Filtration of radioactive element uranium - filter for nuclear power plants

January 16, 2019

The nuclear industry consumes a large number of air filters and has also completed a number of filter companies.

The famous filter companies that were initially established for the nuclear industry include: Sofiltra (France's largest filter company, 1989) In the year, it was merged by Camfil of Sweden), Vokes of the UK (the largest filter company in the UK), Camfil-Farr (Camfil of Sweden and Farr of the United States merged in 2000, both of which were partners of Cambridge), Shengda of China. Although the nuclear industry is no longer the most important market for the filter industry, historically, there are no such filter manufacturers without the nuclear industry.

Filters used in the nuclear industry are referred to as "nuclear filters."

High efficiency filter

In order to prevent radioactive dust from spilling into the atmosphere, nuclear power plant exhaust systems require a large number of high efficiency filters. The U.S. standard specifies that the efficiency of such a high efficiency filter is: 99.97% for a 0.3 mm DOP particle filtration efficiency. Most countries copy US standards, and some countries have their own test methods, but the filter performance is comparable to that measured by the US method.

In most countries, nuclear power plant efficiency filter using a separator in the form of a conventional filter, wherein the filter material is glass fiber filter paper, aluminum foil 0.038mm separator, the frame is steel or stainless steel, and an outer paper windward and leeward side of the block between the adhesive is a silicone, PVC, or other temperature resistant materials, the filter has a metal protective mesh. Many of the performance of nuclear grade filters are usually referred to as "excess performance" and those properties are considered for reliability in the event of an accident.

France is the originator of the non-separator filter. The French succeeded in replacing the traditional diaphragm filter with a non-separator filter in the nuclear power plant. The Korean nuclear power plant was imported from Korea and China, and the localization of the filter production was realized. Except for these three countries, no one dared to use a non-separator high-efficiency filter in key parts of the nuclear power plant.

The high-efficiency filters used in China's early nuclear reactors were similar to those in the United States. Later, China introduced nuclear power plants in France, Canada, and Russia. There are not many nuclear filters in China, and there are many styles. Those interested in China's nuclear-grade high-efficiency filter regulations can consult the national standard GB/T17939-1999 and send the products to the Zhengzhou Nuclear Fifth Hospital for testing and certification.

Activated carbon filter

Methyl iodide and iodine are fission products of radioactive element uranium , which are radioactive gases unique to the nuclear industry. In order to remove methyl iodide and iodine vapor from the air, nuclear power plants use a large number of activated carbon filters. Activated carbon materials for this type of application are subjected to special chemical impregnation to increase the adsorption capacity for methyl iodide and iodine. Habitually, the activated carbon material used in the nuclear industry is called "nuclear grade carbon", and the activated carbon filter is called "iodine adsorber".

Compared with ordinary activated carbon filters, the filter for nuclear power plants has a thick carbon layer, high adsorption efficiency, high temperature resistance and high seismic resistance.

Since the adsorption is an exothermic process, the excessive temperature may ignite the activated carbon, so the iodine adsorber has strict temperature resistance requirements. The concentration of methyl iodide and iodine in the nuclear fuel treatment plant is very high. At this time, the activated carbon can no longer be used, and other non-combustible porous adsorbent materials are used to manufacture the iodine adsorber.

Ventilation filter

According to the consumption, the largest amount of nuclear power plant is the filter for general ventilation. The reactor should be used, the auxiliary plant should be used, and the office and service area should be used.

Ventilation filters for nuclear power plants come in a variety of forms. They shouldn't have been so much more particular, but the specific specifications of the filters were determined at the beginning of construction, and the filter companies must supply them according to the original specifications. Unless otherwise unexpected, owners and suppliers do not dare to easily change raw materials, manufacturing processes, test methods and supply channels.
Safety first

Filters used in the nuclear industry are not much different in principle and structure from those used in other industries. Nuclear industry filters do not seek high-tech, do not engage in market economy, and do not price.

Safety first, reliable first.

Compared to filters used in other industries, filters used in the nuclear industry are subject to more testing and more certification. Those inspections and certifications are often done by specialized agencies that are controlled by the government and related to the nuclear industry. In addition, filter suppliers must have reliable qualifications and credibility, receive more or less government support, and have considerable performance and corresponding technical strength.

The certification body of China's nuclear filter is Zhengzhou Nuclear Fifth Hospital, but the Nuclear Five Institute, which has the power to kill the power, has set up a filter factory itself, so some competitors bypassed the nuclear five hospital and sold the filter to the nuclear power plant.

The limited capacity of the iron rice bowl

Due to the stability of the customer and the attractive price, the nuclear power plant has made many filter companies covet, but there are very few manufacturers that can really squeeze in.

If you count the total value of the filter, you will find that the filters used in nuclear power plants are not as much as people think. In developed countries, a reactor can only provide one or two jobs for filter companies, but this is an “iron rice bowl” that has been owned for many years. According to the current domestic production level, a reactor can still provide ten rice bowls for domestic filter companies. As the production level increases, the number of rice bowls will continue to decrease.

The construction period of nuclear power plants is seven years; due to the shortage of nuclear fuel, China's nuclear power industry is difficult to reach the level of the nuclear powers of the United States and France. But these do not prevent hundreds of people from vying for the rice bowl filter, at least not to hinder the filter salesman's imagination.

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Author:

Ms. Sunny Kong

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sunny.kong@sdfilters.com

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