Calculation of isotope-specific exemption levels for surface contamination

Ogino, Haruyuki; Hattori, Takatoshi

doi:10.1016/j.apradiso.2009.02.007

Cited by 9 publications

(17 citation statements)

References 5 publications

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“…In the previous studies, 7,8) the dose assessment model was based on a deterministic method and the exemption dose criteria were chosen to be 0.01 mSv/y in the case of using realistic parameters and 1 mSv/y in the case of using low-probability parameters, in accordance with the IAEA Basic Safety Standards (BSS) 10) and the safety guide RS-G-1. 7.…”

Section: Criteria Of Judging Validitymentioning

confidence: 99%

“…In the deterministic dose assessment model in the previous studies, 7,8) external irradiation, ingestion, inhalation and skin contamination were considered as exposure pathways, where the skin contamination was examined only to verify that the equivalent doses to the skin were below 50 mSv/y, that is, one-tenth of 500 mSv/y as dose equivalent limit, and isotopespecific exemption levels for surface contamination were derived for 20 representative nuclides:…”

Section: Choice Of Nuclidesmentioning

confidence: 99%

“…In the developed deterministic dose assessment model used in the previous studies, 7,8) however, the exposure scenarios were classified into three types, and each scenario was evaluated with manually handled objects, closely handled objects and remotely handled objects. The three objects were modeled as having a at square surface and assumed to have areas of 0.1, 1 and 10 m 2 , respectively.…”

Section: Probabilistic Dose Assessment Model 241 E Posure Scenariomentioning

confidence: 99%

“…To solve the problems, we have originally developed 7,8) a deterministic radiological dose assessment model for surface contamination that can be applied throughout radiation, transport and waste safety elds, applying consistent radiation protection systems against low-level ionizing radiation. In the result, consistent isotope-specific exemption levels for surface contamination were derived for 20 nuclides, chosen as representative nuclides in the major nuclear facilities by the Nuclear Safety Commission (NSC) of Japan Am.…”

Section: Introductionmentioning

confidence: 99%

“…In the result, consistent isotope-specific exemption levels for surface contamination were derived for 20 nuclides, chosen as representative nuclides in the major nuclear facilities by the Nuclear Safety Commission (NSC) of Japan Am. In the deterministic radiological dose assessment model developed in the previous studies, 7,8) the parameters were conservatively assumed to be single values and exemption levels for surface contamination were consequently calculated as single values. However, the parameters are no longer single values but have certain distributions in consideration of realistic exposure situations.…”

Section: Introductionmentioning

confidence: 99%

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Verification of Validity of Isotope-Specific Exemption Levels for Surface Contamination Using Monte Carlo Calculation

Ogino

Hattori

2009

Jpn. J. Health Phys.

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Current surface contamination density standards are conservatively determined not for each nuclide but by the type of emitter. In the previous studies, isotope-speci c exemption levels for surface contamination for representative nuclides were originally derived by developing a deterministic dose assessment model that can be applied throughout radiation, transport and waste safety elds. In this study, the effects of uncertainty in assumed parameters on the derived exemption levels were examined by developing a probabilistic dose assessment model using the Monte Carlo calculation. The criteria for the judgment of validities of the derived exemption levels were decided applying the concept of the representative person given by the International Commission on Radiological Protection (ICRP), the set of minimum dose constraint for the optimization of the radiological protection of the public revealed in a recent study and the probabilistic dose assessment model developed by the Nuclear Safety Commission (NSC) of Japan. Moreover, the effects of correlation in parameters on the results of probabilistic dose assessment are probabilistically examined by developing the function of specifying the random seeds independently for each parameter in the Monte Carlo calculation. These results verify the validity of the deterministically derived isotopespeci c exemption levels for surface contamination.

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Section: Criteria Of Judging Validitymentioning

confidence: 99%

Section: Choice Of Nuclidesmentioning

confidence: 99%

Section: Probabilistic Dose Assessment Model 241 E Posure Scenariomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Verification of Validity of Isotope-Specific Exemption Levels for Surface Contamination Using Monte Carlo Calculation

Ogino

Hattori

2009

Jpn. J. Health Phys.

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SUDOQU, a new dose-assessment methodology for radiological surface contamination

Dillen

Dijk²

2018

J. Radiol. Prot.

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A new methodology has been developed for the assessment of the annual effective dose resulting from removable and fixed radiological surface contamination. It is entitled SUDOQU (SUrface DOse QUantification) and it can for instance be used to derive criteria for surface contamination related to the import of non-food consumer goods, containers and conveyances, e.g., limiting values and operational screening levels. SUDOQU imposes mass (activity)-balance equations based on radioactive decay, removal and deposition processes in indoor and outdoor environments. This leads to time-dependent contamination levels that may be of particular importance in exposure scenarios dealing with one or a few contaminated items only (usually public exposure scenarios, therefore referred to as the 'consumer' model). Exposure scenarios with a continuous flow of freshly contaminated goods also fall within the scope of the methodology (typically occupational exposure scenarios, thus referred to as the 'worker model'). In this paper we describe SUDOQU, its applications, and its current limitations. First, we delineate the contamination issue, present the assumptions and explain the concepts. We describe the relevant removal, transfer, and deposition processes, and derive equations for the time evolution of the radiological surface-, air- and skin-contamination levels. These are then input for the subsequent evaluation of the annual effective dose with possible contributions from external gamma radiation, inhalation, secondary ingestion (indirect, from hand to mouth), skin contamination, direct ingestion and skin-contact exposure. The limiting effective surface dose is introduced for issues involving the conservatism of dose calculations. SUDOQU can be used by radiation-protection scientists/experts and policy makers in the field of e.g. emergency preparedness, trade and transport, exemption and clearance, waste management, and nuclear facilities. Several practical examples are worked out demonstrating the potential applications of the methodology.

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Verification of screening level for decontamination implemented after Fukushima nuclear accident

Ogino

Ichiji

Hattori

2012

Radiation Protection Dosimetry

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The screening level for decontamination that has been applied for the surface of the human body and contaminated handled objects after the Fukushima nuclear accident was verified by assessing the doses that arise from external irradiation, ingestion, inhalation and skin contamination. The result shows that the annual effective dose that arises from handled objects contaminated with the screening level for decontamination (i.e. 100 000 counts per minute) is <1 mSv y−1, which can be considered as the intervention exemption level in accordance with the International Commission on Radiological Protection recommendations. Furthermore, the screening level is also found to protect the skin from the incidence of a deterministic effect because the absorbed dose of the skin that arises from direct deposition on the surface of the human body is calculated to be lower than the threshold of the deterministic effect assuming a practical exposure duration.

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Calculation of isotope-specific exemption levels for surface contamination

Cited by 9 publications

References 5 publications

Verification of Validity of Isotope-Specific Exemption Levels for Surface Contamination Using Monte Carlo Calculation

Verification of Validity of Isotope-Specific Exemption Levels for Surface Contamination Using Monte Carlo Calculation

SUDOQU, a new dose-assessment methodology for radiological surface contamination

Verification of screening level for decontamination implemented after Fukushima nuclear accident

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