3 April, 2015
Pre-Service Inspection Starts at Sendai-1 before Restart
On March 30, Nuclear Regulation Authority (NRA) began its pre-service inspection of the Sendai-1 Nuclear Power Plant (PWR, 890MWe), in Kagoshima Prefecture, owned and operated by the Kyushu Electric Power Co.
A pre-service inspection of equipment and facilities is necessary prior to restarting the reactor. This is the first such inspection to be fully implemented under the new regulatory standards issued after the accident at the Fukushima Daiichi Nuclear Power Station in March 2011. They require a range of careful inspections of new equipment intended as countermeasures to severe accidents.
Units 1 and 2 of the Sendai NPS were the first NPPs recognized by the NRA last year as conforming to the new regulatory standards. At Unit 1, many new items of equipment have been installed as safety measures.
For the units to be restarted, pre-service inspections must be conducted to confirm that the installation of equipment was proper and that performance will be as intended. On the first day of the inspection, March 30, five NRA inspectors interviewed staff members at Unit 1 about the methods used in their work.
Pre-service inspections are being carried out both of newly-installed equipment at NPPs, and of modifications to and renovations of existing equipment. At Unit 1, various pieces of equipment were newly installed to meet the requirements of the new regulatory standards,
There are about 1,200 inspection items, primarily related to severe accidents. They include the following:
- Additional pumps to inject water into reactors and containment vessels
- Systems where generated hydrogen and oxygen are combined into water to prevent hydrogen explosions
- Piping to feed cooling water to spent fuel pools
Inspections will be made to confirm that the devices and systems have the intended design capabilities. Without the inspections, the NPP cannot be restarted. The inspections, in addition to checking dimensions and the state of installation, will carry out test operations, such as seeing if a pump can pump water at the necessary pressure.
At the final stage of the inspection, the reactor will be started up, and output will be increased, with a comprehensive performance check of the entire system to be made, including new equipment. If no problems are found, a certificate will be issued.
Kyushu Electric Power has released the following schedule for the inspection process:
- In early June, during the pre-service inspection, nuclear fuel assemblies will be loaded into the reactor of Unit 1.
- In early July, control rods will be removed to start up the reactor.
- After a week or so, Unit 1 will begin generating electricity.
- At the end of August, commercial operations will resume.
The inspection may be prolonged, however, because it has to be implemented thoroughly and with certainty.