ML25113A262
| ML25113A262 | |
| Person / Time | |
|---|---|
| Issue date: | 08/28/2025 |
| From: | David Curtis NRC/RGN-III/DRSS |
| To: | Coffman D, Ryan Craffey, Randolph Ragland NRC/RGN-III |
| References | |
| Download: ML25113A262 (1) | |
Text
MEMORANDUM TO: Ryan Craffey, Senior Health Physicist, Team Leader Randolph Ragland, Senior Health Physicist Daisy Coffman, Health Physicist, (IDHS)
THRU:
Rhex Edwards, Chief Materials Inspection Branch Division of Radiological Safety and Security FROM:
David Curtis, Director Division of Radiological Safety and Security
SUBJECT:
SPECIAL INSPECTION CHARTER TO EVALUATE POTENTIAL RADIATION OVEREXPOSURE AT CURIUM PHARMA NOBLESVILLE, INDIANA You have been selected to conduct a special inspection in response to a report of a potential occupational overexposure at the Curium US, LLC facility in Noblesville, Indiana, of greater than 5 rem total effective dose equivalent to the whole body within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> due to loss of control of licensed material within the facility.
BACKGROUND AND BASIS Curium US, LLC (licensee) is authorized by NRC Materials License No. 13-35179-03 to produce strontium-82 (Sr-82) via cyclotron at a facility in Noblesville, Indiana, and is authorized by NRC Materials License No. 13-35179-02 to perform chemical purification of this material for distribution to authorized recipients. The company is also authorized by additional NRC Materials Licenses to produce and distribute a variety of other radiochemicals and radiopharmaceuticals at its main campus in Maryland Heights, Missouri.
On April 8, 2025, the licensee was conducting routine waste and remediation activities for a Sr-82 production hot cell in Noblesville. Prior to commencing the work, licensee personnel surveyed the area per a job-specific radiation work permit. The highest reading (930 mR/hr) recorded from the survey was from a partially unshielded area directly over a waste cask in a confined space below the hot cell. During the work, both personnel in the space noticed that their electronic dosimeters were alarming (100 mrem dose setpoint) and shortly thereafter exited the space. Their electronic dosimeter readings upon exiting the work area were 4.399 rem and 2.924 rem, several orders of magnitude above the doses anticipated for and typically received during this work activity. Subsequent surveys of the work area revealed exposure rates of 2 R/hr at the entrance of the confined space, 25 R/hr next to the work location, and >1000R (above saturation for the instrument used) on contact with a waste bucket opposite where personnel had been working. The individuals performing the work stated they did not handle the waste bucket while in the area. When the worker with an electronic dosimeter reading of 4.399 rem was manually frisked, they also exhibited a maximum of 25,000 dpm on the skin of their left hand. A urinalysis was performed on this worker, however no count rates April 28, 2025 Signed by Curtis, David on 04/28/25
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2 above background were detected, indicating no uptake. No other contamination of significance was noted, nor was any airborne radioactivity of significance detected.
This workers 2025 dose prior to performing the work was immediately reviewed and, when combined with the electronic dosimeter reading, their total dose was calculated to be 5.604 rem, which would exceed the annual limit set forth in 10 CFR 20.1201. The licensee issued a stop work order for production of work activities, sent the workers dosimetry badges for immediate processing, and initiated an investigation. The licensee reported this event to the NRC on April 9, 2025 (EN 57657).
On April 14, 2025, the licensee received the results of the immediate dosimeter badge processing from the worker with potential overexposure. Combined with their 2025 badge readings prior to performing the work, the individuals badges recorded total dose of 4.7 rem.
The licensee has since hired an independent health physics consultant to perform a dose reconstruction.
As required in NRC Inspection Manual Chapter (IMC) 1301, Response to Radioactive Material Incidents that do not Require Activation of the NRC Incident Response Plan, for incidents that result in a potential occupational overexposure, a reactive inspection was conducted on April 11, 2025. During the reactive inspection, the inspector determined that the contents of the waste bucket with excessive on-contact readings were unknown to the licensee. The inspector further determined that the licensee had adequate controls in place to secure the area with excessive readings and protect workers while it developed a plan to safely recover the material and resume normal operations. The inspector thereafter reviewed the plan once developed and concluded that it included adequate administrative and engineering controls and ALARA measures.
On April 17, 2025, the inspector returned to the site to observe the licensee implement its plan.
Although the waste bucket was found to be much heavier than expected, precluding full implementation of ALARA measures, the licensee was nevertheless able to successfully recover and regain control of the material, now known to contain Sr-82, its progeny and impurities. Workers involved in the recovery received 666 mrem and 268 mrem, respectively, well below the plans ALARA limit of 1 rem each.
NRC Directive Handbook (DH) 8.3, NRC Incident Investigation Program, I.D (2)(b) Criteria to Evaluate Level of Response to a Significant Materials Event, provides that additional investigation should be considered for a significant event that involves circumstances sufficiently complex, unique, or not well enough understood. Related criteria for special inspections in NRC Inspection Manual Chapter (IMC) 0309, Reactive Inspection Decision Basis for Power Reactors, provide that a special inspection should be considered where an event:
May have led to an exposure in excess of the applicable regulatory limits other than via the radiological release of byproduct, source, or special nuclear material to the unrestricted area; specifically, occupational exposure in excess of the regulatory limits in 10 CFR 20.1201; May have led to an unplanned occupational exposure in excess of 40 percent of the applicable regulatory limit (excluding shallow-dose equivalent to the skin or extremities from discrete radioactive particles); or
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3 Led to unplanned changes in restricted area dose rates in excess of 20 rem per hour in an area where personnel were present, or which is accessible to personnel.
Given that the licensee does not know the origin or identity of the material that caused the excessive readings, and given that the licensee had apparently no indication of the materials presence until after the exposures occurred, and that the unexpected dose to licensee personnel may have caused them to exceed an annual occupational limit, the Region has determined that a Special Inspection should be conducted.
Inspection Procedure 87103, Inspection of Material Licensees Involved in an Incident or Bankruptcy Filing, will be used to assist the inspection team in analyzing the sequence of events, the conditions that existed at the facility, and identification of contributing factors and root causes.
SCOPE The inspection team should seek to address the following items at a minimum:
1.
Develop a clear understanding of the circumstances leading to the potential overexposure, including, but not limited to, developing a chronology of events and actions taken by the licensee by:
a.
Identifying and reviewing pertinent records, documents, and procedural guidance related to Sr-82 production, cyclotron target handing, hot cell waste handling, personnel dosimetry use, radiation surveys, and control of NRC licensed materials.
b.
Performing observations of NRC licensed radiation activities, radioactive materials handling techniques, and use of protective equipment.
c.
Conducting interviews, as appropriate, with licensee staff, licensee contactors, and licensee management regarding the reported event.
2.
Assess the adequacy of the licensees initial response to the exposure, including, but not limited to, an evaluation of the licensees efforts to identify the cause of the potential overexposure and an assessment of the adequacy of the licensees immediate actions to prevent recurrence.
- 3. Evaluate the licensees dose assessment methods and results, including an evaluation of the licensees dose assessment for missing or suspected inaccurate readings and inclusion of occupational exposure from facilities other than the licensees facilities, as applicable.
4.
Evaluate the licensees material control and accountability measures, including physical inventories, materials receipt, and waste handing practices. Determine if the licensee is able to account for all cyclotron targets and other discrete sources of licensed material.
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4 5.
Evaluate the adequacy of the licensees program for any potential deficiencies that may have led to the potential overexposure, including an assessment of the following: licensees level of compliance with all applicable NRC requirements; operability and adequacy of radiation safety equipment that was available at the facilities; safety culture; and the effectiveness of radiation safety program oversight activities.
6.
Communicate the inspection teams findings internally and externally, including routine briefings with the licensee during the inspection, periodic briefings with NRC management, issuing public communications (such as press release and/or preliminary notifications), and any generic communications as required.
GUIDANCE Management Directive 8.3, NRC Incident Investigation Program, Management Directive 8.10, NRC Assessment Program for a Medical Event of an Incident Occurring at a Medical Facility and IMC 1301, Response to Radioactive Material Incidents That Do Not Require Activation of the NRC Incident Response Plan, provide guidance on the level of response. The inspection should be performed in accordance with Inspection Procedure 93812, Special Inspection.
Inspection Procedure 83501, Significant Uncontrolled Radiation Exposures and Inspection Procedure 87103, Inspection of Material Licensees Involved in an Incident or Bankruptcy Filing may also be of value.
The inspection should emphasize fact-finding in its review of the circumstances surrounding the handling of licensed materials, assessment of radiological conditions, and personnel exposure monitoring. Safety concerns identified that are not directly related to the event should be reported to the Region III office for appropriate action.
The planned dates of the onsite inspection are May 19-23, 2025. The team may travel on May 19, 2025, and should conduct an entrance with the licensee no later than May 20, 2025.
The team should conduct daily briefings with NRC management to discuss the teams progress and preliminary observations. In accordance with NRC Manual Chapter 0610, a report documenting the results of the inspection should be issued within 45 days of the completion of the inspection.
This Charter may be modified should the team develop significant new information that warrants review. Should you have any questions concerning this Charter, please contact David Curtis at 630-529-9800.
cc: Cortney Eckstein, Radiation Program Director Indiana Department of Homeland Security (IDHS)
CONTACT: David Curtis, DRSS (630) 829-9800
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5 Memorandum to R. Craffey, et al. from D. Curtis dated April 28, 2025
SUBJECT:
SPECIAL INSPECTION CHARTER TO EVALUATE POTENTIAL RADIATION OVEREXPOSURE AT CURIUM PHARMA NOBLESVILLE, INDIANA Distribution:
Jack Giessner Mohammed Shuaibi David Curtis Jared Heck Rhex Edwards Darren Piccirillo Robert Orlikowski Ryan Craffey Jacob Zimmerman Monica Ford Randolph Ragland Tamara Bloomer Dafna Silberfeld Carolyn Wolf Alejandro Alen Arias Tim Steadham ADAMS Accession Number: ML25113A262 Publicly Available Non-Publicly Available Sensitive Non-Sensitive OFFICE RIII/DRSS RIII/DRSS NAME REdwards:mh DCurtis DATE 04/24/2025 04/28/2025 OFFICIAL RECORD COPY