MISAWA AIR BASE, Japan — Japan’s Nuclear and Industrial Safety Agency has told operators of the nearby Rokkasho spent nuclear fuel storage facility to submit a report on how the company plans to address construction shortcomings at the facility.

Since 2001, 250 improper welds have been found in the Japan Nuclear Fuel Ltd. facility 25 miles north of Misawa.

Faulty welding was found in a cooling tank as well as ducts connecting the tank to the main facility, a Nuclear and Industrial Safety Agency report said.

The company inspected approximately 15 miles of welded pipes for other improper welds.

“We expressed deep regret that Japan Nuclear Fuel was not carrying out quality guarantees,” agency official Kenichi Nagayama said.

A document outlining ways to correct some of the oversights was given to the company June 24, he said.

“The agency instructed JNF to eliminate and take measures to never repeat them again,” Nagayama said.

While no exact deadline was set for completion of the report, Nagayama said it is “to be submitted as early as possible” to the agency.

The search for improper welds began when a tank of cooling water holding spent radioactive fuel rods began leaking in July 2001.

The stainless steel storage tank — measuring 89 feet long by 40 feet deep — developed a leak in its floor, allowing 1,056 gallons of radioactive cooling water to escape.

Japan Nuclear Fuel officials said that at no time did radioactive water seep outside the facility.

After the leak was discovered, 165 tons of radioactive fuel rods were removed and delivery of spent rods from other reactors was halted.

The problems were found during a Nuclear and Industrial Safety Agency inspection.

At the time, the company did not have an oversight system to monitor welding quality, the newspaper Asahi Shimbun reported. In addition, the company failed to report a number of repairs to central government officials.

Last November, Japan Nuclear Fuels officials said the leak was caused by faulty welding performed by Oye Kogyo Co., Ltd., a subcontractor for Hitachi Ltd.

Oye Kogyo, which specializes in the design and manufacture of equipment and machinery for nuclear power plants, filed for court protection from its creditors in late May.

Japan Nuclear Fuels spokesman Takashi Tomimori said the company was told to review three critical areas including improper welding in the storage tank, faulty construction where a stud dowel was found cut and failure to report on completed repairs.

“We are studying and coordinating in order to respond to the instructions,” Tomimori said.

The company was also toldto check for additional improperly welded areas and to investigate improved enforcement of the contractor oversight.

Japan Nuclear Fuel completed checks of its reprocessing plant in April but it is still checking the storage tank, Tomimori said.

Repairs to the tank must be made before it can be used to store fuel rods again.

However, Tomimori could not say when they will be completed.

Meanwhile, construction of a nuclear fuel reprocessing facility expected to begin operations in July 2005 is proceeding at the site.

But the stringent new measures could delay that scheduled start.

“It is hard to say until the results are received,” Nagayama said.

Hana Kusumoto contributed to this report.

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