Aggressive schedule keeps Kashiwazaki-Kariwa contractors on their toes

Aggressive schedule keeps Kashiwazaki-Kariwa contractors on their toes

Tokyo Electric Power Co. is setting a demanding pace as Unit 6 closes in on hydrotesting and initial fuel load schedule goals

Steven Kuehn

Power Generation Editor

Tokyo Electric Power Co. (TEPCO) and its group of primary contractors, Toshiba, Hitachi and GE, have set an ambitious pace in their quest to build the world`s first Advanced Boiling Water Reactors (ABWR) at TEPCO`s impressive Kashiwazaki-Kariwa nuclear power plant facility on the Sea of Japan. TEPCO and its consortia of contractors, which are sharing design, engineering and construction duties, have been steadily meeting and beating construction schedule goals without sacrificing worker safety or other quality parameters.

A recent trip to the site confirms that the efficiency and competence of the contractors, coupled with state-of-the-art construction methods, are likely to allow TEPCO to achieve commercial operation of Unit 6 on or before its scheduled December 1996 goal. Supporting this trend is the fact that the first hydrotesting procedure for Unit 6`s reactor pressure vessel was successfully completed ahead of schedule on May 18th. As of the end of May 1995, the completion rate for Unit 6 was approximately 86 percent and for Unit 7, 70 percent.

Schedule constantly scrutinized

As work progresses, TEPCO has continually scrutinized construction goals and systems, testing milestones in an effort to trim the original schedule. For example, TEPCO wanted to adjust the installation time of the Control Rod Drive Housings (CRDH). This task is tricky because it requires the precise alignment of each housing to the core plate to permit the successful coupling of the Fine Motion Control Rod Drive mechanisms to the control rods. To meet a two-week accelerated schedule demand, contractors deployed a temporary jacking platform, which allowed up to six CRDHs to be lifted into place and adjusted at one time. The contractor then applied multiple, automatic welding machines and alignment scopes and adjusted work schedules by increasing back-shift work to accommodate the new schedule. Ultimately, the installation of the 205 CRDHs, which began in November 1994 and finished in March 1995, did gain the two weeks requested by TEPCO.

Diverse construction technologies

From the outset, TEPCO guided its primary contractors to employ the latest in design and construction techniques. Unit 6 is being built using an all-weather method that employs a temporary steel frame, a tensioned-fabric roof and side curtains to shield construction activity from weather-related delays and problems.

Unit 7 is being built using the large-block method. This technique relies on a U.S.-supplied, high-capacity crawler crane with a 925-ton maximum lifting capacity. Last February, the crane lifted the reactor core containment vessel`s 500-ton top slab steel structure module and on May 19 lifted and placed the 832-ton reactor pressure vessel.

Other technologies are contributing a great deal to the construction effort. For example, an integrated computer-aided design system is being used to guide construction execution plans. It has the critical ability to plan heavy lifts so modules are placed correctly to match piping and rebar interfaces.

The field media board is another system that has enhanced the construction effort and contributed a great deal to overall worker safety and efficiency. Introduced at Unit 6, the field media board displays images, drawings and diagrams from computers in the construction office on a large screen at the job site. And, perhaps more importantly, it is used to quickly and directly convey complex instructions and safe construction and operations procedures to workers at the site.

Control room operational

As of early May, the control room was undergoing final functional verification testing and quality assurance procedures. Initial assembly and installation of the digital control system, which employs advanced man-machine control interface technology, began in September 1994. After a round of testing and regulatory approval, Unit 6 received power into its 6.9-kV power system January 31, 1995. The control system for Unit 6 shares the same room with Unit 7`s control room and uses the latest in optical multiplexing signal transmission network technology.

Meanwhile, site activity is extremely busy as TEPCO and its contractors near the completion date on Unit 6. Judging by past progress, it is likely that fuel loading and full power testing will begin on Unit 6 earlier than many might have expected. Look for upcoming announcements by TEPCO on further schedule adjustments.

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Tower crane for Unit 6 (left) has a 135-ton lifting capacity.

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Cranes (above) fill the sky at Kashiwazaki-Kariwa Units 6 and 7. Completion dates for the two units are set for late 1996 and mid-1997 respectively.

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Workers (above) inspect the turbine/generator coupling and bearings on Unit 6`s turbine.

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Technicians (above) complete verification testing of Unit 6`s control panel.

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Main steam isolation valves ready for duty.

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CRDHs (above) at the bottom of the reactor pressure vessel.

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