OE information for restart of the Sendai nuclear power station

August 21, 2015
Kyushu Electric Power Company

Sendai Unit 1: Postponement of further load up(Electric conductivity rises around the condensate pump outlet)
The Sendai Unit 1 restarted generating electricity on Aug 14, 2015, and is currently
operating at 75% electric power. At 14:19, Aug 20, an alarm was activated to notify“Electric conductivity high/low” around the outlet of the condensate pump carrying thesecondary system coolant which does not include radioactive substance. This event iscategorized as Alarm level 1, “parameter fluctuation”.
Kyushu Epco investigated relevant components and water chemistry and made anassumption that a slight amount of seawater is included. The salt content is being
removed by the condensate demineralizer and there is no problem for the plant tocontinue operation.
In order to make extra sure the future operation will be even safer, Kyushu Epco has
decided to postpone further load up which was scheduled today and to conduct carefuland extensive inspections of the equipment. The electric output will be maintained as
75% during inspections.
There is no radioactive influence to the environment due to this event.

(Translated by JANSI)This is translation of articles in the press release by Kyushu Electric Power Company.
original text, please go to: http://www.kyuden.co.jp/press_150821-1.html

For theSchematic view of the Sendai Nuclear Power Plant
Moisture
separator heater[Legend]Primary system

Steam

Pressurizer

Secondary system (steam)Low pressure turbine

Secondary system (water)

Generator

Control rods

SeawaterHigh Pressure Turbine
Water

Electric
Conductivity Monitor(Indicator: high)Steam generator

WaterCondenser

To Water Discharge
Coolant (seawater)

Circulation Water Pump

Electric
Conductivity Monitor(Indicator: normal)

Condensate Pump

Electric
Conductivity Monitor(Indicator: high)Demineralizer
Deaerator

ReactorCoolant Pump

FuelHigh Pressure
Feedwater heater
Low Pressure
Feedwater heater

ReactorContainment Vessel
Main Feedwater Pump

High pressure Low pressure Low pressure Low pressure
turbine 1
turbine 2
turbine 3
turbineGenerator
Coolant(seawater)
inlet

AＢＣ

ＤＥ

Coolingtubes

Ｆ

Schematic of Condensers

Water
chambers

Coolant (seawater) outlet
Coolant (seawater) inlet

Structure of condenser

Terminology (Alarm level)“Alarm level 1”
Kyushu Epco previously identified a set of events which may occur duringrestart operations along with their individual countermeasures. The events are
categorized into five levels from Level 0 to Level 4 depending on the scale ofimpact on the plant operation.
Level 0: Emission of Alarm which can occur during normal activities(Mishandling of switches/levers in the control room)
Level 1: Emission of Alarm which requires enhanced monitoring ofcomponents which caused the event to happen(Parameter fluctuation)
Level 2: Events which requires measures to be taken but do not affect therestart process(Malfunction of components)
Level 3: Events which requires the grid to be disconnected (or load down)[Events related to the secondary system]
Level 4: Events which requires the reactor operation to stop
[Events related to the primary system]