• 제목/요약/키워드: Uranium enrichment facility

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북한 우라늄 농축시설로 인한 한반도에서의 공기중 우라늄 입자 농도 예측 (Estimation of Uranium Particle Concentration in the Korean Peninsula Caused by North Korea's Uranium Enrichment Facility)

  • 곽성우;강한별;신중기;이정현
    • Journal of Radiation Protection and Research
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    • 제39권3호
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    • pp.127-133
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    • 2014
  • 북한 우라늄 농축 시설은 국내외적으로 심각한 위협중 하나이다. 특히 우리나라 입장에서는 국가 안보에 관련된 사안이므로 항상 주시하고 대비를 하여야 한다. 북한 미신고 우라늄 농축시설 탐지 가능성을 평가하기 위해 시설로 부터 장 단거리에 따른 공기중 우라늄 농도를 예측하였다. 북한 농축시설에 대해 국제 사회에 알려진 정보와 다른 국가의 농축 시설 운영 데이터를 근거로 북한 시설로부터 공기중으로 누출되는 $UF_6$ 선원항(source terms)을 계산하였다. 계산된 선원항과 영변 주변 기상 자료를 바탕으로 장 단거리 대기 확산 모델 - Gaussian Plume and HYSPLIT Models -을 이용하여 북한 농축시설 주변과 멀리 떨어진 남한 지역에서의 공기중 우라늄 농도를 결정하였다. 최대 공기중 우라늄 농도와 위치는 기상 조건과 방출 높이에 따라 시설 바로 근처와 0.4 km 이내 이고, 농도 약 $1.0{\times}10^{-7}g{\cdot}m^{-3}$로 나타났다. 본 논문의 가정을 적용하였을 때, 수 십 ${\mu}g$ 정도의 우라늄 샘플을 채취할 수 있을 것으로 나타났다. 이 수십 ${\mu}g$ 우라늄 양은 현대 측정 장비로 어려움 없이 측정 가능한 양이다. 반면에 영변 농축시설에부터 수 백 km이상 떨어진 남한 지역의 농도는 $1.0{\times}10^{-13}{\sim}1.0{\times}10^{-15}g{\cdot}m^{-3}$이하로 자연 방사성 우라늄 농도보다 낮은 값이다. 따라서 본 논문에 의하면 북한 영변 농축시설 주변에서 공기포집에 의한 신고 및 미신고 핵활동 탐지는 가능하지만 장거리에서는 불가능할 것으로 예측된다.

MEASUREMENT OF $^{235}U$ ENRICHMENT USING THE SEMI-PEAK-RATIO TECHNIQUE WITH CdZnTe GAMMA-RAY DETECTOR

  • Ha, J.H.;Ko, W.I.;Lee, S.Y.;Song, D.Y.;Kim, H.D.;Yang, M.S.
    • Journal of Radiation Protection and Research
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    • 제26권3호
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    • pp.275-279
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    • 2001
  • In uranium enrichment plants and nuclear fuel fabrication facilities, exact measurement of fissile isotope enrichment of uranium is required for material accounting in international safeguards inspection as well as process quality control. The purpose of this study was to develop a simple measurement system which can portably be used at nuclear fuel fabrication plants especially dealing with low enriched uranium. For this purpose, a small size CZT (CdZnTe) detector was used, and the detector performance in low uranium gamma/X -rays energy range was investigated by use of various enriched uranium oxide samples. New enrichment measurement technique and analysis method for low enriched uranium oxide, so-called, 'semi-peak ratio technique' was developed. The newly developed method was considered as an alternative technique for the low enrichment and would be useful to account nuclear material in safeguarding activity at nuclear fuel fabrication facility.

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원자력 추진 잠수함의 특성과 농축우라늄 사용 (The characteristics of nuclear powered submarine and the use of enriched uranium)

  • 장준섭
    • Strategy21
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    • 통권41호
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    • pp.261-293
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    • 2017
  • Nuclear power is a way of attaining an enormous amount of energy with relatively small amount of resources and after it has been introduced to the submarine since 1954, there are approximately 150 of nuclear powered submarine currently on a mission around the world. This is due to the maneuverability, mountability and covertness of nuclear submarines. However, there are other tasks, not only the high level of nuclear technology that are needed to be dealt with in order to construct nuclear powered submarine. The biggest task of all is to secure the enriched uranium. Accordingly, this research is about the way of enriching and securing the nuclear fuel that are used in the nuclear submarine with the characteristics, merits and demerits of the nuclear submarine. Due to the fact that the pressurized water reactor in South Korea is the reactor that was originally built for the development of nuclear powered submarine, many parts is designed to be suitable for the submarine propulsion. However, in order to apply this to submarine it is needed to consider additional requests such as the position of reactor, accident-coping system, radioactive covering, reactor output adjustment and ship's pitch and roll in order to apply this to submarine. Nuclear submarines have much higher speed based on the powerful propulsion in comparison with diesel-electric submarine and also have bigger loading area. Besides, there is no need to snorkel and they also have advantages in covertness with the multi-noise proof system. The nuclear technology in South Korea has seen the dramatic development since 1962 and in 1998 reached to the level that we have succeeded in the localization of nuclear plant and exported the world-class one-piece small-sized reactor (SMART) to UAE. To operate these reactors, we import the whole quantity of low-enriched uranium and having our own uranium enrich facility is not probable because of the budget and international regulations. With the ROK/US nuclear agreement revised on 2015 November, the enrichment of uranium that are available without special permission has changed up to 20%. According to the assumption that we use the 20% enrichment of Uranium on U.S. virginia class submarine, it is necessary to change the fuel after 11 years and it will cause additional cost of 1 billion dollars. But the replace period by the uranium's enrichment rate is not fixed so that it is possible to change according to the design of reactor. Therefore, I would like to make a suggestion on two types of design concepts of nuclear submarine that can be operated for 30 years without nuclear fuel change by using the 20% enriched uranium from ONNp.First of all, it is possible by increasing the size of reactor by 3 times and it results in the 1,000t increase of the weight. And secondly, it is by designing the one piece reactor to insert devices such as steam turbine, condenser into the inside of nuclear core like the Rubis class submarines of France.

An investigative study of enrichment reduction impact on the neutron flux in the in-core flux-trap facility of MTR research reactors

  • Xoubi, Ned;Darda, Sharif Abu;Soliman, Abdelfattah Y.;Abulfaraj, Tareq
    • Nuclear Engineering and Technology
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    • 제52권3호
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    • pp.469-476
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    • 2020
  • Research reactors in-core experimental facilities are designed to provide the highest steady state flux for user's irradiation requirements. However, fuel conversion from highly enriched uranium (HEU) to low enriched uranium (LEU) driven by the ongoing effort to diminish proliferation risk, will impact reactor physics parameters. Preserving the reactor capability to produce the needed flux to perform its intended research functions, determines the conversion feasibility. This study investigates the neutron flux in the central experimental facility of two material test reactors (MTR), the IAEA generic10 MW benchmark reactor and the 22 MW s Egyptian Test and Research Reactor (ETRR-2). A 3D full core model with three uranium enrichment of 93%, 45%, and 20% was constructed utilizing the OpenMC particle transport Monte Carlo code. Neutronics calculations were performed for fresh fuel, the beginning of life cycle (BOL) and end of life cycle (EOL) for each of the three enrichments for both the IAEA 10 MW generic reactor and core 1/98 of the ETRR-2 reactor. Criticality calculations of the effective multiplication factor (Keff) were executed for each of the twelve cases; results show a reasonable agreement with published benchmark values for both reactors. The thermal, epithermal and fast neutron fluxes were tallied across the core, utilizing the mesh tally capability of the code and are presented here. The axial flux in the central experimental facility was tallied at 1 cm intervals, for each of the cases; results for IAEA 10 MW show a maximum reduction of 14.32% in the thermal flux of LEU to that of the HEU, at EOL. The reduction of the thermal flux for fresh fuel was between 5.81% and 9.62%, with an average drop of 8.1%. At the BOL the thermal flux showed a larger reduction range of 6.92%-13.58% with an average drop of 10.73%. Furthermore, the fission reaction rate was calculated, results showed an increase in the peak fission rate of the LEU case compared to the HEU case. Results for the ETRR-2 reactor show an average increase of 62.31% in the thermal flux of LEU to that of the HEU due to the effect of spectrum hardening. The fission rate density increased with enrichment, resulting in 34% maximum increase in the HEU case compared to the LEU case at the assemblies surrounding the flux trap.

콘크리트 폐기물의 자체처분을 위한 잔류방사능 조사 및 피폭선량평가 (Residual Radioactivity Investigation & Radiological Assessment for Self-disposal of Concrete Waste in Nuclear Fuel Processing Facility)

  • 설증군;류재봉;조석주;유성현;송정호;백훈;김성환;신진성;박현균
    • 방사성폐기물학회지
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    • 제5권2호
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    • pp.91-101
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    • 2007
  • 본 연구에서는 원전연료 가공시설에서 발생한 콘크리트 폐기물을 자체처분 하기 위란 국내 규제요건을 검토하였고, 매립 및 재활용에 따른 작업자 및 일반인의 방사선학적 위해도를 평가하기 위해 RESRAD Ver. 6.3, RESRAD BUILD Ver. 3.3 전산코드를 사용하여 피폭선량을 평가하였다. 피폭선량 평가 결과에 따라 유도된 처분제한치는 콘크리트 폐기물 매립의 경우 0.1071Bq/g (3.5% 농축우라늄), 재활용의 경우 $0.05515Bq/cm^2$(5% 농축우라늄)이었다. 또한, 자체처분대상 콘크리트 폐기물의 제염 후 잔류방사능을 조사한 결과, 표면오염도는 전체평균이 $0.01Bq/cm^2$(알파방출체), 콘크리트 폐기물 표면에서 채취한 시료의 방사성핵종 분석결과 $^{238}U$은 0.0297Bq/g, $^{235}U$의 농축도는 2w/o 이하였고, 인위적 오염으로 예상되는 $^{238}U$의 농도는 0.0089Bq/g 이었다. 따라서, 자체처분 대상 콘크리트 폐기물의 매립 및 재활용시 일반인 및 작업자에게 미치는 방사선학적 위해도는 원자력관계법령에서 정하는 처분제한치(개인선량 $10{\mu}Sv/yr$, 집단선량 $1man{\cdot}Sv/yr$) 이하임을 확인하였다.

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국내 원자력시설 및 핵연료 주기에 따른 핵감식 표지물질 활용에 대한 고찰 (A Literature Review on Application of Signature Materials in Nuclear Forensics according to Domestic Nuclear Facilities and Fuel Cycle)

  • 전여령;권다영;한지영;최우철;김용민
    • 한국방사선학회논문지
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    • 제15권1호
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    • pp.37-43
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    • 2021
  • 국내에는 다수의 원자력시설이 존재하며, 지리적으로 비핵화 대상국인 북한을 주변국으로 두고 있다. 변화하는 국제 정세에 따른 선제적 대응으로 대상시설에 대한 핵감식 데이터를 구축할 필요가 있다. 이를 위해 국내 원자력시설 및 핵연료 주기를 고려하여 핵물질 및 기타 방사성물질의 기원 또는 출처를 파악하는데 사용되는 표지물질을 제시하였다. 국내에서는 경수로 및 중수로를 운용하고 있으며 각각 핵연료로 농축 우라늄과 천연우라늄을 사용한다. 국내 선행핵연료주기에서 표지물질은 중수로형 원자력발전소의 연료인 천연우라늄과 우라늄 농축과정의 UF6으로 생각할 수 있다. 국내 후행핵연료주기는 재처리 과정을 제외된 비순환 주기를 채택하고 있어 주요 표지물질은 사용후핵연료가 된다. 해당 물질들에 대해 IAEA 문헌에서 권고하는 표지물질의 시그니처 중요도를 판단하고 조사 항목을 제시하였다. 향후 핵감식에서 핵물질 관리에 대한 무결성 입증과 국가 핵감식 역량을 높이기 위한 핵감식 라이브러리 구축을 위해 국내 원자력시설과 핵연료주기를 고려한 표지물질을 파악하고 해당물질 별 시그니처 데이터를 확보해야 할 것으로 생각된다.

Cyber attack taxonomy for digital environment in nuclear power plants

  • Kim, Seungmin;Heo, Gyunyoung;Zio, Enrico;Shin, Jinsoo;Song, Jae-gu
    • Nuclear Engineering and Technology
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    • 제52권5호
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    • pp.995-1001
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    • 2020
  • With the development of digital instrumentation and control (I&C) devices, cyber security at nuclear power plants (NPPs) has become a hot issue. The Stuxnet, which destroyed Iran's uranium enrichment facility in 2010, suggests that NPPs could even lead to an accident involving the release of radioactive materials cyber-attacks. However, cyber security research on industrial control systems (ICSs) and supervisory control and data acquisition (SCADA) systems is relatively inadequate compared to information technology (IT) and further it is difficult to study cyber-attack taxonomy for NPPs considering the characteristics of ICSs. The advanced research of cyber-attack taxonomy does not reflect the architectural and inherent characteristics of NPPs and lacks a systematic countermeasure strategy. Therefore, it is necessary to more systematically check the consistency of operators and regulators related to cyber security, as in regulatory guide 5.71 (RG.5.71) and regulatory standard 015 (RS.015). For this reason, this paper attempts to suggest a template for cyber-attack taxonomy based on the characteristics of NPPs and exemplifies a specific cyber-attack case in the template. In addition, this paper proposes a systematic countermeasure strategy by matching the countermeasure with critical digital assets (CDAs). The cyber-attack cases investigated using the proposed cyber-attack taxonomy can be used as data for evaluation and validation of cyber security conformance for digital devices to be applied, and as effective prevention and mitigation for cyber-attacks of NPPs.

APPLICATION OF FUZZY SET THEORY IN SAFEGUARDS

  • Fattah, A.;Nishiwaki, Y.
    • 한국지능시스템학회:학술대회논문집
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    • 한국퍼지및지능시스템학회 1993년도 Fifth International Fuzzy Systems Association World Congress 93
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    • pp.1051-1054
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    • 1993
  • The International Atomic Energy Agency's Statute in Article III.A.5 allows it“to establish and administer safeguards designed to ensure that special fissionable and other materials, services, equipment, facilities and information made available by the Agency or at its request or under its supervision or control are not used in such a way as to further any military purpose; and to apply safeguards, at the request of the parties, to any bilateral or multilateral arrangement, or at the request of a State, to any of that State's activities in the field of atomic energy”. Safeguards are essentially a technical means of verifying the fulfilment of political obligations undertaken by States and given a legal force in international agreements relating to the peaceful uses of nuclear energy. The main political objectives are: to assure the international community that States are complying with their non-proliferation and other peaceful undertakings; and to deter (a) the diversion of afeguarded nuclear materials to the production of nuclear explosives or for military purposes and (b) the misuse of safeguarded facilities with the aim of producing unsafeguarded nuclear material. It is clear that no international safeguards system can physically prevent diversion. The IAEA safeguards system is basically a verification measure designed to provide assurance in those cases in which diversion has not occurred. Verification is accomplished by two basic means: material accountancy and containment and surveillance measures. Nuclear material accountancy is the fundamental IAEA safeguards mechanism, while containment and surveillance serve as important complementary measures. Material accountancy refers to a collection of measurements and other determinations which enable the State and the Agency to maintain a current picture of the location and movement of nuclear material into and out of material balance areas, i. e. areas where all material entering or leaving is measurab e. A containment measure is one that is designed by taking advantage of structural characteristics, such as containers, tanks or pipes, etc. To establish the physical integrity of an area or item by preventing the undetected movement of nuclear material or equipment. Such measures involve the application of tamper-indicating or surveillance devices. Surveillance refers to both human and instrumental observation aimed at indicating the movement of nuclear material. The verification process consists of three over-lapping elements: (a) Provision by the State of information such as - design information describing nuclear installations; - accounting reports listing nuclear material inventories, receipts and shipments; - documents amplifying and clarifying reports, as applicable; - notification of international transfers of nuclear material. (b) Collection by the IAEA of information through inspection activities such as - verification of design information - examination of records and repo ts - measurement of nuclear material - examination of containment and surveillance measures - follow-up activities in case of unusual findings. (c) Evaluation of the information provided by the State and of that collected by inspectors to determine the completeness, accuracy and validity of the information provided by the State and to resolve any anomalies and discrepancies. To design an effective verification system, one must identify possible ways and means by which nuclear material could be diverted from peaceful uses, including means to conceal such diversions. These theoretical ways and means, which have become known as diversion strategies, are used as one of the basic inputs for the development of safeguards procedures, equipment and instrumentation. For analysis of implementation strategy purposes, it is assumed that non-compliance cannot be excluded a priori and that consequently there is a low but non-zero probability that a diversion could be attempted in all safeguards ituations. An important element of diversion strategies is the identification of various possible diversion paths; the amount, type and location of nuclear material involved, the physical route and conversion of the material that may take place, rate of removal and concealment methods, as appropriate. With regard to the physical route and conversion of nuclear material the following main categories may be considered: - unreported removal of nuclear material from an installation or during transit - unreported introduction of nuclear material into an installation - unreported transfer of nuclear material from one material balance area to another - unreported production of nuclear material, e. g. enrichment of uranium or production of plutonium - undeclared uses of the material within the installation. With respect to the amount of nuclear material that might be diverted in a given time (the diversion rate), the continuum between the following two limiting cases is cons dered: - one significant quantity or more in a short time, often known as abrupt diversion; and - one significant quantity or more per year, for example, by accumulation of smaller amounts each time to add up to a significant quantity over a period of one year, often called protracted diversion. Concealment methods may include: - restriction of access of inspectors - falsification of records, reports and other material balance areas - replacement of nuclear material, e. g. use of dummy objects - falsification of measurements or of their evaluation - interference with IAEA installed equipment.As a result of diversion and its concealment or other actions, anomalies will occur. All reasonable diversion routes, scenarios/strategies and concealment methods have to be taken into account in designing safeguards implementation strategies so as to provide sufficient opportunities for the IAEA to observe such anomalies. The safeguards approach for each facility will make a different use of these procedures, equipment and instrumentation according to the various diversion strategies which could be applicable to that facility and according to the detection and inspection goals which are applied. Postulated pathways sets of scenarios comprise those elements of diversion strategies which might be carried out at a facility or across a State's fuel cycle with declared or undeclared activities. All such factors, however, contain a degree of fuzziness that need a human judgment to make the ultimate conclusion that all material is being used for peaceful purposes. Safeguards has been traditionally based on verification of declared material and facilities using material accountancy as a fundamental measure. The strength of material accountancy is based on the fact that it allows to detect any diversion independent of the diversion route taken. Material accountancy detects a diversion after it actually happened and thus is powerless to physically prevent it and can only deter by the risk of early detection any contemplation by State authorities to carry out a diversion. Recently the IAEA has been faced with new challenges. To deal with these, various measures are being reconsidered to strengthen the safeguards system such as enhanced assessment of the completeness of the State's initial declaration of nuclear material and installations under its jurisdiction enhanced monitoring and analysis of open information and analysis of open information that may indicate inconsistencies with the State's safeguards obligations. Precise information vital for such enhanced assessments and analyses is normally not available or, if available, difficult and expensive collection of information would be necessary. Above all, realistic appraisal of truth needs sound human judgment.

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