Ingrowth Time Testing For Yttrium-90 In The Environmental Analysis Of Strontium-90 In Water

Measurement of environmental radioactivity is effort to protect the human being and environment to possibility of danger of radiation. The concerned radiation here is like X-ray, gamma ray and particles. Many research about radionuclide analysis method conducted to environmental samples have been done. Most methods used was pursuant to reference of research at around 1970’s, covering soil and sediment, water ( river, rain, sea, lake, underground water), dust particles, aerosol and air. Radionuclide contained in environmental samples what still conducted to the development and research are Strontium-90(Sr-90), Cesium-137, Cobalt-60, Iodium-Tritium, Radon, Radium, Americium, Uranium, Neptunium, Plutonium and Thorium. Each radionuclide have specification with behavior as α, β, or γ transmitters (Ngasifudin, 2007)

Research concerning radionuclide analyis method for Sr-90 is very attractive to be conducted, because radiostrontium is dangerous nuclide after radio-iodium among existing fissile product. Radionuclide of Sr-90 is pure β transmitter radionuclide with long half-life and found in many low activity radioactive waste inventories. The radionuclides were produced from an reactor work, radioactive disposal, fallout radioactive of nuclear test, and from nuclear contamination of installations that using the radionuclides. Sr-90 with half-life 28.1 years can contaminate ground water, because Sr-90 deposited either in continent and territorial water. Commonly, radionuclide of fissile product in underwater have low activity, so the measurement of specific activity must be done after concentrated or with chemical analysis.

Radionuclide analysis of Sr-90 in water will be conducted to separation of Sr-90 from matrix, then separating and counting of Y-90 daughter from Sr-90 after the equilibrium growth. Separation of Sr-90 from matrix material was conducted with chemical precipitation method. The obtained precipitate phase after solvent addition was separated from solution using filtration or centrifugation. Filtration or centrifugation was conducted swiftly and long time in order to homogenaising process of added solvent and precipitate can be separated gravimetrycally. The obtained precipitate then was cleaned or cleaned, to be dried and weighted, titration, and counted. In one method, red fuming HNO3 was added into solution to obtain yield 60~80% HNO3. At this condition [of]

Strontium (Sr) and Bromine (Br) of fissile product were precipitated as Sr and Br nitrate, while no for Calcium (Ca). At usage of 70~80% HNO3 in precipitation of Sr and of Br will be yielded 98~100% but contaminated by Ca. Contamination of Ca decrease if used 60% HNO3. Precipitation of StrontiumNitrate (Sr(NO3)2) will be used to sepatrate Sr-90 from Yttrium-90 (Y-90) daughters. Addition of Ba and Sr carrier will be conducted to precipitated Sr(NO3)2 with 80% HNO3 and Y-90 will remainedin solution. Sr(NO3)2 precipitated as SrCO3, and then stayed for one night or more for the ingrowth Sr-90 daughter that is Y-90. Ingrowth time of Y-90 depend on condition of Y-90 expected that is condition where equilibrium phase between Y-90 and Sr-90. Calculation specific activity of Sr-90 in ground water obtained from counting value of Y-90.