What Is “Cold Shutdown?”

Several news articles late this week have reported that Japan’s Fukushima Daiichi nuclear plant may be in “cold shutdown” by mid-December. Although the reports are mostly accurate, there is a difference between the traditional “cold shutdown” of a nuclear plant and what is happening at Fukushima.

First, what is cold shutdown? The U.S. Nuclear Regulatory Commission defines it as:

The term used to define a reactor coolant system at atmospheric pressure and at a temperature below 200 degrees Fahrenheit following a reactor cooldown.

In non-nuclear speak, it basically means the conditions within the nuclear reactor are such that it would be impossible for a chain reaction to occur. This term usually comes into play whenever a reactor is shut down periodically for refueling or for the final time prior to the long-term before it is decommissioned. When a reactor is in cold shutdown, the reactor pressure vessel (RPV) can be safely opened with great care and additional water is added to the cavity above the vessel for shielding to permit safe handling of the fuel for refueling (replacing depleted fuel elements) or defueling (removing the entire core).

$C:\WINDOWS\Desktop\Text\03 with colored photos.wpd$ In Fukushima Daiichi’s case, achieving the strict definition of “cold shutdown” is not possible because the RPVs have been breached. This means that the RPVs will not hold water (currently the cooling water is flowing through them) and some of the melted fuel may not be in the vessel, but rather on the floor below, which is still within the primary containment. To clean up the plant, Tokyo Electric Power Company (TEPCO), the plant’s owner and operator, will work with the Japanese government and other parties to develop a long-term plan that will include removing the damaged fuel.

TEPCO understood this important nuance to achieving “cold shutdown” early on this year when it developed its initial recovery plans and developed a new term, “cold shutdown condition,” which applies to how they are bringing the reactors to stable condition. Their definition is as follows:

Temperature of RPV bottom is, in general, below 100 degrees Celsius.

Release of radioactive materials from PCV is under control and public radiation exposure by additional release is being significantly held down. (Not exceed 1 mSv/y at the site boundary as a target.)

By their definition, the Fukushima Daiichi reactors will reach “cold shutdown condition” once they are below boiling point and are no longer releasing significant amounts of radiation into the atmosphere. This new definition, thus, has an important distinction between the more commonly used “cold shutdown,” which typically takes place at a nuclear plant under normal conditions.

Reaching “cold shutdown conditions” at Fukushima Daiichi, however, has been an extremely difficult task for TEPCO workers given the conditions at the site and is a very significant milestone in their recovery efforts. TEPCO expects to reach this condition in just a few weeks by the end of 2011.

Graphic: Schematic of Reactor Design at Fukushima Daiichi

Fluor Invests in NuScale

You know, it’s kind of sad that no one is willing to invest in nuclear energy anymore. Wait, what? NuScale Power celebrated the news of its company-saving $30 million investment from Fluor Corp. Thursday morning with a press conference in Washington, D.C. Fluor is a design, engineering and construction company involved with some 20 plants in the 70s and 80s, but it has not held interest in a nuclear energy company until now. Fluor, which has deep roots in the nuclear industry, is betting big on small-scale nuclear energy with its NuScale investment. "It's become a serious contender in the last decade or so," John Hopkins, [Fluor’s group president in charge of new ventures], said. And that brings us to NuScale, which had run into some dark days – maybe not as dark as, say, Solyndra, but dire enough : Earlier this year, the Securities Exchange Commission filed an action against NuScale's lead investor, The Michael Kenwood Group. The firm "misap...

Wednesday Update

From NEI’s Japan micro-site: NRC, Industry Concur on Many Post-Fukushima Actions Industry/Regulatory/Political Issues • There is a “great deal of alignment” between the U.S. Nuclear Regulatory Commission and the industry on initial steps to take at America’s nuclear energy facilities in response to the nuclear accident in Japan, Charles Pardee, the chief operating officer of Exelon Generation Co., said at an agency briefing today. The briefing gave stakeholders an opportunity to discuss staff recommendations for near-term actions the agency may take at U.S. facilities. PowerPoint slides from the meeting are on the NRC website. • The International Atomic Energy Agency board has approved a plan that calls for inspectors to evaluate reactor safety at nuclear energy facilities every three years. Governments may opt out of having their country’s facilities inspected. Also approved were plans to maintain a rapid response team of experts ready to assist facility operators recoverin...

Nuclear Utility Moves Up in Credit Ratings, Bank is "Comfortable with Nuclear Strategy"

Some positive signs that nuclear utilities can continue to receive positive ratings even while they finance new nuclear plants for the first time in decades: Wells Fargo upgrades SCANA to Outperform from Market Perform Wells analyst says, "YTD, SCG shares have underperformed the Regulated Electrics (total return +2% vs. +9%). Shares trade at 11.3X our 10E EPS, a modest discount to the peer group median of 11.8X. We view the valuation as attractive given a comparatively constructive regulatory environment and potential for above-average long-term EPS growth prospects ... Comfortable with Nuclear Strategy. SCG plans to participate in the development of two regulated nuclear units at a cost of $6.3B, raising legitimate concerns regarding financing and construction. We have carefully considered the risks and are comfortable with SCG’s strategy based on a highly constructive political & regulatory environment, manageable financing needs stretched out over 10 years, strong partners...

NEI Nuclear Notes

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