below.

Table A-5. RLM Reporting Requirements RLM Reporting Requirements Reporting Requirement Summary 20.2202(a)(2) Release of radioactive material, inside or outside of a restricted area, so that had an individual been present for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, the individual could have received an intake 5 times the ALI.

20.2202(b)(2) Release of material, inside or outside of a restricted area, so that, had an individual been present for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, the individual could have received an intake in excess of 1 ALI.

20.2203(a)(2)(vi) Doses in excess of the ALARA constraints for air emissions established under 20.1101(d).

20.2203(a)(3)(i) Radiation or concentrations of radioactive material in a restricted area in excess of any applicable limit in the license.

20.2203(a)(3)(ii) Radiation or concentrations of radioactive material in an unrestricted area in excess of 10 times any applicable limit set forth in Part 20 or in the license.

20.2203(a)(4) Levels of radiation or releases of radioactive material in excess of the standards in 40 CFR Part 190, or of license conditions related to those standards.

30.50(a) Event that prevents immediate protective actions necessary to avoid exposures to 40.60(a) radiation or radioactive materials that could exceed regulatory limits or releases of 70.50(a) material that could exceed regulatory limits.

76.120(b) 30.50(b)(1) Unplanned contamination event that requires access to be restricted for > 24 40.60(b)(1) hours, involves > 5 times the lowest ALI, and has access restricted for a reason 70.50(b)(1) other than to allow isotopes with a half-life of < 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to decay.

76.120(c)(1) 30.50(b)(3) Event that requires unplanned medical treatment at a medical facility of an 40.60(b)(3) individual with spreadable radioactive contamination on the individual's clothing or 70.50(b)(3) body.

76.120(c)(3) 39.77(b) Theft or loss of radioactive material, radiation overexposures, excessive levels and concentrations of radiation for events involving well logging operations, and certain other accidents.

50.72(b)(3)(xii) Event requiring the transport of a radioactively contaminated person to an offsite 72.75(c)(3) medical facility for treatment.

The RLM event type includes two types of events. The first type is a radioactive release to air or water exceeding the 10 CFR Part 20 Appendix B annual limit on intake (ALI). The second type of RLM event involves contamination events such as a radioactive spill outside of work areas, removable contamination found on equipment, or material tracked around a laboratory such that additional radiological control measures had to be implemented. This event type does not include spills inside of laboratory hoods, radiopharmaceutical dose preparation areas, or hot cells where radioactive work routinely requires cleanup or changing of absorbent paper after the performance of a task. Should there be multiple release types (e.g., surface, air, water, or person) or areas of contamination associated with the release, this information is entered individually.

A-8 Leaking Sealed Source (LKS)

LKS events are determined and coded per the 10 CFR reporting requirements listed below.

Table A-6. LKS Reporting Requirements LKS Reporting Requirements Type of Source 31.5(c)(5) Generally licensed 34.27(d) Radiography 35.67(e) Medical 39.35(d)(1) Well logging (leaking) 39.77(a) Well logging (ruptured) 30.50(b)(2) All other sources

The NRC requires that most sealed sources be periodically leak tested to verify that the material is still sealed and that the source is still considered safe to use without contamination controls, including protective clothing or gloves. Sources are generally exempt from leak testing under the following conditions [see 10 CFR Part 31.5(c)(2), 34.27(c), 35.67(f), and 39.35(e)]:

• Sources containing only gaseous radioactive material (like H -3, Kr -85, etc.),

• Sources containing licensed material with a half-life of 30 days or less,

• Sources containing <= 100 Ci of other beta and/or gamma emitting material,

• Sources containing <= 10 Ci of alpha emitting material,

• Sources held in storage in the original shipping container prior to initial installation,

• Seeds of Ir-192 encased in nylon ribbon, or

• Sources in storage and not in use (must be leak tested prior to use or transfer).

A source is considered leaking if a leak test can detect greater than 0.005 Ci of removable radioactive material. The leaking source is then removed from service, disposed of or returned to the manufacturer for repair, and a report is sent to the NRC or Agreement State with the details of the leaking source.

For regulatory reporting purposes, a leaking source is generally considered a failed device under 10 CFR Part 30. Therefore, in most cases an LKS event is also coded as an EQP event. An exception is the Ni-63 foil source, which is coded as only an LKS event.

A-9 Equipment (EQP)

EQP events are determined and coded per the 10 CFR reporting requirements listed below.

Table A-7. EQP Reporting Requirements EQP Reporting Requirements Reporting Requirement Summary 21.21(d)(1)(i) A failure to comply or a defect affecting the construction or operation of a facility or an activity that is subject to licensing requirements.

21.21(d)(1)(ii) A failure to comply or a defect affecting a basic component that is supplied for a facility or an activity that is subject to licensing requirements.

30.50(a) Event that prevents immediate protective actions necessary to avoid exposures to 40.60(a) radiation or radioactive materials that could exceed regulatory limits or releases of 70.50(a) material that could exceed regulatory limits.

76.120(b) 30.50(b)(2) Equipment is disabled or fails to function as designed.

40.60(b)(2) 70.50(b)(2) 72.75(d)(1) 76.120(c)(2) 30.50(b)(4) Unplanned fire or explosion that damages any licensed material or any device, 40.60(b)(4) container, or equipment containing licensed material.

70.50(b)(4) 76.120(c)(4) 31.5(c)(5) Actual or indicated failure to shielding, the on-off mechanism or indicator, or upon the detection 0.005 µCi or more of removable radioactive material.

34.101(a)(1) Unintentional disconnection of the radiographic source assembly from the control cable.

34.101(a)(2) Inability to retract and secure the radiographic source assembly to its fully shielded position.

34.101(a)(3) Failure of any radiographic component (critical to the safe operation of the device) to properly perform its intended function.

35.3204 Eluate exceeding the permissible concentration of Mo-99, Sr-82, and Sr-85, as listed in 35.204(a), at the time of generator elution; more than 0.15 kBq Mo-99 per MBq Tc-99m, more than 0.02 kBq Sr -82 per MBq Rb-82 chloride, or more than 0.2 kBq Sr-85 per MBq Rb-82 chloride.

36.83(a)(1) An irradiator source stuck in an unshielded position.

36.83(a)(2) Fire or explosion in an irradiator radiation room.

36.83(a)(3) Damage to the irradiator source racks.

36.83(a)(4) Failure of the irradiator cable or drive mechanism used to move the source racks.

36.83(a)(5) Inoperability of the irradiator access control system.

36.83(a)(6) Detection of irradiator source by the product exit monitor.

36.83(a)(7) Detection of irradiator radioactive contamination attributable to licensed radioactive material.

36.83(a)(8) Structural damage to the irradiator pool liner or walls.

36.83(a)(9) Abnormal water loss or leakage from the irradiator source storage pool.

36.83(a)(10) Irradiator pool water conductivity exceeding 100 microsiemens per centimeter.

39.77(a) Ruptured well logging sealed source.

39.77(b) Theft or loss of radioactive material, radiation overexposures, excessive levels and concentrations of radiation for events involving well logging operations, and certain other accidents.

A-10 72.75(c)(1) Defect in any spent fuel, HLW, or reactor-related GTCC waste storage structure, system, or component that is important to safety.

72.75(c)(2) Significant reduction in the effectiveness of any spent fuel, HLW, or reactor-related GTCC waste storage confinement system during use.

72.242(d) Design or fabrication deficiency for any spent fuel storage cask delivered to a licensee which affects the ability of components important to safety to perform their safety function.

The EQP event type includes all types of radiological equipment problems, including generally licensed device problems covered in 10 CFR Part 31; radiography equipment problems covered in 10 CFR Part 34; irradiator problems covered in 10 CFR Part 36; well logging problems covered in 10 CFR Part 39, and other types of equipment covered in 10 CFR Part 30, 40, 70, and 76. EQP events are defined as the failure of, or a defect in, any piece of equipment that either contains licensed radioactive materials as an integral part, or whose function is to interact with such materials.

A-11 Transportation (TRS)

TRS events are determined and coded per the 10 CFR reporting requirements listed below.

Table A-8. TRS Reporting Requirements TRS Reporting Requirements Reporting Requirement Summary 20.1906(d)(1) Transported package exceeds removable surface contamination limits.

20.1906(d)(2) Transported package exceeds external radiation limits.

71.5 Transportation of licensed material.

71.95(a)(1) Significant reduction in the effectiveness of any NRC-approved Type B or Type AF packaging during use.

71.95(a)(2) Defects with safety significance in any NRC-approved Type B or fissile material packaging, after first use.

71.95(a)(3) Conditions of approval in the Certificate of Compliance were not observed in making a shipment.

71.95(b) Conditions in the Certificate of Compliance were not followed during a shipment.

A-12 Other (OTH)

The OTH event type includes the following types of events:

1. Doses to an embryo/fetus or nursing child reportable per 10 CFR Part 35.3047. Note that these events are not MED events (reportable per 10 CFR Part 35.3045).

2. Dose in an unrestricted area in excess of 2 mrem in an hour, but no individual received a dose in excess of limits (if a dose in excess of limits is received, the event is an EXP event).

3. 10 CFR 37 events that do not result in the actual theft, sabotage, or diversion of Category 1 or 2 quantities of radioactive material. Otherwise, the event is as an LAS event.

4. Reportable events that do not specifically fit into one of the previous event types.

For items 1-3 above, OTH events are determined and coded per the 10 CFR reporting requirements listed below. Due to the nature of item 4 above, other reporting requirements may also be used.

Table A-9. OTH Reporting Requirements OTH Reporting Requirements Reporting Requirement Summary 20.2203(a)(2)(iv) Dose in an unrestricted area in excess of 2 mrem in an hour, but no dose received in excess of limits.

35.3047(a) Dose to an embryo/fetus greater than 50 mSv (5 rem) DE from administration of byproduct material or radiation from byproduct material to a pregnant individual unless specifically approved, in advance, by the authorized user.

35.3047(b)(1) Dose to a nursing child greater than 50 mSv (5 rem) TEDE resulting from an administration of byproduct material to a breast-feeding individual.

35.3047(b)(2) Dose to a nursing child resulting in unintended permanent functional damage to an organ or physiological system, as determined by a physician, resulting from an administration of byproduct material to a breast-feeding individual.

37.57(a) Unauthorized entry resulted in actual or attempted theft, sabotage, or diversion of a category 1 or category 2 quantity of material.

37.57(b) Suspicious activity related to possible theft, sabotage, or diversion of a category 1 or category 2 quantity of material 37.81(c) Actual or attempted theft or diversion (or related suspicious activities) of a shipment of category 1 quantities of material.

37.81(d) Actual or attempted theft or diversion (or related suspicious activities) of a shipment of category 2 quantities of material.

39.77(b) Theft or loss of radioactive material, radiation overexposures, excessive levels and concentrations of radiation for events involving well logging operations, and certain other accidents.

A-13 A-14 Appendix B

Statistical Trending Methodology

B-1 B-2 Appendix B Statistical Trending Methodology

General The following is a general discussion of statistical trending techniques.

A common approach to the statistical analysis of trend is based on regression methods. In particular, it is often the case that a relationship exists between the values assumed by a pair of variables. For example, if x is time (in years), and y is the rate of events per year, then we could use regression methods to study whether there is a relationship between time and event rate.

Regardless of the application, it is standard practice to refer to x as the independent variable and y as the dependent variable. Another common term for the dependent variable is response variable, and the terms covariant and explanatory variable are sometimes used for the independent variable. Also, it is typical with regression modeling that the independent variable can be measured with little or no error, but the dependent variable involves a random error. Consequently, even if there is a deterministic functional relationship between the two variables, when data pairs (x1, y1), (x 2, y2),..., (xn, yn) are plotted, the points will not coincide exactly with the function, but instead will tend to be scattered. Such a plot is called a scatter diagram and shows the variation in the data. The plots in this report are bar charts containing the same information.

Fitting a Straight Line to Data Consider a linear function f (x)= +x (B-1 )

where and are unknown parameters. A common model is that y is the sum of a linear function of the form (1) and a random error term, e. Standard results on estimation and inference about the parameters of the model assume that e is a normally distributed random variable with mean 0 and constant (but unknown) variance, 2. These assumptions mean that:

• Each yi is an observed value of a random quantity that is normally distributed [with mean f(xi)], and

• All the observations yi are of variables with a common variance, 2.

The yi are also assumed to be observations of random quantities that are independent of each other.

Under these conditions, the usual approach to estimating the unknown parameters and is the method of least squares (LS). In this method, and are selected so that the sum of the squares of the vertical distances between the data points and the fitted line is as small as possible. The LS method leads to the estimates

n

ni i=1(xx)yi=d = -2 )

(x x)2 i i=1

y x,= -3 )

x and y are arithmetic averages. The estimated LS regression line is then y = x,= -4 )=

and=animae=of= is

B-3 n 2 i i1(yiy) s = = n 2. (B-5 )

Testing for Trend A trend exists whenever the true slope,, is not zero. We start the analysis with the idea that is zero, and then ask whether the data tell us otherwise. Two quantities computed from the data are used in this assessment. The first, the error sum of squares (SSE), appears in the numerator of s. It is defined as

n 2. (B-6 )

SSE 1= = i i(yi y)

This quantity is the number that is minimized in order to find the estimates of and. The differences being squared in SSE represent random variations that remain after the linear fitting process. The second quantity is the regression sum of squares (SSR), defined by the following equation

n 2 SSR 1= = i i y(y). (B-7 )

Note that SSR looks at deviations between the fitted line and the default notion that the data are constant and have no slope.

One can show by algebra that SSE =+SSRSST,= -8 )=

w he=htotal sum of the squares (SST), is defined as

n 2 SST = = i i y1 )(y. (B-9 )

SST measures the overall variation in the data. It is the numerator that would be used to estimate the variance in a sample from a normally-distributed random variable, where all the data in the sample have the same distribution (and thus no trend). This variance measures random variation in such a sample.

In the framework of the linear function (1), the regressions effectiveness is measured by the SSR term defined above. When it is small, the fitted curve will not differ very much from the horizontal line y = y.=

SSE will be approximately equal to SST, and, from the data, both SSE and SST will be estimates of mere random variation. In this case, the data does not provide evidence that is different from zero.

On the other hand, if the y values tend to vary linearly with respect to the independent variable, x, then some of the variation in the y values can be attributed to this dependence on x. Since SSR assesses the difference between the least squares predictions of the y values and the arithmetic mean, y, it is a measure of the variation which is explained by the linear relationship. When the slope of the fitted line is large, more of these differences will tend to be large, resulting in a large value of SSR.

In the equation, SST +=SSESSRe=ol=varion=isariioned=inwoar,==variai=

rarr=variaio=iarelaionsp eracionf=heol=varionhaxe=

=heeareionsh=is=called=heoeffn=ofermaion,=or=2, and is defined by: r

2 SSR. (B-10) r = SST

r2 is a fraction that varies from 0 to 1. It will be near 0 if most of the variation is due to randomness, and it will be near 1 if most of the variation is due to the linear relationship.

B-4 The closeness to 1 needed for the data to show that the slope is not zero depends on the number of data points. If the dependent data are independent, normally-distributed at each x, with constant variance, and no trend, then the quantity, F, defined by (n 2)r 2 F =1r2= -)=

cahown=F distribution with degrees of freedom 1 and n 2, where n is the number of data points. When the data satisfy the assumptions except that there is a significant trend, r 2 will be closer to 1 and the computed F statistic will be much larger. Specifically, if the computed F exceeds the upper fifth percentile of the F distribution with 1 and n 2 degrees of freedom, we infer that the data contain evidence that is not zero, at the 5% level of significance. In this case, we reject the null hypothesis that

= 0 and conclude that a statistically significant trend exists, with 95% confidence.

As an example, for an assumed set of data fit to the linear model, assume the r 2 = 0.9369 and that n is 13.

Then the calculated F is 163.3. The upper 95th percentile of the F(1,11) distribution is 4.84. Since 163.3 far exceeds the upper 95th F percentile, the linear model is statistically significant. In this example, the data show that it would be very unlikely for a trend not to exist. The linear model explains too much of the variation in the data for a trend not to exist.

Applying the Model to NMED Data The method described above was applied for each NMED event type, for the overall NMED data, and for additional subgroups of data when trends were found in the overall data. When the calculated F exceeded the 95th percentile, the trendline was shown on the graph and identified as being statistically significant.

In future reports, methods slightly different than that explained above could be employed because NMED data in many cases does not follow the assumptions listed above. In particular, three considerations apply.

• The data are counts, and thus are discrete rather than being normally distributed. This problem is most pronounced when the counts are relatively low or sparse. Also, normally-distributed data in general can be negative, but the counts are always greater than or equal to zero.

• Variations in counts tend to increase as the counts increase. If the events occur at random, with a constant occurrence rate in a particular year or quarter, then the variance of the count for that year or quarter is equal to the mean or average for that year or quarter. Thus, the assumption of a constant variance for the data in each year may not apply.

• Finally, more than one count can be associated with a single reported incident in a single event type.

This situation would occur, for example, if several pieces of equipment fail in an event or if several types of overexposure occur. In these cases, the data are not independent.

One way to address the first two concerns is to identify the number of licensees in various NMED event types and study the event occurrence rates rather than the counts. The rates are more likely to come from a continuum and might have a more constant variance.

Taking logarithms of the counts and then applying the LS method avoids the problem of possible negative trendlines. The resulting models can be converted back to the scale of the counts after the regression line is identified. In the scale of the counts, the resulting trend, if any, has a slight curvature.

Weighted regression is a method similar to the LS method described above, but it compensates explicitly for the effect of the different variances from year to year.

Another approach that deals with the first two concerns is to apply regression methods that have been designed specifically for counts. Poisson regression, for example, is based on the idea that the data in each

B-5 time period are counts observed from a Poisson distribution, with an occurrence rate that is described by the model. Given occurrence rates in each time period, and independent counts, the probability of seeing the observed data is easily computed by multiplying the occurrence probabilities for the individual time periods. The slope and intercept parameter estimates are selected so that the model maximizes the resulting likelihood function.

The third issue may have little effect on the results of a trend analysis, as long as there are many counts with relatively few occurring in clumps, no trends in the occurrence of clumps, and no large clumps of counts coming from a single event report. The best way to address the dependence issue is to identify and remove the duplicate counts prior to the trend analysis.

B-6 Appendix C

IAEA Radionuclide Categorization

C-1 C-2 Appendix C IAEA Radionuclide Categorization

Table C-1 lists the radionuclides that this report uses to determine the significance for events involving the loss, abandonment, or theft of radioactive sources. This list is derived from the IAEA Code of Conduct on the Safety and Security of Radioactive Sources (2004) and from IAEA Safety Guide RS -G -

1.9, Categorization of Radioactive Sources. Based on the amount of radioactivity involved, the radionuclides are grouped into five categories, with Category 1 being the most hazardous. These categories may be summarized as follows (derived from IAEA Safety Guide RS -G -1.9, Categorization of Radioactive Sources):

Category 1: Extremely dangerous. These sources could cause permanent injury within a few minutes if handled. Doses could be fatal to someone in close proximity to a n unshielded source for periods ranging from a few minutes to an hour.

Category 2: Very dangerous. These sources could cause permanent injury within minutes to hours if handled. Doses could be fatal to someone in close proximity to an unshielded source for periods ranging from hours to days.

Category 3: Dangerous. These sources could cause permanent injury within hours if handled. Doses could possibly (but unlikely) be fatal to someone in close proximity to an unshielded source for periods ranging from days to weeks.

Category 4: Unlikely to be dangerous. These sources would not cause permanent injury, although delayed health effects are possible. Doses could possibly (but unlikely) cause temporary injury to someone in close proximity to an unshielded source for a period of many weeks.

Category 5: Most unlikely to be dangerous. These sources would not cause permanent injury.

C-3 Table C-1. IAEA Code of Conduct Category 1 thr ough 5 Radionuclide Activity Thresholds Category 1 Category 2 Category 3 Category 4 Category 5 Radionuclide TBq Ci 1 TBq Ci 1 TBq Ci 1 TBq Ci 1 TBq Ci 1 Am-241 60 1,622 0.6 16.2 0.06 1.62 0.0006 0.0162 1.0e-08 2.7e-07

Am-241/Be 60 1,622 0.6 16.2 0.06 1.62 0.0006 0.0162 1.0e-08 2.7e-07

Cf-252 20 541 0.2 5.4 0.02 0.54 0.0002 0.0054 1.0e-08 2.7e-07

Cm-244 50 1,352 0.5 13.5 0.05 1.35 0.0005 0.0135 1.0e-08 2.7e-07

Co-60 30 811 0.3 8.1 0.03 0.81 0.0003 0.0081 1.0e-07 2.7e-06

Cs-137 100 2,703 1.0 27.0 0.10 2.70 0.001 0.0270 1.0e-08 2.7e-07

Gd-153 1,000 27,030 10.0 270.3 1.00 27.03 0.01 0.2703 1.0e-05 2.7e-04

Ir-192 80 2,162 0.8 21.6 0.08 2.16 0.0008 0.0216 1.0e-08 2.7e-07

Pm-147 40,000 1,081,200 400.0 10,812.0 40.00 1,081.20 0.4 10.8120 1.0e-05 2.7e-04

Pu-238 60 1,622 0.6 16.2 0.06 1.62 0.0006 0.0162 1.0e-08 2.7e-07

Pu-239/Be 60 1,622 0.6 16.2 0.06 1.62 0.0006 0.0162 1.0e-08 2.7e-07

Ra-226 40 1,081 0.4 10.8 0.04 1.08 0.0004 0.0108 1.0e-08 2.7e-07

Se-75 200 5,406 2.0 54.1 0.20 5.41 0.002 0.0541 1.0e-06 2.7e-05

Sr-90 (Y -90) 1,000 27,030 10.0 270.3 1.00 27.03 0.01 0.2703 1.0e-08 2.7e-07

Tm-170 20,000 540,600 200.0 5,406.0 20.00 540.60 0.2 5.4060 1.0e-06 2.7e-05

Yb-169 300 8,109 3.0 81.1 0.30 8.11 0.003 0.0811 1.0e-05 2.7e-04

Notes

1. The primary values are given in t erab ecquerel (TBq). Curie (Ci) values are provided for practical usefulness only and are rounded after conversion.

Appendix D

Revision of Data

D-1 D-2 Appendix D Revision of Data

NMED is a dynamic database with new reports and revisions to previous reports being added on a continuing basis. This activity can result in additions or subtractions to data that was published in previous issues of this report. Numerical changes in NMED numbers can result from several different types of technical changes to coded data. The most common types of changes to database records are:

• Record additions due to late reporting

• Record additions or subtractions due to changes in event type

• Changes between fiscal years due to event date changes on individual events

• Record additions or subtractions due to changes in event reportability

• Record additions or subtractions due to reclassifying a single combined event as multiple individual events (or vice versa)

• Record deletions due to duplicated records or NRC direction Figures D-1 through D -9 below display the changes in the data published in the previous annual report. A positive value indicates that records were added and a negative value indicates that records were removed.

The unusually high number of removed events shown in Figures D -1 and D -7 is primarily due to a data backfit in which events with fixed gauge source shutters suck closed were changed to non -reportable.

40

24

20

9 1 1 3 3

0

-4 -6 -6 -6 -5 -6 -5

-8 -8

-20 2014 2015 2016 2017 2018 2019 2020 2021 2022

Fiscal Year

Added Removed

Figure D-1. Changes to All NMED Event Data

D-3 10 8

6

5

2 2 1

0

-1

-5 2014 2015 2016 2017 2018 2019 2020 2021 2022

Fiscal Year

Added Removed

Figure D-2. Changes to LAS Data

10

5 3

0

-1

-5 2014 2015 2016 2017 2018 2019 2020 2021 2022

Fiscal Year

Added Removed

Figure D-3. Changes to MED Data

D-4 10

5 5

1

0

-1 -1

-5 2014 2015 2016 2017 2018 2019 2020 2021 2022

Fiscal Year

Added Removed

Figure D-4. Changes to EXP Data

10

5

2 1

0

-5 2014 2015 2016 2017 2018 2019 2020 2021 2022

Fiscal Year

Added Removed

Figure D-5. Changes to RLM Data

D-5 10

5

1

0

-5 2014 2015 2016 2017 2018 2019 2020 2021 2022

Fiscal Year

Added Removed

Figure D-6. Changes to LKS Data

10

5 4

1 1

0

-5 -4 -4 -4

-5 -6 -6 -5

-10 -8 -8

2014 2015 2016 2017 2018 2019 2020 2021 2022

Fiscal Year

Added Removed

Figure D-7. Changes to EQP Data

D-6 10

5

1 1

0

-5 2014 2015 2016 2017 2018 2019 2020 2021 2022

Fiscal Year

Added Removed

Figure D-8. Changes to TRS Data

10

5

1

0

-5 2014 2015 2016 2017 2018 2019 2020 2021 2022

Fiscal Year

Added Removed

Figure D-9. Changes to OTH Data

D-7