IAEA and the Year 2000 (Y2K) Issue - Rollover Reports: Japan

JAPAN
as of 01:54 UTC, 1 January, 2000

At 01:54 UTC, the following message was received by the Emergency Response Centre, IAEA, by fax from the Y2K National Co-ordinator, Ministry of Foreign Affairs of Japan, reporting on three minor incidents that occurred at nuclear power plants in Japan. The message was supplemented by a second fax at 02:56 UTC.

"The Anomaly of the Process Computer in Tohoku Electric Power Co. Ltd Onagawa nuclear power plants Units 1 & 2
"1 January 2000
Agency of Natural Resources and Energy, MITI

1. "Outline of the Incident.
"At 00:02 on 1 January 2000, in the No. 1 & 2 process computers of the Onagawa nuclear power plant (NPP) of the Tohoku Electric Power Co. Ltd., an alarm (Process Computer Detector Failure) was actuated and at 00:12 the alarm had been cleared automatically and normal operations resumed. During that time, data compiled in monitoring stations was not sent to the process computer, but after the resumption the system is functioning normally. Whether the incident was related to Y2K is currently under investigation. [N.B.: the subsequent fax of 02:56 UTC states that investigation has shown that the same alarm was actuated in similar incidents in November and December 1999, indicating that the cause of the incidents may not be Y2K related.] "The data itself was saved properly into a radiation management computer installed in the service building.

2. "Data not Transmitted
"The following data from the monitoring facilities:

1. Monitoring stations (Tohoku Electric Power Co., Ltd. has four stations, Miyagi Prefecture has six stations)

2. Sea water radiation monitors (Tohoku Electric Power Co., Ltd. possesses two)

3. Sea water temperature monitoring (Tohoku Electric Power Co., Ltd. possesses seven) 4. Meteorological facilities in power stations (Tohoku Electric Power Co., Ltd. possesses one)

3. "Transmission Interval
"Every ten minutes data is sent from the radiation management computer installed in the service building, to the process computers of Onagawa NPP unit 1 and 2. The data at 00:02 was not transmitted, but after the resumption the data is sent as normal.

4. "Influence on Safe and Stable Operation of NPPs
"Data relating to environmental monitoring was not sent properly to the main control room’s processes computer at the power station, but this will not affect the safe and stable operations of the NPPs. "The data which was not transmitted was saved as usual on the radiation management computer, installed in the service building."

"Report on Y2K Issues Related to Nuclear Power Plants
"1 January 2000

Nuclear Power Safety Administration Division

"As of 03:00 1 January 2000 when a confirmation was made of items outside of the parameters of the 13 important items necessary for safe and stable operation, it was confirmed that Shika Nuclear Power Plant Unit 1 of Hokoriku Electric Power Co. Ltd. in Ishikawa Prefecture (BWR with a rated output of 540 MWe) had experienced an anomaly in the display of its Safety Parameter Display System (SPDS) since midnight.

"Currently the investigation of the cause of this anomaly and the relation of the Y2K issue is underway.

"We should note that under ordinary circumstances the SPDS is not used to monitor the operating status of nuclear power plants. In fact, it is a contingency system which plays a role only in the event that an emergency situation occurs, at which time it transmits a report of the situation at the nuclear power plant to the headquarters of the electric power company operating the plant and to the Ministry of International Trade and Industry."

"Situation of the Ishikawa Prefecture Observation System
"1 January 2000

"The Ishikawa Prefecture Observation System, which was established in the area surrounding the Unit One Shika Nuclear Reactor of Hokuriku Electric Co. Ltd. in Ishikawa Prefecture, to measure radiation in the air and then inform local government if any nuclear accidents occur, had a technical disruption.

"The system is now able to collect and monitor data, but unable to transmit the data to the adequate local government service. It is not yet confirmed that this incident was caused by Y2K. In any case, this system consists of monitoring radiation level from outside of the Nuclear Reactor, and the disruption in question does not affect normal function of the Reactor."

At 11:15 UTC on 1 January 2000, the following message was received by the Emergency Response Centre, IAEA, by fax from the Japanese Authorities:

"Status of Nucler Power Plants (Regular hour report)
"1 January 2000

Press Release at 18:00
Ministry of International Trade and Industry
Agency of Natural Resources and Energy

"Electricity utility companies checked items important to safety and stable operation of the nuclear power plants and confirmed that no safety- nor stable-operation-related problem took place in all the plants up to 15:00. Among the following troubles, (1) has been tentatively evaluated to be categorized into INES (International Nuclear Event Scale) scale 0 (being non-safety-significant and having nothing to do with safety), and (2) through (4) are trivial ones not subject to INES evaluation (not to be press-released as troubles in usual cases). However the latter three have been exceptionally press-released from the viewpoint of Y2K problem. The four troubles are outlined below. The troubles have all been settled up to the present time.

"(1) At about 8.58 A.M. on January 1, an alarm of "Control Rod Position Indicating System Multiple Failure" was actuated at the unit-1 of the Tokyo Electric Power's Fukushima-Daini Nuclear Power Station (Boiling Water Reactor of 1100MW rated power) that was being operated at rated power, which resulted in loss of control rod position indication. Afterwards a failure in the error indicator of the control rod position indicating system panel was confirmed at 11:15 A.M. Checking the real time clock mounted on the control circuit board of the error indicator, etc. has revealed that time was erroneously set at February 6, 2036. The time was corrected to January 1, 2000, which brought the function of the control rod position indicating system back to normal at 14:12. The investigation of the cause is still on-going.

"(2) Check by the Kansai Electric Power at about 2:00 on January 1 revealed that the data from two monitoring posts installed in Maizuru City for Takahama NPP had not been transferred to Kyoto Prefecture, however the data transfer was recovered at about 6:30. The cause of the event is now under investigation.

"(3) The Hokuriku Electric Power checked Shika NPP unit 1 at 0:00 on January 1 and found that the display of SPDS (Safety Parameter Display System) had been in trouble since 0:00. The data display came back to normal at about 17:00. The cause is still under investigation.

"(4) At 0:02 on January 1, an alarm "Process Computer Detector Failure" was actuated at Onagawa NPP units 1 and 2 of the Tohoku Electric Power. But this was automatically returned to normal at 0:12 A.M. The same alarm was actuated again at 8:02 which was also cleared automatically at 8:12. Investigation of records revealed that the same kind of events took place in November and December, 1999. In addition, since the computer programs were remedied and tested against Y2K problem, it is not thought that the events were triggered by Y2K, however the cause will be investigated."

Note: This is being transmitted by the IAEA for information only and does not constitute a determination by the IAEA which States may or may not be physically affected by the event in question.

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