V–3. GRADING OF HEPCO’ INVOLVEMENT

HEPCO determined what components the company should accept by itself and what products HEPCO would entrust the suppliers to accept on its behalf. HEPCO developed detailed acceptance criteria for each component of each system as per the table below. The items confirmed in commissioning tests were also accepted in accordance with this strategy. See Table V–1.

The roles and responsibilities to carry out confirmations and to manage the recorded data necessary for commissioning were shared in HEPCO as follows:

—Tests which could be carried out within one of the construction divisions were planned, implemented and managed in that division;

—System tests shared by two or more divisions were controlled by the System Commissioning Test Control Group;

—Plant tests (startup tests) were controlled by the Startup Test Control Group;

—Tests inspected by the authority or its technical support organizations (TSO) were controlled by the Quality Assurance Division with cooperation by the corresponding construction divisions and the System Commissioning Test Control Group.

V–4. PROCESS OF TURNOVERS

There were two different kinds of turnovers at Tomari; one was from the suppliers/contractors to the construction divisions of HEPCO and the other from the suppliers/contractors to the Operations Preparation Division of HEPCO.

The former turnover was applied to structural products such as civil works and entire buildings in the plant. To give an example, the reactor building was built by a construction company called Taisei Corporation and the primary coolant system components were installed in the reactor building by MHI. A room turnover of the pump room was necessary before the pumps could be installed. The responsible engineer for the civil and architectural contractor confirmed acceptance of the rooms at the turnover. Then a responsible engineer of the Mechanical Division took over the room from Taisei Corporation in the presence of the responsible engineer of the civil and architectural contractor. Following that, the responsible engineer of the Mechanical Division turned over the room to MHI for equipment installation. If damage to the equipment occurred after the turnover to the mechanical division, the equipment had to be repaired under the responsibility of the mechanical division.

The latter was a system turnover or plant turnover applied to systems and plant. These were transferred from suppliers to the Operation Preparation Division in the presence of the responsible engineers of the corresponding construction-related divisions, namely the Mechanical and the Electrical and I&C Divisions after completion of the commissioning tests. The commissioning tests were controlled by the System Commissioning Test Control Group. At the technical level, they were organized by the responsible engineers of the corresponding construction-related divisions, acting within a commissioning test implementation team. The responsibility of the system was transferred to the Operation Preparation Division after commissioning was completed. In cases where portions of a large system needed to be operated before the whole system was turned over, then that portion could be commissioned and provisionally turned over. For example, a complex system such as the CCWS required this kind of treatment.

A noteworthy practice by HEPCO was the fact that the commissioning and turnover of systems were done back to back. The responsibility of the operation and management of a system moved from the contractors/suppliers to the Operation Preparation Division immediately after its commissioning test had ended well.

Theoretically speaking, a damaged component caused by a failure under the watch of an operation crew had to be restored under the responsibility of the Operation Preparation Division. On the other hand, the flushing of the primary and secondary systems before the commissioning tests was still the responsibility of the construction contractor.

100

TABLE V–1. SAFETY CLASSIFICATION OF TOMARI NUCLEAR POWER PLANT

101

V–5. COMMISSIONING FOR SYSTEMS AND PLANT TURNOVER

There were two kinds of commissioning tests; one was the pre-operational test and the other the startup test which included the initial core loading and post-core hot functional tests. The split between the two types of commissioning tests was the time of the initial core loading. The installation of equipment had been completed before then and the number of operating systems reached the peak at that time. Therefore, the structure of the operations organization was very similar to that of a commercially operational plant. The staff engaged in construction activities was gradually moved to the administration office of the operating units during the 8 month period of the startup tests.

(1)Pre-operational tests:

—Component tests: E.g. H-Q characteristics of the RCP, pressure test of a CV, flow rate tests of safety valves, inspection of seismic supports of pipes, etc;

—System or subsystem functional tests except reactor system: E.g. level control test of volume control tank of CVCS, etc.

(2)Startup tests:

—Fuel loading and sub critical tests of reactor system;

—Initial criticality and reactor physics tests of the reactor system (at 0 power);

—System functional tests except the reactor system at power conditions;

—E.g. level control test of steam generators, control test of turbine bypass valves, etc.;

—Power and reactor physics tests of reactor system (at several power levels).

V–6. SECTORS IN CHARGE OF COMMISSIONING TESTS FOR SYSTEMS &

PLANT AND TRANSFER OF OWNERSHIP

Commissioning was a step necessary for the turnover of installed equipment, systems, facilities or the whole plant from the construction divisions to the operation division and had to be accomplished before their turnovers. Sectors in charge as per practice are shown below.

TABLE V–2. THE RESPONSIBILITY OF TEST SCOPE

102

At the moment of the turnover the ownership moved from the suppliers to HEPCO. The responsibility in maintaining the systems after their full turnovers or provisional turnovers was of HEPCO. Operations of turnedover systems were done by shift operators belonging to the Operation Preparation Division of HEPCO’s construction office. Even before the initial core loading, shift operators were engaged in the operation of turnedover systems such as the electric power buses and the component cooling water system (CCWS) needed for the commissioning tests of other systems.

The plant turnover from MHI to HEPCO occurred before the scheduled commissioning of the entire plant, since continuous operation for the duration established by contract was achieved at 100 % of the rated reactor power, which yielded at the time even greater electric power than rated by design. This was caused by a lower than design sea water temperature. There was actually a general celebration, since the plant had been turned over to HEPCO even before the completion date of the plant commissioning as foreseen in the official schedule.

103