The following event occurred on 9/7/17 but was not discovered until 1511 MDT on 10/30/17.
Appendix A to 10 CFR 70(b)(2).
While performing an extent of condition on a previous condition report in the UUSA [URENCO USA] corrective action program, UUSA discovered a product cylinder that had been introduced to the process inadvertently as a new or washed cylinder when it in fact was a heeled cylinder. The discrepancy caused the incorrect IROFS [Items Relied On For Safety] to be applied when connecting the cylinder to the process; IROFS16a for new/washed cylinders and IROFS16e/f for heeled cylinders.
The IROFS applicable (16e/f), administratively limits moderator (hydrogenous) mass in heeled cylinders containing enriched uranic material to ensure sub-criticality by limiting cylinder vapor pressure and heeled 30B cylinder weight. IROFS16e was completed SAT using the IROFS16a surveillance and the Product connect procedure. IROFS16f, an independent weight check and vapor pressure check, was not completed during the cylinder connect.
The IROFS performed (16a), administratively limits moderator mass (hydrocarbon oil and water) in new and cleaned 30B cylinders containing enriched uranic material to ensure sub-criticality by allowing no visible oil and by limiting cylinder vapor pressure.
Both of the aforementioned IROFS prevent criticality by limiting moderator mass, however the performance is different in heeled cylinders. IROFS16e/f are implemented by independently limiting cylinder vapor pressure and weight prior to introducing product into the cylinder.
Cylinder UREU103960 was connected to the process on September 7, 2017, filled with product material, heated, and liquid sampled. A criticality DID NOT occur. Existing sample results show normal for contaminants boron, technetium, and silica. Sample testing for purity showed UF6 at a temperature 24C acceptable per ASTM C996 standards of [greater than] 99.5 [percent].
10 CFR 70.50(c)(1)(iii):
(A) The IROFS not performed prevent criticality. No criticality occurred, no radiological hazard, nor chemical hazards were present.
(B) No exposure occurred.
(C) UUSA Shift Operations inadvertently treated the cylinder with the wrong classification. The pedigree of the cylinder was misinterpreted and the IROFS16a surveillance was performed instead of the correct IROFSI6e/f surveillance.
(D) IROFS remain available and reliable to perform their function. IROFS16 series are applicable during cylinder connects and are established by the performer of the cylinder connect evolution. The IROFS are not affected for future cylinder evolutions.
(iv) The cylinder is currently inside the Cylinder Receipt and Dispatch Building. No external conditions affect this event.
(v) UUSA immediately treated the cylinder as an anomalous condition in accordance with internal procedures and Operations Reporting Manual. The cylinder had been through the sampling process and the results are being reviewed by UUSA NCS/ISA Engineering staff.
(vi) No criticality event occurred. The cylinder is in a criticality safety anomalous condition. There are currently no other cylinders immediately adjacent and the area has been roped off.
(vii) No emergencies have been, nor will any be declared.
(viii) No state or other federal agencies will be notified.
(ix) No press releases are planned.
SAFETY SIGNIFICANCE OF EVENTS: No Event Occurred
SAFETY EQUIPMENT STATUS: The cylinder is in a criticality safety anomalous condition. Existing sample results from cylinder contents are being reviewed.
STATUS OF CORRECTIVE ACTIONS: Condition has been entered into facility's Corrective Action Program
The licensee will inform NRC Region 2 (Sykes).
- * * UPDATE AT 1629 EDT ON 11/02/2017 FROM RICARDO MEDINA TO JEFF HERRERA * * *
11/2/2017 1429 MST Update: Based on existing liquid sample results, conservatively assuming a moderator concentration of 0.5 percent, the filled cylinder's heel meets the acceptance criteria. This demonstrates a criticality event to be highly unlikely and therefore, the anomalous condition was exited at 1242 MST.
Notified the R2DO (Ehrhardt),
NMSS (via email) and Fuels Group (via email).