Event Notification Report for April 12, 2019

HIGH ENERGY LINE BREAK DOOR FOUND IN INCORRECT POSITION RESULTING IN LPCI AND CORE SPRAY BEING INOPERABLE

"At approximately 1815 CDT on April 12, 2019, High Energy Line Break (HELB) Door-410A in the Reactor Building was discovered in the closed position. HELB Door-410B was previously closed for maintenance. Either Door-410A or Door-410B must be open to support the current HELB analyses. With both doors closed, this is considered an unanalyzed condition resulting in the loss of a post-HELB safe shutdown path.

"With Door-410A and Door-410B closed, LPCI [Low Pressure Coolant Injection] and Core Spray injection valves in both divisions are no longer considered available.

"This condition is being reported under 10 CFR 50.72(b)(3)(ii) as an unanalyzed condition that significantly degrades plant safety and 10 CFR 50.72(b)(3)(v) as an event or condition that could have prevented the fulfillment of a safety function.

"The condition was resolved at approximately 1845 CDT on April 12, 2019 when Door-410A was blocked open. The health and safety of the public was not affected by this condition.

"The NRC Resident has been notified."

* * * RETRACTION FROM JESSE TYGUM TO HOWIE CROUCH AT 1330 EDT ON 5/24/19 * * *

"Event Notification (EN) #53997, made on 4/13/2019, is being retracted. An engineering evaluation completed subsequent to this event analyzed the discovered condition with both Door-410A and Door-410B being closed. The engineering evaluation determined that the environmental conditions present with both Door-410A and Door-410B closed would not have impacted the availability of both divisions of the LPCI (Low Pressure Coolant Injection) and Core Spray injection valves nor would it have resulted in the loss of a post-HELB safe shutdown path. Therefore, this condition did not meet the criteria for an 8-hour notification per 10 CFR 50.72(b)(3)(ii) as an unanalyzed condition that significantly degrades plant safety or per 10 CFR 50.72(b)(3)(v)(D) as an event or condition that could have prevented the fulfillment of a safety function.

"The NRC Resident Inspector has been notified."

The licensee also notified the Minnesota State Duty Officer. Notified R3DO (Cameron).

PART 21 REPORT - OVERHEATING AND FAILURE OF TRANSFORMERS

The following was received via e-mail:

"COMPONENT DESCRIPTION: AMETEK part number 80-315382-90, T801 main transformer.

"PROBLEM YOU COULD SEE: Overheating and failure of transformers installed in equipment with 0.7 power factor load requirements

"CAUSE: The inverters on AMETEK job number C72143 were required to support a 0.7 power factor load. To meet this requirement, CVT capacitors were added which led to overcurrent on the capacitor current windings and overheating. The overheating led to a breakdown in insulation between windings, causing a premature failure of the transformer set and inverter relative to its 40-year qualification life.

"EFFECT ON SYSTEM PERFORMANCE: The overheating accelerates the degradation of the insulation between windings and eventually leads to shorting. This will cause an inverter failure and require the load to be transferred to bypass.

"ACTION REQUIRED: This is the only instance AMETEK has experienced for this issue. Therefore, action is only required for the equipment on AMETEK job number C72143, located at TVA Sequoyah. New transformers have been provided as replacements that require fewer capacitors, contain additional venting to improve cooling, and include larger winding material to reduce current density. The main transformers (T801) installed in the serial numbers associated with this job (C72143-0111 through 0911) should be replaced to prevent any similar occurrences.

"AMETEK SOLIDSTATE CONTROLS CORRECTIVE ACTION: AMETEK has enhanced this particular transformer design to improve cooling and reduce capacitor current. Additionally, corrective action #175 has been issued in AMETEK's system.

"If you have any questions, please contact Mr. Mark Shreve of the Client Services group at 1- 800-222-9079 or 1-614-846-7500 ext. 6332. mark.shreve@ametek.com."

Sequoyah is the only site affected by this Part 21 Report.

PROCESS GAUGE STUCK SHUTTER

The following is a synopsis of an event received via email:

On April 11, 2019, a trained technician was in the process of performing the biannual inventory/shutter check when the individual reported that Kay Ray Model #7050, Serial #1399, 250 mCi, Cs-137 gauge located on 5B DTU (Deslime Thickener U/Flow) in the Deslime basement had a frozen shutter mechanism and cannot be closed, rendering the shutter non-operable.

The gauge won't be replaced until the first time the slurry pipeline goes down for repair. If the line goes down prior to that, the gauge will be replaced at that time.

Similar events in the past have never had an exposure to any individuals. In the event of an emergency, the gauge will be removed and placed on a piece of lead and brought to storage.

AGREEMENT STATE REPORT - FAILURE TO RETRACT RADIOGRAPHY CAMERA SOURCE

The following report was received from the Alabama Department of Public Health Radiation Control via facsimile:

"On 4/12/19, at 0645 CDT, a radiographer was shooting in the vault at ATL [American Testing Labs], when the source became un-retractable. [The radiographer] closed the vault door and called the RSO [Radiation Safety Officer].

"The RSO arrived 45 minutes later and checked the status of the crank and the positioning of the camera in the vault. The RSO then took apart the handle of the crank and manually pulled the source through the cable into a safe position within the camera.

"The crank was serviced and the RSO found some debris within the crank. The crank was cleaned and placed back into service. After several shots, the crank was operational.

"The RSO received 24 mR on his dosimeter and the radiographer received 0 mR."

Alabama Incident #19-09