Below are several articles and links about this situation:

ENE News posted a compilation of reports, 12-3-14:
CNN: Urgent – Emergency repairs reported at largest nuclear power plant in Europe — Prime Minister: I know that a nuclear accident has occurred (VIDEO)
http://enenews.com/cnn-urgent-emergency-repair-reported-largest-nuclear-power-plant-europe-prime-minister-accident-occurred-video
ENE News is an excellent source for nuclear news — Fukushima, Hanford, WIPP New Mexico, USS Ronald Reagan contamination, and more . Many comments posted below the articles have further excellent resources. 
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“Nuclear accident” in southeast Ukraine, PM Yatsenyuk says
From Deutsche Welle — DW, December 3, 2014
http://dw.de/p/1DydT

Ukraine’s government says a nuclear accident has occurred in the country’s southeast. The incident is said to pose no threat, however.

A statement from Ukraine Prime Minister Arseniy Yatsenyuk on Wednesday said a nuclear accident had taken place in the country’s southeast.

Ukraine’s energy minister said a short circuit led to a drop in production energy production, and insisted it posed no danger.

“The accident happened in the third block of the Zaporozhiya nuclear power plant in the power output section. This is in no way associated with the reactor, Volodymyr Demchyshyn said at a briefing.

“There is no threat … there are no problems with the reactors.” He added the accident affected the power output system “in no way.”

He said the plant would be running at full strength on December 5.

The International Atomic Energy Agency said on Wednesday that it was informed of the short circuit by Ukrainian authorities that that the nuclear power plant’s reactor remained safely shut down.

Under an international convention, a country should notify the IAEA about a nuclear accident that could affect other nations. The convention was adopted after the 1986 Chernobyl accident in what was then Soviet Ukraine.

Nuclear power accounts for 44 percent of Ukraine’s power production, according to the IAEA.

jr/ksb (Reuters, AFP, AP)

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Extensive article on radiation spikes recorded in Latvia corresponding with the time frame for when this accident occurred in SE Ukraine.

https://allegedlyapparent.wordpress.com/2014/12/03/accident-confirmed-at-ukraines-zaporizhye-nuclear-power-plant-link-to-latvia-radiation-spike-possible/
Accident confirmed at Ukraine’s Zaporizhye Nuclear Power Plant. (Link to Latvia Radiation Spike possible)

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Accident at Ukraine nuclear power plant: reports
By Barbara Kollmeyer
From MarketWatch, December 3, 2014
http://www.marketwatch.com/story/accident-at-ukraine-nuclear-power-plant-reports-2014-12-03

LONDON (MarketWatch) — Ukrainian Prime Minister Arseny Yatseniuk said Wednesday that an accident has occurred at a nuclear power plant in south-east Ukraine, according to media reports. “I know that an accident has occurred at the Zaporizhye NPP,” Yatseniuk said Wednesday, and he asked new energy minister Volodymyr Demchyshyn to be clear about when the problem will be fixed as it has worsened the power crisis currently in the country. Interfax Ukraine said the accident had occurred at a 1,000-megawatt reactor in bloc No. 3 at the power plant. Interfax said the bloc was due to come back onstream Dec. 5.

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DW article from June written with a definite Western perspective:
http://www.dw.de/ukraine-crisis-raises-risk-for-nuclear-reactors/a-17694776
Ukraine crisis raises risk for nuclear reactors

The article doesn’t explain why a Ukrainian citizen would want to damage a nuclear reactor so that would destroy his or her home. Ukrainian citizens live with Chernobyl and its ongoing damage. Why would they want to cause  more harm? 

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For an industry assessment of nuclear power in Ukraine:
http://www.world-nuclear.org/info/Country-Profiles/Countries-T-Z/Ukraine/
Nuclear Power in Ukraine