KEPCO seems to have much thicker skin than TEPCO, if that's even possible.
KEPCO says the alarm at one of the thermocouples inside the Reactor 4 Pressure Vessel has been triggered 137 times since the reactor started the full operation on July 25, but it's not a problem, things will sort themselves out soon.
From Mainichi Shinbun Fukui local version (8/3/2012):
KEPCO announced on August 2 that an alarm was sounded 137 times as of 3PM that day which indicated the rise in local temperature of the primary coolant [water] inside the Reactor Pressure Vessel in Reactor 4 (1.18 million kilowatts) at Ooi Nuclear Power Plant. The alarm was first sounded in the early morning on July 25, when the reactor started the full operation. The temperature of the coolant around one of the nuclear fuel assemblies (193 assemblies total) rose to the level that would trigger an alarm.
According to KEPCO, the particular fuel assembly had been used once before and had relatively high fuel burnup. The company says that a change in the amount of flowing water temporarily raised the temperature of the coolant. KEPCO doesn't think there is any problem with the fuel assembly arrangement based on the fuel burnup, and says the temperature will stabilize by the middle of this month.
On July 30, the power output was decreased by 1.8% as both Reactors 3 and 4 reduced the amount of seawater intake because of jellyfish.
(So jellyfish are still protesting...)
KEPCO's press release on 8/2/2012 includes their explanation (in the attachment No.3) of why the alarm is being triggered and why it is no problem, in a very technical term (again, they outdo TEPCO).
From what I could figure, the thermocouple at this particular fuel assembly has been registering temperature higher than the standard (between 305 and 336 degrees Celsius), but it is because this assembly has high fuel burnup having been used once already, and as the time goes the relative output of the fuel assembly will drop, and the temperature will drop. The current cycle is the cycle No.15, and KEPCO uses more fuel assemblies that have been used once than in the previous two cycles, so the higher temperature is to be expected. As long as the temperature is below the saturation temperature (345.3 degrees Celsius), there is no problem with cooling.
(I put the English labels. KEPCO's press releases in English are almost all about financial results for the investors. They do have an English press release on the restart of Ooi Nuke Plant, dated June 16, 2012, if you're interested, here.)
Ooi Nuclear Power Plant's two reactors are both pressurized-water reactors from Mitsubishi Heavy Industries.
The temperatures of the coolant inside the PWR, according to wiki, is 275 degrees Celsius as the water enters the RPV at the bottom, and 315 degrees Celsius as it flows upward to the reactor core.