Stone, the previous period is often associated with "radioactivity, radiation", so many people who want to use stone because of "stone radioactivity" are discouraged, people who have used stone are more like needles, often readers call to ask where to detect What is the radioactivity of the stone? What if the home is paved with stone? The anxious meaning is beyond words. What is the radioactivity of stone? Can you use it at home? Recently, the reporter visited Associate Professor Hou Shengli of the Department of Applied Geophysics of China University of Geosciences (Beijing).
â– Any decorative materials have natural radioactivity, which is only harmful if it exceeds the standard.
Professor Hou said: Any substance in nature contains natural radioactive elements, but the content of radioactive elements in different substances is different. Radioactive elements are found in the soil, water and even the air in our surroundings. Non-stone building materials such as cement, steel, bricks, whole-body bricks and the like contain radioactive elements. Take the whole body brick, it is made of clay and other materials. The clay is formed by the weathering of the rock. The clay and the stone are naturally formed. If the radioactive element in the clay is relatively high, then the whole brick is fired. The content of radioactive elements is also correspondingly high, so it is considered that only stone materials are radioactive, and other materials do not contain radioactivity. The Ministry of Health also issued the “Standards for the Protection of Building Materialsâ€, which regulates the activity of natural radioactive elements in building materials to ensure safe use.
â– 80% of the stone can be used indoors with confidence, and the stone with very low radioactivity can also shield the radiation of other materials.
When the reporter asked which kind of stone is suitable for use at home, how to choose, Professor Hou said: As early as 1993, the National Building Materials Bureau issued the "Classification Control Standard for Radiation Protection of Natural Stone Products", which was based on the level of radioactivity of natural stone. Classification, the natural stone is divided into three categories A, B, C, A products can be used in any occasion, B products can be used in all interior and exterior finishes and industrial facilities except for indoor interiors Class C stone can only be used as a building exterior. From our test analysis of nearly 200 samples, 80% of the stone samples belong to Class A stone that can be used in any occasion. Some of the stone materials have extremely low radioactivity content, even lower than the radioactive content of ordinary cement floors and bricks. The use of such stone materials in the room can play a shielding role, reduce the total indoor radiation, and have an environmental protection effect.
Because some people lack the knowledge of radioactivity, they have formed some one-sided understanding. For example, some people think that light stone is less radioactive than dark stone. In fact, this is not absolute. Many dark stones (such as red) have no radioactivity. Higher than the standard specified in Class A, it is lower than some light-colored stones, which can be proved in the tests we have done.
â– How to detect whether indoor radioactivity exceeds the standard
How to detect whether indoor materials exceed the standard is a concern of many people. According to Prof. Hou, the conventional test methods are mainly indoor gamma spectroscopy and radiochemical analysis. The samples to be tested are ground and sealed, and the analysis period is about 20 days. The analysis cost of the cycle is also relatively high. In response to this situation, with the support of the National Stone Quality Monitoring Center, the Department of Applied Geophysics of China University of Geosciences (Beijing) and the China Stone Industry Association have jointly developed China's first stone radioactivity detector and its related measurement method technology, and It passed the expert appraisal of the National Building Materials Bureau and obtained the certificate issued by the Beijing Municipal Bureau of Quality and Technical Supervision. The reporter saw this instrument in the geophysical department of the University of Geosciences. The instrument equipped with the probe is like a flashlight, and a small display tester is taken. This portable instrument can be taken to the field for testing without destroying the finished product. Tested on the finished product, the test range is up to 50 × 50 cm, and the detection time is short, generally takes about 10 minutes to measure. Finally, Professor Hou said that the home environment is a whole. As long as the radioactive indicators in this large environment reach the standard, it will not affect the human body. Do not blindly dismantle the radioactive standards of a certain material, which is unnecessary. Waste and trouble.
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