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Ämnesområden: Klyvbara material
Kommittébeteckning: SIS/TK 405 (Kärnenergi)
Källa: ISO
Svarsdatum: den 23 feb 2018
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This method applies to the measurement of the isotopic composition and the concentration of uranium and plutonium in input solutions of irradiated Magnox and light water reactor fuels (boiling water reactor or pressurized water reactor), in final products at spent-fuel reprocessing plants, and in feed and products of MOX and uranium fuel fabrication. The method is applicable to other fuels, but the chemical separation and spike solution are, if necessary, adapted to suit each type of fuel.

Ämnesområden: Klyvbara material
Kommittébeteckning: SIS/TK 405 (Kärnenergi)
Källa: ISO
Svarsdatum: den 28 feb 2018
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This International Standard provides the chemical analyzers with a method for evaluation of the measurement uncertainty arising when an impurity content of uranium solution is determined by a regression line that has been fitted by the "method of least squares".

Simple linear regression, hereinafter called "basic regression", is defined as a model with a single independent variable that is applied to fit a regression line through n different data points (xi, yi) (i = 1,…, n) in such a way that makes the sum of squared errors, i.e. the squared vertical distances between the data points and the fitted line, as small as possible. For the linear calibration, "classical regression" or "inverse regression" is usually used; however, they are inconvenient to use. Instead, "reversed inverse regression" is used in this International Standard[1].

Reversed inverse regression treats y (the reference solutions) as the response and x (the observed measurements) as the inputs; these values are used to fit a regression line of y on x by the method of least squares. This regression is distinguished from basic regression in that the xi’s (i = 1,…, n) vary according to normal distributions but the yi’s (i = 1,…, n) are fixed; in basic regression, the yi’s vary but the xi’s are fixed.

The regression line fitting, calculation of combined uncertainty, calculation of effective degrees of freedom, calculation of expanded uncertainty, reflection of reference solutions’ uncertainties in the evaluation result, and bias correction are explained in order of mention. Annex A presents a practical example of uncertainty evaluation. Annex B provides a flowchart showing the steps for uncertainty evaluation. In addition, Annex C explains the use of weighting factors for handling non-uniform variances in reversed inverse regression.

NOTE 1 In the case of classical regression, the fitted regression line must be inverted prior to actual sample measurement[2]. In the case of inverse regression, the roles of x and y are not consistent with the convention that the variable x represents the inputs, whereas the variable y represents the response. For these reasons, the two regressions are excluded from this International Standard.

NOTE 2 The term "reversed inverse regression" was suggested taking into account the history of regression analysis theory. Instead, it may be desirable to use some other term, e.g. "pseudo-basic regression".

Kommittébeteckning: SIS/TK 405 (Kärnenergi)
Källa: ISO
Svarsdatum: den 19 mar 2018
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This international standard describes methods to determine the activity in becquerel (Bq) of gamma-emitting radionuclides by gamma spectrometry in solid, liquid or gaseous test samples after proper preparation in a testing laboratory. Applications include:

— routine surveillance of radioactivity released from nuclear installations or from sites discharging enhanced levels of naturally occurring radioactive materials;

— contributing to determining the evolution of radioactivity in the environment;

— investigating accident and incident situations, in order to plan remedial actions and monitor their effectiveness;

— assessing potentially contaminated waste materials from decommissioning legacy nuclear sites;

— surveillance of radioactive contamination in media such as soils, foodstuffs, potable water, groundwaters, seawater or sewage sludge;

— measurements for estimating the intake (inhalation, ingestion or injection) of activity of gamma-emitting radionuclides in the body.

It is assumed that the user of this standard has been given information on the composition of the test sample (or the site). In some cases, the radionuclides for analysis may also have been specified if characteristic limits are required. It is also assumed that the test sample has been homogenised and is representative of the material under test.

General guidance is included for preparing the samples for measurement. However, some types of sample are to be prepared following the requirements of specific standards referred to in this document. The generic recommendations can also be useful for the measurement of gamma emitters in situ.

This standard includes generic advice on equipment selection (a list of factors to be considered) (more detailed information is included in Annex A), detectors (more detailed information is included in Annex D), and commissioning of instrumentation and method validation. The informative Annex F summarises the influence of different measurement parameters on results for a typical gamma spectrometry system. Quality control and routine maintenance are also covered, but electrical testing of the detector and pulse processing electronics is excluded. It is assumed that any data collection and analysis software used has been written and tested in accordance with relevant software standards such as ISO/IEC 12207.

Calibration using reference materials and/or numerical methods is covered, including verification of the results. It also covers the procedure to estimate the activity content of the sample (Bq) from the spectrum. The procedure for the measurement of gamma emitting radionuclides in situ is covered in ISO 18589-7 and is outside the scope of this document.

The standard covers, but is not restricted to, gamma emitters which emit photons in the energy range of 5 keV to 3000 keV. However, the most measurements fall into the range 40 keV to 2 000 keV. The activity (Bq) ranges from the low levels (sub-Bq) found in environmental samples to activities found in accident conditions and high level radioactive wastes.

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This document specifies requirements and test methods for factory made thermally insulated bonded fitting assemblies for hot water networks in accordance with prEN 13941-1, comprising a steel service fitting, rigid polyurethane foam insulation and a casing of polyethylene.

The fitting assembly may also include the following additional elements: measuring wires, spacers and diffusion barriers.

This document covers the following fitting assemblies: bend, tee, reducer, single use compensator and anchor.

This document applies to fitting assemblies with a minimum design pressure of 16 bar (overpressure).

Kommittébeteckning: SIS/TK 300 (Förtillverkade fjärrvärmerör)
Källa: CEN
Svarsdatum: den 29 mar 2018
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This document specifies requirements and test methods for factory made thermally insulated bonded valve assemblies for hot water networks in accordance with prEN 13941-1, comprising a steel valve, rigid polyurethane foam insulation and a casing of polyethylene.

The valve assembly may also include the following additional elements: measuring wires, spacers and diffusion barriers.

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This document specifies requirements and test methods for surveillance systems for directly buried hot water networks in accordance with prEN 13941-1.

This document specifies requirements for the manufacture of measuring elements, for the manufacture of factory made bonded pipe, fitting and valve assemblies with measuring elements as well as for the assembly of the measuring elements in the field.

All requirements and recommendations described in this document are based on the experience gained with existing surveillance systems and their principle function.

The specific requirements given are only valid for electrical wire based surveillance systems forming an integral part of the pipes, valves, fittings and joints.

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This document specifies requirements and test methods for straight lengths of factory made thermally insulated bonded twin pipe assemblies for directly buried hot water networks in accordance with prEN 13941-1, comprising two steel service pipes, rigid polyurethane foam insulation and one casing of polyethylene.

The pipe assembly can also include the following additional elements: Measuring wires, spacers and diffusion barriers.

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This document specifies requirements and test methods for fittings of factory made thermally insulated bonded twin pipe assemblies for hot water networks in accordance with prEN 13941-1, comprising two steel service fittings and/or valves, rigid polyurethane foam insulation and one casing of polyethylene.

The pipe assembly can also include the following additional elements: Measuring wires, spacers and diffusion barriers.

This document covers the following assemblies:

— fittings: bends, T-pieces, reducers and anchors;

— valves constructions.

This document applies to fitting and valve assemblies with a minimum design pressure of 16 bar (overpressure).