ML21070A183

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Us Dept of Commerce, National Institute of Standards & Technology (NIST) - Addendum to Event Report
ML21070A183
Person / Time
Site: National Bureau of Standards Reactor
Issue date: 03/04/2021
From: Newton T
US Dept of Commerce, National Institute of Standards & Technology (NIST)
To:
Office of Nuclear Reactor Regulation
References
55094
Download: ML21070A183 (1)


Text

March 4, 2021 Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001

Subject:

Addendum to event report UNITED STATES DEPARTMENT OF COMMERCE National Institute of Standards and Technology Gaithersburg, Maryland 20899-Ref: NRC Event 55094, Docket 50-184, Facility License TR-5 Sirs and Madams:

On February 16, 2021, the NCNR (NIST Center for Neutron Research) submitted a 14-day report on the above event. We have continued to conduct detailed analysis of our sampling results from the event. As part of our due diligence in review of those results, we have discovered two items that we believe should be updated from the original 14-day report submission. The report stated that the initial sample collected at the boundary on Feb 3, 2021 at 1030 showed a small concentration of Cs-138 at 0.5% of 10 CFR Appendix B Table Values. Further analysis of the sample indicated a needed correction to the analysis resulting in a concentration that is 1.4% of the Appendix B values. In addition, the report states there was a sample on Feb 4 that showed very minute concentrations ofXe-133 and Xe-135 that was less than 0.1 % of the Appendix B limits.

Upon further review, it was determined that the sample result was not fully quantifiable and thus should not be used. However, a sample was taken at the reactor stack in the same time frame and using conservative assumptions demonstrates that at the 400 meter boundary location the concentration was less than 10% of the Appendix B effluent concentration limits.

Please feel free to contact me if you have any questions.

Thomas Newton Deputy Director and Chief of Reactor Operations and Engineering NIST Center for Neutron Research

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