Development of Vogtle Electric Generating Station Units 3 and 4—the first new nuclear power plant units in the U.S. in decades—has generated considerable excitement. The next generation of nuclear plants, represented by these units, includes at least two major improvements: the use of passive safety systems and a reliance on digital control systems. The latter represents a gigantic leap in modernization and a fundamental change in control of the plant.

Working out of a small city of trailers, more than 1,500 employees are busy bringing life to Southern Nuclear Operating Co.’s Units 3 and 4 of Vogtle Electric Generating Station (Plant Vogtle), located approximately 45 minutes south of Augusta, Georgia. Earth-moving equipment travels in a continuous line around two large excavations that will hold the foundations of these two new units (Figure 1), and erection of the modular assembly building is in progress (Figure 2). At the same time, staff are busy finalizing the Westinghouse Advanced Passive (AP) 1000 design and its instrumentation and control (I&C) systems.

1. Southern powerhouse. Excavation for the foundations of Plant Vogtle Units 3 and 4 is in progress. The two new units are the first to be constructed in the U.S. in decades. Courtesy: Southern Company

2. On the rise: next-generation nuclear plants. Construction crews are shown erecting the Modular Assembly Building, which will be used to produce modular assemblies during construction of Vogtle Units 3 and 4. Vogtle Units 1 and 2 are in the background. Courtesy: Southern Company

As with any major endeavor, in addition to the excitement there are also challenges. This article provides information about the progress and special concerns related to the I&C design for Vogtle Units 3 and 4.

Developing a Setpoint Control Program

The handling of setpoints (the target values that a protection control system responds to) has raised several questions for new plants. However, the area that has received the most attention so far is the removal of setpoints from the Technical Specifications in the Technical Specification Traveler Form 493 (TSTF-493), which relocates trip setpoints to a licensee-controlled program.

The TSTF allows the Limiting Trip Setpoint, the Nominal Trip Setpoint, and/or the allowable values to be relocated to a licensee’s setpoint control program. Combined construction and operating license (COL) applicants or licensees will describe their facilities’ setpoint control programs in Section 5.0 of the Technical Specifications, which details the “Administrative Controls.” This section also will contain a reference to the licensee’s or COL applicant’s setpoint methodology, which has been approved by the U.S. Nuclear Regulatory Commission (NRC).

Simply stated, TSTF-493 was born out of necessity. While a preliminary setpoint study has been drafted, the instruments have not been selected for the plant. Thus the NRC could not approve the Limiting Trip Setpoints and Allowable Values in the Technical Specifications because the supporting data for that setpoint study could not be validated. The NRC has reviewed and accepted the proposed setpoint methodology. In order to prevent slippage in the licensing schedule for Vogtle Units 3 and 4, all parties agreed that the best course of action was to adopt the guidance in TSTF-493. By shifting responsibility for preparing the setpoint list to the COL applicant, the NRC could approve the Technical Specifications and later validate the setpoint study.

It should be noted that the final version of TSTF-493 is still under review, but the basic guidance was used to resolve this issue. In the end, this handling of the setpoint issue seems to be a good compromise for all of the parties involved.

The incorporation of TSTF-493 has the potential to be a very positive change for Vogtle Units 3 and 4. Southern Nuclear already has a fleet setpoint control program, which is based upon the model in the Institute for Nuclear Power Operation’s (INPO’s) Engineering Program Guide for Setpoint Control. The program is described in a fleet procedure and centrally locates all of the approved setpoint methodologies for our existing units at Farley, Hatch, and Vogtle. In addition, the program provides guidance on gathering and trending setpoint-related data. So the addition of the Limiting Trip Setpoint, Nominal Trip Setpoints, and/or Allowable Values for Vogtle Units 3 and 4 is just the next logical step for the program.

Besides being easy to implement, the main advantage of incorporating TSTF-493 will be that Southern Nuclear can change one of these setpoints using the 10 Code of Federal Regulations (CFR) 50.59 process. Thus, if one of these setpoints needs to be modified in the future, prior NRC approval is no longer required unless the results of the 10 CFR 50.59 evaluation require it. For licensees or COL applicants to gain this additional control, the NRC will periodically audit the program, and the NRC must be notified of any changes to the setpoint control program. The licensee or COL applicant will also have to follow an NRC-approved setpoint methodology.

The incorporation of this TSTF will also create a need for licensees or COL applicants to have trained and knowledgeable staff members with access to the design bases and assumptions behind the setpoint methodology to make prudent decisions regarding setpoints. Despite the increased responsibility assumed by Vogtle Units 3 and 4 personnel, this change is considered a very positive one.

Human Factors Engineering

Easily the brightest spot so far in the development of the two new units’ I&C program has been the human factors engineering (HFE) area. The reason that HFE is considered a success is the close cooperation between the AP1000 vendor, the AP1000 utilities’ operations committee, and the AP1000 utilities’ I&C committee. Multiple workshops have been held and numerous challenges have been resolved successfully. The types of concerns include display color schemes, layouts, alarming functions, short-form naming conventions, test plans, and even the need for separate restrooms for male and female operators. Although this list is not exhaustive, it does provide an indication of the types of concerns that have been discussed.

One action that the AP1000 vendor has taken is worth singling out. A simplified HFE guidance document for package system vendors was developed. In the past, many organizations have struggled with how to effectively provide HFE guidance. In some cases, the result was an addendum to a specification that was simply too thick and too exhaustive to be of any use to suppliers. At the other extreme, HFE guidance often was too sketchy or even nonexistent. The hope is that this simplified document will provide the right mixture of practical information and guidance.

Southern Nuclear recognizes the need in the future for developing an engineering program for human factors. The company currently has a fleetwide Emergency Operating Facility and will add a common Technical Support Center for all four units at Plant Vogtle. The responsibility of performing a human factors review of these facilities is within Southern Nuclear’s scope. In addition, we recognize that with digital control systems it is incumbent upon us to provide a human factors review whenever changes occur to the displays for any of the digital systems.

While planning for these activities, a need for HFE training has become evident. A couple of possible options are being actively pursued. The University of Michigan conducts a well-respected two-week class each year, and the Electric Power Research Institute (EPRI) has a project to develop training in this area. Other options may be available in the future, but these are the two most viable ones at this time.

Addressing Electromagnetic Interference

Electromagnetic interference (EMI) did not become an issue until after most existing nuclear power plants were constructed. For Vogtle Units 3 and 4, the issue is being addressed early in the design (see sidebar). Southern Nuclear is working with EPRI and other AP1000 utilities to provide practical solutions in this area.

Revision of EPRI Technical Report TR-102323. One of the ways that Southern Nuclear is addressing EMI concerns is by teaming with the industry through EPRI, which is considered a leader in this area. Using experts from around the industry, EPRI published Technical Report TR-102323, Guidelines for Electromagnetic Interference Testing in Power Plants. The primary benefit of this landmark report was its guidance for the testing of components. Now EPRI has an initiative under its Advanced Nuclear Technology program to revise this report. The major goals of this new initiative are to:

  • Develop guidance that limits the need for exclusion zones for components, including wireless equipment.
  • Develop guidance for a plantwide frequency spectrum management plan.
  • Recommend a strategy to programmatically address EMI during various life-cycle phases of equipment such as design, specification development, purchasing, planning, and maintenance.
  • Provide guidance related to terminations, which will reduce EMI concerns.

Southern Nuclear wants to leverage this guidance to address EMI issues for Vogtle Units 3 and 4.

Focusing on Important Frequencies. Another way that Southern Nuclear is addressing EMI is through an AP1000 utility engineering committee. This committee has been working with the AP1000 vendor to ensure that EMI standards and testing processes are commonly applied throughout the project. Also, testing frequencies have been increased from 1 gigahertz (GHz) to 10 GHz.

In order to make the testing meaningful, increased attention is being given to any anomalies that may occur within critical frequency bands. These critical frequency bands are areas where the U.S. Federal Communications Commission has allocated frequencies for common uses. If anomalies do occur in these regions, then they will be given priority over anomalies that do not occur in these critical frequency bands. This ensures that attention is focused on the most important areas.

Integrating Cyber Security

No other recent issue has dominated the attention of the nuclear I&C industry like cyber security. It often seems that cyber security is the first, second, and third priority. Vogtle Units 3 and 4 are not immune to this threat. A great deal of time, travel, and expense have been spent in developing Vogtle Units 3 and 4’s cyber security plan. Because Vogtle Units 3 and 4 are the AP1000 reference plant, the plan for these units is essentially the plan for the first wave of AP1000 units in the U.S. Thus, it has been important to develop a consensus approach to cyber security among current AP1000 applicants.

After several meetings with the NRC, the writing team agreed to submit the NRC RG 5.71 Cyber Security Plan in January 2010 with a few exceptions. The breakthrough occurred after the NRC understood the need for these exceptions. The writing team had also considered using the NEI 08-09 template that the NRC stated was an option. The NRC staff also stated that using the NEI 08-09 template would probably result in delay of the COL. After weighing all of the options, the writing team believed that submitting RG 5.71 with exceptions was the only viable option. At the time this article was written in December, review of the cyber security plan for Units 3 and 4 was ongoing. Nevertheless, the writing team and the applicants are optimistic that the NRC will approve the plan.

The program phase is next. A cyber security team will have to be assembled and procedures will need to be written that define the cyber security program based upon the cyber security plan. In addition, the team will need to develop awareness training for personnel in all involved organizations (Southern Nuclear and vendors). Procurement, design, information technology, security, licensing, and construction staffs will need to be told about the commitments made in the cyber security plan.

Southern Nuclear continues to pursue teaming arrangements to support efficient development of the cyber security program for Vogtle Units 3 and 4. Teaming with other AP1000 applicants when evaluating the critical systems and critical digital assets is an example of that teamwork. Furthermore, we plan to work with our existing nuclear fleet to prevent duplication of tasks. There is also a benefit in communicating with Southern Company’s fossil fuel cyber security staff to ensure that we share our best practices. In the end, sharing and communicating with these other organizations is beneficial for everyone involved.

Managing a Growing Staff

INPO has developed a document entitled “Principles for Excellence in Nuclear Project Construction.” Principle #1 states that “Leaders demonstrate alignment on a commitment to excellence.” Though this may seem like an odd topic for this article, it is one that has received a great deal of attention in the nuclear power industry. INPO defines “leaders” in this context to be executives and managers, but the impact of this principle extends to all levels of leaders in the entire organization. Several examples of alignment and the reasons for the changes are provided below.

Three years ago, the Nuclear Development Engineering organization for Southern Nuclear grew from one person to four people. The author was part of that initial staffing increase and was given the responsibility of oversight for I&C, electrical, information technology, communications, human factors engineering, configuration management, and any other duty as assigned. Today the engineering group contains more than 20 people. The organization has had to be aligned to accommodate the increased amount of work and the increased number of people.

In his book Good to Great, author Jim Collins comments that the companies he studied not only got the right people on the team but they also placed them in the right positions. When undertaking a large project such as building a commercial nuclear power plant, it is critical that all of the organizations involved get the right people on the team and get them placed in positions where they can excel. This is especially true when increasing the size of the organization, such as when ramping up for a large project.

A complicating factor is that no new commercial power plants have been built in the U.S. in decades. As a result, there are few people who have construction experience, I&C experience, I&C system installation and start-up experience, and nuclear experience. In some instances, a person may possess experience in all of these areas, but these people are rare. Thus, it is difficult to find people who possess a good mix of these experiences and to place them in positions where they can perform extremely well.

Looking Ahead

Several times a year, someone within the industry will ask me, “Do you think we will really build any new nuclear power plants?” The answer is “yes.” People are genuinely shocked when I tell them just how much progress has been made in the past three years. Even the amount of progress in I&C design is amazing. Even though questions and challenges remain to be resolved, the challenges are not insurmountable. The Vogtle units are becoming a reality. In the end, the goal of safely licensing, constructing, and commissioning the first commercial nuclear power plant in decades in the U.S. is very achievable.

This article is based on a paper presented by the author at the 15th Annual POWID/EPRI Controls and Instrumentation Symposium. â– 

James H. Flowers (jhflower@southernco.com) is I&C engineering supervisor at Southern Nuclear Operating Co.’s Nuclear Development Division.