Nuclear Power Plants Present Unique Transmission Interconnection Challenges

Dale Landgren, Vice President and Chief Strategic Officer, American Transmission Co.

THE HEADLINE IN THE APRIL 2006 National Geographic read, "It's controversial. It's expensive. And it might just save the Earth." The subject was nuclear power and discussion of its comeback has been a featured topic across the news media. One year after this article was published, the Tennessee Valley Authority approved the first nuclear reactor to come online nationally in more than a decade, when it authorized restarting unit 1 of the Browns Ferry nuclear power plant in Athens, Alabama. Since that time, the Nuclear Regulatory Commission (NRC) expects applications for as many as 11 new units in 2007 and for as many as 28 by the end of 2009.

Interest in nuclear power is growing across the country for several reasons:

*Concerns about fossil fuel emissions' impact on the climate

*Rising prices for oil and natural gas

*Nuclear power's potential to supply electricity to large populations

*An increasing desire to make the nation less dependent on foreign energy sources

The prospect of a resurgence of nuclear power plants raises a long list of engineering, environmental, regulatory, and process coordination issues for nuclear plant developers, transmission owners and regulators to address. Interconnecting power plants to the transmission grid is a key component of bringing them online and more so than other types of power generation, nuclear plants present a unique and complex set of engineering and regulatory challenges for industry and regional transmission organizations. Because of the length of required lead times (10 years or more and especially weighted to the pre-construction-approval side) and the breadth of coordination required, we believe that a deliberate and engaged approach to the planning process will be a critical ingredient in ensuring successful and timely siting and interconnection of new nuclear power plants.

American Transmission Co., which owns and operates the transmission system in portions of Wisconsin, Michigan, and Illinois, has three nuclear units at two sites with approximately 1,600 megawatts of capacity interconnected into our 13,000 megawatt system. In electric transmission line siting, since ATC's inception we have used an inclusive and up-front approach to stakeholder engagement that helps smooth the process and reduce delays. By investing time and resources in addressing issues and concerns of local officials, community organizations, local utilities and regulators at the front end of the transmission line siting process, we have successfully secured approval for major projects with minimal opposition. We are near completion on the largest transmission line project under construction in the country, the 210-mile Arrowhead to Weston 345 kilovolt line linking Duluth, Minnesota to Wausau, Wisconsin. We also have two 50-mile 345 kV lines approved and under construction in central Wisconsin. While the stakeholders involved in connecting nuclear power plants to the transmission grid may comprise different players, we believe that our corporate philosophy of extensive up-front, informal collaboration will prove to be a critical component in managing long-term coordinated efforts to safely interconnect new nuclear power plants.

Since the completion of construction of the last nuclear plant in the United States, experiences on both sides of the interconnection have produced new recommendations, requirements and regulation from the NRC, the North American Electric Reliability Corporation, and the Nuclear Power Operators' Association. These new expectations necessitate reconsideration of prior planning methods—methods that may have been sufficient when many of the existing nuclear plants were originally licensed.

Further, reactor protection systems, such as emergency core cooling and containment cooling, must be able to receive power under normal, abnormal and accident conditions. Without sufficient satisfaction of nuclear plant safety requirements via transmission supply of offsite power, nuclear plants may be forced to come offline. Changes in nuclear power plant output can also impact the voltage and stability of the surrounding transmission grid. For the safety of the plants as well as the grid itself, nuclear-transmission interconnections must include an appropriate configuration of transformers, switchyards, control systems, battery systems and supporting back-up generators. These system needs present unique challenges to connecting large new nuclear power plants to the transmission grid.

More Coordination and Long Lead Times Needed

Potential developers of new generation have significantly different time horizons, depending on the fuel source. Wind generators can identify a site, order equipment and construct the generation in a relative short span of several years (although transmission interconnection is becoming a much larger issue, as noted by a recent FERC technical conference on this issue). Natural gas peaking units can similarly be sited and constructed in a short time span, with intermediate or base load generation taking somewhat longer. Coal-fired generation can take up to 7-10 years to get through regulatory approval, siting and construction. While the country has no recent experience with new nuclear generation, it is expected to take 10-15 years from planning through authorization and design. These lead times mean that nuclear developers may need to work outside the bounds of official processes, whose lead times may be too short for nuclear plants. This scenario can be managed by providing a high level of attention to informal collaboration above and beyond the letter of the process.

Generators that wish to interconnect to the grid must enter a generation interconnection study queue years in advance of their in-service date so that transmission connections can be studied, planned, sited and constructed accordingly. If a transmission provider has specific queue "hurdles" in place that are meant to ensure a developer's intention to construct (such as a demonstration of relevant permits, site control and/or equipment contracts), the transmission provider will need to correctly balance non-discriminatory treatment of queued requests with the project development limitations experienced by the nuclear power plant builder.

In the Midwest ISO region, generator owners must make a request to the Midwest ISO to interconnect to the system. The Midwest ISO, however, restricts interconnection request in-service dates to a seven-year horizon. In other words, the nuclear power plant builder will need to demonstrate "that engineering, permitting and construction of the Generating Facility will take longer than the regional expansion planning period"1 to enter the queue with an appropriate in-service date for the proposed plant.

Multiple Issues must be Studied

On behalf of and under contract with the Midwest ISO for interconnection studies, ATC examines the impacts that additions or changes in electricity generation output have on the transmission system and surrounding generating facilities. The typical impacts examined in an interconnection study are those due to the additional fault current and continuous power flow injected by the new plant into the transmission system, as well as any unacceptable dynamic response of the system created by the presence of the proposed power plant.

For the nuclear power plant, however, these typical studies may need to be expanded due to additional considerations, which, in turn, can lengthen the study process. Due to the nature of the fuel source, nuclear power plants contain specific safety systems that are designed to protect the plant, its employees and the public. Some of these safety systems monitor the transmission grid for an indication that the grid can no longer reliably serve the power plant functions protecting the nuclear core.

Operation under the relevant procedures or operation of the automatic protection systems may conclude in the disconnection of the nuclear power plant from the transmission grid. Besides the lost opportunity costs and regulatory scrutiny for the power plant operator, the transmission system and its customers suffer the loss of a significant base load power plant, often resulting in the dispatch of higher cost generating units. Therefore, additional studies to coordinate the required steady-state and dynamic transmission and plant voltages are warranted, even under transmission or generation contingency scenarios that are more severe than typically examined for a power plant interconnection.

The system impacts and other operating envelope issues identified often require modifications or expansion of transmission facilities. Since the nuclear power plant builder may be limited in potential siting locations to either existing nuclear power plant sites or locations remote from large population centers, the transmission upgrades needed to integrate a large, new nuclear power plant may be substantial. If substantial transmission system expansion is required, the nuclear power plant builder may find that the transmission owner faces equally long (i.e. seven to ten years) lead times for completion of all required facilities.

Nuclear investment and regulations require a greater degree of transmission security than other generation locations. More thorough planning, including double contingencies, common mode outages, voltage regulation limits, and accounting for planned outage conditions, must be performed for a nuclear plant to be sited. Nuclear sites are typically remote from urban areas and therefore will probably need significant transmission investment. However, they may be able to benefit from some transmission infrastructure near brown site and existing (or retired) nuclear locations.

Funding of Transmission Interconnections

Under FERC interconnection rules, the generator seeking interconnection must pay for the required studies. If new transmission facilities are required (which, for larger scale generation, whether nuclear or other, is likely), some significant financial obligations can be incurred by the generator. In the Midwest ISO, generators must finance the construction of the facilities, and when the generator goes in service, the transmission owner will reimburse 50% of those costs (note that if the generation is abandoned, there is no reimbursement). ATC recently received approval from FERC to reimburse 100% of these costs. Given the long lead time for nuclear generation and the potential for significant transmission additions to interconnect, the developer of nuclear units will have to accommodate the need for this financial obligation.

Market Impacts on Nuclear Development

Organized markets take a marginal cost approach rather than an embedded cost approach to paying for generation output, so the owners of baseload plants like nuclear have a need to be able to sell into the market whenever possible. The result is that transmission constraints around nukes are unacceptable from a cost standpoint. Although nuclear plants have some ability to ramp their output, they are typically "price takers" and the Midwest ISO does not ramp them to set LMPs. As price takers, for short time periods they would be willing to accept LMPs below their production costs, possibly even negative LMPs. Over longer term periods, if local transmission congestion were to depress LMPs, it may significantly impact their profitability.

Conclusion

Environmental issues like climate change and economic security issues are likely to lead to a significant change in the mix of generation that is built to meet the country's electricity needs over the next few decades. Nuclear power currently supplies roughly 20 percent of the nation's electricity with no greenhouse gas emissions. This comes as electricity demand is projected to jump more than 40 percent by 2030—not including potential new demand from a shift to plug-in hybrids and other forms of electric cars. To meet this growing demand for energy, policy makers will need to address or support a fuel portfolio that can safely meet this growing demand for electricity in a clean manner. If nuclear power is among the set of solutions, it will be more important than ever for generation owners, transmission providers and state regulators to collaborate in planning for these facilities early enough to effectively meet the challenges unique to connecting this type of generation to the transmission grid.

1(MISO TEMT Attachment X, Section 3.3.1)