EN Revision Imported Date : 3/8/2019
EN Revision Text: LOSS OR DEGRADATION OF SAFETY ITEMS
"[On February 11, 2019 at 1519 MST,] it was discovered that the calibration certificates for Measuring and Testing Equipment (M&TE) used to perform temperature trip IROFS [Items Relied On For Safety] surveillances, only had 1 set of calibration data. The instruments have an internal temperature sensor and an external input for temperature. Previously, the IROFS surveillances for IROFS 1, 2, 4, 5, 11, 43, C15, and C16 were performed using the external input.
"An external vendor, that performs the calibration for this M&TE, confirmed that the calibration had only been performed on the internal temperature sensor. This issue of how ATC-1 and ATC-2 (Jofra brand dry-block temperature calibrators) were calibrated is not currently an issue, as UUSA [URENCO USA] now only uses the Jofras as a heat source and uses a separately calibrated resistance temperature detector (RTD) and display for IROFS surveillances.
"Further investigation findings showed that a number of UF6 stations had not had their scheduled surveillance with the new method using a separately calibrated RTD. In total, 25 stations had their required annual IROFS surveillances performed with M&TE equipment which used an input that was not properly calibrated.
"The plant is in a safe condition."
The licensee will be contacting Region II.
* * * RETRACTION ON 3/7/2019 AT 1518 EST FROM BLAKE BIXENMAN TO ANDREW WAUGH * * *
"Event Notification (EN) 53869, made February 11, 2019, reported a condition in accordance with Appendix A to 10 CFR 70 (b)(2). The notification described degradation of items relied on for safety (IROFS) that could potentially result in failure to meet the performance requirements of 10 CFR 70.61.
"This notification was prompted by improperly calibrated Measuring and Testing Equipment (M&TE) which was used to perform surveillance activities for IROFS 1, 2, 4, 5, 11, 43, C15, and C16. At the time of the report, functionality of the IROFS' Active Engineered Controls within the acceptable parameters could not be verified. Therefore, URENCO USA (UUSA) conservatively assumed a degradation of IROFS resulting in failure to meet the performance requirements of 10 CFR 70.61.
"Since the time of the initial report, UUSA has re-performed surveillance activities using approved methods and obtained as found tolerances of the Active Engineered Controls for all of the affected stations. With this supporting data, UUSA has concluded that the affected IROFS were, at all times, operating below the maximum IROFS trip set point.
"The operating events using improperly calibrated M&TE can be categorized as events with low safety significance since they would not have resulted in breached/ruptured UF6 cylinders. Cylinder integrity would not have been compromised, as the temperature sensors were found to be available and reliable to perform their safety function. This correlates with a low consequence event.
"Based on engineering determinations and as found trip set points, the condition reported in EN 53869 did not result in failure to meet the performance requirements of 10 CFR 70.61. Therefore, the reported condition did not exceed the criteria which would necessitate an event be reported to the NRC. URENCO USA hereby retracts EN 53869."
The licensee has notified Region II.
Notified R2DO (Desai) and NMSS Events Notification (email).