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Category:Report
MONTHYEARML24166A1982024-06-0707 June 2024
NIST - Independent Third-Party Second Nuclear Safety Culture Assessment, Revision 1
ML24064A1992024-03-0101 March 2024
Us Dept. of Commerce, National Institute of Standards & Technology (NIST) - Change to the Nbsr Requalification Plan in Response to an NRC Request for Additional Information (ADAMS Accession No. ML22223A146)
ML24064A0282024-02-29029 February 2024
Requalification Program for the Nbsr
ML24023A6212023-12-0606 December 2023
Us Dept. of Commerce, National Institute of Standards & Technology - Problem Identification and Resolution (Pi&R) Performance Area Assessment Report
ML24023A6192023-10-23023 October 2023
NIST Center for Neutron Research Reactor Operations and Engineering (NCNR-ROE) Assessment of NCNR-ROE Procedures Program
ML24023A6222023-09-0505 September 2023
Final Report - Safety Evaluation Committee (Sec)/Safety Assessment Committee (Sac)
ML24023A6232023-09-0101 September 2023
Independent Nuclear Safety Consultant Assessment of Training at the NIST Center for Neutron Research (NCNR) - Final
ML24023A6202023-07-11011 July 2023
Independent Nuclear Safety Consultant Assessment of the Root Cause Analysis Performed by NCNR Into the February 3, 2021 Event at the NIST Center for Neutron Research, Revision 1
ML23207A0412023-06-0202 June 2023
Us Dept. of Commerce, National Institute of Standards & Technology, Independent Third-Party Nuclear Safety Culture Assessment of the NIST Center for Neutron Research
ML23040A3402023-03-0909 March 2023
NIST Restart Authorization Technical Evaluation Report
ML22293B8082022-10-19019 October 2022
National Institute of Standards & Technology (NIST) - License Amendment Request
ML22350A0692022-08-19019 August 2022
Us Dept. of Commerce, National Institute of Standards & Technology (Nist), Response to Request for Additional Information on License Amendment Request - Gamma Spectrum Analysis Report
ML22227A1502022-08-15015 August 2022
Us Dept of Commerce, National Institute of Standards & Technology (Nist), Request NRC Permission to Restart the Reactor Upon Completion of Listed Corrective Actions and Recovery Efforts
ML22223A1462022-08-11011 August 2022
Docket Number 50-184 and the Nbsr Requalification Plan
ML21340A0072021-12-0303 December 2021
Analysis of Cooling Flow Through 29 Fuel Elements with Fuel Element 1175 Dislodged
ML21294A3722021-10-21021 October 2021
National Institute of Standards and Technology - Supplement to October 1, 2021 Report and Restart Request
ML21288A5532021-10-15015 October 2021
NIST Center for Neutron Research - Problem Identification and Resolution
ML21274A0252021-09-30030 September 2021
Corrective Action Plan Corrective Actions Required Prior to Reactor Startup
ML21274A0262021-09-30030 September 2021
Corrective Action Plan Corrective Actions Required Post-startup
ML21274A0232021-09-21021 September 2021
Latch Improvement Safety Analysis
ML21274A0222021-09-20020 September 2021
Root Cause Response, Revision 1
ML21274A0192021-09-13013 September 2021
Ncnr Twg Report Root Cause Investigation of February 2021 Fuel Failure, Revision 2
ML21274A0212021-08-12012 August 2021
Final Report Sec Subcommittee Report: Review of the Ncnr Event Response and Technical Working Root Cause Analysis and Corrective Action Plan
ML21274A0202021-06-0303 June 2021
Ncnr Twg Report Addendum to Root Cause Investigation of February 2021 Fuel Failure
ML21153A3972021-06-0202 June 2021
Requalification Program for the Nbsr
ML21340A0082021-05-17017 May 2021
Heat Transfer in a Disc Wedged Between Two Fuel Element Plates
ML18157A1382018-05-31031 May 2018
Technical Evaluation of the Preliminary Safety Evaluation Report Supporting the Conversion to Low-Enriched Uranium Fuel for the National Bureau of Standards Reactors
ML0907001322009-03-0303 March 2009
Us Dept. of Commerce, NIST, Response to Request for Additional Information on Operator Requalification Program
2024-06-07
[Table view]
Category:Miscellaneous
MONTHYEARML22227A1502022-08-15015 August 2022
Us Dept of Commerce, National Institute of Standards & Technology (Nist), Request NRC Permission to Restart the Reactor Upon Completion of Listed Corrective Actions and Recovery Efforts
ML21294A3722021-10-21021 October 2021
National Institute of Standards and Technology - Supplement to October 1, 2021 Report and Restart Request
ML0907001322009-03-0303 March 2009
Us Dept. of Commerce, NIST, Response to Request for Additional Information on Operator Requalification Program
2022-08-15
[Table view] |
Text
Nuclear Instrument Response As detailed in OI 1.1, reactor startup consists of power stops at 100 KW, 1 MW and 10 MW prior to ascension to full power. The stop at 10 MW requires the reactor operator to level at 10 MW for at least 5 minutes to look for indications of an abnormal fuel element position as described in step 4.8. Step 4.8 directs the reactor operator to shut down the reactor if fluctuations or oscillations of two or more nuclear channels indications are significant or abnormal. There are no criteria specified to determine whether any oscillations are seen as significant, it is left to the judgement of the reactor operator. Two previous instances of fuel elements being unlatched (1981 and 1993) showed power oscillations of 5-7% and on-the-job-training has been used to train some reactor operators to use this as an estimate for determining significance.
Figures 1 and 2 show traces that would have been seen by the reactor operator on a normal startup in December 2020, and that of February 3, which shows oscillations, but somewhat less than 5%. (note: the TWG root cause report stated oscillations of 1-2%. This was calculated using 10 second data taken from the recorders.) Also, for comparison is a normal operating trace of the recorder on the same resolution scale (Figure 3), and a plot with 5% oscillations and 7% oscillations, as would have been seen in previous events. Note that there is some statistical variation normally always seen, particularly at 10 MW and above. NIs at startup are at different levels due to shadowing of neutron beam shutters. Once the reactor reaches full power, these beam shutters are opened with the authorization of the reactor operator. After all shutters are opened, the NIs center closer to each other and are then adjusted based off a steady state thermal power calorimetric.
The operator on console (a Crew Chief with over 20 years experience) states that on February 3, that, during the 10 MW stop, there was a definitive determination by the operator and others in the control room at the time that the power trace was within normal limits. As a new regulating rod and controller had been installed earlier, the operator also considered that this might have the potential to affect oscillations.
Any changes in reactor plant conditions, such as installing a new regulating rod, will be included in the expanded change management framework which will include increased communications with operators of the effect of those changing conditions.
The corrective action of installing a noise gate on the Nuclear instrument channels (IE-SPI-1) will eliminate any subjective evaluation of whether oscillations are significant.
Figure 1. Normal startup on December 16, 2020. Figure 2. Startup on February 3, 2021.
Figure 3. Normal operating trend Figure 4. Simulated 5% variation Figure 5. Simulated 7% variation