Бидний тухай
Багш ажилтан
1. Introduction Curd is one of the Mongolian traditional dairy products, nutritious and useful in many ways for the human body. Mongolians produce curd at the household level, usually by manually processing milk. In recent years, it has been mass-produced and sold in the domestic market. In this study, we select a type of curd – khorkhoi aaruul, commercially available, irradiated them with 3 different doses of X-ray radiation, and compared their microbial and physicochemical qualities with control samples’ in order to investigate the possibility of reducing the total number of bacteria, extending the shelf life, and complying with international hygiene standards. 2. Methods We irradiated the samples using an RS1800 Q4 biological irradiator (figure 1) [1]. Irradiation doses were 1 kGy, 3 kGy, and 5 kGy. We measured the total number of bacteria, the total number of molds in the irradiated and control samples. Also, in order to study the physicochemical changes in curd after irradiating with the ionizing radiation, the content of proteins, fats, minerals, vitamin C, and changes in color, smell, and taste were determined. 3. Results and Discussion When curd samples were irradiated with X-rays, the total number of bacteria was significantly reduced. The total number of bacteria in the control sample was 4.20*106 cfu when grown in plate count agar non-selective medium, while the total number of bacteria in the sample irradiated with 1 kGy decreased to 3.20*106 cfu; 1.20*106 cfu after irradiating with a dose of 3 kGy, and 2.00*105 cfu after irradiating with a dose of 5 kGy, respectively. However, the intestinal pathogenic bacteria and molds were not detected when cultured on selective media Endo agar and Sabouraud’s dextrose agar. Table 1. Analyzed chemical composition of the control and irradiated samples. Irradiation dose Item Control 1 kGy 3 kGy 5 kGy Protein (%) 33.71 24.01 21.51 18.78 Fat (%) 27.72 24.03 22.31 19.62 Vitamin C (mg in 100 g) 2.28 2.11 2.06 2.14 X-ray irradiation did not occur any changes in the mineral content and chemical groups in the curd samples. It was observed that the storage time was extended, and among the 4 types of samples, the control sample started to mold first. There were no changes in sensory tests such as color, taste and smell. 4. Conclusion When the samples were irradiated with a dose of 3 kGy, the total number of bacteria decreased by 3-4 times. At 5 kGy irradiation, the total number of bacteria was greatly reduced, but other parameters, such as protein and fat content, were reduced. However, the total number of bacteria did not decrease sufficiently when irradiated with a dose of 1 kGy. Therefore, it was considered that it is possible to extend the shelf life of the selected brand of curd without losing its nutritional quality by irradiating them with 3 kGy dose
Энэхүү ажлаар мал эмнэлгийн хүрээлэнд эрдэм шинжилгээ, судалгааны зориулалтаар ашиглаж буй RS-1800 рентген шарах төхөөрөмжийндээжинд өгч буй шингээгдсэн тунгийн орон зайн түгэлтийгтодорхойлов. Үүнээсөмнө 2019 онд анх төхөөрөмжийг суурилуулж, үйлдвэрлэгчээс өгсөнтунгийн чадлын утгыг ашиглан судалгаа шинжилгээний ажлыг гүйцэтгэж байв. Манай улсад судалгааны зорилгоор ашиглаж буй шарлагын төхөөрөмж өөр байдаггүй. Тус шарлагын төхөөрөмжийнтунгийн чадлыг тодорхойлж, баталгаажуулах нь энэхүү багажийг ашиглан хийж байгаа судалгааныажлуудынүр дүнг баталгаажуулах, тунгийн утгаас хамааруулан тооцоололхийх зэрэгт чухалач холбогдолтой. Судалгааны ажлын дүнд шарлагын төхөөрөмжийн камердоторхдээжинд өгөхшарлагынтунг дээжийн байрлалаас хамааруулж тодорхойлсон.Мал эмнэлгийн хүрээлэндсуурилуулсан рентген шарах төхөөрөмж нь хар тугалган хамгаалалттай(self-sheilded),туршилтсудалгааныдээж шарахад зориулан бүтээсэнионжуулах цацрагийн үүсгүүр юм.Рентген хоолойн хувьд160кэВ хүртэл энергитэй полихроматик рентген цацрагийг гаргадаг. Шарлагын хэсэгбуюу камер ньрентген хоолойноос 22.2 см хүртэл зайнд орших гурван түвшинд шарлага явуулдаг.
Most of the solid wastes from Ulaanbaatar city during the cold season are ashes from the partial combustion of coal. Burial of the ashes with other solid wastes has affected radioactive isotope levels in the soil. We investigated soil radionuclides 226 Ra, 232 Th, 40 K, and 137 Cs describing soil samples collected from the Naran Enger landfill using gamma-ray spectrometry. The natural radionuclide contents soil were highest underneath the waste buried zone and lowest around the “Ger” areas and the initial reference location. The levels of some isotopes were intense underneath the buried zone ( 40 K) isotope content was two times higher) and some of them ( 137 Cs) were lower, compared to the world average. In our result has shown the Ra eq has ranged between the 69 - 183 Bq kg -1 , and Ra eq of ash was 338.3 Bq kg - 1 , respectively. Then, external and internal hazard indexes were 0.2 and 0.5 respectively. From the Ra eq , H in , H ex , D out , and D in values, we calculated life time cancer risk and we found out that cancer risk between 0.8-1.58*10 -3 . Current values of radium equivalent and hazard indices have found to be within the recommended limits.
We have studied prolonged storage and total bacterial count reduction in Mongolian traditional dairy product – small curd (Khorkhoi Aaruul) due to effects of X-ray irradiation. Different amounts of absorbed dose were used such as 1 kGy, 3 kGy and 5 kGy, and compared the effects of these doses with negative control group. Before and after the irradiation, we measured changes of total protein, lipid, vitamin C and changes of chemical composition, and physical state of whole samples. There were no significant changes occurred in both of chemical and physical states but the most beneficial effect was the total number of bacterial cell count in sample. After X-ray irradiation of 1 kGy of absorbed dose, the total bacterial counts were reduced from 4.1*106 control group to 3*106, and in case of 3 kGy total counts was reduced to 1*106, and for the 5 kGy the bacterial counts were significantly reduced to 2*105 colony forming units. Same trend was observed for the total mold counts. Depending our results, we suggest that ionization irradiation has beneficial effects to prolonging storage period and reducing microbial contamination in Mongolian traditional food –Aaruul. In addition, our results confirmed that ionization radiation does not have significant adverse effects on nutritional value, flavor, appearance and texture of Aaruul.
Энэхүү ажлаар бага чадлын түлшээ үржүүлэн шатаадаг реакторын дизайны нейтроникийн судалгааг Монте Карло аргад сууриласан Япон Улсын Атомын Энергийн Агентлагаас хөгжүүлсэн MVP-GMVP-II комьютерийн кодыг ашиглан гүйцэтгэсэн. Бага чадлын түлшээ үржүүлдэг реакторын хувьд шаталтыг эхлүүлэх нь чухал асуудал байдаг бөгөөд энэ ажлаар баяжуулсан ураныг голомтод бүсэд хуваан ачааллана шаталтын тооцоог гүйцэтгэсэн. Тооцооллын үр дүнгээс харахад бүс ачаалалтай голомт анхны ачаалласан түлшээр 70-аас дээш жил ажил байгаа нь энэхүү ачаалал үр дүнтэй байсныг илтгэж байна.
Энэхүү өгүүлэлд манай улсад байгалийн хийн нөөц тогтоогдоогүй, эрчим хүчний анхдагч эх үүсвэрийн ихэнх нь хүрэн нүүрс, уран тул цөмийн эрчим хүчний өндөр температурын реактор ба өндөр температурын цахилгаан химийн төхөөрөмжийг хослон ашигласнаар цахилгааны ачааллыг тохируулах, ус, нүүрснээс устөрөгч үйлдвэрлэж экологийн үнэмлэхүй цэвэр цөм-устөрөгчийн эрчим хүчний үзэл баримтлалыг ойрын ирээдүйд хөгжүүлэх асуудлыг дэвшүүлж тавив.
In Mongolia, energy demand is increasing rapidly and installed capacity cannot keep up the demand due to a weak condition of both electricity access and grid structure. According to a survey, primary electrici-ty demand by 2025 would be higher in the central region and tend to increase in other regions. Full cov-erage of the country by grid extension is difficult from technical as well as economic perspective be-cause of high investment costs and high electrical loss over long distance, and low demand in the re-mote regions. Therefore, small power systems are suitable in remote regions and typical large size pow-er systems are not a very good option. However, a small fast reactor system may be suitable, having unique characters, to reduce nuclear waste and effective use of nuclear fuel. In this study, preliminary design study on a small breed and burn type fast reactor was carried out using continuous energy Monte Carlo code MVP/GMVP II with the JENDL-3.3 data library. In the concept of breed and burn, igniting a burning wave is an important concern. This study concerns the igniting burning wave with enriched ura-nium for initiating the conversion process. As seen from the result, the proposed small reactor could operate more than seventy years under breed and burn mode.
Mongolia intends to build its first nuclear research reactor with main purpose of producing radioisotopes and other useful applications. However, technical specifications of research reactor have not decided and reached consensus among the scholars and decision makers. Thus, this paper presents results of preliminary neutronic analysis on three different cores at three different power level.
Энэ ажилд Финландын Техникийн Судалгааны төвийн хөгжүүлсэн SERPENT2.1.30 Монте карло кодыг ашиглан 20%-ийн баяжуулалттай ураны исэл (UO2) бүхий TRISO түлш, 100 МВт-ийн чадалтай, 927оС температурт ажиллах төвдөө ойлгогчтой, өндөр температурын хийн реакторын голомтын дизайныг хийж нейтроник тооцооллыг гүйцэтгэв. Тооцоололдоо ENDF/B-VI.8 цөмийн урвалын өгөгдлийн санг ашиглав. Ийм голомтын тооцоог өмнө нь тасралтгүй энергийн мужид болох шилжилтийг Монте Карло аргаар тооцоолдог MVP/GMVP 2.0 комьпютерийн кодыг ашиглан нейтроник тооцооллуудыг гүйцэтгэж анализ хийсэн. Ижил аргаар тооцоолол гүйцэтгэдэг кодууд ашиглан гарган авсан үр дүнгүүдийн харьцуулалт хийв.
Монгол улс анхны цөмийн судалгааны реакторыг эмнэлгийн зориулалттай цацраг идэвхт изотоп үйлдвэрлэх, шаардлагатай хүний нөөцөө бэлтгэх зориулалттай ашиглахаар төлөвлөж байна. Уг судалгааны реакторын техникийн үзүүлэлт ямар байх асуудал дээр эрдэмтэн судлаачид болон шийдвэр гаргагчид нэгдсэн шийдвэрт хүрээгүй байна. Эрдэмтдийн зүгээс чадлын хувьд дунд төвшний реактор манай улсад илүү тохиромжтой гэсэн өнцгөөс харж байгаа бол шийдвэр гаргагчдын хувьд реакторын үнэ ханш өндөр үнэтэй болно гэсэн байр суурьтай байдаг. Энэхүү судалгааны ажлаар реакторын техникийн үзүүлэлтийг харьцуулсан гурван өөр түлш бүхий, чадлын хувьд ялгаатай судалгааны реакторуудын дизайны судалгааг хийж, реакторын чадлаас хамаарч судалгааны реакторын хэрэглээ, ашиглалт хэрхэн өөрчлөгдөж болохыг харуулахыг зорьсон.
ABSTRACT Since 2014, the study on research reactor design suitable for Mongolia has been started at Nuclear Research Centre, National University of Mongolia. As seen from the result of these works, research reactors from Russia could highly be the Mongolian first nuclear reactor due the geographical issue and long lasting cooperation with Mongolian and Russian scholars. However, selecting the power level of the reactor have not reached a consensus among the decision-makers and scholars in Mongolia. From the side of the scholars, they recommend the mid-range of reactors in which can carry out research studies and other related activities like producing industrial and medical radioisotopes while the decision-makers consider that the reactor could be expensive and cannot afford. In order to reach a conclusion, detailed neutronic analysis on commercial fuel assemblies in Russia are needed to proof for the scholars that the medium power reactors could fulfil the applications to Mongolia.
In the present work, we have focused to design an annular and solid cylindrical prismatic, very high temperature reactor core (VHTR). The fundamental neutronic analyses using the continuous energy Monte Carlo code MVP2.0 and MVPBURN with the nuclear data library of JENDL-4.0 are carried out for the core with power of 100 MWth. In the study, it was used the advanced TRISO fuel with a solid layer of ZrC deposited over the kernel in which 235U was enriched by 20% of. The preliminary neutronic results are compared between the cores operating at temperature of 850oC with and without ZrC additional layer and it shows that the effective neutron multiplication factor in BOC and discharged burnup are increased, while a core lifetime is reduced due to existence of the ZrC layer. Therefore, neutronic feature of an annular prismatic VHTR core with ZrCcontaining TRISO fuel is improved for long term operation as higher fuel burnup in effect of inner reflector.
In the present work, we have designed annular cores of HTGRs in which the number of inner reflector blocks were one, seven and nineteen. The power of these reactors was the same as 100 MWt, as well as the number of fuel blocks in core and core size were the same. Then the fundamental neutronic analyses of those uniform cores for criticality and burn-up were performed using the continuous energy Monte Carlo code MVP2.0 and MVPBURN with the nuclear data library of JENDL-4.0. Next, calculations by introducing uniformly distributed burnable poison particles to suppress the excess reactivity and to flatten the reactivity swing and power peaking factor (PPF) during core operation were performed and obtained the optimal condition.
Энэхүү судалгааны хүрээнд бид Монгол төгрөгнд агуулагдаж байгаа нийт бактерийн тоог тодорхойлж улмаар ионжих цацрагаар үйлчлүүлэн бактерийн бохирдолыг бууруулах боломжийг судаллаа. Судалгаанд ашигласан мөнгийг дэлгүүр, эмийн сан, банк, цайны газар зэрэг нийт 7 газраас нийт 196 дэвсгэртийг 2019 оны 1-4 сарын хугацаанд санамсаргүйгээр цуглуулан авч ашигласан. Мөнгөн дэвсгэртийг эргэлтэд орсон хугацаагаар нь 2013 оноос өмнө ба дараа гэсэн 2 бүлэг болгон авч үзлээ. Эхний бүлэгт агуулагдах нийт бактерийн тоо 267.7±80.6 байсан бол хоёрдугаар бүлэг буюу харьцангуй шинэвтэр мөнгөн дэвсгэртүүдэд 77.6±47 байлаа. Хуучирсан мөнгөн дэвсгэртүүд нь сүүлд хэвлэгдэн эргэлтэд орсон төгрөгөөс 3.4 дахин их бактерийн бохирдолтой байна. Бактерийн тоог бууруулах зорилгоор рентген цацруулагчийг 200Gy, 400Gy хэмжээгээр, UV-A гэрлээр 22.5mJ/cm², 45mJ/cm², 90mJ/cm², 180mJ/cm², 360mJ/cm² хэмжээгээр тус тус үйлчлүүлж туршив. Туршилтын үр дүнд UV-A гэрлийн 180mJ/cm², 360mJ/cm² цацрагын тун бактерийн нийт тоог 93.5% ба 98% тус тус бууруулж байна.
The aim of the study is to determine total number of bacterial contamination on paper notes of Mongolian tugrug and reduce bacterial contamination using ionizing radiation. Total 196 paper notes (500₮) were randomly collected from 7 different places including store, grocery, pharmacy, bank, restaurant, coffee shop, fruit store between 2019 February to March. We divided paper notes 2 groups depending on aging, the first group of notes were released in circulation before 2013 and second group released after 2014. To isolate, determine and count total number of bacteria, mold and coliforms we used conventional microbiological techniques. Average number of total bacteria was 267.7±80.6 in first group and 77.6±47 was in second group. Aged paper notes were contaminated 3.4 times higher than newer notes but those results were statistically not significant (p≤0.05). The variation of bacterial contamination was unexpectedly high. Average number of coliform was 3 cfu and 18.75% of paper notes were contaminated with coliform bacteria. These results suggest that paper note is commonly contaminated with bacteria and this contamination may play in role of transmission of pathogenic organisms in community.
In this study, the preliminary design study on a small breed and burn type reactor was carried out. This study was performed in three stages, namely fuel pin, fuel assembly and core calculation. In the first two stages, neutronics calculations was performed in order to investigate fast reactor physics’ characteristics and preliminary burnup calculation was carried out in the last stage. The result of burnup calculation showed that the reactor could operate more than 10 years with initially loaded fuel, which is homogenous for whole core.
In this work, we have studied the lead-cooled fast reactor (LFR), one of the Gen-IV reactors for which a Russian type reactor with power of 300 MW(e)named BREST-OD-300 is a reference design. The purpose of this study is to investigate the lead-cooled fast reactor core design and to learn SERPENT-2 code as for basis to develop LFR core design for Mongolia. We have performed the preliminary neutronic analysis of BREST-OD-300 reactor core and three types of the fuel assembly using the continuous energy Monte Carlo SERPENT-2 code and cluster server at Nuclear Research Center, NUM. It is the firstly studied in NRC, NUM as for fast reactor core design and use of Serpent code. Fuel rods' diameters were different as 9.4 mm, 9.8 mm and 10.5 mm for the fuel assemblies in inner, intermediate and outer zones of the core, however, rod pitch was the same for these subassemblies in three zones.From the obtained results, the fuel assembly with the largest diameter gives higher effective neutron multiplication factor as an expectation, and the fuel assembly with the smallest diameter gives higher conversion ratios.
In the present work, we have focused to design an annular and solid cylindrical prismatic, very high temperature reactor (VHTR) core. The fundamental neutronic analyses using the continuous energy Monte Carlo code MVP2.0 and MVPBURN with the nuclear data library of JENDL-4.0 were carried out for the core with power of 100 MWth. In the study, it was used the advanced TRISO fuel with a solid layer of ZrC deposited over the kernel in which 235U was enriched by 20% of. Moreover, we aimed to investigate the possibilities of using alternative thorium-based fuel composition in this reactor. The calculation had been carried out to compare neutronic results of differences between standard uranium dioxide fuel and thorium based fuel.
We studied the capability of an annular, prismatic HTGR to remove decay heat passively. The purpose of the study was to obtain the design parameters relationship of the annular, prismatic HTGR with passive decay heat removal depending on power density profile and to compare them with those for solid cylinder one. The results showed that the safety feature of the annular reactor is improved a lot compared with that of cylinder one. The safety margin could be increased further by flattening the power density profile. Then fundamental neutronic analysis was performed for the annular reactor whose design parameters are obtained from the condition.
