ABSTRACT
The WWR-M is a light-water-cooled and moderated heterogonous research reactor with a thermal output of 10 MW. The reactor has been in operation for >50 y and has had an excellent safety record. A non-hermeticity of the inlet line of the primary cooling circuit (PCC) was found, and the only reasonable technical solution was the complete replacement of the PCC inlet and outlet pipe lines. Such a replacement was a challenging technical task due to the necessity to handle large size components with complex geometries under conditions of high-level radiation fields, and therefore, it required detailed planning aiming to reduce staff exposure. This paper describes the dismantling and removal of the PCC components focusing on radiation protection issues.
Subject(s)
Decontamination/instrumentation , Nuclear Reactors/instrumentation , Occupational Exposure/analysis , Radiation Monitoring , Radiation Protection , Humans , Radiation DosageABSTRACT
Accumulation of a wide range of metals by the "mixed microbe communities" (MMC) from Kyiv sewage treated in the air tank has been studied. MMC is a mixture of one or more synthrophical associations, such as microorganisms of fermented metantank deposit and cow manure. The exposure being 48 h and weight ratio of the phases MMC : sewage being 1:50, MMC lower the concentration of Ca, Fe, Zn, Cc, Au in sewage by 1 order; Cr, Mn, Co, Ag, Cd, Ba, Sm, Hf, Th--by 2 orders; Sc, Sb, La--by 3 orders. MMC may be used efficiently for deep tertiary treatment of sewage for toxical heavy metals, for extraction of rare-earth and non-ferrous metals from superdiluted solutions and industrial sewage.
Subject(s)
Cities , Metals, Heavy/analysis , Refuse Disposal/methods , Sewage/chemistry , Sewage/microbiology , Bacteria , Metals, Heavy/chemistry , UkraineABSTRACT
Accumulation of a wide range of radionuclides by the microbial sorbent has been studied. The microbial sorbent represents granules stable in water solutions for a long period of time. The sorbent includes: concentrated biomass of metabolically active microorganisms, sources of carbon and energy, phosphorus, nitrogen, etc. Availability of nutrition sources in the sorbent provides for metabolic activity of microorganisms immobilized in granules. Metabolic activity of the sorbent was characterized. Physico-chemical sorption and metabolic activity of microorganisms lead to the extraction of a wide spectrum of radionuclides (51Cr, 54Mn, 60Co, 90Sr, 134Cs, 137Cs, 140La, 144Ce, 226Ra, 83Rb) from liquid radioactive waste. The extraction factor for some radionuclides was 10(5)-10(6). The waste sorbent may be utilized. Absence of water phase in the ash concentrate permits the radionuclides to be buried in borosilicate or volcanic glass (accepted time of existence 10(5)-10(7) years). The sorbent may be used to create new biotechnologies of radionuclide accumulation from water solutions.
