NUCLEAR POWER | EPC SOLUTIONS LLP

NUCLEAR POWER

Nuclear Power in the Energy Mix

We accept the decision by Germany's political majority to accelerate the phaseout of nuclear power and the transformation of the country's energy supply system. But even under the new circumstances, nuclear power will remain in our energy mix for over a decade. In addition, by enlarging our renewables capacity and by building high-efficiency fossil-fueled generating units (large units and smaller, distributed units), we're helping nations to maintain a secure, affordable, and balanced energy supply.

We works with companies who operate, and have a majority stake in, three nuclear power plants (NPPs) in Sweden: Oskarshamn 1, 2, and 3. The installed capacity of the NPPs in Germany and Sweden for which we have operational responsibility totals about 8 gigawatts. Two of our NPPs in Germany (Würgassen and Stade) were withdrawn from service several years ago for commercial reasons and are currently being dismantled.

Countries other than Germany continue to see nuclear power as a viable option.

Secure the Supply - Reduce Dependency

Europe is rich in ideas, but poor in resources. Currently, more than 50 percent of the energy sources used for power generation have to be imported, and the trend is rising. If the dynamic development continues in the global energy market, energy that is available whenever we need it is something that could soon no longer be taken for granted. Yet a reliable energy supply is the basis for the growth and well-being of any industrial nation.

Given the uncertain political situation in many exporting countries, Europe needs its own and otherwise reliable energy sources. The longer the German nuclear power plants are in operation, the lower our dependence on other energy sources.

Uranium fuel will be available for at least 200 years and comes from politically stable countries like Canada and Australia. Another advantage: Unlike with oil and gas, there are no competing uses for uranium, such as for fuel and heating or as a feedstock in the chemical industry.

Uranium also has a very high energy density, i.e., a very large energy content. One kilogram of natural uranium corresponds to an energy equivalent of about 13,000 liters of oil, or almost 19,000 kilograms of coal. Because of its high energy density, uranium is also easy to transport and can be stockpiled on virtually any scale and for any duration.

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Cost Effectiveness Ensures Competitiveness

Nuclear energy contributes significantly to a low-cost and reliable electricity supply in Europe. This ensures the competitiveness of our economy and the sustainability of an industrial site. The competitiveness of nuclear energy is not affected by rising fuel costs, unlike other energy-conversion technologies. Uranium accounts for only about three to five percent of the electricity-generation costs of a nuclear power plant. This means that fuel price increases have very little impact. Even a doubling of raw materials prices would have hardly any effect on electricity-generation costs.

Climate Precaution from Beginning to End

Each year around 1.4 billion tons of CO2 are released by electric power generation alone. There are also emissions from industry, transport, and household use. Emission of carbon dioxide is the main cause for the so-called "greenhouse effect," which can lead to extreme climate changes. The EU has vowed to cut its CO2 emissions by at least 20 percent by 2020, compared with 1990 levels. Additionally, the EU has declared that it will attempt to reduce CO2 emissions by as much as 30 percent by 2020. However this has been pledged under the condition that other major emitting countries commit to do their fair share under a future global climate agreement.

Even considering the entire life cycle of nuclear energy usage (including, among other things, uranium mining and conversion, reprocessing, power plant decommissioning), the greenhouse gas emissions of 5 to 33 grams of CO2-equivalent per generated kilowatt-hour are comparatively small. Alongside water and wind, nuclear power has by far the lowest CO2 emissions of all energy sources, as the Paul Scherrer Institute of Villingen (Switzerland), among others, has ascertained.

The research institute has studied the sustainability of various energy systems and determined: Nuclear energy, with its positive climate record, outranks such energy sources as photovoltaic, geothermal, and biogas. Other national and international studies also confirm this, for example those of the Öko-Institut and the European Commission. Nuclear plants are thus climate protectors right from the start of uranium mining, through construction and operation, up to disposal and decommissioning of plants back to the green field.

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Incredible Amounts of Energy

Naturally-occurring uranium, as extracted from uranium ore, contains only about 0.7% fissile uranium 235; the remaining 93.9% is non-fissile uranium 238. Uranium in this state is not suitable as fuel for light-water reactors and needs to be enriched to increase the percentage of uranium 235 to three to four percent (with the rest remaining as uranium 238). Once enriched, the uranium is pressed into pellets and placed in fuel rods, which are then welded shut. The fuel rods are then bundled to form fuel elements-ready for use in reactors.

How does Nuclear Fission Work? The nuclei of uranium-235 are bombarded with neutrons. When a uranium-235 nucleus absorbs a bombarding neutron, the result is a highly unstable nucleus, uranium-236.

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Within a fraction of a second this nucleus splits into two fission products. The resulting fragments fly apart at high speed but are quickly slowed down in the uranium's crystal lattice, with the result that the kinetic energy is converted into heat. Neutrons are also released in the fission process. These neutrons (known as 'fast' neutrons) have a very high energy level, too high, in fact, to induce a further fission of uranium-235 and hence start a chain reaction.

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This is why, in LWR reactors, water is used not only as a coolant, but also as a moderator. Moderators effectively reduce the energy (speed) of the neutrons to a level which is suitable for inducing further nuclear fission.

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Conclusion:
In the nuclear power plants operated by E. ON Kernkraft, self-sustaining fission reactions are not possible without water as a moderator.
Reactor Types

We operate two kinds of nuclear power plant in both Germany and Sweden: pressurized-water reactors (PWRs) and boiling-water reactors (LWRs). Both types of reactor use water both as a coolant and as a moderator.

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Pressurized-water Reactor In pressurized-water reactors the water in the primary cooling circuit absorbs the heat released by nuclear fission. This circuit is pressurized to prevent the water from boiling. The primary cooling circuit transfers the heat generated in the reactor to the steam generators, which are connected to the water-steam circuit (secondary circuit). The steam generators form a barrier between the primary circuit and the secondary circuit, thereby preventing radioactive material from escaping from the primary circuit.
Boiling-water Reactor In boiling-water reactors, the pressure is set so that some of the water evaporates while flowing through the reactor core. The resulting steam is separated off and fed directly through to the turbines, which are coupled to the generator. Boiling-water reactors differ from pressurized-water reactors in that the steam produced by the former is slightly radioactive. Consequently, it is possible for radioactive deposits to build up in the steam lines, turbines, and condenser and condensate lines. For this reason special safety facilities are installed in the turbine rooms of boiling-water reactors.

Power Station Safety


The use of nuclear energy for power generation is only feasible if we can guarantee the safety of people and the environment.

All of our safety measures are based on a safety philosophy aimed at protecting people and the environment from radioactive emissions from nuclear power plants.

Automated processes

'Passive safety features' are the first-line safety mechanisms used in nuclear power plants. Passive safety structures seal in the radioactive materials contained in the reactor core under all operating conditions (including accidents), keeping them separate from the outside environment. The fuel pellets themselves, the fuel-rod casings, reactor pressure vessel, biological shield, steel containment structure, and outer reinforced concrete shell of the reactor building are the six most important passive safety features.

Maximum physical shielding The passive safety features are supplemented by a comprehensive range of automated 'active safety features.' The reliability of these features is based on their multiple redundancies, and on the fact that they operate independently of each other in separate locations.

For example, each nuclear facility has its own power supply. And the reactor cooling systems are designed to ensure that the heat generated by the reactor can be reliably removed under any operating conditions-even in the event of a very unlikely malfunction, such as a breach of a primary coolant line. The electronic reactor protection system is the 'nervous system' controlling all active safety systems. It constantly monitors and compares all the key operating parameters of the plant. Thus, if a parameter reaches a limit value, the reactor protection system automatically triggers the necessary protection measures without any need for input from plant operating personnel. For example, if necessary, the protection system may initiate a rapid shutdown and after cooling procedure.

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Why Do We Use Interim Storage?

In German nuclear power plants, interim storage facilities for fuel elements are one of the building blocks of the chain of waste disposal. At each nuclear power plant inspection, about a quarter of the fuel elements are replaced by new ones. The removed fuel elements still give off heat. Because of this, they are first placed into water-filled spent fuel pools filled at the facility, before they can be processed or put into interim storage. After five years, the fuel elements are placed into hermetically sealed, high tensile containers for interim storage. We envisage a maximum storage time of 40 years for each container.

Interim storage facilities serve the same purpose as regular warehouses; however, they are built to be especially hard-wearing. Neither an elaborate cooling system nor a complicated monitoring system is required for the storage of fuel element containers. Natural ventilation provides for low-maintenance continuous removal of the heat given off by the containers.

Permanent Disposal

The generations that benefit from the advantages of secure supplies of competitive and CO2-free electricity generation from nuclear power, and of nuclear medicine, must also bear the responsibility for waste disposal. Safe interim storage is only a temporary solution. The disposal issue must not be postponed to future generations.

The peaceful use of nuclear energy produces low- and intermediate-level radioactive waste, in research and medicine, as well as in the operation of nuclear power plants; the last also produces high-level waste. In Germany, about 90 percent of the accumulated nuclear waste is of low- and intermediate-level radioactivity (ca. 270,000 cubic meters) and about 10 percent is high-level (ca. 24,000 cubic meters). Currently, the radioactive wastes are in interim storage facilities. They have to then be permanently disposed of in deep geological formations.

It is the Federal Government's responsibility to provide suitable, which means safe, final repository sites. Within the Federal Government, responsibility rests with the Federal Ministry for the Environment, Nature Conservation, and Nuclear Safety and its subordinate top federal agency, the Federal Office for Radiation Protection (BfS). The German Society for Construction and Operation of Waste Repositories mbH serves this function in practice. Ultimately, the authorities in the states where a repository is located are responsible for its approval. The costs of waste disposal are borne by the producer of the waste: that means essentially the energy supply companies, but also the public sector.

Technically, the issue of final storage has already been solved. As is standard procedure throughout the world, Germany relies on technically safe, beneficial, separated repositories of different types of waste. By comparison with other nations, Germany has a far-advanced concept of waste management. This well-established two-facility concept for final waste disposal consists of the locations at the Konrad Shaft and the salt dome exploratory mine in Gorleben.

Konrad Shaft - An Approved Permanent Repository for Low- and Intermediate-Level Radioactive Waste

Konrad Shaft, approved for low- and intermediate-level radioactive waste, is a former iron ore mine in Salzgitter, which is intended to provide for disposal of all low- and intermediate-level wastes accumulated in Germany. Two-thirds of that is to come from the energy companies and one-third from the public sector: for example, wastes from research laboratories and clinics.

The final repository was approved in 2002 by the Lower Saxony Environment Ministry. In April 2007, the Federal Administrative Court upheld the decision. In early 2008, the State Office for Mining, Energy, and Geology of Lower Saxony accepted the main operating plan for construction of the repository in early 2008. Work also began on upgrading the Konrad Shaft. The BfS plans to commission the disposal facility in the middle of this decade.

The Gorleben Salt Dome - Potentially Suitable Repository for Highly Radioactive Waste

Germany has chosen rock salt as a final disposal medium for high-level radioactive waste. Rock salt is more suitable for this than almost any other type of rock. Indeed, Germany is internationally envied for its rock salt deposits.

The salt dome in Lower Saxony's Gorleben was selected, after a thorough scientific investigation, from over 140 salt domes. The decision was made jointly between the Federal Government and the state of Lower Saxony. The municipalities and the local public also participated. Gorleben could absorb all the highly radioactive waste accumulated in Germany.

According to the current extent of geological exploration, the salt dome is suitable as a final repository for highly radioactive waste. If things go as expected, further exploration and a subsequent approval process will also confirm the suitability of the site, and a final repository could go into operation at the Gorleben salt dome at the end of the next decade.


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Decommissioning of the EPC VENTURE nuclear power plants

Under the amended Atomic Energy Act which came into force in July 2011, eight of the German nuclear power plants were shut down immediately and the remaining lifetimes of the other nine plants were significantly shortened.

Our nuclear power plants Isar 1 and Unterweser were disconnected from the grid in March 2011, since when they have been in shutdown operation.

EPC VENTURE plans – subject to the outcome of the constitutional proceedings against the 13th Amendment to the Atomic Energy Act – to decommission and dismantle the two nuclear power plants Unterweser and Isar 1. EPC VENTURE applied for the appropriate permits for the two plants in May 2012. Further information on the conditions for the decommissioning of a nuclear power plant and the technologies used is available via the menu on the left. In addition, the pages which can be accessed via this menu give you an idea of the Isar 1 decommissioning project.

Just as in the further operation of our remaining nuclear power plants, safety is the top priority in decommissioning and dismantling.

Legal framework

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In Germany, the construction, operation and decommissioning of nuclear power plants are governed by the Atomic Energy Act.

As in the case of construction and operation, a permit is required for the decommissioning of a nuclear power plant. Decommissioning is subject to a strict official approval procedure with the participation of the public in order to protect the public and the environment against radiation. An environmental impact assessment is carried out as part of the approval procedure.

Approval procedure

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Decommissioning approaches

The German Atomic Energy Act provides for two approaches to decommissioning.

Demolition following safe enclosure

This variant provides for the demolition of the plant following the construction of a safe enclosure. With this decommissioning strategy, a nuclear facility is transferred to a condition with low maintenance requirements for a period of about 30 years, after which it is finally demolished.

Direct demolition

With this variant, the plant is demolished immediately. The dismantling of all systems and equipment starts directly after the plant has been disconnected from the network. Normally, demolition is completed in several phases. The number of phases depends on the application submitted by the operator.

Decommissioning variants

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Generator and reactor buildings

Cutting work is mainly carried out using tried and tested tools of the types normally used in industrial projects. These include oxyacetylene cutters, electric saws, hydraulic wrenches and shears, angle grinders and manual tools such as saws and bolt cutters. Extraction systems with filters prevent dust from escaping into the working atmosphere while cutting work is in process. For various tasks, areas with separate ventilation and complete enclosure are established. Following dismantling work on site, cutting work, decontamination and waste treatment take place in the turbine hall of the generator building.

Reactor components

In future, special equipment will be used for some steps in this work. For example, reactor components may be dismantled under water. This has two advantages: water provides a shield against radiation at the same time as preventing the emission of dust into the atmosphere.

Water jet cutting with abrasive

A nozzle delivers a high-pressure water jet with an abrasive such as corundum or sand. The extremely fine cutting jet can cut through steel with a thickness of several centimeters without any problems.

Underwater shears

Activated metal components such as control rods, instrument assemblies or fuel assembly channels are cut underwater. The material which has been cut is packed in containers made from materials such as cast iron, which are also used for shipment.

Building components

At an advanced stage of decommissioning, when the reactor pressure vessel has already been demolished, large reinforced concrete structures in the reactor building need to be demolished. Saws are mainly used for this purpose.

Rope saw

The rope saw consists of a steel rope with a thickness of 10 mm coated with industrial diamonds. This saw is inserted through holes which have been drilled and cuts the concrete in a continuous loop.

Sword saw

Concrete about 2 m thick can be cut using a sword saw. It is not necessary to drill any holes before using this type of saw.

Demolition material

Most of the material is already sorted during the demolition process so that it can be effectively recycled. For example, reinforced concrete components are often shredded on site. In this process, the steel reinforcement is separated from the concrete. The rubble can then be used for road building while the steel scrap is used in steel production.

Cleaner than clean

Most of the material produced by the dismantling of the control building is only subject to surface contamination (radioactive contamination).

In order to facilitate decontamination, a special non-porous coating was already applied to the surfaces of various components during construction. These components can normally already be decontaminated by thorough washing or scrubbing. Contamination that has penetrated the material through cracks and pores is removed mechanically or chemically using high-pressure water jets, ultrasonic cleaning and jets with steel granulate.

Waste reduction

As a result of thorough decontamination, only a very small proportion of the material produced by demolition needs to be disposed of as radioactive waste. In order to further minimize the storage volume needed for radioactive waste, volume reduction technologies such as high-pressure compaction are used.

About 98% of the total mass can be released and recycled. Only about 2% needs to be disposed of as radioactive waste. This is conditioned during dismantling and packed so that the containers can be handled and stored safely.

The Isar 1 project


Direct demolition in two phases

EPC VENTURE intends to apply the direct demolition procedure to Isar 1. It is assumed that not all the fuel assemblies exposed to radiation will have been removed from the plant at the beginning of demolition work.

It is currently planned to complete demolition in two phases. Separate permit applications under the Atomic Energy Act have been made for each of the phases. When these permits have been issued, the work in the two phases may also be carried out in parallel, provided that the various operations do not have an adverse impact on each other and that the work is carried out in accordance with the protection objectives as well as radiation protection, health and safety, and fire protection requirements.

Basic principles
  • The top priority in the planning and implementation of the decommissioning and demolition project is the protection of employees, the public and the environment.
  • Any impact of the decommissioning and demolition work on fuel assemblies in the fuel pool will be prevented until the disposal of the fuel assemblies has been completed.
  • The quantity of radioactive waste produced (see “demolition material”) will be minimized.
Procedure

When demolition work starts, the removal of fuel elements exposed to radiation and individual faulty fuel rods will not have been completed. At this stage in the project, demolition work will be limited to systems, components and areas not linked in any way with the safety of the systems used for the cooling and storage of fuel assemblies and the fuel pool (freedom from impact).

For the demolition of the Isar 1 nuclear power plant, infrastructure for the processing of residual materials and waste will be established within the existing controlled area of Isar 1. This infrastructure will be designated as a residual material processing centre and is also to be used for the later decommissioning of the Isar 2 plant. The main components of this infrastructure will be installed in the generator building.

Working areas will be equipped and established in accordance with the applicable health and safety, fire protection and radiation protection requirements.

Procedure – demolition phase 1

In this phase, demolition work will focus on
  • Systems and plant components with no safety significance for this plant status,
  • Reactor pressure vessel internals and
  • Containment internals.
The systems to be dismantled inside the containment include piping systems, such as feedwater piping, fresh steam piping, shutdown cooling piping, safety and pressure relief valves with associated piping, etc.

In addition, work platforms and systems for the later demolition of the containment will be installed in the containment.

Procedure – demolition phase 2

The demolition work of phase 1 will be continued. At the same time, phase 2 work will start. This will include
  • The demolition of the reactor pressure vessel,
  • Further clearance and demolition of the containment,
  • The demolition of the reactor shield, and
  • The radiation inspection of building structures and areas that are not to be used for the decommissioning of Isar 2.
  • Buildings and building areas that have been inspected and released (i.e., the controlled area consisting of the reactor building, turbine building and decontamination building) will be blocked off, sealed (if appropriate) and secured to prevent any risk of re-contamination.
Demolition of buildings

The conventional demolition of buildings which have been released in accordance with the Atomic Energy Act is outside the scope of the atomic energy law permits for phase 1 and phase 2 of the Isar 1 decommissioning project.

Disposal

Most of the material produced during demolition work in the controlled area of Isar 1 will neither be activated nor radioactively contaminated. This material will mainly consist of metal scrap and rubble.

Residual radioactive materials from the dismantling of the power plant will consist solely of waste with negligible heat development (low-level to medium-level materials). These materials will be identified prior to dismantling and disposal objectives will be defined. These objectives include unrestricted release (i.e. the parts can be reused or recycled without any restrictions), release for recycling or disposal (transfer to landfills), supervised recycling in the atomic energy industry, direct reuse within the scope of another atomic energy permit and storage in a final storage facility for low-level and medium-level radioactive waste

The various material groups will be collected separately. If dismantled plant components need to be disposed of as radioactive waste for radiological reasons, they will be conditioned in accordance with the approved acceptance conditions of the Konrad final storage facility. Waste containers will be stored at an intermediate storage site (e.g. the Mitterteich intermediate storage site) before they are transferred to the Konrad final storage site.

Material which is neither activated nor radioactively contaminated may be used or recycled immediately in other sectors. Most metal components will be returned to the material cycle as scrap. Concrete waste from the demolition of buildings may be used in the construction industry.

Estimates of demolition volumes, Isar1

The mass of materials to be disposed of was estimated on the basis of previous experience with the decommissioning of nuclear facilities..

The total mass of waste from the controlled area (reactor building, generator building plus internals, decontamination building) will be about 224,000 t.
  • Of this total, 200,000 t represent the mass of buildings which can be released. The demolition of buildings is not subject to the atomic energy permits for phases 1 and 2 and will be completed conventionally.
  • A further mass of 20,600 t may be released in accordance with Section 29, Radiation Protection Ordinance or re-used in the atomic energy field.
  • There will be about 3400 t of radioactive waste. This waste will be prepared for final storage at Schacht KONRAD.
Radiation protection
  • The protection of the public, employees and the environment will be the top priority in the planning and implementation of decommissioning.
  • Approved discharges from the nuclear power plant will be continuously monitored and supervised by the competent authority. In addition, the surroundings of the nuclear power plant will be continuously monitored for radioactive materials.
  • The radiation exposure of individual person as a result of discharges from nuclear power plants is so low that it cannot be measured despite the use of the best measurement equipment available. It was therefore estimated on the basis of conservative assumptions.
  • For the remaining operation and decommissioning of the Isar 1 nuclear power plant, radiation exposure was calculated in accordance with the General Administrative Regulation issued under the Radiation Protection Ordinance.
  • Even if full use is made of all the discharge limits applied for during decommissioning and demolition, the radiation load in the surrounding area will still be significantly below the statutory limits.
  • As in power generation operation, the actual discharges will be considerably below the statutory limits and the effective radiation burden on the surroundings of the plant will only reach a few percent of the statutory limits.
Safety at all times

Protective measures will be taken during the demolition and remaining operation of the Isar 1 nuclear power plant to ensure that the maximum radiation exposure in the event of an incident laid down in the Radiation Protection Ordinance is not exceeded in the surroundings of the plant.

Extensive precautions have been taken to avoid any incidents and to limit the impact of any incidents. These precautions include regular inspections of all the equipment, protection systems and stand-by protection systems required, a barrier system for the retention of radioactive materials and shielding against radioactivity.

In addition, incidents which could theoretically occur as a result of internal or external impacts have been considered on the basis of conservative assumptions. The radiological consequences of such incidents in the surroundings of the plant have been assessed.

Even in the event of the possible incidents considered in connection with the remaining operation and decommissioning of Isar 1, expected radiation exposure in the vicinity of the plant will still be far below the statutory limits.

 

 

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