During the night of Wednesday 12 October the Swedish nuclear reactor Ringhals 3 was restarted following completion of the annual maintenance outage. One of the operations involved replacing a number of pipe connections inside the Ringhals 3 reactor. For this highly advanced task, Vattenfall called in 60 welding specialists from Japan's Mitsubishi Heavy Industries.
The Japanese specialists had previously carried out similar operations on 22 nuclear power plants in Japan, and prior to their work in Sweden they had also performed a full-scale test back at home.
"As far as timings are concerned, this is the most carefully prepared project I've ever been involved with, and the Japanese had planned each and every detail," says installation supervisor at Ringhals, Bengt Karlsson.
The Japanese group were on site at Ringhals for almost three months. Over that time they made their mark, both inside Ringhals and beyond.
One example of this was their daily exercise routine: every morning at 7 o'clock the Japanese group met to start the day with synchronised exercises.
"Morning exercise is mandatory in many Japanese companies. We learn the exercises in primary school, so all Japanese people know how to do them. At Mitsubishi we have communal exercises twice a day, first thing in the morning and then before the afternoon shift. It's a good way of warming up before the working day," says Jun Takahara, project manager at Mitsubishi.
In the staff canteen the chefs were shown how to cook Japanese food so they could give the long-haul guests their favourite meals, which were also enjoyed by Ringhals' employees.
The annual maintenance outage at Ringhals 3 started on 3 August. As well as replacing pipe connections, amongst others, detectors and cables in the reactor protection system were replaced and a number of routine tests were carried out, amongst others on the reactor containment. The capacity of Ringhals 3 is 1,063 MW.