August 25, 2015
Kyushu Electric Power Company

Sendai Nuclear Power Station Unit 1: Plant Status (Daily Report)[As of noon Aug 25: Results of the condenser tube investigation andthe load up schedule]
Operations[Electric power]

75% power is maintained as of 10.00am, Aug. 25

Results (10.00, Aug. 24 – 12:00, Aug. 25)[Main process] The primary system (reactor system)
 None The secondary system (turbine and generator system) The condenser is being examined (started on Aug 21)
 The station has confirmed that there are no other condenser tubes
which contain seawater than the tubes discovered yesterday (5 ofthem) A total of 69 tubes (approx. 0.5% of all waterboxes) including the 5affected tubes will be plugged as a precautionary measure.
Subsequently, the condenser will be recovered. Load up will be
implemented on Aug 27.
[Tests and inspections] Operator’s self-inspection (periodical equipment inspection items)
 None Regulatory inspection
 Reactor start-up inspections are ongoing (started on Aug. 3)

Plans (12:00, Aug. 25 – Aug. 26)[Main process] The primary system (reactor system)
 None The secondary system (turbine and generator system) Examination of the condenser (plugging of tubes, condenser recovery etc.)[Tests and inspections] Operator’s self-inspection (periodical equipment inspection items)
 Aug 26 Inspection of the water box of the affected condenser
 Regulatory inspection
 Reactor start-up inspections will continue

Translated by JANSI: for the original text, please go to: http://www.kyuden.co.jp/var/rev0/0047/9999/news150825.pdf

Aug. 25, 2015

Sendai Unit 1: Restart operation process
Constant operation at rated thermal power

Jul 7 Jul10▼▼
Fuelloading

Aug 10Jul 20 Jul 25 Aug 3▼▼▼▼
FunctionalRCS*tests
leak test*Reactor coolant system

Jul 13Jul 20▼▼
RVassembling

Jul 26 Aug 1▼▼
CV leakrate test

The above test periods include preparations
Jul 15 Jul 18
Aug 5▼ ▼Condenser Vacuum-up ▼Process

95%

100%

75%
50%
30%

Aug 13
Aug 11▼▼
Aug 14
Core physics▼Connecting to gridtest
Aug 13▼Turbine start-up
Aug 11▼Reactor start-up▼Criticality reachedThe secondary system cleanup

Aug 3
▼

Regulatory inspection on reactor start-up

Translated by JANSI: for the original text, please go to: http://www.kyuden.co.jp/var/rev0/0047/9999/news150825.pdf

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

Steam generator

Water

Condenser

Electric
Conductivity Monitor(Indicator: high)To Water Discharge
Coolant (seawater)

Circulation Water Pump

Electric
Conductivity Monitor(Indicator: normal)

Condensate Pump

Electric
Conductivity Monitor(Indicator: high)DemineralizerDeaerator

ReactorCoolant Pump

FuelHigh Pressure
Feedwater heater
Low Pressure
Feedwater heater

ReactorContainment Vessel
Main Feedwater Pump

High pressure Low pressure Low pressure Low pressure
turbineturbine 1
turbine 2
turbine 3

Generator
Coolant(seawater)
inlet

A

Coolingtubes
Waterboxes

Schematic of Condensers

Coolant (seawater) outlet
Coolant (seawater) inlet
See Appendix

Structure of condenser

Waterbox A in the condenser: location of affected tubes

Appendix：Affected and to be plugged(5 tubes)：Unaffected but to be plugged
as a precaution (64 tubes)

Reference 1

How to plug the condenser tubes (image)

Plug

Titanium

InsertingaTube

Rubbertitaniumplug into a tube (stillloose)

Plugging(Squash up the plug)*The other end of the tube will be plugged as well.

TitaniumReference 2

The environment around the affected tubes

 The location of the tubes which contained seawater is adjacent to the auxiliary drains for the No.6 high pressure feedwater heater
which emits a large volume of hot and high-speed water. Normally this type of drain is used only when the water chemistry is
adjusted during start-up operation of the plant.
 One of the possibilities would be that powerful drained water rushed to the condenser tubes/ the tube support plates, although it
had the baffle plate in between, and caused seawater to penetrate into the tubes.

Auxiliary drain outlet for
the No.6 high pressure
feedwater heater

A

Auxiliary drain outlet for
the No.6 high pressure
feedwater heater

Precautionaryplugging

Waterbox A
Baffle plate
Points from which
seawater came in

Baffle plate
A

Points from which
seawater came inCondenser A(View from the high pressure turbine)

Cross-section of AA