Results of Survey of Omission of Construction-related Procedures required by the High Pressure Gas Safety Law at Hamaoka Nuclear Power Station and Measures to Prevent Reoccurrence

Having determined that construction-related permission application and notification procedures required by the High Pressure Gas Safety Law had been omitted at its thermal power stations in Mie Prefecture, Chubu Electric conducted a survey to determine whether similar oversights may have occurred at the Hamaoka Nuclear Power Station. This survey showed that procedures in relation to application for permission for and notification of the replacement of three valves in auxiliary facilities for the generators in Hamaoka Nuclear Power Station Reactors No. 3 and 4, required by the High Pressure Gas Safety Law, had been omitted.

In relation to this matter, on December 24, 2010, Chubu Electric Power received instructions from Shizuoka Prefecture to report regarding the status of observation of the stipulations of the High Pressure Gas Safety Law in relation to its high-pressure gas facilities located in Shizuoka Prefecture, and is presently proceeding with the related survey.

The results of the survey of Hamaoka Nuclear Power Station and the details of measures to prevent a reoccurrence of this problem will be reported herein. The details presented will also be reported to the Shizuoka Prefecture administration today.

1. Status of observation of High Pressure Gas Safety Law at Hamaoka Nuclear Power Station

(1) Status of observation of High-pressure Gas Safety Law when facilities were installed

It has been determined that there were no omissions of permission application or notification procedures in relation to facilities to which the High Pressure Gas Safety Law applies at the time of installation.

(2) Status of observation of High Pressure Gas Safety Law during modification of facilities

It has been determined that, of the facilities to which the High Pressure Gas Safety Law applies, the required permission application and notification procedures required by the High Pressure Gas Safety Law were omitted in relation to the replacement of three valves in auxiliary facilities for the generators in Hamaoka Nuclear Power Station Reactors No. 3 and 4, for a total of seven cases.

(3) Overview of facilities in relation to which permission application and notification procedures were omitted / Purpose of facilities

Hydrogen and nitrogen storage facilities for the generators in Hamaoka Nuclear Power Station Reactors No. 3 and 4

Storage capacity	Compressed hydrogen gas	1,128 m3
	Compressed nitrogen gas	846 m3
Purpose	Hydrogen gas is used for cooling of generators. Nitrogen gas is used for safety purposes (prevention of fires in generators).

2. Results of survey of causes (determination of problem points)

It is conjectured that omissions of permission application and notification procedures required by the High Pressure Gas Safety Law occurred for the following reasons.

• In-house rules have been formulated in relation to determining the necessity for permission application and notification procedures required by the relevant laws at the construction planning stage, but small-scale work such as the replacement of parts with parts of the same specifications (replacement of valves, etc.) and regularly scheduled work such as the replacement of parts with spares was regarded as falling outside the scope of these rules.
•  It was mistakenly judged that the replacement of parts with parts of the same specifications did not represent facility modification work. In addition, management procedures were erroneous, with "When modified" being indicated in the "When to submit" column on the management table for documentation to be submitted to the relevant agencies.

3. Measures to prevent reoccurrence at Hamaoka Nuclear Power Station

(1) Corrective measures (measures to be implemented as soon as possible)

Chubu Electric Power will implement the following corrective measures as soon as possible in relation to the problem points determined by the survey of causes.

Improvement of in-house rules concerning construction procedures based on the High Pressure Gas Safety Law

• The rules concerning judgment of the necessity for permission application and notification procedures at the construction planning stage will be revised to incorporate checks in relation to regularly scheduled work.
  In addition, the fact that permission application and notification procedures must be implemented when replacing parts with parts of the same specifications will be clearly stated on the management table for documentation to be submitted to the relevant agencies.
• Management staff possessing the requisite knowledge, and working in areas unrelated to construction work processes, will review construction plans and other documents from the perspective of observance of the relevant laws, and will do their utmost to prevent any similar occurrences.

(2) Measures to prevent reoccurrence

Chubu Electric Power is at present proceeding with surveys to determine whether any similar instances have occurred within the company, and will put in place measures to prevent any reoccurrence based on the results of those surveys.

In addition to such measures, the following measures to prevent a reoccurrence of this situation will be put in place at Hamaoka Nuclear Power Station.

 i)  Review and development of in-house rules related to the relevant laws

We will review and enhance company rules to enable us to correctly implement procedures required by the stipulations of construction-related laws.

ii) Enhancement of review system

We will build a system with associated rights and responsibilities as framework to enable checks with regard to duties related to construction procedures, etc. required by the relevant laws.

iii)    Checks of status of implementation of measures to prevent reoccurrence

We will check on the status of implementation of measures to prevent reoccurrence by means of internal monitoring by an independent company body.
In addition, we have decided to have the status of management required by the stipulations of the High Pressure Gas Safety Law reviewed by an external specialist organization.

Reference

• Results of Survey of Omission of Construction-related Procedures Required by the High Pressure Gas Safety Law at Hamaoka Nuclear Power Station and Mea[PDF:212 KB]