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Improving the Safety of Soviet-Designed Nuclear Power Plants
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Overview of the Cooperative Safety Work

The U.S. Department of Energy conducts a comprehensive, cooperative effort to reduce risks at Soviet-designed nuclear power plants. In the host countries--Armenia, Ukraine, Russia, Bulgaria, the Czech Republic, Hungary, Lithuania, Slovakia, and Kazakhstan--joint projects are correcting major safety deficiencies and establishing nuclear safety infrastructures that will be self-sustaining. (See the Timeline for this effort.)

The joint efforts originated from U.S. commitments made at the G-7 conference in 1992. Amid heightened international concern about Soviet-designed reactors, world leaders agreed to collaborate with host countries to reduce risks at the older reactors. Since that time, U.S. efforts have expanded to include urgently needed safety work at 20 nuclear power plants with 65 operating reactors. The work is conducted in cooperation with similar programs initiated by Western European countries, Canada, and Japan, as well as international organizations such as the Nuclear Energy Agency of the Organization for Economic Cooperation and Development, the International Atomic Energy Agency, and the European Bank for Reconstruction and Development.

Nuclear Power Plants Participating in the Cooperative Effort to Improve Nuclear Safety



The cooperative effort to improve safety at Soviet-designed nuclear power plants carries significant benefits.

  • It reduces the likelihood of a nuclear accident that could destabilize new democratic governments, require a massive influx of international aid, and threaten the viability of nuclear power worldwide.

  • It promotes a stable business climate for international investments in countries with Soviet-designed reactors.

  • It provides protection for Europe's public, economic, and environmental health and for U.S. citizens in Europe. As was clear after the 1986 Chornobyl accident, the effects of a nuclear disaster extend beyond international borders. More than 60,000 square miles of land were heavily contaminated in Ukraine, Belarus, and Russia. Neighboring European countries were contaminated, and fallout was detected in the United States.

Safety Objectives

The United States supports host countries in their efforts to reduce the most serious risks at Soviet-designed nuclear power plants. The primary objectives include improving plants' physical operating conditions, installing safety equipment, developing improved safety procedures, establishing regional centers for training reactor personnel, installing simulators for training control room operators, conducting in-depth safety assessments, and addressing the extraordinary problems at Chornobyl. A further priority is developing regulatory and institutional frameworks for plant design, construction, and operation that are in keeping with international practices.



Technology Transfer

The term technology transfer refers not just to the delivery of hardware but to passing on knowledge, processes, and methodologies. The goal is to establish an infrastructure in each country that supports the safe operation and maintenance of nuclear power plants.
The U.S. Department of Energy's Office of Nuclear Energy, Science and Technology manages U.S. involvement in the cooperative work. The Pacific Northwest National Laboratory in Richland, Washington, provides technical leadership, with assistance from other U.S. national laboratories, U.S. businesses, and host-country nuclear power plants and scientific organizations.

U.S. specialists work in accordance with the guidance and policies of the U.S. Department of State and the U.S. Agency for International Development and in close collaboration with the U.S. Nuclear Regulatory Commission.

U.S. specialists have established working agreements with organizations in the eight host countries, including key government agencies, scientific institutions, engineering and design organizations, and the nuclear power plants.

More than 50 U.S. commercial firms are providing equipment, training, expert services, and technology transfer, as indicated on the flowchart showing the participants and linkages.

Historical Issues

The safety problems in Soviet-designed reactors have several underlying causes. The most significant is the historical isolation of the plants' nuclear operators, designers, and regulators. In the closed society of the Soviet Union, these personnel could not exchange information or technology with the international nuclear community and had limited interaction even with their counterparts in Soviet countries.

Another significant cause was a secondary emphasis on safety. Goals for low-cost production of electricity often outweighed safety goals. Regulatory bodies responsible for enforcing safety standards were ineffective, especially when their safety directives ran counter to production goals.

The new governments of Armenia, Ukraine, Russia, and Central and Eastern Europe have invested millions of dollars toward improving the safety of their nuclear power plants. However, their economic and technical resources are insufficient to address many of the risks.


Reactor Types

Two basic designs, called RBMK and VVER, were used to build 59 of the 65 reactors addressed in the cooperative safety efforts.

An RBMK reactor uses graphite to moderate neutrons--or slow down the nuclear chain reaction. The nuclear fuel is contained in about 1,700 pressure tubes. Cooling water passes through the tubes, where it is boiled by the nuclear heat to produce steam. The steam is routed to a turbine generator, which produces electricity.

A number of problems are inherent in RBMKs. If several pressure tubes rupture simultaneously, the force will raise the reactor lid, releasing radioactive fission products. An RBMK reactor is susceptible to power instabilities. Increased boiling can boost power levels, creating an uncontrolled nuclear reaction. The older RBMKs lack a modern containment system to prevent release of radioactive materials to the environment. The RBMK's emergency core-cooling system, fire-protection system, and electronic control-and-protection system do not meet international standards.

Fourteen RBMK reactors are in operation. The Chornobyl reactor that exploded in 1986 was an RBMK.

VVER reactors use pressurized light water for core cooling and to moderate the nuclear chain reaction. Forty-five VVER reactors are in operation. There are three principal models.

The earliest, the VVER-440/230, has a limited containment system and virtually no emergency core-cooling system. Its backup safety systems, fire-protection systems, and electronic control-and-protection systems are inadequate.

The VVER-440/213 reactor is an enhanced version of the 230 model. It has an emergency cooling system and a "bubbler condenser tower" that provides a measure of containment. Fire protection and electronic control-and-protection systems are inadequate.

The VVER-1000, the largest and newest model, meets most modern safety standards. It has an emergency core-cooling system and a containment building. However, its fire protection and electronic control-and-protection systems have shortcomings.

In 1996, two Russian plants with neither RBMK nor VVER reactors requested U.S. collaboration in safety improvements. The Bilibino plant has four LWGR-12 light-water-cooled, graphite-moderated reactors. The Beloyarsk plant operates a BN-600 breeder reactor.

In 1997, the Asian nation of Kazakhstan requested U.S. collaboration in improving safety at its Soviet-designed BN-350 fast-breeder reactor. The nuclear power reactor is in the city of Aktau.

Reducing Risks as Reactors Continue to Operate

Western safety specialists have encouraged the host-country governments to shut down the most unsafe reactors. However, most will continue to operate for the foreseeable future.

The reactors provide urgently needed electrical power, ranging from 13 percent of Russia's power supply to 44 percent of Ukraine's and 83 percent of Lithuania's. The international community is encouraging the development of alternative power sources, but the transition could take 10 years or more and will require a great deal of money, which the host countries can ill afford.

Abrupt closure of nuclear power plants would carry a high cost in human terms--the loss of thousands of jobs and an increase in electricity prices. These socioeconomic changes could have drastic consequences in fragile democracies that already are struggling to stabilize their economies.

The only economically viable solution is to work with the host countries to reduce the risk of accidents until they can shut down reactors or bring them into compliance with international practices.


Activities to Reduce Risk and Improve Safety

Since the inception of these efforts in 1992, U.S. specialists have initiated more than 150 joint projects. Many projects have reduced risks immediately by decreasing the possibilities of equipment malfunction and operator error.

Projects are organized into six areas, which are referred to as work elements.

  • Management and operational safety projects increase the safety of day-to-day operations by training operators, establishing safe operating procedures, and transferring maintenance technologies and training.

  • Engineering and technology projects reduce operating risks by upgrading the physical safety systems of nuclear power plants. Projects are focused on improvements in fire safety, radiation confinement, and reactor safety systems.

  • Plant safety assessment projects improve the abilities of designers, operators, and regulators to evaluate the safety of their plants through the use of internationally accepted methodologies and computer analysis codes.

  • Fuel cycle safety projects improve the handling and storing of reactor fuel and the operation of nuclear-fuel-cycle facilities.

  • Nuclear safety regulatory and institutional framework projects address the need for effective regulatory systems in countries with Soviet-designed reactors.

  • Chornobyl initiatives involve four major efforts:

    • establishment of a research center in the city of Slavutych, near the Chornobyl site

    • reduction of risks at Chornobyl's operating Unit 3 reactor

    • support of an international effort to prevent collapse of the shelter around Chornobyl's ruined Unit 4 reactor, suppress the radioactive dust inside the shelter, and protect shelter workers from radioactive and industrial hazards

    • development of technical strategies for decommissioning the Chornobyl plant.


Key Accomplishments

Technology Transfer

U.S. and host-country organizations are conducting joint projects to manufacture safety equipment, perform safety assessments, and use advanced technology in staff training. After U.S. training, a company in Ukraine and another in Russia are manufacturing more than 800 fire doors that satisfy international standards. The doors are for four plants. U.S. contractors are collaborating with four countries to develop or upgrade 14 control room simulators for training reactor operators. The United States is transferring computer analysis codes and methodologies that enable host-country specialists to assess plant safety, identify risks, and set priorities for safety upgrades.


With U.S. support, Ukraine and Russia each have established a successful nuclear training center to accelerate the transfer of skills and safety information. U.S.-trained instructors at these centers have in turn trained more than 3,000 workers. The instructors developed and conducted job-specific maintenance and operations courses, along with courses in employee safety and supervisory skills.

The instructors are now working with U.S. experts to expand the training program to other Ukrainian and Russian plants. Development and presentation of site-specific training courses at those plants is under way.

Emergency Operating Instructions

U.S. specialists have completed the transfer of skills for developing symptom-based emergency operating instructions to pilot plants in Ukraine, Russia, and Central and Eastern Europe. Symptom-based instructions enable control room operators to stabilize a reactor quickly during an abnormal event. The time saved can prevent disaster.

Safety Maintenance Technologies

The United States has transferred pipe lathe/weld-preparation machines to the five plants with RBMK reactors, enabling workers to cut and replace flawed pipes with precision. Previously, workers cut pipes by hand, increasing the difficulty of welding in new pipe and thus the risk of subsequent leaks that could lead to a loss-of-coolant accident.

Control Room Operator Prevents a Disaster

In spring 1995, a control room operator prevented an accident at a Soviet-designed reactor.

The operator had participated in an exchange visit to the United States, where he watched a crew respond to a hypothetical disaster on a plant simulator. The "accident" depicted loss of cooling water to the reactor core. The operator also had worked with U.S. specialists to develop symptom-based emergency operating instructions for controlling accidents at his own plant.

Then, during routine testing at his plant, a valve for the reactor cooling system stuck open. The system rapidly depressurized. Cooling water stopped flowing to the reactor core.

Operating crews tried to determine the cause of the crisis in order to restore the flow of cooling water. They were unsuccessful, and the nuclear fuel began to overheat.

The operator who had worked with U.S. specialists intervened. Based on his knowledge of emergency operating instructions and his experience watching a U.S. crew deal with a similar situation, he decided to use reactor head vents to restore cooling. Water returned to the reactor core, and the plant was brought to cold shutdown. The abnormal event ended before fuel damage occurred.

The United States has transferred valve-seat resurfacing equipment to repair leaking valves, vibration monitoring and shaft alignment systems to detect and correct imbalance and shaft misalignment in rotating machinery, and nondestructive examination equipment to find flaws in pipes and other key reactor components before they cause problems.

Engineered Safety Upgrades

The United States has supplied basic fire protection equipment to plants in Armenia, Ukraine, Russia, and Bulgaria. Russia's Kola and Kursk plants and Bulgaria's Kozloduy plant have received backup power systems to supply vital electricity during emergency shutdowns. Russia's Kursk plant has received a mobile pumping unit for emergency water supplies.

Control room operators at Kursk now have a safety parameter display system, which enables them to assess abnormal conditions rapidly and take corrective actions. Development of safety parameter display systems for 14 other reactors is under way.

With U.S. support, Kola staff have substantially reduced leaks in the radiation confinement system. Bulgaria's Kozloduy plant has received thermal imaging hardware that identifies hazardous "hot spots" in the plant's electrical system. U.S. and host-country experts have defined methodologies for conducting fire hazards analyses at Soviet-designed reactors, and pilot analyses are under way at Russia's Smolensk plant and Ukraine's Zaporizhzhya plant.

Spent Fuel Storage

At the Zaporizhzhya plant in Ukraine, cooling ponds for storing spent fuel rods are nearly full. The United States has delivered equipment and trained Ukrainian personnel to build and regulate a safe, modern dry-cask storage system. The system will reduce the need to send spent fuel to Russia for reprocessing.

Chornobyl Initiatives

U.S. and Ukrainian specialists established the Chornobyl Center for Nuclear Safety, Radioactive Waste and Radioecology in the town of Slavutych, near Chornobyl. Joint projects in data analysis, spent fuel management, and reactor closure are under way. The United States provided a satellite communications system, which has given the Center reliable telephone access to the rest of the world, as well as electronic mail service, videoconferencing capability, and electronic access to the information databases of partnering organizations.

The United States is reducing risks at Chornobyl's operational Unit 3 reactor with training and modern equipment for maintenance and fire protection. U.S. and Ukrainian specialists have developed procedures for safer day-to-day operations.

The International Shelter Project, in which the United States participates, has developed the Shelter Implementation Plan, which details measures to prevent collapse of the shelter around the ruined reactor Unit 4, to construct a new shelter to cover the current one, and to protect workers and the environment. U.S. experts provided the primary technical support for developing the plan. The United States is providing shelter workers with equipment and training for suppressing the radioactive dust inside the shelter, reducing their radiation exposure, and improving industrial safety.

Performance Measurement

The U.S. team has established end points that define the successful completion of projects in each technical area. A project reaches its end point when the host country, its nuclear support organizations, and its nuclear power plants can sustain safety achievements and build upon them to meet internationally accepted nuclear safety practices. These end points are measurable, achievable targets.

The U.S. team defined the end points by weighing several factors for each project: its safety impact, its cost effectiveness, the time needed to achieve results, and the ability of the host country to sustain the safety achievements over the long term.

Future Direction

With their joint efforts, the United States and the host countries are reducing risks at Soviet-designed nuclear power plants.

U.S. personnel will continue working to meet the following goals:

  • Transfer modern technologies and methods to enable each host country to establish and maintain a strong safety infrastructure.

  • Engender a nuclear safety culture in which safety takes priority over power production.

  • Provide opportunities for U.S. commercial companies to establish joint ventures and ongoing nuclear safety partnerships with the host countries.

  • Accelerate efforts to reduce risks and support decommissioning at Chornobyl.

  • Promote safer plant operations over time.

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