Management of RAW from NPP


The Specialized Division Radioactive Waste – Kozloduy (SDRAW Kozloduy) operates within Kozloduy NPP. The division collects, sorts, transports, processes, and stores RAW generated from the operation and maintenance of the power plant units.

According to proven statements by the World Nuclear Association, nuclear energy is the only industrial branch fully responsible for all the waste generated during operation. In Bulgaria, this mission is performed by State Enterprise Radioactive Waste.

In the early 90’s of the 20th century, in connection with the commissioning of the two 1000 MW power units of Kozloduy NPP, there arose a necessity for a long-term and reliable solution concerning the management of high- and intermediate-level radioactive waste generated by the nuclear power plant.

In 1997-2000, intensive construction and pre-commissioning activities were performed within the future division, which at that point was functioning as a RAW and SNF Management Unit within the Kozloduy NPP.

On April 29, 2005, SE RAW was granted a License E-series, registration No. 01740 for operation of nuclear installation for radioactive waste management through Specialized Division RAW – Kozloduy. The License was renewed in 2008 due to expiration of the validity period. The new document is valid for the next seven years, until 2015.

As a result of the NPP operation and maintenance, different types of waste are generated, which are categorized into different streams. In general, the low- and intermediate-level RAW could be separated into two main groups – liquid and solid waste.

The high-level RAW of category 3, in accordance with Art. 5 of the Regulation for Safe Management of RAW, shall not be collected in SDRAW – Kozloduy for processing, but shall be stored in the repositories of Kozloduy NPP.

The spent nuclear fuel, according to the existing Bulgarian legislation, is not defined as a radioactive waste. Its management is the subject of agreements between Bulgaria and Russia, where the spent fuel is returned over certain periods of time.

SE RAW attends to the low- and intermediate-level radioactive waste of category 2A, generated in Kozloduy NPP.

The solid radioactive waste is generated as a result of the maintenance and repairs of the NPP facilities. They are parts of dismantled equipment, reinforcement, filters, tools, special clothing for work in the controlled area, construction waste, etc.

The liquid radioactive waste is in the form of water solutions, suspensions, concentrates, oils. A considerable amount of radioactive waste is expected to be generated also during the process of gradual decommissioning of Kozloduy NPP units.

The Specialized Division Radioactive Waste – Kozloduy works on complex programs that cover all activities concerning the management of RAW generated as a result of the operationof the plant, and of “historic” RAW as well.

The RAW management covers the entire technological cycle – from their generation, through preliminary treatment, processing, transportation, to their turning into appropriate condition for temporary storage and subsequent disposal.

The activities of SDRAW Kozloduy are carried out through three main installations:

-          RAW processing shop;

-          Storage facility for conditioned RAW;

-          Lime storage facility.

The RAW processing shop includes three main processing lines:

-          Processing line for solid RAW;

-          Processing line for liquid RAW;

-          Installation for decontamination of metal RAW.

The processing line for solid radioactive waste has a capacity of around 1300 m3 per year.

The processing line for liquid radioactive waste has a capacity of 450 m3 per year.

The installation for decontamination of metal RAW (IDMRAW) is of modular type and has a capacity of 25 tons per year.

Upon processing the waste is packed in reinforced concrete containers (RCC) whose treatment depends on the type of waste to be placed in them. Within one working shift the division processes around 10 m3 of solid and 5 m3 of liquid radioactive waste. A basic principle in the waste processing is the aim to reduce the waste volume.

The specialized process control is performed in a modern laboratory complex.

The second installation of SDRAW Kozloduy is the storage facility for conditioned RAW (SFCRAW), which has a capacity of 1920 reinforced concrete containers and is designed for temporary storage. SFCRAW is a modern overground facility. All operations within it, including storage of packages with conditioned radioactive waste, are performed through computer software, remotely, from a control panel provided with video equipment.

From environmental perspective, three engineering barriers are provided to prevent the release of radioisotopes in the environment. The first barrier consists in the result of the overall treatment, which is a final cemented product. As a second step the product is sealed in a reinforced concrete container cast with a unique identification number, and the product is eventually placed in specialized a storage facility.

Thanks to the operation of the Specialized Division RAW – Kozloduy, the issue with the low- and intermediate-level RAW, which have been collected for over 35 years of  operation of the nuke, since the commissioning of Unit 1, is gradually being solved permanently. Over the years, they were stored in an unprocessed state, according to their initial design, in isolated areas belonging to the individual NPP units, called auxiliary buildings, and the lowest level radioactive waste – on an outer site. Nowadays, the so called “historic waste” is being gradually retrieved, transported, processed and minimized within the division, and then  placed in safe packages.

The experience gained by the specialists during the years of facility operation ensures successful implementation, and even overfulfilment of the annual production schedules. This fact is indicative of the high efficiency of the specialized division at such a professionally challenging moment as the process of decommissioning of nuclear facilities, which will require extremely intensive work.