ML20049A038
| ML20049A038 | |
| Person / Time | |
|---|---|
| Site: | 07000398 |
| Issue date: | 01/30/2020 |
| From: | Mackey E US Dept of Commerce, National Institute of Standards & Technology (NIST) |
| To: | Office of Nuclear Material Safety and Safeguards |
| References | |
| Download: ML20049A038 (5) | |
Text
January 30, 2020 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 UNITED STATES DEPARTMENT OF COMMERCE National Institute of Standards and Technology Gaithersburg, Maryland 20888-License No. SNM-362 Docket# 70-398
Subject:
Licensee Reportable Event, "Concentration of radioactive material in excess of limit in the license"
Dear Sir or Madam,
This letter, and the attached 30-day report, provide the reporting requirements pursuant to 10 CFR 20.2203 (a) (3) (i), following the identification of the presence ofradioactive material (depleted uranium) in a quantity in excess of the SNM-362 license possession limits on January 2, 2020.
This occurrence identified at the National Institute of Standards and Technology (NIST)
Gaithersburg involved a quantity of depleted uranium of 55.72kg which is greater than the 55kg limit specified in the NIST SNM-362 radioactive materials license. As detailed further in the attached report, this occurrence did not involve any significant occupational dose or exposure of an individual in excess of the limits in 10 CFR 20.1301-Dose limits for individual members of the public.
A courtesy call was made by NIST upon discovery of the radioactive material in excess of the license limits to advise NRC Region I, and the SNM-362 Project Manager at NRC Headquarters, of the occurrence.
The attached report describes: (1) estimates of dose; (2) the levels of radiation and concentrations ofradioactive materials involved; (3) the cause of the elevated concentrations; and (4) corrective steps taken or planned to ensure against a recurrence, including the schedule for achieving conformance with applicable limits, ALARA constraints, generally applicable environmental standards, and associated license conditions.
Thank you for your attention to this letter and report. If you have further questions about this report, please contact the NIST Radiation Safety Officer, Mr. Manuel Mejias, at 301-975-5022 or manuel.mejias@nist.gov.
Si~~~ely, x;~~ 71 )n ttd~
Elizabeth A. Mackey
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Chief Safety Officer National Institute of Standards and Technology 100 Bureau Drive, Building 223 Room B304, MS 1730 Gaithersburg, MD 20899-1730 301-975-5149 elizabeth.mackey @nist.gov
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Attachment:
Thirty-Day Report cc: T. D. Naquin, Project Manager, NMSS/DFM/FFLB, NRC HQ C. Cahill, Chief, Commercial, Industrial, R&D, and Academic Branch, NRC Region I W. Copan, NIST Director H. Wixon, NIST Chief Counsel A.K. Thompson, NIST IRSC Chairman M. Mejias, NIST Radiation Safety Officer 2
Thirty-Day Report in Accordance 10 CFR 2203(a)(3)(i)
January 31, 2020 On January 2, 2020, NIST confirmed the presence of 55.72 kg of depleted uranium inside a container at one of the radioactive waste storage facilities located in the Gaithersburg, Maryland campus. The quantity exceeded the possession limit of 55 kg listed in the NIST SNM-362 radioactive materials license.
Upon confirmation of the presence of the material in excess of the limits, investigation efforts were started to understand why the material was not captured in the radioactive materials database maintained by NIST and courtesy notifications were made to the NRC Region I, Division of Nuclear Materials Safety and the NRC Office of Nuclear Material Safety arid Safeguards.
NIST promptly submitted a license amendment request to increase the possession limit to regain compliance and simultaneously started efforts for prompt disposition of the material via a radioactive waste broker. At the time of this report the material has already been removed from NIST by a radioactive waste broker and a license amendment request was submitted via the NRC's Document Control Desk.
No exposures to personnel occurred as a result of this event.
- 1. Estimates of dose Interviews with radiation safety personnel indicate that the drum containing the depleted uranium was located in a restricted facility dedicated to radioactive waste storage at NIST for many years. The storage facility has very strict access controls providing a high degree of assurance that no members of the public would have been exposed as a result of the elevated concentration of depleted uranium. The layout and shielding of the inside of the facility and operational controls, including frequent radiological surveys and dosimetry monitoring, also provide a high degree of assurance that radiation workers were not unnecessarily exposed.
- 2. The levels of radiation and concentrations of radioactive material involved The concentration of radioactive material in excess of the limits in the license was determined to be 55.72 kg of depleted uranium in the form of 10 plates of approximately
- 3. 74 kg each and one brick of approximately 18.3 kg. At the time of identification of the material, the NIST inventory was at 46.9 kg or 85.3% of the license limit.
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The theoretical dose rate associated with this quantity of depleted uranium is approximately 9 mrem per hour at 100 centimeters from a point source. The shielding provided in the storage facility and the storage configuration did not produce a distinguishable increase in the dose rates outside of the storage facility and the dose rate inside the storage room was not sufficient to be noticeable in personnel dosimetry results.
- 3. The cause of the elevated concentration The investigation of the origin of the source has revealed that the material was transferred from the Atomic Energy Commission to NIST, National Bureau of Standards at the time, around 1971 as demonstrated by the labeling found on the depleted uranium brick inside the storage drum. At the time, NBS maintained five separate radioactive materials licenses; one of them was specific to source material (SMB-405). In 1985 NBS and NRC agreed to merge all five radioactive materials licenses under the SNM-362 license. It appears that during the merger of the licenses the drum containing the 55.72 kg of depleted uranium was not recognized in the inventory resulting in a license possession limit lower than needed. This condition went unrecognized from 1985 to 2020 in part due to a limitation of the earlier radioactive materials databases which did not account for radioactive materials in the radioactive waste storage areas. While the current database does not have such limitation, it was assumed that all radioactive materials in the storage area were being counted in the inventory.
- 4. Corrective steps taken or planned to ensure against a recurrence, including the schedule for achieving conformance with applicable limits, ALARA constraints, generally applicable environmental standards, and associated license conditions
- a. Actions Taken (1) The drum contents were inspected to make sure that the totality of the material was accounted for and that no contamination or exposures occurred as a result of the elevated concentration.
(2) A license amendment requesting an increase to ensure compliance with the SNM-362 license limits was submitted.
(3) The drum containing the 55.7kg of depleted uranium was disposed as radioactive waste via a waste broker on January 16, 2020, effectively achieving compliance with the license limits.
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(4) An investigation of the extent of the condition in the storage area was conducted and it identified additional items ( other than depleted uranium) not being counted against the license limits, but none exceeding the limits. All items are now counted against the license limits.
- b. Further Corrective Actions Planned (1) Inventory spot checks will be performed periodically in the waste storage areas to ensure that the administrative controls are working as intended and preventing recurrence of having items stored in the radioactive waste areas not inventoried and checked against the license possession limits.
(2) Additional corrective actions will be developed and implemented should any issues be
. _ *-_ igentified duri~g ii:r\\'~nt~!)'_ spot ~l!_ecks,_i!}!en_ui,L ~n~ e~!emci! a~d_i!; or. ~C inspections.
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