Press Release Back Number(2006)

Changes to report on engineering assessment and other matters regarding the age of Reactor No. 1 at the Hamaoka Nuclear Power Station

March 16, 2006
Chubu Electric Power Co., Inc.

In connection with the age of the reactor, Chubu Electric Power Co., Inc. has compiled and submitted on January 31, 2006 a report to the Minister of Economy, Trade and Industry on the engineering assessment and long-term maintenance plans for Reactor No. 1 at the Hamaoka Nuclear Power Station (which began operation March 17, 1976).
(Submission of this report was announced January 31, 2006.)


Later, in the process of inspecting this report, the Japanese government pointed out several matters concerning its content. In response, Chubu Electric Power has inspected the entire content of the report, in addition to matters such as a change in the representative equipment used for assessment and other revisions to the report content instructed by the government. Today, Chubu Electric Power submitted this revised report to the Minister of Economy, Trade and Industry.


Details of these revisions are described below. The overall results of the engineering assessment remain unchanged.


The report submitted today will also be inspected by the Japanese government.


1. Revisions to application of engineering assessment methods in light of the age of the reactor:

Although no change has been made to the engineering assessment methods, inadequacies were pointed out in certain stages of the practical implementation of these methods.

(1) Revisions at stage of selecting subjects of assessment

In the engineering assessment carried out in light of the age of the reactor, all equipment is categorized into groups based on factors such as their structures, usage environments, importance, and materials, and representative equipment to be subject to assessment is chosen from each group. Next, an engineering assessment is conducted for this representative equipment and the results of this assessment are applied to the other equipment in the group.

Since some equipment had been grouped based on incorrect materials and other information, the representative equipment subject to assessment has been revised. These revisions have been reflected in the revised report.


(2) Revisions at stage of choosing cases of aging

The equipment selected as subjects of assessment are separated by component, and anticipated cases of aging are chosen and subjected to the engineering assessment.

The government inspectors determined that, for some equipment, a more appropriate assessment could be conducted by choosing cases of aging based on revised methods of separating the equipment into its components. These revisions have been reflected in the revised report.


(3) Revisions at engineering assessment stage

Elements of the engineering assessment, such as assessment of the soundness of some equipment in light of wear, included calculation errors. Calculations for equipment involving such errors were redone and the revised results were reflected in the revised report.

Even under these revised results, the soundness of the equipment has been assured.



2. Other revisions to report content

In addition to revising inconsistencies in names of equipment, piping, etc., typos, and omissions in the content of the report, the content was also enhanced through means such as use of easier-to-understand expressions.


Note:

Pursuant to regulations governing installation, operation, and other matters related to nuclear reactors used for power generation, nuclear power plants are required to undergo an age-related engineering assessment before 30 years have passed since the start of operation, with the results of this assessment used to prepare a long-term maintenance plan for the next 10 years of reactor operation.