十年后工作开始于12.2美元基本脉冲电平lion waste treatment plant at the U.S. Dept. of Energy's Hanford site in southeastern Washington—set to be the world's largest to treat "mixed" nuclear and chemical wastes—the 65-acre "vit plant" complex still faces uncertainty in cost and design, despite completion of 85% of its engineering and more than 60% of its construction.

The difficulty of designing the facilities needed to turn Hanford's 56 million gallons of liquid radioactive and chemical wastes into vitrified glass has DOE and its main contractor, Frederick, Md.-based Bechtel National, cautious as they stare down a 2013 design completion deadline for the project. Since its start in 2001, the project's price has tripled to the current $12.2 billion. Rising steel prices and technical issues in the final design could push it even higher. A Bechtel spokeswoman says if Congress ends up changing the way it appropriates money for the project, those changes could alter project delivery and affect the final price tag.

The vitrification complex will receive wastes now stored in deteriorating underground tanks that date back to Hanford's World War II origins as a nuclear bombmaking site. Its different facilities will remove water and solids, then mix the remaining heated waste with molten glass to be stored as logs in stainless-steel canisters. The plant "is a technically complex machine that requires constant vigilance and focus," says DOE spokeswoman Carrie Meyer. Construction is set for significant wrap-up in 2016. Operations are slated to start in 2019 and be at 70% capacity in 2022. Full operation was originally targeted for this year.

该过程需要建造四个主要的混凝土设施来预处理和单独的废物，并根据放射性水平验证废物，并提供实验室分析以及约20座用于操作和维护，公用事业和办公空间的支持建筑物。DOE Area项目经理Gary Olsen说：“ VIT工厂将在很大程度上具有独立性，像一个小城市一样运作。”

低级垃圾设施在11月达到了一个里程碑Bechtel项目经理John Platt说，标准说。

空气过滤系统包括合规性监控设备，HEPA过滤器，吸附者，热催化氧化剂，苛性洗涤器，排气风扇和130英尺高的排放堆栈。在运行时，吸附者将在通过热催化氧化剂引导空气之前捕获汞和酸气体，这将去除有机物和一氧化二氮。每个吸附者完全组装，长45英尺，宽12英尺，高14英尺，必须通过没有太大空间的舱口将其放到适当的位置。每个都包括近110英尺的18英寸DIA管道，需要组装7,000多个核质量焊接。Bechtel官员估计，该工厂建筑群将拥有约193英里的管道，并且至少需要65,000个工程焊缝。

The "nuclear-quality standard" required in the welded components led crews to use ultrasound equipment, post-fabrication, to test the strength and penetration of the orbital welds, a process they also will use with the associated piping, Platt says.

With such a large component nearly complete, Platt says crews learned lessons—especially surrounding the art of welding—they can now employ when fabricating the adsorber for the high-level waste facility. Meyer says minimizing heat input and restraining the plate, using double-V and double-bevel welds, pre-bending plates before welding and other measures can significantly reduce warping issues associated with welding.

下一个up for the seven-story low-level-waste facility comes installation of the thermal catalytic oxidizer in June 2012. At 6.5 million cu ft, the low-level facility is now 67% complete. The 8.6 million-cu-ft high-level facility is at 56% completion, with the 12-story, 13.9 million-cu-ft pretreatment center at 50% and the four-story, 2.6 million-cu-ft lab at 48%.

Officials monitoring the vit plant found technical issues regarding the way radioactive nuclear waste would be mixed at the plant, prompting questions of whether the waste would stay in the proper mix to prevent criticality, or critical mass. Determining if gases in tanks and piping would speed up corrosion was another technical issue.