Hamaoka Nuclear Power Station Reactor No. 5 Undergoes Periodic Inspection
March 12, 2010
Chubu Electric Power Co.,Inc.
On March 15th, 2010, Chubu Electric will commence the 4th periodic inspection of Hamaoka Nuclear Power Station Reactor No. 5 (advanced boiling water reactor, rated output 1,267 MW). This reactor was automatically shut down during the Suruga Bay earthquake on August 11, 2009. The period of shutdown was subsequently extended to enable the replacement of low-pressure turbines, among other work.
The periodic inspection, including power adjustments, is scheduled to last about three months.
During this periodic inspection, the reactor, reactor cooling system, containment facilities and other equipment will be inspected, in addition to which the low-pressure turbines and 46 fuel assemblies will be replaced.
In addition, the inspections which are scheduled to be conducted while the plant is in operation as part of the Special Maintenance Plan formulated following the Suruga Bay earthquake will be carried out.
When the facilities are inspected, we will observe the radiation exposure standards specified by the relevant laws and regulations, and will attempt to restrict the radiation exposure of the workers involved as much as possible.
The inspections and evaluations to be carried out while the reactor was shut down and the repair of the turbines and other damaged equipment specified by the Special Maintenance Plan formulated following the Suruga Bay earthquake have been completed.
The seismograph readings at Reactor No. 5 were more intense than those at other reactors, and the results of these investigations will therefore be carefully compiled, and a further announcement will be made when this process is completed.
Major Inspections and Work Performed During Regular Inspection at Hamaoka Nuclear Power Station No. 5
(1) Major inspections
Inspection of reactor pressure vessel, structures inside reactor, and fuel
b. Reactor cooling system equipment
Inspection of pipes, heat exchangers, pumps and valves
c. Measurement and control system equipment
Inspection of control rod drive system, inspection and calibration of various measurement devices
d. Radiation control equipment
Inspection and calibration of various radiation control measurement devices
e. Reactor containment equipment
Seal testing of reactor building, containment equipment
f. Steam turbines
Inspection of open turbines, disassembly and inspection of main valves, inspection of auxiliary equipment
Inspection of scrapped equipment, fuel equipment, emergency backup generator equipment, electrical equipment, etc.
(2) Major work
a. Replacement of fuel rods
Of the total 872 fuel rods, 46 will be replaced.
b. Replacement of low-pressure turbines
Due to damage to vanes in the 12th stage of a low-pressure turbine occurring on June 15, 2006, the low-pressure turbines will be replaced by redesigned turbines.
*During operation of Reactor No. 5 at rated output, a vane in the 12th stage of a low-pressure turbine detached. The turbine was stopped, and the reactor was automatically shut down.
c. Modification of control circuits of control rod monitoring equipment
In response to "Responses to Coupling Defect between Control Rod Drive Mechanism and Control Rods in Tokyo Electric Power Company's Kashiwazaki-Kariwa Nuclear Power Station Unit No. 6" (NISA No. 3, NISA-134b-08-39/NISA-154b-08-5/NISA-166b-08-1, issued September 12, 2008) some of the control circuits that monitor the status of coupling between the control rod drive mechanism and the control rods will be modified.
(3) Inspections based on Nuclear and Industrial Safety Agency (NISA) documents, etc.
Inspection based on "Responses to Coupling Defect between Control Rod Drive Mechanism and Control Rods in Tokyo Electric Power Company's Kashiwazaki-Kariwa Nuclear Power Station Unit No. 6" (NISA No. 3, NISA-134b-08-39/NISA-154b-08-5/NISA-166b-08-1, issued September 12, 2008)
(Content of inspection)
In response to the NISA documents indicated above, the status of coupling between the control rod drive mechanism and the control rods will be confirmed during the periodic inspection. This assessment will be classified as an "Inspection of Control Rod Coupling."