ENS 58063
ENS Event | |
|---|---|
18:00 Nov 26, 2025 | |
| Title | Technical Specification Abnormal Occurrence |
| Event Description | The following information was provided by the licensee via phone and email:
On November 26, 2025, during a review of past flux trap loadings, it was identified that during the period from July 22, 2024, through August 4, 2024, the University of Missouri Research Reactor (MURR) exceeded the requirements of Technical Specification (TS) 3.8, 'Experiments.' Specifically, TS 3.8.b requires that 'The absolute value of the reactivity worth of all experiments in the center test hole shall be limited to 0.006 delta-k/k.' A review of the center test hole flux trap loading for those two weeks determined that the reactivity worth of experiments exceeded the 0.006 delta-k/k and has been re-estimated to have been approximately between 0.0061 and 0.0063 delta-k/k (from initial estimates of 0.0046 and 0.0048 delta-k/k). This underestimation of flux trap worth occurred due to inadequate programmatic controls applied to TS 4.8, 'Experiments,' specification b, which requires that 'The reactivity worth of an experiment shall be estimated or measured, as appropriate, before reactor operation with said experiment.' Specifically, multiple center test hole flux trap irradiation samples were run in the reactor without adequate prior reactivity worth estimation or measurement. As corrective actions to this issue, MURR is performing additional sample measurements and revising the process used for measuring and determining flux trap irradiation samples to prevent this issue from recurring. While the TS 3.8.b limitation is 0.006 delta-k/k, the analytical limit of the supporting safety analysis is 0.007 delta-k/k. This limitation is based upon the step insertion limits evaluated within the MURR Safety Analysis Report, Chapter 13. As a result, exceeding the 0.006 delta-k/k TS limitation by less than 0.001 delta-k/k does not result in an impact to reactor safety. This error does not impact any current operation or flux trap loading. This issue is being reported under TS 6.6.c(1) as it meets the TS 1.1.b and TS 1.1.f definitions for an abnormal occurrence. Specifically, TS 1.1.b defines an abnormal occurrence as an 'Operation in violation of limiting conditions for operations established in Section 3.0,' and TS 1.1.f defines abnormal occurrence as 'An observed inadequacy in the implementation of an administrative or procedural controls such that the inadequacy causes or could have caused the existence or development of an unsafe condition involving operation of the reactor.' The NRC Project Manager has been informed. |
| Where | |
|---|---|
| University of Missouri-Columbia Columbia, Missouri (NRC Region 0) | |
| License number: | R-103 |
| Organization: | Univ Of Missouri-Columbia (Misc) |
| Reporting | |
| Time - Person (Reporting Time:+-3.55 h-0.148 days <br />-0.0211 weeks <br />-0.00486 months <br />) | |
| Opened: | Deborah Farnsworh 14:27 Nov 26, 2025 |
| NRC Officer: | Sam Colvard |
| Last Updated: | Nov 26, 2025 |
| 58063 - NRC Website
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