EDF has provisionally appointed Xavier Girre, who joined the company last year as finance director of its French business, as the group finance chief.
The project has been plagued by delays, but publicly the firm has insisted a decision to move forward is imminent.
In October last year, EDF agreed a deal under which China General Nuclear Power Corporation (CGN) would pay a third of the cost of the £18bn project in exchange for a 33.5% stake.
But according to reports, EDF is struggling to find the cash for its remaining 66.5% stake and is seeking help from the French government, which owns 84.5% of EDF.
The company is also facing opposition from French union officials, who have suggested that investment in Hinkley Point C should be delayed until 2019.
The CFE-CGC Energy union said there were problems with a similar reactor design in France that needed to be solved.
The new Hinkley plant - to be built next to two existing facilities - is due to start generating in 2025, and is expected to provide 7% of the UK's electricity once it is operational.
But the project was originally due to open in 2017, and it has come under fire for both its cost and delays to the timetable for building.
The government has also been criticised for guaranteeing a price of £92.50 per megawatt hour of electricity - more than twice the current cost - for the electricity Hinkley produces.
Tony Roulstone, who is in charge of the masters programme in nuclear engineering at Cambridge University, said the departure of Piquemal was "a big blow".
He said EDF is already facing a number of other financing issues including a decision to buy a majority stake in Areva's nuclear reactor unit, adding: "They are committed to upgrading their existing power stations in France at a cost of €55bn over 15 years."
Mr Roulstone said: "At a commercial level there is a way for the Government to step aside but at a political level, this is part of the energy strategy."
Turkish and EU leaders have gathered in Brussels for an emergency summit on tackling Europe's worst refugee crisis since World War Two.
The EU aims to stem the flow of migrants and plans to declare the route north through the Balkans closed.
It will press Turkey to take back economic migrants and has pledged to give Ankara €3bn (£2.3bn; $3.3bn).
Last year, more than a million people entered the EU illegally by boat, mainly going from Turkey to Greece.
North Korea on Monday issued its latest belligerent threat, warning of an indiscriminate "pre-emptive nuclear strike of justice" on Washington and Seoul, this time in reaction to the start of huge U.S.-South Korean military drills.
Such threats have been a staple of young North Korean leader Kim Jong-un since he took power after his dictator father's death in December 2011. But they spike especially when Washington and Seoul stage what they call annual defensive springtime war games. Pyongyang says the drills, which started Monday and run through the end of April, are invasion rehearsals.
Raymond Tomlinson, the inventor of modern email and a technological leader, has died, his employer said Sunday.
Tomlinson died Saturday, the Raytheon Co. said; the details were not immediately available.
Email existed in a limited capacity before Tomlinson in that electronic messages could be shared amid multiple people within a limited framework. But until his invention in 1971 of the first network person-to-person email, there was no way to send something to a specific person at a specific address.
Tomlinson wrote and sent the first email on the ARPANET system, a computer network that was created for the U.S.
SEOUL South Korean and U.S. troops began large-scale military exercises on Monday in an annual test of their defenses against North Korea, which called the drills "nuclear war moves" and threatened to respond with an all-out offensive.
South Korea said the exercises would be the largest ever following North Korea's fourth nuclear test in January and a long-range rocket launch last month that triggered a U.N. Security Council resolution and tough new sanctions.
Isolated North Korea has rejected criticism of is nuclear and rocket programs, even from old ally China, and last week leader Kim Jong Un ordered his country to be ready to use nuclear weapons in the face of what he sees as growing threats from enemies.
WASHINGTON Republicans desperate to stop Donald Trump from capturing the party's presidential nomination are wrestling with whether to unite behind Ted Cruz, a polarizing figure popular with the conservative Tea Party movement.
Cruz, 45, a U.S. senator from Texas, won nominating contests in Kansas and Maine on Saturday, bolstering his argument that he is the leading alternative to Trump, 69, the blunt-spoken billionaire businessman.
Mainstream Republicans are unhappy with Trump's calls to build a wall on the border with Mexico, deport 11 million illegal immigrants and temporarily bar all Muslims from entering the United States.
By John Whitesides and Amanda Becker
WASHINGTON (Reuters) - Republican presidential hopeful Ted Cruz split victories in four nominating contests with front-runner Donald Trump on Saturday, bolstering Cruz's argument that he
Rush Limbaugh on Donald Trump, Marco Rubio and Ted Cruz. For the full interview, tune into the Fox News Channel at 2pm & 6pm EST.
“I think with the case of Trump, there’s a much bigger upside than downside,” said Limbaugh while appearing on “Fox News Sunday.”
Limbaugh also said he believes that the divide between the Republican establishment and conservatives is “longer, broader, wider than I have ever seen it.”