The Nuclear Regulatory Commission carried an Event Report with a couple of updates concerning yesterday’s explosion and fire at Arkansas Nuclear One’s facility. Here’s a portion of the initial Event Report:
At approximately 0748 [CST] on 12/9/2013, an electrical fault occurred resulting in a fire and explosion on the ANO [Arkansas Nuclear One] Unit 2 Unit Auxiliary Transformer. This caused a unit trip and a loss of power to Startup 3 Transformer, which is one of the two offsite power feeds to ANO Unit 2.
The first new detail in the base report was this: “With Startup 3 and Unit Aux Transformer unavailable, power was lost to the Reactor Coolant Pumps and Circulating Water Pumps.”
The base report also specified how heat is being dissipated from the facility: “The unit is steaming to the atmosphere.”
The initial report also said that Unit 1’s Startup Transformer was declared inoperable, placing the reactor in a 72-hour Technical Specification shutdown, although that situation may have changed, since Unit 1 is listed at 100 per cent power in this morning’s Reactor Status Report.
The first update indicated that the Unusual Event was terminated just after noon yesterday. That update also included this: “…decay heat is being removed via emergency feedwater and downstream dump valves to atmosphere.”
The second update concerned a discharge to the plant’s cooling lake:
“Outside agencies (National Response Center, Arkansas Department of Emergency Management, Corps of Engineers, and U.S. Coast Guard) were contacted due to a minor unknown amount of oil that entered the plant discharge to Lake Dardanelle. The oil was from the faulted Unit 2 Unit Auxiliary Transformer. The majority of oil was contained within the containment around the transformer or the oily water separator it drains to. Local inspection revealed only a small amount of what was released actually passed the containment booms that are continuously in place on the discharge canal. The oil boom was verified to be in good condition. The oil was verified to be mineral oil.”